JP6955190B2 - Glass member and its manufacturing method - Google Patents

Description

The present invention relates to a glass member and a method for producing the same.

In recent years, there has been a demand for weight reduction of glass members used for windows of mobile phones, automobiles, automobile displays, and the like. In response to such a demand, thinning of glass has generally been proposed (see, for example, Patent Document 1).

Patent No. 5633718

However, since general glass has a high density, there is a limit to reducing the weight of the glass member.

In view of the above, it is an object of the present invention to provide a lightweight glass member.

The glass member of the present invention is characterized in that the inside is a porous phase and the surface layer portion is a dense phase. In this way, the weight of the glass member can be reduced.

The glass member of the present invention preferably has a surface roughness Ra of 100 nm or less. In this way, the light scattering on the surface tends to be small, and the light transmittance in the visible light region of the glass member tends to be high.

The glass member of the present invention preferably has a pore diameter of 100 nm or less in the porous phase. In this way, since the pore diameter of the hole is sufficiently smaller than the visible light wavelength, the light transmittance of the glass member in the visible light region tends to be high.

In the glass member of the present invention, the thickness of the dense phase is preferably 0.1 to 100 μm.

It is preferable that the glass member of the present invention contains gas in the pores of the porous phase, or the inside of the pores of the porous phase is in a reduced pressure state. In this way, further weight reduction is possible. The term "gas" as used herein means a gas that becomes a gas at room temperature, and the term "decompression" indicates a pressure lower than atmospheric pressure.

The glass member of the present invention preferably has a density of less than ^{2.2 g / cm 3.}

The glass member of the present invention preferably has a haze rate of 10% or less in the visible light region.

The method for producing a glass member of the present invention includes a step of heat-treating a glass base material to split it into two phases, a step of removing one phase with an acid or an alkali to obtain a porous body, and a surface of the porous body. It is characterized by including a step of forming a dense phase by heat treatment. According to this method, a glass member can be easily manufactured.

The method for producing a glass member of the present invention includes a step of heat-treating a glass base material to divide it into two phases, a step of obtaining a porous body by removing one phase with an acid or an alkali, and a step of obtaining the porous body. It is characterized by including a step of forming a dense phase by laminating a glass plate on the surface of the above. According to this method, a glass member can be easily manufactured.

According to the present invention, it is possible to provide a lightweight glass member.

It is a schematic cross-sectional view which shows an example of the glass member of this invention. It is a schematic cross-sectional view which shows the other example of the glass member of this invention. It is a schematic cross-sectional view which shows 1st Embodiment of the manufacturing method of the glass member of this invention. It is a schematic cross-sectional view which shows the 2nd Embodiment of the manufacturing method of the glass member of this invention.

Hereinafter, embodiments of the glass member of the present invention will be described. However, the present invention is not limited to the following embodiments.

FIG. 1 is a schematic cross-sectional view showing an example of the glass member of the present invention.

The glass member 1 of the present invention is characterized in that the inside is a porous phase 2 and the surface layer portion is a dense phase 3. Since the inside is composed of the porous phase 2, the weight of the glass member 1 can be reduced. Further, since the surface layer portion is composed of the dense phase 3, gas, moisture and the like are less likely to enter the holes 4, and deterioration and mass change of the glass member 1 can be prevented. The "dense phase" means a phase in which pores having a pore diameter of 1 nm or more are not formed.

The shape of the glass member 1 is not particularly limited, but is usually plate-shaped. In addition, it can have a general glass shape such as a rod shape, a tubular shape, a lens shape, a fiber shape, and a block shape.

The surface roughness Ra of the glass member 1 is preferably 100 nm or less, 90 nm or less, and particularly preferably 80 nm or less. If Ra is too large, light scattering on the surface tends to be large, so that the light transmittance of the glass member 1 in the visible region tends to decrease. The lower limit of Ra is not particularly limited, but is practically 0.05 nm or more.

The pore diameter of the pore 4 in the porous phase 2 is preferably 100 nm or less, 90 nm or less, and particularly preferably 80 nm or less. If the hole diameter of the hole 4 is too large, light tends to be scattered and the light transmittance of the glass member 1 in the visible light region tends to be low. The lower limit of the hole diameter of the hole 4 is not particularly limited, but is actually 10 nm or more.

The pores 4 of the porous phase 2 preferably contain a gas. The gas is preferably air, a rare gas such as nitrogen, oxygen, hydrogen or argon, a mixed gas or the like. By containing gas in the holes 4, the weight of the glass member 1 can be easily reduced. In order to make the glass member 1 lighter, it is particularly preferable that the gas is hydrogen or nitrogen, which is lighter than air. Further, the hole 4 may be in a reduced pressure state.

