Glass fiber composition

Abstract

To provide a glass fiber composition having a high modulus of elasticity and superior productivity.SOLUTION: A glass fiber composition contains Cr2O3 in an amount of 10 ppm or more in mass%, where the mass ratio Al2O3 / Cr2O3 exceeds 150.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composition for glass fibers.

Background Art

[0002] Glass fibers (also referred to as glass fibers or glass filaments) are generally manufactured by continuously forming (spinning) molten glass into a fibrous shape using a forming device called a bushing device (also referred to as a platinum heating container) having a generally substantially rectangular appearance. The bushing device is disposed at the bottom of a pot-shaped container having a function of temporarily retaining molten glass. The bushing device is made of a heat-resistant metal material such as platinum, and has a number of nozzle portions (or orifice portions) at its bottom. By this bushing device, temperature control is performed so that the molten glass reaches an optimum temperature at the tip of the bushing nozzle, that is, a temperature (forming temperature Tx) corresponding to a high-temperature viscosity of 10 3 dPa·s. Then, the molten glass is continuously drawn out from the bushing nozzle and rapidly cooled to form (spin) into glass fibers.

[0003] When forming glass fibers, if the liquidus temperature Ty of the molten glass is equal to or higher than the forming temperature Tx of the glass, crystals that cause devitrification are likely to precipitate in the molten glass in the vicinity of the bushing nozzle. As a result, the bushing nozzle becomes clogged, causing a thread break, also called a break. For this reason, it is preferable that the liquidus temperature Ty of the molten glass is lower than the forming temperature Tx (that is, the temperature difference ΔTxy = Tx - Ty> 0), and it is more preferable that the temperature difference ΔTxy is larger. However, when the forming temperature Tx is increased, the temperature difference (ΔTxy) from the liquidus temperature Ty of the molten glass increases. In this case, however, with an increase in the energy required for melting, problems such as an increase in manufacturing cost and a shortening of the life of auxiliary equipment such as the bushing device occur. Therefore, it is preferable to lower the forming temperature Tx.

[0004] Thus, in the production of glass fibers, it is very important to control the forming temperature Tx and the temperature difference ΔTxy. On the other hand, the high functionality of glass fiber-containing composite materials is required, and the demand for glass fibers with better elastic modulus is increasing. As glass for such glass fibers, S glass composed of a glass composition of SiO2, Al2O3, and MgO, and R glass composed of a glass composition of SiO2, Al2O3, MgO, and CaO are known. However, since these have a high forming temperature Tx and a high liquidus temperature Ty, the temperature difference ΔTxy is small, resulting in problems with productivity.

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

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0007] However, it cannot be said that the glass fiber composition described in Patent Document 1 achieves a sufficiently high elastic modulus while ensuring a sufficiently low fiberization temperature and a sufficiently large ΔT.

[0008] In view of the above, an object of the present invention is to provide a glass fiber composition having a high elastic modulus and good productivity.

Means for Solving the Problems

[0009] The glass fiber composition of the present invention contains Cr₂O₃ in an amount of 10 ppm or more by mass%, and the mass ratio of Al₂O₃ / Cr₂O₃ is more than 150. Cr₂O₃ is a component effective for improving the elastic modulus. However, when its content increases, the liquidus temperature Ty becomes high, and as a result, the temperature difference ΔTxy becomes small and the productivity decreases. On the other hand, Al₂O₃ is also a component effective for improving the elastic modulus, but it is a component that suppresses the crystallization of crystals and the formation of phase separation in molten glass. Therefore, by regulating the content of Cr₂O₃ and the ratio of Al₂O₃ to Cr₂O₃ within the above ranges, it is possible to obtain a glass composition having a high elastic modulus and good productivity. In the present invention, "x / y" means the value obtained by dividing the content of the x component by the content of the y component.

[0010] The glass fiber composition of the present invention preferably contains Cr₂O₃ in an amount of 10 to 6000 ppm by mass%.

[0011] The glass fiber composition of the present invention preferably has a mass ratio of MgO / Cr₂O₃ of 20 or more. As described, Cr₂O₃ is a component effective for improving the elastic modulus. On the other hand, MgO is also a component effective for improving the elastic modulus, and at the same time, it is also a component having a function as a flux that facilitates melting of the glass raw materials. Therefore, by containing MgO, it has the function of reducing the viscosity during glass melting, promoting defoaming, and lowering the forming temperature Tx. Therefore, by regulating the ratio of MgO to Cr₂O₃ within the above ranges, it is possible to obtain a glass composition having a high elastic modulus while lowering the forming temperature Tx and having good productivity.

[0012] The glass fiber composition of the present invention preferably contains P₂O₅ in an amount of 10 to 1000 ppm by mass%, and the mass ratio of R₂O / P₂O₅ (where R₂O is the total amount of Li₂O, Na₂O, and K₂O) is 0.01 or more. By doing so, it is possible to obtain a glass fiber composition having good productivity while maintaining the elastic modulus.

[0013] The glass fiber composition of the present invention preferably contains less than 0.8% of Na2O by mass%. By doing so, it is possible to obtain a glass fiber composition that has good productivity while maintaining the elastic modulus.

[0014] The glass fiber composition of the present invention preferably contains, by mass%, 25 to 70% of SiO2, 13 to 25% of Al2O3, 0.6 to 25% of MgO, 3 to 15% of CaO, and less than 3% of B2O3.

[0015] The glass fiber composition of the present invention preferably contains, by mass%, 10 to 6000 ppm of Cr2O3, 50 to 70% of SiO2, more than 15% to 20% of Al2O3, 1.2 to 15% of MgO, 3 to 15% of CaO, less than 3% of B2O3, less than 0.01 to 3% of TiO2, and less than 0.8% of Na2O.

[0016] The glass fiber composition of the present invention preferably has an Al2O3 / Cr2O3 mass ratio of more than 150.

[0017] The glass fiber composition of the present invention preferably has an MgO / Cr2O3 mass ratio of 20 or more.

