JP2016121050A - Glass molded body and method for producing glass molded body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass molding comprising colored glass having a curved surface part and a flat part, and including a uniform color tone in which a color difference is not differentiated according to a portion.SOLUTION: In a glass molding 100 including a curved surface part 100a and a flat part 100b, the minimal value of absorbance in a wavelength of 380 nm-780 nm of the flat part 100b is 0.003 or higher, and a color difference ΔE(a numerical value expressed as ΔE={(ΔL)+(Δa)+(Δb)}in a Labcolor system) between the curved surface part 100a and the flat part 100b is 3.2 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a glass molded body having a curved surface portion and a flat portion and a method for producing the glass molded body.

  Cases for electronic devices such as mobile phones and interior panels for automobiles are selected and used from materials such as resin and metal, taking into account various factors such as decoration, scratch resistance, workability, and cost. It has been.

  In recent years, attempts have been made to use glass, which has not been used conventionally, as a casing material (Patent Document 1). According to Patent Document 1, in an electronic device such as a mobile phone, it is said that a unique decoration effect with a sense of transparency can be exhibited by forming the casing body from glass.

JP 2009-61730 A

  Electronic devices such as mobile phones include a display device such as a liquid crystal panel on the outer surface of the device. These display devices tend to have high definition and high brightness, and accordingly, backlights serving as light sources also tend to have high brightness. In addition to irradiating the light from the light source on the display device side, the light may reach the back surface of the housing that is multiple-reflected inside the device and is covered. When metal is used as the material of the housing, there is no problem, but when glass having transparency as described above is used, light from the light source may pass through the housing and be recognized from the outside of the device. Therefore, when glass is used for the housing, a light shielding means such as a coating film for imparting light shielding properties to the glass is formed on the back surface of the housing.

However, as described above, with the increase in the brightness of the light source of the display device, in order to form a coating film having sufficient light shielding properties on the back surface (device side) of the casing, It is necessary to form a film composed of these layers, which increases the number of processes and increases the cost. Moreover, when a coating film is not formed uniformly, there exists a possibility of impairing the beauty | look of apparatuses, such as light permeate | transmitting only the location where a coating film is thin, and a housing | casing being recognized brightly locally. For example, when the housing is processed into a concave shape, it is necessary to form a uniform film on the entire concave surface side, and the process of uniformly forming a coating film having sufficient light-shielding properties is complicated and increases the cost. It becomes a factor.
In addition, when a glass housing is used as a cover member of a display device, the surroundings of the housing are shielded from light such as a coating film for providing light shielding or light reduction, a light reducing means, or a film for coloring. Coloring means such as attaching is formed on the back surface of the housing. Such a display device may be used in a state where a part thereof is bent so as to have a curved surface.

On the other hand, it is possible to eliminate the need for a light-shielding coating film by using a casing made of colored glass.
However, when the colored glass housing has a curved surface portion and a flat portion, a new problem has been found that the light transmittance differs depending on the portion of the housing. This has the same problem in a casing or glass for a cover member of a display device that is used by intentionally blocking or reducing transmitted light.
An object of this invention is to provide the glass forming body which consists of colored glass which has a curved surface part and a flat part and is provided with the uniform color tone from which a color difference does not differ with site | parts. Moreover, the method of manufacturing such a glass molded object with high productivity is provided.

  The present inventors have found that the above object can be achieved by using colored glass having a minimum absorbance of 0.003 or more in the wavelength region of visible light and by making the color difference between the curved surface portion and the flat portion constant or less. .

That is, the glass molded body of the present invention includes a curved surface portion and a flat portion, and the minimum value of absorbance at a wavelength of 380 nm to 780 nm of the flat portion is 0.003 or more, and the curved surface portion and the flat portion The color difference ΔE ^* (in the L ^* a ^* b ^* color system, ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 )) is 3.2. It is characterized by the following.

Moreover, the manufacturing method of the glass forming body of this invention prepares the glass plate whose minimum value of the light absorbency in wavelength 380nm -780nm is 0.003 or more, heats the said glass plate, and then bends using a pressure difference. Depending on the method, the color difference between the curved surface portion and the flat portion ΔE ^* (L ^* a ^* b ^* color system, ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 And a step of forming a curved surface portion and a flat portion whose numerical value is 3.2 or less.

  According to the present invention, it is possible to obtain a glass molded body having a uniform color tone with no difference in color depending on the part. Moreover, such a glass molded object can be manufactured with high productivity.

It is a perspective view of the glass forming body which concerns on embodiment of this invention. It is sectional drawing (sectional drawing which expanded a part) of the glass forming body which concerns on embodiment of this invention.

  Hereinafter, a glass molded body and a method for producing the glass molded body according to the embodiment will be described in detail with reference to the drawings.

[Glass compact]
(First embodiment)
FIG. 1 is a perspective view of a glass molded body 100 according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in the perspective view (AA arrow) in the perspective view of the glass molded body 100, and shows an enlarged part (changed portion from the flat portion to the curved portion). is there.
As shown in FIG. 1, a glass molded body 100 according to the present embodiment includes a glass substrate that is a main body thereof, and the glass substrate is formed flat with a curved surface portion 100 a that is curved on one surface side. The flat portion 100b is also included.

The glass molded body 100 is formed using colored glass so that the minimum absorbance at a wavelength of 380 nm to 780 nm is 0.003 or more so as to absorb a certain amount of light in the visible region and exhibit a desired color tone. If the minimum value of the light absorbency in wavelength 380nm -780nm is 0.003 or more, the glass molded object of a desired color tone can be obtained.
When the minimum value of the absorbance at a wavelength of 380 nm to 780 nm of the glass molded body 100 is less than 0.003, it is possible to obtain a glass molded body 100 having a desired color tone because the glass molded body 100 has a high transmittance in the visible region. May be difficult. The absorbance is preferably 0.02 or more, more preferably 0.3 or more, particularly preferably 0.8 or more, and most preferably 1.0. Further, the maximum absorbance of the glass molded body 100 at a wavelength of 380 nm to 780 nm is preferably 8 or less, more preferably 6 or less, and even more preferably 5 or less.

