Glass fiber sizing agents, glass strands, and glass fiber reinforced resins

Abstract

To provide a sizing agent for glass fibers that can improve the mechanical strength of glass fibers, a glass strand that combines excellent mechanical properties and adhesion to resin, and a glass fiber reinforced resin with superior mechanical strength. [Solution] A sizing agent for forming a surface film on glass fibers, comprising two or more silane coupling agents and a saturated polyester resin, characterized in that the saturated polyester resin is contained in an amount of 40 to 80% by mass relative to the total amount of solid components of the sizing agent.

Description

Technical Field

[0001] The present invention relates to a sizing agent for glass fibers, glass strands, and glass fiber reinforced resins.

Background Art

[0002] Roving cross made of glass fibers made of E glass or glass single end roving is known as a reinforcing material used in the production of fiber reinforced composite resins (hereinafter sometimes referred to as FRP) in which a thermoplastic resin or a thermosetting resin is reinforced with fibers. Such a glass roving cross is a material that can be introduced into the resin of FRP without uneven distribution of glass fibers and can improve the strength of the molded body, so it is widely used in FRP products that require particularly high strength.

[0003] In addition, a roving cross made of alkali-resistant glass fibers is used by being embedded in a cement-based structural member for the purpose of reinforcing a cement-based structural material and suppressing cracks. When weaving such a roving cross, the glass roving is supplied to a loom through a plurality of guides in a state where tension is applied, that is, in a state where tensile stress acts in the roving elongation direction. At this time, the greater the applied tension, the greater the amount of fluff generated from the breakage of the glass roving, leading to a deterioration in the quality of the roving cross. Furthermore, since many glass fibers are cut in a roving cross made of glass roving with a large amount of fluff generation, the tensile strength decreases, and the mechanical strength also decreases for FRP products and cement-based products using such a roving cross.

[0004] ​​​​​​​​

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-335627 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, the glass fibers disclosed in Patent Document 1 had a problem in that the resin coating had a composition specialized for adhesion to the composite base resin, resulting in low tensile strength of the glass fibers and excessive fuzzing during the weaving process. In addition, FRP using glass fibers with excessive fuzzing tended to have low mechanical strength.

[0007] The object of the present invention is to provide a sizing agent for glass fibers that can improve the mechanical strength of glass fibers, a glass strand that combines excellent mechanical properties and adhesion to resin, and a glass fiber reinforced resin with excellent mechanical strength. [Means for solving the problem]

[0008] The following describes various embodiments of sizing agents for glass fibers, glass strands, and glass fiber reinforced resins that address the above-mentioned problems.

[0009] A sizing agent according to Embodiment 1 of the present invention is a sizing agent for forming a surface coating on glass fibers, comprising two or more silane coupling agents and a saturated polyester resin, characterized in that the saturated polyester resin is contained in an amount of 40 to 80% by mass relative to the total solid component amount of the sizing agent. In this way, a sizing agent capable of imparting excellent mechanical properties and adhesion to resin to glass fibers can be obtained.

[0010] In the sizing agent of embodiment 2, it is preferable that the sizing agent contains 1 to 10% by mass of methacrylate silane and 1 to 10% by mass of epoxy silane, relative to the total amount of solid components of the sizing agent in embodiment 1. By doing so, a sizing agent capable of imparting excellent mechanical properties and adhesion to resin to glass fibers can be obtained.

[0011] In the sizing agent of Embodiment 3, it is preferable to further contain at least one selected from bisphenol A(EO) adduct, paraffin wax, and surfactant in Embodiment 1 or Embodiment 2. By doing so, a sizing agent capable of imparting excellent mechanical properties and adhesion to resin to glass fibers can be obtained.

[0012] A glass strand according to aspect 4 of the present invention is an aggregate of glass fibers containing 10% or more of ZrO2 by mass as the glass composition, and is characterized in that a dried film of any one of the sizing agents of aspects 1 to 3 is present on the surface of the glass fibers. In this way, a glass strand with excellent mechanical properties and adhesion to resin can be obtained.

