Composition for glass fiber

Abstract

A glass fiber composition with high elastic modulus and good productivity is provided. The glass fiber composition is characterized by containing 10 ppm or more of Cr2O3 by mass, and having an Al2O3 / Cr2O3 ratio greater than 150 by mass.

Description

Technical Field

[0001] This invention relates to compositions for glass fibers. Background Technology

[0002] Glass fiber (also known as glass fiber or glass filament) is generally manufactured by continuously forming (spinning) molten glass into fibers using a forming device called a perforator (also known as a platinum heating vessel) with a roughly rectangular shape. The perforator is positioned at the bottom of a pot-shaped vessel that serves as a temporary holding point for the molten glass. Furthermore, the perforator is constructed of a heat-resistant metal such as platinum and has multiple nozzle sections (or perforations) at its bottom. This perforator allows for temperature management, ensuring that the molten glass reaches an optimal temperature at the nozzle tips, achieving a high-temperature viscosity equivalent to 10... 3 The temperature is dPa·s (forming temperature Tx). Then, molten glass is continuously drawn out from the sprue nozzle and quenched, forming (spinning) into glass fibers.

[0003] During glass fiber forming, if the liquidus temperature Ty of the molten glass reaches or exceeds the forming temperature Tx, crystals that cause devitrification tend to precipitate in the molten glass near the nozzle of the sprue. This results in nozzle blockage, causing fiber breakage, also known as interruption. Therefore, it is preferable that the liquidus temperature Ty of the molten glass is lower than the forming temperature Tx (i.e., temperature difference ΔTxy = Tx - Ty > 0), and a larger temperature difference ΔTxy is even more preferable. However, if the forming temperature Tx is increased, although the temperature difference (ΔTxy) between it and the liquidus temperature Ty of the molten glass increases, the energy required for melting also increases, leading to increased costs or a shortened lifespan for equipment such as the sprue assembly. Therefore, it is preferable to decrease the forming temperature Tx.

[0004] Thus, while managing the forming temperature Tx and temperature difference ΔTxy is crucial in glass fiber manufacturing, the demand for highly functional glass fiber-containing composites and glass fibers with superior elastic modulus is increasing. Known glass types for glass fibers with these properties include S-glass (composed of SiO2, Al2O3, and MgO) and R-glass (composed of SiO2, Al2O3, MgO, and CaO). However, their forming temperature Tx and liquidus temperature Ty are both high, resulting in a small temperature difference ΔTxy, which poses a problem for productivity.

[0005] Therefore, Patent Document 1 discloses a glass fiber composition for improving the fiberization temperature (i.e., forming temperature Tx) and ΔT (i.e., temperature difference ΔTxy).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Publication No. 2009-514773 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] However, the glass fiber composition described in Patent Document 1 cannot be said to have both ensured a sufficiently low fiberization temperature and a sufficiently large ΔT, while also achieving a very high modulus of elasticity.

[0011] In view of the above, the objective of the present invention is to provide a glass fiber composition having a high elastic modulus and good productivity.

[0012] Problem-solving methods

[0013] The glass fiber composition of the present invention is characterized by containing 10 ppm or more of Cr2O3 by mass, and having an Al2O3 / Cr2O3 ratio greater than 150 by mass. Cr2O3 is an effective component for improving the elastic modulus, but if its content increases, the liquidus temperature Ty increases, resulting in a smaller temperature difference ΔTxy and reduced productivity. On the other hand, Al2O3 is also an effective component for improving the elastic modulus, but it also inhibits crystallization and phase separation in molten glass. Therefore, by limiting the Cr2O3 content and the Al2O3 / Cr2O3 ratio to the above-mentioned ranges, a glass composition that has both high elastic modulus and good productivity can be obtained. Furthermore, in the present invention, "x / y" means the value obtained by dividing the content of component x by the content of component y.

[0014] The glass fiber composition of the present invention preferably contains 10 to 6000 ppm of Cr2O3 by mass%.

[0015] Preferably, the glass fiber composition of the present invention has an MgO / Cr2O3 ratio of 20 or higher by mass. As described, Cr2O3 is an effective component for improving the elastic modulus. On the other hand, MgO is also an effective component for improving the elastic modulus, but at the same time, it also acts as a flux that facilitates the melting of glass raw materials. Therefore, by containing MgO, it has the effect of reducing the viscosity of the glass during melting, promoting bubble collapse, and lowering the forming temperature Tx. Therefore, by limiting the ratio of MgO to Cr2O3 to the above range, a glass composition that has a high elastic modulus while also lowering the forming temperature Tx can be obtained, resulting in good productivity.

[0016] Preferably, the glass fiber composition of the present invention contains 10 to 1000 ppm of P2O5 by mass, and the R2O / P2O5 ratio (R2O is the sum of Li2O, Na2O and K2O) is 0.01 or more by mass. This achieves a glass fiber composition that maintains both elastic modulus and good productivity.

[0017] Preferably, the glass fiber composition of the present invention contains less than 0.8% Na2O by mass. In this way, a glass fiber composition that can maintain both elastic modulus and good productivity can be achieved.

[0018] The glass fiber composition of the present invention preferably contains, by mass%, 25-70% SiO2, 13-25% Al2O3, 0.6-25% MgO, 3-15% CaO, and 0-less than 3% B2O3.

[0019] The glass fiber composition of the present invention preferably contains, by mass%, 10-6000 ppm Cr2O3, 50-70% SiO2, more than 15% and less than 20% Al2O3, 1.2-15% MgO, 3-15% CaO, more than 0% and less than 3% B2O3, more than 0.01% and less than 3% TiO2, and less than 0.8% Na2O.

[0020] Preferably, the glass fiber composition of the present invention has an Al2O3 / Cr2O3 ratio greater than 150 by mass.

[0021] Preferably, the glass fiber composition of the present invention has an MgO / Cr2O3 ratio of 20 or more by mass.

[0022] Preferably, the glass fiber composition of the present invention has an R2O / P2O5 ratio of 0.01 or higher by mass.

[0023] Preferably, the glass fiber composition of the present invention has a forming temperature Tx of 1400°C or lower. This allows for fiberization at low temperatures, thereby extending the lifespan of fiberization equipment such as stencils and reducing production costs.

[0024] Preferably, the glass fiber composition of the present invention has a temperature difference ΔTxy between the forming temperature Tx and the liquidus temperature Ty of 30°C or higher. This allows for good production efficiency of the glass fiber composition. Furthermore, the liquidus temperature Ty is obtained by placing glass powder that has passed through a standard 30-mesh sieve (500 μm aperture) and remained at a 50-mesh sieve (300 μm aperture) into a platinum boat, holding it in a temperature gradient furnace for 16 hours, and then measuring the temperature at which crystals (initial phase) precipitate.

