JP2015193522A - Kaolin raw material for glass manufacture and manufacturing method of glass fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a glass fiber capable of adjusting a foam layer state which is formed on a glass molten liquid surface.SOLUTION: The manufacturing method of glass fiber is characterized in that a kaolin raw material for glass manufacture having equal to or more than 300 ppm of a chemical oxygen demand (COD) is used for preparing a raw material batch, and the prepared raw material batch is melted, and then molded into a fibrous state.

Description

  The present invention relates to a kaolin raw material for glass production and a method for producing glass fiber using the same.

  In general, glass fibers used for a composite material are manufactured by melting glass raw materials in a glass melting furnace, supplying the glass raw materials to a molding apparatus called bushing, and continuously molding and spinning.

  The glass raw material supplied to the inside of the glass melting furnace is heated and melted from above by combustion of the burner. In addition, the glass may be heated by energizing the glass with an electrode provided at the bottom of the melting furnace.

Japanese Patent Laid-Open No. 2002-316832

When the glass raw material is melted, a foam layer may be generated on the surface of the glass melt. This foam layer is caused by SO ₂ gas generated by decomposition of sulfate contained in the glass raw material and sulfate added as a fining agent. The foam layer contributes to stabilization of the glass melting, and prevents the glass melt from flowing quickly and makes it easy to obtain a glass free from striae and irregularities.

  However, if the foam layer is too thick, heat from the burner is not easily transmitted to the glass, and a large amount of energy is required for melting the glass.

  The subject of this invention is providing the raw material which can adjust the state of a foam layer, and the manufacturing method of glass fiber using the same.

  As a result of earnest research, the present inventors have found that a certain kind of kaolin raw material contains a large amount of reducing components such as carbon, and that this kind of raw material can be used to control the state of the foam layer, and proposes as the present invention. Is. Patent Document 1 describes that a reducing agent such as carbon is added to a glass raw material in order to adjust the valence of Fe ions. However, this document does not describe the relationship between the reducing agent and the foam layer.

That is, the kaolin raw material for glass production of the present invention is characterized by having a chemical oxygen demand (COD) of 300 ppm or more. Here, the kaolin raw material is a mineral mainly composed of kaolinite (Al ₂ O ₃ · 2SiO ₂ · 2H ₂ O). The chemical oxygen demand (COD) is an index representing the content of the reducing component, and refers to a value calculated as C (carbon) by measuring a value of oxygen consumption by potassium dichromate.

The sulfate is usually decomposed at a high temperature of 1400 ° C. or higher, and a foam layer is formed on the surface of the glass melt by the generated SO ₂ gas or the like. However, when the above-mentioned kaolin raw material is added to the glass raw material, the decomposition reaction of sulfate is promoted by the action of carbon contained in the raw material, and SO ₂ gas is generated at a low temperature of 800 to 1000 ° C. As a result, the amount of sulfate decomposed at a high temperature of 1400 ° C. or more is reduced, and the foam layer can be made thin.

  FIG. 1 is a photograph showing foaming behavior of E glass using kaolin having a COD of 270 ppm, and FIG. 2 is a photograph showing foaming behavior of E glass using kaolin having a COD of 1450 ppm. As shown in FIG. 2, with kaolin having a high COD, the sulfate layer added as a fining agent in the E glass batch decomposed at a low temperature of 800 ° C. to 1000 ° C. As a result, a foam layer cannot be confirmed at 1400 ° C. or higher.

  It is preferable that the kaolin raw material of this invention is used for manufacture of glass fiber.

Glass fiber generally uses mirabilite (Na ₂ SO ₄ ) as a fining agent. For this reason, a bubble layer resulting from SO ₂ gas generated by decomposition of sodium sulfate is formed on the surface of the glass melt. Then, if the kaolin raw material of this invention is added to a raw material batch, the foam layer formed in the glass melt surface can be made thin, and the heating efficiency by a burner can be improved.

  The glass fiber manufacturing method of the present invention is characterized in that a raw material batch prepared using the above-described kaolin raw material is melted and formed into a fiber shape.

  According to the said structure, it becomes easy to control the state of a foam layer, and it becomes possible to make stable fusion | melting and high energy efficiency compatible.

