KR20160002774A - Float bath roof member, float plate glass production device using same, and method for producing float plate glass - Google Patents

Abstract

A float bath loop member in which creep deformation during use is suppressed, a float plate glass manufacturing apparatus using the same, and a float plate glass manufacturing method are provided. Wherein at least 90% by mass of the crystal phase is a mullite phase, and the total content of sodium oxide, potassium oxide, titanium oxide and iron oxide is 2% by mass or less, and coarse particles having an average crystal grain size D50 of 1.0 mm or more And a fine particle having an average crystal grain size D50 of 0.1 mm or less, wherein the mass ratio of the coarse particles and the fine particles is 85 to 60 mass% and 15 to 40 mass%.

Description

Technical Field [0001] The present invention relates to a float glass member, a float glass member, a float glass member, a float glass member, a float glass member, a float glass member,

The present invention relates to a float bath loop member, a float plate glass manufacturing apparatus using the float glass member, and a manufacturing method of the float glass plate.

A float method is known as one method for manufacturing a plate glass. In this float method, (1) a molten glass is introduced into a bath containing molten tin called a float bath,

(2) The molten glass is continuously conveyed from the upstream side to the downstream side on the molten tin,

(3) is discharged from the float bath while cooling the molten glass to produce a plate glass.

Normally, a ceiling portion called a float bath loop is provided at an upper portion of the float bath. This float bath loop is composed of refractory bricks hooked to a plurality of hanger hinges (that is, the side facing the float bath), that is, float bath loops have a suspended structure (see Patent Documents 1 and 2).

Japanese Patent Application Laid-Open No. 6-239631 Japanese Patent Application Laid-Open No. 2001-139336

Refractory bricks used in float bath loops are relatively lightweight and have heat resistance that can be used for a long time at a high temperature of up to about 1000 ° C and the amount of evaporated water that can be a defect of glass produced at high temperature is small (Al ₂ O ₃ ) -silica (SiO ₂ ) -based refractory bricks can be used as the refractory bricks, and a silymalitic refractory brick can be used in various molding methods and can be formed into various shapes Lt; / RTI >

Creep deformation may be seen in the refractory brick constituting the float bath loop in cold repair of the float bath or the like. Since the refractory brick constituting the float bath loop is of a hanging structure which is engaged with the hanger, if creep deformation of the refractory brick progresses, there is a fear of falling off from the hanger and falling. Further, when the creep strain is excessively advanced, cracks may be generated in the refractory brick.

The creep deformation of the refractory brick is more advanced as the temperature is higher. Therefore, in the case of molding a glass having a higher viscosity into a plate shape, or when molding a glass having the same composition into a thin plate glass, , More preferably not more than 0.5 mm, and more preferably not more than 0.3 mm, when the temperature of the atmosphere in the float bath is raised, the problem becomes more serious.

Further, since the amount of creep deformation increases with time in accordance with the holding time in a high-temperature environment, this is a problem particularly in terms of using the float bath for a long period of time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a member for a float bath loop in which creep deformation is suppressed when used under a high temperature environment, a float plate glass manufacturing apparatus using the same, and a float plate glass manufacturing method.

In order to achieve the above object, the present invention provides an alumina-silica-based sintered body in which at least 90% by mass of a crystal phase is a mullite phase and the total content of sodium oxide, potassium oxide, titanium oxide and iron oxide is 2% The coarse particles having an average crystal grain size D50 of 1.0 mm or more and the fine particles having an average crystal grain size D50 of 0.1 mm or less, wherein the mass ratio of the coarse particles and the fine particles is 85 to 60 mass% and 15 to 40 mass% Lt; / RTI >

The float bath loop member in one embodiment of the present invention preferably has a creep speed of 1 x 10 < ^-8 > / sec or less at a bending creep test (1300 DEG C, load of 3.5 MPa) at a sample size of 25 mm x 15 mm x 100 mm.

It is also preferable that the float bath loop member in one embodiment of the present invention has a 1000-hour creep strength of 6 MPa or more at a bending creep test (1300 ° C) at a sample size of 25 mm × 15 mm × 100 mm.

Further, in the float bath loop member according to one embodiment of the present invention, it is preferable that the coarse particles and the fine particles include mullite particles, and the mullite particles are electroless mullite particles.

In the float bath loop member according to one embodiment of the present invention, it is preferable that the content of the crystal phase other than the mullite phase, that is, the corundum and the cristobalite is 10 mass% or less with respect to the crystal phase of the alumina-silica-based sintered body.

