JP2009167039A - Method for storing glass article and method for manufacturing lens glass material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for storing a glass article, by which the appearance of a latent flaw can be suppressed; and to provide a method for manufacturing a lens glass material using the same. <P>SOLUTION: In the method for storing a glass article in water, water containing one or more kinds of the same components as the glass components constituting the glass article is used as a storing solution. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an underwater storage method for glass articles, particularly lens glass materials.

For applications such as optical pickup lenses for CD, MD, DVD and other optical disk systems, imaging lenses for digital cameras, video cameras, camera-equipped mobile phones, and transmission / reception lenses used for optical communications, aspherical lenses are used. Widely used. As glass used for this kind of application, for example, B ₂ O ₃ —La ₂ O ₃ —ZnO—Gd ₂ O ₅ glass is disclosed in Patent Document 1, and SiO ₂ —B ₂ O ₃ —R′O—R _2. O-type glass is described in Patent Document 2, respectively.

  As a method for manufacturing the aspherical lens, for example, the following method is known. First, molten glass is dropped from the tip of a nozzle to produce droplet glass (droplet molding), and grinding, polishing, and washing are performed to produce a lens glass material. Alternatively, a molten glass is rapidly cast to produce a glass ingot, which is then ground, polished and washed to produce a lens glass material. Subsequently, the lens glass material is heated and softened, pressure-molded by a mold having a highly accurate molding surface, and the surface shape of the mold is transferred to glass to produce a lens.

Such a manufacturing method is generally called a mold press molding method, and has been widely adopted in recent years as a method suitable for mass production.
JP 2007-137701 A JP 2005-350279 A

  The lens glass material produced by the above method usually undergoes one or more polishing steps. In general, the lens glass material is stored after the polishing step or between each polishing step in order to prevent the polishing material and the like from adhering to the surface.

  However, when the lens glass material is stored underwater, scratches called latent scratches may appear on the surface. This is thought to be due to the fact that minute invisible scratches formed by polishing are attacked by water and grow large. Therefore, conventionally, measures have been taken to improve the process so that the storage time in water after polishing is as short as possible, and production plans have been adjusted.

  An object of the present invention is to provide a storage method in which latent scratches do not appear even when stored in water for a long time, and a glass glass material manufacturing method using the same.

  The glass article storage method of the present invention is characterized in that, in the method of storing a glass article in water, water containing at least one component identical to the glass component constituting the glass article is used as a storage liquid. In the present invention, the “glass article” means a glass article made of multicomponent glass.

In the storage method of the present invention, the glass article is preferably made of B ₂ O ₃ -containing glass, and the storage liquid is preferably water containing a B component. In the present invention, “B ₂ O ₃ -containing glass” means glass containing B ₂ O ₃ in the glass composition. “Water containing B component” means water containing B element in an ionic state.

In the storage method of the present invention, the glass article is preferably made of glass containing R ₂ O (R is an alkali metal), and the storage liquid is water containing an R component. In the present invention, “R ₂ O-containing glass” means a glass containing at least one of Li ₂ O, Na ₂ O, and K ₂ O in the glass composition. “Water containing R component” means water containing the same element as the alkali metal contained in the glass in an ionic state.

  In the storage method of the present invention, the glass article is preferably made of glass containing R′O (R ′ is an alkaline earth metal), and the storage solution is water containing an R ′ component. In the present invention, “R′O-containing glass” means a glass containing at least one of MgO, CaO, SrO and BaO in the glass composition. “Water containing R ′ component” means water containing the same element as the alkaline earth metal contained in the glass in an ionic state.

According to these configurations, the effects of the method of the present invention can be further enjoyed. That is, B ₂ O ₃ , R ₂ O or R′O is a component that is easily eluted from the glass, and glass containing these components often has low water resistance. Therefore, if it is a normal storage method, this kind of glass is likely to grow fine scratches on the glass surface because B ₂ O ₃ , R ₂ O or R′O components are eluted from the glass by contact with water. Inconvenience occurs. Then, if the method of this invention is applied with respect to such glass, the growth of the fine crack of glass can be prevented effectively.

  In the storage method of the present invention, the storage liquid is preferably prepared by adding, in water, a glass material containing at least one component that is the same as the glass component constituting the glass article.

  According to this structure, the water (storage liquid) containing at least 1 sort (s) of the glass component which comprises a glass article can be produced easily.

  In the storage method of the present invention, the glass material is preferably made of glass having the same composition as the glass article.

