Method for manufacturing glass cloth, glass cloth, glass yarn, and method for screening glass yarn

Abstract

A method for manufacturing glass cloth, glass cloth, glass yarn, and a method for selecting glass yarn. A method for manufacturing glass cloth having a thickness of 8 to 100 μm, wherein the glass yarn comprising a plurality of glass filaments is woven as warp and weft yarns, and the weft yarn has a mass per unit length of 0.5 to 30.0 tex and a density of 1.8 g / cm 3 Above and less than 2.5g / cm 3 Glass filaments having a bundle width A of not less than 99.96% when measured in a 50 m length direction, and an average bundle width of not less than the lower limit C of the 50 m length, when measured in the 50 m length direction. A (μm) = 68 × ln (x) + 112 (1) x: tex of the glass filaments C (μm) = 49.0 × ln (x) + 19.5 (2) x: tex of the glass filaments.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing glass cloth, glass cloth, glass yarn, and a method for screening glass yarn. Background Art

[0002] With the recent development of the information and communications society, data communications and / or signal processing are being performed at high speeds and at high capacity. This has led to a trend toward lower dielectric constants for printed wiring boards used in electronic devices. Consequently, many low-dielectric glass cloths have been proposed for the glass cloths that constitute printed wiring boards.

[0003] For example, the low dielectric glass cloth disclosed in Patent Document 1 achieves a low dielectric constant by adding a large amount of boron oxide (B2O3) to the glass composition of the commonly used E glass cloth and adjusting the amount of other components such as silicon dioxide (SiO2).

[0004] Furthermore, Patent Documents 2 and 3 disclose methods for controlling the width or width variation of glass filaments within specific ranges in order to provide a method for producing low-dielectric glass cloth having uniform quality and glass filaments suitable for producing low-dielectric glass cloth.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application No. 2010-508226

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2020-105683

[0009] Patent Document 3: Japanese Patent Application Laid-Open No. 2021-178764 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] The low-dielectric glass cloth described in Patent Document 1, produced using low-dielectric glass yarns, suffers from significant variations in performance and quality compared to conventionally used E-glass cloth. This variation in performance and quality also affects the quality of prepregs and laminates for printed wiring boards produced using the glass cloth.

[0012] The glass cloth manufacturing method described in Patent Document 2 has the following problem: even if the overall weaving properties and fuzz quality are significantly improved, coarse fuzz exceeding several millimeters in length may still occur, resulting from the breakage and entanglement of 1 to 10 glass filaments. Furthermore, the glass cloth manufacturing method described in Patent Document 3 has the following problem: even if the fuzz quality is improved under moderate manufacturing conditions, if the production speed is increased to ensure a stable supply to the market, coarse fuzz exceeding several millimeters in length may still occur. Currently, there is a demand to suppress the occurrence of such coarse fuzz, which can be a fatal disadvantage in printed wiring board applications.

[0013] The present invention has been developed in response to the above-mentioned problems. Specifically, the present invention aims to provide a glass cloth having low quality variation, good quality, and low dielectric constant. Furthermore, the present invention aims to provide glass filaments capable of producing such a glass cloth, a method for selecting the glass filaments, and a method for producing the glass cloth.

[0014] Solutions for solving problems

[0015] The present inventors conducted intensive research to solve the above problems and found that focusing on glass yarns having a TEX, density, and strand width distribution within specific ranges can solve the above problems, thereby completing the present invention. One embodiment of the present invention is as follows. [1]

[0017] A method for producing glass cloth having a thickness of 8 to 100 μm, wherein glass yarns comprising a plurality of glass filaments are woven as warp and weft.

[0018] As weft, use

[0019] The mass per unit length is 0.5~30.0tex,

[0020] Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 ,

[0021] Glass fibers having a bundle width A of not more than 99.96% when measured in the longitudinal direction of 50 m and an average bundle width of not less than the lower limit C shown in the following formula (2) when measured in the longitudinal direction of 50 m.

[0022] A(μm)=68×ln(x)+112…(1)

[0023] x: tex of glass fiber

[0024] C(μm)=49.0×ln(x)+19.5…(2)

[0025] x: tex of glass fiber. [2]

[0027] The method for producing glass cloth according to [1], wherein:

[0028] As weft, use

[0029] When measured in the longitudinal direction of 50 m, 98.00% or more of the glass filaments in the longitudinal direction are equal to or less than the bundle width B represented by the following formula (3).

[0030] B(μm)=75×ln(x)+80…(3)

[0031] x: tex of glass fiber. [3]

[0033] The method for producing glass cloth according to [1] or [2], wherein the twist interval length of the glass filaments is 1.8 to 4.0 cm. [4]

[0035] The method for producing glass cloth according to any one of [1] to [3], wherein the glass yarn having a silicon (Si) content of 40 to 60% by mass as silicon dioxide (SiO2) and a boron (B) content of 15 to 40% by mass as boron oxide (B2O3) is used as the weft yarn. [5]

[0037] The method for producing a glass cloth according to [4], wherein the glass yarn having a B content of 20 to 40% by mass in terms of B2O3 is used as the weft yarn. [6]

[0039] The method for producing a glass cloth according to any one of [1] to [5], wherein the glass yarn having an elastic modulus of 50 to 70 GPa is used as the weft yarn. [7]

[0041] The method for producing a glass cloth according to any one of [1] to [6], wherein the glass yarn having an elastic modulus of 50 to 63 GPa is used as the weft yarn. [8]

[0043] The method for producing a glass cloth according to any one of [1] to [7], wherein the weft is woven at a beating speed of more than 350 threads and not more than 1000 threads per minute. [9]

[0045] A glass yarn, which is the glass yarn used in the weft yarn of glass cloth,

[0046] For glass fibers,

[0047] The mass per unit length is 0.5~30.0tex,

[0048] Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 ,

[0049] When measuring in the longitudinal direction of 50 m, 99.96% or more of the strand width in the longitudinal direction is less than or equal to the strand width A represented by the following formula (1), and the average strand width when measuring in the longitudinal direction of 50 m is greater than or equal to the lower limit C represented by the following formula (2).

[0050] A(μm)=68×ln(x)+112…(1)

[0051] x: tex of glass fiber

[0052] C(μm)=49.0×ln(x)+19.5…(2)

[0053] x: tex of glass fiber.

[10]

[0055] The glass yarn according to [9], wherein

[0056] For glass fibers,

[0057] When the longitudinal direction is 50 m, 98.00% or more of the longitudinal direction is less than the bundle width B represented by the following formula (3).

[0058] B(μm)=75×ln(x)+80…(3)

[0059] x: tex of glass fiber.

[11]

[0061] The glass filament according to [9] or

[10] , wherein the twist interval length of the glass filament is 1.8 to 4.0 cm.

[12]

[0063] The glass filament according to any one of [9] to

[11] , wherein the silicon (Si) content is 40 to 60% by mass when calculated as silicon dioxide (SiO2), and the boron (B) content is 15 to 40% by mass when calculated as boron oxide (B2O3).

[13]

[0065] The glass filament according to

[12] , wherein the B content is 20 to 40% by mass in terms of B2O3.

[14]

[0067] The glass filament according to any one of [9] to

[13] , wherein the elastic modulus is 50 to 70 GPa.

[15]

[0069] The glass filament according to any one of [9] to

[14] , wherein the elastic modulus is 50 to 63 GPa.

[16]

[0071] The glass filament according to any one of [9] to

[15] , having a dielectric constant of 5.0 or less at a frequency of 10 GHz.

[17]

[0073] The glass filament according to any one of [9] to

[16] , having a dielectric loss tangent of 0.0050 or less at a frequency of 10 GHz.

[18]

[0075] The glass yarn according to any one of [9] to

[17] , which is used for weaving glass cloth for use as high-speed communication infrastructure.

[19]

[0077] A glass cloth comprising the glass fibers according to any one of [9] to

[18] .

[20]

[0079] The glass cloth according to

[19] has a dielectric constant of 5.0 or less at a frequency of 10 GHz. [twenty one]

[0081] The glass cloth according to

[19] or

[20] is used for high-speed communication infrastructure. [twenty two]

[0083] A method for screening glass fibers, which is suitable for producing glass cloth woven from glass fibers as warp and weft.

[0084] The screening method has the following steps:

[0085] As the aforementioned weft, screening

[0086] The mass per unit length is 0.5~30.0tex,

[0087] Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 ,

[0088] Glass filaments having a bundle width A of not less than 99.96% when measured in a longitudinal direction of 50 m, as represented by the following formula (1), and an average bundle width of not less than the lower limit C represented by the following formula (2) when measured in a longitudinal direction of 50 m,

[0089] A(μm)=68×ln(x)+112…(1)

[0090] x: tex of glass fiber

[0091] C(μm)=49.0×ln(x)+19.5…(2)

[0092] x: tex of glass fiber.

[0093] Effects of the Invention

[0094] According to the present invention, it is possible to provide a glass cloth having a small quality deviation, good quality, and low dielectric constant. In addition, according to the present invention, it is possible to provide glass yarns capable of producing such a glass cloth, a method for screening the glass yarns, and a method for manufacturing the glass cloth. DETAILED DESCRIPTION

[0095] An embodiment of the present invention (hereinafter referred to as “this embodiment”) will be described in detail below, but the present invention is not limited thereto and various modifications are possible without departing from the spirit and scope of the present invention.

