TWI597246B - A method of producing a raw glass frit and a method of manufacturing the optical glass - Google Patents

Description

Method for producing glass raw material crude melt and method for producing optical glass

The present invention relates to a method for producing a glass material crude melt and a method for producing an optical glass.

When the glass raw material is heated and melted to produce glass, the melt causes strong erosion of the crucible. Further, the erosive force at this time is remarkable when the glass raw material is vitrified, but it is not so large after vitrification. Therefore, in the production of glass, a production method is employed in which a crude melt obtained by quenching a glass raw material after being temporarily coarsely melted is produced, and main melting is performed using the crude melt. In this production method, it is possible to suppress the erosion of ruthenium during the main melting as compared with the production method in which the glass raw material is directly used for main melting. Such a production method is used in the production of an optical glass having a large erosive force to platinum used as a ruthenium material.

Here, in the production of the crude melt, a raw material melting furnace including a quartz tube for heating and melting the glass raw material is used (see Patent Documents 1 and 2). The raw material melting furnace includes a quartz tube in which the central axis is inclined at a constant angle with respect to the horizontal direction, and a resistance heating element that heats the quartz tube. Further, when producing a coarse melt, first, a glass raw material is charged from one opening (inlet) of the quartz tube. Then, the glass raw material is moved to the other opening (flow port) side located on the lower side in the vertical direction from the inlet, and the glass raw material is heated and melted. Then, the molten glass raw material is put into a water tank disposed below the outflow port. And quenching, thereby obtaining a crude melt.

Patent Document 1: Japanese Laid-Open Patent Publication No. SHO-62-123027

<invention motivation>

However, the quartz tube used in the heating and melting of the conventional glass raw material exemplified in Patent Documents 1 and 2 is a single cylindrical tube whose inner peripheral surface is made of a smooth and non-concavo-convex surface. Therefore, when the raw material thrown into the quartz tube from the inlet is moved from the inlet side to the outlet side, the movement is not hindered at all. In other words, the raw material is heated and melted in the quartz tube, and does not stay in the quartz tube, but smoothly moves from the inlet side to the outlet side, and flows from the outlet to the water tank. Therefore, the raw material cannot be heated and melted for a long time in the quartz tube.

Therefore, when the coarse melt is produced, the heating and melting of the glass raw material becomes insufficient, and the degree of vitrification of the coarse melt is liable to lower. That is, the etch resistance of the crude melt to platinum rhodium is closer to the glass material having the lowest degree of vitrification. Therefore, compared with the glass raw material, even if the obtained crude melt has a large erosive force against platinum, coloring by platinum which is mixed by the erosion at the time of main melting is likely to occur.

In order to solve such a problem, a method of heating and melting a glass raw material in a quartz tube at a higher temperature is also considered. However, usually, optical glass contains various metals. Further, some of these metals are reduced when heated at a higher temperature, and as a result, the optical glass is sometimes colored.

<Invention purpose>

The present invention has been made in view of the above circumstances, and an object of the invention is to provide a method for producing a glass raw material crude melt capable of suppressing coloring of an optical glass produced by using a glass raw material crude melt, and an optical glass using the glass raw material crude melt. Production method.

The above problems are achieved by the following invention. which is,

The method for producing a raw material of a glass raw material according to the present invention is characterized in that a raw material supply step, a heating and melting step, and a curing step are carried out to produce a raw material for a glass raw material, which is a glass raw material from an input port of a raw material processing member. a step of supplying the raw material processing member to the raw material processing member, wherein the raw material processing member is provided with an inlet port at one end portion and an outlet port at the other end portion, and the inlet port is disposed at a position higher than the vertical direction of the outlet port. Further, the raw material processing member has a shape selected from a cylindrical shape and a groove shape, and the heating and melting step is a step of moving the glass raw material supplied into the raw material processing member from the inlet port to the outlet port and heating and melting the mixture. When the molten material of the glass raw material flowing from the outflow port is cooled and solidified, in the method for producing the glass raw material coarse melt, when the glass raw material is moved from the inlet of the raw material processing member to the outlet side, The glass raw material is temporarily retained in the raw material processing member.

In one embodiment of the method for producing a glass raw material crude melt according to the present invention, it is preferable that the glass raw material contains at least one metal selected from the group consisting of a titanium Ti compound, a ruthenium Nb compound, a tungsten W compound, a ruthenium Bi compound, and a ruthenium La compound.

Another embodiment of the method for producing a glass raw material crude melt of the present invention Preferably, the material processing member is formed of a tubular member, and the retention portion forming member for temporarily retaining the glass raw material in the tubular member is disposed to be slightly point-symmetrical with respect to the central axis of the tubular member, and In the heating and melting step, the tubular member is rotated about its central axis.

The method for producing an optical glass according to the present invention is characterized in that the glass raw material crude melt is produced by the method for producing a glass raw material crude melt of the present invention, and at least a container made of a precious metal or a precious metal alloy is obtained. The main melting process is performed in the main melting to produce an optical glass.

According to the present invention, it is possible to provide a method for producing a glass raw material crude melt which can suppress coloring of an optical glass produced by using a glass raw material crude melt, and a method for producing an optical glass using the glass raw material crude melt.

In the method for producing a glass raw material crude melt according to the present embodiment, at least a raw material supply step, a heating and melting step, and a solidification step are performed to produce a raw material for glass raw material, and the raw material supply step supplies the glass raw material to the raw material from the inlet of the raw material processing member. In the component, the raw material processing member is provided with an inlet port at one end portion and an outlet port at the other end portion, and the inlet port is disposed at a position higher than the vertical direction (in the vertical direction) of the outlet port. Further, the material processing member has a shape selected from a cylindrical shape and a groove shape; the heating and melting step moves the glass raw material supplied into the raw material processing member from the inlet port to the outlet port and heat-melts; Melting the molten glass raw material at the outlet to cool it Chemical. Here, when the glass raw material is moved from the inlet port in the raw material processing member to the outlet port side, the glass raw material is temporarily retained in the raw material processing member.

