TW201602044A - Near-infrared ray-absorbing glass plate - Google Patents

Abstract

Provided is a near-infrared ray-absorbing glass which can be thinned easily and can be produced steadily. A CuO-containing near-infrared ray-absorbing glass plate. The glass plate is characterized in that P2O5 is contained in an amount of 18 mol% or more and the relationships represented by the formula: (Na2O-3Al2O3)/SO3 ≥ 0.9 and the formula: P2O5/ZnO ≤ 0.8 are satisfied, wherein the contents are expressed in mol%. The glass plate is also characterized by being produced by a method comprising molding a molten glass directly or a method comprising carrying out the draw molding of a base glass while heating the base glass.

Description

Near infrared absorbing glass plate

The present invention relates to a near-infrared absorbing glass plate used in a near-infrared absorbing filter.

An infrared absorbing glass plate is used in a camera portion of a digital camera or a smart phone to correct the visual sensitivity of a solid-state imaging device such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Film Semiconductor). As the infrared absorbing glass plate, for example, a phosphate glass containing CuO is known (for example, refer to Reference 1). The infrared absorbing glass plate can cut off the light sensitivity of the near-infrared region near the absorption wavelength of 700 to 1000 nm by containing a specific amount of CuO.

In general, a near-infrared absorbing glass plate is obtained by melting a glass raw material, clarifying, homogenizing, and then casting, cooling, and then cutting into a specific shape by cutting and grinding.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2011-121792

In recent years, in order to reduce the thickness and weight of the camera, it is required to reduce the thickness of the near-infrared absorbing glass plate (for example, about 0.15 mm). However, if the near-infrared ray absorbing glass sheet is to be thinned, cracks or defects are likely to occur, and the yield tends to decrease.

In view of the above, an object of the present invention is to provide a near-infrared absorbing glass sheet which is easy to be thinned and stably produced.

The near-infrared absorbing glass plate of the present invention is characterized by containing CuO and satisfying P ₂ O ₅ 18% or more, P ₂ O ₅ /ZnO≦0.8, (Na ₂ O-3Al ₂ O ₃ ) on a molar % basis. The relationship of /SO ₃ ≧0.9 is produced by a method of directly forming molten glass or a method of extending and forming a base material glass while heating.

As a result of intensive studies, the present inventors have found that when the constituent components satisfy the above relationship in the near infrared ray absorbing glass sheet of the present invention, the method of directly forming the molten glass can be stably performed or the base material glass can be heated while extending. The method of forming is easy to be thinner. The detailed mechanism will be described below.

P ₂ O ₅ is an essential component for forming a glass skeleton, and the near-infrared absorbing glass plate of the present invention contains P ₂ O _{5 in} a specific amount or more as described above. Further, P ₂ O ₅ can be stably present in pairs with ZnO. Therefore, for the stabilization of glass, it is important to appropriately adjust the ratio of P ₂ O ₅ to ZnO. However, if the content of P ₂ O ₅ is excessive with respect to ZnO, the P ₂ O ₅ network structure is too developed, and the glass is unstable, so that the content of P ₂ O ₅ relative to ZnO is set. Below the above specific ratio, the stabilization of the glass is sought.

In addition, in the glass, Al ³⁺ can take 6 coordination positions. In addition to the presence of three covalently bonded oxygen atoms in the periphery of Al ³⁺ , there are also three non-bridged oxygen atoms. This non-bridged oxygen is considered to be due to the action of Na ⁺ ions on the oxygen atom of P ₂ O ₅ , resulting in the PO bond being cleaved. Therefore, in order to generate the above three non-bridged oxygen, three times of Na ₂ O of Al ₂ O ₃ is consumed.

On the other hand, SO ₃ can be stably present in pairs with Na ₂ O. Therefore, if the content of Na ₂ O (Na ₂ O-3Al ₂ O ₃ ) remaining after consumption in order to generate the above three non-bridged oxygen is more than the above specific ratio with respect to SO ₃ , SO ₃ and Na ₂ may be used. O exists together steadily.