The thickness of the dense phase 3 is preferably 0.1 to 100 μm, 0.5 to 90 μm, and particularly preferably 1 to 80 μm. If the thickness of the dense phase 3 is too small, the glass member 1 is liable to break. On the other hand, if the thickness of the dense phase 3 is too large, it becomes difficult to reduce the weight of the glass member 1.

The density of the glass member 1 having the above configuration tends to be ^{less than 2.2 g / cm 3} , 2.1 g / cm ³ or less, and particularly 2 g / cm ^{3 or less.} By the way, it is generally known that there is a positive correlation between density and permittivity. Since the dielectric constant decreases as the density decreases, the glass member of the present invention can also be used as a substrate material for which a low dielectric constant is required for mobile phones, tablet PCs, and the like.

Further, the haze rate tends to be 10% or less, 9% or less, and particularly 8% or less in the visible light region. If the haze rate is too large, the transparency of the glass member 1 is impaired, making it difficult to use for a display such as a mobile phone. The lower limit of the haze rate is not particularly limited, but in reality, it is 0.1% or more.

The hole 4 has various shapes such as a true sphere, a substantially ellipsoid, and a tubular shape.

FIG. 2 is a schematic cross-sectional view showing another example of the glass member of the present invention. In FIG. 2, the hole 4 is a through hole connected from the surface to the inside.

Next, the method for manufacturing the glass member of the present invention will be described.

(First Embodiment)
FIG. 3 is a schematic cross-sectional view showing a first embodiment of the method for manufacturing a glass member of the present invention.

First, a glass raw material is prepared so as to have a glass composition as described below.

As the glass composition, as will be described later, it is preferable that the borosilicate glass is easily phase-separated by heat treatment.

As borosilicate glass, SiO ₂ 50 to 80%, B ₂ O _{3 to} 40%, R ₂ O (R is at least one selected from Li, Na, and K) 0 to 20 in mass%. %, R'O (R 'is Mg, Ca, at least one selected from Sr and _{Ba) 0~20%, Al 2 O} 3 0~10%, P 2 O 5 0~10%, ZnO 0~ It preferably contains 10%. The reason why the content of each component is specified as described above will be described below. Unless otherwise specified, "%" means "mass%" in the following description of the component content.

SiO ₂ is a component that forms a glass network. The content of SiO ₂ is preferably 50 to 80%, particularly preferably 50 to 75%. If _{the content of SiO 2} is too small, the weather resistance and mechanical strength tend to decrease. On the other hand, _{if the content of SiO 2} is too large, the melting temperature tends to be high.

B ₂ O ₃ is a component that forms a glass network and promotes phase separation. The content of B ₂ O ₃ is preferably 1 to 40%, 2 to 38%, and 2 to 35%. If _{the content of B 2} O ₃ is too small, it is difficult to obtain the above effect. On the other hand, _{if the content of B 2} O ₃ is too large, the weather resistance tends to decrease.

R ₂ O (R is at least one selected from Li, Na and K) is a component that lowers the melting temperature to improve meltability and promotes phase separation. The content of R ₂ O 0 to 20%, particularly preferably from 0.1 to 18%. When the content of R 2 _O is too large, the weather resistance tends to decrease. The contents of Li ₂ O, Na ₂ O and K ₂ O are preferably 0 to 20%, particularly preferably 0.1 to 18%, respectively.

R'O (R'is at least one selected from Mg, Ca, Sr and Ba) is a component that lowers the melting temperature and improves the meltability. The content of R'O is preferably 0 to 20%, particularly preferably 0.1 to 18%. If the R'O content is too high, the weather resistance tends to decrease. The contents of MgO, CaO, SrO and BaO are each preferably 0 to 20%, particularly preferably 0.1 to 18%.

Al ₂ O ₃ is a component that improves weather resistance and mechanical strength. The content of Al ₂ O ₃ is preferably 0 to 10% and 0 to 8%. If _{the content of Al 2} O ₃ is too large, the meltability tends to decrease.

P ₂ O ₅ is a component that lowers the melting temperature and promotes phase separation. The content of P ₂ O ₅ is preferably 0 to 10%, particularly preferably 0.1 to 8%. If the ZnO content is too high, the weather resistance tends to decrease.

ZnO is a component that lowers the melting temperature and improves the meltability. The ZnO content is preferably 0 to 10%, particularly preferably 0.1 to 8%. If the ZnO content is too high, the weather resistance tends to decrease.

In addition to the above components, various components can be contained as long as the effects of the present invention are not impaired. For example, TiO ₂ , ZrO ₂ , La ₂ O ₃ , Ta ₂ O ₅ , TeO ₂ , Nb ₂ O ₅ , Gd ₂ O ₃ , Y ₂ O ₃ , Eu ₂ O ₃ , Sb ₂ O ₃ , SnO ₂ , P. ₂ O ₅ , Bi ₂ O _3, ZnO and the like may be contained in a range of 15% or less, further 10% or less, particularly 5% or less, and a total amount of 30% or less.