The method for calculating absorbance in the present invention is as follows. Both surfaces of the glass body are mirror-polished and the thickness t is measured. The spectral transmittance T of this glass body is measured (for example, using a UV-visible near-infrared spectrophotometer V-570 manufactured by JASCO Corporation). Then, the absorbance A is calculated using a relational expression of A = −log ₁₀ T.

  In order to set the minimum value of the absorbance at a wavelength of 380 nm to 780 nm of the glass molded body 100 to 0.003 or more, MpOq (where M is Fe, Se) as a coloring component in the glass constituting the glass molded body 100. , Co, Cu, V, Cr, Pr, Ce, Bi, Eu, Mn, Er, Ni, Nd, W, Rb, Sn, and Ag, and p and q are M and O. It is preferable to use a glass containing 0.001 to 10% in terms of an oxide-based mole percentage. In addition, this content shows those total amounts, when a several coloring component is used. These coloring components are components that give a desired color to the glass, and those having an action of absorbing light having a wavelength in the visible range described above are used. If the coloring component in the glass is less than 0.001%, the transmittance of the visible wavelength region of the glass is high, and it may be difficult to obtain a glass having a desired color tone. Preferably, it is 0.2% or more, typically 1.0% or more, preferably 1.5% or more, and more preferably 2% or more. Moreover, when a coloring component exceeds 10%, there exists a possibility that glass may become unstable. Preferably, it is 6% or less, typically 4% or less, preferably 3% or less.

Further, the coloring components in the glass are expressed in terms of oxide-based mole percentages, 0.01 to 6% for Fe ₂ O ₃ , 0 to 6% for Co ₃ O ₄ , 0 to 6% for NiO, and 0 for MnO. -6%, CuO 0-6%, CuO ₂ 0-6%, Cr ₂ O ₃ 0-6%, V ₂ O ₅ 0-6%, Bi ₂ O ₃ 0-6% It is preferable. Furthermore, Fe ₂ O ₃ may be an essential component, and appropriate components selected from Co ₃ O ₄ , NiO, MnO, Cr ₂ O ₃ , and V ₂ O ₅ may be used in combination. If Fe ₂ O ₃ is less than 0.01%, the desired light-shielding property may not be obtained. Further, when _Fe 2 _{O 3} is 6 percent, the glass is likely to be unstable. Moreover, about other components, there exists a possibility that glass may become unstable that each content exceeds 6%.

In addition, in this specification, content of a coloring component shows the conversion content at the time of assuming that each component which exists in glass exists with the displayed oxide by a mole percentage display. For example, “containing Fe ₂ O ₃ in an amount of 0.01 to 6%” means that the Fe content in the case where all Fe present in the glass exists in the form of Fe ₂ O ₃ , that is, Fe ₂ O of Fe. ₃ equivalent content is 0.01 to 6%. The same applies to other glass components described later.

The glass molded body 100 includes a curved surface portion 100a and a flat portion 100b. The curved surface portion 100a is a portion that is generated when the glass molded body 100 is molded into a desired shape and the surface of the molded body has a curved shape. The flat portion 100b refers to a portion other than the curved surface portion.
The glass molded body 100 of the present embodiment has a color difference ΔE ^* (L ^* a ^* b ^* color system ΔE ^* = {(ΔL ^* ) ² ) so that the curved portion 100a and the flat portion 100b have similar color tones. + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 ) is 3.2 or less. In addition, about the formation method of a curved surface part, it demonstrates in detail by the manufacturing method of the glass forming body mentioned later.

As described above, the glass molded body 100 has a color difference ΔE ^* between the curved surface portion 100a and the flat portion 100b (in the L ^* a ^* b ^* color system, ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + ( Δb ^* ) ² } ^1/2 )) is 3.2 or less. The L ^* a ^* b ^* color system is the CIE 1976 (L ^* a ^* b ^* ) color space (CIELAB) standardized by the International Commission on Illumination (CIE). In the present application, it means the lightness (L ^* ) in the F2 light source and the chromaticity (a ^* , b ^* ) of the reflected light in the F2 light source. ΔE ^* can be obtained by the above-described mathematical formula using the following terms.
ΔL ^* means a difference between L ^* of the curved surface portion defined by the following formula (1) and L ^* of the flat portion ΔL ^* = L ^* (curved surface portion) −L ^* (flat portion) ( 1)
Δa ^* means a difference between a ^* of a curved surface portion defined by the following formula (2) and a ^* of a flat portion Δa ^* = a ^* (curved surface portion) −a ^* (flat portion) 2)
Δb ^* means a difference between b ^* of the curved surface portion defined by the following formula (3) and b ^* of the flat portion Δb ^* = b ^* (curved surface portion) −b ^* (flat portion) (. 3)

Since the color difference ΔE ^* between the curved surface portion 100a and the flat portion 100b is 3.2 or less, the glass molded body 100 has a similar color tone. For this reason, in particular, when a light source is provided on the back side and the light passes through the glass molded body 100, there is no difference in color between the curved surface portion 100a and the flat portion 100b, and a phenomenon occurs in which only a specific part has a different color. Can be suppressed. If the color difference ΔE ^* between the curved surface portion 100a and the flat portion 100b exceeds 3.2, it is not preferable because the curved surface portion 100a and the flat portion 100b are recognized as different colors. The color difference ΔE ^* between the curved surface portion 100a and the flat portion 100b is preferably 2.4 or less, more preferably 1.6 or less, and particularly preferably 0.8 or less.