As described above, the content and ratio of each component of P ₂ O ₅ , ZnO, Na ₂ O, Al ₂ O _{3 ,} and SO ₃ in the near-infrared absorbing glass plate of the present invention are regulated as described above. A method of directly forming the molten glass or a method of forming and stretching the base material glass while heating is performed stably, and the thickness is easily reduced.

The near-infrared absorbing glass plate of the present invention preferably contains SO ₃ 3% or more, Na ₂ O 5% or more, ZnO 25% or more, and Al ₂ O ₃ 0.1% or more in terms of mol%.

The near-infrared absorbing glass plate of the present invention preferably contains 0.5 to 15% of CuO in terms of mol%. Thereby, the desired near-infrared absorption characteristics are easily obtained.

The near-infrared absorbing glass plate of the present invention preferably does not precipitate crystals even when the viscosity is maintained at a temperature of 10 ^4.0 dPa ‧ for 1 hour. In general, the method of directly forming the molten glass or the method of stretching and forming the base material glass while heating is performed at a viscosity of around 10 ^4.0 dPa ‧ so that it is not required to be in the viscosity. Destruction. Therefore, it is suitable for the above-described molding method if the glass is not precipitated even if the viscosity is maintained at a temperature of 10 ^4.0 dPa ‧ for 1 hour.

The near-infrared absorbing glass plate of the present invention preferably has a thickness of 0.01 to 3 mm.

The method for producing a near-infrared absorbing glass plate of the present invention is characterized by comprising the steps of: preparing a raw material batch to obtain CuO-containing and satisfying P ₂ O ₅ 18% or more on a molar % basis, (Na ₂ O-3Al ₂ a glass having a relationship of O ₃ )/SO ₃ ≧0.9, P ₂ O ₅ /ZnO≦0.8; heating the raw material batch to obtain molten glass; and directly forming the molten glass.

The method for producing a near-infrared absorbing glass plate of the present invention is characterized by comprising the steps of: preparing a raw material batch to obtain CuO-containing and satisfying P ₂ O ₅ 18% or more on a molar % basis, (Na ₂ O-3Al ₂ a glass having a relationship of O ₃ )/SO ₃ ≧0.9, P ₂ O ₅ /ZnO≦0.8; heating the raw material batch to obtain molten glass; cooling and solidifying the molten glass to obtain a base material glass; and heating the base material glass side Extended forming.

According to the present invention, it is possible to provide a near-infrared absorbing glass which is easy to be thinned and stably produced.

Fig. 1 is a graph showing the light transmittance curve of the sample No. 1 in the examples.

Hereinafter, the range of content of each component constituting the near-infrared absorbing glass of the present invention and the reason for limitation thereof will be described. In the description of the contents of the following components, "%" means "% by mole" unless otherwise specified.

P ₂ O ₅ is an essential component for forming a glass skeleton. The content of P ₂ O ₅ is 18% or more, preferably 22% or more, more preferably 25% or more. When the content of P ₂ O ₅ is too small, the glass tends to be unstable and it tends to be difficult to form. Further, when the content of P ₂ O ₅ is too large, the glass structure is weak in chemical properties, and the weather resistance is liable to lower. Therefore, the content of P ₂ O ₅ is preferably 50% or less, more preferably 45% or less, further preferably 40% or less, and particularly preferably 30% or less.

SO ₃ has an effect of improving weather resistance and oxidizing Cu element in the glass to become Cu ²⁺ having near-infrared absorption characteristics. The content of SO ₃ is preferably 3% or more, more preferably 4% or more, still more preferably 5% or more. If the content of SO ₃ is too small, it is difficult to obtain the above effects. Further, when the content of SO ₃ is too large, the glass tends to be unstable. Therefore, the content of SO ₃ is preferably 20% or less, more preferably 15% or less, still more preferably 10% or less.