[0025] Preferably, the glass fiber composition of the present invention has an elastic modulus E of 80 GPa or higher. This allows for the production of glass fiber-containing composite materials with low stress-induced strain and high physical strength.

[0026] The glass fiber of the present invention is characterized in that it contains any one of the above-mentioned glass fiber compositions.

[0027] The composite material containing glass fiber of the present invention is characterized in that it is a composite of the aforementioned glass fiber and a matrix material.

[0028] The effects of the invention

[0029] According to the present invention, it is possible to provide a composition for glass fiber that has a high elastic modulus and good productivity. Detailed Implementation

[0030] The glass fiber composition of the present invention is characterized in that it contains 10 ppm or more of Cr2O3 by mass%, and the Al2O3 / Cr2O3 ratio is greater than 150 by mass. The reasons for defining the glass composition in accordance with the above are explained below. Furthermore, in the following descriptions of the content of each component, unless otherwise specified, "%" means "mass percentage".

[0031] Cr2O3 is a component that increases the elastic modulus of glass without affecting its viscosity, thus effectively increasing the elastic modulus without changing the melting conditions. Furthermore, by increasing the elastic modulus (or specific elastic modulus) of the glass, the mechanical strength of glass fiber-containing composite materials can be improved. Therefore, the lower limit of Cr2O3 content is preferably 10 ppm or more, 20 ppm or more, 30 ppm or more, 31 ppm or more, 32 ppm or more, 33 ppm or more, 34 ppm or more, 35 ppm or more, and above 35 ppm, particularly preferably 36 ppm or more. On the other hand, if the content is too high, devitrification of the Cr2O3-Al2O3-MgO system will occur within the glass, reducing productivity. Therefore, the upper limit of Cr2O3 content is preferably below 10000ppm, 8000ppm, 6000ppm, 5000ppm, 4000ppm, 3000ppm, 2000ppm, 1000ppm, below 1000ppm, below 990ppm, below 980ppm, below 970ppm, below 960ppm, below 950ppm, below 940ppm, below 930ppm, below 920ppm, below 910ppm, below 900ppm, below 900ppm, below 850ppm, below 800ppm, below 750ppm, and particularly preferably below 700ppm.

[0032] To suppress deosmosis precipitation of the Cr2O3-Al2O3-MgO system, the ratio of Al2O3 to Cr2O3 becomes a crucial parameter. If this ratio is too low, deosmosis precipitation of the Cr2O3-Al2O3-MgO system tends to increase the liquidus temperature Ty and decrease the temperature difference ΔTxy. Consequently, the productivity of glass fibers decreases. Therefore, the lower limit of the Al2O3 / Cr2O3 ratio is preferably higher than 150, 155 or more, 160 or more, 165 or more, 170 or more, 175 or more, 180 or more, 185 or more, 190 or more, 195 or more, 196 or more, 197 or more, 198 or more, 199 or more, 200 or more, and particularly preferably higher than 200. Furthermore, if the Al2O3 / Cr2O3 ratio is too large, it is easier for the Cr2O3-Al2O3-MgO system to precipitate out and devitrify. Therefore, the upper limit is preferably below 10,000, below 8,000, below 6,000, and especially preferably below 5,000.

[0033] To suppress devitrification precipitation of the Cr2O3-Al2O3-MgO system, the ratio of MgO to Cr2O3 is just as important as the Al2O3 / Cr2O3 ratio. If the MgO / Cr2O3 ratio is too low, devitrification precipitation of the Cr2O3-Al2O3-MgO system tends to increase the liquidus temperature Ty and decrease the temperature difference ΔTxy. As a result, the productivity of glass fibers decreases. Therefore, the lower limit of MgO / Cr2O3 is preferably 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, above 80, 81 or more, 82 or more, 85 or more, 90 or more, 95 or more, 100 or more, above 100, 105 or more, 110 or more, 115 or more, 116 or more, 117 or more, 118 or more, 119 or more, 120 or more, and particularly preferably above 120. Furthermore, if the MgO / Cr2O3 ratio is too high, it is easier for the Cr2O3-Al2O3-MgO system to precipitate out and deorbit. Therefore, the upper limit is below 10000, below 8000, below 6000, below 5000, below 4000, below 3900, below 3800, below 3700, below 3600, below 3500, below 3400, below 3300, below 3200, below 3100, especially below 3000.

[0034] The following describes the components that may be contained in the glass fiber composition of the present invention.

[0035] Na₂O is a component that inhibits devitrification and precipitation in the Cr₂O₃-Al₂O₃-MgO system. Furthermore, it reduces the viscosity of molten glass, promotes bubble collapse, and lowers the forming temperature Tx during glass fiber forming. The lower limit of Na₂O content is preferably 0% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, 0.005% or more, 0.006% or more, 0.007% or more, 0.008% or more, 0.009% or more, or 0.01% or more, and particularly preferably above 0.01%. On the other hand, if the Na₂O content is too high, there is a tendency for the elastic modulus to decrease. Therefore, the upper limit of the Na2O content is preferably below 2%, below 2%, below 1.9%, below 1.8%, below 1.7%, below 1.6%, below 1.5%, below 1.4%, below 1.3%, below 1.2%, below 1.1%, below 1%, below 1%, below 0.9%, below 0.8%, below 0.8%, below 0.7%, below 0.7%, below 0.65%, below 0.6%, below 0.55%, and particularly preferably below 0.5%.

[0036] Li₂O is a component that inhibits devitrification and precipitation in the Cr₂O₃-Al₂O₃-MgO system. Furthermore, it reduces the viscosity of molten glass, promotes bubble collapse, and lowers the forming temperature Tx during glass fiber forming. However, because Li₂O is expensive, excessive Li₂O content increases production costs. Therefore, the upper limit of Li₂O content is preferably 2% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, and particularly preferably 0.5% or less. Conversely, the lower limit of Li₂O content is preferably 0% or more, and particularly preferably 0.0001% or more.

[0037] K₂O is a component that inhibits the devitrification and precipitation of Cr₂O₃-Al₂O₃-MgO systems. Furthermore, it reduces the viscosity of molten glass, promotes bubble collapse, and lowers the forming temperature Tx during glass fiber forming. The lower limit of K₂O content is preferably 0% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, 0.005% or more, 0.006% or more, 0.007% or more, 0.008% or more, 0.009% or more, or 0.01% or more, and particularly preferably higher than 0.01%. On the other hand, if the K₂O content is too high, the elastic modulus tends to decrease. Therefore, the upper limit of K2O content is preferably below 5%, below 5%, below 4.5%, below 4%, below 3.5%, below 3%, below 3%, below 2.9%, below 2.8%, below 2.7%, below 2.6%, below 2.5%, below 2.4%, below 2.3%, below 2.2%, below 2.1%, below 2%, below 2%, below 1.9%, below 1.8%, below 1.7%, below 1.6%, below 1.5%, and particularly preferably below 1.5%.