In addition, in the specification of the present application, "glass raw material" means an unvitrified raw material, that is, a batch raw material. Further, the material processing member is selected from any one of a member having a cylindrical shape (a tubular member) and a member having a groove shape (a groove member). Therefore, in the tubular member, the opening provided at one end portion serves as an input port, and the opening portion provided at the other end portion serves as an outflow port. Further, the groove-shaped member also includes a member in which a part or all of the outer peripheral surface of the tubular member is opened along the longitudinal direction of the tubular member. The opening portion of the groove-shaped member that is opened in the longitudinal direction is particularly preferably disposed so as to face the upper side with respect to the vertical direction. In this case, it is extremely easy to suppress the glass material moving from the inlet port to the outlet side in the groove-like member from falling from the groove-shaped member.

Therefore, in the method for producing a glass raw material crude melt according to the present embodiment, the glass raw material can be heated and melted for a longer period of time in the raw material processing member than in the related art. Therefore, it is possible to further increase the degree of vitrification of the coarse melt, and it is possible to suppress the coloration of the optical glass due to the erosion of the platinum crucible during main melting.

Further, in the method for producing a glass raw material crude melt according to the present embodiment, in order to further increase the degree of vitrification of the coarse melt during heating and melting of the glass raw material, the heating time can be further extended, so that it is not necessary to further increase the heating temperature. . In other words, in order to obtain the degree of vitrification similar to the coarse melt produced by the conventional method for producing a raw material of a glass raw material, the glass raw material can be added at a lower temperature and for a longer period of time. Heat melts. Therefore, even if the glass raw material contains a metal which is easy to color the optical glass by the reduction reaction at a high temperature, in the method for producing a glass raw material crude melt of the present embodiment, the optical effect caused by the reduction reaction of these metals can be easily suppressed. The color of the glass.

Examples of the metal component which is likely to cause coloring of the optical glass by the reduction reaction at a high temperature include titanium Ti, 铌Nb, tungsten W, 铋Bi, etc., among which, the coloring property to the optical glass is high or most From the viewpoint of versatility used in optical glass, examples of the metal component include titanium Ti and niobium Nb. From such a viewpoint, the glass raw material used in the method for producing a glass raw material melt of the present embodiment particularly preferably contains at least one selected from the group consisting of a titanium Ti compound, a ruthenium Nb compound, a tungsten W compound, and a ruthenium Bi compound.

Further, since the rare earth compound such as the lanthanum La compound is a component which is difficult to be melted, it is necessary to raise the melting temperature. When the melting temperature is increased, the erosion is increased or the above-mentioned easily colored metal component is reduced, so that the glass is liable to be colored. Therefore, the method for producing a glass raw material melt of the present embodiment is suitable for the production of a rare earth compound, particularly a glass raw material melt containing a lanthanum La compound. As described above, the glass raw material used in the method for producing a glass raw material melt of the present embodiment particularly preferably contains at least any selected from the group consisting of a titanium Ti compound, a ruthenium Nb compound, a tungsten W compound, a ruthenium Bi compound, and a ruthenium La compound. a metal.

In addition, in the specification of the present application, "the coloring of the optical glass" means that in the optical characteristics required for the optical glass, an undesired decrease in transmittance occurs in a predetermined wavelength band which originally has a high transmittance, and is narrowly defined. It refers to an undesired decrease in transmittance in the wavelength range of the visible region, but broadly includes a case where the wavelength range of the near-infrared region or the undesired transmittance in the wavelength region of the near-ultraviolet region is lowered.

When the glass raw material is moved from the inlet of the raw material processing member to the outflow port, the glass raw material is temporarily retained in the raw material processing member. Here, the method (retention method) in which the glass raw material is temporarily retained in the raw material processing member is not particularly limited, and for example, (1) the raw material processing member is temporarily disposed to hinder the length of the raw material processing member in the raw material processing member. A method of smoothly moving the crotch portion or the obstacle in the direction, and (2) a method of providing a concave portion as a storage portion of the glass raw material on the inner peripheral surface of the raw material processing member. Here, as an example of the dam portion, a convex portion that is provided to protrude from the inner peripheral surface is arbitrarily provided on the inner peripheral surface such that the inner diameter on the outlet side is smaller than the inner diameter on the inlet side. The layer is provided with a separator or the like of a through hole through which a molten glass raw material can pass.

Here, in the retention method of the above (1), the glass raw material moving in the raw material processing member is blocked by the crotch portion or the obstacle, and the moving speed is greatly lowered. Therefore, the glass raw material is temporarily retained in the raw material processing member. Further, in the retention method according to the above (2), the glass raw material that has moved in the raw material processing member enters the concave portion, and after the portion temporarily remains, the glass raw material that has overflowed from the concave portion moves to the outlet side again.

Next, the method for producing the glass raw material crude melt and the method for producing the optical glass according to the present embodiment will be described in detail for each step.

First, in the raw material supply step, the glass raw material is charged from the inlet of the raw material processing member. Here, as the glass raw material, as long as it contains phosphoric acid The glass raw material is not particularly limited. Further, as a component constituting the glass raw material other than phosphoric acid, ruthenium Si, ruthenium Ge, boron B, aluminum Al, zirconium Zr, lithium Li, sodium Na, potassium K, magnesium Mg, calcium Ca, strontium Sr, strontium can be used. In the manufacture of optical glass such as Ba, Ti, Ti, Nb, Zinc, Ni, G, Y, Y, T, T, In, In, C, Known raw materials for glass production such as oxides, carbonates, and hydroxides, which are various elements used. In addition, in order to ensure the clarity at the time of main melting, at least one of the components constituting the glass raw material is selected as a component which generates a gas by heating. Further, the glass raw material is usually a powdery raw material obtained by appropriately mixing various components in accordance with the composition of the produced optical glass.

