A glass fiber with low expansion coefficient and its preparation method

Abstract

A low coefficient of thermal expansion glass fiber, relating to the field of glass fiber technology, comprising, by mass fraction: SiO 2 61.5%~65.5%; Al2O 3 21.5%~25.5%; B2O 3 0.1%~1%; MgO 6.5%~10%; CaO 0%~1%; Fe2O 3 0.1%~0.8%; F 0.1%~0.8%; La2O 3 1%–5%; Er2O 3 0%~0.5% and R2O 0%~0.2%; the remainder are unavoidable impurities; and the present invention also provides a method for preparing the above-mentioned glass fiber, comprising the following steps: S1. Prepare each raw material according to the formula and mix them evenly to obtain a batch; S2. Heat and melt the batch obtained in S1, and then keep it at a constant temperature to obtain a glass melt; S3. Draw, impregnate and wind the glass melt prepared in S2 to obtain glass fiber.

Description

Technical Field

[0001] This invention relates to the field of glass fiber technology, specifically to a low coefficient of thermal expansion glass fiber and its preparation method. Background Technology

[0002] With the rapid development of electronic information technology towards higher frequencies, higher speeds, and higher integration, the automotive industry's demand for lightweight and precision components is becoming increasingly urgent. Glass fiber, as a key reinforcing material and insulating substrate, directly determines the reliability and lifespan of end products. Especially in the commercialization of fifth-generation mobile communication technology (5G), the application of millimeter-wave bands places higher demands on the thermal expansion coefficient, dielectric constant, and elastic modulus of circuit board substrates.

[0003] However, the mainstream glass fiber varieties currently on the market have significant technical shortcomings in terms of overall performance:

[0004] First, traditional glass fiber has a high coefficient of thermal expansion, making it difficult to meet the application requirements of high-precision parts. Second, some existing glass fibers have high molding temperatures and unreasonable formulation ratios, which can easily lead to a decrease in their strength or elastic modulus. Third, in order to reduce the coefficient of thermal expansion while maintaining a certain low-temperature viscosity, some existing glass fiber formulations introduce a high content of boron oxide, which not only increases production costs but also pollutes equipment and the environment.

[0005] In summary, developing glass fiber compositions that combine low coefficient of thermal expansion, good elastic modulus, low molding temperature, and are friendly to equipment and the environment has become a key research focus. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a low coefficient of thermal expansion glass fiber and its preparation method, so as to solve the problem that the glass fiber in the prior art cannot simultaneously have a low coefficient of thermal expansion, good elastic modulus, low molding temperature and be friendly to equipment and environment.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A low coefficient of thermal expansion glass fiber, by mass fraction, comprises:

[0009] SiO2 61.5%~65.5%;

[0010] Al2O3 21.5%~25.5%;

[0011] B2O3 0.1%~1%;

[0012] MgO 6.5%~10%;

[0013] CaO 0%~1%;

[0014] Fe2O3 0.1%~0.8%;

[0015] F 0.1%~0.8%;

[0016] La2O 31%~5%;

[0017] Er2O3 0%~0.5% and

[0018] R2O 0%~0.2%;

[0019] The rest are unavoidable impurities.

[0020] Preferably, the content of La2O3 is 1% to 3% by mass fraction.

[0021] Preferably, the content of Er2O3 is 0.2% to 0.4% by mass fraction.

[0022] Preferably, the content of R2O is 0.1% to 0.2% by mass fraction, and R2O includes one or more of Na2O, K2O and Li2O.

[0023] Preferably, the sum of the mass percentages of B2O3 and Fe2O3 is ≤1.2% by mass fraction.

[0024] Preferably, the sum of the mass percentages of B2O3 and F is ≤1.5% by mass fraction.

[0025] Preferably, the sum of the mass percentages of La2O3 and Er2O3 is ≤3.5% by mass fraction.

[0026] This invention also provides a method for preparing glass fibers with a low coefficient of thermal expansion, comprising the following steps:

[0027] S1. Prepare each raw material according to the formula and mix them evenly to obtain the compound material;

[0028] S2. The batch obtained in S1 is heated and melted, and then kept at the temperature to clarify and obtain glass melt;

[0029] S3. Glass fibers are obtained by drawing, wetting, and winding the glass melt prepared in S2.

[0030] Preferably, in step S2, the heating and melting process adopts a gradient heating method. The heating rate is 15-20℃ / min for temperatures below 700℃ and above 1200℃, and the heating rate is ≤10℃ / min for temperatures between 700 and 1200℃. Finally, the melting is carried out at a temperature of 1550-1620℃ for 4-6 hours.

