JP2005145814A - Glass composition and method of producing glass article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass composition by which glass is made homogeneous and a method of producing a glass article by which the production condition is established, the compositional homogeneity of produced glass is accurately evaluated and the occurrence of needless coloring on a glass product is prevented. <P>SOLUTION: The glass composition is an inorganic glass composition wherein the volume ratio of helium with a mass number of 3 to helium with a mass number of 4, namely<SP>3</SP>He/<SP>4</SP>He in the helium contained in the glass (at 0°C, at 1 atm) is smaller than the volume ratio<SP>3</SP>He/<SP>4</SP>He in the atmosphere. The method for producing the glass article comprises a step for melting a glass raw material by heating, a step for homogenizing the molten glass, a step for forming the molten glass into a desired shape and a step for cooling the shaped glass to room temperature, wherein helium with a certain mass ratio is contained in the glass material so that a desired glass article is obtained. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a compositionally homogeneous inorganic glass composition and a method for producing a glass article having the glass composition.

  Inorganic glass has various characteristic properties, and among them, it has been used for various applications due to advantages such as various optical functions of glass and formability that enables fine processing. For example, thin glass plates for various image display elements such as liquid crystal display element glass plates and plasma display plate glasses, various optical fibers and lens components for light related products surrounding them, and solid-state image pickup elements used for image transmission Glass for optical parts with high translucency such as cover glass, powder glass for building fine structures to ensure the reliability of image display elements such as various semiconductors and PDPs, crystallized glass and foam for building exterior wall materials A typical example thereof is a glass member for structural construction which is used regardless of the size of a large structure such as a glass building material.

  As for the production of such various glass products, technical development relating to various processing methods such as a new molding method and a polishing method has been carried out because of the necessity of accurately shaping the shape required for the application. In addition, many improvements and developments have been made on glass compositions realized by narrowing down proper properties according to required functions, and many inventions have been made accordingly. And as important as such glass shape, glass composition, etc., there is a problem of how structurally homogeneous the glass to be produced can be.

  A measure for the homogeneity of the glass depends on the size of the glass structure of interest, and the size depends on the glass application and the required quality. This scale is broadly divided into three stages academically. Among these, what is called short-range order (also called short-range structure) depending on the coordination direction of the atomic arrangement is the smallest scale, and is then composed of a combination of short-range order. The distance order, and what can be said to be a long-range order larger than this medium-range order, becomes a distance exceeding 1 nm. If a glass structure is understood as a short-range order or a medium-range order, any glass has structural features that depend on the composition, so it is difficult to express it by the concept of a structurally homogeneous state. Therefore, the concept of homogeneity is applied to the case where a dimension larger than 1 nm exceeding the medium-range order is a problem, and the concept of grasping a distance larger than a dimension generally defined as disordered as a structure. That means. In addition, the glass structure captured by these short and medium-range structures is important in describing the homogeneity of glass, but it is important to use glass on a large scale on a commercial scale. In many cases, the degree of homogeneity must be grasped.

  For example, in such a commercial scale production stage, the presence of a gas phase in the liquid phase, the presence of bubbles in the glass, is a major factor that significantly reduces the homogeneity of the glass. Moreover, even if the problem of bubbles can be avoided, depending on the glass composition, the risk of devitrification due to the precipitation of crystals from the molten glass due to the thermal history, and the two or more glass phases are different. It becomes a heterogeneous glass phase having a composition. That is, attention must be paid to the phenomenon of phase separation. Glass defects called striae, knots, streaks, and the like are as important as the factors that hinder the homogeneity and have a high risk of impairing the function of the glass. These are homogeneity disturbances in the long-range order of the glass structure caused by the bias of specific components in the glass composition.

Such heterogeneous parts in the glass, such as striae and knots, can be optically grasped, so by measuring the refractive index etc. with high accuracy, the quality of the glass is expressed and optically homogeneous. It has been defined. For example, Patent Document 1, Patent Document 2, and Patent Document 3 all indicate that the homogeneity is improved by setting such an optical refractive index within a certain range.
JP-A-6-345442 JP-A-10-265226 JP 2002-338255 A

  However, the optical homogeneity of the glass and the homogeneity of the glass composition do not necessarily coincide. For example, the refractive index of the glass used as a measure representing the optical homogeneity of the glass can be intentionally changed by adjusting the cooling conditions of the heat-formed glass. That is, even if the two glasses to be compared have different glass compositions, the refractive index of the two glasses can be changed to the same value by appropriately adjusting the cooling rate, and Even if the two glasses to be compared have the same composition, the refractive index of the two glasses can be set to different values by intentionally adjusting the stress acting constantly on the glass. Is possible. For example, commercially available optical glasses actually have different compositions with the same refractive index. Therefore, measuring only the refractive indices of the two contrasted glasses does not measure and compare the glass compositional homogeneity, but only evaluates the optical homogeneity. Absent.

  On the other hand, for various high-performance glass products that need to meet multiple high-level requirements, such as precise dimensional accuracy in addition to high chemical durability, the glass composition should be the same between the products. Management is required. For example, if a fine surface shape is to be formed on the glass surface by performing an etching process or the like, the glass surface needs to be eroded at the same etching rate. This is because the slight deviation of the glass composition caused by the decrease in homogeneity affects the amount of surface erosion caused by etching per unit time, and hinders the realization of a precise shape. . In order to avoid such a situation, in order to achieve a high level of homogeneity as a composition, not only the refractive index but also a plurality of physical properties are measured with high accuracy and realized by a chemical analysis method. Complementing the limits of precision analysis of possible glass compositions is being done.