When the glass raw material is supplied from the inlet of the raw material processing member to the raw material processing member, the glass raw material may be continuously supplied or may be sequentially supplied at regular intervals. In addition, the amount of the glass raw material to be supplied per unit time may be appropriately selected depending on the size and structure of the raw material processing member, the heating and melting conditions of the glass raw material, and the like.

In the heating and melting step, the glass raw material charged into the raw material processing member is heated and melted. Here, as a material constituting the raw material processing member, the crotch portion, and the obstacle, a corrosion-resistant and heat-resistant material having corrosion resistance and heat resistance to the glass raw material is used, wherein the crotch portion and the obstacle are for temporarily storing the glass raw material in the raw material treatment. Inside the part, it is placed in the raw material processing part as needed. As such a corrosion-resistant heat-resistant material, quartz glass is usually used. In addition, the raw material processing member and the crotch portion and the obstacle used as needed, as long as the portion in contact with the glass raw material in the heating and melting step is made of the corrosion resistant and heat resistant material The material composition is sufficient, but usually these members are entirely composed of a corrosion-resistant and heat-resistant material. Here, when the material processing member is composed of a tubular member, when the heating and melting step is performed, the tubular member preferably rotates appropriately with the central axis as a rotation axis. Thereby, local erosion of the inner peripheral surface of the tubular member can be prevented.

The apparatus for heating the glass raw material in the raw material processing member is not particularly limited, and a known heating device such as a resistance heating element, diesel oil, or combustion heating such as gas can be used. For example, a rod-shaped tantalum carbide SiC heater can be used. And the like is disposed around the raw material processing member. Here, the heating temperature of the glass raw material can be appropriately selected depending on the composition of the glass raw material to be used, etc., but usually, based on the liquidus temperature of the produced optical glass, it is preferably in the liquid phase based on the measurement temperature in the vicinity of the outflow port. The temperature is selected in the range of -100 degrees to the liquidus temperature + 500 degrees, and more preferably in the range of the liquidus temperature of -50 degrees to the liquidus temperature + 300 degrees.

In addition, the insertion port is disposed at a position above the vertical direction of the outlet, and the inclination angle of the central axis of the raw material processing member with respect to the horizontal direction is not particularly limited, but is usually preferably set at 1 to 30. Within the range of °. In addition, it is preferable that the glass raw material in a solid state which is put into the raw material processing member is melted substantially at the time of reaching the vicinity of the outflow port, and the heating and melting conditions such as the heating temperature and the inclination angle are set.

In the curing step, the molten glass raw material flowing from the outflow port is cooled and solidified. Thus, a crude melt of the glass raw material was obtained. The cooling method of the molten glass raw material is not particularly limited, but usually it is melted. The liquid glass material is put into water for quenching. In this case, a coarse melt of the glass raw material can be obtained. Further, in the case of water cooling, the glass raw material crude melt is taken out from the water and then dried.

Next, in order to carry out the main melting step, the raw material of the glass raw material is poured into a container made of a noble metal such as platinum, gold, a platinum alloy or a gold alloy or a noble metal alloy, for example, a crucible, a trough or a tubular container for main melting. Preferably, it is introduced into a crucible made of platinum or a platinum alloy for main melting. Then, if necessary, an optical glass is obtained by appropriately performing a post-step such as annealing, press molding, or polishing. Further, the optical glass may be a finished product such as a lens, or a semi-finished product such as a prepreg used for producing a finished product such as a lens.

Next, a specific example of the raw material melting furnace used in the method for producing a glass raw material crude melt of the present embodiment will be described with reference to the drawings.

The first figure is a schematic view showing an example of a raw material melting furnace used in the method for producing a glass raw material crude melt of the present embodiment, and specifically, a view showing a main part of the raw material melting furnace. In addition, in the first figure and the other drawings, the double arrow X direction shown in the figure indicates the horizontal direction, the double arrow Y direction indicates the vertical direction, the arrow Y1 direction indicates the upper side, and the arrow Y2 direction indicates the lower side.

The raw material melting furnace (10) shown in the first figure has a cylindrical tube (cylindrical member) (20) having an inner diameter and an outer diameter fixed in the longitudinal direction, and a rod disposed around the cylindrical tube (20). A resistor heating element (30). In addition, in the figure, a heat insulating wall disposed so as to appropriately surround a part or the whole of the cylindrical tube (20) and the resistance heating element (30) is used to monitor the melting of the raw material. Temperature sensors such as thermocouples in the vicinity of the furnace (10) or in the vicinity of the cylindrical tube (20), and other components constituting the raw material melting furnace (10) are omitted. In addition, the description of the specific structure in the cylindrical tube (20) is also omitted.

Here, the cylindrical tube (20) is disposed to be inclined such that the central axis C thereof is at a predetermined angle θ with respect to the horizontal direction. Therefore, one opening (input port (22)) of the cylindrical tube (20) is located above the other opening (outlet (24)). Further, a water tank WB filled with water is disposed below the outflow port (24). The lower limit of the above-described inclination angle θ preferably selects the minimum angle among the angles at which the melt can flow toward the outflow port (24) side in the cylindrical tube (20). Further, the upper limit of the inclination angle θ is preferably an upper limit of the angle at which all the raw materials introduced into the cylindrical tube (20) do not reach the outlet port (24) side in an unmelted state. The inclination angle θ is appropriately selected, for example, within a range exceeding 0 degrees, but is usually preferably in the range of 1 to 30 degrees, more preferably in the range of 1 to 20 degrees, and still more preferably in the range of 1 to 10 degrees. .

When the glass raw material crude melt is produced, a glass raw material (not shown) is introduced from the inlet port (22), and the glass raw material is heated and melted in the cylindrical tube (20). Further, the molten glass raw material flows from the outflow port (24) to the water filled in the water tank WB. At this time, the molten glass raw material is quenched and solidified in water to obtain a particulate glass raw material crude melt.