In the glass molded body 100, the difference Δt (Δt = | ((t2−t1) / t2) × 100 |) between the plate thickness t1 of the curved surface portion 100a and the plate thickness t2 of the flat portion 100b is preferably 5% or less. . Preferably, it is 4% or less, more preferably 3% or less.
By doing in this way, the difference of the plate | board thickness of a curved surface part and a flat part is small, and both color difference (DELTA ⁾ E ^* can be made small. Therefore, the color tone of the curved surface portion and the flat portion can be recognized as substantially the same.
In addition, 0.5-5 mm is preferable and, as for plate | board thickness t1 of a flat part, 1-3 mm is more preferable. The plate thickness t2 of the curved surface portion is preferably 0.5 to 5 mm, and more preferably 1 to 3 mm.
In the glass molded body 100, the plate thickness t <b> 1 of the curved surface portion 100 a refers to the minimum value of the plate thickness in the normal direction on the surface of the curved surface portion 100 a of the glass molded body 100.

The curved surface portion 100a of the glass molded body 100 preferably has a curvature radius of 1 mm to 700 mm. By doing in this way, a glass molded object can be familiarized with a natural form with respect to a member with many curved surface shapes like a vehicle-mounted goods. The curvature radius of the curved surface portion is preferably 300 mm or less, more preferably 100 mm or less, still more preferably 30 mm or less, and particularly preferably 10 mm or less. Further, if the curvature radius of the curved surface portion is less than 1 mm, the difficulty of processing is high. Therefore, the curvature radius of the curved surface portion is preferably 2 mm or more, more preferably 3 mm or more.
In addition, the curvature radius of the curved surface part 100a of the glass molded body 100 means the minimum curvature radius of all the curved surface radii in the surface. The radius of curvature of the curved surface portion 100a of the glass molded body 100 can be measured and calculated using a displacement meter capable of measuring a two-dimensional or three-dimensional shape.

  When the glass molded body 100 is held at a temperature of log η = 5.8 for 1 minute, it is preferable that crystals having a particle size of 50 μm or more do not precipitate inside the glass. By doing in this way, when shape | molding a curved surface part on the surface of the glass molded object 100, it can suppress that a crystal | crystallization precipitates on glass. The cooling rate of the glass molded body 100 in this evaluation refers to the case where the temperature is lowered from the temperature at which log η = 5.8 to room temperature in 10 minutes or less. In addition, since it can remove suitably even if a crystal | crystallization precipitates on the surface of the glass molded object 100, the presence or absence of precipitation of a crystal | crystallization does not ask | require. In addition, in the case of an indeterminate shape or a rod shape, the crystal grain size is regarded as the crystal grain size at the maximum length of the observed shape. In the present specification, η indicates the viscosity of the glass that is the material of the glass molded body, and log η is a value obtained by taking the natural logarithm of the viscosity η.

  The glass molded body 100 of the present invention may be formed of so-called phase-separated glass or crystallized glass in which phase separation or crystals are generated in the glass. By using phase-separated glass or crystallized glass containing a coloring component, a glass molded body having a desired color tone can be obtained. Moreover, the glass molded object made from the chemically strengthened glass provided with high mechanical strength can also be obtained by carrying out the above-mentioned chemical strengthening process of phase-separated glass and crystallized glass. Note that in phase-separated glass and crystallized glass, light is diffused by phase-separation and crystals in the glass. Therefore, when phase-separated glass or crystallized glass is used in the present invention, the total light transmittance of the obtained glass molded body 100 at a wavelength of 380 nm to 780 nm is preferably 30 to 80%.

In crystallized glass, a crystal phase of several nm to several μm in size is distributed in the glass matrix, and by selecting the composition of the base glass and controlling the manufacturing conditions and heat treatment conditions, A glass having a desired color tone can be obtained by changing the size.
In the phase-separated glass, two or more glass phases having different compositions are distributed. There are spinodal in which two phases are continuously distributed and binodal in which one phase is distributed in the form of particles in a matrix, and each phase has a size of 1 μm or less. As the phase separation glass, a glass having a desired color tone can be obtained under the heat treatment conditions for performing composition control for obtaining an appropriate phase separation region and phase separation treatment.

As glass which forms the glass forming body 100, for example, SiO ₂ is 55 to 80%, Al ₂ O ₃ is 0.5 to 16%, and B ₂ O ₃ is 0 to 0 in terms of mole percentage based on the following oxides. 12%, Na ₂ O 5-18%, K ₂ O 0-15%, MgO 0-15%, CaO 0-15%, ΣRO (R is Mg, Ca, Sr, Ba, Zn) Containing 0 to 25%.

SiO ₂ is a component constituting the skeleton of the glass and is essential. If it is less than 55%, the stability as glass will deteriorate, or the weather resistance will deteriorate. Preferably it is 60% or more. More preferably, it is 65% or more. If SiO ₂ exceeds 80%, the viscosity of the glass increases and the meltability decreases significantly. Preferably it is 75% or less, typically 70% or less.

Al ₂ O ₃ is a component that improves the weather resistance and chemical strengthening properties of glass and is essential. If it is less than 0.5%, the weather resistance is lowered. Preferably it is 0.7% or more, typically 1% or more.
If Al ₂ O ₃ exceeds 16%, the viscosity of the glass becomes high and uniform melting becomes difficult. Preferably it is 14% or less, typically 12% or less.
In the case where a high surface compressive stress is formed on the glass surface by the chemical strengthening treatment, Al ₂ O ₃ is preferably 5 to 16% (however, 5% is not included). Further, it enhances the meltability of the glass, when produced at a low cost is, _Al 2 _{O 3} is preferably 0.5 to 5%.