[0018] The glass fiber composition of the present invention preferably has an R2O / P2O5 mass ratio of 0.01 or more.

[0019] The forming temperature Tx of the glass fiber composition of the present invention is preferably 1400°C or lower. By doing so, since it becomes possible to fiberize at a low temperature, the service life of the fiberizing equipment such as bushings can be extended, and the production cost can be reduced.

[0020] 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 more. By doing so, it becomes possible to improve the productivity of the glass fiber composition. The liquidus temperature Ty is the temperature at which crystals (primary phase) precipitate after putting glass powder that passes through a standard sieve of 30 mesh (mesh opening 500 μm) and remains on a standard sieve of 50 mesh (mesh opening 300 μm) into a platinum boat and holding it in a temperature gradient furnace for 16 hours, and then measuring the temperature.

[0021] The glass fiber composition of the present invention preferably has an elastic modulus E of 80 GPa or more. By doing so, it is possible to obtain a glass fiber-containing composite material with a small strain with respect to stress and high physical strength.

[0022] The glass fiber of the present invention is characterized by containing any of the above glass fiber compositions.

[0023] The glass fiber-containing composite material of the present invention is characterized by being a composite of the above glass fiber and a matrix material.

Effects of the Invention

[0024] According to the present invention, it is possible to provide a glass fiber composition having a high elastic modulus and good productivity.

Modes for Carrying Out the Invention

[0025] The glass fiber composition of the present invention contains 10 ppm or more of Cr2O3 by mass%, and is characterized in that the mass ratio of Al2O3 / Cr2O3 exceeds 150. The reasons for limiting the glass composition as above are shown below. In the description of the content of each component below, unless otherwise specified, “%” means “mass%”.

[0026] Cr2O3 is a component that does not affect the viscosity of molten glass but improves the elastic modulus of the glass, and can efficiently improve the elastic modulus of the glass without changing the melting conditions. By improving the elastic modulus (or specific elastic modulus) of the glass, it becomes possible to increase the mechanical strength of the glass fiber-containing composite material. Therefore, the lower limit of the 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, more than 35 ppm, particularly preferably 36 ppm or more. On the other hand, if the content becomes too high, devitrification of the Cr2O3-Al2O3-MgO system precipitates in the glass, resulting in a decrease in productivity. Therefore, the upper limit of the Cr2O3 content is preferably 10000 ppm or less, 8000 ppm, 6000 ppm or less, 5000 ppm or less, 4000 ppm or less, 3000 ppm or less, 2000 ppm or less, 1000 ppm or less, less than 1000 ppm, 990 ppm or less, 980 ppm or less, 970 ppm or less, 960 ppm or less, 950 ppm or less, 940 ppm or less, 930 ppm or less, 920 ppm or less, 910 ppm or less, 900 ppm or less, less than 900 ppm, 850 ppm or less, 800 ppm or less, 750 ppm or less, particularly preferably 700 ppm or less.

[0027] To suppress the precipitation of devitrification of the Cr2O3-Al2O3-MgO system, the ratio of Al2O3 to Cr2O3 becomes an important parameter. If this ratio is too low, devitrification of the Cr2O3-Al2O3-MgO system precipitates, and the liquidus temperature Ty tends to increase and the temperature difference ΔTxy tends to decrease. As a result, the productivity of the glass fiber decreases. Therefore, the lower limit of Al2O3 / Cr2O3 is preferably more 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, particularly preferably more than 200. In addition, if Al2O3 / Cr2O3 is too large, conversely, devitrification of the Cr2O3-Al2O3-MgO system tends to precipitate, so the upper limit is preferably 10000 or less, 8000 or less, 6000 or less, particularly preferably 5000 or less.

[0028] To suppress the precipitation of devitrification in the Cr2O3 - Al2O3 - MgO system, the ratio of MgO to Cr2O3 is as important as Al2O3 / Cr2O3. If the ratio of MgO to Cr2O3 is too low, devitrification in the Cr2O3 - Al2O3 - MgO system precipitates, and the liquidus temperature Ty tends to increase and the temperature difference ΔTxy tends to decrease. As a result, the productivity of glass fibers decreases. Therefore, the lower limit of MgO / Cr2O3 is 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, more than 80, 81 or more, 82 or more, 85 or more, 90 or more, 95 or more, 100 or more, more than 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, particularly preferably more than 120. In addition, if MgO / Cr2O3 is too large, devitrification in the Cr2O3 - Al2O3 - MgO system tends to precipitate instead, so the upper limit is 10000 or less, 8000 or less, 6000 or less, 5000 or less, 4000 or less, 3900 or less, 3800 or less, 3700 or less, 3600 or less, 3500 or less, 3400 or less, 3300 or less, 3200 or less, 3100 or less, particularly 3000 or less.

[0029] Hereinafter, the components that the glass fiber composition of the present invention may contain will be described.

[0030] Na2O is a component that suppresses the precipitation of devitrification in the Cr2O3 - Al2O3 - MgO system. Furthermore, it is a component that reduces the viscosity during glass melting to promote defoaming and lowers the forming temperature Tx during glass fiber forming. The lower limit of the Na2O content is 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 more than 0.01% is preferred. On the other hand, if the Na2O content is too high, the elastic modulus tends to decrease. Therefore, the upper limit of the Na2O content is 2% or less, less than 2%, 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, less than 1%, 0.9% or less, 0.8% or less, less than 0.8%, 0.7% or less, less than 0.7%, 0.65% or less, 0.6% or less, 0.55% or less, and particularly preferably 0.5% or less.

[0031] Li2O is a component that suppresses the precipitation of devitrification in the Cr2O3 - Al2O3 - MgO system. Furthermore, it is a component that reduces the viscosity during glass melting to promote defoaming and lowers the forming temperature Tx during glass fiber forming. On the other hand, since Li2O is expensive, if the Li2O content is too high, the production cost will increase. Therefore, the upper limit of the Li2O content is 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 the Li2O content is 0% or more, and particularly preferably 0.0001% or more.