The Na ₂ O system is particularly effective for stabilizing glass. The content of Na ₂ O is preferably 5% or more, more preferably 10% or more. If the content of Na ₂ O is too small, it is difficult to obtain the above effects. Further, if the content of Na ₂ O is too large, precipitation due to crystallization of Na ₂ O, instead of the glass tends to become unstable. Moreover, weather resistance is liable to lower. Therefore, the content of Na ₂ O is preferably 20% or less, more preferably 15% or less.

ZnO is a component which is effective in stabilizing glass. Moreover, it also has the effect of improving weather resistance. The ZnO content is preferably 25% or more, more preferably 30% or more, and still more preferably 35% or more. If the ZnO content is too small, it is difficult to obtain the above effects. Further, when the ZnO content is too large, the glass tends to be unstable. Therefore, the content of ZnO is preferably 50% or less, more preferably 45% or less, still more preferably 40% or less.

Al ₂ O ₃ is a component that stabilizes glass. Moreover, it also has the effect of improving weather resistance. The content of Al ₂ O ₃ is preferably 0.1% or more, more preferably 0.5% or more, still more preferably 1% or more. If the content of Al ₂ O ₃ is too small, it is difficult to obtain the above effects. On the other hand, when the content of Al ₂ O ₃ is too large, the glass is unstable, and devitrification is likely to occur during molding. Therefore, the content of Al ₂ O ₃ is preferably 10% or less, more preferably 7% or less, further preferably 5% or less, and particularly preferably 3%.

CuO absorbs the components of near infrared rays. The content of CuO is preferably from 0.5 to 15%, more preferably from 1 to 10%, still more preferably from 3 to 9%. If the content of CuO is too small, it is difficult to obtain desired near-infrared absorption characteristics. On the other hand, when the content of CuO is too large, the light transmittance in the ultraviolet to visible range tends to decrease. Moreover, it is difficult to vitrify.

Further, the near-infrared absorption amount of the near-infrared absorbing glass plate depends on the CuO content and the thickness of the glass plate. In order to reduce the thickness of the glass sheet and achieve desired near-infrared absorption characteristics, it is preferred to increase the content of CuO.

In the near-infrared absorbing glass plate of the present invention, P ₂ O ₅ /ZnO is 0.8 or less, preferably 0.7 or less. If P ₂ O ₅ /ZnO is too large, the P ₂ O ₅ network structure is too developed, and the glass tends to become unstable. As a result, there is a tendency to be difficult to form. Further, when P ₂ O ₅ /ZnO is too small, the content of ZnO relative to P ₂ O ₅ tends to be excessive, and the glass tends to be unstable. Therefore, P ₂ O ₅ /ZnO is preferably 0.5 or more.

In the near-infrared absorbing glass plate of the present invention, (Na ₂ O-3Al ₂ O ₃ )/SO ₃ is 0.9 or more, preferably 1 or more. If (Na ₂ O-3Al ₂ O ₃ )/SO _{3 is} too small, the glass tends to become unstable. As a result, there is a tendency to be difficult to form. Further, when (Na ₂ O-3Al ₂ O ₃ )/SO _{3 is} too large, crystals due to Na ₂ O are precipitated, and the glass tends to be unstable.

The near-infrared absorbing glass plate of the present invention may contain the following components in addition to the above components.

MgO, CaO, SrO, and BaO are components that stabilize the glass. The content thereof is preferably from 0 to 10%, more preferably from 0 to 5%, still more preferably from 0.1 to 2%. However, if the content of these components is too large, the glass tends to be unstable.

Further, the content of MgO, CaO, SrO, and BaO and ZnO (RO) is preferably 25 to 50%, more preferably 30 to 45%, still more preferably 35 to 40%. If the content of RO is too small, the glass tends to be unstable. On the other hand, when the content of RO is too large, crystals such as R-NaPO ₄ or R-PO ₄ tend to precipitate, and the glass tends to be unstable.

Li ₂ O is a component that lowers the melting temperature of the glass and improves the meltability. The content of Li ₂ O is preferably from 0 to 5%, more preferably from 0.1 to 3%. When the content of Li ₂ O is too large, crystals due to Li ₂ O are likely to be precipitated during molding, and the glass tends to be unstable.