Further, in the float bath loop member according to one embodiment of the present invention, it is preferable that the crystalline phase other than the mullite phase is one of corundum and cristobalite, and the content ratio of corundum is high.

In the apparatus for manufacturing float glass according to one embodiment of the present invention, there is provided a float glass manufacturing apparatus comprising a float bath containing molten tin therein and a float bath loop provided on the float bath,

Wherein the float bath loop is constituted by the float bath loop member of the present invention.

According to another aspect of the present invention, there is provided a method of manufacturing a float plate glass including manufacturing a floated plate glass using the apparatus for manufacturing float glass according to an embodiment of the present invention.

In the method of manufacturing a float glass according to one embodiment of the present invention, it is preferable that the float glass is a float glass for display, and the thickness of the float glass is 0.7 mm or less.

The float bath loop member of the present invention is suppressed from creep deformation when used under a high temperature environment.

This reduces the likelihood that the float bath loop member tends to fall off from the hanger and the float bath loop member is cracked at the time of manufacturing the glass plate.

This feature is also suitable for the production of float glass which is required to raise the atmospheric temperature in the float bath, such as when producing a glass plate using a highly viscous glass such as alkali-free glass or when producing thin glass .

With this feature, the float bath is used over a long period of time and is suitable for use in the production method of float glass.

1 is a graph showing a relationship between a load and a fracture time in the bending creep test.

Hereinafter, a float bath loop member and a float glass plate manufacturing apparatus using the float bath loop member according to an embodiment of the present invention will be described.

A float bath loop member in an embodiment of the present invention includes an alumina-silica-based sintered body and is suspended in a hanger by a hanger on the float bath like refractory bricks in Patent Documents 1 and 2 to form a float bath loop . Normally, a plurality of float bath loop members are disposed on the float bath to form float bath loops. As a result, this member is required to be combined with an insertion part or another member for supporting the suspension by a hanger, and good formability is required.

The float bath loop member of the present invention comprises an alumina-silica-based sintered body having a total amount of sodium oxide, potassium oxide, titanium oxide, and iron oxide of 2 mass% or less in each of 90 mass% Coarse particles having a crystal grain size D50 of 1.0 mm or more and fine particles having an average crystal grain size D50 of 0.1 mm or less, and the mass ratio of the coarse particles and the fine particles is 85 to 60 mass% and 15 to 40 mass%.

As described above, among the alumina-silica-based sintered bodies, silylated sintered bodies have been mainly used as float bath loop members. The sillimanite-based sintered body is one kind of high aluminous sintered brick using a raw material of relatively high purity, and a mullite, corundum and cristobalite are mixed as a crystal phase.

Of the crystalline phases of the alumina-silica-based sintered body, the alumina corundum is slowly plastic-deformed when used under a high temperature environment of 1200 占 폚 or higher. On the other hand, cristobalite undergoes phase transformation (phase transformation) at a temperature of 1400 ° C or lower and is transformed into tridimite, which causes cracking due to volume change. As a result, sintered bodies containing many of these crystal phases are creep deformed due to plastic deformation or cracking.

On the other hand, mullite does not cause plastic deformation or phase transformation (phase transformation) even when used in a high temperature environment of 1200 ° C or higher. Therefore, the float bath loop member of the present invention, in which 90% by mass or more of the crystal phase of the alumina-silica-based sintered body is a mullite phase, can be used even when used in a high temperature environment of 1200 ° C or higher, . As a result, creep deformation is small.

Further, as will be described later in detail, the float bath loop member of the present invention is composed of two types of alumina-silica-based sintered bodies (coarse particles, fine particles) having different average crystal grain sizes. At least 90% by mass of the crystal phase of each of these two kinds of alumina-silica-based sintered bodies is a mullite phase.

When the proportion of the mullite phase occupying the crystal phase of the alumina-silica-based sintered body is lower than 90 mass%, cracking occurs due to plastic deformation of the crystalline phase (corundum or cristobalite) other than the mullite phase or volume change due to phase transformation Creep strain increases.

The float bath loop member of the present invention may contain crystal phases other than the mullite phase, that is, corundum and cristobalite up to 10 mass% of the crystal phase of the alumina-silica-based sintered body. In this case, the crystal phase other than the mullite phase may be either corundum or cristobalite. However, when corundum is used in a temperature region of 1200 占 폚 or more, creep deformation does not occur, so that the content ratio of corundum is preferably high.