[0013] In the glass strand of embodiment 5, it is preferable that the diameter of the glass fibers is 13 μm or more and 30 μm or less, as in embodiment 4. By doing so, a glass strand with excellent mechanical properties and adhesion to resin can be obtained.

[0014] In the glass strand of embodiment 6, it is preferable that the strand count is 300 tex or higher and 4800 tex or lower in embodiment 4 or embodiment 5. By doing so, a glass strand with excellent mechanical properties and adhesion to resin can be obtained.

[0015] In the glass strand of Embodiment 7, it is preferable that the ignition loss is 0.4% by mass or more and 2.0% by mass or less in any one embodiment of Embodiments 4 to 6. By doing so, a glass strand with excellent mechanical strength and adhesion to resin can be obtained.

[0016] A glass fiber reinforced resin according to embodiment 8 of the present invention is characterized by containing a glass strand from any one of embodiments 4 to 7 and a resin containing at least one selected from an unsaturated polyester resin, an epoxy resin, and a styrene-butadiene resin. In this way, a glass fiber reinforced resin with excellent mechanical strength can be obtained. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide a sizing agent for glass fibers that can improve the mechanical strength of glass fibers, a glass strand that combines excellent mechanical properties and adhesion to resin, and a glass fiber reinforced resin with excellent mechanical strength. [Modes for carrying out the invention]

[0018] The sizing agent for forming a surface coating on glass fibers according to this embodiment comprises two or more silane coupling agents and a saturated polyester resin. The reason for the above-described composition of the sizing agent is explained below. In the following explanation of the content of each component, unless otherwise specified, "%" means "mass%".

[0019] Silane coupling agents are components that improve the strength of glass fibers and their adhesion to resins. Examples of silane coupling agents include methacrylicsilane, epoxysilane, aminosilane, ureidosilane, vinylsilane, styrylsilane, mercaptosilane, acrylicsilane, and isocyanuratesilane, and two or more of these are used in combination. Among these silane coupling agents, it is preferable to include methacrylicsilane, which improves adhesion to resins, and epoxysilane, which improves the mechanical properties of glass fibers.

[0020] Methacrylicsilane is a silane coupling agent having a methacrylic group as a functional group, and is a component that improves the adhesion between glass fibers and resin. If the methacrylicsilane content is too low, it becomes difficult to obtain the effect of improving the adhesion between glass fibers and resin. Therefore, the lower limit of the methacrylicsilane content relative to the total amount of solid components of the sizing agent is preferably 1% or more, 2% or more, and especially 3% or more. On the other hand, if the methacrylicsilane content is too high, the strength of the glass fibers decreases, or the increase in strength of the glass fiber reinforced resin due to the high methacrylicsilane content is small and not economical. Therefore, the upper limit of the methacrylicsilane content is preferably 10% or less, 9% or less, and especially 8% or less.

[0021] Epoxysilane is a silane coupling agent having an epoxy group as a functional group, and is a component that improves the mechanical properties of glass fibers. If the epoxysilane content is too low, it becomes difficult to obtain the effect of improving the mechanical properties of glass fibers. Therefore, the lower limit of the epoxysilane content relative to the total amount of solid components of the sizing agent is preferably 1% or more, 2% or more, and especially 3% or more. On the other hand, if the epoxysilane content is too high, the strength of the glass fiber reinforced resin decreases. Therefore, the upper limit of the methacrylicsilane content is preferably 10% or less, 9% or less, and especially 8% or less.

[0022] Saturated polyester resin is a component that improves the strength of glass fibers and their adhesion to the resin. If the saturated polyester resin content is too low, it becomes difficult to obtain the effect of improving the strength of glass fibers and their adhesion to the resin. Therefore, the lower limit of the saturated polyester resin content relative to the total solid component amount of the sizing agent is preferably 40% or more, 45% or more, and especially 50% or more. On the other hand, if the saturated polyester resin content is too high, the film strength increases, making it difficult for the resin to penetrate between the glass fibers, and the strength of the glass fiber reinforced resin decreases. Therefore, the upper limit of the saturated polyester resin content is preferably 80% or less, 78% or less, and especially 75% or less.