  According to this configuration, even if it is not confirmed in advance which elution of the components of the glass constituting the glass article is deeply related to the growth of the scratch on the glass article, it is possible to effectively grow the fine scratch on the glass. Can be prevented.

  In the storage method of the present invention, the glass material is preferably in a powder form.

  According to this structure, it becomes easy to elute a glass component from a glass material, and the elution of the glass component from a glass article can be suppressed further. Therefore, it is possible to effectively prevent the growth of fine scratches on the glass.

  In the storage method of the present invention, the glass article is preferably a lens glass material. “Lens glass material” means a preform for lens production.

  According to this configuration, it is possible to further enjoy the effects of the method of the present invention. That is, if there is a latent flaw in the lens glass material, inconveniences such as a decrease in transmittance and a deterioration in image quality occur. However, if the method of the present invention is applied, the growth of fine scratches on the glass can be prevented. Therefore, the above inconvenience can be effectively avoided.

  In the storage method of the present invention, the lens glass material is preferably a lens glass material for mold press molding.

  According to this configuration, it is possible to further enjoy the effects of the method of the present invention. That is, as the lens glass material for mold press molding, glass having a low softening point is used in order to enable press molding at a low temperature. Such a low softening point glass is generally characterized by low chemical durability, and there is a high possibility that latent scratches will occur due to storage in water. If the method of the present invention is applied to such a glass, the growth of fine scratches on the glass can be prevented, so that the above disadvantages can be effectively avoided.

  The lens glass material manufacturing method of the present invention is characterized in that in the lens glass material manufacturing method including a polishing step, the lens glass material is stored after the polishing step by the above method.

  According to this configuration, it is possible to further enjoy the effects of the method of the present invention. That is, the lens glass material manufacturing method generally includes a polishing step. After the polishing process, the lens glass material is dried and packed through a cleaning process. Storage of the lens glass material until the drying process is stored in water to prevent the abrasive and the like from adhering to the surface. Therefore, it is important to prevent the occurrence of latent scratches due to storage in water as much as possible. Therefore, this requirement can be sufficiently satisfied by applying the manufacturing method of the present invention.

  In the production method of the present invention, the glass powder generated in the polishing step is preferably used as the glass material.

  This configuration is economical because it is not necessary to prepare a glass material separately. Moreover, since it is powdery, it becomes easy to elute a glass component from a glass material, the elution of the glass component from a glass article can be suppressed further, and the growth of the fine crack of glass is prevented effectively. Can do.

  In the storage method of the present invention, the storage liquid contains one or more components that are the same as the components of the glass constituting the glass article. The presence of this component in the liquid can suppress the situation where the same component is eluted from the glass article. Therefore, the method of the present invention is a storage method capable of suppressing the latent damage of the glass article.

  In the glass article storage method of the present invention, the glass article to be stored is not limited, but is preferably an article that is not to be dried during storage, such as a lens glass material after polishing. In the case of a lens glass material after polishing, when the lens glass material is dried, the polishing material or the like adheres to the surface, making it difficult to remove in a later step.

When the glass article is a lens glass material, for example, B ₂ O ₃ , alkali metal component R ₂ O (Na ₂ O, K ₂ O, Li ₂ O), alkaline earth metal component R′O (MgO, CaO, SrO, BaO) ) And the like made of glass with low chemical durability is preferable because the effects of the method of the present invention can be further enjoyed. More specifically, it is preferable to use a glass containing these components in a total amount of 20% by mass or more, particularly 25% by mass or more. The upper limit of the total amount of these components is preferably 60% by mass or less, and particularly preferably 55% by mass or less.

  When the lens glass material is molded by press molding, it is desirable to use a glass having a softening point of 650 ° C. or lower, particularly 630 ° C. or lower.

Examples of the glass that is suitable for a lens glass material for mold press molding and that easily causes latent scratches when stored in water include B ₂ O ₃ —La ₂ O ₃ —ZnO—Gd ₂ O ₅ glass, SiO ₂ —B ₂ O _3. -R'O-R ₂ O-based glass, and the like.

B ₂ O ₃ —La ₂ O ₃ —ZnO—Gd ₂ O ₅ glass is, by mass, B ₂ O ₃ 24-45%, La ₂ O ₃ 5-35%, ZnO 10-30%, Ta ₂ O ₅ 0-10%, Li ₂ O 2-10%, Na ₂ O 0-5%, K ₂ O 0-5%, R ₂ O (R is one or more of Li, Na, K) 0-15 %, SiO ₂ 6-20%, Al ₂ O ₃ 0-10%, MgO 0-10%, BaO 0-10%, SrO 0-15%, R′O (R ′ is a kind of Mg, Ba, Sr) Above) Glass containing 0 to 25%, ZrO ₂ 0 to 5%, Y ₂ O ₃ 0 to 15%, Gd ₂ O ₃ 0.5 to 20%, Sb ₂ O ₃ 0 to 1% is exemplified.

