JPH08277142A - Composition for opal glass - Google Patents

Abstract

PURPOSE: To obtain a composition for an opal glass without containing the significant amount of fluorine compound, safe and easy to produce, without having fear for air pollution, effects on human health and agricultural products, high in opacity, and capable of conducting a low temperature melting. CONSTITUTION: The composition for an opal glass is constituted by containing 35-65wt.% SiO2 , 3.5-10wt.% P2 O5 , 5.5-15wt.% Al2 O3 and 3-15wt.% CaO.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a milk-white glass composition, and more particularly, to a milk-white glass composition which does not contain a significant amount of fluorine, is safe and easy to produce, has a high milkiness, and can be melted at a low temperature. Regarding

[0002]

2. Description of the Related Art Light transmission is achieved by interposing particles having different refractive indexes in transparent glass to cause light scattering or by uniformly dispersing a certain amount of opaque fine particles from the beginning. Glass that has been made milk white by reducing the rate is generally called milk white glass, and from the viewpoint of good aesthetics and storage stability, it can be used for containers, tableware, building materials, etc.
Widely used.

Here, as a composition for milky white glass, generally, a fluoride type, a borosilicate type and a phosphate type are known.

A fluoride-based composition for milk-white glass is described in, for example, JP-A-62-52140, which contains 70 to 73% by weight of SiO ₂ and 4 to 6% by weight of fluorine. The main crystalline phase is NaF.

However, when glass is mass-produced from a fluoride-based composition on an industrial production scale, as a raw material,
Fluorite (CaF ₂ ), sodium fluorosilicate (Na ₂ Si
F ₆ ), cryolite (Na ₃ AlF ₆ ), etc. are used,
Fluorine gas was volatilized to the atmosphere by about 10 to 50% when the glass was melted, which was extremely harmful to air pollution, human health, and agricultural products, and there was a problem of lack of safety.

Fluoride-based compositions are also used for NaF and Ca.
The F ₂ crystal growth and precipitation rates are very fast, and even if the glass is rapidly cooled from the molten state, there is an advantage that it can be opalescent, but on the contrary, the crystal growth and precipitation rates are too fast to control. However, there is a problem that the grown crystal is too large, the strain is generated due to the difference in the coefficient of thermal expansion between the crystal layer and the glass phase, and the glass is easily broken.

Further, when cooled, NaF is removed from the viscous glass.
When a large amount of CaF ₂ or CaF ₂ is deposited, in the glass phase, SiO
₂ becomes rich. Therefore, SiO ₂ is devitrified, opacity may change, become SiO ₂ itself tends to precipitate, the mechanical strength of the glass was also observed problems such as lowered. That is, when SiO ₂ is deposited, a crack is generated around the deposited SiO ₂ crystal due to the difference in coefficient of thermal expansion from the glass phase surrounding the crystal, and thus a glass product has a fatal defect. Becomes

On the other hand, the composition of borosilicate is disclosed in JP-A-50-5.
5611, JP 61-247642, JP 63-2.
As shown in Japanese Patent No. 65841, a glass component generally has a high content of SiO ₂ or B ₂ O ₃ , and further contains a small amount of P ₂ O ₅ or CaO, and is phase-separated in a certain composition range. To create milky glass.

However, in the composition of borosilicate, Al
_In general, the amount of ₂ O ₃ added was small, the degree of opalescence was insufficient, and the unevenness of opalescence was large.

This is because, as described in JP-A-50-55611, when the added amount of Al ₂ O ₃ exceeds 5% by weight, the color development of glass is significantly inhibited, that is, the opacification degree is decreased. This is because it becomes insufficient, and further, JP-A-61-61
As described in JP-A-247642, Al ₂
If the added amount of O ₃ exceeds 2.7 wt%, 1380 ° C.
This is also because the melting operation below becomes difficult and the viscosity becomes high, which makes the molding operation difficult.