  Further, a tracer method is used as a means for confirming uniform production conditions in the melting stage, or as one effective method for evaluating the flow characteristics of a glass melting furnace. In this method, a trace amount of a metal oxide such as cobalt oxide having a glass coloring action is added as a tracer to a glass raw material, or lead oxide that can be analyzed in a trace amount without coloring is mixed as a tracer. By evaluating how it flows out into the glass product over time, it is possible to detect the thermal history of the molten glass in the glass melting furnace and the degree of mixing by stirring, that is, the degree of homogeneity. However, the glass melting furnace is provided with only a few openings for improving the thermal efficiency during high-temperature operation, and it is difficult to contain a predetermined amount of tracer in the molten glass at an arbitrary position inside the melting furnace. In addition, there is a problem that the tracer method cannot be performed very frequently because unexpected coloration occurs in the glass product or the physical properties of the glass change due to the mixing of heavy elements.

  The present inventors can establish manufacturing conditions that can homogenize the glass in the melting stage, and can also be employed as a method for accurately evaluating the compositional homogeneity of the manufactured glass. Addressing the challenge of developing a glass composition and a method for producing the glass article that do not color the glass, etc., and presenting the results thereof.

  The glass composition of the present invention is a glass composition of inorganic glass, and the volume ratio of the isotope of mass number 3 to the isotope of mass number 4 of helium contained in the glass (0 ° C., 1 atm) is It is characterized by being smaller than the volume ratio (0 ° C., 1 atm) of a mass number 3 isotope to a mass number 4 isotope of helium present in the atmosphere.

  In general, helium (He) is sometimes classified as a rare gas or an inert gas, and its atomic structure has a closed shell structure that is structurally stable and exists as a monoatomic molecule. And this helium is the lightest element among the rare gas elements, its size is very small, the attractive force due to the Van der Waals force is very small, and it does not solidify at normal pressure even at absolute zero. It is a component exhibiting.

As for helium (He), six types of isotopes having a mass number of 3 to 8 are confirmed, but isotopes and mass numbers of mass number 4 (proton number 2, neutron number 2, electron number 2). Since the isotopes other than 3 (2 protons, 1 neutrons, 2 electrons) are unstable, it is generally well known that ⁴ He is the isotope of mass 4 and the isotope of mass 3 These are two types of ³ He. Here, an isotope is sometimes called an isotope, isotope, isotope, or isotope, but has the same number of protons (ie, atomic number) and is defined by the sum of the number of protons and a neutral number. It is a nuclide with different mass numbers of elements. In the atmosphere, the mass number 3 isotope ( ³ He) is 1 / 700,000 compared to the mass number 4 isotope ( ⁴ He), that is, 1.4 × 10 ⁻⁶ (= 1.4 ppm). Only exists. The helium contained in the glass composition of the present invention, the volume ratio (hereinafter, the volume ratio described as ³ He / ⁴ He.) For ⁴ He that ³ the He ³ value of the helium in the atmosphere Less than the value of He / ⁴ He. Thus, by containing helium in which ³ He / ⁴ He is smaller than helium in the atmosphere in the glass article, it is clearly distinguished from helium eluted from the atmosphere into the molten glass in the glass article manufacturing process. It becomes possible.

For example, helium having a ³ He / ⁴ He value different from that in the atmosphere is introduced into the molten glass, and contained in a plurality of glass bodies sampled from a desired place in the glass melting furnace or a glass article after cooling. the value of ³ He / ⁴ He measured respectively by the measurement device, mixed the value of the ³ He / ⁴ He by comparing the value of ³ He / ⁴ He in the air, the glass article in the atmosphere of helium to can be known with the ³ He / ⁴ He values ³ He / ⁴ smaller predetermined range than the value of He whether each measurement value converges. As a result, it is possible to detect the progress of the melt homogenization process in which the molten glass is homogeneously mixed in the glass melting furnace, and whether the glass article has a well homogenized composition. Can be obtained.

The value of ³ He / ⁴ He is preferably set to a smaller value in order to more easily recognize the difference from helium in the atmosphere. From such a viewpoint, the value of ³ He / ⁴ He is preferably 1.3 × 10 ⁻⁶ (0 ° C., 1 atm) or less, more preferably 1.2 × 10 ⁻⁶ (0 ° C., 1 atm) or less, more preferably 1.1 × 10 ⁻⁶ (0 ° C., 1 atm) or less, and even more preferably 1.0 × 10 ⁻⁶ (0 ° C., 1 atm) or less. And even more preferably 0.8 × 10 ⁻⁶ (0 ° C., 1 atm) or less.

The ^three values of He and ⁴ He mass number difference and ³ He / ⁴ He is, for example, since it is possible to compare and analyze by mass spectrometry or the like, so that if helium is atmospheric origin It becomes clear if it is analyzed. Furthermore, since the difference between ³ He and ⁴ He is recognized not only in the mass number but also in physical properties such as vapor pressure, the ratio of the two can be obtained by adopting an analysis method based on such a difference in physical properties. Can also be analyzed. And when mass spectrometry etc. are employ | adopted as a means to measure the isotope element amount of the mass number 3 and the mass number 4, it contains in a glass, for example by grind | pulverizing, melt | dissolving, or laser extraction etc. Helium isotopes can also be introduced into mass spectrometers and the like.

Further, the glass composition of the present invention has a volume ratio of the isotope of mass number 3 to the isotope of mass number 4 of helium contained in addition to the above in an amount of 0.8 × 10 ⁻⁶ or less (0 ° C., 1 atm). Preferably it is.