The SiO ₂ —B ₂ O ₃ —R′O—R ₂ O-based glass is, by mass, SiO ₂ 42-60%, B ₂ O ₃ 2-10%, CaO 0.5-11%, BaO 3. ˜17%, SrO 0-10%, Li ₂ O 2-10%, ZrO ₂ 0-3%, La ₂ O ₃ 0-2.5%, Li ₂ O, Na ₂ O and K ₂ O The glass whose total amount is 3 to 12% is exemplified.

In the glass article storage method of the present invention, water containing at least one component identical to the glass component constituting the glass article is used as the storage liquid used for storage. As components contained in water, components that are easily eluted into water from glass articles, such as B ₂ O ₃ , alkali metal components R ₂ O (Na ₂ O, K ₂ O, Li ₂ O), alkaline earth metal components R ′ O (MgO, CaO, SrO, BaO) etc. are mentioned. However, since easiness of elution of glass constituent components into water varies depending on the glass composition system, it is important to investigate in advance the glass articles to be stored and select appropriate components.

The stock solution can be prepared in various ways. As a simple method, there is a method in which a glass material containing at least one of the same components as the glass components constituting the glass article is added to water. If a glass material as described above is added to water, each component in the glass material is eluted in water, so that a predetermined storage solution can be obtained. For example, B ₂ O ₃ , alkali metal component R ₂ O (Na ₂ O, K ₂ O, Li ₂ O), alkaline earth metal component R′O (MgO, CaO, SrO, BaO) and the like are desired to be contained in water. In such a case, a glass material containing these components may be employed. The most preferable material for the glass material has the same composition as the glass constituting the glass article.

  There are no particular restrictions on the shape, size, etc. of the glass material. For example, glass materials having various shapes such as a lump shape, a rod shape, a granular shape, a powder shape, or the same shape as a glass article (a glass article that has become difficult to be used as a product for some reason) can be used. In selecting the shape of the glass material, etc., it may be determined in consideration of the elution rate and elution amount of the glass component. In this respect, it is desirable that the shape has a large specific surface area, particularly a powder. In addition, when used in actual production, it is necessary to consider the ease of management so that a homogeneous storage solution can always be obtained. From this point of view, it is important to always manage the particle size (specific surface area) to be constant. From the above, it is preferable to adopt a powdery product controlled to a constant particle size, for example, a 250 mesh pass product.

  In addition, when using the storage liquid, it is OK to use one that contains glass material, but if you want to prevent unforeseen circumstances, such as damage to glass articles due to glass material, It is desirable to use a liquid from which the glass material has been removed or a supernatant.

  The method for manufacturing a lens glass material of the present invention includes a polishing process and a storage process of the lens glass material.

  For example, in the case of a lens glass material for mold press molding, high sphericity is required in order to perform mold press molding with high accuracy. In order to meet this requirement, the lens glass material is polished. The degree and number of polishing are determined according to the degree of sphericity of the glass material at the time of molding.

  The lens lens material after polishing is stored in water. The underwater storage method is as described above. The reason for storage in water will be described below. That is, the polished lens glass material is finally cleaned and dried, and then packed. By the time this cleaning process is reached, it is necessary to prevent the surface of the lens glass material from having unremovable dirt. Therefore, the purpose of storage in water is to prevent such contamination, specifically, sticking of the abrasive.

  Although the storage liquid to be used is as described above, in the present manufacturing method, it is most preferable to prepare the storage liquid using glass powder generated by polishing the lens glass material as the glass material. When using the glass powder generated by polishing, it is preferable to classify and use after making the particle size constant. For example, glass powder that has passed a 250-mesh sieve can be used.

  In addition, regarding the molding of the lens glass material, any method such as a method in which molten glass is dropped from the tip of the nozzle and molded, a method in which the molten glass is rapidly cast and a glass ingot is once cut out is adopted. Good.

  In addition, after storage in water, the lens glass material may be quickly washed with an acidic solution or an alkaline solution, dried, and then packed.

  The lens glass material thus produced can be formed into a lens by, for example, the following method (mold press molding method).

  First, the lens glass material is placed in a precision molded mold. Next, pressure is applied while heating until the lens glass material is in a softened state, and the surface state of the mold is transferred to the glass. In this way, a lens having a desired shape is formed.