[0038] Furthermore, the lower limit of R2O content is 0% or more, but in order to suppress the devitrification precipitation of the Cr2O3-Al2O3-MgO system and to achieve the effect of reducing the viscosity of the glass during melting and promoting bubble rupture, thereby reducing the forming temperature Tx during glass fiber forming, the lower limit is preferably 0.001% or more, 0.005% or more, 0.01% or more, 0.02% or more, 0.03% or more, 0.04% or more, 0.05% or more, and particularly preferably higher than 0.05%. On the other hand, from the viewpoint of suppressing the decrease in the elastic modulus of glass, the upper limit of the R2O content is preferably 2% or less, less than 2%, less than 1.9%, less than 1.8%, less than 1.7%, less than 1.6%, less than 1.5%, less than 1.5%, less than 1.4%, less than 1.3%, less than 1.2%, less than 1.1%, less than 1%, less than 1%, less than 0.9%, less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.5%, less than 0.4%, less than 0.3%, and particularly preferably less than 0.2%. Here, R2O means the total amount of Li2O, Na2O, and K2O.

[0039] P2O5 can maintain Tx while suppressing the deosmosis precipitation of the Cr2O3-Al2O3-MgO system, thus effectively increasing the temperature difference ΔTxy. Furthermore, P2O5 is a non-volatile component, making its content during melting easy to adjust, thereby simplifying temperature control. The lower limit of P2O5 content is 1 ppm or more, 5 ppm or more, 10 ppm or more, 20 ppm or more, 30 ppm or more, 40 ppm or more, 50 ppm or more, 60 ppm or more, 70 ppm or more, 80 ppm or more, 90 ppm or more, 100 ppm or more, 110 ppm or more, 120 ppm or more, 130 ppm or more, 140 ppm or more, 150 ppm or more, 200 ppm or more, 250 ppm or more, 300 ppm or more, 350 ppm or more, 360 ppm or more, 370 ppm or more, 380 ppm or more, 390 ppm or more, 400 ppm or more, preferably above 400 ppm. On the other hand, if the P2O5 content is too high, the elastic modulus is likely to decrease. Therefore, the upper limit of the P2O5 content is preferably below 2000 ppm, below 1500 ppm, below 1400 ppm, below 1300 ppm, below 1200 ppm, below 1100 ppm, below 1050 ppm, and particularly preferably below 1000 ppm.

[0040] If the ratio of R2O to P2O5 (R2O / P2O5) is too low, the forming temperature Tx will increase, damage to the precious metal sprue will intensify, replacement frequency will increase, and production costs will rise. Therefore, the lower limit of R2O / P2O5 is preferably 0.01 or higher, 0.05 or higher, 0.1 or higher, 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1 or higher, higher than 1, 1.1 or higher, 1.2 or higher, 1.3 or higher, 1.4 or higher, 1.5 or higher, higher than 1.5, 1.6 or higher, 1.7 or higher, 1.8 or higher, 1.9 or higher, and particularly preferably 2 or higher. Furthermore, if R2O / P2O5 is too large, there is a tendency for the elastic modulus to decrease or ΔTxy to become smaller. Therefore, it is preferred to be below 2000, below 1000, below 200, below 100, below 50, below 20, and especially below 10.

[0041] SiO2 is the main component forming the glass framework. It also improves the mechanical strength and acid resistance of the glass. If the SiO2 content is too low, the elastic modulus tends to decrease. Therefore, the lower limit of the SiO2 content is preferably 25% or more, 30% or more, 40% or more, 45% or more, 50% or more, 50.5% or more, 51% or more, 51.5% or more, 52% or more, 52.5% or more, 53% or more, 53.5% or more, 54% or more, 54.5% or more, 55% or more, 55.5% or more, 56% or more, 56.5% or more, 57% or more, 57.5% or more, 58% or more, and particularly preferably higher than 58%. On the other hand, if the SiO2 content is too high, the viscosity of the molten glass will be too high, making it difficult to achieve a homogeneous molten state. As a result, adjusting the glass fiber diameter may become difficult. Furthermore, higher viscosity increases the energy required for glass melting, raises the forming temperature Tx, exacerbates damage to the precious metal sprue, increases replacement frequency, and raises production costs. Therefore, the upper limit of SiO2 content is preferably 70% or less, 69% or less, 68% or less, 67% or less, 66% or less, 65.5% or less, 65% or less, 64.5% or less, 64% or less, 63.5% or less, and 63% or less, particularly preferably less than 63%.

[0042] Al2O3 is a component that improves the chemical durability and mechanical strength of glass. It inhibits crystal precipitation and phase separation in molten glass, thereby increasing the elastic modulus of the glass. If the Al2O3 content is too low, the elastic modulus is prone to decrease. The lower limit of the Al2O3 content is preferably 13% or more, 13.5% or more, 14% or more, 14.5% or more, 15% or more, higher than 15%, 15.5% or more, 15.6% or more, 15.7% or more, 15.8% or more, 15.9% or more, 16% or more, 16.5% or more, 16.6% or more, 16.7% or more, 16.8% or more, 16.9% or more, 17% or more, higher than 17%, 17.1% or more, 17.2% or more, 17.3% or more, 17.4% or more, 17.5% or more, 17.6% or more, and particularly preferably 17.7% or more. On the other hand, if the Al2O3 content is too high, devitrifying crystals of mullite (3Al2O3·2SiO2), with Al2O3 as the main component, are easily formed in the molten glass. Furthermore, the viscosity of the molten glass is too high, making it difficult to achieve a homogeneous molten state. As a result, the dimensional accuracy of the glass fiber diameter tends to decrease. Additionally, the energy required for glass melting increases, the forming temperature Tx rises, damage to the precious metal sprue intensifies, replacement frequency increases, and production costs rise. Therefore, the upper limit of the Al2O3 content is preferably below 25%, below 25%, below 24.5%, below 23%, below 22.5%, below 22%, below 21.5%, below 21%, below 20.5%, below 20%, and particularly preferably below 20%.