[0023] In addition to the above components, the sizing agent of this embodiment may further contain at least one selected from bisphenol A (EO) adduct, paraffin wax, and surfactant.

[0024] The bisphenol A (EO) adduct is a component that softens the film. The lower limit of the content of the bisphenol A (EO) adduct relative to the total solid content of the sizing agent is not particularly limited, but for the purpose of obtaining the above effects, for example, it may contain 0.1% or more, 1% or more, 5% or more, 10% or more. On the other hand, if the content of the bisphenol A (EO) adduct is too high, the strength of the glass fiber will decrease. Therefore, the upper limit of the content of the bisphenol A (EO) adduct is preferably 35% or less, 32% or less, particularly 30% or less. The bisphenol A (EO) adduct is a compound obtained by adding ethylene oxide to bisphenol A.

[0025] Paraffin wax is a component that gives lubricity to the strands. The lower limit of the content of paraffin wax relative to the total solid content of the sizing agent is not particularly limited, but for the purpose of obtaining the above effects, for example, it may contain 0.1% or more, 1% or more, 3% or more, 5% or more. On the other hand, if the content of paraffin wax is too high, the strength of the glass fiber reinforced resin will decrease. Therefore, the upper limit of the content of paraffin wax is preferably 10% or less, 9% or less, particularly 8% or less.

[0026] The surfactant is a lubricating component during glass fiber forming. The lower limit of the content of the surfactant relative to the total solid content of the sizing agent is not particularly limited, but for the purpose of obtaining the above effects, for example, it may contain 0.1% or more, 0.5% or more, 1% or more. On the other hand, even if the content of the surfactant is too high, it is difficult to obtain the corresponding effect, so it is not economical. Therefore, the upper limit of the content of the surfactant is preferably 7% or less, 5% or less, particularly 3% or less.

[0027] While there are no particular limitations on the surfactant used, cationic surfactants, anionic surfactants, nonionic surfactants, and nonionic surfactants can be used, and cationic surfactants are particularly preferred due to their superior lubrication performance.

[0028] While there are no particular limitations on the cationic surfactant, examples include quaternary ammonium salt type cationic surfactants and amine salt type cationic surfactants, and it is preferable to use an amine salt type cationic surfactant.

[0029] In addition to the above-mentioned components, the sizing agent of this embodiment may also contain epoxy resin, urethane resin, preservatives, antistatic agents, water, etc., depending on the desired properties.

[0030] Furthermore, the sizing agent of this embodiment is prepared as an aqueous solution or aqueous dispersion with a solid component concentration of 2 to 50% by mass and applied to glass fibers. If the concentration of the solid component is below the lower limit, the flocculation of the glass strand may be insufficient. On the other hand, if the concentration of the solid component exceeds the upper limit, the components of the sizing agent may not adhere uniformly to the surface of the glass fibers.

[0031] The glass strands and glass fiber reinforced resin of this embodiment will be described below.

[0032] The glass strand of this embodiment is an aggregate of glass fibers containing 10% or more of ZrO2 by mass as its glass composition, and has a dried film of the sizing agent described above on the surface of the glass fibers.

[0033] Examples of glass fibers containing 10% or more ZrO2 by mass include glass fibers having a composition of 10-30% ZrO2, 50-70% SiO2, 0-10% CaO, 10-30% Na2O, and 0-10% TiO2.