Further, the composition of borosilicate is disclosed in JP-A-50-5.
As described in Japanese Patent Publication No. 5611, etc., it is difficult to reduce the amount of SiO ₂ added, because the water resistance generally decreases, and as a result, the melting temperature of glass is 14
There is a problem that the temperature becomes as high as 50 to 1580 ° C., a large amount of energy is required at the time of glass production, and the cost becomes high. That is, when the melting temperature of the glass is high, there is a problem that the refractory brick used in the glass melting furnace is easily eroded by the glass and the life of the glass melting furnace is shortened. Therefore, as disclosed in Japanese Patent Laid-Open No. 63-265841, it was thought that P ₂ O ₅ could only be added at about 2.5% and CaO at about 1.5%.

Further, as a milky white glass, a phosphoric acid composition in which the content of B ₂ O ₃ is decreased and the content of P ₂ O ₅ is increased is proposed in, for example, Japanese Patent Application Laid-Open No. 50-51513. Has been done. However, such a composition is
₂ O ₃ and B ₂ O ₃ are added in a small amount, which is an index for obtaining a milky white color. The light transmittance in a wavelength range of 340 to 700 nm is as high as 4 to 13%, which causes a problem of low milkiness. there were. In addition, there was a problem that the chemical stability was poor and the coefficient of thermal expansion was high.

[0013]

That is, the present invention is
It is intended to provide a composition for a milky white glass which does not contain a significant amount of a fluorine compound, is safe and easy to produce, has no concern about air pollution, human health, agricultural products, and has a high opacification degree and can be melted at a low temperature. To aim.

[0014]

SUMMARY OF THE INVENTION The present invention uses SiO _2
5 to 65% by weight, P ₂ O ₅ to 3.5 to 10% by weight, Al
_The composition of the composition for milky-white glass is characterized by containing 5.5 to 15% by weight of ₂ O ₃ and 3.0 to 15% by weight of CaO, and such a configuration can solve the conventional problems. The present invention will be described below by dividing it into constituent elements.

(SiO ₂ ) SiO ₂ is a basic component forming a glass network structure in the present invention. That is, it has an amorphous structure and exhibits excellent mechanical strength, weather resistance, or luster as glass.

The content of such SiO ₂ is 35-35.
A range of 65% by weight is essential. Below 35% by weight,
There is a possibility that the weather resistance and moisture resistance of the glass may be lowered, while on the other hand, when it exceeds 65% by weight, the melting temperature of the glass becomes high, specifically, the melting temperature of 1400 ° C. or higher is required. This is because the purpose of the present invention to provide a milky-white glass that can be melted at a low temperature is not achieved.

From the viewpoint of a good balance between the weather resistance and the melting temperature of glass, the content of SiO ₂ is more preferably in the range of 40 to 60 (excluding 60% by weight)% by weight. Yes, optimally 45-55 (5
It does not include 5% by weight).

Generally, from the viewpoint of deterioration of weather resistance and water resistance of glass, the content of SiO ₂ is, as shown in the above-mentioned prior art examples, at least 60 to 65% by weight. % Or more, it is said that in the present invention, by combining with other constituent components, S without deteriorating the weather resistance and water resistance of the glass.
It has the significance of lowering the content of iO ₂ and remarkably expanding the usable range of SiO ₂ .

(P ₂ O ₅ ) P ₂ O ₅ is a basic component that phase-separates with the SiO ₂ component and remarkably promotes opalescence of glass. However, with only P ₂ O ₅ and SiO ₂ components, no matter how much the content of P ₂ O ₅ is increased, the increase in opalescence is insufficient. That, P ₂ O ₅ is I cooperation with the other components of the present invention, and Bunsho effective as the first SiO ₂ component, uniformly form a predetermined size refractive index different phases of milky degree It is possible to obtain high-quality glass.

In the present invention, the content of P ₂ O ₅ is
The range of 3.5 to 10% by weight is essential. When the content of P ₂ O ₅ is less than 3.5% by weight, the opacification degree of the glass is insufficient. On the other hand, when the content of P ₂ O ₅ exceeds the range of 10% by weight, conversely, milky white unevenness occurs. Is increased, and the aesthetics of the glass may be impaired.

From the viewpoint of a better balance between the milky whiteness and the appearance, 4 to 10% by weight is more preferable, and the optimum range is 4.5 to 8% by weight.

As mentioned above, Japanese Patent Laid-Open No. 63-265
As disclosed in Japanese Patent Publication No. 841), refractory bricks used in a glass melting furnace using glass are easily eroded,
Since the life of the glass melting furnace is shortened, P ₂ O ₅ is added to 2.
It was generally believed that only about 5% could be added, but in the composition combination of the present invention, P ₂ O ₅
Even if it exceeds 2.5%, no such problem has been observed.