^By setting the value of ³ He / ⁴ He to 0.8 × 10 ⁻⁶ (0.8 ppm) or less, it becomes possible to evaluate the homogeneity of the glass more easily and reliably. And preferably to enhance the certainty surname, the value of ³ He / ⁴ He to a ^{1.0 × 10 -9 ~0.8 × 10 -6} . More preferably, the value of ³ He / ⁴ He is in the range of 0.5 × 10 ⁻⁸ to 0.8 × 10 ⁻⁶ , more preferably in the range of 0.5 × 10 ⁻⁸ to 5 × 10 ⁻⁷ . To do.

In addition to the above, the glass composition of the present invention has a total content of helium mass number 4 isotopes and mass number 3 isotopes of 5.0 × 10 ^{−5 to 2} μl / g (in addition to the above). 0 ° C., 1 atm) is preferable.

Helium is not involved in the formation of the glass network structure in the glass composition, but if it contains 5.0 × 10 ⁻⁵ μl / g or more in the glass composition, it can be contained in the glass by using a mass spectrometer or the like. It becomes possible to reliably specify the proportion of helium mass number 3 isotope ( ³ He) and mass number 4 isotope ( ³ He). Moreover, helium with the above content also has a function of promoting the clarification of fine bubbles remaining in the molten glass. On the other hand, when helium is contained in a large amount in the glass, there is a risk of causing reboil, particularly when it is used for the purpose of reheating the glass once formed. Therefore, the total content of helium in the glass composition is preferably 2 μL / g (0 ° C., 1 atm) or less.

  The glass composition of the present invention is preferably an oxide multicomponent glass.

  Here, the oxide multicomponent glass can be expressed as an oxide component ratio of constituent components contained therein, and is expressed as including two or more kinds of oxides. And preferably, the component which can be expressed as an oxide of the two or more components is intentionally contained by 50% or more in terms of mass% of the total amount. In addition, the case where a plurality of components are mixed as impurities in a glass composition that can be expressed by a single oxide composition does not correspond to the oxide multicomponent glass in the present invention. For example, when the content component in the glass composition is expressed by mass%, the glass composition containing a single oxide component close to 99% contains a plurality of components of 0.09 mass% or less in two digits after the decimal point. In such a case, the oxide multicomponent glass of the present invention is not applicable.

  In a multicomponent glass, it is important to bring a plurality of components into a homogeneous state in a molten glass state in order to exhibit the performance of the glass composition as designed. The oxide multicomponent glass of the present invention may contain any other component as long as it contains a multicomponent oxide as a main component. For example, a trace amount of gaseous components such as chlorine and fluorine can be mixed into the glass composition as needed.

  The glass composition of the present invention is preferably silicate glass.

Here, the term “silicate glass” refers to glass mainly composed of silica (SiO ₂ ). By applying the present invention to a silicate glass, it becomes possible to achieve a high degree of homogeneity for a glass material used in many applications.

  In addition, the glass composition of the present invention has a transmittance of 99.9% or less at a thickness of 1.0 mm with respect to a light beam having a predetermined wavelength within a wavelength range of 200.0 nm to 1050.0 nm. Is preferred.

  That is, for a light beam having an arbitrary wavelength selected from a wavelength range of 200.0 nm corresponding to ultraviolet light to 360 nm to 830 nm which is visible light, and further infrared light of 1050 nm, the glass thickness is about 1.0 mm. The transmittance is preferably in the range of 0% to 99.9%.

  And the transmittance here does not mean a measurement value by measurement in a state where a special coating or the like is applied to the glass surface, and reflection on the outer surface of the glass when a light ray enters the glass surface. The internal transmittance of the glass minus the reflection on the inner surface when the light beam is emitted from the inside of the glass, and means a value that does not depend on the surface state of the glass. However, when measuring the transmittance, it is preferable to measure the glass surface with a surface roughness Ra value of 0.5 nm or less, which is defined by a measurement value by an integrating sphere in a so-called optical mirror state. It is.

  The transmittance is a fundamental property among the optical properties of glass, but in order to make the value above the desired level, in addition to absorption and scattering phenomena due to specific components in the glass, The compositional homogeneity is an important factor. That is, it is possible to better realize the quality of the glass composition of the present invention by satisfying optical homogeneity in addition to compositional homogeneity.

  The glass composition of the present invention is preferably used by being heat sealed with a member made of one material selected from glass, ceramics and metal.

  In this case, the glass composition of the present invention is heat-sealed with the above-described member and, for example, has one function and is used as a structural member.

  The glass composition used in this application has, for example, a thin plate shape, a tubular shape, and the like, but it is the glass composition that softens and deforms when heated and sealed with the above-described member. The homogeneity of the composition of the product is important because it affects the stability of the softened shape and the chemical durability after sealing. Stable grade glass with very little difference in physicochemical properties between mass-produced glass articles with respect to the stability of the softened shape and chemical durability after sealing due to the homogeneous glass composition Articles can be obtained. The heating method here may be any method, but for example, heating by a burner, heating by an indirect electric resistance heating element, heating by infrared radiation, etc. can be adopted.

  In addition, the composition of the present invention is not limited to a thin plate shape or a tubular shape, but may take the form of powder, fine particles, granules, scales, fibers, rods, and the like. In this case, the composition of the present invention may be used in combination with other materials. For example, other materials can be added as fillers to the composition of the present invention. The type of material to be added as a filler is not particularly limited. For example, ceramic powder filler materials include titania, alumina, zirconia, silica, magnesia, zircon, barium zirconate, cordierite, lead titanate, barium titanate, mullite. Zinc oxide, tin oxide, silicon carbide, uremanite and the like can be used.

  Moreover, it is suitable for the glass composition of this invention that a crystal | crystallization precipitates inside glass and / or the glass surface.