Next, the prepared glass batch is placed in a platinum crucible and then melted at 1400 to 1600 ° C. for 2 to 48 hours. Next, the molten glass is poured onto a carbon plate, formed into a plate shape, and then slowly cooled at 300 to 600 ° C. for 10 minutes to 10 hours to obtain a glass base material 5. In addition, in order to make the obtained glass base material 5 into a desired shape, processing such as cutting and polishing may be performed.

The obtained glass base material 5 is heat-treated and split into two phases (glass phase 6 and glass phase 7). The heat treatment temperature is preferably 400 to 800 ° C. and 450 to 750 ° C., particularly preferably 500 to 700 ° C. If the heat treatment temperature is too high, the glass base material 5 softens and it becomes difficult to obtain a desired shape. On the other hand, if the heat treatment temperature is too low, it becomes difficult to separate the phases of the glass base material 5. The heat treatment time is preferably 10 minutes or more, 1 hour or more, and particularly preferably 3 hours or more. If the heat treatment time is too short, it becomes difficult to separate the phases of the glass base material 5. The upper limit of the heat treatment time is not particularly limited, but in reality, it is 180 hours or less.

Next, the glass base material 5 split into two phases is immersed in an acid or an alkali to remove the glass phase 7 to obtain a porous body 8 having pores. As the acid, hydrochloric acid, sulfuric acid, nitric acid and hydrofluoric acid can be used. In addition, these acids may be mixed and used. As the alkali, an aqueous solution of sodium hydroxide or potassium hydroxide can be used. In addition, these alkalis may be mixed and used. The immersion time of the acid or alkaline aqueous solution is preferably 1 hour or longer, 10 hours or longer, and particularly preferably 20 hours or longer. If the immersion time is too short, it becomes difficult to obtain the porous body 8. The upper limit of the immersion time is not particularly limited, but in reality, it is 100 hours or less. The immersion temperature is preferably 20 ° C. or higher, 25 ° C. or higher, and particularly preferably 30 ° C. or higher. If the immersion temperature is too low, it becomes difficult to obtain the porous body 8. The upper limit of the immersion temperature is not particularly limited, but in reality, it is 95 ° C. or lower.

Next, the pores on the surface of the porous body 8 are sealed by heat-treating the porous body 8 to form a dense phase. In this way, a glass member 1 having a porous phase 2 inside and a dense phase 3 on the surface layer is obtained. Examples of the heat treatment method include heat treatment using a gas burner and an electric furnace. By heat-treating the surface of the porous body 8 with a gas burner or an electric furnace and softening, deforming, and densifying only the surface of the porous body 8, the holes on the surface of the porous body 8 can be sealed. The heat treatment temperature in the electric furnace is preferably 400 to 800 ° C. and 450 to 750 ° C., particularly preferably 500 to 700 ° C. If the heat treatment temperature is too high, not only the surface of the porous body 8 but also the inside is likely to be softened and deformed. On the other hand, if the heat treatment temperature is too low, the surface of the porous body 8 is less likely to be softened and deformed, and the pores on the surface are less likely to be sealed. The heat treatment time is preferably 5 minutes to 10 hours, 10 minutes to 8 hours, and particularly preferably 20 minutes to 6 hours. If the heat treatment time is too long, not only the surface of the porous body 8 but also the inside is easily softened and deformed. On the other hand, if the heat treatment time is too short, the surface of the porous body 8 is less likely to be softened and deformed, and the pores on the surface are less likely to be sealed.

The resulting composition of the glass member 1, by _{mass%, SiO 2 60~99.5%, B} 2 O 3 0~5%, Al 2 O 3 0~5%, R 2 O (R is Li, Na , At least one selected from K) 0-5%, R'O (R'is at least one selected from Mg, Ca, Sr and Ba) 0-5%.

(Second Embodiment)
FIG. 4 is a schematic cross-sectional view showing a second embodiment of the method for manufacturing a glass member of the present invention.

The procedure is the same as that of the first embodiment except for the step of sealing the pores on the surface of the porous body 8.

In the second embodiment, a glass plate 9 is attached to the surface of the porous body 8 to form a dense phase, and the holes on the surface are sealed to obtain the glass member 1.

As a method of bonding the porous body 8 and the glass plate 9, a method of fusing the porous body 8 and the glass plate 9 by heat treatment, bonding with glass frit or resin, atomic diffusion bonding, surface activation bonding, anode bonding, etc. Can be used.

The thickness of the glass plate 9 is preferably 1 to 100 μm, 5 to 90 μm, and particularly preferably 10 to 80 μm. If the thickness of the glass plate 9 is too small, it may be damaged during bonding. If the thickness of the glass plate 9 is too large, it becomes difficult to obtain lightweight glass.

