JP5656040B2 - Li2O-Al2O3-SiO2 based crystallized glass - Google Patents

Description

The present invention relates to a Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass.

Crystallized glass is used in various applications because it has high mechanical strength and is easy to process. For example, Patent Documents 1 to 3 primary crystals as β- quartz solid solution _{(Li 2 O · Al 2 O} 3 · nSiO 2 [ provided that n ≧ 2]) and β- spodumene solid solution _{(Li 2 O · Al 2 O} 3 · nSiO ₂ [where n ≧ 4]) is disclosed, and Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass is disclosed, for front windows such as petroleum stoves and wood stoves, for color filters and image sensors It is used for substrates for high-tech products such as substrates, setters for firing electronic components, shelf plates for microwave ovens, top plates for electromagnetic cooking, window glass for fire doors, reflectors, and the like.

The Li ₂ O—Al ₂ O ₃ —SiO ₂ crystallized glass described above has excellent thermal characteristics because it has a low coefficient of thermal expansion and high mechanical strength. In addition, since the precipitated crystals can be changed by changing the heat treatment conditions in the crystallization process, transparent crystallized glass (β-quartz solid solution is precipitated) and white opaque crystallized glass ( Both of β-spodumene solid solution can be produced and can be used properly according to the application.

  Similar to general glass manufacturing, glass recovered from the market is reused as a raw material (cullet) from both the environmental and manufacturing aspects in the manufacturing of crystallized glass. In recent years, with the spread of electromagnetic cookers, the shipment amount of crystallized glass top plates for cookers has increased, and the amount of cooker top plates recovered from the market has also increased.

As disclosed in Patent Documents 4, 5, 6, and 7, most of the top plates for cookers have a decorative layer or a light-shielding layer containing an inorganic pigment formed on a crystallized glass plate. And has an excellent aesthetics. Oxides such as Fe, Ni, Cr, Co, and Mn are used as main components of the inorganic pigment.
Japanese Examined Patent Publication No. 39-21049 Japanese Patent Publication No. 40-20182 JP-A-1-308845 JP 2003-168548 A JP 2003-338360 A US Patent Application Publication No. 2003/006231 JP-A-8-165143

When a cooker top plate made of Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass decorated with an inorganic pigment is crushed as it is and used as a glass raw material, the glass is colored, and further, crystallized glass and For this reason, when crystals are precipitated, the components of the inorganic pigment are concentrated in the glass matrix, so that there is a problem that coloring becomes strong.

  In addition, since the decorative layer and the light shielding layer containing an inorganic pigment are firmly bonded with glass frit or the like, it is very troublesome to separate the crystallized glass plate from the decorative layer and the light shielding layer.

An object of the present invention is to provide Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass with less coloring without effectively using glass collected from the market.

As a result of intensive studies, the present inventor has found that even if the inorganic pigment component is mixed in the glass to some extent, even if the glass is crystallized by appropriately controlling the content of TiO ₂ , ZnO and MgO, the inorganic pigment The present inventors have found that coloring due to can be suppressed and propose as the present invention.

That is, the Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass of the present invention is 1.5 to 4.3% of TiO ₂ + MgO + ZnO, and TiO ₂ / (TiO ₂ + MgO + ZnO) is 0. _{2 to} 0.9, Fe ₂ O ₃ is 50 to 500 ppm, Fe ²⁺ / total Fe is 90% or less, CoO + Cr ₂ O ₃ + NiO + MnO is 5 to 100 ppm, CoO + NiO is 0 to 70 ppm , Fe ²⁺ / total Fe is a is that _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass obtained by heat-treating 90% or less of crystalline glass, a ^* value at 4mm thickness L ^* a ^* b ^* color system It is characterized in that −2 to 2 and b ^* value is −10 to 20.

The Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass of the present invention is 50 to 500 ppm Fe ₂ O _{3, 5} to 100 ppm CoO + Cr ₂ O ₃ + NiO + MnO, and 0 to 60 ppm CoO + NiO in terms of mass. Despite containing coloring components, a white opaque or colorless and transparent material can be obtained by appropriately controlling the contents of TiO ₂ , ZnO and MgO. Specifically, when the thickness is 4 mm, the a ^* value of the L ^* a ^* b ^* color system can be -2 to 2, and the b ^* value can be -10 to 20. In particular, the effect is great for crystallized glass having a crystallinity of 60% by mass or more.

That is, the valence and coordination state of colored ions (here, ions of Fe, Ni, Cr, Co, Mn, etc.) that are concentrated in the glass matrix after the crystals are precipitated are expressed as TiO ₂ , ZnO, and MgO. By controlling, coloring of the crystallized glass caused by colored ions is suppressed.

  Hereinafter, the present invention will be described in detail.

  The percentages and the like in the present invention are based on mass unless otherwise indicated.

The Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass of the present invention contains TiO ₂ as an essential component in addition to SiO ₂ , Al ₂ O ₃ and Li ₂ O, and β-quartz A solid solution (β-eucryptite solid solution) is precipitated.

Further, Fe ₂ O ₃ is contained as an impurity component from the glass raw material or cullet, and in addition, at least one impurity selected from the group of NiO, Cr ₂ O ₃ , CoO and MnO is included.

If you try to less than 50ppm and the content of Fe ₂ O _3, it is necessary to use a cullet removal of the coating, such as a raw material or a coloring layer such as a less expensive silica sand and feldspar of the content of Fe ₂ O ₃ Contrary to the object of the present invention. On the other hand, if it exceeds 500 ppm, it is difficult to make the b ^* value -10 to 20 even if the content of TiO ₂ , ZnO and MgO is appropriately controlled. A preferable range of Fe ₂ O ₃ is 110 to 450 ppm, and a more preferable range is 170 to 400 ppm.

If the total amount of CoO, Cr ₂ O ₃ , NiO, and MnO is to be less than 5 ppm, the amount of untreated cullet to be used must be reduced or a coating such as a colored layer must be removed. Contrary to On the other hand, if it exceeds 100 ppm, it is difficult to make the a ^* value from −2 to 2 even if the contents of TiO ₂ , ZnO and MgO are controlled appropriately. A preferable range of the total amount of CoO, Cr ₂ O ₃ , NiO, and MnO is 5 to 90 ppm, and a more preferable range is 15 to 80 ppm.

CoO and NiO are particularly strongly colored components. If the total amount is more than 60 ppm, the a ^* value should be -2 to 2 even if the content of TiO ₂ , ZnO and MgO is appropriately controlled. Is difficult. Preferably it is 50 ppm or less.

When the crystallized glass of the present invention is Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass, it has excellent thermal characteristics because it has a low coefficient of thermal expansion and high mechanical strength. In particular, when the main crystal is a β-quartz solid solution, a transparent crystallized glass can be obtained, so that it can be used for various applications. The average visible light transmittance at a wavelength of 380 to 780 nm is 65% at a thickness of 5 mm. If it is above, it can be used as a window material if it is 8 mm or less. More preferably, it is 75% or more, and a further preferable range is 80% or more.

In the case of Li ₂ O—Al ₂ O ₃ —SiO ₂ based crystallized glass, TiO ₂ is a nucleating agent, and ZnO and MgO are constituents of crystals, but these components remain in the glass matrix. Affects the valence and coordination state of the colored ions. In terms of mass%, TiO ₂ is 0.3 to 3%, TiO ₂ + MgO + ZnO is 1.5 to 8%, and TiO ₂ / (TiO ₂ + MgO + ZnO) is 0.2 to 0.9, TiO ₂ , MgO And a part of ZnO is taken in and consumed by the crystal, and TiO ₂ , MgO and ZnO remain in an appropriate amount in the glass matrix after crystallization, so that coloring of ions such as Fe, Co, Cr, Ni and Mn is weakened Coloring is suppressed by taking such a valence and coordination state.