  Here, the phrase “crystals are precipitated inside the glass and / or the glass surface” means that a plurality of inorganic crystals are precipitated inside the glass or on the glass surface.

  The type and size of the crystal are not particularly limited. Moreover, there is no problem even if a plurality of crystal seeds and a plurality of particle shapes are formed as necessary. In any case, it is preferable that the dispersed state of the crystals is dispersed without any bias. It is preferable that the dispersion of the particles is not biased at the level of long-range order because the desired mechanical properties of the glass can be realized.

  When crystals are precipitated inside and / or on the surface of the glass, the uniformity of the composition can be ensured, so that variation of the precipitated crystal species can be suppressed within a predetermined range, and the glass article can be crystallized. When used as a vitrified glass, stable strength and thermal characteristics can be realized.

  Moreover, additives, such as a clarifying agent, a decoloring agent, a coloring agent, an emulsifying agent, an oxidizing agent, a reducing agent, can be added to the glass composition of this invention. In addition, other materials that do not dissolve in the glass can be intimately mixed with the glass.

  The glass composition of the present invention can be used for various applications. For example, glass for CRT, plate glass for liquid crystal display substrate, plate glass for PDP substrate, plate glass for image display element such as plate glass for field emission display substrate, or cover glass for solid-state image sensor such as CCD and CMOS, reed switch Tube glass for electronic parts, tube glass for diodes, tube glass for xenon lamps, glass for building materials such as glass block and crystallized glass for wall materials, ampules and glass for protective windows for radiation shielding Medical glass, lighting glass such as tube glass for fluorescent lamp and liquid crystal backlight, glass for optical parts such as lens glass and ferrule for optical fiber connection, powder glass for multilayer substrate and powder glass for PDP Composite used for airtight powder glass, FRP, FRC, etc. Glass fibers such as E fibers and A fiber forming a fee.

  The method for producing a glass article of the present invention includes a step of heating and melting a glass raw material, a step of homogenizing the molten glass, a step of forming the homogenized molten glass into a predetermined shape, and a molded glass molded body. A method of manufacturing a glass article including a step of cooling to room temperature, wherein helium gas is brought into contact with the molten glass in at least one of a step of heating and melting the glass raw material and a step of homogenizing the molten glass. The volume ratio of the mass 3 isotope to the mass 4 isotope of helium (0 ° C., 1 atm) is the volume ratio of the mass 3 isotope to the mass 4 isotope of helium present in the atmosphere. Helium is contained in the glass article so as to be smaller than (0 ° C., 1 atm).

That is, a glass raw material prepared by mixing a plurality of raw materials is heated to form a molten glass, and a physical mixing operation such as stirring and bubbling is added to the molten glass to homogenize the composition of the molten glass. In a series of glass manufacturing processes, which are formed into a predetermined shape such as a plate, tube, sphere, or container by a forming method and then cooled to room temperature, a melting step in which a glass material is heated to cause a vitrification reaction to be in a molten state In any one of the above steps for homogenizing the composition of the molten glass, helium is directly brought into contact with the molten glass, and the volume ratio of helium is set to the volume ratio of helium in the atmosphere, that is, 1. Helium is contained in the glass article so as to be smaller than 4 × 10 ⁻⁶ (0 ° C., 1 atm).

The volume ratio of helium is preferably set to a smaller value in order to more accurately recognize the difference from the helium in the atmosphere. From such a viewpoint, the value of the volume ratio is preferably 1.3 × 10 ⁻⁶ (0 ° C., 1 atm) or less, and more preferably 1.2 × 10 ⁻⁶ (0 ° C., 1 atm) or less. More preferably, it is 1.1 × 10 ⁻⁶ (0 ° C., 1 atm) or less, and even more preferably, 1.0 × 10 ⁻⁶ (0 ° C., 1 atm) or less. Yes, and more preferably 0.8 × 10 ⁻⁶ (0 ° C., 1 atm) or less.

Each of the above steps may be a continuous step or an independent step. For example, the step of homogenizing the molten glass after preparing the cullet by rapidly cooling the heated and melted glass and remelting the prepared cullet may be performed by another facility. That is, means for promoting homogenization by rough melt cullet can be used in combination. Furthermore, on the extension line of this concept, it is possible to prepare a glass having a plurality of different types of compositions as a quenched glass and mix it appropriately at the stage of remelting it. In such a case, the value of ³ He / ⁴ He is intentionally different among multiple types of glass in advance, and the value of ³ He / ⁴ He in the glass obtained by mixing them is confirmed. It is also possible to confirm that homogeneous mixing has been performed.

  Moreover, about the process of heating and melting a glass raw material, what kind of method may be employ | adopted as the heating means. For example, it is possible to employ a heating method using a burner that uses liquid, gaseous fuel or the like, a heating method that uses electricity indirectly or directly, and electromagnetic waves such as infrared rays. Furthermore, natural raw materials, artificially purified products, and the like can be used as glass raw materials, and naturally glass cullet can also be used. Furthermore, various mixing operations can be employed in the step of homogenizing the molten glass. For example, stirring with a stirrer, bubbling, ultrasonic waves, etc.

  The method for containing helium in the glass article is not particularly limited, but helium gas is bubbled into the molten glass, helium is diffused by holding the helium gas above the molten glass as a molten atmosphere, and further used as a glass raw material. A predetermined amount of helium may be contained in advance in the cullet.

Further, in the method for producing a glass article of the present invention, in addition to the above, the volume ratio of the isotope of mass number 3 to the isotope of mass number 4 of helium contained is 0.8 × 10 ⁻⁶ or less (0 ° C., 1 atm), and the total content of the mass 4 isotope and the mass 3 isotope is 5.0 × 10 ^{−5 to 2} μl / g (0 ° C., 1 atm). It is suitable for inclusion in a glass article.