K ₂ O is a component that improves the meltability. The content of K ₂ O is preferably from 0 to 10%, more preferably from 0.1 to 7%. When the content of K ₂ O is too large, crystals due to K ₂ O are likely to be precipitated during molding, and the glass tends to be unstable.

Further, the content of R' ₂ O (R' is at least one selected from the group consisting of Li, Na and K) is preferably from 5 to 20%, more preferably from 8 to 18%, still more preferably from 10 to 15%. . When R _'2 O of the content is too small, the glass tends to become unstable. On the other hand, when the content of R' ₂ O is too large, crystals of R'-form tend to precipitate during molding, and the glass tends to be unstable.

CeO ₂ and Sb ₂ O ₃ have an effect of suppressing reduction of Cu ²⁺ ions by lowering the melting temperature and improving near-infrared absorption characteristics. The content of CeO ₂ and Sb ₂ O ₃ is preferably from 0 to 0.5%, more preferably from 0.1 to 0.3%. If the content of these components is too large, the glass tends to be unstable.

Nb ₂ O ₅ is a component that improves weatherability. The content of Nb ₂ O ₅ is preferably from 0 to 3%, more preferably from 0 to 2%. When the content of Nb ₂ O ₅ is too large, the meltability is lowered and the melting temperature tends to be high. As a result, Cu ²⁺ ions are easily reduced, and it is difficult to obtain desired spectral characteristics.

Y ₂ O ₃ and La ₂ O ₃ are components which stabilize the glass. The content of Y ₂ O ₃ and La ₂ O ₃ is preferably 0 to 3%, more preferably 0 to 2%. When the content of Y ₂ O ₃ or La ₂ O ₃ is too large, devitrification is likely to occur at the time of molding. Further, the refractive index becomes high, the surface reflection becomes large, and the light transmittance in the visible range tends to decrease.

Ta ₂ O ₅ is a component that enhances chemical durability. The content of Ta ₂ O ₅ is preferably from 0 to 3%, more preferably from 0 to 2%. If the content of Ta ₂ O ₃ is too large, devitrification is likely to occur at the time of molding. Further, the refractive index becomes high, the surface reflection becomes large, and the light transmittance in the visible range tends to decrease.

In the present invention, since B ₂ O ₃ is a component which makes the glass unstable, the content thereof is preferably 3% or less, more preferably 2% or less.

Further, the Cl component is preferably not contained in consideration of the influence on the human body. Further, since Ag ₂ O can affect the valence of the Cu element, it is preferably not contained.

Further, when a large amount of U component or Th component as an impurity is contained in the raw material, α rays are released from the glass plate. Therefore, in the use of the opacity correction filter or the color adjustment filter, there is a problem that the CCD or CMOS signal is defective due to the alpha ray. Therefore, the content of U and Th in the near-infrared absorbing glass plate of the present invention is preferably 1 ppm or less, more preferably 100 ppb or less, still more preferably 20 ppb or less. Further, the amount of α rays emitted from the near infrared absorbing glass plate of the present invention is preferably 1.0 c/cm ² ‧ h or less.

The near-infrared absorbing glass plate of the present invention can maintain high transmittance in the visible range and sharply cut light in the near-infrared region. Specifically, it is preferable that the transmittance at a wavelength of 500 nm is 80% or more (and further 82% or more) at a wavelength of 500 nm to 1200 nm in which the wavelength (λ ₅₀ ) of 50% transmittance is 615 nm. Further, the transmittance at a wavelength of 1100 nm is 25% or less (and further 15% or less).