TiO ₂ is called a nucleating agent and is a component added so that crystals are uniformly precipitated in glass. If TiO ₂ is less than 0.3%, crystals are difficult to precipitate uniformly, There is a risk of breakage due to thermal strain caused by variation in expansion coefficient. On the other hand, if it exceeds 3%, a large amount of TiO ₂ remains in the glass matrix after crystallization, and on the contrary, coloring may be strengthened rather than suppressing coloring of the crystallized glass by colored ions. A more preferable range of TiO ₂ is 0.3 to 2.5%, and a further preferable range is 0.3 to 1.9%.

When the total amount of TiO ₂ , MgO, and ZnO is less than 1.5%, the valence and the coordination state tend to increase the coloring of the colored ions present in the glass matrix, and the coloring becomes easy. On the other hand, if it exceeds 4.3 %, the total amount of TiO ₂ , MgO, and ZnO remaining in the glass matrix increases, and the basicity of the glass matrix increases. If it intensifies the coloring there Ru to.

When TiO ₂ / (TiO ₂ + MgO + ZnO) is smaller than 0.2, there is a tendency that a valence or coordination state that controls the coloring of the colored ions present in the glass matrix tends to be difficult, and coloring is difficult to suppress. On the other hand, when it is larger than 0.9, as in the case where it is smaller than 0.2, there is a tendency that the valence and coordination state that controls the coloring of the colored ions existing in the glass matrix tend to be difficult, and the coloring is suppressed. Hard to do. A more preferable range of TiO ₂ / (TiO ₂ + MgO + ZnO) is 0.3 to 0.85.

  MgO and ZnO are components that form crystals by solid solution in β-quartz solid solution or β-spodumene solid solution, and are components that lower the viscosity of glass, and their total amount is 0.3 to 7%. Preferably there is. If it is less than 0.3%, it is difficult to sufficiently lower the viscosity of the glass, so that it tends to be difficult to melt or mold the glass. If it is more than 7%, the glass matrix after crystallization tends to be difficult. A large amount of MgO or ZnO remains, and rather than suppressing the coloring of the crystallized glass by the colored ions, the coloring may be strengthened. A preferable range of the total amount of MgO and ZnO is 0.3 to 6%, and a more preferable range is 0.3 to 5%.

Further, Sb ₂ O ₃ added as a fining agent has an effect of enhancing the coloring of impurities such as Fe. Therefore, the content of Sb ₂ O ₃ is preferably 3% or less. A preferred range for Sb ₂ O ₃ is 2% or less, and a more preferred range is 1.4% or less.

ZrO ₂ or P ₂ O ₅ is used as a nucleating agent for promoting crystal precipitation. If ZrO ₂ is 0.5 to 7%, TiO ₂ , MgO, and ZnO are easily taken into the crystal, and the concentration of TiO ₂ , MgO, and ZnO in the glass matrix becomes an appropriate amount, so that it is difficult to color impurities. Become. A preferable range of ZrO ₂ is 0.8 to 6%.

Although P ₂ O ₅ is less effective than ZrO _{2, it} has the effect of promoting crystal precipitation. A preferable range of P ₂ O ₅ is 0 to 10%, a more preferable range is 0.02 to 8%, and a further preferable range is 0.1 to 6.9%. If it exceeds 10%, the glass tends to phase-separate at the time of melting.

When the flux component of Na ₂ O or K ₂ O is reduced, the basicity of the glass is lowered and impurity coloring may be reduced. Therefore, Na ₂ O + K ₂ O is preferably 4% or less. A preferred range is 3% or less, and a more preferred range is 1.4% or less.

  Halogen (F, Cl, Br, I) has an effect of enhancing coloring. Therefore, it is preferable that substantially no halogen is added except for the inevitable mixing from the raw materials.

As components other than the above, the SiO ₂ 61 to 67%, the Al ₂ O ₃ 19~24%, the Li ₂ O 3.2~4.4%, preferably contains from 0 to 1.4% of BaO .