[0032] K2O is a component that suppresses the precipitation of devitrification in the Cr2O3 - Al2O3 - MgO system. Furthermore, it is a component that reduces the viscosity during glass melting to promote defoaming and lowers the forming temperature Tx during glass fiber forming. The lower limit of the K2O content is 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 more 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 the K2O content is 5% or less, less than 5%, 4.5% or less, 4% or less, 3.5% or less, 3% or less, less than 3%, 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, 2.1% or less, 2% or less, less than 2%, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, and particularly preferably less than 1.5%.

[0033] In addition, the lower limit of the R2O content is 0% or more. However, in order to suppress the precipitation of devitrification in the Cr2O3 - Al2O3 - MgO system, reduce the viscosity during glass melting to promote defoaming, and obtain the effect of lowering the forming temperature Tx during glass fiber forming, it 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 more than 0.05%. On the other hand, from the perspective of suppressing the decrease in the elastic modulus of the glass, the upper limit of the R2O content is 2% or less, less than 2%, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, 1.5% or less, less than 1.5%, 1.4% or less, 1.3% or less, 1.2% or less, 1.1% or less, 1% or less, less than 1%, 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, less than 0.5%, 0.4% or less, 0.3% or less, and particularly preferably 0.2% or less. Here, R2O means the total amount of Li2O, Na2O, and K2O.

[0034] Since P2O5 can suppress the precipitation of devitrification in the Cr2O3 - Al2O3 - MgO system while maintaining Tx, it is a component that can effectively increase the temperature difference ΔTxy. Also, since P2O5 is a component that is not easily volatilized, it is easy to adjust the content during melting, and as a result, it is easy to adjust the temperature. The lower limit of the 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 more than 400 ppm. On the other hand, if the content of P2O5 is too high, the elastic modulus tends to decrease. Therefore, the upper limit of the P2O5 content is 2000 ppm or less, 1500 ppm or less, 1400 ppm or less, 1300 ppm or less, 1200 ppm or less, 1100 ppm or less, 1050 ppm or less, particularly preferably 1000 ppm or less.

[0035] If the ratio of R2O to P2O5 (R2O / P2O5) is too low, the forming temperature Tx becomes high, the damage to the noble metal bushing becomes severe, the replacement frequency increases, and the production cost becomes high. Therefore, the lower limit of R2O / P2O5 is 0.01 or more, 0.05 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1 or more, more than 1, 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, more than 1.5, 1.6 or more, 1.7 or more, 1.8 or more, 1.9 or more, particularly preferably 2 or more. In addition, if R2O / P2O5 is too large, the elastic modulus tends to decrease or ΔTxy tends to become small. Therefore, it is preferably 2000 or less, 1000 or less, 200 or less, 100 or less, 50 or less, 20 or less, particularly preferably 10 or less.

[0036] SiO2 is the main component that forms the glass skeletal structure. It is also a component that improves the mechanical strength and acid resistance of the glass. If the content of SiO2 is too low, the elastic modulus is likely to decrease. Therefore, the lower limit of the content of SiO2 is 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, particularly more than 58% is preferred. On the other hand, if the content of SiO2 is too high, the viscosity of the molten glass becomes too high and it becomes difficult to achieve a homogeneous molten state. As a result, it may become difficult to adjust the glass fiber diameter. Also, when the viscosity is high, the energy required for melting the glass increases, and the forming temperature Tx becomes high, the damage to the noble metal bushing becomes severe, the replacement frequency increases, and the production cost becomes high. Therefore, the upper limit of the content of SiO2 is 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, 63% or less, particularly less than 63% is preferred.

[0037] Al2O3 is a component that enhances the chemical durability and mechanical strength of glass, suppresses the precipitation of crystals and the formation of phase separation in molten glass, and improves the elastic modulus of glass. If the content of Al2O3 is too low, the elastic modulus is likely to decrease. The lower limit of the content of Al2O3 is 13% or more, 13.5% or more, 14% or more, 14.5% or more, 15% or more, more 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, more 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, particularly preferably 17.7% or more. On the other hand, if the content of Al2O3 is too high, devitrified crystals of mullite (3Al2O3·2SiO2) mainly composed of Al2O3 are likely to occur in molten glass, and furthermore, the viscosity of molten glass becomes too high and it becomes difficult to obtain a homogeneous molten state. As a result, the dimensional accuracy of the glass fiber diameter is likely to decrease. In addition, the energy required for melting the glass increases, the forming temperature Tx becomes higher, the damage to the noble metal bushing becomes severe, the replacement frequency increases, and the production cost becomes higher. Therefore, the upper limit of the content of Al2O3 is 25% or less, less than 25%, 24.5% or less, 23% or less, 22.5% or less, 22% or less, 21.5% or less, 21% or less, 20.5% or less, 20% or less, particularly preferably less than 20%.

[0038] MgO is a component that functions as a flux to facilitate melting of glass raw materials. It has the function of reducing the viscosity during glass melting to promote defoaming and lowering the forming temperature Tx. It is also a component that improves the elastic modulus and specific elastic modulus of the glass. If the content of MgO is too low, the viscosity of the molten glass becomes too high, making it difficult to achieve a homogeneous molten state. As a result, the dimensional accuracy of the glass fiber diameter is likely to decrease. Also, the forming temperature Tx increases, the energy required for glass melting increases, the damage to the noble metal bushing becomes severe, the replacement frequency increases, and the production cost becomes high. Moreover, the elastic modulus and specific elastic modulus tend to be low. Therefore, the lower limit of the content of MgO 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, particularly more than 10%, more preferably more than 10.1%, more preferably more than 10.2%, more preferably more than 10.3%, more preferably more than 10.4%, more preferably more than 10.5%, more preferably more than 10.6%, more preferably more than 10.7%, more preferably more than 10.8%, more preferably more than 10.9%, more preferably 11% or more. On the other hand, if the content of MgO is too high, in a glass composition with a high content of Al2O3, devitrification crystals of cordierite (2MgO·2Al2O3·5SiO2) are likely to form in the molten glass, which may cause nozzle clogging of the bushing during glass fiber forming. Therefore, the upper limit of the content of MgO 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, 13% or less, less than 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, 12.1% or less, particularly preferably 12% or less.