[0096] In the present embodiment, the numerical range recorded using "~" includes the numerical values ​​before and after "~" as the lower limit and upper limit. In addition, in the present embodiment, in the numerical range recorded in stages, the upper limit or lower limit recorded in a certain numerical range can be replaced by the upper limit or lower limit of the numerical range recorded in other stages. Furthermore, in the present embodiment, the upper limit or lower limit recorded in a certain numerical range can also be replaced by the value shown in the embodiment. In addition, in the present embodiment, the term "process" includes not only independent processes, but also processes that cannot be clearly distinguished from other processes, if the function of the process is achieved, it is also included in this term.

[0097] [Glass Fiber]

[0098] The glass yarn of this embodiment is used as the weft yarn of glass cloth.

[0099] For the above-mentioned glass fibers,

[0100] The mass per unit length is 0.5~30.0tex,

[0101] Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 ,

[0102] When measured in the longitudinal direction of 50 m, 99.96% or more of the longitudinal direction is less than the bundle width A represented by the following formula (1), and the average bundle width when measured in the longitudinal direction of 50 m is greater than the lower limit C represented by the following formula (2).

[0103] A(μm)=68×ln(x)+112…(1)

[0104] x: tex of glass fiber

[0105] C(μm)=49.0×ln(x)+19.5…(2)

[0106] x: tex of glass fiber

[0107] Here, the glass yarn includes a plurality of glass filaments, and the yarn bundle width A is uniquely determined by TEX. In this specification, "tex" refers to the mass (in grams) per 1000 m and is a unit indicating the fineness (thickness) of the yarn.

[0108] Research by the present inventors has revealed that glass cloth made from low-dielectric glass filaments exhibits varying quality compared to conventional E-glass cloth, making it difficult to consistently produce high-quality glass cloth. A detailed examination of relatively low-quality glass cloth revealed that glass cloth made from glass filaments containing wide strands in the longitudinal strand width distribution of the glass filaments (particularly the weft strands) exhibited numerous coarse fuzz defects. Examples of coarse fuzz defects include defects exceeding several millimeters in length (e.g., defects exceeding 2 mm in length) caused by entanglement of 1 to 10 broken glass filaments.

[0109] This embodiment is based on the discovery that this disadvantage can be reduced by using glass yarns selected as weft yarns from the viewpoints of having a small ratio of wide strand width portions in the longitudinal direction and having a strand width distribution within a specific range uniquely determined by TEX.

[0110] That is, one aspect of the present embodiment is a method for selecting glass yarns suitable for producing glass cloth woven with the glass yarns as warp yarns and weft yarns.

[0111] The screening method has the following steps:

[0112] As weft, screening

[0113] The mass per unit length is 0.5~30.0tex,

[0114] Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 ,

[0115] Glass filaments having a bundle width A or less for 99.96% or more of the strands measured over 50 m in the longitudinal direction and an average bundle width of C or more when measured over 50 m in the longitudinal direction.

[0116] The reasons for obtaining the above-mentioned effects are not limited by theory and are speculated as follows. For glass yarns (weft yarns) that even partially include a portion with a wide bundle width, the resistance of the portion with a wide bundle width to the air or the resistance caused by interference with the weaving components is significantly increased. Therefore, from the time the weft yarn is unwound from the bobbin to the time it is ejected, there is a tendency for the oscillation or rotational movement (also called "ballooning" or "balloon") in the direction perpendicular to the conveying direction to increase. It is believed that if shear stress is applied to the glass yarn due to friction when the weft yarn passes through weaving components such as a loop guide, filament breakage is likely to occur.

[0117] Furthermore, even wefts with locally wide bundle widths are significantly affected by fluctuations in the unwinding tension during unwinding from the bobbin, or by the on / off switching of the air jet pressure used to eject the weft. Consequently, there is a tendency for tension fluctuations to increase during weft transport. Consequently, it is thought that the aforementioned weft oscillations and balloon motions during weft transport are also likely to increase.

[0118] Furthermore, the E-glass filaments used to date have a higher mass per unit length and greater strength than low-dielectric glass filaments. This allows for more stable weft handling, minimizes interference with weaving components, and limits damage during such interference. On the other hand, the lighter and weaker low-dielectric glass filaments tend to experience increased oscillation during weft handling due to tension fluctuations, making them more susceptible to interference with weaving components and significant damage when interfering. This is believed to contribute to filament breakage. These effects are believed to affect the quality of the resulting glass cloth.

[0119] In contrast, in this embodiment, by using the aforementioned glass yarns as weft yarns, even when using relatively lightweight, weak glass yarns that have undergone low dielectric constant, the degree of interference with weaving components and the resulting damage from such interference can be consistently reduced. This prevents the occurrence of coarse fuzz caused by filament breakage in the guide wire eye, resulting in a high-quality glass cloth with minimal quality variation.

[0120] (mass per unit length of glass fiber)

[0121] The mass per unit length of the glass yarn is 0.5 to 30.0 tex, preferably 0.7 to 25.0 tex, more preferably 0.9 to 25.0 tex, and even more preferably 1.0 to 22.0 tex.

[0122] When glass yarns with a mass per unit length greater than or equal to the above lower limit are used as weft yarns, the weft conveyance path can be stabilized by ensuring that the weft yarns are distributed within a specific range uniquely determined by TEX. This allows for the stable production of high-quality glass cloth.

[0123] The greater the mass per unit length of the weft conveyor track, the more stable it is. On the other hand, as the mass per unit length increases, the shear stress generated by friction with weaving components such as the ring guide increases as the glass filaments oscillate perpendicularly to the conveying direction or experience ballooning motion, potentially causing the glass filaments to break. Glass filaments with a mass per unit length below the upper limit mentioned above can suppress the breakage of the glass filaments when used as weft by ensuring that the bundle width distribution falls within a specific range uniquely determined by TEX, enabling the stable production of high-quality glass cloth.

[0124] (Density of glass fibers)

[0125] The density of glass fiber is 1.8g / cm 3 Above and less than 2.5g / cm 3 The preferred lower limit is 2.0 g / cm 3 More preferably 2.1 g / cm 3 More preferably 2.2 g / cm 3 Above, most preferably 2.25g / cm 3 The upper limit of glass density is preferably less than 2.45 g / cm 3 , more preferably 2.4g / cm 3 the following.

[0126] Even if the density is less than 2.5g / cm 3 When the bundle width distribution of glass filaments is outside the specific range uniquely determined by TEX, the glass filaments tend to have greater oscillations or balloon motions perpendicular to the conveying direction during the conveying process from unwinding from the bobbin to ejection. Therefore, it is easy to cause poor fuzzing due to interference with weaving parts. However, by setting the density to less than 2.5 g / cm 3 By ensuring that the width of the weft is distributed within a specific range uniquely determined by TEX, the weft conveying track can be stabilized, and high-quality glass cloth can be obtained stably.

[0127] If the density is 1.8g / cm 3 The density of glass fibers can be as high as 1cm 3 Calculate the density of the bulk glass.

[0128] (Distribution of bundle width of glass fibers)

[0129] The glass yarn used in the weft of the present embodiment has a bundle width A represented by the following formula (1) or less for 99.96% or more of the bundle width 50 m in the longitudinal direction when measured.

[0130] A(μm)=68×ln(x)+112…(1)

[0131] x: tex of glass fiber

[0132] For the preferred range of bundle width distribution, 99.97% or more of the length direction is less than the bundle width A, and for a more preferred range, 99.98% or more of the length direction is less than the bundle width A. Furthermore, for an even more preferred range, 99.99% or more of the length direction is less than the bundle width A, and for the most preferred range, 100% of the length direction is less than the bundle width A. The bundle width A is the width of the glass bundle uniquely determined by the mass (tex) per unit length of the glass filament. It should be noted that, in this embodiment, for the preferred range of bundle width distribution, it is preferable that 100% or less of the length direction is less than the bundle width A.

[0133] Here, it is preferred that 98.00% or more of the glass filaments in the longitudinal direction of 50 m when measured in the longitudinal direction be equal to or less than the filament bundle width B represented by the following formula (3).

[0134] B(μm)=75×ln(x)+80…(3)

[0135] x: tex of glass fiber

[0136] More preferably, 98.5% or more of the longitudinal direction is within the bundle width B or less, and even more preferably, 99.0% or more of the longitudinal direction is within the bundle width B or less. Furthermore, even more preferably, 99.5% or more of the longitudinal direction is within the bundle width B or less, and most preferably, 100% or more of the longitudinal direction is within the bundle width B or less. The bundle width B is the width of the glass fiber bundle uniquely determined by the mass per unit length (tex) of the glass fiber.

[0137] When 99.96% or more of the bundle width distribution in the longitudinal direction of the glass filaments is less than the bundle width A, when this glass filament is used as a weft, filament breakage during the weft conveyance process, from unwinding the weft from the bobbin to ejection, can be suppressed. This results in consistently high-quality glass cloth with minimal fuzzing. This is believed to be due to the fact that the proportion of the total length of the glass filaments used in the weft that is subject to air resistance during weft conveyance or resistance due to interference with weaving components is reduced. Consequently, oscillation or ballooning in a direction perpendicular to the weft conveyance direction is stably kept within a small range. As a result, damage to the glass filaments caused by interference with weaving components, particularly damage caused by friction with ring guides, is minimized. Furthermore, when 99.96% or more of the bundle width distribution in the longitudinal direction of the glass filaments is less than the bundle width A, the glass filaments constituting the glass filaments tend to be tightly bundled. Therefore, when the glass yarns interfere with the weaving components, damage to the glass yarn bundle is easily dispersed. As a result, damage to a single filament is minimized, and it is estimated that the filaments are less likely to break.