[0043] MgO acts as a flux, facilitating the melting of glass raw materials. It reduces the viscosity of molten glass, promoting bubble collapse and lowering the forming temperature (Tx). Additionally, it increases the elastic modulus and specific modulus of glass. If the MgO content is too low, the viscosity of the molten glass is too high, making it difficult to achieve a homogeneous molten state. Consequently, the dimensional accuracy of the glass fiber diameter tends to decrease. Furthermore, an increase in the forming temperature (Tx) increases the energy required for glass melting, exacerbates damage to the precious metal sprue, increases replacement frequency, and raises production costs. Additionally, it tends to decrease the elastic modulus and specific modulus. Therefore, the lower limit of MgO content is preferably 0.6% or more, 1% or more, 1.2% or more, 1.5% or more, 2% or more, 2.5% or more, 3% or more, 3.5% or more, 4% or more, 4.5% or more, 5% or more, 5.5% or more, 6% or more, 6.5% or more, 7% or more, 7.5% or more, 8% or more, 8.5% or more, 9% or more, 9.5% or more, 10% or more, above 10%, 10.1% or more, 10.2% or more, 10.3% or more, 10.4% or more, 10.5% or more, 10.6% or more, 10.7% or more, 10.8% or more, 10.9% or more, 11% or more, and particularly preferably above 11%. On the other hand, if the MgO content is too high, in glass compositions with a high Al2O3 content, cordierite (2MgO·2Al2O3·5SiO2) devitrifying crystals are easily generated in the molten glass, which may become the cause of nozzle blockage in the glass fiber forming process. Therefore, the upper limit of MgO content is preferably 25% or less, 24% or less, 23% or less, 22% or less, 21% or less, 20% or less, 19.5% or less, 19% or less, 18.5% or less, 18% or less, 17.5% or less, 17% or less, 16.5% or less, 16% or less, 15.5% or less, 15% or less, 14.5% or less, 14% or less, 13.5% or less, 13.4% or less, 13.3% or less, 13.2% or less, 13.1% or less, below 13%, 12.9% or less, 12.8% or less, 12.7% or less, 12.6% or less, 12.5% ​​or less, 12.4% or less, 12.3% or less, 12.2% or less, and 12.1% or less, and particularly preferably 12% or less.

[0044] Like MgO, CaO acts as a flux, facilitating the melting of glass raw materials. It reduces the viscosity of molten glass, promoting bubble collapse and lowering the forming temperature (Tx) during glass fiber forming. If the CaO content is too low, the viscosity of the molten glass is too high, making it difficult to achieve a homogeneous molten state. Consequently, the dimensional accuracy of the glass fiber diameter tends to decrease. Furthermore, an increase in the forming temperature (Tx) increases the energy required for glass melting, exacerbating damage to the precious metal sprue, increasing replacement frequency, and raising production costs. Therefore, the lower limit of the CaO content is preferably 3% or higher, 3.5% or higher, 4% or higher, 4.5% or higher, 5% or higher, 5.5% or higher, 6% or higher, 6.5% or higher, 7% or higher, 7.1% or higher, 7.2% or higher, 7.3% or higher, 7.4% or higher, and particularly preferably 7.5% or higher. On the other hand, if the CaO content is too high, devitrifying crystals of wollastonite (CaO·SiO2) or diopside (2CaO·2Al2O3·5SiO2) are easily formed in the molten glass, which can cause nozzle blockage in the sprue during glass fiber forming. Furthermore, there is a tendency for the elastic modulus and specific elastic modulus to decrease. Therefore, the upper limit of the CaO content is preferably 15% or less, 14.5% or less, 14% or less, 13.5% or less, 13% or less, 12.9% or less, 12.8% or less, 12.7% or less, 12.6% or less, 12.5% ​​or less, 12.4% or less, 12.3% or less, 12.2% or less, 12.1% or less, and particularly preferably 12% or less.

[0045] If the MgO / CaO ratio is too low by mass, devitrifying crystals of wollastonite (CaO·SiO2) are easily formed in the molten glass, which can cause nozzle blockage during glass fiber forming. Furthermore, as the forming temperature Tx increases, the energy required for glass melting increases, exacerbating damage to precious metal-made cutters and increasing replacement frequency, tending to increase production costs. Therefore, the lower limit of MgO / CaO is preferably 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.8 or higher, 0.9 or higher, 1.0 or higher, 1.05 or higher, and particularly preferably 1.1 or higher. On the other hand, if the MgO / CaO ratio is too high, in glass compositions with high Al2O3 content, devitrifying crystals of cordierite (2MgO·2Al2O3·5SiO2) are easily formed in the molten glass, which can cause nozzle blockage during glass fiber forming. Furthermore, as the forming temperature Tx increases, the energy required for glass melting increases, leading to more severe damage to the precious metal sprue, more frequent replacements, and higher production costs. Therefore, the upper limit of MgO / CaO is preferably below 4, 3.5, 3, 2.5, 2.4, 2.3, 2.2, 2.1, 2, 1.9, 1.8, 1.7, and 1.65, and particularly preferably below 1.65.

[0046] Like SiO2, B2O3 is a component that forms the framework of glass network structures. It also reduces the viscosity of the glass, promoting bubble collapse, lowers the melting and forming temperatures (Tx), and increases the meltability of the glass. However, excessive B2O3 content leads to a decrease in the elastic modulus or increased evaporation of boron from the melt, which not only corrodes equipment but also pollutes the surrounding environment. The upper limit of the B2O3 content is preferably less than 3%, less than 2.9%, less than 2.8%, less than 2.7%, less than 2.6%, less than 2.5%, less than 2.4%, less than 2.3%, less than 2.2%, less than 2.1%, 2%, less than 1.9%, less than 1.8%, less than 1.7%, less than 1.6%, less than 1.5%, less than 1.4%, less than 1.3%, less than 1.2%, less than 1.1%, less than 1%, less than 0.9%, less than 0.8%, less than 0.75%, less than 0.7%, less than 0.65%, less than 0.6%, less than 0.55%, less than 0.5%, less than 0.5%, less than 0.45%, less than 0.45%, and particularly preferably less than 0.45%. On the other hand, the lower limit of the B2O3 content is preferably 0% or more, and particularly preferably 0.01% or more.

[0047] TiO2 is a component that increases the elastic modulus of glass. Furthermore, in the SiO2-Al2O3-MgO composition system, TiO2 lowers the devitrification precipitation temperature of mullite (3Al2O3·2SiO2) or cordierite (2MgO·2Al2O3·5SiO2). In addition, because it can lower the melting temperature and forming temperature Tx of the glass, as well as its viscosity, it can maintain both good productivity and the elastic modulus of the obtained glass. Therefore, the lower limit of TiO2 content is preferably 0% or more, 0.01% or more, 0.02% or more, 0.03% or more, 0.04% or more, 0.05% or more, 0.06% or more, 0.07% or more, 0.08% or more, 0.09% or more, 0.1% or more, 0.15% or more, 0.2% or more, 0.25% or more, 0.3% or more, 0.35% or more, 0.4% or more, 0.45% or more, 0.5% or more, 0.55% or more, 0.6% or more, 0.65% or more, 0.7% or more, 0.75% or more, 0.8% or more, higher than 0.8%, 0.85% or more, 0.9% or more, 0.95% or more, 1% or more, 1.05% or more, 1.10% or more, 1.15% or more, 1.2% or more, and particularly preferably higher than 1.2%. On the other hand, because TiO2 raw materials are expensive, excessive TiO2 content will increase production costs. Therefore, the upper limit of TiO2 content is preferably below 3%, below 2.9%, below 2.8%, below 2.7%, below 2.6%, below 2.5%, below 2.4%, below 2.3%, below 2.2%, below 2.1%, below 2%, below 1.9%, below 1.8%, below 1.7%, and particularly preferably below 1.7%.

