Low-boron high-performance alkali-free glass fiber composition

Abstract

The present invention relates to the technical field of glass fibers. Disclosed is a low-boron high-performance alkali-free glass fiber composition. A technical solution is as follows: the composition comprises the following components in percentages by mass: 52-60% of SiO2, 11-15% of Al2O3, 2-6% of B2O3, 18-25% of CaO, 1-3% of MgO, 0.1-0.6% of Fe2O3, 0.1-2.5% of TiO2, 0.3-0.6% of F2, 0.05-0.75% of K2O, 0.05-0.75% of Na2O, and 0.1-3% of XO, wherein XO is at least one or more of FeO, SeO2, BeO, La2O3 and CeO2. In the present invention, the content of boron is reduced; moreover, by adjusting the components of glass, the stability of the glass composition under founding and forming conditions and the performance of a product are prevented from deteriorating, and the characteristics of better light transmission and a lower dielectric constant are obtained.

Description

Low boron high performance alkali-free glass fiber composition Technical Field

[0001] This invention relates to the field of glass fiber technology, and more specifically to a low-boron, high-performance, alkali-free glass fiber composition. Background Technology

[0002] Alkali-free glass, also known as E-glass, typically refers to silicate glass with an alkali metal content of no more than 0.8%. Originating in the mid-20th century, this type of glass fiber is widely used in composite materials and electrical insulation due to its superior strength and excellent chemical stability. However, traditional alkali-free glass manufacturing processes involve high boron content, and the boron-containing raw materials are mainly imported, leading to increased costs. Furthermore, the scarcity and limited availability of boron-containing raw materials makes my country vulnerable to supplier constraints, posing a challenge to the development of its glass fiber industry.

[0003] In recent years, with the increasing demands for environmental protection and low-carbon development, reducing the volatilization of boron in the manufacturing process of alkali-free glass has become particularly important. This not only helps alleviate the environmental pressure on enterprises but also helps reduce solid waste emissions, thereby achieving the goals of environmental protection and promoting low-carbon development.

[0004] Although current low-borosilicate glass fiber compositions have achieved fairly low boron content levels, glass properties and melting conditions still require further optimization. In existing technologies, as boron content decreases, glass viscosity increases, while the window temperature (i.e., the difference between the forming temperature and the crystallization temperature) becomes smaller. This not only affects the uniformity of the glass during melting but also increases the probability of glass fiber crystallization during production, thus increasing the difficulty of forming.

[0005] Furthermore, while introducing alkali metal oxides other than Na₂O and K₂O to reduce boron content is one solution, it also leads to a decrease in glass fiber performance, thus affecting product competitiveness. This performance reduction cannot meet the development needs of advanced communication technologies. Therefore, further research and development of new low-boron glass fiber compositions are needed to optimize their performance and adapt to ever-changing market demands. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a low-boron, high-performance, alkali-free glass fiber composition. While reducing the boron content, the glass composition is adjusted to ensure the stability of the melting and forming conditions and that the performance of the product does not deteriorate. It also has the characteristics of better light transmittance and lower dielectric constant.

[0007] The technical solution of this invention is as follows:

[0008] A low-boron, high-performance, alkali-free glass fiber composition comprising the following components by mass percentage: SiO2: 52-60%, Al2O3: 11-15%, B2O3: 2-6%, CaO: 18-25%, MgO: 1-3%, Fe2O3: 0.1-0.6%, TiO2: 0.1-2.5%, F2: 0.3-0.6%, K2O: 0.05-0.75%, Na2O: 0.05-0.75%, XO: 0.1-3%; wherein XO is one or more of FeO, SeO2, BeO, La2O3, and CeO2.