[0138] In addition, if more than 99.96% of the bundle width distribution in the longitudinal direction of the glass filaments is less than the bundle width A, the tension when unwinding the weft from the bobbin is also stably suppressed to be small. As a result, the tension fluctuation of the transported weft is maintained small. As a result, the swing or balloon movement of the weft is suppressed to be small, which is presumably a good direction for reducing the damage to the weft. If more than 99.96% of the bundle width distribution in the longitudinal direction of the glass filaments is less than the bundle width A, the occurrence of filament breakage during the transport process from unwinding from the bobbin to ejection can be suppressed, so there is a tendency to increase the weaving speed (weft beating speed, loom speed), so it is preferred. Compared with the existing technology (such as the technology described in Patent Document 3), this embodiment is easier to respond to the expectations of both suppressing the occurrence of coarse fuzz and ensuring a stable supply to the market (maintaining a high production speed).

[0139] Furthermore, since at least 99.96% of the bundle width distribution in the longitudinal direction of the glass filaments is less than or equal to the bundle width A, when these glass filaments are used as warp yarns, even if they are rubbed by the eyelet guide and the like during the process of unwinding the original yarn from the bobbin and doubling the warp yarns on the creel, problems such as fuzzing can be easily prevented. This tends to enable high-quality and stable production, making it preferable. Furthermore, using these glass filaments in the warp yarns tends to increase the warping speed, making it preferable.

[0140] The reason for adding the natural logarithm to x (the tex of the glass filaments) in equations (1) and (3) is that the larger (smaller) the tex of the glass filaments, the smaller (larger) the effect of the change in tex on the glass filament conveying path, etc. With this in mind, the present embodiment is based on the following: an upper limit value for the filament bundle width for stably obtaining the desired glass cloth quality is determined based on the size of tex or its degree, and the longitudinal direction is mostly controlled to be below this upper limit.

[0141] In this embodiment, the mass per unit length of the glass filaments is 0.5 to 30.0 tex as described above. Therefore, for example, when the mass per unit length of the glass filaments is 0.5 tex, ln(x) is approximately -0.69, and the strand width calculated from formula (1) is approximately -0.69 × 68 + 112 = approximately 65 (μm). Alternatively, for example, when the mass per unit length of the glass filaments is 30.0 tex, ln(x) is approximately 3.4, and the strand width calculated from formula (1) is approximately 3.4 × 68 + 112 = approximately 343 (μm).

[0142] The intercept value "112" in equation (1) has a technical significance of ensuring a predetermined tow width regardless of changes in tex. The above can also be explained for the intercept value "80" in equation (3).

[0143] Here, compared to equation (1), equation (3) has a smaller ratio of change and smaller intercept value. Therefore, the bundle width B obtained by equation (3) is smaller than the bundle width A obtained by equation (1). In other words, by using equation (3) in addition to equation (1), the bundle width can be adjusted based on a stricter upper limit.

[0144] (Glass fiber bundle width)

[0145] The average bundle width of the glass filaments when measured in the longitudinal direction of 50 m is greater than the lower limit C1-1 shown in the following formula (2). In addition, for the average bundle width of the glass filaments, it is preferred that the average bundle width when measured in the longitudinal direction of 50 m is greater than the lower limit C1-2 shown in the following formula (4), more preferably greater than the lower limit C1-3 shown in the following formula (5), and even more preferably greater than the lower limit C1-4 shown in the following formula (6). The lower limits C1-1 to C1-4 of the average bundle width of the glass filaments are respectively the average bundle widths of the glass filaments uniquely determined based on the mass (tex) per unit length of the glass filaments. In addition, the lower limits C1-1 to C1-4 exceed 0.

[0146] The lower limit of the average fiber bundle width is C1-1 (μm) = 49.0 × ln(x) + 19.5… (2)

[0147] The lower limit of the average fiber bundle width is C1-2 (μm) = 49.5 × ln(x) + 20.0…(4)

[0148] The lower limit of the average fiber bundle width is C1-3 (μm) = 50.0 × ln(x) + 20.5…(5)

[0149] The lower limit of the average fiber bundle width is C1-4 (μm) = 50.5 × ln(x) + 21.5…(6)

[0150] x: tex of glass fiber

[0151] When the average bundle width of the glass yarns is greater than the aforementioned lower limit, the glass yarns, when used as weft yarns, are appropriately subjected to the jet air during weft beating, thereby preventing weft missing and facilitating weaving with high productivity. Furthermore, when the average bundle width of the glass yarns is greater than the aforementioned lower limit, the weft yarns are easily ejected with a relatively stable jet pressure, thereby tending to suppress the occurrence of fuzz and weaving defects in the resulting glass cloth.

[0152] The average bundle width of the glass filaments when measured over a length of 50 m is preferably less than or equal to the upper limit C2-1 shown in the following formula (7). Furthermore, the average bundle width of the glass filaments when measured over a length of 50 m is more preferably less than or equal to the upper limit C2-2 shown in the following formula (8), further preferably less than or equal to the upper limit C2-3 shown in the following formula (9), and further preferably less than or equal to the upper limit C2-4 shown in the following formula (10). The upper limits C2-1 to C-4 of the average bundle width of the glass filaments are each the average bundle widths of the glass filaments uniquely determined based on the mass (tex) per unit length of the glass filaments.

[0153] The upper limit of the average fiber bundle width C2-1 (μm) = 49.0 × ln (x) + 50.0… (7)

[0154] The upper limit of the average fiber bundle width is C2-2 (μm) = 48.0 × ln(x) + 49.0…(8)

[0155] The upper limit of the average fiber bundle width C2-3 (μm) = 47.0 × ln (x) + 48.0… (9)

[0156] The upper limit of the average fiber bundle width is C2-4 (μm) = 46.0 × ln(x) + 47.0…(10)

[0157] x: tex of glass fiber

[0158] When the average bundle width of the glass yarn is below the aforementioned upper limit, when the glass yarn is used for the warp yarn, even if it is rubbed by the eyelet guide device during the process of unwinding the raw yarn from the bobbin and doubling the warp yarn, it is easy to prevent problems such as fuzzing. This tends to enable high-quality and stable production, which is preferred. In addition, the use of the above-mentioned glass yarn for the warp yarn tends to increase the warping speed, which is also preferred.

[0159] (Breaking strength of glass fiber)

[0160] The breaking strength of the glass yarn is preferably 0.50 to 1.0 N / tex, preferably in the range of 0.55 to 0.90 N / tex, more preferably in the range of 0.60 to 0.87 N / tex, and still more preferably in the range of 0.65 to 0.85 N / tex.

[0161] If the glass yarn has a breaking strength of 0.50 N / tex or greater, when used as weft yarn, the filaments are less likely to break or cause fuzzing, even if they come into contact with weaving components such as yarn guides and are subjected to shear stress during the yarn transport process from unwinding the weft yarn from the bobbin to ejection. Similarly, even if the ejected yarn comes into contact with weaving components such as the reed and is subjected to shear stress during its flight, the filaments are less likely to break or cause fuzzing.

[0162] If the breaking strength of glass filaments is 1.0 N / tex or less, when used as weft, the yarn swing and balloon motion during the yarn transport process from unwinding the weft from the bobbin to ejection tend to be minimized. This reduces the risk of fuzzing caused by filament breakage. This is presumably due to the softness of the glass filaments.

[0163] (Composition of glass fibers)

[0164] Glass yarn is obtained by bundling a plurality of glass filaments or twisting them as needed. In this case, glass yarn is classified as multifilament and glass filament is classified as monofilament.

[0165] The elastic modulus of the glass filaments is preferably 50 to 70 GPa, more preferably 50 to 63 GPa, and even more preferably 53 to 63 GPa. An elastic modulus of 50 GPa or greater improves the rigidity of the glass filaments, making them less susceptible to fuzzing during the manufacturing process. Furthermore, an elastic modulus of 70 GPa or less improves the brittleness of the glass filaments, making them less susceptible to fuzzing during the manufacturing process. Furthermore, an elastic modulus within the above range provides the glass filaments with appropriate flexibility, making them less susceptible to filament breakage and weaving defects when mechanical loads are applied.

[0166] (Length of twist interval of glass fibers)

[0167] The twist interval length of the glass filaments is preferably 1.8 to 4.0 cm, more preferably 1.9 to 3.8 cm, further preferably 2.0 to 3.6 cm, further preferably 2.0 to 3.4 cm, particularly preferably 2.0 to 3.2 cm, and most preferably 2.0 to 3.2 cm.

[0168] When the twist interval length of the glass filaments is below the aforementioned upper limit, wide bundle areas are less likely to form, and thus, filament breakage, fuzzing, and weaving defects are less likely to occur, which is preferable. Furthermore, even when the ratio of wide bundle areas is the same, filament breakage, fuzzing, and weaving defects are less likely to occur, which is preferable. This is presumably because the continuous length of the wide bundle areas is kept short.

[0169] When the twist interval length of the glass filaments is greater than the above lower limit, the fluffing quality of the glass filaments tends to be good, and the quality of the resulting glass cloth is improved, which is preferred. This is presumably because the twisting shear stress is reduced during the glass filament production process, thereby suppressing filament breakage during the glass filament production process.

[0170] (Composition of glass fibers)

[0171] Examples of elements constituting the glass fibers include at least one selected from the group consisting of silicon (Si), boron (B), aluminum (Al), calcium (Ca), magnesium (Mg), phosphorus (P), sodium (Na), potassium (K), titanium (Ti), zinc (Zn), iron (Fe), and fluorine (F).