B ₂ O ₃ is a component for improving the weather resistance of glass, but not necessarily can be contained if necessary. When B ₂ O ₃ is contained, if it is less than 4%, a significant effect may not be obtained for improving weather resistance. Preferably it is 5% or more, and typically 6% or more.
If B ₂ O ₃ exceeds 12%, striae due to volatilization may occur and the yield may decrease. Preferably it is 11% or less, typically 10% or less.

Na ₂ O is a component that improves the meltability of glass, and is essential because a surface compressive stress layer is formed by ion exchange. If it is less than 5%, the meltability is poor, and it becomes difficult to form a desired surface compressive stress layer by ion exchange. Preferably it is 6% or more, typically 7% or more.
When Na ₂ O exceeds 18%, the weather resistance decreases. Preferably it is 17% or less, typically 16% or less.

K ₂ O is a component that improves the meltability of the glass and has the effect of increasing the ion exchange rate in chemical strengthening, and is therefore not essential, but is a preferable component. When it contains K ₂ O, if it is less than 0.01%, there is a possibility that a significant effect cannot be obtained for improving the melting property, or a significant effect cannot be obtained for improving the ion exchange rate. Typically, it is 0.3% or more. If K ₂ O exceeds 15%, the weather resistance decreases. Preferably it is 13% or less, typically 10% or less.

  RO (R represents Mg, Ca, Sr, Ba, and Zn) is a component that improves the meltability of the glass, and is not essential, but can contain one or more as required. In that case, if the total RO content ΣRO (ΣRO represents MgO + CaO + SrO + BaO + ZnO) is less than 1%, the meltability may decrease. Preferably it is 3% or more, typically 5% or more. When ΣRO exceeds 25%, the weather resistance decreases. It is preferably 20% or less, more preferably 18% or less, and typically 15% or less.

  MgO is a component that improves the meltability of the glass, and is not essential, but can be contained as necessary. When it contains MgO, if it is less than 3%, there is a possibility that a significant effect cannot be obtained for improving the meltability. Typically 4% or more. When MgO exceeds 15%, the weather resistance decreases. Preferably it is 13% or less, typically 12% or less.

CaO is a component that improves the meltability of the glass, and is not essential, but can be contained as necessary. When CaO is contained, if it is less than 0.01%, a significant effect for improving the meltability cannot be obtained. Typically, it is 0.1% or more. If CaO exceeds 15%, the chemical strengthening properties are lowered. Preferably it is 12% or less, typically 10% or less. Moreover, when making the chemical strengthening characteristic of glass high, it is preferable not to contain substantially.
When high surface compressive stress is formed on the glass surface by the chemical strengthening treatment, CaO is preferably 0 to 5% (however, 5% is not included). Moreover, when raising the meltability of glass and manufacturing cheaply, it is preferable to make CaO into 5 to 15%.

  SrO is a component for improving the meltability, and is not essential, but can be contained as necessary. When it contains SrO, if it is less than 1%, there is a possibility that a significant effect cannot be obtained for improving the meltability. Preferably it is 3% or more, and typically 6% or more. If SrO exceeds 15%, the weather resistance and chemical strengthening properties may be lowered. Preferably it is 12% or less, typically 9% or less.

  BaO is a component for improving the meltability, and is not essential, but can be contained as necessary. When it contains BaO, if it is less than 1%, there is a possibility that a significant effect cannot be obtained with respect to improvement in meltability. Preferably it is 3% or more, and typically 6% or more. If BaO exceeds 15%, the weather resistance and chemical strengthening properties may be reduced. Preferably it is 12% or less, typically 9% or less.

ZrO ₂ is a component that increases the ion exchange rate, and is not essential, but can be contained as necessary. When ZrO ₂ is contained, the range is preferably 5% or less, more preferably 4% or less, and further preferably 3% or less. If the ZrO ₂ content exceeds 5%, the meltability may be deteriorated and remain in the glass as an unmelted product. Typically no ZrO ₂ is contained.

  ZnO is a component for improving the meltability, and is not essential, but can be contained as necessary. When it contains ZnO, if it is less than 1%, there is a possibility that a significant effect cannot be obtained with respect to improvement in meltability. Preferably it is 3% or more, and typically 6% or more. If ZnO exceeds 15%, the weather resistance may be lowered. Preferably it is 12% or less, typically 9% or less.

  In addition to the above components, the following components may be introduced into the glass composition.

SO ₃ is a component that acts as a fining agent, and is not essential, but can be contained as necessary. Fining effect expected in the case of less than 0.005% containing SO ₃ can not be obtained. Preferably it is 0.01% or more, More preferably, it is 0.02% or more. 0.03% or more is most preferable. On the other hand, if it exceeds 0.5%, it becomes a generation source of bubbles, and there is a possibility that the glass melts slowly or the number of bubbles increases. Preferably it is 0.3% or less, More preferably, it is 0.2% or less. 0.1% or less is most preferable.

SnO ₂ is a component that acts as a fining agent, and is not essential, but can be contained as necessary. When SnO ₂ is contained, if it is less than 0.005%, the expected clarification action cannot be obtained. Preferably it is 0.01% or more, More preferably, it is 0.05% or more. On the other hand, if it exceeds 1%, it becomes a generation source of bubbles, and there is a possibility that the glass melts slowly or the number of bubbles increases. Preferably it is 0.8% or less, More preferably, it is 0.5% or less. Most preferred is 0.3% or less.