[0048] In addition to the above-mentioned components, the glass fiber composition of the present invention may also contain the following components.

[0049] SrO and BaO are components that reduce viscosity at high temperatures. However, if the content of SrO and / or BaO is too high, the phase separation property of the molten glass is likely to increase. The upper limit of SrO content is preferably 2% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, and particularly preferably 0.5% or less. On the other hand, the lower limit of SrO content is preferably 0% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, 0.005% or more, 0.006% or more, 0.007% or more, 0.008% or more, 0.009% or more, 0.01% or more, and particularly preferably 0.05% or more. The upper limit of BaO content is preferably 2% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1.0% or less, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, and particularly preferably 0.5% or less. On the other hand, the lower limit of BaO content is preferably 0% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, and particularly preferably 0.005% or more.

[0050] If R'O is too low, the viscosity of the molten glass increases, the forming temperature Tx rises, the energy required for glass melting increases, damage to the precious metal sprue intensifies, replacement frequency increases, and production costs rise. Furthermore, the elastic modulus of the glass tends to decrease. Therefore, the lower limit of R'O is preferably 5% or more, 6% or more, 7% or more, 8% or more, 9% or more, 10% or more, 11% or more, 12% or more, 13% or more, 14% or more, and particularly preferably 15% or more. On the other hand, if R'O is too high, devitrifying crystals such as cordierite (2MgO·2Al2O3·5SiO2) and wollastonite (CaO·SiO2) are prone to form in the molten glass, potentially causing nozzle blockage during glass fiber forming. Therefore, the upper limit of R'O is 40% or less, 39% or less, 38% or less, 37% or less, 36% or less, 35% or less, 34% or less, 33% or less, 32% or less, 31% or less, preferably 30% or less. Here, R'O is the total amount of MgO, CaO, SrO and BaO.

[0051] Like TiO2, ZrO2 is a component that increases the elastic modulus of glass. The lower limit of ZrO2 content is preferably 0% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, and particularly preferably 0.005% or more. On the other hand, if the ZrO2 content is too high, in glass melts with the SiO2-Al2O3-MgO composition system, the devitrification precipitation temperature of mullite (3Al2O3·2SiO2) or cordierite (2MgO·2Al2O3·5SiO2) may increase. Therefore, the upper limit of the ZrO2 content is preferably 10% or less, 9.5% or less, 9% or less, 8.5% or less, 8% or less, 7.5% or less, 7% or less, 6.5% or less, 6% or less, 5.9% or less, 5.8% or less, 5.7% or less, 5.6% or less, 5.5% or less, 5.4% or less, 5.3% or less, 5.2% or less, 5.1% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, 0.5% or less, and particularly preferably 0.1% or less.

[0052] Like ZrO2 and TiO2, Fe2O3 is a component that increases the elastic modulus of glass. The lower limits for Fe2O3 content are 0% or more, 0.01% or more, 0.02% or more, 0.03% or more, 0.04% or more, 0.05% or more, 0.06% or more, 0.07% or more, 0.08% or more, 0.09% or more, 0.1% or more, 0.15% or more, 0.2% or more, and preferably 0.25% or more. On the other hand, if the Fe2O3 content is too high, Fe2O3-based devitrifying crystals can easily form in the molten glass, potentially causing nozzle blockage during glass fiber forming. The upper limit of the Fe2O3 content is preferably below 3%, below 2.9%, below 2.8%, below 2.7%, below 2.6%, below 2.5%, below 2.4%, below 2.3%, below 2.2%, below 2.1%, below 2%, below 1.9%, below 1.8%, below 1.7%, below 1.6%, and particularly preferably below 1.5%.

[0053] Y2O3 is a component that increases the elastic modulus of glass, but if the content of Y2O3 is too high, the density will increase. Therefore, the content of Y2O3 is preferably less than 2%, less than 1.5%, less than 1%, less than 1%, less than 0.5%, less than 0.5%, less than 0.1%, and particularly preferably less than 0.1%.

[0054] Additionally, for the purpose of improving clarity, it may contain any one or more of SnO2, As2O3, Sb2O3, F2, CeO2, SO3, and Cl2. The content of each is preferably 0–2%, 0–1%, and particularly preferably 0–0.8%.

[0055] To improve melt properties, elastic modulus, alkali resistance, acid resistance, water resistance, molding temperature, and liquidus temperature, in addition to the above-mentioned components, ZnO, MnO, La2O3, WO3, Nb2O5, etc., may be added in appropriate amounts as needed, up to 2% of each.

[0056] In addition, the content of each of the following elements is limited to up to 0.5%: H2, O2, CO2, CO, H2O, He, Ne, Ar, and N2. Furthermore, the glass may contain precious metals such as Pt, Rh, and Au up to 500 ppm.

[0057] Furthermore, preferred compositions for glass fiber applications include those containing, by mass percent, 10–6000 ppm Cr₂O₃, 50–70% SiO₂, 15–20% Al₂O₃, 1.2–15% MgO, 3–15% CaO, 0–less than 3% B₂O₃, 0.01–less than 3% TiO₂, and less than 0.8% Na₂O. In this composition, the Al₂O₃ / Cr₂O₃ ratio is preferably greater than 150 by mass. Additionally, the MgO / Cr₂O₃ ratio is preferably 100 or more by mass. Furthermore, the R₂O / P₂O₅ ratio is preferably 0.01 or more by mass.

[0058] Next, the characteristics of the glass fiber composition of the present invention will be described.

[0059] The glass fiber composition of the present invention preferably has a forming temperature Tx of 1400°C or below, 1390°C or below, 1385°C or below, 1380°C or below, 1375°C or below, 1370°C or below, 1369°C or below, 1368°C or below, 1367°C or below, and 1366°C or below, particularly preferably 1365°C or below. If the forming temperature Tx is too high, the energy required for melting the glass increases, damage to the precious metal stencil intensifies, replacement frequency increases, and production costs rise. Furthermore, while there is no particular limitation on the lower limit of the forming temperature Tx, it is practically above 1100°C.

[0060] The glass fiber composition of the present invention preferably has a liquid phase temperature Ty of 1300°C or lower, 1290°C or lower, 1285°C or lower, 1280°C or lower, 1279°C or lower, 1278°C or lower, 1277°C or lower, 1276°C or lower, 1275°C or lower, 1274°C or lower, 1273°C or lower, 1272°C or lower, 1271°C or lower, 1270°C or lower, 1269°C or lower, 1268°C or lower, 1267°C or lower, 1266°C or lower, and particularly preferably 1265°C or lower. If the liquid phase temperature Ty is too high, the temperature difference ΔTxy tends to decrease, thus tending to deteriorate productivity. Furthermore, the lower limit of the liquid phase temperature Ty is not particularly limited, but in practice it is above 1000°C.