(Al ₂ O ₃ ) In the present invention, Al ₂ O
It is essential that ₃ to be contained in an amount of 5.5 to 15% by weight. That is, Al ₂ O ₃ functions to reduce the chemical durability and the coefficient of thermal expansion of glass, and also significantly improves the dispersion stability of SiO ₂ and other components to make the phase separation of the glass uniform and easy. It has the function of closing. That is,
The opalescence of the opalescent glass of the present invention is uniformly and easily promoted.

Here, the total amount of Al ₂ O ₃ is 5.5 to 1
If the content is less than 5.5% by weight, the effect of improving the dispersion stability of SiO ₂ and other components may be poor, while the content of 15% by weight is defined as 5% by weight. If it exceeds, the melting temperature of the glass may be remarkably increased, or conversely, the opalescence may be decreased.

Further, in order to improve the balance between dispersion stability and glass melting temperature and the like, the content of Al ₂ O ₃ is preferably 5.7 to 10% by weight, and optimally, It is in the range of 6 to 9% by weight.

In the present invention, even if the added amount of Al ₂ O ₃ exceeds 5% by weight, the color development of glass as described in JP-A-50-55611 is significantly inhibited. As described in Japanese Patent Laid-Open No. 61-247642, problems such as difficulty in molding at 1380 ° C. or high viscosity and difficulty in molding work have been observed. Absent.

(CaO) In the present invention, it is essential to contain CaO in an amount of 3 to 15% by weight based on the total amount. That is,
CaO has a function of reducing the viscosity of glass at high temperatures and a function of improving the opacification degree.

Here, the content of CaO is 3 to 1 of the total amount.
The content of 5% by weight is specified because if the content is less than 3% by weight, the opacification degree may decrease, and conversely if the content exceeds 15% by weight, the melting temperature of glass becomes high. This is because the thermal expansion coefficient may increase.

In addition, the content of CaO is preferably 5 to 14% by weight, and optimally 6 to 13 in order to improve the balance between opalescence and glass melting temperature.
It is in the range of% by weight.

As described above, in the present invention, as disclosed in Japanese Patent Laid-Open No. 63-265841, the refractory bricks used in the glass melting furnace using glass are easily eroded, and Since the life is shortened, C
It was generally thought that only about 1.5% of aO could be added, but in the combination of the composition of the present invention, even if CaO exceeds 1.5%, the melting point of glass is low. No particular problems have been seen. However, in a glass melting furnace using inappropriate refractory bricks, the composition of the present invention may corrode, so caution is required.

(Other glass components) In the present invention, it is preferable to include the following components in addition to the above composition components.

(Na ₂ O) The total amount of Na ₂ O was 4 to 1
It is preferable to contain 5% by weight. That is, addition of Na ₂ O is suitable in that the melting property of glass is lowered.

Here, it is preferable that the range of the content of Na ₂ O is 4 to 15% by weight of the total amount, which is 4% by weight.
If the amount is less than the above, the effect of addition is poor, and conversely, if it exceeds 15% by weight, the weather resistance of the glass may be lowered, or the coefficient of thermal expansion may be increased. In addition, the balance between the effect of such addition and the weather resistance of the glass is more favorable, and therefore 5
The optimum range is from 10 to 10% by weight.

(K ₂ O) K ₂ O is preferably contained in an amount of 1 to 10% by weight based on the total amount. That is, the addition of K ₂ O increases the opacification degree of the glass, makes the temperature gradient during melting of the glass gentle, widens the working temperature range, and due to the so-called mixed alkali effect, N in the glass is added.
It is preferable in that it suppresses the movement of a ions.

Here, the range of the content of K ₂ O is preferably 1 to 10% by weight of the total amount. If it is less than 1% by weight, the effect of addition is poor, and conversely 10% by weight. This is because if it exceeds%, the melting temperature of the glass may increase. In addition, the range of 2 to 5% by weight is optimum in terms of a better balance between the effect of addition and the weather resistance of glass.