[0039] CaO, like the MgO component, is a component that functions as a flux to facilitate the melting of glass raw materials. It reduces the viscosity during glass melting, promotes defoaming, and lowers the forming temperature Tx during glass fiber forming. If the CaO content is too low, the viscosity of the molten glass becomes too high, making it difficult to achieve a homogeneous molten state. As a result, the dimensional accuracy of the glass fiber diameter is likely to decrease. Also, the forming temperature Tx increases, the energy required for glass melting increases, the damage to the noble metal bushing becomes severe, the replacement frequency increases, and the production cost rises. Therefore, the lower limit of the CaO content is preferably 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, 7.1% or more, 7.2% or more, 7.3% or more, 7.4% or more, particularly 7.5% or more. On the other hand, if the CaO content is too high, devitrification crystals of wollastonite (CaO·SiO2) or diopside (2CaO·2Al2O3·5SiO2) are likely to form in the molten glass, which may cause nozzle clogging of the bushing during glass fiber forming. Furthermore, the elastic modulus and specific elastic modulus tend 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, particularly 12% or less.

[0040] In terms of mass ratio, if the MgO / CaO is too low, devitrified crystals of wollastonite (CaO·SiO2) are likely to form in the molten glass, which may cause nozzle clogging of the bushing during the forming of glass fibers. Also, the forming temperature Tx increases, the energy required for melting the glass increases, the damage to the noble metal bushing becomes severe, the replacement frequency rises, and the production cost tends to increase. Therefore, the lower limit of MgO / CaO is preferably 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, 1.0 or more, 1.05 or more, particularly 1.1 or more. On the other hand, if the MgO / CaO is too large, in a glass composition with a high Al2O3 content, devitrified crystals of cordierite (2MgO·2Al2O3·5SiO2) are likely to form in the molten glass, which may cause nozzle clogging of the bushing during the forming of glass fibers. Also, the forming temperature Tx increases, the energy required for melting the glass increases, the damage to the noble metal bushing becomes severe, the replacement frequency rises, and the production cost increases. Therefore, the upper limit of MgO / CaO is preferably 4 or less, 3.5 or less, 3 or less, 2.5 or less, 2.4 or less, 2.3 or less, 2.2 or less, 2.1 or less, 2 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.65 or less, particularly less than 1.65.

[0041] B2O3, like SiO2, is a component that forms the framework in the glass network structure. It has the function of reducing the viscosity of the glass to promote defoaming, further lowering the melting temperature and forming temperature Tx of the glass, and improving the solubility of the glass. However, if the content of B2O3 is too high, the elastic modulus will decrease, the evaporation amount of the boron component during melting will increase, which will not only corrode the equipment but also pollute the surrounding environment. The upper limit of the content of B2O3 is less than 3%, 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, 2.1% or less, 2%, 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, less than 1%, 0.9% or less, 0.8% or less, 0.75% or less, 0.7% or less, 0.65% or less, 0.6% or less, 0.55% or less, 0.5% or less, less than 0.5%, 0.45% or less, 0.45% or less, particularly preferably less than 0.45%. On the other hand, the lower limit of the content of B2O3 is preferably 0% or more, particularly preferably 0.01% or more.

[0042] TiO₂ is a component that improves the elastic modulus of glass. Also, in the SiO₂ - Al₂O₃ - MgO composition system, TiO₂ has the function of lowering the devitrification temperature of mullite (3Al₂O₃·2SiO₂) or cordierite (2MgO·2Al₂O₃·5SiO₂). Furthermore, since it can lower the melting temperature, forming temperature Tx, and viscosity of the glass, it is possible to maintain the elastic modulus of the obtained glass while maintaining good productivity. Therefore, the lower limit of the 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, more 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, particularly more than 1.2%. On the other hand, since TiO₂ raw materials are expensive, if the TiO₂ content is too high, the production cost will increase. Therefore, the upper limit of the TiO₂ 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%, less than 2%, less than 1.9%, less than 1.8%, 1.7% or less, particularly less than 1.7%.

[0043] The glass fiber composition of the present invention may contain the following components in addition to the above components.

[0044] SrO and BaO are components that lower the high-temperature viscosity. However, if the content of SrO and / or BaO is too high, the phase separation property of the molten glass tends to increase. The upper limit of the 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, particularly preferably 0.5% or less. On the other hand, the lower limit of the 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, particularly preferably 0.05% or more. The upper limit of the 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, particularly preferably 0.5% or less. On the other hand, the lower limit of the BaO content is preferably 0% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, particularly preferably 0.005% or more.

[0045] If R’O is too low, the viscosity of the molten glass will increase, the forming temperature Tx will rise, the energy required for glass melting will increase, the damage to the noble metal bushing will become severe, the replacement frequency will increase, and the production cost will rise. Furthermore, the elastic modulus of the glass is likely 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, particularly 15% or more. On the other hand, if R’O is too high, devitrification crystals such as cordierite (2MgO·2Al2O3·5SiO2) and wollastonite (CaO·SiO2) are likely to form in the molten glass, which may cause nozzle clogging of the bushing 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.

[0046] ZrO2 is a component that improves the elastic modulus of the glass, similar to the TiO2 component. The lower limit of the ZrO2 content is preferably 0% or more, 0.001% or more, 0.002% or more, 0.003% or more, 0.004% or more, particularly 0.005% or more. On the other hand, if the ZrO2 content is too high, it may increase the devitrification precipitation temperature of mullite (3Al2O3·2SiO2) or cordierite (2MgO·2Al2O3·5SiO2) in the SiO2-Al2O3-MgO composition system glass melt. Therefore, the upper limit of the ZrO2 content is 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, particularly 0.1% or less.