[0009] In this invention, SiO2 is the network generator of the glass, forming an irregular continuous network structure with silicon-oxygen tetrahedra. This structure has high bond strength, which can effectively improve the mechanical strength, chemical stability, and thermal stability of the glass, while reducing its density. However, increasing the SiO2 content will increase the high-temperature viscosity of the glass, making fiber formation more difficult. To ensure that the elastic modulus and density meet the requirements while also satisfying the fiber formation needs, this invention limits the SiO2 mass percentage in the glass composition to 52-60%.

[0010] Al₂O₃ is a network intermediate for glass formation. 3+ It can capture non-bridging oxygen to form aluminum-oxygen tetrahedra and enter the silicon-oxygen network, reconnecting broken networks and making the glass structure more compact, which is beneficial to improving the mechanical properties and elastic modulus of the glass. However, the large-scale introduction of Al... 3+ It will promote the crystallization ability of glass, especially when the mass percentage of Al2O3 is >16%, a large number of aluminosilicate particles will be precipitated in the glass. In order to adjust the crystallization type in the glass and reduce the tendency of aluminosilicate crystallization, the present invention limits the mass percentage of Al2O3 to 11-15%.

[0011] Boron (B₂O₃) is a network-forming oxide in glass, which not only improves a range of glass properties but also has excellent fluxing properties. Under different conditions, boron can exist in the form of [BO₃]trigonal and / or [BO₄]tetrahedrons. Under high-temperature melting conditions, it is generally difficult to form [BO₄]tetrahedrons, and it exists as [BO₃]trigonal structures instead. This is the main reason why B₂O₃ can reduce high-temperature viscosity. If the B₂O₃ content is too low, it cannot effectively inhibit crystallization and reduce glass viscosity; if it is too high, it will lead to increased costs. Therefore, this invention limits the B₂O₃ mass percentage range to 2-6%.

[0012] CaO is a network exooxide that reduces high-temperature viscosity and shortens the glass's viscosity. The introduction of CaO increases phase competition, effectively suppressing the tendency for silica-alumina to crystallize in the glass. In the glass system of this invention, CaO significantly increases the glass density, but has little effect on the glass's elastic modulus. Therefore, this invention limits the CaO mass percentage content to 18-25%.

[0013] MgO is different from CaO, Mg 2+ With its small radius, high charge, and strong polarization, MgO is an intermediate oxide in glass and has a strong agglomeration effect, which can increase the degree of polymerization of the glass network. It mainly plays a role in regulating the viscosity of glass, controlling glass crystallization, and improving the elastic modulus of glass. However, excessive MgO will increase the upper limit temperature and crystallization rate of glass crystallization. This invention limits the MgO mass percentage content to a range of 1-3%.

[0014] To improve the cost-effectiveness of the product while ensuring the electrical properties of the glass, the B2O3 content can be appropriately reduced. By adjusting the amount of network formations and bridging oxygen in the glass, the competition between boron and silicon ions for oxygen in the structure can be controlled, thereby reducing the dielectric constant of the glass, improving its mechanical properties, and simultaneously taking into account the glass melting and clarification effect.

[0015] As strong oxidizing agents, CeO2 and SeO2 release oxygen when heated at high temperatures, promoting the removal of bubbles from the molten glass during the glass melting process. CeO2 and SeO2 can regulate the redox atmosphere within the kiln, effectively controlling the FeO / Fe2O3 ratio, improving the heat permeability of the molten glass, and reducing energy consumption during melting. Controlling the FeO content in the molten glass is more conducive to stabilizing the temperature of high-flow-rate baffles, which is beneficial for subsequent wire drawing operations. Considering the wire drawing operations in high-modulus kilns, this invention controls the Fe2O3 mass percentage to 0.1-0.6%. The use of CeO2 and SeO2 can replace sodium sulfate (Na2SO4) in traditional formulations, reducing the generation of sulfur-containing gases during kiln melting, reducing the corrosion of refractory materials by sulfur-containing volatile gases, and also reducing the sulfur content in the kiln exhaust gas. In the glass system of this invention, Se2O and Ce2O provide a lot of free oxygen. However, excessive Se2O and Ce2O will not only interfere with the coordination of [AlO4] and [TiO4], but also weaken the bridging oxygen in [SiO4], destroy the compactness of the structure, reduce the elastic modulus of the glass, and promote crystallization. At the same time, it will also cause the color of the glass to deepen, thus losing the optimization of the glass color.