In addition, the specific structure in the tubular member (20) is not particularly limited as long as it can temporarily retain the glass raw material, but is used to temporarily retain the glass raw material in the retained portion of the tubular member (20). The forming member is preferably arranged to be slightly point-symmetrical with respect to the central axis C of the tubular member (20). Further, at this time, in the heating and melting step, it is preferable to make a cylindrical shape. The member (20) is rotated with its central axis as a rotation axis. In this case, the rotation of the tubular member (20) may be performed continuously or intermittently. Thereby, it is possible to prevent a part of the tubular member (20) from being more significantly corroded by the glass raw material. In addition, the cylindrical member (20) is not only provided with a function of temporarily retaining the glass raw material, but also assembled by using a commercially available single-shaped cylindrical tube and a retaining portion forming member processed into a predetermined shape. The homework is very easy. Further, by appropriately selecting the shape and size of the retention portion forming member and the arrangement position in the tubular member (20), the degree of retention of the glass raw material in the tubular member (20) can be easily controlled. Further, it is also possible to suppress the temporal change of the heat-melting treatment of the glass raw material.

In the following, a specific example of the raw material melting furnace (10) in which the retention portion forming member is disposed in point symmetry with respect to the central axis C of the tubular member (20) will be described with reference to the drawings.

The second drawing is a schematic view showing an example of a tubular member (cylindrical tube) used in the raw material melting furnace shown in the first drawing. Here, the second diagram (A) shows an example of a side view when the cylindrical tube shown in the first figure is cut in a plane including the central axis thereof, and the second diagram (B) shows the second diagram (A). An example of a plan view of the cylindrical tube shown when viewed from the outlet side.

Eight block-shaped retention portion forming members (40A) ((40)) having the same shape and size are fixedly disposed on the inner circumference of the cylindrical tube (20A) ((20)) shown in Fig. 2 . The retention portion forming member (40A) shown in Fig. 2 has a function of temporarily blocking the smooth movement of the glass material M in the longitudinal direction of the cylindrical tube (20A) as a crotch portion, and A member produced by dicing a process of cutting a cylindrical tube having an outer diameter equal to the inner diameter of the cylindrical tube (20A) (cut into a wafer) ) and get it. Further, after the cutting, in order to adjust the shape and size of the retention portion forming member (40A), the cut surface may be polished or ground as necessary.

Here, the eight retention portion forming members (40A) are arranged along the inner circumferential direction of the cylindrical tube (20A) so as to be in close contact with the inner circumferential surface (26) of the cylindrical tube (20A) with respect to the central axis C. It is located slightly closer to the outlet (24) side than the central portion of the cylindrical tube (20A). In the following description, unless otherwise specified, the arrangement position of the retention portion forming member (40) with respect to the central axis C is disposed at the position illustrated in the second diagram (A).

Further, in the example shown in the second figure, a gap W1 is formed between the two accumulation portion forming members (40A) adjacent to each other in the inner circumferential direction. The gap length (length in the circumferential direction) is a length in which the mass of the batch material cannot pass, and is, for example, preferably in the range of 0 mm to 5 mm, more preferably in the range of 0 mm to 3 mm, and still more preferably in the range of 0 mm to 1 mm. By setting the gap length to the above range, when the glass raw material M (S) in the solid state flows into the accumulation portion S, the glass raw material M (S) can be reliably left in the retention portion S. In addition, the glass raw material M (L) which is melted in the glass raw material M (S) can be temporarily retained in the retained portion S, and the glass raw material M (L) can be moved from the accumulation portion S to the outflow port (24). The side gradually flows out. In this case, by appropriately selecting the gap length or the number of the gaps W1 provided in the circumferential direction, it is possible to easily control the outflow per unit time of the glass raw material M (L) flowing out from the accumulation portion S toward the outlet port (24) side. the amount.

Moreover, as a method of fixing the retention portion forming member (40) to the inner circumference of the cylindrical tube (20), a known fixing method can be appropriately selected. For example, in the example shown in the second figure, the chemical fixing method of bonding the retention portion forming member (40A) to the inner circumferential surface (26) by an adhesive or the retention portion forming member (40A) and The inner peripheral surface (26) is a physical fixing method of welding or thermal bonding. Here, the adhesive is preferably an adhesive which is formed of the adhesive and which has heat resistance at a heating temperature of the glass raw material, is not easily reacted with the glass raw material, or is not easily melted by the glass raw material. The resulting melt erodes the same adhesive.

Further, as the fixing method, various mechanical fixing methods can also be utilized. As such a mechanical fixing method, for example, a convex portion for locking the retention portion forming member (40A) may be provided on the inner circumferential surface (26), and the retention portion forming member (40A) may be fixed by the convex portion. In this case, the retention portion forming member (40A) is disposed on the side of the convex portion where the insertion port (22) is provided with respect to the central axis C, whereby the retention portion forming member can be prevented. (40A) slips toward the outflow port (24) side due to its own weight. Alternatively, a hole may be provided in each of the inner circumferential surface (26) and the surface of the retention portion forming member (40A) opposed to the inner circumferential surface (26), and a pin may be inserted into the hole to thereby form the retention portion forming member ( 40A) is fixed with respect to the inner peripheral surface (26).

Next, an example of a heating and melting process of the glass raw material M when the glass raw material M is introduced from the input port (22) of the cylindrical pipe (20A) shown in FIG. 2 will be described.

First, the glass material M (S) in a solid state is supplied from the inlet (22) of the cylindrical tube (20A), and is placed in the vicinity of the inlet (22). On the circumference (26). At this time, the glass raw material M (S) moves toward the outflow port (24) while heating and melting. Then, the glass raw material M (L) in the molten state does not smoothly flow to the outlet (24) side along the inner peripheral surface (26), but is temporarily blocked by the retained portion forming member (40A). In addition, the glass raw material M (L) is temporarily retained in the region S0 in the vicinity of the lowermost side in the vertical direction in the region (stagnation portion S) in the vicinity of the input port (22) side of the retention portion forming member (40A).