  Hereinafter, the method of the present invention will be described in detail based on examples. Table 1 shows Examples (Sample Nos. 2 and 3) and Comparative Example (No. 1) of the method of the present invention.

First, B ₂ O ₃ 25.0%, La ₂ O ₃ 7.1%, ZnO 28.5%, Gd ₂ O ₅ 2.9%, Li ₂ O 5.0%, SiO ₂ 9.9 by mass%. %, BaO 3.1%, SrO 14.5%, Ta ₂ O ₅ 2.1%, Y ₂ O ₃ 1.9% B ₂ O ₃ —La ₂ O ₃ —ZnO—Gd ₂ O A substantially spherical shaped body of ₅ series glass (softening point 564 ° C.) was prepared. Next, this glass molded body was polished to produce a lens glass material (mass of 233 mg / piece) having a sphericity of 1 μm.

  Next, five lens glass materials (1165 mg) were stored in the storage solution (10 ° C., 0.03 L) shown in Table 1 for 1 to 72 hours.

  The storage liquid 1 in Table 1 is a supernatant after adding 3 g of a pulverized lens glass material (250 mesh pass) to pure water at 30 ° C. and holding for 140 hours. The storage liquid 2 is a supernatant liquid after adding 3 g of a pulverized lens glass material (250 mesh pass) to pure water at 10 ° C. and holding for 1 minute. Table 2 shows glass components contained in the storage liquids 1 and 2.

  In this embodiment, a pulverized lens glass material is used as a glass material for preparing the storage liquid, but glass powder generated by polishing may be used. In addition, a glass beaker was used for the preparation of the storage liquid and the storage of the lens glass material in the liquid, but a container without deterioration such as a stainless steel container may be used for mass production.

  The surface state of the lens glass material after storage was observed visually and with a microscope (15 times). The results are shown in Table 1.

  As apparent from Table 1, Samples 2 and 3 using the method of the present invention showed no latent scratch on the glass surface over a long period of time.

  In addition, the surface condition of the lens glass material was “◯” when the latent image could not be confirmed by microscopic observation, and could not be confirmed with the naked eye, but “△” when the microscope could confirm the latent image could be confirmed with the naked eye. (Appeared as white powder squirted on the glass surface) was represented as “x”.

  The glass article storage method of the present invention can be applied to various glass article storage methods, such as optical pickup lenses, digital cameras, video cameras, camera-equipped mobile phones for various optical disk systems such as CD, MD, DVD, etc. It can be used as a storage method in the manufacturing process of glass materials for optical lenses such as imaging lenses and transmission / reception lenses used for optical communication. In particular, it is suitable as a storage method in the manufacturing process of the lens glass material to be mold press molded.

  The lens glass material manufacturing method of the present invention includes, for example, optical pickup lenses for various optical disk systems such as CD, MD, DVD, imaging lenses for digital cameras, video cameras, camera-equipped mobile phones, and transmission / reception used for optical communication. It can be used as a method for producing a glass material for an optical lens such as a lens. In particular, it is suitable as a method for producing a lens glass material to be molded press-molded.

Claims (11)

  In the method for storing glass articles in water, the glass article storage method is characterized in that water containing one or more components identical to the glass components constituting the glass articles is used as a storage liquid. The glass article storage method according to claim 1, wherein the glass article is made of B ₂ O ₃ -containing glass, and the storage liquid is water containing a B component. The glass article storage method according to claim 1 or 2, wherein the glass article is made of glass containing R ₂ O (R is an alkali metal), and the storage liquid is water containing an R component.   The glass article storage method according to any one of claims 1 to 3, wherein the glass article is made of glass containing R'O (R 'is an alkaline earth metal), and the storage liquid is water containing an R' component. .   5. The method for storing glass articles according to claim 1, wherein the storage liquid is prepared by adding, in water, a glass material containing at least one of the same components as the glass components constituting the glass article.   6. The glass article storage method according to claim 5, wherein the glass material is made of glass having the same composition as that of the glass article.   7. The glass article storage method according to claim 5, wherein the glass material is in a powder form.   The glass article according to claim 1, wherein the glass article is a lens glass material.   9. The glass article storage method according to claim 8, wherein the lens glass material is a lens glass material for mold press molding.   A lens glass material manufacturing method including a polishing step, wherein the lens glass material is stored after the polishing step by the method according to any one of claims 1 to 9.   11. The method for producing a lens glass material according to claim 10, wherein glass powder generated in the polishing step is used as the glass material.