[0016] La³ in La₂O₃ + With its large ionic radius and high polarizability, La₂O₃ enhances the ionic bond strength in glass networks, resulting in a more stable structure. This strong bonding reduces the movement of free charges, thereby lowering dielectric loss. However, excessive La₂O₃ can lead to a decrease in La³⁺. + The accumulation effect disrupts the uniformity of the glass network structure, leading to phase separation or crystallization, forming localized non-uniform regions, and reducing the light transmittance and mechanical strength of the material.

[0017] BeO, as a high-melting-point oxide (melting point approximately 2578℃), can be incorporated into the silicon-oxygen network (Si-O) during glass melting, through Be... 2+ With O 2- The strong bonding enhances the density of the glass skeleton. 2+ Its strong polarization ability can also replace some alkali metal ions (such as Na) in the glass network. + or K + This creates a more stable local charge compensation, hinders the long-range diffusion of alkali metal ions, and reduces the dielectric constant of the glass fiber. However, excessive BeO may lead to an increase in melting temperature or a decrease in fluidity.

[0018] When TiO2 melts at high temperatures, it can impart color to the glass, leading to enhanced light scattering, reduced visible light transmittance, and impact on the glass's transparency and optical uniformity. Therefore, this invention limits the TiO2 mass percentage content to a range of 0.1-2.5%.

[0019] Fe2O3 is beneficial for glass melting and can improve the crystallization properties of glass; however, excessive Fe2O3 can cause the glass to turn red or dark brown. Therefore, this invention limits the Fe2O3 mass percentage content to 0.1-0.6%.

[0020] FeO in glass affects its light transmittance and refractive index. Excessive addition may lead to a decrease in light transmittance. When combined with strong oxides, it helps to optimize the color of the glass and increase its light transmittance.

[0021] Fluorides act as highly efficient fluxes in glass melting, disrupting the silicon-oxygen network structure, significantly reducing the melting point and molten viscosity of glass, and decreasing melting energy consumption. At high temperatures, they release fluoride ions, which combine with gases (such as CO2 and SO2) in the melt, accelerating gas escape and improving the clarity and optical purity of the glass. However, excessive addition of fluorides can lead to high levels of fluoride in the furnace flue gas, increasing environmental costs during the manufacturing process. Therefore, this invention limits the F2 mass percentage range to 0.3-0.6%.

[0022] Preferably, in XO, the mass ratio of SeO2, BeO, La2O3, CeO2 to FeO is (0-3):(0-15):(0-15):(0-5):1.

[0023] Preferably, XO is FeO, SeO2, BeO, La2O3, and CeO2.

[0024] Preferably, to further ensure the modulus, the influence of CaO and MgO on the elastic modulus, density, crystallization, and viscosity of the glass is comprehensively considered, and the ratio of CaO and MgO used is adjusted to enable the glass to achieve favorable performance indicators such as higher elastic modulus, lower density, lower crystallization temperature, and crystallization rate. The present invention limits the mass percentage of CaO to 18-25% and the mass percentage of MgO to 1-3%, and controls the mass percentage of CaO and MgO to meet the mass ratio of CaO to MgO of (9-12):1.

[0025] Both K₂O and Na₂O can break down the silicon-oxygen tetrahedral structure of silicon dioxide (SiO₂), significantly reducing the melting temperature and viscosity of glass, improving melt fluidity, and shortening melting time. However, excessive K₂O and Na₂O increase the amount of free Na in the glass. + K + The quantity will lead to a decrease in the dielectric constant of the glass. Therefore, preferably, the sum of the mass percentages of K2O and Na2O is 0.4-0.8%, and the mass ratio of K2O to Na2O is (0.5-3.5):1.