In the retained portion S, the depth of the glass raw material M (L) is locally deepened with respect to the longitudinal direction of the cylindrical tube (20A). Here, the glass raw material M (L) retained in the accumulation portion S passes over the gap W1 between the retention portion forming members (40A) adjacent to each other in the circumferential direction, and/or over the rise of the molten metal surface. The inner peripheral surface (40AI) (the surface on the central axis C side) of the retaining portion forming member (40A) gradually flows toward the outflow port (24) side.

Further, in the state before the glass raw material M is introduced into the cylindrical tube (20), a powdery solid material is usually used, but a coarse granular solid material, a solid material in a lozenge, or these may be appropriately selected. A material or the like formed by mixing two or more materials is used. In addition, the glass raw material M retained in the retention portion S is usually preferably liquid, but is not limited thereto, and may be, for example, a state in which a solid and a liquid are mixed.

In addition, when the glass raw material M (S) in the solid state is supplied into the cylindrical tube (20), it is preferable that the glass raw material M newly introduced into the cylindrical tube (20) does not remain in the liquid in the retained portion S. The glass material M (L) is charged in a liquid level. This is because the liquid surface of the liquid glass material M (L) remaining in the retention portion S is covered with the newly-introduced glass raw material M (L). At the time of the introduction, the liquid glass material M (L) remaining in the retention portion S passes over the upper surface side of the retention portion forming member (40A), and flows out to the outlet (24) side in a large amount at a time. In this case, it is easy to vary in the process of heating and melting the glass raw material M. Further, when the molten metal flowing from the outflow port (24) is introduced into the water tank WB to obtain a coarse melt of the glass raw material, the particle diameter greatly varies.

The third drawing is a plan view showing another example of the tubular member (cylindrical tube) used in the raw material melting furnace shown in the first drawing, and specifically shows a modification of the cylindrical tube exemplified in the second drawing. Figure. Here, the plan view shown in the third figure is a plan view when the cylindrical tube is viewed from the outlet side.

Eight block-shaped retention portion forming members (40B) having the same shape and size are fixedly disposed on the inner circumference of the cylindrical tube (20B) ((20)) shown in Fig. 3 ((40)). The retention portion forming member (40B) shown in FIG. 3 has a function of temporarily blocking the smooth movement of the glass material M in the longitudinal direction of the cylindrical tube (20B), and functions as a crotch portion by A member produced by dicing a process of cutting a cylindrical tube having an outer diameter equal to the inner diameter of the cylindrical tube (20B) (cut into a wafer) ) and get it. The retention portion forming member (40B) shown in the third diagram is a member having substantially the same shape and function as the retention portion forming member (40A) shown in Fig. 2 . The eight retention portion forming members (40B) are disposed along the inner circumferential direction of the cylindrical tube (20B) in close contact with the inner circumferential surface (26) of the cylindrical tube (20B), and are mutually in the inner circumferential direction. A gap W2 is formed between the adjacent two retention portion forming members (40B).

In addition, four block members (50) are fixedly disposed on one inner circumference side of the eight retention portion forming members (40B) disposed in the cylindrical tube (20B) so as to constitute one ring. . The block member (50) is an annular member in which one cylindrical tube is cross-cut (cut into a wafer), and is equally divided into eight retaining portion forming members (40B). The shape of the part is appropriately ground and trimmed on the side of the circumference.

In the example shown in the third figure, the retention portion forming member (40B) is formed so as to constitute a partition wall that blocks the movement of the glass material M or the air in the direction of the central axis C of the cylindrical tube (20B). The block member (50) is disposed on the inner peripheral side of the cylindrical tube (20B). Further, a gap M1 is formed between the retention portion forming member (40B) and the block member (50). Further, the gap M1 has at least a size that can impede the flow of the glass raw material M(S) in a solid state.

When the amount of the glass raw material M to be charged into the cylindrical tube (20B) per unit time is small, only the retention portion forming member (40B) functions to temporarily retain the glass raw material M in the cylindrical tube (20B). The function. This is also the same for the retention portion forming member (40A) constituting the cylindrical tube (20A) shown in the second figure.

On the other hand, in the cylindrical tube (20A) shown in Fig. 2, when the amount of the glass raw material M put into the cylindrical tube (20A) per unit time is large, the solid state glass is not melted. The raw material M(S) moves over the inner peripheral surface (40AI) of the retained portion forming member (40A) and moves toward the outflow port (24) side. On the other hand, in the cylindrical tube (20B) shown in the third figure, the amount of glass raw material M input into the cylindrical tube (20B) per unit time is large. At this time, the block member (50) also functions to temporarily retain the glass raw material M in the cylindrical tube (20B). In other words, when the amount of the glass material M is large, the block member (50) can function as a crotch portion to temporarily hinder the smooth movement of the glass material M in the longitudinal direction of the cylindrical tube (20B).

The fourth drawing is a plan view showing another example of the tubular member (cylindrical tube) used in the raw material melting furnace shown in the first drawing. Here, the plan view shown in the fourth figure is a plan view when the cylindrical tube is viewed from the outlet side.

In the inner circumference of the cylindrical tube (20C) (20) shown in Fig. 4, four block-shaped retention portion forming members (40C) ((40)) having the same shape and size are fixed along the inner circumferential direction. Configuration. The retention portion forming member (40C) shown in Fig. 4 is a member produced by cutting the annular member into four equal parts in the circumferential direction, wherein the annular member is to have a circle A cylindrical tube having an outer diameter of the same size as that of the bobbin (20C) is obtained by cross-cutting (cutting into a wafer). In the retention portion forming member (40C), the surface (concave surface (40CD)) which is the inner circumferential surface of the annular member used in the formation of the retention portion forming member (40C) is opposed to the inner circumferential surface (26). In the inner circumference of the cylindrical tube (20C). Therefore, a gap G2 through which the liquid glass material M (L) can easily pass is formed between the concave surface (40CD) of the retention portion forming member (40C) and the inner circumferential surface (26). Further, between the end surface (40CS) of the two retention portion forming members (40C) adjacent to each other in the circumferential direction of the inner circumferential surface (26) and the inner circumferential surface (26), a liquid glass material M is formed ( L) A gap G3 that can be easily passed. The end surface (40CS) is a cut surface formed when the annular member used in the production of the retention portion forming member (40C) is cut.