Whether the volume ratio of the isotope of mass 4 and the isotope of mass 3 is 0.8 × 10 ⁻⁶ or less (0 ° C., 1 atm) can determine whether the glass article has a homogeneous composition. It is suitable for. Further, helium is contained in the glass article so that the total content of the mass number 4 isotope and the mass number 3 isotope is 5.0 × 10 ^{−5 to 2} μl / g (0 ° C., 1 atm). It is preferable to increase the reliability of the calculated value based on the measurement of the volume ratio of the isotope.

In the above configuration, the molten glass may be melted and homogenized while evaluating the homogeneity of the composition by measuring the value of ³ He / ⁴ He contained in the molten glass.

  By reflecting the above evaluation results on the setting or changing of various conditions such as a glass melting facility, it is possible to employ optimum manufacturing conditions that can improve the homogeneity of the glass.

  Here, various conditions such as melting equipment include temperature, furnace atmosphere concentration, pressure, raw material charging speed, raw material adjustment conditions such as pulverization and granulation, product forming speed, bubbling speed, bubbling gas concentration, stirrer rotation speed, The amount of glass cullet used is included.

  In addition, melting and homogenization of molten glass based on the above evaluation of homogeneity, for example, adopts a method of directly connecting equipment for measuring the volume ratio to the melting equipment and reflecting the measured values in the furnace operating conditions in real time. Alternatively, a method may be employed in which the volume ratio is measured by various methods in an environment separated from the melting equipment, and the glass manufacturing conditions are changed based on the results.

Moreover, in the said structure, the process of homogenizing a molten glass is the volume ratio of the mass number 3 isotope with respect to the mass number 4 isotope of helium contained in glass in 1.0 * 10 < ^-9 > -0. It is preferable that the molten glass is homogenized so as to be 8 × 10 ⁻⁶ .

By setting the value of ³ He / ⁴ He to 1.0 × 10 ⁻⁹ or more, the presence of helium having a mass number of 3 can be reliably detected and specified, and a suitable result can be obtained. On the other hand, when the value of ³ He / ⁴ He is 0.8 × 10 ⁻⁶ or less, it can be clearly distinguished from the value of ³ He / ⁴ He contained in the atmosphere. More preferably, the value of ³ He / ⁴ He is in the range of 0.5 × 10 ⁻⁸ to 0.8 × 10 ⁻⁶ , and more preferably 0.5 × 10 ⁻⁸ to 5 × 10 6. ^-7 .

  Moreover, the manufacturing method of the glass article of this invention is not specifically limited except said point. For example, any molding method may be adopted as a method for molding glass, and a case where a glass sheet is molded, in which the molded glass may be secondarily processed by any processing means, is exemplified. In other words, a forming method such as a float method, a fusion method, a slit down method, or a roll forming method can be employed as a forming method. Various processing methods such as polishing, reed row, mechanical scribe, and laser scribe can be employed as a method for processing the plate glass after forming. Furthermore, the surface of the plate glass can be applied to various uses by applying various chemical treatments such as etching, films, functional thin films and the like.

  (1) As described above, the glass composition of the present invention is a glass composition of inorganic glass, and the volume ratio of the mass number 3 isotope to the mass number 4 isotope of helium contained in the glass ( Since the volume ratio of the isotope of mass number 3 to the isotope of mass number 4 of helium existing in the atmosphere (0 ° C., 1 atm) is smaller than, for example, molten glass melted in a melting facility As a result of measuring the volume ratio of helium isotopes in a plurality of glass sampling samples taken over time or in space, and comparing the measured values, various compositional components constituting the glass article were well managed. It can be confirmed that the thermal history has been received, or the various composition components constituting the glass article are present in the glass article evenly, and the glass composition is in a homogeneous state with no bias in the glass composition. It is possible to confirm that. Therefore, uniform properties and functions can be stably realized with respect to various properties of the glass depending on the glass composition.

(2) In the glass composition of the present invention, the volume ratio of the isotope of mass number 3 to the isotope of mass number 4 of helium contained is 0.8 × 10 ⁻⁶ or less (0 ° C., 1 atm). Since there is a clear difference from the volume ratio of helium isotopes originating from helium species present in the air, the homogeneity of the glass composition can be more easily confirmed. And by grasping | ascertaining the dispersion state of helium in glass more correctly, it is implement | achieved by the specific glass composition, The function required for the use can be achieved with high reliability.

(3) In the glass composition of the present invention, the total content of helium 4 isotope and mass 3 isotope contained is 5.0 × 10 ^{−5 to 2} μl / g (0 ° C., 1 atm), using various measuring instruments such as a mass spectrometer, the ratio of the helium 3 mass isotope ( ³ He) and the mass 4 isotope ( ³ He) in the glass article is trusted. It can be specified as a high numerical value.

  (4) The glass composition of the present invention is an oxide multicomponent glass, and if it is a silicate glass, it can be applied to a wide range of applications, for example, high-precision optical homogeneity. If it has a shape or size that makes it difficult to adopt this measurement method, even if it contains a large amount of coloring components or a glass composition that accompanies crystallization, the glass article composition can be homogenized. Confirmation is possible.

  (5) The glass composition of the present invention has a transmittance of 99.9% or less with respect to a light beam having a predetermined wavelength within a wavelength range of 200.0 nm to 1050.0 nm. In addition to the optical homogeneity specified by the homogeneity evaluation method such as refractive index, it has not only optical homogeneity but also stability as a functional material to be mounted on high performance optical related products. Various physical properties can be realized.