[0172] The silicon (Si) content of the glass filaments, calculated as SiO2, is preferably 40-60% by mass, more preferably 45-55% by mass, further preferably 47.0-53.5% by mass, and even more preferably 48.0-52.0% by mass. Si forms the skeletal structure of the glass filaments. Therefore, a Si content of 40% or more further improves the strength of the glass filaments, and tends to further suppress breakage of the glass cloth during subsequent processes such as the production of glass cloth and the production of prepregs using the glass cloth. Furthermore, a Si content of 40% or more tends to further reduce the dielectric constant of the glass cloth. On the other hand, a Si content of 60% or less further reduces the viscosity during melting during the production of the glass filaments, tending to produce glass fibers with a more homogeneous glass composition. Consequently, the resulting glass filaments are less likely to develop areas prone to devitrification or areas where bubbles are difficult to remove, resulting in less prone to locally weak areas. Consequently, the glass cloth formed from the resulting glass filaments is less likely to break. The Si content can be adjusted according to the amount of raw materials used in the production of glass filaments.

[0173] The boron (B) content of the glass filaments is preferably 15 to 40 mass %, more preferably 17 to 30 mass %, or 20 to 40 mass %, further preferably 18 to 28 mass %, further preferably 19 to 26 mass %, further more preferably 20 to 25 mass %, and most preferably 20.5 to 24.5 mass %, calculated as B2O3.

[0174] A B content of 15% by mass or greater tends to further reduce the dielectric constant. Furthermore, a B content of 15% by mass or greater improves the brittleness resistance of the glass cloth and imparts appropriate softness or flexibility to the glass cloth, thereby reducing the tendency for fuzzing to occur when the glass filaments come into contact with weaving components such as the eyelet guide and the reed.

[0175] On the other hand, in order to maintain the strength of the glass filaments, the B content is preferably 40% by mass or less. When the B content is 40% by mass or less, the moisture absorption resistance is improved, and the stability of the surface properties of the glass filaments described below can be appropriately maintained.

[0176] In particular, when the Si content in the glass filaments is within the above-mentioned range and the B content is within the above-mentioned range, the above-mentioned effects of Si and B are likely to be synergistically exhibited, which is preferable.

[0177] The B content can be adjusted by the amount (feeding amount) of raw materials used in the production of glass filaments. It should be noted that in the production of glass filaments, if the production conditions, amounts or contents can be changed, the feeding amount of raw materials can be adjusted based on these changes.

[0178] The aluminum (Al) content of the glass filaments, calculated as Al₂O₃, is preferably 11 to 18% by mass, more preferably 11 to 17.5% by mass, and even more preferably 12 to 17.0% by mass. When the Al content is within this range, electrical properties and strength tend to be further improved. The Al content can be adjusted by adjusting the amount of raw materials used in the production of the glass filaments (feeding amount).

[0179] The calcium (Ca) content of the glass filament is preferably 5.0 to 10 mass %, more preferably 5.0 to 9.0 mass %, and further preferably 5.0 to 8.5 mass % when calculated as CaO. By having a Ca content of more than 5.0 mass %, in the manufacturing process of the glass filament, the viscosity during melting is further reduced, and there is a tendency to obtain a glass fiber of a more homogeneous glass composition. In addition, by having a Ca content of less than 10 mass %, there is a tendency to further improve the dielectric constant. The Ca content can be adjusted by the amount (charging amount) of the raw materials used in the production of the glass filament.

[0180] The phosphorus (P) content of the glass filaments, calculated as P2O4, is preferably 8.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 6.0% by mass or less. A P content exceeding 0% by mass is preferable. When the P content exceeds 0% by mass, the dielectric properties of the glass cloth tend to be further improved. Furthermore, when the P content is 8.0% by mass or less, the heat resistance of the glass cloth tends to be improved. The P content can be adjusted by adjusting the amount (feeding amount) of the raw materials used in the production of the glass filaments.

[0181] It should be noted that the above-mentioned contents can be measured using ICP emission spectrometry. Specifically, the Si content and B content can be obtained by melting the weighed glass cloth with sodium carbonate, dissolving it with dilute nitric acid to a predetermined volume, and measuring the resulting sample using ICP emission spectrometry. In addition, the Fe content can be obtained by dissolving the weighed glass cloth with an alkali dissolution method to a predetermined volume, and measuring the resulting sample using ICP emission spectrometry. Furthermore, the Al content, Ca content, P content, and Mg content can be obtained by heating and decomposing the weighed glass cloth with perchloric acid, sulfuric acid, nitric acid, and hydrogen fluoride, dissolving it with dilute nitric acid to a predetermined volume, and measuring the resulting sample using ICP emission spectrometry. It should be noted that as an ICP emission spectrometer, a PS3520VDD II manufactured by Hitachi High-Technologies Corporation can be used.

[0182] (Dielectric constant of glass fiber)

[0183] The dielectric constant of the glass filaments is preferably 5.0 or less, more preferably 4.9 or less, further preferably 4.8 or less, and particularly preferably 4.6 or less at a frequency of 10 GHz. The dielectric constant can be measured, for example, by the cavity resonance method. In this embodiment, the dielectric constant refers to the dielectric constant at a frequency of 10 GHz unless otherwise specified.

[0184] (Dielectric loss tangent of glass fiber)

[0185] The dielectric loss tangent of the glass filament is preferably 0.0050 or less, more preferably 0.0040 or less, further preferably 0.0035 or less, and particularly preferably 0.0030 or less at a frequency of 10 GHz. The dielectric loss tangent can be measured, for example, using a cavity resonance method. In this embodiment, the dielectric loss tangent refers to the dielectric loss tangent at a frequency of 10 GHz unless otherwise specified.

[0186] [Method for manufacturing glass cloth]

[0187] This embodiment is a method for producing a glass cloth having a thickness of 8 to 100 μm, which is woven using glass yarns containing a plurality of glass filaments as warp and weft yarns. The aforementioned glass yarns are used as weft yarns. That is, the method for producing the glass cloth of this embodiment includes a step of weaving the aforementioned glass yarns as weft yarns. Alternatively, the aforementioned glass yarns can be used as both weft yarns and warp yarns. Specifically, this embodiment may include:

[0188] a yarn preparation step (also referred to as a "bundle width adjustment step" in this embodiment) of preparing glass yarns having a bundle width A or less for 99.96% or more of the bundle widths measured over a length of 50 m and a bundle width C or greater for an average value of the bundle widths measured over a length of 50 m;

[0189] a weaving step of weaving the prepared glass yarn to obtain glass cloth; and

[0190] The fiber-opening process of opening the glass fibers of the glass cloth. In addition, the present embodiment may have the following features as needed:

[0191] A desizing process to reduce the amount of sizing agent attached to glass fibers of glass cloth, and / or

[0192] A surface treatment process in which glass cloth or glass yarn is treated with a silane coupling agent.

[0193] Each step of this embodiment will be described below.

[0194] [Yarn preparation process (yarn width adjustment process)]

[0195] In the yarn preparation step (bundle width adjustment step), glass yarns are prepared in which 99.96% or more of the bundle widths in the longitudinal direction, when measured over a length of 50 m, are less than or equal to the bundle width A, and the average bundle width in the longitudinal direction, when measured over a length of 50 m, is greater than or equal to the bundle width C. Specifically, in the bundle width adjustment step, if the bundle width distribution in the longitudinal direction of the glass yarn is within the above-mentioned range, the yarn is used in the subsequent weaving step; if it is outside the range, the yarn is discarded, the glass yarn itself is replaced, or the bundle width is adjusted to be within the above-mentioned range by rewinding the glass yarn. It should be noted that even in the case of glass yarns in which the bundle width distribution in the longitudinal direction is within the above-mentioned range, the bundle width can be adjusted by replacing the glass yarn itself or rewinding the glass yarn.

[0196] Alternatively, in the strand width adjustment process, feedback can be provided to the glass yarn manufacturing process to adjust the yarn manufacturing conditions. It is believed that areas where the strand width of the glass yarn is locally wide are likely to occur in areas where weak tension is applied locally during winding of the glass yarn, or in areas where the twist density is low. Therefore, by rewinding the glass yarn, etc., it is possible to adjust the strand width distribution of the glass yarn supplied to the weaving process. When feedback is provided to the glass yarn manufacturing process and the yarn manufacturing conditions are adjusted, from the same perspective, it is possible to adjust the strand width distribution by adjusting the tension during winding and twisting of the glass yarn, as well as their range of variation. When adjustment by rewinding the glass yarn is difficult, or from the perspective of production efficiency, the glass yarn itself can also be replaced.

[0197] The glass fibers prepared at this time (to adjust the fiber bundle width) have a mass per unit length of 0.5 to 30.0 tex and a density of 1.8 g / cm 3 Above and less than 2.5g / cm 3 During the yarn preparation process, the mass per unit length and / or density can be adjusted.

[0198] [Weaving process]

[0199] The weaving step is a step of weaving the prepared glass yarns to produce glass cloth. The weaving method involves weaving the weft and warp yarns to form a predetermined weave structure. Examples of glass cloth weaves include plain weave, mat weave, satin weave, and twill weave. Of these, plain weave is more preferred.

[0200] In one method, a jet loom is used to open the upper and lower openings of the warp yarns drawn in parallel, and the yarns (weft yarns) fed from the weft yarn storage device are sent out by a jet flow from a nozzle and then pass through the openings, thereby weaving.