  In the present invention, the molten glass is supplied to the bushing, continuously drawn out in a filament form from a number of bushing nozzles provided on the bottom surface of the bushing, and then applied with a treatment agent on the drawn monofilament and focused. It is preferable to mold the molten glass into a fiber.

In the present invention, on an oxide _basis, SiO 2 42-67 _{mass%, Al} 2 O 3 8 to 26 wt%, and _R 2 O (where, R represents, Li, at least one of Na and K) 0 It is preferable to produce glass fibers containing ~ 2% by weight.

In the present invention, in mass percent on the oxide _{basis, SiO 2 52~62%, Al 2} O 3 10~16%, B 2 O 3 0~8%, 0~5% MgO, CaO 16~25% and It is preferable to produce glass fibers containing R ₂ O (where R is at least one of Li, Na and K) 0 to 2% and SO ₃ 0.01 to 1%.

  In this invention, it is preferable to manufacture the glass fiber which consists of E glass. Here, the E glass means a composition defined by ASTM D578-05 4.2.2.

This is an observation of the foaming behavior of an E glass batch prepared using a kaolin raw material having a COD of 270 ppm. (A) is 1300 ° C., (b) is 1350 ° C., (c) is 1400 ° C., (d) is 1450 ° C and (e) are photographs showing the state at 1500 ° C, respectively. This is an observation of the foaming behavior of an E glass batch prepared using a kaolin raw material having a COD of 1450 ppm. (A) is 1300 ° C., (b) is 1350 ° C., (c) is 1400 ° C., (d) is 1450 ° C and (e) are photographs showing the state at 1500 ° C, respectively. It is a graph showing a release behavior of the SO ₂ gas from the batch and molten glass. It is a graph which shows the change of the furnace bottom temperature of a melting furnace. Is a graph showing changes in SO ₃ dissolved amount in the glass melt.

  The present invention is described in detail below. In the following description, “%” means mass% unless otherwise specified.

  The kaolin raw material for glass production of the present invention contains a large amount of a reducing component (carbon or the like). Specifically, in the kaolin raw material of the present invention, the content of the reducing component represented by chemical oxygen demand (COD) is 300 ppm or more. The preferable value of COD is 500 ppm or more, 1000 ppm or more, particularly 1300 ppm or more. If the COD is too low, the effect of promoting the decomposition of sulfate is reduced, and it becomes difficult to adjust the state of the foam layer.

  Next, the manufacturing method of the glass fiber of this invention using the said kaolin raw material is demonstrated.

  First, glass raw materials are prepared so as to obtain a target composition to obtain a raw material batch.

The target composition is mass% on the basis of oxide, SiO ₂ 42 to 67%, Al ₂ O ₃ 8 to 26%, and R ₂ O (where R is at least one of Li, Na and K) 0 glass composition containing 2%, in particular _{SiO 2 52~62%, Al 2 O} 3 10~16%, B 2 O 3 0~8%, 0~5% MgO, CaO 16~25% and _R 2 O ( However, R is preferably formulated so as to have a so-called E glass composition containing 0 to 2% of Li, Na and K) and 0.01 to 1% of SO ₃ . The reason why each component is limited to the above range will be described below. In the following description, “%” means mass%.

SiO ₂ is a glass network former. The content is 42 to 67%, preferably 52 to 62%, more preferably 53 to 60%, and particularly preferably 55 to 60%. If the content of SiO ₂ is too low, the mechanical strength of the glass fiber may be too low. If the content of SiO ₂ is too high, the viscosity of the glass melt becomes too high, which may make melting and molding difficult.

Al ₂ O ₃ is a component that improves the weather resistance and mechanical strength of the glass fiber. Its content is 8 to 26%, preferably 10 to 18%, more preferably 13 to 16%. If the content of Al ₂ O ₃ is too low, the glass melt may be easily devitrified. If the Al ₂ O ₃ content is too high, the viscosity of the glass melt will be too high, which may make melting and molding difficult.

B ₂ O ₃ is a component that lowers the melting temperature and the spinning temperature of the glass while lowering the viscosity of the glass melt. Its content is preferably 0 to 25%, 1 to 10%, in particular 5 to 9%. If the content of B ₂ O ₃ is too high, the chemical durability of the glass fiber may be too low. Moreover, since the volatilization amount from a glass melt increases, it becomes difficult to manufacture glass fiber with a stable composition.