The retention portion forming member (40C) shown in FIG. 4 functions as an obstacle that temporarily prevents the glass material M(S) in a solid state from smoothly moving in the longitudinal direction of the cylindrical tube (20C).

The material of the cylindrical tube (20), the retention portion forming member 40, and the block member (50) exemplified in the first to fourth figures is used to have corrosion resistance to the glass material M and to withstand heating of the molten glass. As the material for heat resistance at the temperature of the raw material M, quartz glass is usually used. However, when the glass material M is subjected to heat and melting for a long period of time, the material constituting the cylindrical tube (20), the retained portion forming member (40), and the block member (50) is gradually eroded. Therefore, in the retention portion forming members (40A) and (40B) illustrated in the second and third figures, the widths of the gaps W1, W2 increase with time, thereby liquid-like glass material M ( L) The function of blocking is reduced. In this case, it is difficult to temporarily retain the glass raw material M (L) in the cylindrical tubes (20A) and (20B).

In order to prevent such a problem from occurring, it is preferable that a plurality of obstructing members having the crotch portion height of the retention portion forming members (40A) and (40B) (the cylindrical tube) are densely arranged in advance in the accumulation portion S. A dimension of a fraction of a length of (20A) and (20B) in the diameter direction.

The fifth diagram is a schematic view showing an example in which a plurality of obstacle members are densely arranged in the stagnation portion S shown in the second diagram (A). Here, the fifth diagram (A) is a view showing an initial timing of the start of the heat-melting treatment of the glass raw material M, and the fifth diagram (B) is a storage portion forming member (40A) after the start of the heating and melting treatment of the glass raw material M. The erosion progresses to a certain degree of moments of the map. The obstruction member (60) shown in the fifth figure has a retention portion forming member (40A) A member having a size of a part to a tens of a degree of the height of the crotch portion is densely disposed in the retention portion S. Further, the obstruction member (60) is made of the same material as the material constituting the cylindrical tube (20), the retention portion forming member (40), and the block member (50), and as the shape thereof, for example, a spherical shape can be appropriately selected. Rod shape, polyhedral shape, cylindrical shape, etc.

Here, the function of blocking the liquid glass material M (L) in the retention portion forming member (40A) is lowered, and when the liquid surface L is largely lowered as shown in the fifth diagram (B), the liquid glass material M ( L) flows between the obstructing members (60). In this case, since the barrier members (60) are densely arranged and the gap between the barrier members (60) is extremely small, the flow resistance of the liquid glass material M(L) between the barrier members (60) is extremely large. In other words, the function of blocking the liquid glass material M (L) in the retention portion forming member (40A) is lowered, and when the liquid surface L is largely lowered as shown in Fig. 5(B), the blocking member (60) is temporarily The function of preventing the smooth movement of the glass raw material M (L) in the longitudinal direction of the cylindrical tube (20A) is hindered.

The method for producing a glass raw material crude melt according to the present embodiment described above and the method for producing an optical glass using the glass raw material crude melt are particularly suitable for the production of a phosphate-based optical glass. In the conventional method for producing a glass raw material crude melt and a method for producing an optical glass using the glass raw material crude melt, coloring is likely to occur in a phosphate-based glass composition, but the glass raw material in the present embodiment is coarsely melted. In the method for producing a material and the method for producing an optical glass using the raw material of the glass raw material, such coloring can be more effectively suppressed.

[Examples]

Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to the following examples.

(Example A1)

- Raw material melting furnace -

As the raw material melting furnace (10), the structure shown in the third figure is used in the cylindrical tube (20). The cylindrical tube (20B) and the constituent materials of the respective members disposed inside thereof are all composed of quartz glass. Here, the cylindrical tube (20B) has a size of 100 cm in length, 10 cm in outer diameter, and 8 cm in inner diameter, and the retaining portion forming member (40B) is an annular member having a thickness of 5 cm, an outer diameter of 8 cm, and an inner diameter of 6 cm. After the octant is equally divided in the circumferential direction, the shape of the member is appropriately trimmed in order to be easily placed in the cylindrical tube (20B). The gap between the two retention portion forming members (40B) disposed adjacent to each other in the cylindrical tube (20B) is about 1 mm. In addition, the block member (50) is produced by appropriately cutting an annular member having the same thickness as the annular member used in the production of the retention portion forming member (40B). Further, the retention portion forming member (40B) and the block member (50) are disposed at a position of the cylindrical tube (20B) at a distance of about 20 cm from the side of the outflow port (24). The inclination angle θ of the cylindrical tube (20B) is set to 3 degrees. Further, a thermocouple for monitoring the temperature is disposed in the vicinity of the outflow port (24) of the cylindrical tube (20B).

Further, in the stagnation portion formed by the stagnation portion forming member (40B), an obstruction member (60) composed of twenty to thirty glass sheets having an outer diameter of 10 mm to 20 mm is densely arranged. Further, the obstruction member (60) is made of the same material as the cylindrical tube (20).

As the resistance heating element (30), it will have the same function as the cylindrical tube (20B) A rod-shaped tantalum carbide SiC heater of a predetermined length is disposed in a manner slightly parallel to the cylindrical tube (20B) around the cylindrical tube (20B). Further, a water tank WB is disposed below the outflow port (24) to quench the molten metal flowing out of the outflow port (24) to obtain a glass material coarse melt (cullet).

(raw material)

A raw material (glass material MA) for producing a phosphate-based optical glass is prepared, and the raw material is composed of the following components in terms of an oxide obtained by removing a component obtained by heating and vaporizing water or carbon dioxide from a raw material. Further, in the case of blending the raw materials, orthophosphoric acid (H ₃ PO ₄ ), metaphosphoric acid or phosphorus pentoxide is used for the phosphorus pentoxide P ₂ O ₅ in each of the components shown below, and for other components, Use carbonates, nitrates, oxides, and the like.