[0201] The weaving process may include a glass yarn ejection process in which the glass yarns that will become weft yarns are unwound from bobbins and ejected from a storage device. During this ejection process, the glass yarns move in a direction different from the direction of travel, accompanied by balloon motion, and are transported while interfering with weaving components such as yarn guides. Alternatively, the weft yarns are ejected and stopped repeatedly for each length of the weft yarn, causing fluctuations in tension and interference with weaving components such as yarn guides. Therefore, for weft yarns with a high ratio of wide bundle widths, it is difficult to minimize this interference, and the resulting glass cloth is prone to fuzzing and weaving defects.

[0202] In contrast, in this embodiment, after the aforementioned strand width adjustment step, etc., glass fibers having a strand width A or less for at least 99.96% of the length (measured over a 50-meter length) and a strand width C or greater for an average strand width (measured over a 50-meter length) are used as weft fibers. This suppresses the occurrence of fuzzing and weaving defects when weaving the glass fibers (weft fibers). This improves the in-plane uniformity and batch-to-batch uniformity of the glass cloth's quality. It should be noted that the weaving method is not limited to air-jet looms; water-jet looms or shuttle looms are also acceptable.

[0203] The weft beat-up speed for the glass cloth is preferably greater than 350 threads per minute. While the quality of glass cloth generally tends to decrease as the production speed (loom speed) increases, this embodiment allows for high-quality glass cloth to be obtained even at loom speeds exceeding 350 rpm. This embodiment also allows for high-quality glass cloth to be obtained even at weft beat-up speeds of 400 threads / minute or more, 500 threads / minute or more, or 560 threads / minute or more. It should be noted that the weft beat-up speed is preferably less than 1000 threads / minute, less than 800 threads / minute, or less than 700 threads / minute.

[0204] According to this embodiment, even when the production speed of the cloth is increased to ensure a stable supply to the market, it is possible to produce a glass cloth having low quality variation, good quality, and low dielectric constant.

[0205] This is against the backdrop of strong expectations for the expansion of high-speed communication systems, represented by fifth-generation mobile communication systems, and the need for sufficient communication infrastructure, such as base stations. Against this backdrop, there is also a strong desire for improved production speed and stable supply of low-dielectric glass cloth, a component required for communication infrastructure. This embodiment addresses these expectations. Specifically, the glass cloth, and thus the glass yarn, of this embodiment is suitable for use as high-speed communication infrastructure.

[0206] It should be noted that the "high-speed communication infrastructure" refers to the infrastructure structure (foundation) for realizing high-speed communication, and includes various industrial bases, represented by base stations for high-speed communication.

[0207] The warp and weft beat-up density of the glass cloth is preferably 30 to 90 yarns / inch, more preferably 40 to 80 yarns / inch, and even more preferably 50 to 75 yarns / inch. The warp beat-up density can be controlled by adjusting the spacing between the warp yarns drawn in parallel, while the weft beat-up density can be controlled by the number of weft jets per unit time from the nozzle and the warp yarn flow rate. Since 1 inch is 25.4 mm, the beat-up density per inch can be converted to a millimeter-level beat-up density.

[0208] The thickness of the glass cloth finally obtained after the fiber opening step is 8 to 100 μm, preferably 9 to 98 μm, and more preferably 10 to 96 μm. When the thickness of the glass cloth falls within this range, a thin glass cloth with relatively high strength tends to be obtained.

[0209] The cloth mass (weight per unit area) of the glass cloth is preferably 5 to 100 g / m 2 , more preferably 6 to 98 g / m 2 , more preferably 7 to 97 g / m 2 , particularly preferably 7 to 96 g / m 2 .

[0210] [Fiber opening process]

[0211] In the fiber-opening step, the glass fibers of the glass cloth are opened. Examples of fiber-opening methods include water spraying (high-pressure water opening), an oscillating washing machine, ultrasonic water, and a mangle.

[0212] [Desizing process]

[0213] In the desizing process, the sizing agent (also referred to as "sizing agent") attached to the glass filaments of the glass cloth is reduced. As a desizing method, a method of reducing the sizing agent by heating is mentioned, for example.

[0214] [Surface treatment process]

[0215] In the surface treatment step, the glass cloth or glass yarn is surface-treated with a silane coupling agent. Examples of surface treatment methods include contacting a surface treatment agent containing a silane coupling agent with the glass cloth or glass yarn and drying the surface treatment agent. Examples of contacting the surface treatment agent with the glass cloth or glass yarn include impregnating the glass cloth or glass yarn with the surface treatment agent, applying the surface treatment agent to the glass cloth or glass yarn using a roll coater, die coater, or gravure coater, etc. Examples of drying methods for the surface treatment agent include hot air drying and drying using electromagnetic waves.

[0216] (Surface Treatment)

[0217] The glass cloth or glass yarn may be one that has been surface treated with a surface treatment agent. Examples of the surface treatment agent include silane coupling agents, which may be used in combination with water, an organic solvent, an acid, a dye, a pigment, a surfactant, and the like as needed.

[0218] Examples of the silane coupling agent include compounds represented by the following formula (11):

[0219] X(R)3-nSiY n …(11)

[0220] (In formula (11), X is an organic functional group having at least one of an amino group and an unsaturated double bond group, Y is each independently an alkoxy group, n is an integer of 1 to 3, and R is each independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.) In formula (11), X is preferably an organic functional group having at least three or more of an amino group and an unsaturated double bond group, and X is more preferably an organic functional group having at least four or more of an amino group and an unsaturated double bond group.

[0221] As the alkoxy group in the above formula (11), any form may be used, but from the viewpoint of stabilizing the treatment of the glass cloth, an alkoxy group having 5 or less carbon atoms is preferred.

[0222] Specific examples of the silane coupling agent include N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropylmethyldimethoxysilane and its hydrochloride, N-β-(N-di(vinylbenzyl)aminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-di(vinylbenzyl)aminoethyl)-N-γ-(N-vinylbenzyl)-γ-aminopropyltrimethoxysilane and its hydrochloride. Hydrochloride, N-β-(N-benzylaminoethyl)-γ-aminopropyltrimethoxysilane and its hydrochloride, N-β-(N-benzylaminoethyl)-γ-aminopropyltriethoxysilane and its hydrochloride, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane and other well-known single components, or mixtures thereof.

[0223] The molecular weight of the silane coupling agent is preferably 100 to 600, more preferably 150 to 500, and even more preferably 200 to 450. It is preferred to use two or more silane coupling agents having different molecular weights. Treating the surface of the glass filaments with two or more silane coupling agents having different molecular weights increases the density of the surface treatment agent on the surface of the glass cloth, which tends to further improve reactivity with the matrix resin.

[0224] [Glass cloth]

[0225] The glass cloth of this embodiment includes the glass yarns as weft yarns. In one embodiment, the glass cloth preferably includes the glass yarns as weft yarns and warp yarns. The method for producing the glass cloth includes at least a yarn preparation step (a yarn bundle width adjustment step) as described above.

[0226] (Dielectric constant of glass cloth)

[0227] The dielectric constant of the resulting glass cloth is preferably 5.0 or less, more preferably 4.9 or less, even more preferably 4.8 or less, and particularly preferably 4.6 or less at a frequency of 10 GHz. The dielectric constant can be measured, for example, by the cavity resonance method. It should be noted that, in this embodiment, reference to the dielectric constant refers to the dielectric constant at a frequency of 10 GHz unless otherwise specified.

[0228] (Dielectric loss tangent of glass cloth)

[0229] The dielectric loss tangent of the resulting glass cloth is preferably 0.0050 or less, more preferably 0.0040 or less, even more preferably 0.0030 or less, and particularly preferably 0.0025 or less at a frequency of 10 GHz. The dielectric loss tangent can be measured, for example, by the cavity resonance method. It should be noted that, in this embodiment, reference to the dielectric loss tangent refers to the dielectric loss tangent at a frequency of 10 GHz unless otherwise specified.

[0230] [Prepreg]

[0231] The prepreg of the present embodiment has the glass cloth obtained as described above and the matrix resin composition impregnated in the glass cloth. The prepreg with the above-mentioned glass cloth is a prepreg with a small deviation in quality and a high yield rate of the final product. In addition, if the prepreg is utilized, due to excellent dielectric properties and excellent moisture absorption resistance, a printed wiring board (PCB) that is not easily affected by the influence of the use environment (particularly under a high humidity environment, the variation of the dielectric constant is small) can also be provided.

[0232] The prepreg of this embodiment can be manufactured by conventional methods. For example, it can be manufactured by impregnating glass cloth with a varnish made by diluting a matrix resin such as epoxy resin with an organic solvent, and then using a drying oven to volatilize the organic solvent and cure the thermosetting resin to a B-stage state (semi-cured state).

[0233] Examples of the matrix resin composition include, in addition to the aforementioned epoxy resins, thermosetting resins such as bismaleimide resins, cyanate ester resins, unsaturated polyester resins, polyimide resins, BT resins, and functionalized polyphenylene ether resins; thermoplastic resins such as polyphenylene ether resins, polyetherimide resins, liquid crystal polymers (LCPs) of wholly aromatic polyesters, polybutadiene, and fluororesins; and blends thereof. From the perspective of improving dielectric properties, heat resistance, solvent resistance, and press moldability, the matrix resin composition may be a resin obtained by modifying a thermoplastic resin with a thermosetting resin.