MgO and CaO are components that improve the meltability of glass. The content of MgO is preferably 0 to 15%, 0 to 10%, particularly 0.1 to 4%. The CaO content is preferably 9 to 35%, 16 to 25%, and particularly 18 to 25%. If the content of CaO is too low, the viscosity of the glass melt becomes too high, and melting and spinning may be difficult. If the content of CaO is too high, crystals of wollastonite (CaO.SiO ₂ ) may be easily precipitated. If the content of MgO becomes too high, crystals of diopside (CaO · MgO · 2SiO ₂ ) may be easily precipitated.

R ₂ O (where R is at least one of Li, Na, and K) is a component that improves the meltability and spinnability of the glass. The total content of R ₂ O is 0 to 2%, preferably 0.3 to 2%. If the content of R ₂ O is too high, the mechanical strength of the glass fiber may be too low. In addition, the electrical resistance value of the glass fiber decreases, making it unsuitable for electrical insulation.

In addition to the above, various components can be contained. For example _{SrO, BaO, ZrO 2, As} 2 O 3, SnO 2, ZnO 2, Sb 2 O 3, SO 3, Cl 2, H 2 O, He, may contain Ni or the like.

  The glass raw material to be used is illustrated. In addition, although a raw material batch may be comprised only with these raw materials, you may use glass cullet together.

  Silica or the like can be used as the silicon source.

As the aluminum source, kaolin, alumina or the like can be used. In particular, kaolin having a COD of 300 ppm or more (hereinafter referred to as high COD kaolin) is preferably used as an essential component. The characteristics of the high COD kaolin raw material are as described above, and the description is omitted here. Moreover, you may adjust suitably the usage-amount of high COD kaolin according to the state of a foam layer. For example, when the thickness of the foam layer is not so large, the use ratio of high COD kaolin may be reduced and the amount may be supplemented with ordinary kaolin (kaolin having a COD of less than 300 ppm), alumina, or the like. The ratio of the high COD kaolin to the aluminum raw material is preferably 10% or more, particularly 40 to 100% in terms of Al ₂ O ₃ .

As a boron source, colemanite (alias: boroborite, 2CaO · 3B ₂ O ₃ · 5H ₂ O), boric acid (B ₂ O ₃ · 3H ₂ O), 5 water borax (Na ₂ O · 2B ₂ O ₃ · 5H ₂ O) or the like can be used.

As an alkaline earth metal source, carbonates of alkaline earth metals such as calcium carbonate, dolomite (MgO · CaO · 2CO ₂ ) and the like can be used.

An alkali metal carbonate such as sodium carbonate (Na ₂ CO ₃ ) can be used as the alkali metal source.

Examples of the sulfate source include alkali metal or alkaline earth metal sulfates such as sodium sulfate (Na ₂ SO ₄ ) and calcium sulfate (CaSO ₄ ).

  In this way, a raw material batch is produced. The raw material batch is preferably prepared so that the overall COD is 100 ppm or more, particularly 300 to 700 ppm.

  Next, the prepared raw material batch is put into a glass melting furnace to be vitrified, melted and homogenized. The melting temperature is preferably about 1500 to 1600 ° C.

  Subsequently, molten glass is spun and formed into glass fibers. More specifically, molten glass is supplied to the bushing. The molten glass supplied to the bushing is continuously drawn out in filament form from a number of bushing nozzles provided on the bottom surface. Various processing agents are applied to the monofilaments drawn in this way, and glass fibers are obtained by focusing each monofilament.

  The glass fiber formed in this way is processed into chopped strands, yarns, rovings, etc. and used for various purposes. The chopped strand is obtained by cutting glass fibers (strands) obtained by focusing glass monofilaments into a predetermined length. A yarn is a twisted strand. Roving is a combination of a plurality of strands wound in a cylindrical shape.

Hereinafter, the present invention will be described in detail based on specific examples.
(Example 1)
Using different raw material batches of COD, investigated the foaming behavior of SO ₂ gas released from the glass.