In addition to the SO ₃ and SnO ₂ described above, chloride or fluoride may be appropriately contained as a fining agent when the glass is melted.

Li ₂ O is a component for improving the meltability, and is not essential, but can be contained as necessary. When Li ₂ O is contained, if it is less than 1%, there is a possibility that a significant effect cannot be obtained for improving the meltability. Preferably it is 3% or more, and typically 6% or more. If Li ₂ O exceeds 15%, the weather resistance may decrease. Preferably it is 10% or less, typically 5% or less.

  The glass molded body 100 may have a surface compressive stress layer on the surface of the molded body. Thereby, a glass molded object with high mechanical strength can be obtained. The depth of the surface compressive stress layer (hereinafter sometimes referred to as DOL) formed on the surface of the glass molded body is preferably reinforced so as to be 5 μm or more, 10 μm or more, 20 μm or more, 30 μm or more. . When a glass molded body is used for an exterior member of an electronic device or the like, the surface of the glass molded body has a high probability of contact damage, and its mechanical strength may be reduced. Therefore, if the DOL is increased, even if the surface of the glass molded body is damaged, it becomes difficult to break. On the other hand, in order to make it easy to cut the glass molded body after the tempering treatment, the DOL is preferably set to 70 μm or less.

  The glass molded body 100 is preferably tempered so that the surface compressive stress (hereinafter sometimes referred to as CS) formed on the glass surface is 300 MPa or more, 500 MPa or more, 700 MPa or more, 900 MPa or more. The mechanical strength of tempered glass becomes high because CS becomes high. On the other hand, if the CS becomes too high, the tensile stress inside the glass may become extremely high. Therefore, the CS is preferably 1400 MPa or less, and more preferably 1300 MPa or less.

The glass molded body 100 may have a design surface on the side formed into the convex shape of the curved surface portion, or may have a design surface on the side formed in the concave shape on the curved surface portion.
In addition, when the glass molded body 100 is used for an exterior member or the like, the design surface means a side facing the outside, that is, a surface visually recognized from the outside as a product. In other words, the opposite side of the side facing the device or the like.

(Other embodiments)
As other embodiment, you may provide both convex shape and concave shape on one side as a curved-surface part. In this specification, the color difference ΔE ^* between the curved surface portion and the flat portion is a measurement object in a portion where the difference between them is the largest. Moreover, when using a glass molding as a housing of an electronic device, the part visually recognized from the outside should be made into a measuring object, and the part hidden by the other member should be excluded from a measuring object.

[Method for producing glass molded body]
Subsequently, the manufacturing method of the glass forming body of this invention is demonstrated.

The method for producing a glass molded body of the present invention comprises a step of preparing a glass plate having a minimum absorbance of 0.003 or more at a wavelength of 380 nm to 780 nm, a method of heating the glass plate, and then bending using a pressure difference. In the color difference ΔE ^* (L ^* a ^* b ^* color system, ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 A curved surface portion and a flat portion having a numerical value) of 3.2 or less.

The step of preparing a glass plate having a minimum absorbance of 0.003 or more at a wavelength of 380 nm to 780 nm is a minimum absorbance of 0.003 or more at a wavelength of 380 nm to 780 nm so as to obtain a glass molded body having a desired color tone. A glass plate is used. If the minimum value of the absorbance at a wavelength of 380 nm to 780 nm is 0.003 or more, a glass molded body having a desired color tone other than colorless and transparent can be obtained.
When the minimum value of the absorbance at a wavelength of 380 nm to 780 nm of the glass plate is less than 0.003, there is a possibility that it is difficult to obtain a glass having a desired color tone because the transmittance of the wavelength in the visible region of the glass molded body is high. The absorbance is preferably 0.02 or more, more preferably 0.3 or more, particularly preferably 0.8 or more, and most preferably 1.0 or more.

Moreover, the glass plate prepared at this process is plate-shaped glass provided with a flat surface. Here, the flat surface does not mean only a flat shape, but also includes a glass plate having a shape with a large curvature radius (for example, a curvature radius exceeding 700 mm).
The method of forming these glass plates is not particularly limited. For example, a suitable amount of various raw materials are prepared, heated to about 1500 to 1600 ° C. and melted, and then homogenized by defoaming, stirring, etc. Then, it is formed into a plate shape by a pressing method or the like, or cast and formed into a block shape. And after slow cooling, it cut | disconnects to desired size, and gives a polishing process as needed, and is manufactured.

In the step of forming the curved surface portion and the flat surface portion, the flat surface portion and the curved surface portion are formed by heating the glass plate prepared in the above-described step of preparing the glass plate and then bending it using a pressure difference (atmospheric pressure-vacuum). And the color difference ΔE ^* (a numerical value represented by ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 in the L ^* a ^* b ^* color system) 3 Both are formed to be 2 or less.
The curved surface portion formed in this step has an arbitrary shape such as a desired shape or pattern. Then, in order to make the color tone of the curved surface portion and the flat portion uniform, in the color difference ΔE ^* (L ^* a ^* b ^* color system, ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } is molded so that the numerical value represented by ^1/2 ) is 3.2 or less. Note that the flat portion does not necessarily mean only flat, but also includes a shape having a large curvature radius (for example, a curvature radius exceeding 700 mm).