[0047] Fe2O3 is a component that improves the elastic modulus of the glass, similar to the ZrO2 and TiO2 components. The lower limit of the Fe2O3 content is 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, preferably 0.25% or more. On the other hand, if the Fe2O3 content is too high, Fe2O3-based devitrified crystals are likely to form in the molten glass, which may cause nozzle clogging of the bushing during glass fiber forming. The upper limit of the Fe2O3 content is 3% or less, 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, 2.1% or less, 2% or less, 1.9% or less, 1.8% or less, 1.7% or less, 1.6% or less, particularly preferably 1.5% or less.

[0048] Y2O3 is a component that improves the elastic modulus of the glass. However, if the Y2O3 content is too high, the density increases. Therefore, the Y2O3 content is preferably 2% or less, 1.5% or less, 1% or less, less than 1%, 0.5% or less, less than 0.5%, 0.1% or less, particularly less than 0.1%.

[0049] Also, for the purpose of improving clarity, any one or more selected from SnO2, As2O3, Sb2O3, F2, CeO2, SO3, Cl2 may be contained. The content of each is preferably 0 to 2%, 0 to 1%, particularly 0 to 0.8%.

[0050] For the improvement of meltability, elastic modulus, alkali resistance, acid resistance, water resistance, forming temperature, and liquidus temperature, ZnO, MnO, La2O3, WO3, Nb2O5, etc. may be contained up to 2% each as components other than the above-mentioned components as required.

[0051] Furthermore, H2, O2, CO2, CO, H2O, He, Ne, Ar, N2, etc. may be contained up to 0.5% each. Also, noble metal elements such as Pt, Rh, Au, etc. may be contained up to 500 ppm in the glass.

[0052] As preferable composition examples of the glass fiber composition, those containing, in mass %, 10 to 6000 ppm of Cr2O3, 50 to 70% of SiO2, 15 to 20% of Al2O3, 1.2 to 15% of MgO, 3 to 15% of CaO, less than 3% of B2O3, less than 3% of TiO2, and less than 0.8% of Na2O can be mentioned. In this composition, it is preferable that the mass ratio of Al2O3 / Cr2O3 exceeds 150. Further, in this composition, it is preferable that the mass ratio of MgO / Cr2O3 is 100 or more. Further, in this composition, it is preferable that the mass ratio of R2O / P2O5 is 0.01 or more.

[0053] Next, the characteristics of the glass fiber composition of the present invention will be described.

[0054] The glass fiber composition of the present invention preferably has a forming temperature Tx of 1400 °C or lower, 1390 °C or lower, 1385 °C or lower, 1380 °C or lower, 1375 °C or lower, 1370 °C or lower, 1369 °C or lower, 1368 °C or lower, 1367 °C or lower, 1366 °C or lower, particularly 1365 °C or lower. If the forming temperature Tx is too high, the energy required for melting the glass increases, the damage to the noble metal bushing becomes severe, the replacement frequency increases, and the production cost becomes high. The lower limit of the forming temperature Tx is not particularly limited, but is realistically 1100 °C or higher.

[0055] The glass fiber composition of the present invention preferably has a liquidus 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, particularly 1265 °C or lower. If the liquidus temperature Ty is too high, the temperature difference ΔTxy tends to become small, so the productivity tends to deteriorate. The lower limit of the liquidus temperature Ty is not particularly limited, but is realistically 1000 °C or higher.

[0056] The temperature difference ΔTxy between the forming temperature Tx and the liquidus temperature Ty of the glass fiber composition of the present invention is preferably 30°C or more, 40°C or more, 45°C or more, 50°C or more, 55°C or more, 60°C or more, 65°C or more, 70°C or more, 75°C or more, 80°C or more, 85°C or more, particularly more than 85°C. If the temperature difference ΔTxy is too small, devitrified substances that cause nozzle clogging of the bushing are likely to occur during glass fiber forming, resulting in a decrease in productivity. The upper limit of the temperature difference ΔTxy is not particularly limited, but is realistically 180°C or less.

[0057] The elastic modulus E of the glass fiber composition of the present invention is preferably 80 GPa or more, 81 GPa or more, 82 GPa or more, 83 GPa or more, 84 GPa or more, 85 GPa or more, 86 GPa or more, 87 GPa or more, 88 GPa or more, 89 GPa or more, 90 GPa or more, 91 GPa or more, 92 GPa or more, particularly 93 GPa or more. If the elastic modulus E is too low, it becomes difficult to achieve high functionality (specifically, improvement in mechanical strength) of the glass fiber-containing composite material. The upper limit of the elastic modulus E is not particularly limited, but is realistically 150 GPa or less.

[0058] The lower limit of the density ρ of the glass fiber composition of the present invention is 2 g / cm 3 or more, 2.1 g / cm 3 or more, 2.2 g / cm 3 or more, 2.3 g / cm 3 or more, 2.4 g / cm 3 or more, 2.5 g / cm 3 or more, 2.55 g / cm 3 or more, particularly 2.6 g / cm 3 or more is preferable. If the density ρ is too low, the elastic modulus E is likely to decrease. On the other hand, if the density ρ is too high, it becomes difficult to achieve high functionality (specifically, weight reduction) of the glass fiber-containing composite material. Therefore, the upper limit of the density ρ is 3 g / cm 3 or less, 2.9 g / cm 3 or less, 2.8 g / cm 3 or less, particularly 2.7 g / cm 3 or less is preferable.

[0059] The glass fiber composition of the present invention preferably has a specific elastic modulus calculated by 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, particularly 36 or more. On the other hand, if the specific elastic modulus is too low, it becomes difficult to achieve high functionality (specifically, both weight reduction and improvement of mechanical strength) of the glass fiber-containing composite material. The upper limit value of the specific elastic modulus is not particularly limited, but is realistically 45 or less.