The near-infrared absorbing glass plate of the present invention is characterized in that it is formed by directly forming a molten glass or by stretching a base material glass while heating it. Specifically, the near-infrared absorbing glass plate of the present invention is preferably produced by a method of directly forming a molten glass by a pulling method, a rollout method, a direct pressing method or a floating method. Further, it is preferably produced by a re-drawing method in which a base material glass is heated and formed by one side. When the glass composition is adjusted as described above, even in the case of the molding method in which devitrification is likely to occur at the time of molding as described above, occurrence of devitrification can be suppressed, and near-infrared absorbing glass having desired characteristics can be obtained. board. Examples of the pull-down method include an overflow down-draw method, a flow-down method, and the like. The overflow down method is the following method: making it self-contained The molten glass overflowing from the upper portion of the body flows down the both sides of the formed body, is fused at the lower portion of the formed body, and is stretched and formed below, thereby obtaining a plate-shaped glass. The orifice down-draw method is a method in which a molten glass is discharged from a substantially rectangular gap provided at the bottom of a molded body, and is stretched and formed under the surface to obtain a plate-shaped glass.

In particular, when the near-infrared absorbing glass plate of the present invention is formed by an overflow down-draw method or a re-drawing method, the surface is a flame-polished surface, and the surface quality is good, which is preferable. In this case, it can also be used as a product in a state where the surface is not ground. Moreover, in the case of the overflow down-draw method, it is easy to thin or enlarge the glass plate. Further, the orifice down-draw method is also a method in which the thickness of the glass sheet can be easily reduced. Therefore, the flow hole down-draw method can also be employed in the case where the surface quality is less required and the glass plate is made thinner.

The near-infrared absorbing glass plate of the present invention preferably does not precipitate crystals even when the viscosity is maintained at a temperature of 10 ^4.0 dPa ‧ for 1 hour. Therefore, it is difficult to devitrify when applying a method of directly forming molten glass or a method of forming a base material glass while heating and extending it.

The thickness of the near-infrared absorbing glass plate of the present invention is preferably from 0.01 to 3 mm, more preferably from 0.05 to 2 mm, still more preferably from 0.1 to 1.5 mm. If the thickness of the near-infrared absorbing glass plate is too small, it is easily broken. On the other hand, if the thickness of the near-infrared absorbing glass plate is too large, it may become difficult to reduce the thickness and weight of the optical device.

The near-infrared absorbing glass plate of the present invention can be produced in the following manner.

First, the raw material batch is adjusted in such a way as to achieve the desired composition. Specifically, a raw material batch is prepared to obtain CuO-containing and satisfying P ₂ O ₅ 18% or more on a molar % basis, (Na ₂ O-3Al ₂ O ₃ )/SO ₃ ≧ 0.9, P ₂ O ₅ / Glass with a relationship of ZnO ≦ 0.8.

Then, the raw material batch is heated to obtain molten glass. The melting temperature is preferably about 600 to 1000 °C. If the melting temperature is too low, it is difficult to obtain a homogeneous glass. On the other hand, if the melting temperature is too high, Cu ²⁺ ions are easily reduced, and it is difficult to obtain desired spectral characteristics.

Further, the near-infrared absorbing glass plate of the present invention is obtained by a method of directly forming molten glass or a method of extending and molding a base material glass while heating. Can also form The subsequent glass plate is appropriately subjected to a cutting process, or an infrared region wavelength absorbing film is formed on the surface.

[Examples]

Hereinafter, the near-infrared absorbing glass plate of the present invention will be described in detail based on examples, but the present invention is not limited to the examples.

Tables 1 and 2 show examples (Nos. 1 to 9) and comparative examples (Nos. 10 to 14) of the present invention.

(1) Production of samples

Each sample was produced in the following manner. First, the raw material batch blended so as to have the composition described in each table is put into a platinum crucible, and is melted at 700 to 900 ° C in a homogeneous manner. As raw materials, use aluminum metaphosphate, zinc metaphosphate, orthophosphate, zinc sulfate Heptahydrate, zinc sulfate anhydrate, sodium sulfate, calcium carbonate, total carbonic acid, and the like. Then, the molten glass was discharged to a carbon plate, cooled and solidified, and annealed to prepare a sample.

The light transmittance curve of the sample No. 1 is shown in Fig. 1. In addition, the light transmittance was measured by using a UV3100PC manufactured by Shimadzu Corporation, which was obtained by mirror-polishing both surfaces of a diamond powder having a particle size of 0.5 μm.