In the step of forming the curved surface portion and the flat portion on the glass plate, as described above, the color difference ΔE ^* (L ^* a ^* b ^* color system in the color system ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 ) is 3.2 or less. The L ^* a ^* b ^* color system is standardized by the International Commission on Illumination (CIE). In the present application, it means the lightness (L ^* ) in the F2 light source and the chromaticity (a ^* , b ^* ) of the reflected light in the F2 light source. ΔE ^* can be obtained by the above-described mathematical formula using the following terms.
ΔL ^* means a difference between L ^* of the curved surface portion and L ^* of the flat portion defined by the following equation (4).
ΔL ^* = L ^* (curved surface portion) −L ^* (flat portion) (4)
Δa ^* means a difference between a ^* of the curved surface portion and a ^* of the flat portion defined by the following equation (5).
Δa ^* = a ^* (curved surface portion) −a ^* (flat portion) (5)
Δb ^* means a difference between b ^* of the curved surface portion and b ^* of the flat portion defined by the following equation (6).
Δb ^* = b ^* (curved surface portion) −b ^* (flat portion) (6)

Since the color difference ΔE ^* between the curved surface portion and the flat portion is 3.2 or less, the glass molded body can be recognized as having a substantially uniform color tone. Thereby, for example, in the case of irradiating light from the back side of the glass molded body and recognizing the transmitted light, the color of the glass molded body does not differ depending on the curved surface portion or the flat portion, and the glass molding has a uniform color tone. It can be recognized as a body. Further, for example, when it is desired to shield light from the inside of the electronic device with the glass molded body, light leakage does not occur depending on the part. If the color difference ΔE ^* between the curved surface portion and the flat portion is more than 3.2, the color tone between the curved surface portion and the flat portion can be distinguished and recognized. The color difference ΔE ^* between the curved surface portion and the flat portion is preferably 2.4 or less, more preferably 1.6 or less, and particularly preferably 0.8 or less.

  The step of forming the curved surface portion and the flat portion on the glass plate is performed by a method in which the glass plate is heated and then bent using a pressure difference. The method of bending using a pressure difference is to heat a flat glass plate to above the strain point and below the softening point, bring the mold into contact with one side of the glass plate, and vacuum the space between one side of the glass plate and the mold. A method of deforming the glass plate into a desired shape without pressing with a mold by reducing the pressure by pulling or the like can be mentioned. In this way, in forming a glass plate, a mold contact surface and a non-contact surface are provided simultaneously, and the glass plate is deformed by applying a pressure difference between one surface and the other surface of the glass plate, thereby transferring the mold shape. In this method, a glass molded body having a desired shape is molded. Since the surface in contact with the mold having the shape becomes one glass surface, the other glass surface can be formed without contact, and the glass surface quality such as surface roughness can be kept high. It is said. In addition, a curved surface portion having a small radius of curvature can be formed. Further, even when a curved surface portion having a complicated shape is formed, it can be formed with a single mold.

Moreover, the method of using the following pressure differences may be used for the process of forming a curved surface part and a flat part in a glass plate other than the method of using the above-mentioned pressure difference.
There is also a method of forming a glass molded body having a desired shape by heating a flat glass plate above the strain point and below the softening point and sandwiching it with a set of molds in addition to deformation due to its own weight. is there. By controlling the force sandwiched by the mold to a minimum, the quality of the molded glass surface can be kept high.
There is also a method of forming a glass molded body having a desired shape by heating a rod-shaped or lump-shaped glass material to the softening point or higher and pressing it with a set of rugged molds. By causing the glass material to flow at a temperature equal to or higher than the softening point, a glass molded body having a complicated shape can be formed.
There is also a method of forming a glass molded body having a desired shape by heating a flat glass plate to a strain point or more and less than a softening point, and making contact with a mold by utilizing deformation due to its own weight. . Since only the weight of the glass is used as the driving force without using the pressure difference, the contact pressure with the mold can be kept low, and the surface quality of the contact surface with the mold can be kept high.

Further, in the method for producing a glass molded body of the present invention, after the step of forming the curved surface portion and the flat portion on the glass plate, the surface of the glass molded body on which the curved surface portion and the flat portion are formed is deepened by a strengthening treatment. May be provided with a step of forming a surface compressive stress layer having a surface compressive stress of 300 MPa or more.
By forming the surface compressive stress layer on the surface of the glass molded body, a glass molded body having high strength can be obtained.

  As a method for forming the surface compressive stress layer on the glass surface, an air cooling strengthening method (physical strengthening method) or a chemical strengthening method can be used. The air cooling strengthening method (physical strengthening method) is a method in which the glass plate surface heated to the vicinity of the softening point is rapidly cooled by air cooling or the like. In the chemical strengthening method, alkali metal ions (typically Li ions and Na ions) having a small ion radius existing on the surface of the glass plate by ion exchange at a temperature below the glass transition point are larger than the ion radius. This is a method of exchanging with alkali ions (typically, Na ions or K ions for Li ions and K ions for Na ions).

The chemical strengthening method is not particularly limited as long as it can ion-exchange Na ₂ O on the glass surface layer and K ₂ O in the molten salt. For example, a method of dipping the glass like a heated potassium nitrate (KNO ₃₎ molten salt. The conditions for forming a chemically strengthened layer (surface compressive stress layer) having a desired surface compressive stress on the glass surface differ depending on the thickness of the glass, but the glass is added to the KNO ₃ molten salt at 400 to 550 ° C. It is typical to soak for 2 to 20 hours. Further, as this KNO ₃ molten salt, in addition to KNO ₃ , for example, NaNO ₃ may be contained in an amount of about 5% or less.

  In the step of forming the surface compressive stress layer, the depth of the surface compressive stress layer generated by the glass strengthening process is 5 μm or more. The reason is as follows.