In particular, Li ₂ O is an important component because it has a large effect on crystallinity. If the Li ₂ O content is less than 3.2%, the crystallinity is lowered, the thermal expansion is increased, and the thermal shock resistance is lowered. In addition, TiO ₂ is less likely to be precipitated, and impurity coloring in the glass phase tends to be strong. When Li ₂ O is larger than 4.5%, thermal expansion is reduced and precipitation of TiO ₂ is promoted, but Li ₂ O itself tends to remain in the glass phase, the basicity of the glass is increased, and impurity coloring is increased. Since it becomes strong, it is not preferable. A more preferable range of Li ₂ O is 3.5 to 4.3%, and a further preferable range is 3.7 to 4.3%.

SiO ₂ is a component that forms a glass skeleton and constitutes a crystal. If SiO ₂ is less than 61%, thermal expansion becomes too large, which is not preferable. If it exceeds 67%, glass melting becomes difficult.

Al ₂ O _{3 is} also a component that forms a glass skeleton and constitutes crystals. If it is less than 19%, it tends to be devitrified and glass chemical durability is lowered, which is not preferable. If it exceeds 24%, the viscosity of the glass becomes too high and glass melting becomes difficult.

BaO has an effect of enhancing the coloring of impurities such as Fe, although not as much as Sb ₂ O ₃ . Therefore, it is preferable to set it as 1.4% or less.

When the crystallized glass of the present invention is produced by heat-treating a crystalline glass having an Fe ²⁺ ratio (Fe ²⁺ / total Fe) of 90% by mass or less, it is difficult to color. The coloring of the crystallized glass with Fe, Co, Cr, Ni, and Mn has a correlation with the redox atmosphere of the crystalline glass. The stronger the oxidizing atmosphere of the crystalline glass, the weaker the coloring. The strength of the oxidizing atmosphere of the crystalline glass can be expressed by using the Fe ²⁺ ratio (Fe ²⁺ / total Fe) as an index. That is, it can be judged that the ratio of Fe ^{2+ as} a reductant is low and the oxidizing atmosphere of the glass is strong. A preferable range of the Fe ²⁺ ratio (Fe ²⁺ / total Fe) is 85% by mass or less, and a more preferable range is 70% by mass or less.

In addition, as a method of setting the Fe ²⁺ ratio (Fe ²⁺ / total Fe) in the crystalline glass to 90% by mass or less, the content of TiO ₂ , MgO, and ZnO is controlled (in terms of mass%, TiO ₂ Is 0.3 to 3%, TiO ₂ + MgO + ZnO is 1.5 to 8%, TiO ₂ / (TiO ₂ + MgO + ZnO) is 0.2 to 0.9), and does not contain a reducing agent such as carbon or metal. It is necessary. Furthermore, it is preferable to use low-temperature melting of glass, addition of an oxidizing agent such as nitrate at the time of melting, and the like.

As conditions for heat-treating the crystalline glass, the nucleation treatment temperature (primary treatment temperature) is 600 to 800 ° C., the nucleation treatment time (primary treatment time) is 0.2 to 5 hours, and the crystal growth treatment temperature ( (Secondary treatment temperature) is 830 to 910 ° C., and the crystal growth treatment time (secondary treatment time) is 0.1 to 3 hours. When the crystal growth treatment is performed after the nucleation treatment, TiO ₂ , MgO, ZnO Tends to be taken into the crystal, and the concentration of TiO ₂ , MgO, and ZnO in the glass matrix becomes an appropriate amount, so that coloring is easily reduced.

  The crystallized glass of the present invention will be described in detail using examples and comparative examples.

Tables 1 to 3 show examples, reference examples, and comparative examples of the present invention.

First, a glass raw material containing sodium, potassium and barium nitrates was prepared so as to have the composition shown in the table, and the prepared glass raw material was melted at 1550 to 1750 ° C. for 4 to 40 hours, then molded, and Li ₂ O— An Al ₂ O ₃ —SiO ₂ crystalline glass was obtained. Since Example 5 does not contain BaO, barium nitrate was not used. Moreover, the comparative example 6 melted at 1750 degreeC using the glass raw material which contained 0.5% of carbon without using nitrate as a raw material.