[0034] ZrO2 is a component that improves the alkali resistance, acid resistance, and water resistance of glass. If the ZrO2 content is too low, the alkali resistance will decrease, and the required alkali resistance for glass cannot be achieved. Therefore, the lower limit of the ZrO2 content is preferably 10% or more, 11% or more, 12% or more, 13% or more, 14% or more, 15% or more, and especially 16% or more. On the other hand, if the ZrO2 content is too high, the liquidus temperature of the glass will rise, and the temperature difference between the spinning temperature and the liquidus temperature will decrease, thus reducing productivity. Therefore, the upper limit of the ZrO2 content is preferably 30% or less, 28% or less, 26% or less, 24% or less, 22% or less, 20% or less, 19% or less, 18% or less, and especially 17.9% or less.

[0035] SiO2 is a major component that forms the glass skeleton. It is also a component that improves the mechanical strength and acid resistance of glass. If the SiO2 content is too low, the mechanical strength of the glass decreases and the elastic modulus becomes low, making it difficult to obtain sufficient strength. In addition, the acid resistance of the glass decreases. Therefore, the lower limit of the SiO2 content is preferably 50% or more, 55% or more, 56% or more, 57% or more, 58% or more, 59% or more, and especially 59.5% or more. On the other hand, if the SiO2 content is too high, the viscosity of the molten glass becomes too high, making it difficult to achieve a homogeneous molten state, and as a result, it may become difficult to adjust the glass fiber diameter. Therefore, the upper limit of the SiO2 content is preferably 70% or less, 65% or less, 64% or less, 63% or less, and especially 62.7% or less.

[0036] CaO is a component that lowers the spinning temperature during glass fiber molding and improves alkali resistance. If the CaO content is too high, the strong electric field strength of Ca ions makes it easier for zircon (ZrSiO4), which is Ca in solid solution, to precipitate as the initial phase. As a result, the liquidus temperature of the glass increases, and the temperature difference between the spinning temperature and the liquidus temperature decreases, leading to a decrease in productivity. Therefore, the upper limit of the CaO content is preferably 10% or less, 9% or less, 8% or less, 7% or less, 6.5% or less, and especially less than 6.5%. The lower limit of the CaO content is not particularly limited, but in order to obtain the above effects, it may be, for example, 0.5% or more, 1% or more, 2% or more, 3% or more, 4% or more, or 5% or more.

[0037] Na2O is a component that improves the meltability and moldability of glass by reducing its viscosity. If the Na2O content is too low, the viscosity of the glass increases, and the energy required to melt the glass increases. Therefore, the lower limit of the Na2O content is preferably 10% or more, 11% or more, 12% or more, 13% or more, and especially 13.5% or more. On the other hand, if the Na2O content is too high, the initial phase in which CaO, Na2O, K2O, etc. are solid-dissolved in zircon (ZrSiO4) is more likely to precipitate. As a result, the liquidus temperature of the glass increases, and the temperature difference between the spinning temperature and the liquidus temperature decreases, leading to a decrease in productivity. Therefore, the upper limit of the Na2O content is preferably 30% or less, 25% or less, 20% or less, 19% or less, 18% or less, 17% or less, 16% or less, 15% or less, 14.5% or less, and especially 14.2% or less.

[0038] TiO2 improves the water resistance of glass and allows for lower melting temperatures, viscosity, and spinning temperatures (Tx), thus maintaining good productivity. On the other hand, if the TiO2 content is too high, alkali resistance tends to decrease, and TiO2-based devitrified crystals are more likely to form in the molten glass, which can cause nozzle clogging of the bushing during glass fiber molding. Therefore, the upper limit of the TiO2 content is preferably 10% or less, 7.5% or less, 5% or less, 4% or less, 3% or less, 2% or less, 1% or less, and especially less than 1%. The lower limit of the TiO2 content is not particularly limited, but to obtain the above effects, it may be, for example, 0.001% or more, 0.005% or more, or 0.01% or more.

[0039] Furthermore, the glass fibers of this embodiment may also contain components other than those described above, such as Y2O3, HfO2, Al2O3, K2O, MgO, P2O5, Li2O, Fe2O3, and SO3. The content of these components can be, for example, 10% or less, 5% or less, 2% or less, and especially 1% or less, respectively.