[0026] Preferably, the mass percentage of B2O3 is 3-4%.

[0027] Preferably, the mass percentage of MgO is 1.9-2.3%.

[0028] Preferably, the raw materials used are pyrophyllite, dolomite, borocalcite, limestone, lanthanum hydroxide, beryllium silicate, selenium powder, cerium oxide, and recycled glass powder.

[0029] Preferably, the raw materials used are kaolin, pyrophyllite, dolomite, borocalcite, quicklime, lanthanum hydroxide, beryllium silicate, selenium powder, cerium oxide, and recycled glass powder.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. The low-boron, high-performance, alkali-free glass fiber composition of the present invention, while reducing the boron content, ensures stability under melting and forming conditions and provides superior product performance through optimization and adjustment of the glass composition. Simultaneously, the introduction of SeO2, BeO, La2O3, and CeO2 effectively improves the light transmittance of the glass fiber, reduces its dielectric constant and elastic modulus, and enhances the glass's adaptability to different application scenarios.

[0032] 2. In the low-boron high-performance alkali-free glass fiber composition of the present invention, in order to prevent insufficient uniformity of raw materials during the batching process, which would result in the quartz powder not being melted in time during the glass melting process, thus leading to poor glass melting quality and affecting product quality, the present invention does not use quartz powder, thereby improving the melting capacity of raw materials, reducing energy consumption, and reducing carbon emissions.

[0033] 3. The low-boron, high-performance, alkali-free glass fiber composition of the present invention reduces the use of boron-containing raw materials and reduces the volatilization of boron-containing substances during the melting process, which helps to reduce environmental protection costs and protect the environment.

[0034] 4. The low-boron high-performance alkali-free glass fiber prepared using the low-boron high-performance alkali-free glass fiber composition of the present invention has a melting temperature not higher than 1470℃ and a liquidus temperature not higher than 1100℃. It has good melting temperature and liquidus temperature, low crystallization rate, meets the requirements of the drawing process, and is suitable for tank furnace and large-scale production. Embodiments of the present invention

[0035] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention.

[0036] In the following embodiments, when preparing glass fibers with low boron and high performance using alkali-free glass fiber compositions, the tank furnace drawing process includes the following steps:

[0037] (1) Calculate the required mass of various raw materials according to the content of each component in the glass fiber composition, then use the raw material batching system to batch the materials according to the set ratio, and then transport them to the kiln head batching silo after uniform pneumatic mixing. Use the feeding machine to uniformly feed the batching material into the large pool kiln.

[0038] (2) The uniformly mixed batch is melted and clarified into a homogeneous glass melt in a tank furnace at a temperature of 1425°C.

[0039] (3) The molten glass flows through the furnace passage to the platinum-rhodium sprue plate, and is drawn into glass fibers of different diameters at 1230℃ through the nozzles on the sprue plate;

[0040] (4) The glass fiber is drawn into the drawing machine and formed into raw fiber product through high-speed drawing.

[0041] Examples 1-11 and Comparative Examples 1-8

[0042] The formulations of the alkali-free glass fiber compositions of Examples 1-11 and Comparative Examples 1-9 are shown in Table 1-2. Impurities are inevitably introduced, and the balance in the components represents the amount of impurities introduced, which is not shown in Table 1-2.