[0060] In order to reduce the viscosity of the melt of the glass fiber composition of the present invention and promote clarification, the moisture content β-OH contained in the glass fiber composition is 0.001 mm -1 or more, 0.005 mm -1 or more, 0.01 mm -1 or more, 0.015 mm -1 or more, 0.02 mm -1 or more, 0.025 mm -1 or more, particularly 0.03 mm -1 or more is preferable. On the other hand, if the moisture content β-OH is too high, the generation of bubbles due to clarification increases in the glass melt, the glass fiber is likely to be cut, and the productivity tends to decrease. Therefore, the upper limit value of the moisture content β-OH is 1 mm -1 or less, 0.95 mm -1 or less, 0.90 mm -1 or less, 0.85 mm -1 or less, 0.8 mm -1 or less, 0.75 mm -1 or less, 0.7 mm -1 or less, 0.65 mm -1 or less, 0.6 mm -1 or less, particularly 0.55 mm -1 or less is preferable.

[0061] Next, the glass fiber and the glass fiber-containing composite material of the present invention will be described.

[0062] The glass fibers of the present invention preferably contain 95% or more, in terms of solid content, of glass composed of the glass fiber composition described above. If 95% by mass or more of the glass fibers of the present invention are glass composed of the glass fiber composition described above and the balance is an organic substance such as a coating agent, scratches are less likely to occur on the surface of the glass fibers in various processing steps such as the weaving step of the glass fibers, and stable strength performance can be maintained. Further, the glass fibers can sufficiently exhibit various physical and chemical performances. The content of the glass composed of the glass fiber composition in the glass fibers of the present invention is 95 to 100% by mass in terms of solid content, preferably less than 95.5 to 100% by mass, 96 to 99.99% by mass, particularly preferably less than 96.5 to 99.99% by mass. Here, the solid content conversion is performed by measuring the mass of the glass fibers in a dried state such that the moisture on the glass surface is less than 0.1% by mass, and further performing heat treatment at a high temperature to heat-remove the organic substances applied to the glass fiber surface, and then calculating by measuring the mass of only the glass.

[0063] In addition, when the glass fiber composition is less than 95% by mass in terms of solid content, the performance of the organic substance applied to the surface to protect the glass fibers does not particularly improve, and the amount of the organic substance required for coating increases, so the manufacturing cost increases and it is not economical. Further, when the glass fiber composition exceeds 99.99% by mass in terms of mass% in solid content conversion, the protective performance on the glass fiber surface may not be sufficiently achieved.

[0064] Further, the cross-sectional shape of the glass fibers of the present invention perpendicular to the drawing direction during spinning may be, in addition to a circular shape, an elliptical shape, a track shape, a flat shape, a rectangular shape, a mayu shape, and a polygonal shape, etc., which are cross-sectional shapes of irregular shapes.

[0065] Further, the product form of the glass fibers of the present invention is preferably any one of chopped strands, yarns, and rovings. In this way, it can be used for various applications.

[0066] Here, the chopped strand is a fiber obtained by cutting a glass fiber bundle to a predetermined length, the yarn is a continuous glass fiber that has been twisted, and the roving is a strand of glass fiber bundles aligned side by side.

[0067] Regarding the chopped strand, its fiber length and fiber diameter are not limited, and those suitable for the application can be selected. Also, any manufacturing method for the chopped strand can be adopted. The glass strand obtained by spinning molten glass can be directly cut into short fibers, or the glass strand obtained by spinning molten glass can be wound up as long fibers to form a cake, and then the glass strand can be drawn from the cake and cut by a cutting device. In this case, any cutting method can be adopted. For example, it is possible to use an outer peripheral blade cutting device, an inner peripheral blade cutting device, a hammer mill, etc. The obtained chopped strand can be randomly laminated on a plane and bonded with a binder to form a sheet, or it can be randomly integrated three-dimensionally. Also, it may be a glass masterbatch (GMB) pellet containing a high content of glass fibers, or a pellet-shaped LFTP (long fiber reinforced thermoplastic resin) in which the glass fibers are oriented in the same direction.

[0068] Regarding the yarn, as long as it has a predetermined twist, including untwisted yarn, there are no particular limitations on the twist magnitude, direction, etc.

[0069] Also, regarding the roving, as long as it is a strand of glass fiber bundles aligned side by side to form a bundle and wound up in a cylindrical shape, there is no problem with any appearance, and the wound fiber diameter and the number of aligned strands are not limited.

[0070] In addition to the above, the glass fiber of the present invention can also be used in the form of continuous strand mat, bonded mat, cloth, tape, woven fabric, or milled fiber. It can also be made into a prepreg impregnated with resin. Moreover, regarding the usage method, molding method, etc. for applying the glass fiber, it can also be applied to spray-up, hand lay-up, filament winding, injection molding, centrifugal molding, roller molding, or BMC and SMC methods using a matched die.

[0071] Furthermore, various surface treatment agents can be applied to the glass fiber of the present invention to impart desired performance. For example, sizing agents, binders, coupling agents, lubricants, antistatic agents, emulsifiers, emulsion stabilizers, pH adjusters, defoamers, colorants, antioxidants, fungicides, or stabilizers, etc. can be applied in an appropriate amount and coated on the surface of the glass fiber either alone or in any combination of multiple types. Also, such surface treatment agents or coating agents can be either starch-based or plastic-based. For example, for sizing agents for FRP, acrylic, epoxy, urethane, polyester, vinyl acetate, vinyl acetate-ethylene copolymer, etc. can be appropriately used.

[0072] The glass fiber-containing composite material of the present invention is a composite of the above glass fiber and a matrix material. As the matrix material, either an organic matrix material or an inorganic matrix material may be used.

[0073] The organic matrix material is represented by organic resins such as thermoplastic resins and thermosetting resins, and it is possible to appropriately use the most suitable resin alone or in combination of multiple types according to the application.