[0040] The fiber diameter of the glass fibers constituting the glass strand is preferably 13 to 30 μm. If the fiber diameter is below the lower limit, the mechanical strength of the glass fibers decreases, and consequently, the mechanical strength of the glass strand also decreases. On the other hand, if the fiber diameter exceeds the upper limit, the flexibility of the glass fibers is lost, and the glass fibers become prone to breaking.

[0041] The strand count of the glass strand is preferably between 300 and 4800 tex. If the strand count is below the lower limit, it becomes difficult to obtain the reinforcing effect of the composite base resin. On the other hand, if the strand count exceeds the upper limit, the surface area of ​​the glass strand becomes smaller, and the bonding area with the composite base resin decreases, which may reduce the strength of the resulting glass fiber reinforced resin.

[0042] The ignition loss of the glass strand is preferably 0.4 to 2.0 mass%. The ignition loss can be measured according to the method specified in JIS R 3420 (2023). If the ignition loss is below the lower limit, the glass strand may not be properly bundled, which may lead to defective products. On the other hand, if the ignition loss exceeds the upper limit, the surface of the glass strand may become sticky, and the glass fibers may break during processing.

[0043] The number of glass fibers (monofilaments) constituting the glass strand is preferably between 400 and 8000. If the number of glass fibers is less than the lower limit, the reinforcing effect of the composite base resin becomes difficult to obtain. On the other hand, if the number of glass fibers exceeds the upper limit, the resin does not penetrate the glass strand easily, and the strength of the glass fiber reinforced resin decreases.

[0044] The glass fiber reinforced resin of this embodiment contains the above-mentioned glass strands and a resin comprising at least one selected from unsaturated polyester resin, epoxy resin, and styrene-butadiene resin. The glass strand content in the glass fiber reinforced resin is preferably 5 to 80% by mass. If the glass strand content is below the lower limit, the reinforcing effect of the glass fiber reinforced resin becomes difficult to obtain. On the other hand, if the glass strand content exceeds the upper limit, the resin becomes less permeable to the glass strands, reducing the strength of the glass fiber reinforced resin.

[0045] Unsaturated polyester resin is a thermosetting resin with excellent transparency and heat resistance. Using a resin containing unsaturated polyester resin as a composite matrix is ​​preferable because it provides a glass fiber reinforced resin with excellent adhesion to the glass strand and superior mechanical strength.

[0046] Epoxy resin is a thermosetting resin with excellent chemical resistance, heat resistance, and mechanical strength. Using a resin containing epoxy resin as a composite base material is preferable because it provides a glass fiber reinforced resin with excellent adhesion to the glass strands and superior mechanical strength.

[0047] Styrene-butadiene resin is a random copolymer of styrene and butadiene. Using a resin containing styrene-butadiene resin as a composite matrix is ​​preferable because it provides a glass fiber reinforced resin with excellent adhesion to the glass strands and superior mechanical strength. [Examples]

[0048] The present invention will be described in detail below based on examples. However, the following examples are merely illustrative, and the present invention is not limited in any way.

[0049] (Preparation of sizing agent) The sizing agents for each sample in Examples 1-3 and Comparative Examples 1-3 were prepared as follows: Methacrylic silane, epoxy silane, saturated polyester resin, bisphenol A(EO) resin, amine salt type cationic surfactant, and paraffin wax were homogeneously mixed with distilled water so that their content relative to the total amount of solid components of the sizing agent was as shown in the table, thereby preparing the sizing agent.

[0050] (Preparation of glass strands) Molten glass (composition: SiO2 62%, Na2O 14%, TiO2 1%, ZrO2 17%, CaO 6% by mass) was drawn from a bushing to obtain glass fibers with a diameter of 18 μm. Next, the sizing agent was applied to the surface of the obtained glass fibers using an applicator, and approximately 1600 of these glass fibers were bundled together to form a glass strand with a count of 1200 tex. This glass strand was then wound up to produce a glass fiber winding. Subsequently, the glass fiber winding was heated and dried to form a dried film of the sizing agent on the surface of the glass fibers. The ignition loss of the obtained glass strand was 1% by mass.