In the production of a glass molded body, the glass surface may be polished, and the particle size of the abrasive grains used for the final stage polishing is typically 2 to 6 μm.
Such abrasive grains are thought to ultimately form microcracks having a maximum size of 5 μm on the glass surface. In order to make the strength improvement effect by the chemical strengthening treatment effective, it is necessary to form a surface compressive stress layer deeper than the microcracks formed on the glass surface. For this reason, the depth of the surface compressive stress layer generated by the chemical strengthening treatment is set to 5 μm or more. Moreover, since the damage | wound exceeding the depth of a surface compressive-stress layer at the time of use will lead to destruction of glass, the one where the surface compressive-stress layer is thick is preferable. For this reason, the surface compressive stress layer is more preferably 8 μm or more, further preferably 10 μm or more, and typically 13 μm or more.

  On the other hand, if the surface compressive stress layer is too deep, the internal tensile stress increases and the impact at the time of fracture increases. In other words, it is known that when the internal tensile stress is large, the glass tends to become a fine piece at the time of breakage and is shattered, increasing the risk. As a result of experiments by the present inventors, it has been found that, in a glass having a thickness of 2 mm or less, when the depth of the surface compressive stress layer exceeds 70 μm, scattering of the glass pieces at the time of breakage becomes significant. Accordingly, in the chemically strengthened glass of the present invention, the depth of the surface compressive stress layer is 70 μm or less. When used as a decorative glass, depending on the application, for example, a portable device having a higher probability of contact scratches on the surface than when applied to an operation panel of a mounting type device such as an AV device / OA device. In the case of application to such applications, it is conceivable to reduce the depth of the surface compressive stress layer for safety. In this case, the depth of the surface compressive stress layer is more preferably 60 μm or less, further preferably 50 μm or less, and typically 40 μm or less.

  Further, in the step of forming the surface compressive stress layer, the surface compressive stress of the surface compressive stress layer generated by the strengthening treatment of the glass molded body is preferably 300 MPa or more, more preferably 500 MPa or more, and 700 MPa or more. More preferably. The surface compressive stress of the surface compressive stress layer is typically 1200 MPa or less.

  Further, the step of forming the curved surface portion and the flat portion may include a step of bending at least two axial directions. By providing such a process, a glass molded body having a complicated shape can be obtained.

  As mentioned above, although an example was given and demonstrated about the glass forming body of this invention, a structure can be suitably changed as needed in the limit which is not contrary to the meaning of this invention.

The glass molded body of this invention can be used suitably for a portable electronic device, for example. The portable electronic device is a concept that includes communication devices and information devices that can be carried around. For example, the communication device includes a mobile phone, a PHS (Personal Handy-phone System), a smartphone, a PDA (Personal Data Assistance), a PND (Portable Navigation Device, a portable car navigation system) as a communication terminal, and a broadcast receiver. Mobile radio, mobile TV, one-seg receiver and the like. Information devices include digital cameras, video cameras, portable music players, sound recorders, portable DVD players, portable game machines, notebook computers, tablet PCs, electronic dictionaries, electronic notebooks, electronic book readers, portable printers, portable scanners, etc. Can be mentioned.
In addition, it can be used as an interior member for automobiles or a design member for home appliances.
Note that the present invention is not limited to these examples.

  EXAMPLES Hereinafter, although it demonstrates in detail based on the Example of this invention, this invention is not limited only to these Examples.

Glass A and glass B used in Examples and Comparative Examples described later will be described.
Commonly used glass materials such as oxides, hydroxides, carbonates, nitrates and the like were appropriately selected so as to have the composition shown in mole percentages in Table 1, and weighed to 100 ml as glass. Note that the SO ₃ described in Table 1, was added to bow the glass raw material nitric _(Na 2 SO _4), a residual SO ₃ remaining in glass after Glauber's salt decomposition, is a calculated value.

  Next, this raw material mixture was put into a platinum crucible and put into a resistance heating type electric furnace at 1500 to 1600 ° C. After the raw material melted off in about 0.5 hours, it was melted for 1 hour and defoamed. Thereafter, the molten raw material was poured into a mold having a length of about 50 mm × width of about 100 mm × height of about 20 mm preheated to about 300 ° C., and slowly cooled at a rate of about 1 ° C./min to obtain a glass block. This glass block was cut and ground to a size of 40 mm × 40 mm (thickness is as shown in Table 1), and finally, both sides were polished to a mirror surface to obtain a plate-like glass having a flat flat surface. Obtained.

  The obtained plate-like glass is shown in Table 1 together with the minimum value of absorbance at a wavelength of 380 nm to 780 nm and the presence or absence of crystal precipitation when held at a temperature of log η = 5.8 for 1 minute.

The minimum value of absorbance at wavelengths of 380 nm to 780 nm was calculated using the spectral transmittance and thickness of the glass as described above. In both glasses A and B, the absorbance at a wavelength of 380 nm was the minimum value.
The presence or absence of crystal precipitation when held at a temperature where log η = 5.8 for 1 minute was confirmed by the following method. Place glass A or glass B cullet on a platinum dish and place in an electric furnace. The temperature inside the electric furnace is raised to a temperature at which each glass has a log η = 5.8, held for 1 minute, and then lowered. The cullet was taken out from the electric furnace, and it was confirmed whether or not crystal precipitation occurred on the glass surface.