[0074] Examples of the above 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, polyvinyl chloride resins, etc.

[0075] Examples of the above-mentioned thermosetting resin include epoxy resins, thermosetting modified polyphenylene ether resins, thermosetting polyimide resins, urea resins, allyl resins, silicone resins, benzoxazine resins, phenolic resins, unsaturated polyester resins, bismaleimide triazine resins, alkyd resins, furan resins, melamine resins, polyurethane resins, aniline resins, and the like.

[0076] Examples of the inorganic matrix material include concrete or mortar. Concrete is a mixture of cement, sand, gravel, and water, and mortar is a mixture of cement, sand, and water. The mixing ratios of the various components constituting the concrete and mortar and the type of cement are not particularly limited. Fly ash and the like can also be added.

[0077] In the glass fiber-containing composite material, in addition to glass fibers, other structural reinforcing materials such as carbon fibers, ceramic fibers, and bead materials can also be contained.

[0078] 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 TV or a personal computer, it is suitable for use as a liquid crystal spacer used to maintain the distance between two substrate glasses because the fiber diameter of the glass fiber has stable dimensional accuracy.

[0079] Furthermore, the glass fiber composition and the glass fiber of the present invention can be recycled. That is, through a remelting process from an article containing the glass fiber composition and the glass fiber of the present invention, it may be formed into a fiber shape or various shapes other than fibers such as spherical or granular shapes and used for other purposes. For example, it can also be used as a soil additive, a concrete additive or aggregate, an asphalt additive, and the like.

[0080] Next, the manufacturing method of the glass fiber of the present invention will be described.

[0081] First, in order to obtain the above composition (and properties), the prepared glass raw material batch is charged into a glass melting furnace, vitrified, melted, and homogenized. The composition is as described above, and the description is omitted here.

[0082] Subsequently, the molten glass is spun into glass fibers. Specifically, the molten glass is supplied to a bushing. The molten glass supplied to the bushing is continuously drawn out in a filament form from a large number of bushing nozzles provided on the bottom surface thereof. Various treatment agents are applied to the monofilaments thus drawn out, and the glass fibers are obtained by bundling them for each predetermined number.

[0083] The glass fibers of the present invention thus formed are processed into chopped strands, yarns, rovings, etc., and are used for various applications.

Examples

[0084] Hereinafter, the present invention will be described in detail based on examples. It should be noted that the following examples are merely illustrative, and the present invention is not limited to the following examples at all.

[0085] (Composition for Glass Fibers) Tables 1 to 9 show examples (Sample Nos. 1 to 38, 40 to 60) and comparative examples (Sample No. 39) of the composition for glass fibers of the present invention.

[0086]

Table 1

[0087]

Table 2

[0088]

Table 3

[0089]

Table 4

[0090]

Table 5

[0091]

Table 6

[0092]

Table 7

[0093]

Table 8

[0094]

Table 9

[0095] Each sample was prepared as follows.

[0096] First, various glass raw materials were weighed and mixed in predetermined amounts using arbitrary natural raw materials and / or chemical raw materials so as to obtain the glass compositions in the table, thereby preparing a glass batch. Next, this glass batch was put into a platinum-rhodium crucible and heated and melted at 1550°C for 5 hours in an air atmosphere. In addition, in order to obtain a homogeneous molten glass, the molten glass was stirred using a heat-resistant stirring rod during the heating and melting.

[0097] Thereafter, the molten glass in a homogeneous state was poured into a carbon mold and cast into a predetermined shape, and a slow cooling operation was performed to obtain a final glass sample for measurement.

[0098] The physical properties of the obtained glass samples were measured by the following procedure.

[0099] The forming temperature Tx (the viscosity of the molten glass is 103 The temperature corresponding to dPa·s was measured as follows. After putting a glass sample into an alumina crucible and heating it to a molten state, a viscosity curve was created from the viscosity data at each temperature measured based on the platinum ball pulling-up method. From the obtained viscosity curve, the temperature at which the viscosity of the molten glass becomes 10 3 dPa·s was calculated by interpolation and defined as the forming temperature Tx.

[0100] The liquidus temperature Ty was measured as follows. Glass powder that passed through a standard sieve of 30 mesh (300 μm) and remained on a standard sieve of 50 mesh (300 μm) was filled into a platinum container to have an appropriate bulk density, and placed in an indirectly heated temperature gradient furnace with a maximum temperature set to 1320°C and left standing, and heat treatment was performed in an air atmosphere for 16 hours. After the glass sample was cooled to room temperature, the glass sample was observed with a polarized light microscope, and the temperature corresponding to the location where crystals (primary phase) began to precipitate was calculated from the temperature gradient in the indirectly heated furnace and defined as the liquidus temperature Ty.

[0101] The temperature difference ΔTxy between the forming temperature Tx and the liquidus temperature Ty was calculated as (forming temperature Tx) - (liquidus temperature Ty).

[0102] The elastic modulus E was obtained by annealing a plate-shaped sample with dimensions of 40 mm × 20 mm × 2 mm polished with a polishing liquid in which 1200-grade alumina powder was dispersed using a general annealing furnace, and then measuring both surfaces at room temperature using a free resonance type elastic modulus measuring device (manufactured by Nippon Techplus Co., Ltd.).

[0103] The density ρ was measured by the well-known Archimedes' method using a sample annealed using a general annealing furnace.

[0104] The specific elastic modulus was calculated as (elastic modulus E) / (density ρ).

[0105] As is clear from Tables 1 to 9, for Samples No. 1 to 38 and 40 to 60 which are examples, the elastic modulus E was 90.1 GPa or more and the temperature difference ΔTxy was 27°C or more. Regarding the influence of Cr2O3 and Al2O3 on the elastic modulus E and the temperature difference ΔTxy, it can be considered as follows. For example, comparing Samples No. 34 and 36, it can be seen that the elastic modulus E improves as the content of Cr2O3 increases. On the other hand, as Al2O3 / Cr2O3 decreases, the liquidus temperature Ty increases and the temperature difference ΔTxy decreases. Thus, it can be understood that by appropriately adjusting the Cr2O3 content and the ratio of Al2O3 / Cr2O3, a high elastic modulus E can be achieved while maintaining the temperature difference ΔTxy.