[0061] The glass fiber composition of the present invention preferably has a temperature difference ΔTxy between the forming temperature Tx and the liquidus temperature Ty of 30°C or higher, 40°C or higher, 45°C or higher, 50°C or higher, 55°C or higher, 60°C or higher, 65°C or higher, 70°C or higher, 75°C or higher, 80°C or higher, 85°C or higher, and particularly preferably higher than 85°C. If the temperature difference ΔTxy is too small, devitrification is prone to occur during glass fiber forming, causing nozzle blockage in the stencil and thus reducing productivity. Furthermore, while there is no particular upper limit to the temperature difference ΔTxy, it is practically below 180°C.

[0062] The glass fiber composition of the present invention preferably has an elastic modulus E of 80 GPa or higher, 81 GPa or higher, 82 GPa or higher, 83 GPa or higher, 84 GPa or higher, 85 GPa or higher, 86 GPa or higher, 87 GPa or higher, 88 GPa or higher, 89 GPa or higher, 90 GPa or higher, 91 GPa or higher, 92 GPa or higher, and particularly preferably 93 GPa or higher. If the elastic modulus E is too low, it is difficult to achieve high functionality (specifically, improved mechanical strength) in the composite material containing glass fiber. Furthermore, while there is no particular upper limit to the elastic modulus E, it is practically 150 GPa or lower.

[0063] The glass fiber composition of the present invention preferably has a lower limit of density ρ of 2 g / cm³. 3 Above, 2.1 g / cm 3 Above, 2.2g / cm 3 Above, 2.3g / cm 3 Above, 2.4 g / cm 3 Above, 2.5g / cm 3 Above, 2.55g / cm 3 The above, especially preferred, is 2.6 g / cm³. 3The above is true. If the density ρ is too low, the elastic modulus E tends to decrease. On the other hand, if the density ρ is too high, it is difficult to achieve high functionality (specifically, lightweight) in composite materials containing glass fibers. Therefore, the upper limit of density ρ is preferably 3 g / cm³. 3 Below, 2.9g / cm 3 Below, 2.8g / cm 3 The following is particularly preferred: 2.7 g / cm³ 3 the following.

[0064] The glass fiber composition of the present invention preferably has a specific elastic modulus calculated as elastic modulus E / density ρ of 33 or more, 33.5 or more, 34 or more, 34.5 or more, 35 or more, 35.5 or more, and particularly preferably 36 or more. On the other hand, if the specific elastic modulus is too low, it is difficult to achieve high functionality of the glass fiber-containing composite material (specifically, to achieve both lightweighting and improved mechanical strength). Furthermore, while there is no particular upper limit for the specific elastic modulus, it is practically 45 or less.

[0065] In order to reduce the viscosity of the melt of the glass fiber composition of the present invention and promote clarification, it is preferable that the water content (β-OH) in the glass fiber composition is 0.001 mm. －1 Above, 0.005mm －1 Above, 0.01mm －1 Above, 0.015mm －1 Above, 0.02mm －1 Above, 0.025mm －1 The above is particularly preferred, with 0.03mm being the optimal size. －1 That's all. On the other hand, if the β-OH content of the water is too high, the generation of bubbles caused by clarification in the glass melt increases, making it easier for glass fibers to be cut, and tending to reduce productivity. Therefore, the upper limit of the β-OH content is preferably 1 mm. －1 Below, 0.95mm －1 Below, 0.90mm －1 Below, 0.85mm －1 Below, 0.8mm －1 Below, 0.75mm －1 Below, 0.7mm －1 Below, 0.65mm －1 Below, 0.6mm －1 The following is particularly preferred: 0.55mm －1 the following.

[0066] Next, the glass fiber and the composite material containing the glass fiber of the present invention will be described.

[0067] The glass fiber of the present invention, in which the glass is composed of the glass fiber composition described above, preferably contains 95% or more of the solid content. If the glass fiber of the present invention is composed of 95% or more of the glass fiber composition described above, with the remainder being organic matter such as coatings, then the surface of the glass fiber is less prone to damage during various processing steps such as the weaving process, and stable strength properties can be maintained. Furthermore, the glass fiber can fully exert various physicochemical properties. The content of the glass fiber composition of the glass fiber of the present invention, in terms of solid content, is 95-100% by mass, preferably 95.5% to less than 100% by mass, 96% to 99.99% by mass, and particularly preferably 96.5% to less than 99.99% by mass. Here, the solid content is calculated by measuring the mass of the glass fiber after drying the moisture content on the surface of the glass fiber to less than 0.1% by mass, and then heating it at high temperature to remove the organic matter coated on the surface of the glass fiber, and only measuring the mass of the glass.

[0068] Furthermore, when the composition for glass fibers, expressed as solids, is less than 95% by mass, the protective performance of the organic matter coated on the surface of the glass fibers will not be significantly improved. In addition, the amount of organic matter required for coating increases, thus increasing manufacturing costs and making it uneconomical. On the other hand, if the composition for glass fibers, expressed as solids by mass, is greater than 99.99% by mass, the protective performance of the glass fiber surface may not be fully realized.

[0069] Furthermore, the glass fiber of the present invention, as the shape of the fiber cross section perpendicular to the pulling direction during spinning, can be an irregular cross section shape such as ellipse, trefoil, flat shape, rectangle, drum shape, and polygon, in addition to a circle.

[0070] Furthermore, the glass fiber of the present invention is preferably in the form of chopped strands, glass fiber yarn, or untwisted roving. If so, it can be used for a variety of applications.

[0071] Here, chopped strands are fibers cut into regular lengths from a glass fiber bundle, glass fiber yarn is made by twisting continuous glass fibers, and untwisted roving is made by arranging multiple strands of glass fiber bundle as filaments.

[0072] Regarding chopped filaments, there are no limitations on fiber length and diameter; suitable options can be selected based on the application. Furthermore, any method can be used to manufacture chopped filaments. One method involves spinning molten glass and directly cutting the resulting glass filaments to obtain short fibers. Alternatively, molten glass can be spun, the resulting glass filaments can be wound into a long fiber cake, and then the filaments can be drawn from the cake while being cut using a cutting device. In this case, any cutting method can be used. For example, an external cutting device, an internal cutting device, or a hammer mill can be used. The resulting chopped filaments can be randomly stacked on a plane and bonded with an adhesive to form a felt-like structure, or they can be three-dimensionally randomly stacked. Alternatively, they can be glass masterbatch (GMB) granules containing a high proportion of glass fibers, or granular LFTP (long fiber reinforced thermoplastic resin) containing glass fibers oriented in the same direction.

[0073] Regarding fiberglass yarn, as long as a specified twist is applied, including untwisted fiberglass yarn, there are no special restrictions on the magnitude and direction of its twist.