[0234] In addition, the matrix resin composition may contain inorganic fillers such as silica and aluminum hydroxide; flame retardants such as bromine-based, phosphorus-based, and metal hydroxide-based flame retardants; other silane coupling agents; heat stabilizers; antistatic agents; ultraviolet absorbers; pigments; colorants; lubricants, etc.

[0235] [Printed wiring board]

[0236] The printed wiring board of this embodiment includes the above-mentioned prepreg. The printed wiring board of this embodiment has low quality variation and a high final product yield. Furthermore, due to its excellent dielectric properties and excellent moisture absorption resistance, it is less susceptible to the effects of the operating environment (particularly, the fluctuation of the dielectric constant is small in high humidity environments).

[0237] [Example]

[0238] The present invention will be described in more detail below using Examples and Comparative Examples. The present invention is not limited in any way by the following Examples.

[0239] [Physical properties of glass yarn and glass cloth]

[0240] The physical properties of the glass yarn and glass cloth, specifically the thickness of the glass cloth, the diameter and average diameter of the filaments constituting the glass yarn, the number of filaments, the breaking strength (tensile strength) of the glass yarn, and the beating density of the warp and weft yarns (woven density) were measured in accordance with JIS R3420.

[0241] [Electrical properties of glass cloth]

[0242] The dielectric constant and dielectric loss tangent of each glass cloth were measured in accordance with JIS R1641 / IEC 62562, which specifies methods for measuring dielectric properties in the microwave band of fine ceramic materials used as dielectric substrates primarily for microwave circuits. Specifically, glass cloth samples, sampled to the dimensions required for measurement using each resonator, were placed in a constant temperature and humidity oven at 23°C and 50% RH for at least 8 hours to adjust the humidity. The samples were then measured using a split cylindrical resonator (manufactured by EMLabo) and an impedance analyzer (manufactured by Agilent Technologies). The measurements were performed five times for each sample, and the average value was calculated. It should be noted that the thickness of each sample was measured using the converted thickness obtained by dividing the weight per unit area of ​​each glass cloth by its density. The electrical properties of the glass cloth were measured for the glass cloths obtained in Examples 1, 10, 11, and Reference Example 1.

[0243] Conversion thickness (μm) = unit area weight (g / m 2 )÷density(g / cm 3 )

[0244] [Elastic modulus]

[0245] The elastic modulus of the glass filaments was measured by the pulse echo superposition method using a glass block obtained by melting and cooling the glass filaments as a test piece.

[0246] [Composition of glass fibers]

[0247] The composition of the glass fibers was determined by ICP emission spectroscopy. Specifically, the Si and B contents were determined as follows: The weighed glass cloth was decomposed under pressure with sodium hydroxide, dissolved with dilute nitric acid, and the insoluble portion was separated by filtration. The insoluble matter was melted with sodium carbonate, dissolved with dilute nitric acid, and combined with the filtrate to a predetermined volume to obtain a sample. The resulting sample was measured by ICP emission spectroscopy to determine the Si and B contents in terms of SiO2 and B2O3, respectively.

[0248] In addition, the Al content, Ca content, Mg content and P content are measured as follows. The weighed glass cloth is decomposed by heating with perchloric acid, sulfuric acid, nitric acid and hydrogen fluoride, and then dissolved by heating with dilute aqua regia, and the insoluble part is separated by filtration. The filtrate forms a specified volume. The insoluble matter is decomposed by heating with sulfuric acid, nitric acid, hydrochloric acid and hydrogen fluoride, and then dissolved by heating with dilute aqua regia to form a specified volume. These solutions (samples) that form a specified volume are measured by ICP emission spectrometry to determine the content in the sample and convert it into an oxide value corresponding to the target metal element. It should be noted that PS3520VDDII manufactured by Hitachi High-Technologies Corporation (the same as above) was used as an ICP emission spectrometer.

[0249] [Measurement of Tow Width Distribution]

[0250] While conveying the glass filaments at a speed of 1 m / min, the strand width of the glass filaments was measured over a continuous 50 m length using an LED projection-type transmission sizer (HIGH ACCURACY CMOS MICROMETER LS-9006MR, manufactured by KEYENCE CORPORATION). Based on the strand width data obtained for each 50 m length, the percentage of strands with a specific strand width or less and the average strand width were calculated.

[0251] Tow width measurement using an LED projection-based transmissive sizer is performed under the condition of obtaining 1934 measurement values ​​per meter. If errors occur due to LED focus misalignment, etc. (indicated as -9999 values), these measurement values ​​are omitted, and the ratio of the tow width values ​​below the specified value is calculated, along with the average tow width. Furthermore, these erroneous measurement values ​​can be omitted as appropriate for this calculation.

[0252] The tension acting on the glass filaments during conveyance was measured with a tensiometer (Conrol instruments ETPB-100-C0585 manufactured by SCHMIDT) and was 0.12 to 0.18 N.

[0253] [Evaluation 1: Weaving properties (missing weft)]

[0254] In the weaving process using the air jet loom in the examples and comparative examples, the number of weaving stops was counted during weaving of 2100 m of glass cloth, and the weaving properties were evaluated according to the following evaluation criteria.

[0255] 6: Stopped 0 times.

[0256] 5: Stop 1 to 2 times.

[0257] 4: Stop 3 to 4 times.

[0258] 3: Stop 5 to 7 times.

[0259] 2: Stop 8 to 12 times.

[0260] 1: Stop more than 13 times.

[0261] [Evaluation 2: Fabric quality (coarse fuzz)]

[0262] 2000 m of glass cloth was unwound from the glass cloth rolls obtained in Examples and Comparative Examples, and the presence of fuzz and weaving defects was checked. The quality was evaluated according to the following evaluation criteria. Evaluation results of "1" and "2" were considered unacceptable.

[0263] 6: No coarse fuzz larger than 1 mm was observed.

[0264] 5: 1 to 7 coarse fluffs of 1 mm or more were confirmed, but no coarse fluffs of 2 mm or more were observed.

[0265] 4: 8 to 29 coarse fluffs of 1 mm or more were observed, but no coarse fluffs of 2 mm or more were observed.

[0266] 3: 30 or more coarse fluffs of 1 mm or more and less than 2 mm were confirmed, but no coarse fluffs of 2 mm or more were observed.

[0267] 2: 1 to 29 coarse fuzz particles of 2 mm or more were confirmed.

[0268] 1: 30 or more coarse fuzz particles of 2 mm or larger were confirmed.

[0269] [Evaluation 3: Evaluation of electrical characteristics of substrate (dielectric loss tangent)]

[0270] Using the glass cloths obtained in Examples and Comparative Examples, test pieces for measuring electrical properties were prepared under the following conditions, and the dielectric loss tangent was measured.

[0271] The glass cloths obtained in the Examples and Comparative Examples were continuously unwound and conveyed while being impregnated with a varnish. The varnish coating amount was adjusted by passing through a slit, and then dried in a 120°C drying oven to obtain prepregs. The varnish used contained 65 parts by mass of methacrylated polyphenylene ether, 35 parts by mass of triallyl isocyanurate, 10 parts by mass of a hydrogenated styrene-based thermoplastic elastomer, 25 parts by mass of a brominated flame retardant, 65 parts by mass of spherical silica, 1 part by mass of an organic peroxide, and 210 parts by mass of toluene, and was adjusted to a resin content of 73% by mass.

[0272] The obtained prepregs were stacked a predetermined number of times, and copper foil (GTS-MP foil, 18 μm thick, manufactured by Furukawa Electric Co., Ltd.) was stacked on both sides of the stacked prepregs. In this state, vacuum pressing was performed to obtain a copper-clad laminate. The copper foil was then removed from the copper-clad laminate by etching to obtain a laminate.

[0273] From the obtained laminate, a test piece of about 50 mm in length and about 1.5 mm in width was cut out in such a way that the warp yarns of the glass cloth formed the long side. The test piece was placed in an oven at 105°C ± 2°C and dried for 2 hours. The dielectric loss tangent at 10 GHz was then measured under the conditions shown below.

[0274] Standard conditions: The test piece was left to stand in a constant temperature room at 23±2°C and a relative humidity of 50±5% for 96 hours before measurement.

[0275] Measurements were performed using a network analyzer (N5230A, manufactured by Agilent Technologies) and a cavity resonator (Cavity Resornator CP series) manufactured by Kanto Denshi Applied Development Co., Ltd., in an environment of 23±2°C and 50±5% relative humidity. Each measurement was performed on five test pieces, and the average value was used as the dielectric loss tangent.

[0276] <Weaving Test 1: Glass Cloth with a Thickness of 29μm>

[0277] [Comparative Examples 1 to 4]

[0278] Glass filaments having the composition shown in the table below (average diameter of the glass filaments: 5.1 μm, number of filaments: 100) were used for the warp and weft yarns, and the air-jet loom was operated at the same speed as shown in the table below. A glass cloth with a warp density of 65 yarns / 25 mm and a weft density of 67 yarns / 25 mm was produced. The fabric was then desized by heating, opened with high-pressure water spray, and surface treated with a silane coupling agent to produce a glass cloth having a thickness of approximately 29 μm.

[0279] 2000 m of glass cloth was unwound from the glass cloth roll obtained in the comparative example, and the cloth quality was evaluated using a loom rotation speed of 350 rpm (weft beating speed of 350 yarns / min) as a standard.

[0280] A: It was confirmed that the number of coarse fluffs larger than 2 mm was reduced.

[0281] B: The number of coarse fluffs of 2 mm or more was confirmed to be about the same.