[0106] On the other hand, for No. 39 which is a comparative example, Al2O3 / Cr2O3 was as low as 150 and devitrification of the Cr2O3 - Al2O3 - MgO system precipitated. As a result, the temperature difference ΔTxy became as low as -11°C.

[0107] (Glass fiber and glass fiber-containing composite material) After melting the glass fiber composition having the composition of Sample No. 1 of Example 1, by using a bushing device having a platinum nozzle, glass monofilaments having a diameter of 3 μm could be continuously formed. Since yarn breakage hardly occurred even when continuously formed in this way, it was possible to obtain glass monofilaments with a stable fiber diameter.

[0108] Next, an appropriate amount of a sizing agent containing a silane coupling agent or the like was applied to the surfaces of a plurality of glass monofilaments obtained by forming using the above-described bushing device by the dipping method and air-dried to obtain glass fibers (glass strands). A plurality of glass fibers were bundled, impregnated with an organic solvent made of polypropylene resin and solidified, and cut to a desired length to obtain pellet-shaped LFTP in which the glass fibers were oriented in the same direction.

[0109] By using the thus obtained LFTP, the length of the glass fibers in the glass fiber-containing composite material can be increased, making it possible to obtain a high-strength glass fiber-containing composite material. For example, it becomes possible to increase the flexural strength and the like of a plate-like object.

Industrial Applicability

[0110] The glass fibers and glass fiber-containing composite materials produced using the glass fiber composition of the present invention can be expected to be used in various applications. For example, in aircraft applications, it can be used for aircraft base materials, interior materials, vibration-proof materials, etc. In in-vehicle related applications, it can be used for vibration damping and reinforcement materials, bumpers, engine undercovers, fenders, roof materials, bodies, spoilers, muffler filters, dashboards, radiators, timing belts, etc. In ship-related applications, it can be used for the bodies of motorboats, yachts, fishing boats, etc. In construction, civil engineering, and building materials related applications, it can be used for decorative walls, light ceilings and lighting covers, front pasted cloths, insect-proof nets, roll blinds, tent membrane materials, backlit signboards, daylighting corrugated sheets, flat sheets, folded sheets, concrete anticorrosion and reinforcement materials, exterior wall reinforcement materials, coating waterproof materials, smoke-proof walls, non-combustible transparent partitions, projection films, road reinforcement materials, bathtubs, bathtub and toilet units, etc. In leisure and sports related applications, it can be used for fishing rods, tennis rackets, golf clubs, ski boards, helmets, etc. In electronic device related applications, it can be used for printed wiring boards, insulating boards, terminal boards, substrates for ICs, housing materials for electronic devices, package materials for electronic components, housing materials for optical devices, package materials for optical components, insulating supports, etc. In industrial facility related applications, it can be used for windmill blades, glass filter bags, outer covering materials for non-combustible heat insulating materials, reinforcement materials for resinoid grindstones, aluminum filter filters, etc. In agriculture related applications, it can be used for greenhouses, agricultural poles, silo tanks, etc.

Claims

1. In mass%, Cr ２ O ３ Contains 10 ppm or more and, by mass ratio, Al ２ O ３ / Cr ２ O ３ A composition for glass fibers, characterized in that the molecular weight is greater than 150.

2. Cr by mass% ２ O ３ 2. The composition for glass fibers according to claim 1, wherein the composition contains 10 to 6,000 ppm.

3. Mass ratio: MgO / Cr ２ O ３ 3. The composition for glass fibers according to claim 1, wherein the molecular weight is 20 or more.

4. In mass%, P ２ O ５ Contains 10 to 1000 ppm and has a mass ratio of R ２ O / P ２ O ５ (R ２ O is Li ２ O, Na ２ O and K ２ 3. The glass fiber composition according to claim 1, wherein the total amount of SiO and O is 0.01 or more.

5. In mass%, Na ２ 5. The glass fiber composition of claim 4 containing less than 0.8% O.

6. In mass%, SiO ２ 25-70%, Al ２ O ３ 13-25%, MgO 0.6-25%, CaO 3-15%, B ２ O ３ 3. The glass fiber composition according to claim 1, wherein the content is 0 to less than 3%.

7. In mass%, Cr ２ O ３ 10~6000ppm, SiO ２ 50-70%, Al ２ O ３ More than 15 to 20%, MgO 1.2 to 15%, CaO 3 to 15%, B ２ O ３ 0 to less than 3%, TiO ２ 0.01 to less than 3%, Na ２ A composition for glass fibers comprising less than 0.8% O.

8. In terms of mass ratio, Al ２ O ３ / Cr ２ O ３ The glass fiber composition according to claim 7, characterized in that the .lambda. is greater than 150.

9. Mass ratio: MgO / Cr ２ O ３ 9. The composition for glass fibers according to claim 7, wherein the molecular weight is 20 or more.

10. In terms of mass ratio, R ２ O / P ２ O ５ The composition for glass fibers according to claim 7 or 8, wherein is 0.01 or more.

11. 3. The composition for glass fibers according to claim 1, wherein the molding temperature Tx is 1,400° C. or lower.

12. 3. The composition for glass fibers according to claim 1, wherein a temperature difference ΔTxy between the molding temperature Tx and the liquidus temperature Ty is 30° C. or more.

13. 3. The glass fiber composition according to claim 1, wherein the elastic modulus E is 80 GPa or more.

14. A glass fiber comprising the glass fiber composition according to claim 1 or 2.

15. A glass fiber-containing composite material, which is a composite material comprising the glass fiber according to claim 14 and a matrix material.

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