The difference in the coefficient of thermal expansion (30 to 300 ° C.) between the porous body 8 and the glass plate 9 is preferably 10 ppm / ° C. or lower, 8 ppm / ° C. or lower, and particularly preferably 5 ppm / ° C. or lower. If the difference in the coefficient of thermal expansion is too large, stress is applied to the porous body 8 and the glass plate 9, and damage such as peeling is likely to occur.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited to these examples.

(Example 1)
First, in _{mass%, SiO 2 63%, Al} 2 O 3 3%, B 2 O 3 27%, such that the _Na 2 O 7% of the glass composition, placed in a glass batch was prepared glass raw materials in a platinum crucible After that, it was melted at 1550 ° C. for 24 hours. When the glass batch was melted, it was stirred using a platinum stirrer to homogenize it. Next, the molten glass was poured onto a carbon plate, formed into a plate shape, and then slowly cooled at 500 ° C. for 30 minutes. The obtained sample was cut and polished to obtain a glass base material having a size of 20 × 20 mm × 0.5 mm (thickness).

The obtained glass base material was heat-treated at 540 ° C. for 72 hours in an electric furnace to separate the phases. The glass base material after phase separation was immersed in 1N sulfuric acid (90 ° C.) for 50 hours and then washed with pure water to obtain a porous body.

The surface of the obtained porous body was heat-treated with a gas burner to seal the holes on the surface to obtain a glass member.

When the cross section of the obtained glass member was observed with an optical microscope, the inside of the glass member was porous and the surface layer portion was dense. In addition, the composition, haze rate, peak of narrow mouth distribution inside, surface roughness Ra, and density of the obtained glass member were measured. The composition of the glass member, _SiO 2 _96% by _{mass%, B 2 O 3 3%} , was _Na 2 O 1%. The haze ratio was 2.5%, the peak of the internal pore distribution was 4 nm, the surface roughness Ra was 12 nm, and the density was 2.0 g / cm ³ .

(Example 2)
An ultrathin glass (G-Leaf manufactured by Nippon Electric Glass Co., Ltd.) having a thickness of 30 μm is heat-treated in an electric furnace at 750 ° C. for 3 hours and bonded to the entire surface of the porous body produced in Example 1 to form a glass member. Obtained.

When the cross section of the obtained glass member was observed with an optical microscope, the inside of the glass member was porous and the surface layer portion was dense. In addition, the haze rate of the obtained glass member, the peak of the small diameter distribution inside, the surface roughness Ra, and the density were measured. The haze ratio was 2.5%, the peak of the internal pore size distribution was 4 nm, the surface roughness Ra was 9 nm, and the density was 2.1 g / cm ³ .

The composition was measured with an energy dispersive X-ray analyzer (EX-250 manufactured by HORIBA, Ltd.).

The haze rate was measured based on JIS K7361-1-1997 using an ultraviolet-visible near-infrared analysis photometer (UV-3100PC manufactured by Shimadzu Corporation).

The peak of the internal pore distribution was measured by a pore distribution measuring device (QUADRASORB evo manufactured by Kantachrome).

The surface roughness Ra was measured by a surface roughness measuring instrument (SE700 manufactured by Kosaka Research Institute).

Density was measured by the Archimedes method.

The glass member of the present invention is suitable as a lightweight window for a moving body such as an automobile, a lightweight display device such as a television, and a low dielectric constant base material for an electronic wiring board.

1 Glass member 2 Porous phase 3 Dense phase 4 Holes 5 Glass base material 6 Glass phase 7 Glass phase 8 Porous body 9 Glass plate

Claims (8)

A glass member characterized in that the inside is a porous phase, the surface layer portion is a dense phase, and the surface roughness Ra is 100 nm or less. A glass member characterized in that the inside is a porous phase, the surface layer portion is a dense phase, and the haze rate is 10% or less in the visible light region. Glass member according to claim 1 or 2 pore size of pores in the porous phase is characterized in that at 100nm or less. The glass member according to any one of claims 1 to 3, wherein the thickness of the dense phase is 0.1 to 100 μm. The glass member according to any one of claims 1 to 4, wherein the pores of the porous phase contain gas, or the inside of the pores of the porous phase is in a reduced pressure state. The glass member according to any one of claims 1 to 5, wherein the density is less than 2.2 g / cm ^3. A method for manufacturing the glass member according to any one of claims 1 to 6.
A step of heat-treating the glass base material to split it into two phases, a step of obtaining a porous body by removing one phase with an acid or an alkali, and a step of heat-treating the surface of the porous body to form a dense phase. A method for manufacturing a glass member, which comprises a process. A step of heat-treating the glass base material to split it into two phases, a step of obtaining a porous body by removing one phase with an acid or an alkali, and a step of laminating a glass plate on the surface of the porous body. A method for manufacturing a glass member, which comprises a step of forming a dense phase.

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