[0282] C: An increase in the number of coarse fluffs of 2 mm or more was observed.

[0283] [Table 1]

[0284]

[0285] [Examples 1 to 11, Comparative Examples 2, 4 to 8, Reference Examples 1 and 2]

[0286] A glass cloth having a thickness of 29 μm was produced in the same manner as in Comparative Example 1 except that the air jet loom was rotated at a loom speed of 600 rpm.

[0287] The breaking strength of the glass yarns used in the weaving test, the results of weaving property evaluation during weaving, the quality of the glass cloth, and the electrical properties are shown in the following table.

[0288] [Table 2]

[0289]

[0290] [Table 3]

[0291]

[0292] The manufacturing methods of Examples 1 to 11 produced glass cloths with excellent weavability and cloth quality. Among them, the glass cloths of Examples 1, 2, 3, 5, 6, 7, 8, 10, and 11, in which the proportion of wide strands in the weft yarns was small, were particularly excellent in quality.

[0293] In addition, Examples 6, 7, and 8, in which the maximum twist interval length is within the specified range, provide glass cloths of superior cloth quality compared to Example 3, in which the maximum twist interval length is relatively large and the abundance ratio of the wide bundle width portion is equivalent.

[0294] In Example 11, the ratio of wide yarn bundles was small, and coarse fuzz tended to be slightly more frequent than in Examples 1, 2, 5, 6, 7, 8, and 10. The inventors presume that this is because the elastic modulus of the cloth obtained in Example 11 was relatively high.

[0295] In Example 5, glass yarns with many wide strand width areas were used for the warp yarns, while glass yarns with fewer wide strand width areas were used for the weft yarns, resulting in a glass cloth of good cloth quality. In contrast, Example 4, which had a slightly higher proportion of wide strand width (weft width) areas than Example 5, tended to produce slightly more coarse fuzz.

[0296] In Comparative Examples 2 and 4, increasing the loom speed to 600 rpm resulted in poor-quality glass cloth with numerous coarse fuzz. Furthermore, in Comparative Examples 1 and 2, the overall narrowness of the glass filament bundles prevented sufficient flying properties, resulting in numerous missing picks and poor weaving properties. Comparative Examples 1 to 4 demonstrate a tendency for fabric quality to decline with increasing production speed.

[0297] In the production methods of Examples 1 to 11, glass cloths of excellent quality were obtained even though the loom rotation speed was 600 rpm.

[0298] Reference Examples 1 and 2 show the production of glass cloth using conventional E glass yarns. Although glass cloth having excellent weavability and quality was obtained, the electrical properties were inferior to those of the glass cloths of Examples 1 to 11.

[0299] [Examples 12 to 14, 35, 36, Comparative Examples 9 and 16]

[0300] <Weaving Test 2: Glass Cloth with a Thickness of 14μm>

[0301] Glass filaments having the composition shown in the table below (average diameter of the glass filaments: 4.0 μm, number of filaments: 50) were used for the warp and weft yarns, and a warp weave density of 95 yarns / 25 mm and a weft weave density of 95 yarns / 25 mm were produced on an air-jet loom at a loom speed of 600 rpm (weft beating speed of 600 yarns / minute). This was then desized by heating, opened with high-pressure water spray, and surface treated with a silane coupling agent to produce a glass cloth having a thickness of approximately 14 μm.

[0302] The breaking strength of the glass yarns used in the weaving test, the results of weaving property evaluation during weaving, and the quality of the glass cloth are shown in the following table.

[0303] [Table 4]

[0304]

[0305] Glass cloths excellent in weavability and cloth quality were obtained by the production methods of Examples 12 to 14, 35, and 36. On the other hand, the glass cloths obtained by the production methods of Comparative Examples 9 and 16 had many coarse fuzzes and poor quality.

[0306] [Examples 15 to 18, Comparative Example 10]

[0307] Weaving Test 3: Glass Fabric with a Thickness of 21μm

[0308] Glass filaments having the composition shown in the table below (average diameter of the glass filaments: 4.0 μm, number of filaments: 100) were used for the warp and weft yarns, and a warp weave density of 74 yarns / 25 mm and a weft weave density of 74 yarns / 25 mm were produced on an air-jet loom at a loom speed of 600 rpm (weft beating speed of 600 yarns / minute). The fabric was then desized by heating, opened with high-pressure water spray, and surface treated with a silane coupling agent to produce a glass cloth having a thickness of approximately 21 μm.

[0309] The breaking strength of the glass yarns used in the weaving test, the results of weaving property evaluation during weaving, and the quality of the glass cloth are shown in the following table.

[0310] [Table 5]

[0311]

[0312] Glass cloths excellent in weavability and cloth quality were obtained in the production methods of Examples 15 to 18. On the other hand, the glass cloth obtained in the production method of Comparative Example 10 had many coarse fuzzes and poor quality.

[0313] [Examples 19 to 24, Comparative Examples 11 and 12]

[0314] Weaving Test 4: Glass Fabric 46μm Thickness

[0315] Glass filaments having the composition shown in the table below (average filament diameter: 5.1 μm, number of filaments: 200) were used for the warp and weft yarns, and a warp weave density of 52.5 yarns / 25 mm and a weft weave density of 52.5 yarns / 25 mm were obtained using an air-jet loom at a loom speed of 600 rpm (weft beating speed: 600 yarns / minute). The fabric was then desized by heating, opened with high-pressure water spray, and surface treated with a silane coupling agent to produce a glass cloth having a thickness of approximately 46 μm.

[0316] The breaking strength of the glass yarns used in the weaving test, the results of weaving property evaluation during weaving, and the quality of the glass cloth are shown in the following table.

[0317] [Table 6]

[0318]

[0319] Glass cloths excellent in weavability and cloth quality were obtained in the production methods of Examples 19 to 24. On the other hand, the glass cloths obtained in the production methods of Comparative Examples 11 and 12 had many coarse fuzzes and poor quality.

[0320] [Examples 25 to 28, Comparative Example 13]

[0321] Weaving Test 5: Glass Cloth 73μm Thickness

[0322] Glass filaments having the composition shown in the table below (average filament diameter: 6.1 μm, filament count: 200) were used for the warp and weft yarns, and a warp weave density of 59 yarns / 25 mm and a weft weave density of 61 yarns / 25 mm were produced on an air-jet loom at a loom speed of 600 rpm (weft beating speed: 600 yarns / minute). This was followed by a desizing treatment by heating, fiber opening by high-pressure water spraying, and surface treatment with a silane coupling agent to produce a glass cloth having a thickness of approximately 73 μm.

[0323] The breaking strength of the glass yarns used in the weaving test, the results of weaving property evaluation during weaving, and the quality of the glass cloth are shown in the following table.

[0324] [Table 7]

[0325]

[0326] Glass cloths excellent in weavability and cloth quality were obtained in the production methods of Examples 25 to 28. On the other hand, the glass cloth obtained in the production method of Comparative Example 13 had many coarse fuzzes and poor quality.

[0327] [Examples 29 to 34, Comparative Examples 14 and 15]

[0328] Weaving Test 6: Glass Fabric with a Thickness of 92 μm

[0329] Glass filaments having the composition shown in the table below (average filament diameter: 6.1 μm, number of filaments: 200) were used for the warp and weft yarns, and a warp density of 60 yarns / 25 mm and a weft density of 57 yarns / 25 mm were obtained using an air-jet loom at a loom speed of 600 rpm (weft beating speed: 600 yarns / minute). This was followed by a desizing treatment by heating, fiber opening by high-pressure water spraying, and surface treatment with a silane coupling agent to produce a glass cloth having a thickness of approximately 92 μm.

[0330] The breaking strength of the glass yarns used in the weaving test, the results of weaving property evaluation during weaving, and the quality of the glass cloth are shown in the following table.

[0331] [Table 8]

[0332]

[0333] Glass cloths excellent in weavability and cloth quality were obtained by the production methods of Examples 29 to 34. On the other hand, the glass cloths obtained by the production methods of Comparative Examples 14 and 15 had many coarse fuzz formations and deteriorated in quality.

Claims

1. A method for producing glass cloth having a thickness of 8 to 100 μm, wherein the glass cloth is woven by weaving glass yarns comprising a plurality of glass filaments as warp and weft. As the weft, The mass per unit length is 0.5~30.0tex, Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 , Glass filaments having a bundle width A of not less than 99.96% when measured in a longitudinal direction of 50 m, as represented by the following formula (1), and an average bundle width of not less than the lower limit C represented by the following formula (2) when measured in a longitudinal direction of 50 m, A(μm)=68×ln(x)+112…(1) x: tex of glass fiber C(μm)=49.0×ln(x)+19.5…(2) x: tex of glass fiber.

2. The method for producing glass cloth according to claim 1, wherein: The mass per unit length of the glass yarn used as the weft is 0.7 to 25.0 tex.

3. The method for producing glass cloth according to claim 1 or 2, wherein: The mass per unit length of the glass yarn used as the weft is 1.0 to 22.0 tex.

4. The method for producing glass cloth according to claim 1 or 2, wherein: The density of the glass yarn used as the weft is 2.0 g / cm 3 Above and less than 2.45g / cm 3 .

5. The method for producing glass cloth according to claim 1 or 2, wherein: The density of the glass yarn used as the weft is 2.25 g / cm 3 Above and 2.4g / cm 3 the following.

6. The method for producing glass cloth according to claim 1 or 2, wherein: When 50 m in the longitudinal direction of the glass yarn used as the weft is measured, 99.97% or more of the longitudinal direction is equal to or less than the yarn bundle width A represented by the above formula (1).