[0031] Preferably, in step S3, the drawing is carried out at 1390~1450°C, and the impregnation is performed using an epoxy-based impregnating agent.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. This invention constructs a high-bond-energy, strongly covalent three-dimensional rigid network (Si-O, Al-O bonds) using SiO2 and Al2O3, and utilizes Mg 2+ La 3+ Cations of equal field strength fill the network voids, achieving equilibrium [AlO4]. - The glass fiber is negatively charged, and the process is adjusted with trace amounts of B₂O₃ and F without compromising the rigidity of the skeleton. The content of alkali metal R₂O is strictly controlled to avoid increasing non-bridging oxygen. Through the synergistic effect of these multiple components, the coefficient of thermal expansion (α) of the glass fiber is reduced to as low as 3.0 × 10⁻⁶ in the temperature range from room temperature to 400°C. -6 With a temperature below ℃ and an elastic modulus exceeding 93 GPa, glass fiber possesses both a low coefficient of thermal expansion and excellent elastic modulus. Furthermore, it represents a breakthrough in traditional high-boron fiber preparation processes, being highly equipment- and environmentally friendly, and has broad application prospects.

[0034] 2. This invention optimizes the ratio of fluxing and clarifying components such as B2O3, F, and Fe2O3, and improves melt uniformity with the help of rare earth oxides (La2O3, Er2O3), thereby controlling the bubble rate during glass fiber forming to below 0.1 per 10 particles. This effect is significantly superior to existing technologies, meeting the production requirements of high-speed industrial glass fiber drawing, with high yield and stable performance, and solving the technical problem of prominent bubble defects in glass fiber forming.

[0035] 3. This invention utilizes La by introducing 1-5% La₂O₃ and 0-0.5% Er₂O₃, and limiting the total amount of both to ≤3.5%. 3+ The high charge, large ionic potential, and large atomic mass of Er₂O₃ strongly suppress oxygen atom vibrations, compressing the glass fiber network; while Er₂O₃ further optimizes the glass fiber network structure and inhibits structural relaxation and crystallization. The synergistic effect of these two factors significantly improves the density of the glass fiber and effectively suppresses thermal expansion deformation. Simultaneously, it enhances the thermal stability and chemical durability of the glass fiber, inhibits crystallization, synergistically stabilizes low expansion performance, and improves the overall mechanical properties and high-temperature performance of the glass fiber.

[0036] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from the understanding of those skilled in the art through study and practice of the invention. Detailed Implementation

[0037] To make the technical means, creative features, objectives, and effects of this invention clearer and easier to understand, the invention will be further described below in conjunction with specific embodiments:

[0038] The formulations of each embodiment are shown in Table 1:

[0039]

[0040] Table 1 Formulations for Examples 1-10

[0041] The specific preparation methods for each embodiment are as follows:

[0042] Example 1

[0043] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0044] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, heated to 700°C at a heating rate of 15°C / min, then heated to 1200°C / min at a heating rate of 10°C / min, and finally heated to 1550°C at a heating rate of 15°C / min for 6 hours, and then kept at the temperature for clarification to obtain molten glass.

[0045] S3. The glass melt obtained in S2 is drawn into fibers at 1390°C, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0046] Example 2

[0047] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0048] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, heated to 700°C at a heating rate of 16°C / min, then heated to 1200°C / min at a heating rate of 9°C / min, and finally heated to 1560°C at a heating rate of 16°C / min for 6 hours. The mixture is then kept at the temperature and clarified to obtain molten glass.

[0049] S3. The glass melt obtained in S2 is drawn into fibers at 1390°C, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0050] Example 3

[0051] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0052] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, first heated to 700°C at a heating rate of 17°C / min, then heated to 1200°C / min at a heating rate of 8°C / min, and finally heated to 1570°C at a heating rate of 17°C / min for 6 hours, and then kept at the temperature for clarification to obtain glass melt.

[0053] S3. The glass melt obtained in S2 is drawn into fibers at 1400℃, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0054] Example 4

[0055] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0056] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, first heated to 700°C at a heating rate of 18°C / min, then heated to 1200°C / min at a heating rate of 7°C / min, and finally heated to 1580°C at a heating rate of 18°C / min for 5 hours, and then kept at the temperature for clarification to obtain glass melt.

[0057] S3. The glass melt obtained in S2 is drawn into fibers at 1400℃, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0058] Example 5

[0059] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0060] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, heated to 700°C at a heating rate of 19°C / min, then heated to 1200°C / min at a heating rate of 6°C / min, and finally heated to 1590°C at a heating rate of 19°C / min for 5 hours, and then kept at the temperature for clarification to obtain molten glass.