First, kaolin having a COD amount shown in Table 1 was used as an aluminum source, and E glass (SiO ₂ 53% by mass, Al ₂ O ₃ 15%, B ₂ O ₃ 7%, MgO 3%, CaO 20%, TiO in mass%) ₂ 0.3%, Na ₂ O 1%, K ₂ O 0.2%, Fe ₂ O ₃ 0.1%, SO ₃ 0.2%), and a raw material batch was prepared.

  Next, the gas release behavior at 600 ° C. to 1600 ° C. was evaluated for each raw material batch using a gas analyzer using a quadrupole mass spectrometer. The results are shown in FIG.

As is clear from FIG. 3, when the raw material batch 1 was used, a remarkable foaming behavior was observed at 1300 to 1500 ° C., but when the raw material batch 2 was used, the foaming behavior was almost observed at 1300 ° C. or higher. There wasn't.
(Example 2)
Using two kinds of kaolin raw materials having different COD, changes in the bottom temperature and the dissolved amount of SO ₃ in the actual furnace were evaluated.

  First, raw material batches 1 and 2 were prepared in the same manner as in Example 1.

  Next, the raw material batch 1 was put into a continuous glass melting furnace of a burner heating type, and the glass was melted. The raw material batch 1 was switched to the raw material batch 2 5 days after the introduction.

Furthermore, the furnace bottom temperature during the melting period was measured by a thermocouple installed at the furnace bottom, and the dissolved amount of SO ₃ contained in the glass melt was measured by ion chromatography using SO ₃ in the collected glass. .

  The results are shown in FIGS.

4 and 5, it can be seen that when a batch having a high COD is used, the furnace bottom temperature increases and the dissolved amount of SO ₃ decreases. These facts indicate that the foam layer is less likely to be formed when the batch COD is increased.
(Example 3)
A high COD kaolin having a COD of 1450 ppm was used as an aluminum source, and raw material batches were prepared so as to have the compositions shown in Tables 2 and 3.

  Next, the obtained raw material batch was put into a burner heating type continuous melting furnace, and the glass was uniformly melted at 1500 to 1600 ° C. Subsequently, the molten glass was supplied to the bushing, and the molten glass was continuously drawn out in a filament form from the bushing nozzle. Various processing agents were applied to 2000 monofilaments drawn in this manner and converged to obtain glass fibers.

Although the kaolin raw material for glass manufacture of this invention is a raw material suitable for manufacture of glass fiber, it is not restricted to this. That is, if the glass is a glass in which a bubble layer is formed on the surface of the glass melt by the release of SO ₂ gas, the state of the bubble layer can be adjusted by using the kaolin raw material of the present invention.

BL1, BL2, BL3 Foam layer 1 Raw material batch 1
2 Raw material batch 2

Claims (7)

  A kaolin raw material for glass production characterized by having a chemical oxygen demand (COD) of 300 ppm or more.   The kaolin raw material for glass production according to claim 1, which is used for production of glass fibers.   A method for producing glass fibers, comprising melting a raw material batch prepared using the kaolin raw material for glass production according to claim 1 or 2, and forming the raw material batch into fibers.   The molten glass is supplied to the bushing, drawn continuously from the numerous bushing nozzles provided on the bottom surface of the bushing in the form of filaments, and then the processing agent is applied to the drawn monofilament and focused to form the molten glass in a fibrous form The method for producing a glass fiber according to claim 3, wherein the glass fiber is molded into a glass. SiO ₂ 42 to 67%, Al ₂ O ₃ 8 to 26%, and R ₂ O (wherein R is at least one of Li, Na and K) 0 to 2% by mass% based on oxide The manufacturing method of the glass fiber of Claim 3 or 4 which manufactures the glass fiber to contain. SiO ₂ 52 to 62%, Al ₂ O ₃ 10 to 16%, B ₂ O ₃ 0 to 8%, MgO 0 to 5%, CaO 16 to 25% and R ₂ O (provided by mass% based on oxide) , R represents, Li, at least one of Na and K) _{0 to 2%,} process for producing a glass fiber according to claim 3 or 4 for producing a glass fiber containing SO 3 0.01 to 1%.   The glass fiber manufacturing method according to any one of claims 3 to 6, wherein a glass fiber made of E glass is manufactured.