7. The method for producing glass cloth according to claim 1 or 2, wherein: When 50 m in the longitudinal direction of the glass yarn used as the weft is measured, 99.99% or more of the longitudinal direction is equal to or less than the yarn bundle width A represented by the above formula (1).

8. The method for producing glass cloth according to claim 1 or 2, wherein: The glass yarns used as the wefts have an average yarn bundle width measured in a longitudinal direction of 50 m of 50.5×ln(x)+21.5 or more and 46.0×ln(x)+47.0 or less.

9. The method for producing glass cloth according to claim 1 or 2, wherein: The breaking strength of the glass yarn used as the weft yarn is 0.50 to 1.0 N / tex.

10. The method for producing glass cloth according to claim 1 or 2, wherein: The breaking strength of the glass yarn used as the weft yarn is 0.65 to 0.85 N / tex.

11. The method for producing glass cloth according to claim 1 or 2, wherein: The thickness of the glass cloth is 10 to 96 μm.

12. The method for producing glass cloth according to claim 1 or 2, wherein: The unit area weight of the glass cloth is 5 to 100 g / m 2 .

13. The method for producing glass cloth according to claim 1 or 2, wherein: As the weft, When measured in the longitudinal direction of 50 m, 98.00% or more of the glass filaments in the longitudinal direction are equal to or less than the bundle width B represented by the following formula (3). B(μm)=75×ln(x)+80…(3) x: tex of glass fiber.

14. The method for producing glass cloth according to claim 13, wherein: When the glass yarn used as the weft is measured in the longitudinal direction of 50 m, 98.5% or more of the longitudinal direction is equal to or less than the yarn bundle width B represented by the above formula (3).

15. The method for producing glass cloth according to claim 13, wherein: When the glass yarn used as the weft is measured in the longitudinal direction of 50 m, 99.5% or more of the longitudinal direction is equal to or less than the yarn bundle width B represented by the above formula (3).

16. The method for producing glass cloth according to claim 1 or 2, wherein: The twist interval length of the glass filaments is 1.8 to 4.0 cm.

17. The method for producing glass cloth according to claim 1 or 2, wherein: The twist interval length of the glass filaments is 2.0 to 3.2 cm.

18. The method for producing glass cloth according to claim 1 or 2, wherein: The glass yarns having a silicon (Si) content of 40 to 60% by mass as silicon dioxide (SiO 2 ) and a boron (B) content of 15 to 40% by mass as boron oxide (B 2 O 3 ) are used as the weft yarns.

19. The method for producing glass cloth according to claim 18, wherein: The glass yarn having a B content of 20 to 40% by mass in terms of B 2 O 3 is used as the weft yarn.

20. The method for producing glass cloth according to claim 1 or 2, wherein: The glass yarn having an elastic modulus of 50 to 70 GPa is used as the weft yarn.

21. The method for producing glass cloth according to claim 1 or 2, wherein: The glass yarn having an elastic modulus of 50 to 63 GPa is used as the weft yarn.

22. The method for producing glass cloth according to claim 1 or 2, wherein: The weft yarns are woven at a beating speed of more than 350 and not more than 1000 yarns per minute.

23. The method for producing glass cloth according to claim 1 or 2, wherein: The weft yarn is woven at a beating speed of 560 or more and 700 or less per minute.

24. The method for producing glass cloth according to claim 1 or 2, wherein: As the warp yarn, The mass per unit length is 0.5~30.0tex, Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 , When measured in the longitudinal direction of 50 m, 99.96% or more of the glass filaments in the longitudinal direction are equal to or less than the bundle width A represented by the following formula (1). A(μm)=68×ln(x)+112…(1) x: tex of glass fiber.

25. The method for producing glass cloth according to claim 24, wherein: The glass yarns used as the warp yarns have an average yarn bundle width of 49.0×ln(x)+50.0 or less when measured in a longitudinal direction of 50 m.

26. A glass yarn used in the weft yarn of glass cloth. For the glass yarn, The mass per unit length is 0.5~30.0tex, Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 , When measuring in the longitudinal direction of 50 m, 99.96% or more of the strand width in the longitudinal direction is less than or equal to the strand width A represented by the following formula (1), and the average strand width when measuring in the longitudinal direction of 50 m is greater than or equal to the lower limit C represented by the following formula (2). A(μm)=68×ln(x)+112…(1) x: tex of glass fiber C(μm)=49.0×ln(x)+19.5…(2) x: tex of glass fiber.

27. The glass filament according to claim 26, wherein The mass per unit length is 0.7 to 25.0 tex.

28. The glass yarn according to claim 26 or 27, wherein The mass per unit length is 1.0 to 22.0 tex.

29. The glass filament according to claim 26 or 27, wherein The density is 2.0 g / cm 3 Above and less than 2.45g / cm 3 .

30. The glass yarn according to claim 26 or 27, wherein The density is 2.25 g / cm 3 Above and 2.4g / cm 3 the following.

31. The glass yarn according to claim 26 or 27, wherein When measured over a length of 50 m in the longitudinal direction, 99.97% or more of the longitudinal direction is equal to or less than the bundle width A represented by the above formula (1).

32. The glass yarn according to claim 26 or 27, wherein When measured over a length of 50 m in the longitudinal direction, 99.99% or more of the longitudinal direction is equal to or less than the bundle width A represented by the above formula (1).

33. The glass yarn according to claim 26 or 27, wherein The average bundle width when measured in the longitudinal direction of 50 m is 50.5×ln(x)+21.5 or more and 46.0×ln(x)+47.0 or less.

34. The glass yarn according to claim 26 or 27, wherein The breaking strength of the glass fiber is 0.50-1.0 N / tex.

35. The glass yarn according to claim 26 or 27, wherein The breaking strength of the glass filament is 0.65-0.85 N / tex.

36. The glass yarn according to claim 26 or 27, wherein For the glass yarn, When the longitudinal direction is 50 m, 98.00% or more of the longitudinal direction is less than the bundle width B represented by the following formula (3). B(μm)=75×ln(x)+80…(3) x: tex of glass fiber.

37. The glass filament according to claim 36, wherein When measured over a length of 50 m in the longitudinal direction, 98.5% or more of the longitudinal direction is equal to or less than the bundle width B represented by the above formula (3).

38. The glass filament according to claim 36, wherein When measured over a length of 50 m in the longitudinal direction, 99.5% or more of the longitudinal direction is equal to or less than the bundle width B represented by the above formula (3).

39. The glass filament according to claim 26 or 27, wherein The twist interval length of the glass filaments is 1.8 to 4.0 cm.

40. The glass filament according to claim 26 or 27, wherein The twist interval length of the glass filaments is 2.0 to 3.2 cm.

41. The glass filament according to claim 26 or 27, wherein The silicon (Si) content is 40 to 60% by mass as calculated as silicon dioxide (SiO 2 ), and the boron (B) content is 15 to 40% by mass as calculated as boron oxide (B 2 O 3 ).

42. The glass filament according to claim 41, wherein The B content is 20 to 40% by mass as calculated as B2O3.

43. The glass filament according to claim 26 or 27, wherein The elastic modulus is 50~70GPa.

44. The glass filament according to claim 26 or 27, wherein The elastic modulus is 50~63GPa.

45. The glass filament according to claim 26 or 27, wherein It has a dielectric constant of 5.0 or less at a frequency of 10 GHz.

46. ​​The glass filament according to claim 26 or 27, wherein It has a dielectric constant of 4.6 or less at a frequency of 10 GHz.

47. The glass filament according to claim 26 or 27, wherein The dielectric loss tangent is less than 0.0050 at a frequency of 10 GHz.

48. The glass filament according to claim 26 or 27, wherein The dielectric loss tangent is less than 0.0035 at a frequency of 10 GHz. The glass yarn according to claim 26 or 27, which is used for weaving glass cloth for use as high-speed communication infrastructure.

50. A glass cloth comprising the glass filaments according to any one of claims 26 to 49.

51. The glass cloth according to claim 50, wherein It has a dielectric constant of 5.0 or less at a frequency of 10 GHz.

52. The glass cloth according to claim 50 or 51, wherein It has a dielectric constant of 4.6 or less at a frequency of 10 GHz.

53. The glass cloth according to claim 50 or 51, wherein The dielectric loss tangent is less than 0.0050 at a frequency of 10 GHz.

54. The glass cloth according to claim 50 or 51, wherein The dielectric loss tangent is less than 0.0030 at a frequency of 10 GHz. The glass cloth according to claim 50 or 51, which is used for high-speed communication infrastructure.

56. The glass cloth according to claim 50 or 51, wherein The thickness of the glass cloth is 8-100 μm.

57. The glass cloth according to claim 50 or 51, wherein The thickness of the glass cloth is 10 to 96 μm.

58. A method for screening glass yarns, which is suitable for producing glass cloth woven from the glass yarns as warp and weft yarns. The screening method has the following steps: As the weft, screening The mass per unit length is 0.5~30.0tex, Density is 1.8g / cm 3 Above and less than 2.5g / cm 3 , Glass filaments having a bundle width A of not less than 99.96% when measured in a longitudinal direction of 50 m, as represented by the following formula (1), and an average bundle width of not less than the lower limit C represented by the following formula (2) when measured in a longitudinal direction of 50 m, A(μm)=68×ln(x)+112…(1) x: tex of glass fiber C(μm)=49.0×ln(x)+19.5…(2) x: tex of glass fiber.

Images