(ZnO) ZnO is preferably contained in an amount of 2 to 10% by weight based on the total amount. ZnO is suitable because it exhibits a flux effect by adding a small amount, increases the meltability of the glass, improves the opacification degree of the glass, lowers the coefficient of thermal expansion, and further improves the weather resistance.

Here, the range of the content of ZnO is preferably 1 to 10% by weight of the total amount. If it is less than 1% by weight, the effect of addition is poor, and conversely, 10% by weight. If it exceeds, the surface smoothness of the glass will be lost, and the surface may become rough and matte.

Further, the content is optimally in the range of 2 to 7% by weight from the viewpoint of a better balance between the effect of addition and the melting property of glass.

(B ₂ O ₃ ) B ₂ O ₃ is added to the total amount of 1 to 1
It is preferable to contain 5% by weight. That is, B ₂ O ₃ exerts a flux effect with a small amount of addition to increase the meltability of the glass and improve the opacification degree of the glass.
It is suitable in that the coefficient of thermal expansion is lowered and the weather resistance is also improved.

Here, the range of the content of B ₂ O ₃ is preferably 1 to 15% by weight of the total amount, which means 1% by weight.
If it is less than the above range, the effect of addition is poor, and if it exceeds 15% by weight, the weather resistance of the glass may deteriorate. In addition, the range of 3 to 10% by weight is optimal in terms of a better balance between the effect of addition and the weather resistance of glass.

(TiO ₂ ) The total amount of TiO ₂ is 0 to 7
It is preferable to include the weight% (however, 0 weight% is not included).

Addition of a small amount of TiO ₂ improves the opacification degree of the glass, increases the meltability of the glass, improves the opacification degree of the glass, lowers the coefficient of thermal expansion, and also improves weather resistance. It is suitable in that respect.

It is also preferable in that it has a function of promoting the dispersion effect of Al ₂ O ₃ .

Here, it is preferable that the range of the content of TiO ₂ is 0 to 7% by weight (excluding 0% by weight) of the total amount, when the content exceeds 7% by weight, the glass is This is because it may be colored yellow.

The range of 1 to 5% by weight is optimal in terms of a better balance between the effect of addition and the melting property of glass.

(Further Other Glass Components) In the present invention,
Furthermore, MgO, BaO, SrO, Li ₂ O, ZrO ₂ , S
It is preferable to contain at least one oxide selected from b ₂ O ₃ , Cs ₂ O, SnO ₂ and PbO.

MgO is suitable because it has the effect of lowering the coefficient of thermal expansion of the glass, and BaO and SrO have the effect of making the glass easily meltable.
Each is 0 to 10% by weight (however, 0% by weight is not included) of the total amount.

If the content exceeds 10% by weight, the meltability of the glass may decrease with MgO and the coefficient of thermal expansion of the glass may increase with BaO and SrO. When MgO is used in combination with BaO or SrO,
It is suitable for the present invention in that a so-called solid solution effect can be obtained and the coefficient of thermal expansion of glass can be reduced while the meltability of glass is improved.

Li ₂ O is suitable for the present invention in that it exhibits the most effective glass melting action, and a suitable content is 0 to 2% by weight (however, 0% by weight is included). No). This is because if the content exceeds 2% by weight, opalescence may be reduced.

Furthermore, ZrO ₂ makes the glass opalescent,
It is preferable in that the chemical durability is remarkably improved, and the preferable content is 0 to 5% by weight (however, 0% by weight is not included) of the total amount. This is because if the content exceeds 5% by weight, the opalescence may decrease.

Sb ₂ O ₃ improves the breakage of glass bubbles, and Cs ₂ O, SnO ₂ and PbO improve the opacification degree of the glass and the chemical durability of the glass. It is suitable.

The preferred addition range for each is Sb ₂ O
₃ is 0 to 1% by weight (excluding 0% by weight), Cs
₂ O is 0 to 10% by weight (excluding 0% by weight),
SnO ₂ is 0 to 10% by weight (however, 0% by weight is not included), and PbO is 0 to 10% by weight (however, 0% by weight is not included). This is because if Sb ₂ O ₃ exceeds 1% by weight, the defoaming effect may decrease, and if SnO ₂ exceeds 10% by weight, the softening point may significantly increase. 10 for Cs ₂ O and PbO
This is because when the content of each exceeds 50% by weight, the coefficient of thermal expansion may increase, the milkiness may decrease, or the weather resistance may decrease.