Subsequently, the formed body made of the crystalline glass is held at 700 to 800 ° C. for 1 to 4 hours for nucleation, and heat treated at 800 to 950 ° C. for 0.5 to 3 hours to precipitate β-quartz solid solution. Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass was obtained.

As apparent from Tables 1 to 3, Examples 1 to 3 and 5 to 12 have a visible average transmittance of 65% or more, a ^* value of −2 to 2, and b ^* value of −10 to 20 It was a transparent body.

On the other hand, in Comparative Examples 1 to 5, none of the a ^* values satisfy −2 to 2 and the b ^* values satisfy −10 to 20 respectively.

The total Fe amount of the crystalline glass was determined by ICP emission analysis, and the Fe ²⁺ amount was determined by O-phenanthroline spectrophotometry.

The degree of crystallinity is determined by a multiple peak separation method using the X-ray diffractometer (manufactured by Rigaku Corporation) to measure the scattering intensity area of the crystalline glass and the crystal peak area of the crystallized glass measured at a diffraction angle 2θ of 10 to 60 °. And calculated as a ratio (%) of the crystal peak area of the crystallized glass to the scattering intensity area of the crystalline glass.

  The visible transmittance was calculated according to JIS R 3106 from the transmittance at a wavelength of 380 to 780 nm measured using a spectrophotometer for a plate made of crystallized glass that was optically polished on both sides to a thickness of 5 mm.

The a ^* value and b ^* value were calculated from transmittance at a wavelength of 380 to 780 nm measured using a spectrophotometer for a plate made of crystallized glass that was optically polished on both sides to a thickness of 4 mm.

  As described above, since the crystallized glass of the present invention is white opaque or colorless and transparent, front windows such as petroleum stoves and wood stoves, substrates for high-tech products such as color filters and image sensor substrates, and shelf for microwave ovens Suitable for plates, top plates for electromagnetic cooking, window glass for fire doors, etc.

Claims (7)

In terms of mass, TiO ₂ + MgO + ZnO is 1.5 to 4.3%, TiO ₂ / (TiO ₂ + MgO + ZnO) is 0.2 to 0.9, Fe ₂ O ₃ is 50 to 500 ppm, CoO + Cr ₂ O ₃ + NiO + MnO is 5 to 100 ppm, CoO + NiO is contained 0～70Ppm, a ^{Fe 2+} / total Fe is that obtained by heat treatment of 90% or less of crystalline glass _{Li 2 O-Al 2 O 3} -SiO 2 based crystallized glass Li ₂ O—Al ₂ O ₃ —SiO ₂ system having a thickness of 4 mm and an L ^* a ^* b ^* color system having an a ^* value of −2 to 2 and a b ^* value of −10 to ₂₀ Crystallized glass. The Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass according to claim 1, wherein TiO ₂ is 0.3 to 3% in terms of mass%. 3. The Li ₂ O—Al ₂ O ₃ —SiO ₂ -based crystallized glass according to claim 1, wherein an average transmittance of visible light at a wavelength of 380 to 780 nm is 65% or more at a thickness of 5 mm. In mass% _{notation, Li 2 O-Al 2 O} 3 -SiO 2 based crystallized glass according to any one of claims 1 to 3, wherein the content of Sb ₂ O ₃ is 3% or less. By mass% notation, the ZrO ₂ 0.5 to 7%, Li according to any one of claims 1 to 4, characterized in that it contains _{P 2 O 5 0~10% 2 O} -Al 2 O 3 -SiO ₂ based crystallized glass. In mass% _{notation, Li 2 O-Al 2 O} 3 -SiO 2 based crystallized glass according to any one of claims 1 to 5, characterized in that it contains 0-4% of Na ₂ O + K ₂ O. In mass% _{notation, Li 2 O-Al 2 O} 3 -SiO 2 based crystallized glass according to any one of claims 1 to 6, characterized in that it contains Li ₂ O 3.2 to 4.5% .