  (6) The glass composition of the present invention is a material having compositional homogeneity if used in a heat sealing application with a member made of one material selected from glass, ceramics and metal. Therefore, the same stable performance can be realized with respect to the shape of the sealing portion and the physical and chemical functions after sealing.

  (7) If the glass composition of the present invention is formed by precipitation of crystals inside the glass and / or the glass surface, it is difficult for fragile defect sites in the strength to occur, and excellent performance can be realized.

  (8) The method for producing a glass article of the present invention includes a step of heating and melting a glass raw material, a step of homogenizing the molten glass, a step of forming the homogenized molten glass into a predetermined shape, and molding. A method for producing a glass article including a step of cooling a glass molded body to room temperature, in at least one of a step of heating and melting a glass raw material and a step of homogenizing the molten glass, helium gas and molten glass By contacting, the volume ratio of the mass 3 isotope to the mass 4 isotope of helium (0 ° C., 1 atm) is the mass 3 isotope of the helium 4 mass isotope present in the atmosphere. If helium is contained in the glass so as to be smaller than the volume ratio of the body (0 ° C., 1 atm), the homogeneity of the composition of the molten glass is efficiently improved, It makes it possible to produce a highly functional glass utilized in people applications with a high production yield.

(9) In the method for producing a glass article of the present invention, the volume ratio of the mass 3 isotope to the helium 4 isotope contained is 0.8 × 10 ⁻⁶ or less (0 ° C., 1 atm). And helium gas is mixed with molten glass so that the total content of the isotope of mass number 4 and the isotope of mass number 3 is 5.0 × 10 ^{−5 to 2} μl / g (0 ° C., 1 atm). If it is made to contact, helium is efficiently introduced into the molten glass, so that accurate evaluation of the state of the molten glass is facilitated.

  (10) In the method for producing a glass article of the present invention, a volume ratio of a mass number 4 isotope and a mass number 3 isotope of helium contained in a molten glass, a glass molded body, or a glass article is measured. If the glass is melted and homogenized while evaluating the homogeneity by monitoring the homogeneity of the glass using the volume ratio as an index, it is possible to quickly respond to various factors in glass production. It is possible to adopt. This makes it possible to quickly produce glass articles with a high degree of homogeneity by quickly taking measures to eliminate even if glass irregularities occur at the glass production site. And

(11) In the method for producing a glass article of the present invention, the step of homogenizing the molten glass is such that the volume ratio of the mass number 3 isotope to the mass number 4 isotope contained in the glass article is 1. If the molten glass is homogenized so as to be 0 × 10 ^{−9 to} 0.8 × 10 ⁻⁶ , the variation in the performance of the glass product due to the variation in the compositional homogeneity of the glass is reduced as much as possible. The functions required by design can be realized.

  (12) Further, the glass article manufacturing method of the present invention employs a tracer that is harmless to the environment and does not color the glass article even if it is mixed in the glass article. It is suitable as a method of manufacturing while monitoring the process of making a homogeneous glass article.

  Below, the glass composition of this invention and its manufacturing method are demonstrated based on an Example.

Examples of the glass composition of the present invention are shown in Table 1. The glass composition in Table 1 is a material used for thin glass for electronic parts, thin glass for FPD, glass for radiation shielding, medical glass, glass for crystallized glass, glass fiber for FRP, and oxide. It is a multicomponent silicate glass. For each sample, a plurality of glass raw materials such as oxides are weighed in advance and mixed using a small rotary raw material mixer so as not to cause segregation of raw materials during mixing. Created. Then, this glass raw material batch is put into a platinum alloy container (platinum-rhodium 15% container) having a high temperature heat resistance and an internal volume of 1000 cc, and 1 × 10 for each glass composition in a sealed electric furnace. Melting was carried out for 16 hours under a condition (temperature from 1480 ° C. to 1600 ° C.) controlled to a temperature condition where viscosity becomes less than ³ dPa · sec. The raw material batch is melted by the high-temperature chemical reaction and the vitrification is completed. After 2 hours have passed, the cock of the gas introduction tube inserted into the closed electric furnace is released, and the isotope mass number is 4 in advance. Helium gas prepared with a volume ratio of isotope mass number 3 with respect to 1, that is, a value of ³ He / ⁴ He of 0.8 × 10 ⁻⁶ or less (for example, 1.0 × 10 ⁻⁷ ) in the furnace above the molten glass By introducing into the atmosphere, helium gas was introduced into the glass by diffusion into the molten glass. Each glass is subjected to a helium diffusion treatment for at least 5 hours, and the molten glass is homogenized by a stirring operation with a stirrer of the molten glass attached in the furnace. Thereafter, the molten glass is made of carbon. Spilled into the frame. Thereafter, this glass is held in a slow cooling furnace, and after the slow cooling operation for 2 days, the temperature is lowered to room temperature. The helium content in the obtained glass and the isotope volume ratio of mass number 4 to mass number 3 for the helium Was measured. In addition, for the confirmation of the glass composition, wet chemical analysis and instrumental analysis were performed in combination, and it was confirmed that the target composition was achieved. The above results are summarized in Table 1.

  For any measurement value, the helium measurement method is that a sample of 10 to 500 mg is taken from a glass piece cooled to room temperature, and this glass is placed in a Mo crucible of a furnace heated to 1600 ° C. and held for 20 minutes. In this method, the generated gas is vacuum-extracted and guided to a mass spectrometer, He is ionized in the apparatus, isotopes are separated by a magnetic field, ions are detected by a Faraday cup, and amplified by a multiplier tube. The apparatus used for the analysis is a double collector type noble gas mass spectrometer manufactured by Micromass. The ICP emission analyzer used for the composition analysis is SPS1500VR manufactured by Seiko Instruments Inc., which is equipped with a secondary electron multiplier (SEM) and has improved measurement sensitivity. About 0.5 g of glass was required for analysis.