In addition to the above oxides, Nb ⁵⁺ , T
It has been confirmed that even if a polyvalent oxide component composed of a ⁵⁺ , W ⁶⁺ and Mo ⁶⁺ is contained, an excellent phase separation effect can be obtained, and further, a colorant is added to the glass component. It is also suitable to color the glass to a desired color tone.

For example, Co ²⁺ , Cu in the glass component
^{2+, Ni 2+, Co 3+,} Cr 3 +, Fe 3+, Mn
It is preferable to use a coloring agent such as ³⁺ , Nb ³⁺ , Pr ³⁺ , Cr ⁶⁺ or the like because various colors can be realized.

[0055]

EXAMPLES The present invention will be specifically described with reference to the following examples.

Example 1 First, the oxide compositions shown in Table 1 were prepared, and then dry-mixed for 1 hour using a mixer to obtain 200 g of raw materials in total.

At this time, the form of the alkali metal oxide or the alkaline earth metal oxide is preferably a carbonate compound, and P ₂
The raw material form of O ₅ is dicalcium phosphate (CaHPO
_4), calcium metaphosphate _{(Ca (PO 3) 2)} , calcium phosphate _{(Ca 3 (PO 4) 2} ), dibasic sodium phosphate (NaHPO ₄₎ are preferred.

After mixing, the powder was filled in a platinum crucible and melted in a resistance heating electric furnace of air atmosphere type at a melting temperature of 1350 to 1400 ° C. for 1 to 2 hours. On the way, the molten glass was stirred several times with a platinum spatula to sufficiently homogenize the glass composition. After that, when the glass is clarified, the molten glass is poured onto a preheated stainless steel plate,
Glass was placed in an electric furnace maintained at 600 ° C. and gradually cooled.

Then, as a milky white glass obtained from the composition of the present invention, the opalescence degree of the glass was visually judged according to the following criteria.

◯: High opacity and excellent glass appearance.

Δ: Medium opacity or slight opacity of opacity is observed.

X: Low opacity, high transparency, or remarkable uneven opacity.

The sample after the slow cooling of the glass was mirror-polished and acid-corroded, and the phase-separated morphology and the rough composition were observed with a scanning electron microscope (SEM) and an analytical electron microscope. The phase was an intricate phase rich in P ₂ O ₅ —CaO and had an average particle size of about 0.4 μm.

On the other hand, the second phase was TiO ₂ —Al ₂ O ₃ -rich particles, which were uniformly and densely dispersed in the glass and had an average particle size of about 0.1 μm.

Further, there is a third phase, P ₂ which is the first phase.
O ₅ there is a -CaO phase has entered into an amorphous phase, it consisted of a total of three phases. That is, the scanning electron microscope (S
As is clear from the (EM) photograph, the glass made of the composition of the present invention is extremely uniformly and densely phase-separated, which cannot be dealt with by conventional knowledge, that is, SiO ₂ , P ₂ O ₅ ,
This is achieved from the specific addition amounts of Al ₂ O ₃ and CaO.

(Examples 2 to 11) In the same manner as in Example 1, glass was prepared using the oxide compositions shown in Table 1 and the opacities of the glass were evaluated.

For Examples 4, 6, 9, and 11, in addition to the opacification degree, the softening point was in accordance with JIS R-3104, and the annealing point and strain point were in accordance with JIS R-3103. Furthermore, the spectrophotometer was measured by Hitachi Co., Ltd., 150-20 type spectrophotometer in the form of a square of 30 mm in length and width, and a thickness of 5.0.
The measurement was performed on mm samples.

Further, the liquidus temperature of the glass was determined only in Example 6. That is, small glass pieces were crushed in an agate mortar to prepare glass powder having a particle size of 0.2 to 0.6 μm. Then, put 3 g of this powder on a platinum plate, and
The temperature was maintained at 50, 800, 850, 900 and 950 ° C. for 20 hours in an electric furnace. As a result, it was confirmed that the glass of Example 6 had a crystallization temperature of 900 ° C. or lower and had a lower liquidus temperature than the conventional glass described in JP-A-63-265841. .