[0043] Table 1 Formulations of Alkali-Free Glass Fiber Compositions in Examples 1-10

[0044] Composition and Properties Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Example 10 SiO2 55.48 55.45 55.43 55.82 56.06 53.58 55.86 54.9 54.96 54.7 Al2O3 14.48 14.4 13.9 14.03 14.05 14.8 13.7 14 13.5 13.33 B2O3 4.3 4.5 24.2 3.5 3.6 25.3 35.15 4.13 3.9 4.25 CaO2 1.9 2 1.78 2 2.4422.5822.242221.422.423.0522.81MgO21.92.052.12.152.21.922.32.3Fe2O30.2830.2820.2770.290.280.270. 170.30.290.25TiO20.260.260.240.240.240.250.250.250.270.27F20.530.520.570.570.50.570.520.40.50.5K2O0 .320.230.320.330.320.320.350.220.360.36Na2O0.320.450.450.410.40.320.190.280.380.38FeO0.10.10.10.10.10.10.10.10.130.13SeO2—————0.20.2———BeO———————1——CeO2——————0.2———La2O3————————0.250.5 Elastic modulus (GPa) 80.58 1.3818 2.3828 1818 1.58 1.58 1.8 Transmittance (%) 88.589 89.589.990919 1.289 89.18 9.5 Dielectric constant 6.7 6.69 6.69 6.7 6.72 6.65 6.65 6.6 6.65 6.6 Melting temperature / ℃ 1427 1426 1424 1426 1426 1424 1425 1426 1427 1247 Upper limit temperature for crystallization / ℃ 1100 1099 1099 1100 1100 1100 1099 1100 1100 1100

[0045] Table 2 Formulations of alkali-free glass fiber compositions in Example 11 and Comparative Examples 1-8

[0046] Composition and Performance Examples 11 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 SiO2 54.57 54.02 54.57 54.57 54.15 54.57 54.92 54.67 54.47 54.2 Al2O3 13.77 13.12 13.32 13.52 13.2 13.52 13.62 13.77 13.77 14.4 B2O3 3.82 3.82 3.82 3.82 3.82 3.82 3.82 3.82 6.3 CaO2 2.48 22.08 22.48 22.48 22. 1722.4820.5822.6222.3822.7MgO2.32.12.22.32.32.242.32.30.58Fe2O30.20.20.20.20.20.20.20.20.20.291TiO20.270.270.27 0.270.270.270.270.270.270.25F20.420.420.420.420.420.420.420.420.420.5K2O0.260.260.260.260.260.260.260.150.150.2 9Na2O0.280.280.280.280.280.280.280.150.60.32FeO0.080.080.080.080.080.080.080.080.080.15SeO20.20.30.20.20.20.50. 20.20.2—BeO0.751.251.30.750.750.750.750.750.75—CeO20.21.250.20.21.50.20.20.20.2—La2O30.350.50.350.60.350.350.35 0.35 0.35 — Elastic modulus (GPa) 8378.5 808 0.3777 9788 0.18 0.17 9.2 Transmittance (%) 91.5 87.3 89.4 79.8 7575 91.2 919 1.1 88.8 Dielectric constant 6.55 6.7 6.65 6.73 6.7 6.75 6.75 6.68 6.8 6.7 Melting temperature / ℃ 1426 1440 1430 1429 1424 1426 1445 1439 1435 1426 Upper limit of crystallization temperature / ℃ 1099 1110 1105 1105 1102 1102 1112 1113 1105 1100

[0047] As shown in Tables 1-2, compared with the conventional high borosilicate glass formulation of Comparative Example 9, the glass fibers produced by the glass fiber compositions of Examples 1-5 showed no deterioration in elastic modulus, light transmittance, dielectric constant, melting temperature, and crystallization upper limit temperature (the crystallization upper limit temperature is a key parameter for the transformation of glass materials from an amorphous (disordered structure) to a crystalline (ordered structure); the lower this temperature is during glass melting, the better). Compared with the conventional high borosilicate glass formulation of Comparative Example 9, the glass fibers produced by the glass fiber compositions of Examples 6-11 showed a certain degree of improvement in light transmittance and dielectric constant.