In the float bath loop member in one embodiment of the present invention, the proportion of the mullite phase occupying the crystal phase of the alumina-silica-based sintered body is more preferably 95 mass% or more, and further preferably 97 mass% or more.

When the alumina-silica-based sintered body contains sodium oxide, potassium oxide, titanium oxide or iron oxide, it reacts with silica (SiO ₂ ) in the sintered body to form a glass phase when used in a high temperature environment of 900 ° C or higher. When such a glass phase is formed, the sintered body is softened, so that creep deformation becomes large. Therefore, the alumina-silica-based sintered body used in the float bath loop member preferably has a low content of these components.

The float bath loop member according to one embodiment of the present invention has a total content of sodium oxide, potassium oxide, titanium oxide and iron oxide in an alumina-silica-based sintered body of 2 mass% or less, The sintered body is not softened and creep deformation is small.

As described above, the float bath loop member of the present invention is composed of two types of alumina-silica-based sintered bodies (coarse particles, fine particles) having different average crystal grain sizes. The total content of sodium oxide, potassium oxide, titanium oxide and iron oxide in each of these two kinds of alumina-silica-based sintered bodies is 2 mass% or less.

The float bath loop member in one embodiment of the present invention preferably has a total content of sodium oxide, potassium oxide, titanium oxide and iron oxide in the alumina-silica-based sintered body of 1.5 mass% or less, more preferably 1 mass% or less Do.

The float bath loop member of the present invention comprises coarse particles each having an average crystal grain size D50 of not less than 1.0 mm and fine particles having an average crystal grain size D50 of not more than 0.1 mm, each including an alumina-silica-based sintered body.

When a block-shaped alumina-silica-based sintered body such as a float bath loop member is produced, it is difficult for the sintered body to have an anisotropy in the rate of dimensional change during sintering, and thus the raw material for the sintered body has a small particle size distribution, It is usually used. As a result, the particle size distribution of the crystal grains constituting the block-shaped alumina-silica-based sintered body thus produced is small, that is, the crystal grain size is somewhat uniform.

However, if the particle size distribution of the crystal grains constituting the block-shaped alumina-silica-based sintered body is small, that is, if the crystal grain size is somewhat uniform, the following problems arise.

When all of the crystal grains constituting the block-shaped alumina-silica-based sintered body have a large crystal grain size, a gap is generated between crystal grains. As a result, the crystal grains are not sufficiently bonded to each other, and creep deformation of the alumina-silica-based sintered body becomes large. Further, the creep strength of the alumina-silica-based sintered body is lowered.

On the other hand, when the crystal grains constituting the block-shaped alumina-silica-based sintered body are all small in crystal grain size, gaps do not occur between crystal grains, but strain and shrinkage during sintering are increased. As a result, there is a possibility that the sintered body is potentially cracked and broken at the time of use.

The float bath loop member of the present invention is characterized in that the crystal grains constituting the alumina-silica-based sintered body are composed of coarse grains having an average crystal grain size D50 of 1.0 mm or more and fine grains having an average crystal grain size D50 of 0.1 mm or less, The above-mentioned problem in the alumina-silica-based sintered body of the present invention is solved. That is, by including coarse particles, deformation and shrinkage during sintering are not increased, and potential cracking does not occur inside the sintered body. This eliminates the possibility of breakage during use.

On the other hand, since the fine particles are filled in the gaps between the coarse particles, the crystal grains are strongly bonded to each other. As a result, creep deformation of the sintered body is reduced. Further, creep strength of the sintered body is improved.

However, in order to achieve the above effect, the ratio of the coarse particles to the fine particles in the alumina-silica-based sintered body must satisfy the following specific ranges.

In the float bath loop member of the present invention, the mass ratio of the coarse particles and the fine particles in the alumina-silica-based sintered body is 85 to 60 mass% and 15 to 40 mass%, respectively.

When the mass ratio of the fine particles in the alumina-silica-based sintered body exceeds 40 mass% (mass ratio of coarse particles is less than 60 mass%), deformation or shrinkage during sintering becomes large and the yield during production is reduced. In addition, there is a possibility that the sintered body is potentially cracked and broken at the time of use.

On the other hand, when the mass ratio of the fine particles in the alumina-silica-based sintered body is less than 15 mass% (mass ratio of the coarse particles is more than 85 mass%), the crystal grains are not sufficiently bonded to each other and creep deformation of the alumina- . Further, the creep strength of the alumina-silica-based sintered body is lowered.