(Comparative Examples 1 to 4) Glass was made from the composition shown in Table 2 which deviates from the content of the present invention, and the opalescence was evaluated in the same manner as in Example 1. As a result, as shown in Table 2, in the glass which is out of the content range of the composition of the present invention, the transparency is high and the opacities are low, or the opacities of the opacities are remarkably observed. It lacked in aesthetics.

[0070]

[Table 1]

[Table 2]

[0071]

EFFECTS OF THE INVENTION According to the present invention, it does not contain a significant amount of a fluorine compound, is safe and easy to produce, has no concern about air pollution, human health, agricultural products, and has a high opacification degree and can be melted at low temperature. It has become possible to provide a milky white glass composition.

The light transmittance of the glass made from the composition of the present invention at 350 to 700 nm is 0.02.
The range is from 0.18% to 0.18%, while that of JP-A-50-5
As described in Japanese Patent No. 1513, the conventional milky white glass has a transmittance of at least about 1 to 5%,
It was confirmed that the glass made from the milky white glass composition of the present invention exhibits an excellent light blocking effect including ultraviolet rays.

Further, the glass made from the composition of the present invention has a glass softening point, an annealing point and a strain point which are equal to or lower than those of industrially mass-produced soda-lime glass, and the same. It also has the advantage that glass can be pressed or blown under the molding conditions.

Therefore, since the melting temperature of the glass is lowered, specifically, the melting at 1400 ° C. or less is made possible, the problem of corrosion of the glass melting furnace is solved.

Further, in the present invention, it is considered that the content of Al ₂ O ₃ is high, but the coefficient of thermal expansion of glass is lower than that of soda-lime glass (about 90 × 10 −7 / ° C.),
It also has advantages such as improved thermal shock and reduced annealing time.

In addition, according to the present invention, the following unique effects can be obtained, and the present invention provides a milky white glass which has not been used in the past, including the use of plate glass, cosmetics, pharmaceuticals,
It is expected to be widely used in containers for foods, decorative glass, etc.

(1) Due to the high opacification degree, light, especially ultraviolet rays is sufficiently blocked, and the effect of preserving the contents in the container is remarkably improved.

(2) Since it can be melted at a low temperature and has good thermal shock resistance, it is highly adaptable to molding of complicated shapes and large-scale containers.

(3) By increasing the ultraviolet protection effect, it is possible to prevent deterioration of indoor wallpaper, curtains, etc. when used for window glass or the like.

(4) Due to its high surface smoothness, it is crushed into a certain shape to obtain a polyester resin, a polyacrylic resin,
It can be easily added to an epoxy resin or the like to be used as an additive for milky white glass particles.

Claims (9)

[Claims] 1. A composition for opalescent glass, which comprises the following composition: SiO ₂ 35 to 65 wt% _P 2 _O 5 3.5 to 10 wt% _Al 2 _O 3 5.5 to 15 wt% CaO 3.0-15 wt% _2. The composition for opalescent glass according to claim 1, wherein the content of SiO ₂ is 40 to 60 (excluding 60% by weight)% by weight. 3. The opalescent glass composition according to claim 1, wherein the content of SiO ₂ is 45 to 55 (excluding 55% by weight)% by weight. 4. The composition for opalescent glass according to claim 1, wherein the composition contains 4 to 15% by weight of Na ₂ O. 5. The composition is added with K ₂ O in an amount of 1 to 10% by weight.
The composition for opalescent glass according to any one of claims 1 to 4, comprising: 6. The composition according to claim 1, wherein the composition comprises Z
2 to 10% by weight of nO is contained.
The composition for opalescent glass according to any one of 1 to 5. 7. The composition for opalescent glass according to claim 1, wherein the composition contains 1 to 15% by weight of B ₂ O ₃ . 8. TiO ₂ is added to the composition in an amount of 0 to 7% by weight.
The composition for milky white glass according to any one of claims 1 to 7, wherein the composition contains (but does not contain 0% by weight). 9. A composition comprising MgO, BaO, SrO,
Li ₂ O, ZrO ₂ , Sb ₂ O ₃ , Cs ₂ O, Sn
The opalescent glass composition according to claim 1, further comprising at least one oxide selected from O ₂ and PbO.