(2) Evaluation of resistance to devitrification

For the obtained sample, the devitrification resistance at 10 ^4.0 dPa ‧ was evaluated by the following method.

The sample was pulverized and placed in a crucible made of platinum. Then, the platinum crucible was heated to make the sample into a molten state, and the viscosity of the glass at a plurality of temperatures was determined by a platinum ball pulling method. Thereafter, a viscosity curve was prepared based on the obtained plurality of measured values, and the viscosity was set to a temperature of 10 ^4.0 dPa‧s by interpolation.

The pulverized sample is placed in a platinum crucible corresponding to 100 cc, heated at 600 to 900 ° C for 30 minutes, and cooled for 5 to 10 hours until the calculated viscosity becomes 10 ^4.0 dPa ‧ and then Hold at temperature for 1 hour. Using an optical microscope, it was confirmed whether the inside of the glass and the interface between the glass and the crucible were devitrified. When the unrecognized person is evaluated as "○", it is confirmed that the person who has lost the opacity is evaluated as "X".

(3) Investigation of the results

It is understood that the samples of Nos. 1 to 9 which are examples are not devitrified even when the viscosity is maintained at a temperature of 10 ^4.0 dPa ‧ for 1 hour, and it is suitable for a method of directly forming molten glass or a base material. A method in which the glass is heated and stretched on one side. On the other hand, as a sample of Comparative Examples No.10 ~ 12 the viscosity becomes to devitrification in the holding case 1 hour at a temperature of 10 ^4.0 dPa‧s, therefore considered difficult to apply the above-described forming method. Further, samples of Nos. 13 and 14 as comparative examples were not vitrified.

[Industrial availability]

The near-infrared absorbing glass plate of the invention can be used for lens of digital camera, CCD cover glass, heat absorbing glass plate used for CCD or CMOS, and further IR (Infra-red, infrared Line)/UV (Ultraviolet) absorbs optical filters such as glass plates, visual sensitivity filters, and color adjustment filters.

Claims (7)

A near-infrared absorbing glass plate characterized in that it contains CuO and satisfies P ₂ O ₅ 18% or more, (Na ₂ O-3Al ₂ O ₃ )/SO ₃ ≧ 0.9, P ₂ on a molar % basis. The relationship of O ₅ /ZnO≦0.8 is produced by a method of directly forming molten glass or a method of extending and forming a base material glass while heating. The near-infrared absorbing glass plate of claim 1 which contains, by mole %, SO ₃ 3% or more, Na ₂ O 5% or more, ZnO 25% or more, and Al ₂ O ₃ 0.1% or more. A near-infrared absorbing glass plate according to claim 1 or 2, which contains 0.5 to 15% of CuO in mole %. The near-infrared absorbing glass plate according to any one of claims 1 to 3, which does not precipitate crystals even if the viscosity is maintained at a temperature of 10 ^4.0 dPa ‧ for 1 hour. The near-infrared absorbing glass plate according to any one of claims 1 to 4, which has a thickness of 0.01 to 3 mm. A method for producing a near-infrared absorbing glass plate, comprising the steps of: preparing a raw material batch to obtain CuO-containing and satisfying P ₂ O ₅ 18% or more on a molar basis, (Na ₂ O-3Al ₂ O ₃ ) glass having a relationship of /SO ₃ ≧ 0.9, P ₂ O _{5 /} ZnO ≦ 0.8; heating the raw material batch to obtain molten glass; and directly forming the molten glass. A method for producing a near-infrared absorbing glass plate, comprising the steps of: preparing a raw material batch to obtain CuO-containing and satisfying P ₂ O ₅ 18% or more on a molar basis, (Na ₂ O-3Al ₂ O ₃ ) a glass having a relationship of /SO ₃ ≧0.9 and P ₂ O ₅ /ZnO≦0.8; heating the raw material batch to obtain molten glass; cooling and solidifying the molten glass to obtain a base material glass; and The heating is extended and formed.