From Table 1, Sample No. 1 to sample no. All the glasses up to 12 have a value of ³ He / ⁴ He in the range of 0.92 × 10 ⁻⁷ to 2.91 × 10 ⁻⁷ , and the helium content in the glass is 0.2 × 10 ^-3 μl (microliter) / g to 562.1 × 10 ⁻³ μl / g, and no decrease in the glass homogeneity found from appearance observation such as bubbles and striae was observed, and the glass composition of the present invention We were able to confirm that it was a thing.

  Next, the glass manufacturing method of the present invention will be described according to an example applied to an actual glass melting furnace. FIG. 1 shows a cross-sectional view of a glass melting furnace to which the manufacturing method of the present invention is applied. In this glass melting furnace 10, a glass raw material M of multicomponent silicate glass is continuously charged from a raw material charging machine 11 installed in the melting chamber 20, and a burner 13 and an electrode 12 disposed in the melting chamber 20. Is heated to become molten glass G. The molten glass G is homogenized by the air bubbling A in the melting chamber 20, then defoamed in the clarification chamber 30 through the throat 60, and then extended to the fork 40 from the clarification chamber 30. It is simultaneously shape | molded by 2 places of the shaping | molding part 41 of this, and another feeder shaping | molding part 42 at the plate glass. In these feeders, the molten glass G is sufficiently mixed by the provided stirrer 14. The molding amount of the glass molded body in the two molding parts 41 and 42 was approximately equal to 50 ton / day, and had the ability to enable production of 100 ton / day together. However, the glass melting furnace 10 is in a state where there is a problem in the quality of the glass article formed from the beginning of the glass production. Specifically, the foam quality of the molded part 41 is superior and the yield rate is high. In the molding part 42, the foam quality was always in a poor state.

Therefore, helium gas is disposed to blow the entire surface of the refractory R on the side wall of the melting chamber 20 under the glass raw material charging machine 11, and the helium in the helium diffusion chamber 50 is always maintained in a pressurized state. This was diffused into the molten glass G through the gaps of the refractory R or the like. Then, the value of ³ He / ⁴ He in the molding parts 41 and 42 was followed up. That is, when the time required for the value of ³ He / ⁴ He to become 0.8 × 10 ⁻⁶ or less was obtained, it took 16 hours for the molding part 41, but 13 hours for the molding part 42. It was found that there was a difference. From this, in the shaping | molding part 42, it is that the short path glass flow (it is also called a rapid flow) which melted glass G melt | dissolves sufficiently and flows out without being clarified is formed in the clarification chamber 30, the feeder 40, etc. found.

Therefore, in order to improve this phenomenon, measures were taken against a series of problems such as the temperature conditions of the melting chamber 20 and the clarification chamber 30, the glass raw material charging interval, the bubbling conditions, etc., and the foam quality in the molding section 42 was improved. Thus, the quality was inferior to that of the molded part 41. For confirmation again in this state, the same ³ He / ⁴ was subjected to measurement with respect to the value of He, forming part 41, ³ He / ⁴ value of He is 0.8 × 10 in the molten glass in the molding portion 42 ^The time required to reach ⁻⁶ or less was 15 hours for the molded part 41 and 14.8 hours for the molded part 42, confirming that the glass flow was almost the same.

As described above, it has been found that the glass manufacturing method of the present invention can improve the homogeneity of the molten glass, and by constantly introducing helium into the molten glass, the ³ He can be obtained. It has been found that tracking changes in the value of / ⁴ He makes it possible to grasp problems such as manufacturing conditions and make it suitable for manufacturing.

Next, the glass manufacturing method of the present invention was applied to a glass melting furnace having almost the same structure as FIG. 1 and having a glass production amount of 65 ton / day. Here, the gas supplied from the bubbling point in FIG. 1 is switched from air A to helium K, which has been adjusted to a value of ³ He / ⁴ He in advance, and the molten glass G is supplied from the inside of the glass melting furnace three days after switching of the bubbling gas. The ³ He / ⁴ He values of the collected glass and the glass product cooled after forming were compared. As a result, the ³ He / ⁴ He value of the molten glass in the furnace taken from the vicinity of the bubbling portion of the melting chamber 20 is 0.2 × 10 ⁻⁶ , and the ³ He of the molten glass in the furnace 60 throats before. The value of / ⁴ He was 0.3 × 10 ⁻⁶ , and the value of ³ He / ⁴ He of the product molded as plate glass was 0.2 × 10 ⁻⁶ .

Since the molten glass G in the furnace near the bubbling and the ³ He / ⁴ He value in the glass product are equal, the molten glass G that was in the furnace at the start of helium bubbling flows out as a product over the course of 3 days. It was recognized that On the other hand, it was found that the value of ³ He / ⁴ He of the molten glass G in the furnace before the throat in the furnace was relatively high, and the change in the value of ³ He / ⁴ He was delayed. In other words, it was suggested that the molten glass G did not flow out at the site before the throat and a staying region was formed, and as a result of being exposed to a high temperature environment for a long time, it may be a heterogeneous glass.

  In this glass melting furnace, plate glass for flat panel displays has been manufactured so far, but in the manufactured plate glass, the presence of inhomogeneous parts called heterogeneous glass called striae has been confirmed. Even if the cause of the problem such as low rate is clear, it is unclear what should be done and what has been done, so trial and error have been repeated. However, because the source was identified based on this result, countermeasures against the problem were taken, and after a few days, it was possible to obtain a glass state with significantly improved striae. It became possible to do.