[0051] (Fabrication of glass fiber reinforced resin) The glass fiber reinforced resin was prepared as follows: The glass strands were impregnated in an unsaturated polyester resin mixed with an initiator beforehand, and these glass strands were drawn into a tube with a diameter of approximately 6 mm. The tube was then heated at approximately 100°C for approximately 2 hours to perform a heat-curing treatment. After the heat-curing treatment, the hardened glass fiber reinforced resin was removed from the tube. The glass strand content in the glass fiber reinforced resin was approximately 60%.

[0052] (Tensile strength of glass strands) The tensile strength of the glass strand was measured in accordance with JIS R 3420 (2023).

[0053] (Bending strength of glass fiber reinforced resin) The bending strength of the glass fiber reinforced resin was measured in accordance with JIS K 7017 (1999) for the prepared glass fiber reinforced resin.

[0054] Table 1 below shows the results for the content of each component relative to the total amount of solid components of the sizing agent in Examples 1-3 and Comparative Examples 1-3, as well as the tensile strength of the glass strands and the flexural strength of the glass fiber reinforced resin.

[0055] [Table 1]

[0056] The glass strands having a coating formed from the sizing agents of Examples 1 to 3, and the glass fiber reinforced resins containing said glass strands, exhibited excellent properties, such as a tensile strength of 0.44 N / tex or higher for the strands and a flexural strength of 655 MPa or higher for the glass fiber reinforced resins, because the content of each component in the sizing agent was adjusted within the range of the present invention.

[0057] On the other hand, the glass strands having a coating formed from the sizing agents of Comparative Examples 1 to 3, and the glass fiber reinforced resins containing said glass strands, were inferior in each of their properties as follows, because the content of each component in the sizing agent was outside the scope of the present invention. In Comparative Example 1, which contained only methacrylic silane, i.e., one type of silane coupling agent, the tensile strength of the strand was low at 0.38 N / tex. Furthermore, in Comparative Example 2, which contained only epoxy silane, i.e., one type of silane coupling agent, the bending strength of the glass fiber reinforced resin was low at 575 MPa. In addition, in Comparative Example 3, where the saturated polyester resin content was 10% by mass, which is outside the scope of the present invention, the tensile strength of the strand was very low at 0.31 N / tex, and the bending strength of the glass fiber reinforced resin was also very low at 354 MPa.

Claims

1. A sizing agent for forming a surface coating on glass fibers, comprising two or more silane coupling agents and a saturated polyester resin, A sizing agent characterized by containing 40 to 80% by mass of the saturated polyester resin relative to the total amount of solid components of the sizing agent.

2. The sizing agent according to claim 1, comprising 1 to 10% by mass of methacrylate silane and 1 to 10% by mass of epoxy silane, based on the total amount of solid components of the sizing agent.

3. The sizing agent according to claim 1 or 2, further comprising at least one selected from bisphenol A (EO) adduct, paraffin wax, and surfactant.

4. The glass composition is ZrO in mass%. ２ A glass strand which is an aggregate of glass fibers containing 10% or more of the following: A glass strand characterized by having a dried film of the sizing agent described in claim 1 or 2 on the surface of the glass fiber.

5. The glass strand according to claim 4, wherein the diameter of the glass fiber is 13 μm or more and 30 μm or less.

6. A glass strand according to claim 4, wherein the strand count is 300 tex or more and 4800 tex or less.

7. The glass strand according to claim 4, wherein the ignition loss is 0.4% by mass or more and 2.0% by mass or less.

8. The glass strand described in claim 4, A glass fiber reinforced resin containing a resin comprising at least one selected from unsaturated polyester resin, epoxy resin, and styrene-butadiene resin.

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