[0048] As can be seen from Comparative Examples 1-5, when XO simultaneously contains SeO2, BeO, La2O3, CeO2, and FeO, but their mass ratio is outside the range of (0-3):(0-15):(0-15):(0-5):1 specified in this invention, all properties of the glass deteriorate to varying degrees, except for the dielectric constant, which remains unchanged. This is mainly because Se2O and Ce2O provide a large amount of free oxygen. Excessive Se2O and Ce2O not only interfere with the coordination of [AlO4] and [TiO4], but also weaken the bridging oxygen in [SiO4], destroy the compactness of the structure, reduce the elastic modulus of the glass, promote crystallization, and also cause the color of the glass to darken, losing the optimized glass color. Excessive BeO may lead to an increase in melting temperature or a decrease in fluidity. Excessive La2O3 will lead to La 3+ The accumulation effect disrupts the uniformity of the glass network structure, leading to phase separation or crystallization, forming localized non-uniform regions, and reducing the material's light transmittance and mechanical strength. Therefore, the mass ratio of FeO, SeO2, BeO, La2O3, and CeO2 should be within a reasonable range.

[0049] As can be seen from Comparative Example 6, when the MgO content is too high, the CaO content is too low, and the mass ratio of CaO to MgO is not within the range of (9-12):1 specified in this invention, the upper limit temperature of crystallization will increase significantly, the melting temperature of the glass will also increase, and the difficulty of melting the glass will increase.

[0050] As can be seen from Comparative Examples 7-8, when the content of K2O and Na2O is too low or the mass ratio is not within the range of (0.5-3.5):1 specified in this invention, the upper limit temperature of glass crystallization will also increase significantly, and the melting temperature of glass will also increase, resulting in increased difficulty in melting glass.

Claims

1. A low-boron, high-performance, alkali-free glass fiber composition, characterized in that, The composition includes the following components by mass percentage: SiO2: 52-60%, Al2O3: 11-15%, B2O3: 2-6%, CaO: 18-25%, MgO: 1-3%, Fe2O3: 0.1-0.6%, TiO2: 0.1-2.5%, F2: 0.3-0.6%, K2O: 0.05-0.75%, Na2O: 0.05-0.75%, XO: 0.1-3%; wherein XO is one or more of FeO, SeO2, BeO, La2O3 and CeO2.

2. The low-boron, high-performance, alkali-free glass fiber composition as described in claim 1, characterized in that, In XO, the mass ratio of SeO2, BeO, La2O3, CeO2 to FeO is (0-3):(0-15):(0-15):(0-5):

1.

3. The low-boron, high-performance, alkali-free glass fiber composition as described in claim 1, characterized in that, XO consists of FeO, SeO2, BeO, La2O3, and CeO2.

4. The low-boron, high-performance, alkali-free glass fiber composition as described in claim 1, characterized in that, The mass ratio of CaO to MgO is (9-12):

1.

5. The low-boron, high-performance, alkali-free glass fiber composition as described in claim 1, characterized in that, The sum of the mass percentages of K2O and Na2O is 0.4-0.8%, and the mass ratio of K2O to Na2O is (0.5-3.5):

1.

6. The low-boron, high-performance, alkali-free glass fiber composition as described in claim 1, characterized in that, The mass percentage of B2O3 is 3-4%.

7. The low-boron, high-performance, alkali-free glass fiber composition according to claim 1, characterized in that, The mass percentage of MgO is 1.9-2.3%.

8. The low-boron, high-performance, alkali-free glass fiber composition as described in claim 1, characterized in that, The raw materials used are pyrophyllite, dolomite, borocalcite, limestone, lanthanum hydroxide, beryllium silicate, selenium powder, cerium oxide, and recycled glass powder.

9. The low-boron, high-performance, alkali-free glass fiber composition as described in claim 1, characterized in that, The raw materials used are kaolin, pyrophyllite, dolomite, borocalcite, quicklime, lanthanum hydroxide, beryllium silicate, selenium powder, cerium oxide, and recycled glass powder.