Phosphorus pentoxide P ₂ O ₅ : 17 wt% (mass percent) yttrium oxide Nb ₂ O ₅ : 22.3 wt% yttrium oxide Bi ₂ O ₅ : 43.5 wt% tungsten oxide WO ₅ : 8.6 wt% yttrium oxide BaO: 0.7 wt% Boron oxide B ₂ O ₃ : 0.6 wt% titanium dioxide TiO ₂ : 2.6 wt% lithium oxide Li ₂ O: 0.8 wt% sodium oxide Na ₂ O: 3 wt% potassium oxide K ₂ O: 0.9 wt% total: 100 wt%

0.2wt% of the ratio of the amount of the antimony trioxide Sb ₂ O ₃ in increments to the total amount after the increase

-Manufacture of broken glass -

The cylindrical tube (20B) was heated to about 1100 degrees using a silicon carbide SiC heater. Next, the heating temperature of the cylindrical tube (20B) was maintained at 1,100 degrees, and a powdery glass raw material MA was introduced from the side of the inlet (22). Further, the glass raw material MA was charged at 1 kg every certain time interval. Further, each time the raw material MA is heated and melted, the cylindrical tube (20B) is rotated by a fixed angle with the central axis C as a rotation axis. Then, the glass raw material MA which is melted in the cylindrical tube (20B) flows out from the outlet (24) side, and is quenched in the water tank WB to obtain cullet.

-Main melting and production of optical glass -

2 kg of the obtained cullet was put into platinum crucible, and main melting was performed for about four hours at about 1100 degree, and the obtained glass was annealed in the annealing furnace, and the optical glass of the refractive index nd was 2.0027 and the Abbe number vd was 19.3 was obtained. .

(Example A2)

The following raw material melting furnace (10) is used, that is, a cylindrical tube (20) is used as the raw material melting furnace (10) except for the structure shown in the third drawing in which the obstructing member (60) is simultaneously used. In addition to the structure inside, the raw material melting furnace (10) having the same structure as the raw material melting furnace (10) used in Example A1 was provided. Here, the cylindrical tube (20C) has the same size and shape as the cylindrical tube (20B) used in the embodiment A1. Further, the retention portion forming member (40C) is formed by quarantining the annular members made of the same material as the cylindrical tube (20C) at equal intervals in the circumferential direction, and is easily disposed in the cylindrical tube (20C). The shaped parts are properly trimmed. In addition, the detention department Similarly to the embodiment A1, the forming member (40C) is disposed at a position of the cylindrical tube (20C) at a distance of about 20 cm from the side of the outflow port (24). The inclination angle θ of the cylindrical tube (20C) was set to 3 degrees in the same manner as in the example A1. Further, a thermocouple for monitoring the temperature is disposed in the vicinity of the central portion of the outer peripheral surface of the cylindrical tube (20C).

Further, cullet was produced in the same manner as in Example A1, and main melting was carried out to obtain an optical glass.

(Comparative Example A1)

The retaining portion forming member (40B), the block member (50), and the obstructing member (60) are removed from the cylindrical tube (20) in addition to the raw material melting furnace in which the raw material melting furnace (10) used in the embodiment A1 is used. In the same manner as in Example A1, cullet was produced in the same manner as in Example A1 except that the raw material melting furnace was removed, and the main glass was melted to obtain an optical glass.

(Evaluation)

With respect to the optical glasses obtained in Example A1 and Example A2, the transmittance was measured by a spectrophotometer in the range of 300 nm to 700 nm. The optical glasses of the examples A1 and A2 have optical characteristics in which the transmittance decreases from a wavelength of about 500 nm and the transmittance is almost zero at a wavelength of about 400 nm. Here, the wavelength (λ70) at which the transmittance is 70% is obtained. The results are shown in Table 1. Further, the glass obtained in Comparative Example A1 was noticeable in coloring and was not suitable as an optical glass. Thus, although the glass compositions of Examples A1, A2, and Comparative Example B1 were the same, since the preparation methods were different, glass suitable as an optical glass was obtained in Examples A1 and A2, but the glass of Comparative Example A1 was not suitable as an optical. Significant glass Colored glass.

As is clear from the results shown in Table 1, the optical glasses of Examples A1 and A2 were more likely to transmit light of a wider wavelength (difficult to be colored) in the short wavelength range of visible light than the optical glass of Comparative Example A1. Further, compared with the optical glass of Example A2, the optical glass of Example A1 easily transmitted light of a wider wavelength (difficult to color) in a short wavelength range of visible light.

(Example A3)

Instead of the cylindrical tube (20B) used in the embodiment A1, a semi-cylindrical tube obtained by substantially dividing the cylindrical tube (20B) into two portions by a plane including the central axis C is used (sixth figure The trough member (100) shown. The groove-shaped member (100) has the same dimensions and constituent materials as the cylindrical tube (20B) except that it has a structure in which the cylindrical tube (20B) is divided into two. Further, the number of the retaining portion forming members (40B) and the block members (50) disposed in the cylindrical tube (20B) is reduced to half, and is disposed in the trough member as shown in FIG. ) the inner circumference. In addition, the barrier member (60) was placed in the retention portion in the same manner as in Example A1 except that the groove member (100) was not rotated, and cullet was produced under the same conditions as in Example A1. As a result, λ70 shows a value substantially the same as that of Example A1.

(Example B1)

In the example B1, as the glass raw material M, the following A glass raw material MB for producing a phosphate-based optical glass comprising the following components. In addition, the cullet was produced in the same manner as in Example A1 except that the heating temperature of the cylindrical tube (20B) was changed to 1240 degrees, and the main glass was melted to obtain an optical glass.