[0074] In addition, regarding untwisted roving, as long as multiple strands of the original fiber bundle are arranged into a bundle and wound into a cylindrical shape, there is no problem with the appearance, and there are no restrictions on the diameter of the wound fiber or the number of strands arranged.

[0075] In addition to the above, the glass fiber of the present invention can also be used in the form of continuous filament mat, adhesive mat, fabric, tape, woven fabric, or shredded fiber. It can also be used as a prepreg for impregnation with resin. Furthermore, regarding the application and forming methods of the glass fiber, it can be used in spraying, hand lay-up, fiber winding, injection molding, centrifugal molding, roll forming, or BMC and SMC methods using matching molds, etc.

[0076] Furthermore, the glass fibers of the present invention can be coated with various surface treatment agents to impart desired properties. For example, one or more of the following agents, in any combination, such as bundlers, binders, coupling agents, lubricants, antistatic agents, emulsifiers, emulsion stabilizers, pH adjusters, defoamers, colorants, antioxidants, mildew inhibitors, or stabilizers, can be applied to the surface of the glass fibers in appropriate amounts to coat them. Moreover, such surface treatment agents or coating agents can be starch-based or plastic-based. For example, if the bundler is for FRP, acrylic, epoxy, urethane, polyester, vinyl acetate, vinyl acetate-ethylene copolymer, etc., can be suitable.

[0077] The composite material containing the glass fiber of the present invention is a composite of the aforementioned glass fiber and a matrix material. Both organic and inorganic matrix materials can be used as the matrix material.

[0078] Organic matrix materials are represented by organic resins such as thermoplastic resins and thermosetting resins. Depending on the application, the most suitable and optimal resin can be used alone or in combination.

[0079] Examples of the aforementioned thermoplastic resins include acrylic resins, polyacetal resins, polyamide resins, polyethylene resins, polyethylene terephthalate resins, polycarbonate resins, polystyrene resins, polyphenylene sulfide resins, polybutylene terephthalate resins, polypropylene resins, and polyvinyl chloride resins.

[0080] Examples of the aforementioned thermosetting resins include epoxy resins, thermosetting modified polyphenylene ether resins, thermosetting polyimide resins, urea resins, acrylic resins, silicone resins, benzoxazine resins, phenolic resins, unsaturated polyester resins, bismaleimide triazine resins, alkyd resins, furan resins, melamine resins, polyurethane resins, and aniline resins.

[0081] Examples of inorganic matrix materials include concrete and mortar. Concrete is made by mixing cement with sand, gravel, and water, while mortar is made by mixing cement with sand and water. There are no particular restrictions on the mixing ratios of the various components in concrete and mortar, or on the type of cement used. Ash, etc., may also be added.

[0082] In addition to glass fiber, composite materials containing glass fiber may also contain other structural reinforcing materials, such as carbon fiber, ceramic fiber, or beads.

[0083] The glass fiber of the present invention can be used alone. For example, in a liquid crystal display device used as a display device for a liquid crystal television or personal computer, the glass fiber is suitable as a liquid crystal spacer for maintaining the gap between two substrate glass sheets because the fiber diameter has stable dimensional accuracy.

[0084] Furthermore, the glass fiber composition and glass fiber of the present invention can be reused. That is, articles containing the glass fiber composition and glass fiber of the present invention can be remelted into fibrous shapes, or various non-fiber shapes such as spheres and granules, and used for other purposes. For example, they can also be used as soil additives, concrete additives or aggregates, asphalt additives, etc.

[0085] Next, the method for manufacturing the glass fiber of the present invention will be described.

[0086] First, the batch of glass raw materials, prepared according to the above composition (and properties), is fed into a glass melting furnace to vitrify, melt, and homogenize it. The composition has already been described and will not be explained here.

[0087] Next, the molten glass is spun into glass fibers. More specifically, the molten glass is fed to a spinneret. The molten glass fed to the spinneret is continuously drawn out in fine filaments from multiple nozzles located on its bottom surface. Various treatment agents are applied to these drawn filaments, and they are bundled together after reaching a predetermined number, thereby obtaining glass fibers.

[0088] The glass fibers of the present invention thus formed are processed into chopped filaments, glass fiber yarns, untwisted rovings, etc., for various applications.

[0089] Example

[0090] The present invention will now be described in detail based on embodiments. Furthermore, the following embodiments are merely illustrative, and the present invention is not limited to any of the embodiments described below.

[0091] (Composition for glass fiber)

[0092] Tables 1 to 9 show examples (samples No. 1 to 38, 40 to 60) and comparative examples (sample No. 39) of the glass fiber compositions of the present invention.

[0093] Table 1

[0094]

[0095] Table 2

[0096]

[0097] Table 3

[0098]

[0099] Table 4

[0100]

[0101] Table 5

[0102]

[0103] Table 6

[0104]

[0105] Table 7

[0106]

[0107] Table 8

[0108]

[0109] Table 9

[0110]

[0111] Each sample was prepared as follows.

[0112] First, according to the glass composition in the table, various natural and / or chemically synthesized raw materials are weighed and mixed in specified quantities to prepare a raw material batch. Second, this raw material batch is placed in a platinum-rhodium crucible and heated to 1550°C for 5 hours in an atmospheric atmosphere. Furthermore, to obtain homogeneous molten glass, a heat-resistant stirring rod is used to stir the molten glass during the heating and melting process.

[0113] Subsequently, the homogeneous molten glass is poured into a carbon mold and cast into a specified shape. After annealing, the final glass sample for measurement is obtained.

[0114] The physical properties of the obtained glass samples were measured using the following methods.

[0115] Forming temperature Tx (equivalent to a molten glass viscosity of 10) 3 The viscosity (dPa·s at temperature) was measured as follows: First, the glass sample was placed in an alumina crucible and heated to a molten state. Viscosity data at various temperatures were measured using the platinum ball pulling method, and viscosity curves were plotted accordingly. From the obtained viscosity curves, the viscosity equivalent to molten glass of 10 was calculated using interpolation. 3 The temperature in dPa·s is used as the forming temperature Tx.

[0116] The liquidus temperature Ty was measured as follows: Glass powder that passed through a standard 30-mesh (300 μm) sieve but remained on a 50-mesh (300 μm) sieve was packed into a platinum container with an appropriate bulk density. The container was then placed in an indirect-heating temperature gradient furnace with the maximum temperature set at 1320 °C and allowed to stand for 16 hours in an atmospheric atmosphere. After the glass sample cooled to room temperature, it was observed using a polarizing microscope. Based on the temperature gradient within the indirect-heating furnace, the temperature corresponding to the point where crystals (primary phase) began to precipitate was calculated and taken as the liquidus temperature Ty.

[0117] The temperature difference ΔTxy between the forming temperature Tx and the liquid phase temperature Ty is calculated by subtracting (liquid phase temperature Ty) from (forming temperature Tx).