Using glass A and glass B, the glass was bent by the following method.
Examples 1 to 3 used a method in which a plate-like glass was heated and then bent using a pressure difference.
Moreover, Example 4 and Example 5 used the method of heating block-shaped glass more than a softening point and pressing with a set of uneven | corrugated shaped metal mold | dies.
Details of the method of bending the plate-like glass of Examples 1 to 3 with a pressure difference are as follows. A glass molded body having a tray shape with the periphery raised as shown in FIG. 1 was prepared. First, a mold having a shape like a tray having a through hole inside is prepared. Next, the plate-shaped glass is placed on the mold so that the space between the plate-shaped glass and the mold is sealed. Then, the following conditions (Example 1: temperature 695 ° C., time: 20 minutes, pressure: 70 kPa, Example 2: temperature 735 ° C., time: 20 minutes, pressure: 70 kPa, Example 3: temperature 735 ° C., time: 10 minutes, While heating the sheet glass and the mold at a pressure of 50 kPa, the space between the sheet glass and the mold was decompressed and held for a predetermined time. By such a molding method, a glass molded body having a flat portion and a curved surface portion described in Table 2 was obtained.
The details of the method of heating the massive glass of Examples 4 and 5 and pressing with a pair of molds having an uneven shape are as follows. In order to create a glass molded body having the convex portions shown in FIGS. 1 and 2, first, a set of molds having an uneven shape is prepared. Next, the massive (cylindrical) glass is heated in a preheating furnace (350 ° C., 5 minutes). Next, heating was performed in a heating furnace (1200 ° C., 10 minutes), the glass temperature was set to the softening point or higher, and then sandwiched and pressed between a pair of molds having an uneven shape. By such a molding method, a glass molded body having a flat portion and a curved surface portion described in Table 2 was obtained.

The plate thickness and chromaticity (L ^* a ^* b ^* color system) were measured for the flat part and the curved part of the obtained glass molded body. Moreover, the curvature radius of the curved surface part described the curvature radius of the metal mold | die used for shaping | molding.
The plate thickness was measured using a micrometer. As for the plate thickness of the curved surface portion, the measurement target was a portion having the smallest curvature radius.
The chromaticity was measured by the reflected light of the F2 light source using a color difference colorimeter (X-LITE, Color i7). In addition, since the chromaticity of a curved surface part cannot be measured, chromaticity was measured using the flat glass of the same composition and board thickness, and it was set as the chromaticity of a curved surface part.

Examples 1, 2 and 4 are the results using glass A, and examples 3 and 5 are the results using glass B. Examples 1 to 3 are examples of the present invention, and examples 4 and 5 are comparative examples.
Table 2 summarizes the detailed results of each example.
In addition, the chromaticity of the curved surface portion is a result of preparing a flat glass having the same thickness (Example 1, Example 2, Example 4 is Glass A, Example 3, Example 5 is Glass B), and measuring the glass. It is.

About the glass molded object of each example, the high-intensity light source was irradiated from the recessed part side of the glass molded object, and it was confirmed visually from the convex part side whether the coloration of the flat part and curved surface part of a glass molded object differed.
As a result, in Example 1, Example 2, and Example 3, ΔE ^* was 3.2 or less, and the difference in color tone between the flat part and the curved part was not felt with the naked eye. On the other hand, in Examples 4 and 5, it was felt that there was a difference in color tone between the flat portion and the curved surface portion.

DESCRIPTION OF SYMBOLS 100 ... Glass molded object, 100a ... Curved surface part, 100b ... Flat part

Claims (10)

A curved surface portion and a flat portion, wherein the flat portion has a minimum absorbance of 0.003 or more at a wavelength of 380 nm to 780 nm, and a color difference ΔE ^* (L ^* a ^* b ^*) between the curved surface portion and the flat portion ^. In the color system, ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 )) is 3.2 or less. body.   The difference Δt (Δt = | ((t2−t1) / t2) × 100 |) between the thickness t1 of the curved surface portion and the thickness t2 of the flat portion is 5% or less. The glass molded body described.   The glass constituting the glass molded body is expressed by mol% based on oxide, and MpOq as a coloring component (where, M is Fe, Se, Co, Cu, V, Cr, Pr, Ce, Bi, 0.001 to 10% of Eu, Mn, Er, Ni, Nd, W, Rb, Sn, and Ag, and p and q are atomic ratios of M and O) The glass molded body according to claim 1 or 2, wherein   The glass molded body according to any one of claims 1 to 3, wherein the curved surface portion has a radius of curvature of 1 mm to 700 mm.   The glass constituting the glass molded body is characterized in that crystals having a particle size of 50 µm or more do not precipitate inside the glass when held at a temperature of log η = 5.8 for 1 minute. The glass molded object of Claim 1. Glass constituting the glass shaped material is represented by mol% based on oxides, the SiO ₂ 55 to 80%, the _{Al 2 O 3 0.5~16%, B} 2 O 3 and 0 to 12%, Na the ₂ O _{5~18%, K 2} O 0 to 15% of MgO 0-15%, 0-15% of CaO, ΣRO (R is Mg, Ca, Sr, Ba, Zn) and 0% to 25% It contains, The glass molded object of any one of Claim 1 thru | or 5 characterized by the above-mentioned.   The said glass molded object has a surface compressive-stress layer whose depth is 5 micrometers or more and whose surface compressive stress is 300 Mpa or more, The glass molded object of any one of Claim 1 thru | or 6 characterized by the above-mentioned. Preparing a glass plate having a minimum absorbance of 0.003 or more at a wavelength of 380 nm to 780 nm;
The method heating the glass plate, then bent using a pressure difference, in the color difference ^{ΔE * (L * a * b} * color system of the curved surface portion and the flat ^{portion, ΔE * = {(ΔL *} ) 2 + ( And a step of forming a curved surface portion and a flat portion having a value of Δa ^* ) ² + (Δb ^* ) ² } ^1/2 ) of 3.2 or less. .   9. The method according to claim 8, further comprising a step of forming a surface compressive stress layer having a depth of 5 μm or more and a surface compressive stress of 300 MPa or more by strengthening the glass molded body on which the curved surface portion and the flat portion are formed. The manufacturing method of the glass molded object of description.   The method for producing a glass molded body according to claim 8 or 9, wherein the step of forming the curved surface portion and the flat portion includes a step of bending in at least two axial directions.

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