Phosphorus pentoxide P ₂ O ₅ : 20 wt% (mass percent) yttrium oxide Nb ₂ O ₅ : 43 wt% yttrium oxide BaO: 19.5 wt% boron oxide B ₂ O ₃ : 3 wt% titanium dioxide TiO ₂ : 8 wt% sodium oxide Na ₂ O: 3.5 wt% potassium oxide K ₂ O: 1 wt% zinc oxide ZnO: 1 wt% zirconium dioxide ZrO ₂ : 1 wt% total: 100 wt%

Adding 0.3 wt% of the ratio of the amount of the antimony trioxide Sb ₂ O ₃ in increments to the total amount after the increase

(Example B2)

In Example B2, cullet was produced in the same manner as in Example A2 except that the glass raw material MB was used as the glass raw material MB, and the temperature of the cylindrical tube (20C) was set to be the same as in Example B1. The main melts to obtain an optical glass.

(Comparative Example B1)

In Comparative Example B1, as the glass raw material M, the glass raw material MB was used, and the temperature of the cylindrical tube was set to be the same as that of the example B1, except Further, cullet was produced in the same manner as in Example B1, and main melting was carried out to obtain an optical glass having a refractive index nd of 1.9236 and an Abbe number vd of 20.9.

(Evaluation)

The optical glass obtained in Example B1, Example B2, and Comparative Example B1 was evaluated in the same manner as the optical glass of Example A1. The results are shown in Table 2. Compared with the optical glasses of Example A1 and Example A2, the optical glasses of Example B1 and Example B2 have a low refractive index nd, and accordingly, yttrium oxide Nb ₂ O ₅ , titanium oxide TiO ₂ as a high refractive index application component, The total content of bismuth oxide Bi ₂ O ₃ and tungsten trioxide WO ₃ is small, and the glass composition is less colored. However, even if the glass composition is the same, between the examples B1 and B2 and the comparative example B1, as shown in Table 2 A large difference was observed in λ70 as a coloring index.

(10)‧‧‧Material melting furnace

(20), (20A), (20B), (20C) ‧ ‧ cylindrical tubes (tubular parts, raw material processing parts)

(22)‧‧‧ Inputs

(24)‧‧‧Exit

(26) ‧‧‧ inner circumference

(30)‧‧‧Resistive heating element

(40), (40A), (40B), (40C) ‧ ‧ stagnation forming parts

(40CD) ‧ ‧ concave

(40CS) ‧‧‧ end face

(40AI) ‧‧‧ inner circumference

(50)‧‧‧Block parts

(60) ‧‧‧blocking parts

(100)‧‧‧Semi-cylindrical tube (groove parts, raw material processing parts)

C‧‧‧ center axis

WB‧‧‧Sink

θ‧‧‧Tilt angle

X direction ‧‧‧ horizontal direction

Y direction ‧ ‧ vertical direction

Y1 direction ‧‧‧ upper side

Y2 direction ‧‧‧ lower side

The first figure is a schematic view showing an example of a raw material melting furnace used in the method for producing a glass raw material crude melt according to the present embodiment.

The second drawing is a schematic view showing an example of a tubular member (cylindrical tube) used in the raw material melting furnace shown in the first drawing. Here, the second diagram (A) shows an example of a side view when the cylindrical tube shown in the first figure is cut in a plane including the central axis thereof, and the second diagram (B) shows the second view from the outlet side. An example of a plan view of the cylindrical tube shown in Fig. (A).

The third drawing is a plan view showing another example of a tubular member (cylindrical tube) used in the raw material melting furnace shown in the first drawing.

The fourth drawing is a plan view showing still another example of the tubular member (cylindrical tube) used in the raw material melting furnace shown in the first drawing.

The fifth diagram is a schematic view showing an example in which a plurality of obstacle members are densely arranged in the stagnation portion S shown in the second diagram (A).

Fig. 6 is a plan view showing an example of a groove-shaped member (semi-cylindrical tube) used in the raw material melting furnace shown in Fig. 1 .

(10)‧‧‧Material melting furnace

(20)‧‧‧Cylindrical tubes (tubular parts, raw material processing parts)

(22)‧‧‧ Inputs

(24)‧‧‧Exit

(30)‧‧‧Resistive heating element

(C) ‧ ‧ central axis

(θ)‧‧‧Tilt angle

(WB) ‧ ‧ sink

X direction ‧‧‧ horizontal direction

Y direction ‧ ‧ vertical direction

Y1 direction ‧‧‧ upper side

Y2 direction ‧‧‧ lower side

Claims (3)

A method for producing a raw material of a glass raw material, comprising: producing a raw material of a glass raw material at least through a raw material supply step, a heating and melting step, and a curing step, wherein the raw material supply step is performed from an input port of the raw material processing member a step of supplying a glass raw material of at least one metal compound selected from the group consisting of a titanium Ti compound, a cerium Nb compound, a tungsten W compound, and a cerium Bi compound, and a phosphate raw material to the raw material processing member, wherein the raw material processing member is at one end portion The inlet port is provided, and an outlet port is provided at the other end, the inlet port is disposed at a position higher than the vertical direction of the outlet port, and the raw material processing member has a cylindrical shape and a shape selected in the groove shape, wherein the heating and melting step is a step of moving the glass raw material supplied into the raw material processing member from the inlet port to the outlet port and heating and melting, wherein the curing step is a step of cooling and solidifying a molten metal of the glass raw material flowing from the outflow port; the glass raw material coarse melt In the manufacturing method, when the glass raw material is moved from the inlet port in the raw material processing member to the outlet port side, the glass raw material is temporarily retained in the raw material processing member; The method for producing the glass raw material crude melt does not include the case where the inner peripheral surface of the raw material processing member is plated with platinum or a platinum alloy. The method for producing a raw material of a glass raw material according to the first aspect of the invention, wherein The material processing member is composed of a tubular member, and a retention portion forming member for temporarily retaining the glass material in the tubular member is disposed to be slightly point-symmetric with respect to a central axis of the tubular member. Further, in the heating and melting step, the tubular member is rotated about the central axis thereof. A method for producing an optical glass, comprising: producing a raw material of a glass raw material by using a method for producing a raw material of a glass raw material according to claim 1 or 2, and at least passing a coarse melt of the glass raw material; An optical glass is produced by performing a main melting step of main melting in a container made of a noble metal or a precious metal alloy.