In the float bath loop member in one embodiment of the present invention, the mass ratio of the coarse particles and the fine particles in the alumina-silica-based sintered body is preferably 75 to 70 mass% and 25 to 30 mass%, respectively.

The alumina-silica-based sintered body in which the mass ratio of the coarse particles and the fine particles satisfy the above-described range can be produced by the following procedure.

Mullite particles A having an average particle diameter D50 of 1.0 mm or more and mullite particles B having an average particle diameter D50 of 0.1 mm or less are prepared. The mullite particles A and B have a total content of 2 mass% or less of sodium oxide, potassium oxide, titanium oxide, and iron oxide.

The mullite particles A and the mullite particles B are compounded so that their mass ratio becomes 85 to 60 mass% and 15 to 40 mass%. The resulting mixture is filled into a mold having a predetermined shape according to the shape of the float bath loop member and is sintered by heating to a predetermined temperature, for example, 1500 DEG C or higher.

As the mullite particles A and B, the use of the electric molten mullite particles is preferable because the content of impurities such as sodium oxide, potassium oxide, titanium oxide and iron oxide is lowered. The electric molten mullite particles are obtained by crushing the electric molten mullite to a predetermined size.

The float bath loop member according to one embodiment of the present invention is suppressed from creep deformation when it is used under a high temperature environment. In this specification, the creep rate in the bending creep test is used as an index of creep strain. Specifically, the creep rate in the bending creep test (1300 占 폚, load: 3.5 MPa) described in the later-described embodiments is preferably 1 占^10-8 / sec or less, more preferably 0.5 占^10-8 / sec or less And more preferably 0.1 x 10 < ^-8 > / sec or less.

Further, the float bath loop member according to one embodiment of the present invention has a high creep strength when used under a high temperature environment. More specifically, the 1000-hour creep strength at the bending creep test (1300 ° C) described in Examples described later is preferably 6 MPa or more, more preferably 8 MPa or more, and further preferably 10 MPa or more.

The maximum stress applied to the float bath loop member at the time of use varies depending on the conditions of use and the design of the peripheral member, but is about 0.1 to 1.0 MPa. Therefore, the float bath loop member in one embodiment of the present invention has a sufficient creep strength against the stress applied at the time of use.

The dimensions and shape of the float bath loop member in one form of the present invention are appropriate depending on the arrangement of the respective members in the float bath loop and the like. For example, it is a rectangular parallelepiped having a length of about 30 cm, a width of 5 to 8 cm, and a height of 6 to 10 cm. Grooves for engaging with the hanger are formed at both ends of the float bath loop member.

Next, an apparatus for manufacturing a float glass plate according to an embodiment of the present invention will be described.

An apparatus for manufacturing float glass according to an embodiment of the present invention includes a float bath containing molten tin therein and a float bath loop provided on the float bath. This float bath loop is constituted by the float bath loop member of the present invention.

As described above, the float bath loop member of the present invention has suppressed creep deformation when used under a high-temperature environment, and has a high creep strength when used under a high-temperature environment.

Thereby, the float bath loop member can be used over a long period of time without the risk of falling off from the hanger and falling.

In addition, the above-mentioned characteristic of the float bath loop member of the present invention, that is, creep deformation when used under a high temperature environment is suppressed, and the creep strength when used under a high temperature environment is high, It is more effective in one case.

Therefore, the apparatus for producing float glass in one embodiment of the present invention is preferably used in the case of producing a plate glass using a glass having a higher viscosity, or in the case of producing a plate glass having a thin thickness even with glass of the same composition do.

As a specific example of the former, a case of producing a plate glass using a highly viscous glass such as a high-precision display glass provided in a manufacturing process including a step of exposing to a high temperature can be mentioned.

As a specific example of the latter, a case of producing a plate glass having a thickness of 0.7 mm or less, more preferably 0.5 mm or less, further preferably 0.3 mm or less can be mentioned.

A method of manufacturing a float glass according to an embodiment of the present invention comprises the steps of introducing a molten glass into a bath containing molten tin called a float bath and continuously conveying the molten glass from the upstream side to the downstream side on the molten tin, And then discharged from the float bath while cooling to produce a plate glass. In the method of manufacturing a flute plate glass according to an embodiment of the present invention, since the float bath loop member of the present invention is used, it can be stably manufactured in the long term.

<Examples>

Hereinafter, the present invention will be described in detail by way of examples, but the present invention is not limited to these examples.

(Example 1, Comparative Examples 1 and 2)

An alumina-silica-based sintered body having the composition shown in the following table was prepared as a sample for bending creep test. The dimensions of the test sample were 25 mm x 15 mm x 100 mm.