[0061] S3. The glass melt obtained in S2 is drawn into fibers at 1410°C, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0062] Example 6

[0063] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0064] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, heated to 700°C at a heating rate of 20°C / min, then heated to 1200°C / min at a heating rate of 5°C / min, and finally heated to 1600°C at a heating rate of 20°C / min for 5 hours, and then kept at the temperature for clarification to obtain glass melt.

[0065] S3. The glass melt obtained in S2 is drawn into fibers at 1410°C, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0066] Example 7

[0067] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0068] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, heated to 700°C at a heating rate of 20°C / min, then heated to 1200°C / min at a heating rate of 4°C / min, and finally heated to 1610°C at a heating rate of 20°C / min for 5 hours, and then kept at the temperature for clarification to obtain glass melt.

[0069] S3. The glass melt obtained in S2 is drawn into fibers at 1420°C, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0070] Example 8

[0071] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0072] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, heated to 700°C at a heating rate of 20°C / min, then heated to 1200°C / min at a heating rate of 3°C / min, and finally heated to 1620°C at a heating rate of 20°C / min for 3 hours. The mixture is then kept at the temperature and clarified to obtain molten glass.

[0073] S3. The glass melt obtained in S2 is drawn into fibers at 1430°C, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0074] Example 9

[0075] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0076] S2. The batch obtained in S1 is placed in a high-temperature resistant crucible furnace, heated to 700°C at a heating rate of 20°C / min, then heated to 1200°C / min at a heating rate of 2°C / min, and finally heated to 1620°C at a heating rate of 20°C / min for 2 hours. The mixture is then kept at the temperature and clarified to obtain molten glass.

[0077] S3. The glass melt obtained in S2 is drawn into fibers at 1440°C, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0078] Example 10

[0079] S1. Prepare the raw materials according to the formula, and add them to the mixer to mix them thoroughly and evenly to obtain the compound material;

[0080] S2. Place the batch obtained in S1 into a high-temperature resistant crucible furnace, first heat it to 700℃ at a heating rate of 20℃ / min, then heat it to 1200℃ / min at a heating rate of 1℃ / min, and finally heat it to 1620℃ at a heating rate of 20℃ / min for 1 hour, and then hold it at the temperature to clarify it, to obtain glass melt.

[0081] S3. The glass melt obtained in S2 is drawn into fibers at 1450°C, and an epoxy sizing agent is applied during the drawing process. Finally, the fibers are wound up to obtain glass fibers.

[0082] The formulations of each embodiment are shown in Table 2:

[0083]

[0084] Table 2 Formulations of Comparative Examples 1-5

[0085] The only difference between Comparative Examples 1-5 and Example 1 is the content of each component in the formulation.

[0086] In the above embodiments and comparative examples, F refers to element F, which is provided by fluorite or aluminum fluoride; and the specific composition of R2O in Examples 1-10 is shown in Table 3:

[0087]

[0088] Table 3 Specific components of R2O in Examples 1-10

[0089] Furthermore, the crucibles in the high-temperature resistant crucible furnace used in the above embodiments and comparative examples are double crucibles, which include a melting crucible and a clarifying crucible arranged sequentially in the vertical direction, and the two crucibles are connected by a spiral channel.

[0090] Subsequently, the elastic modulus, crystallization temperature, viscosity Log3, working range, bubble rate, and coefficient of thermal expansion at room temperature to 400°C of the glass fibers prepared in Examples 1-10 and Comparative Examples 1-5 were tested.

[0091] The measurement standards for elastic modulus are GB / T 37780-2019; crystallization temperature is ASTM C-0829; viscosity Log3 is ASTM C-0965; the operating range is the difference between viscosity Log3 and crystallization temperature; bubble rate is GB / T 7962.8-2010; and expansion coefficient is GB / T 16920-2015.

[0092] The specific test results are shown in Table 4:

[0093]

[0094] Table 4 Performance test results of the glass fibers prepared in the examples and comparative examples

[0095] As can be seen from Tables 1-2 and 4, the glass fibers prepared in Examples 1-10 are significantly superior to those prepared in Comparative Examples 1-5 in terms of elastic modulus, crystallization temperature, viscosity Log3, operating range, bubble rate, and coefficient of thermal expansion from room temperature to 400°C. This indicates that the examples construct a high-bond-energy, strongly covalent three-dimensional rigid network (Si-O, Al-O bonds) using SiO2 and Al2O3, and utilize Mg... 2+ La 3+ Cations of equal field strength fill the network voids, achieving equilibrium [AlO4]. - By using negative charge and adjusting the process with trace amounts of B2O3 and F without compromising the rigidity of the skeleton, and by strictly controlling the content of alkali metal R2O, an excellent balance of network density, thermal stability and processing performance is achieved under the synergistic effect of the above-mentioned multi-components. This results in glass fiber having a low coefficient of thermal expansion, good elastic modulus, low molding temperature, and being friendly to equipment and the environment.