[0118] The elastic modulus E was obtained by annealing a 40mm×20mm×2mm plate-shaped sample that had been ground with a grinding slurry containing 1200 alumina powder in a conventional annealing furnace, and then measuring the elastic modulus of both surfaces at room temperature using a free resonance type elastic modulus measuring device (manufactured by Techno Plus Co., Ltd., Japan).

[0119] The density ρ was measured using the known Archimedes method with a sample annealed in a conventional annealing furnace.

[0120] The specific elastic modulus is calculated by (elastic modulus E) / (density ρ).

[0121] As shown in Tables 1-9, the elastic modulus E of samples No. 1-38 and 40-60, which served as examples, was 90.1 GPa or higher, and the temperature difference ΔTxy was 27°C or higher. Furthermore, the effects of Cr2O3 and Al2O3 on the elastic modulus E and temperature difference ΔTxy can be examined as follows. For example, comparing samples No. 34 and 36, it can be seen that the elastic modulus E increases with increasing Cr2O3 content. On the other hand, the temperature difference ΔTxy decreases because the liquidus temperature Ty increases due to the decrease in Al2O3 / Cr2O3 ratio. Thus, it can be seen that by appropriately adjusting the Cr2O3 content and the Al2O3 / Cr2O3 ratio, a high elastic modulus E can be achieved while maintaining the temperature difference ΔTxy.

[0122] On the other hand, in comparative example No. 39, the Al2O3 / Cr2O3 ratio was as low as 150, resulting in deosmosis precipitation of the Cr2O3-Al2O3-MgO system. As a result, the temperature difference ΔTxy was as low as -11℃.

[0123] (Glass fiber and composite materials containing glass fiber)

[0124] After melting the glass fiber composition having the composition of Sample No. 1 of Example 1, glass monofilaments with a diameter of 3 μm can be continuously formed using a stencil apparatus with a platinum nozzle. Even with such continuous forming, breakage is unlikely to occur, thus glass monofilaments with stable fiber diameters can be obtained.

[0125] Next, a suitable amount of a binding agent containing a silane coupling agent is applied to the surface of the multiple glass monofilaments formed using the aforementioned stencil apparatus by impregnation, and then air-dried to obtain glass fibers (glass precursors). Multiple glass fibers are bundled together, impregnated in an organic solvent composed of polypropylene resin for curing, and then cut to the desired length to obtain granular LFTPs with glass fibers oriented in the same direction.

[0126] By using the LFTP obtained in this way, the length of glass fibers in glass fiber-containing composite materials can be extended, thus obtaining composite materials containing high-strength glass fibers. For example, it can improve flexural strength in sheet-like materials.

[0127] Industrial availability

[0128] Glass fibers and composite materials containing glass fibers made using the glass fiber composition of the present invention are expected to be used in a variety of applications. For example, in aircraft-related applications, they can be used in aircraft substrates, interior materials, vibration damping materials, etc.; in automotive-related applications, they can be used in vibration damping reinforcement materials, bumpers, engine underbody panels, fenders, roof panels, vehicle bodies, spoilers, muffler filters, dashboards, water tanks, timing belts, etc. In addition, in marine-related applications, they can be used in substrates for motorboats, yachts, fishing boats, etc.; in building, civil engineering, and building materials-related applications, they can be used in decorative walls, skylights / light covers, surface-mounted fabrics, insect nets, roller blinds, tent membranes, backlit signs, corrugated, flat, and folded panels for lighting, concrete anti-corrosion and reinforcement materials, exterior wall reinforcement materials, waterproof coating materials, smoke curtains, non-combustible transparent partitions, projection films, road reinforcement materials, bathtubs, and integrated bathrooms, etc.; in leisure and sports-related applications, they can be used in fishing rods, tennis rackets, golf clubs, skis, helmets, etc. In addition, in electronic equipment applications, it can be used in printed circuit boards, insulating boards, terminal boards, IC substrates, electronic equipment housing materials, electronic component packaging materials, optical equipment housing materials, optical component packaging materials, and insulating supports. In industrial applications, it can be used in windmill blades, glass filter bags, outer materials for non-combustible insulation materials, reinforcing materials for resin grinding wheels, and aluminum foil filters. In agricultural applications, it can be used in plastic greenhouses, agricultural poles, and silos.

Claims

1. A composition for glass fiber, characterized in that, It contains more than 10 ppm of Cr2O3 by mass, and the Al2O3 / Cr2O3 ratio is greater than 150 by mass.

2. The composition for glass fiber according to claim 1, characterized in that, It contains 10ppm to 6000ppm of Cr2O3 by mass%.

3. The composition for glass fiber according to claim 1 or 2, characterized in that, The MgO / Cr2O3 ratio is above 20 by mass.

4. The composition for glass fiber according to claim 1 or 2, characterized in that, It contains 10ppm to 1000ppm of P2O5 by mass, and the R2O / P2O5 ratio is 0.01 or more by mass, wherein R2O is the sum of Li2O, Na2O and K2O.

5. The composition for glass fiber according to claim 4, characterized in that, It contains less than 0.8% Na2O by mass.

6. The composition for glass fiber according to claim 1 or 2, characterized in that, By mass%, it contains 25%–70% SiO2, 13%–25% Al2O3, 0.6%–25% MgO, 3%–15% CaO, and more than 0% but less than 3% B2O3.

7. A composition for glass fiber, characterized in that, By mass%, it contains Cr2O3 10 ppm to 6000 ppm, SiO2 50% to 70%, Al2O3 more than 15% and less than 20%, MgO 1.2% to 15%, CaO 3% to 15%, B2O3 more than 0% and less than 3%, TiO2 more than 0.01% and less than 3%, and Na2O less than 0.8%.

8. The composition for glass fiber according to claim 7, characterized in that, The Al2O3 / Cr2O3 ratio is greater than 150 by mass.

9. The composition for glass fiber according to claim 7 or 8, characterized in that, The MgO / Cr2O3 ratio is above 20 by mass.

10. The composition for glass fiber according to claim 7 or 8, characterized in that, The R2O / P2O5 ratio is greater than 0.01 by mass.

11. The composition for glass fiber according to claim 1 or 2, characterized in that, The forming temperature Tx of the glass fiber composition is below 1400°C.

12. The composition for glass fiber according to claim 1 or 2, characterized in that, The temperature difference ΔTxy between the forming temperature Tx and the liquid phase temperature Ty of the glass fiber composition is 30°C or higher.

13. The composition for glass fiber according to claim 1 or 2, characterized in that, The elastic modulus E of the glass fiber composition is 80 GPa or higher.

14. A type of glass fiber, characterized in that, A composition for glass fiber as described in claim 1 or 2.

15. A composite material containing glass fiber, characterized in that, It is the composite of glass fiber and matrix material as described in claim 14.

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