Under stable conditions after a week has passed since the production of highly homogenous flat glass became possible, the molten glass was collected from the inside of the glass melting furnace, and the collected glass and the glass product cooled after forming ³ He / ⁴ He values were compared. As a result, it was confirmed that no deviation in the value of ³ He / ⁴ He as described above was observed, and a correlation with the homogeneity of the glass was observed. Note that the analysis of the value of Again ³ He / ⁴ He, were measured by the same mass spectrometer.

  Next, the evaluation regarding the tube glass for electronic parts used in the xenon flash lamp performed in the early stage of the present invention will be described below.

The thin tube glass used for this flash lamp is expressed in terms of mass percentage: SiO ₂ 76%, Al ₂ O ₃ 1%, B ₂ O ₃ 16% MO (M = Sr + Ca + Mg) 1%, R ₂ O (R = Na + K + Li) It is an oxide multi-component silicate glass having 6%. Since this glass is used in lamp applications, it is a material having an internal transmittance (thickness of 1 mm) of 95% to 99.9% from a wavelength of 400 nm to 800 nm. However, this glass material has a high content of boric acid, and the evaporation rate of the glass component at the time of melting is large. Therefore, heterogeneous heterogeneous glass parts such as striae are easily generated, and melting is difficult and compositional. It was pointed out that it was difficult to produce homogeneous glass.

Therefore, in order to test the present invention, helium gas whose value of ³ He / ⁴ He was adjusted in advance was introduced into the furnace by bubbling while changing melting conditions such as temperature and atmospheric conditions. And by measuring the value of ³ He / ⁴ He of this helium, it is possible to select the optimum condition among various melting conditions, and as a result, the defect rate due to striae defect that has been conventionally recognized is 2%. It was possible to improve. Incidentally, the value of ³ He / ⁴ He in the glass finally obtained, the value of ³ He / ⁴ He compared to melting in conventional atmosphere decreases, the lower limit is 0.85 × 10 ⁻⁶ (0 ° C., 1 atm).

  From the above results, the usefulness of the present invention was understood, and it became clear that it has a great effect on the production of homogeneous glass in the melting of glass.

It is explanatory drawing of the glass melting furnace which implemented the manufacturing method of this invention, Comprising: (a) is sectional drawing, (b) is a principal part top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Glass melting furnace 11 Raw material charging machine 12 Heating body 13 Burner 14 Stirrer 20 Melting chamber 30 Clarification chamber 40 Feeder 40a First feeder 40b Second feeder 41, 42 Molding part 50 Helium diffusion chamber 60 Throat A Air G Molten glass K Helium gas M Glass raw material R Refractory

Claims (12)

  A glass composition of inorganic glass, wherein the volume ratio of the isotope of mass 3 to the isotope of mass 4 of helium contained in the glass (0 ° C., 1 atm) is the mass of helium present in the atmosphere. A glass composition characterized by being smaller than a volume ratio (0 ° C., 1 atm) of a mass number 3 isotope to a number 4 isotope. 2. The glass composition according to claim 1, wherein the volume ratio of the isotope of mass number 3 to the isotope of mass number 4 of helium contained is 0.8 × 10 ⁻⁶ or less (0 ° C., 1 atm). Stuff. The total content of helium-containing isotopes of mass number 4 and mass number 3 is 5.0 × 10 ^{−5 to 2} μl / g (0 ° C., 1 atm). The glass composition of Claim 1 or Claim 2.   The glass composition according to any one of claims 1 to 3, wherein the glass composition is an oxide multicomponent glass.   It is a silicate glass, The glass composition in any one of Claims 1-4 characterized by the above-mentioned.   6. The transmittance of 1.0 mm in thickness is 99.9% or less for a light beam having a predetermined wavelength within a wavelength range of 200.0 nm to 1050.0 nm. The glass composition according to any one of the above.   The glass composition according to any one of claims 1 to 6, wherein the glass composition is heat-sealed with a member made of one material selected from glass, ceramics, and metal.   The glass composition according to any one of claims 1 to 7, wherein crystals are precipitated in the glass and / or on the glass surface. Glass including a step of heating and melting a glass raw material, a step of homogenizing the molten glass, a step of forming the homogenized molten glass into a predetermined shape, and a step of cooling the formed glass molded body to room temperature In a method for manufacturing an article,
In at least one of the step of heating and melting the glass raw material and the step of homogenizing the molten glass, helium gas is brought into contact with the molten glass, whereby a mass number of 3 isotopes with respect to a mass number of 4 isotopes of helium. So that the volume ratio of the body (0 ° C., 1 atm) is smaller than the volume ratio of the mass 3 isotope to the helium 4 mass isotope (0 ° C., 1 atm) in the atmosphere. A method for producing a glass article, which is contained in a glass article. The volume ratio of the mass 3 isotope to the helium 4 isotope contained is 0.8 × 10 ⁻⁶ or less (0 ° C., 1 atm), and the mass 4 isotope and mass number The glass according to claim 9, wherein helium is contained in the glass article so that the total content of 3 isotopes is 5.0 × 10 ^{−5 to 2} μl / g (0 ° C., 1 atm). Article manufacturing method.   Melting and homogenizing molten glass while evaluating the homogeneity by measuring the volume ratio of the helium 4 mass isotope and the mass 3 isotope contained in the molten glass, glass molding or glass article The method for producing a glass article according to claim 9 or 10, wherein the glass article is made. In the step of homogenizing the molten glass, the volume ratio of the mass 3 isotope to the helium 4 mass isotope contained in the glass article is 1.0 × 10 ^{−9 to} 0.8 × 10 ^−6. The method for producing a glass article according to any one of claims 9 to 11, wherein the molten glass is homogenized so that

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