[0096] Furthermore, as can be seen from Tables 1-2 and 4, in the combination of La2O3+Er2O3, La 3+ Large ionic radii and high field strength can fill network voids, enhance network confinement, and suppress atomic migration, thereby increasing the crystallization temperature and reducing the coefficient of thermal expansion; while Er 3+ This enhances network rigidity and increases the elastic modulus; therefore, La 3+ and Er 3+ Appropriate coexistence can form complementary fillers, thereby comprehensively improving the performance of glass fibers (e.g., Example 4).

[0097] However, if the La2O3 content is too low and the Er2O3 content is too high, it will cause an imbalance in the gap filling, resulting in a decrease in network density, a reduction in elastic modulus, and an increase in bubble rate (e.g., Comparative Example 1).

[0098] For B2O3, since B participates in the network in the form of [BO4] tetrahedra, an appropriate amount of B2O3 can improve the stability of the network, resulting in glass fibers with a wider operating range, a low coefficient of thermal expansion, and a high elastic modulus (e.g., Examples 2, 7, 10). However, excessive B2O3 will cause B to transform into [BO3] trigonometric bodies, thereby disrupting the network continuity, reducing the bridging oxygen ratio, and leading to a decrease in crystallization temperature, an increase in the coefficient of thermal expansion, a decrease in the operating range, and a decrease in the elastic modulus (e.g., Comparative Example 2).

[0099] For MgO, adding an appropriate amount will result in a lower content of non-bridging oxygen in the glass fiber, better network rigidity, and a reduced coefficient of thermal expansion (e.g., Example 4); however, a high content of MgO will lead to a large amount of Mg. 2+ Breaking the Si-O bond causes a significant increase in the proportion of non-bridged oxygen, resulting in a sharp drop in network strength, an increase in the expansion coefficient, a reduction in the working range, and poor processability (e.g., Comparative Example 5).

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A glass fiber with a low coefficient of thermal expansion, characterized in that, In terms of quality fraction, it includes: SiO2 61.5%~65.5%; Al2O3 21.5%~25.5%; B2O3 0.1%~1%; MgO 6.5%~10%; CaO 0%~1%; Fe2O3 0.1%~0.8%; F 0.1%~0.8%； La2O 31%~5%; Er2O3 0%~0.5% and R2O 0%~0.2%; The rest are unavoidable impurities.

2. The low expansion coefficient glass fiber according to claim 1, characterized in that, The content of La2O3 is 1% to 3% by mass fraction.

3. The low expansion coefficient glass fiber according to claim 1, characterized in that, The content of Er2O3 is 0.2% to 0.4% by mass fraction.

4. The low expansion coefficient glass fiber according to claim 1, characterized in that, The content of R2O is 0.1% to 0.2% by mass fraction, and R2O includes one or more of Na2O, K2O and Li2O.

5. The low expansion coefficient glass fiber according to claim 1, characterized in that, The sum of the mass percentages of B2O3 and Fe2O3 is ≤1.2% by mass.

6. The low expansion coefficient glass fiber according to claim 1, characterized in that, The sum of the mass percentages of B2O3 and F is ≤1.5% by mass fraction.

7. The low expansion coefficient glass fiber according to claim 1, characterized in that, The sum of the mass percentages of La2O3 and Er2O3 is ≤3.5% by mass fraction.

8. A method for preparing low-expansion coefficient glass fiber according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Prepare each raw material according to the formula and mix them evenly to obtain the compound material; S2. The batch obtained in S1 is heated and melted, and then kept at the temperature to clarify and obtain glass melt; S3. Glass fibers are obtained by drawing, wetting, and winding the glass melt prepared in S2.

9. A low coefficient of thermal expansion glass fiber according to claim 8, characterized in that, In step S2, the heating and melting process adopts a gradient heating method. The heating rate is 15-20℃ / min for temperatures below 700℃ and above 1200℃, and the heating rate is ≤10℃ / min for temperatures between 700 and 1200℃. Finally, the melting is carried out at a temperature of 1550-1620℃ for 4-6 hours.

10. A low coefficient of thermal expansion glass fiber according to claim 8, characterized in that, In step S3, the drawing is carried out at 1390~1450℃, and the impregnation is carried out using an epoxy-based impregnating agent.

Images