The alumina-silica-based sintered body is obtained by blending mullite particles A having an average particle diameter D50 of 1.0 mm or more and mullite particles B having an average particle diameter D50 of 0.1 mm or less at a predetermined blending ratio, . The mullite particles A and B are obtained by crushing an electric molten mullite and dividing it into mullite A and B according to the particle size. As a result, coarse particles (having an average crystal grain size D50 of 1.0 mm or more) and fine particles (having an average crystal grain size D50 of 0.1 mm or less) constituting the alumina-silica system sintered body have the same ratio of mullite phase and impurity content It is a figure. The content of impurities in the table is the total content of sodium oxide, potassium oxide, titanium oxide and iron oxide.

In the bending creep test, the creep speed (/ sec) was measured at a temperature of 1300 캜 with the load being 2.5 MPa and 3.5 MPa. The results are shown in the following table.

In the bending creep test, the relationship between the load and the breaking time was evaluated. The results are shown in Fig.

From the results shown in Table 2, the alumina-silica sintered body of Example 1 having a mullite phase ratio of at least 90% by mass in the crystal phase had an alumina-silica sintered body of Comparative Examples 1 and 2 having a mullite phase ratio of less than 90 mass% It was confirmed that the creep speed was low and creep deformation was small. 1, the alumina-silica sintered body of Example 1 has a creep rate lower than that of the alumina-silica sintered bodies of Comparative Examples 1 and 2 in which the ratio of the mullite phase in the crystal phase is less than 90 mass% Less was confirmed. From the results shown in Fig. 1, it was confirmed that the alumina-silica sintered bodies of the Examples had higher creep strength than the alumina-silica sintered bodies of Comparative Examples 1 and 2.

(Example 2, Comparative Example 3)

In Example 2, a float bath loop member was produced by using an alumina-silica sintered body having the same composition as in Example 1. [ This was installed in a conventional float bath loop. As Comparative Example 3, a conventional silylmanite refractory brick was provided as a float bath loop member. The dimensions and shape of the float bath loop member are as described above. The maximum stress applied to the float bath loop member at the time of use is as described above. The refractory brick of Comparative Example 3 was warped downward at the center portion of the float bath and the creep deformation was confirmed by visual observation after 4 weeks at the ambient temperature of 1300 占 폚. Further, many cracks were generated in the bottom surface of the refractory brick. On the contrary, in the float bath loop member of Example 2, creep deformation and cracks were not observed.

The present application is based on Japanese Patent Application No. 2013-087224 filed on April 18, 2013, the contents of which are incorporated herein by reference.

Claims (9)

Wherein at least 90% by mass of the crystal phase is a mullite phase, and the total content of sodium oxide, potassium oxide, titanium oxide and iron oxide is 2% by mass or less, and coarse particles having an average crystal grain size D50 of 1.0 mm or more And fine particles having an average crystal grain size D50 of not more than 0.1 mm, and each having a mass ratio of 85 to 60 mass% and 15 to 40 mass%. The float bath loop member according to claim 1, wherein a creep rate at a bending creep test (1300 占 폚, load: 3.5 MPa) at a sample size of 25 mm 占 15 mm 占 100 mm is 1 占 10 ^-8 / sec or less. The float bath loop member according to claim 1 or 2, wherein the 1000-hour creep strength at a bending creep test (1300 ° C) at a sample size of 25 mm × 15 mm × 100 mm is 6 MPa or more. The float bath loop member according to any one of claims 1 to 3, wherein the coarse particles and the fine particles comprise mullite particles, and the mullite particles are electrically molten mullite particles. The sintered body according to any one of claims 1 to 4, wherein the crystalline phase other than the mullite phase, that is, the content ratio of corundum and cristobalite is 10 mass% or less with respect to the crystal phase of the alumina- Loop member. The float bath loop member according to any one of claims 1 to 5, wherein the crystal phase other than the mullite phase is any one of corundum and cristobalite, and the content ratio of corundum is high. 1. A float glass manufacturing apparatus comprising a float bath in which molten tin is received therein and a float bath loop provided on the float bath,
Characterized in that the float bath loop is constituted by the float bath loop member according to any one of claims 1 to 6. A float plate glass manufacturing method comprising manufacturing a float plate glass using the apparatus for manufacturing float glass according to claim 7. The float plate glass manufacturing method according to claim 8, wherein the float glass is a float glass for display, and the thickness of the float glass is 0.7 mm or less.

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