TWI858480B - Glass cloth manufacturing method and glass cloth, glass yarn, and glass yarn screening method - Google Patents

Abstract

The present invention provides a glass cloth with less quality unevenness, good quality, and low dielectric constant.

A method for manufacturing glass cloth, which is a method for manufacturing glass cloth having a thickness of 8 to 100 μm by weaving glass yarns containing a plurality of glass filaments as warp yarns and weft yarns, wherein the weft yarns are glass yarns having a mass per unit length of 0.5 to 30.0 tex, a density of 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , and when measured in a length direction of 50 m, 99.96% or more of the length direction is less than or equal to the yarn bundle width A (unit: μm) expressed by the following formula (1): A=68×ln(x)+112 (1)

x: tex of glass yarn, and the average yarn bundle width when measured in the length direction of 50m is greater than the lower limit value C (unit: μm) shown by the following formula (2): C=49.0×ln(x)+19.5 (2)

x: tex of glass yarn.

Description

Glass cloth manufacturing method and glass cloth, glass yarn, and glass yarn screening method

The present invention relates to a method for manufacturing glass cloth, glass cloth, glass yarn, and a method for screening glass yarn.

With the development of the information communication field in recent years, data communication and/or signal processing are performed at a high speed with large capacity, and the dielectric constant of printed wiring boards used in electronic equipment has gradually become lower. Therefore, various low-dielectric glass cloths have been proposed for glass cloth constituting printed wiring boards.

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 (B ₂ O ₃ ) to the glass composition of the previously commonly used E glass cloth and adjusting the amounts of other components such as silicon dioxide (SiO ₂ ).

Furthermore, Patent Documents 2 and 3 disclose a method for providing a method for manufacturing low-dielectric glass cloth having uniform quality and glass yarn suitable for manufacturing low-dielectric glass cloth, wherein the yarn width or yarn width unevenness of the glass yarn is set within a specific range. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 2010-508226 [Patent Document 2] Japanese Patent Publication No. 2020-105683 [Patent Document 3] Japanese Patent Publication No. 2021-178764

The low-dielectric glass cloth made of low-dielectric glass yarn described in Patent Document 1 has a problem that its performance or quality varies greatly compared to the E-glass cloth that has been used up to now. There is also a problem that the uneven performance or quality of such glass cloth also affects the quality of prepregs, laminates for printed wiring boards, etc. obtained by using the glass cloth.

The manufacturing method of glass cloth described in Patent Document 2 has the following problem: even if the weavability and fluff quality are greatly improved overall, coarse fluff with a length exceeding several millimeters may be generated, for example, coarse fluff formed by cutting and twisting glass filaments in units of 1 to 10. In addition, the manufacturing method of glass cloth described in Patent Document 3 has the following problem: even if the fluff quality is improved under loose manufacturing conditions, when the production speed is increased to ensure a stable supply to the market, coarse fluff with a length exceeding several millimeters may be generated. The reality is that the generation of such coarse fluff will become a fatal disadvantage in the use of printed wiring boards, and therefore it is required to suppress the generation of such coarse fluff.

The present invention is completed in view of the above problems. That is, the purpose of the present invention is to provide a glass cloth with less uneven quality, good quality, and low dielectric. In addition, the purpose of the present invention is to provide a glass yarn that can realize such a glass cloth, a glass yarn screening method, and a glass cloth manufacturing method.

The inventors of the present invention have conducted intensive research to solve the above problems, and found that the above problems can be solved by focusing on glass yarns with TEX, density, and yarn bundle width distribution within a specific range, thereby completing the present invention. The following is an example of the present invention.

[1]

A method for manufacturing glass cloth, which is a method for manufacturing glass cloth having a thickness of 8 to 100 μm by weaving glass yarns containing a plurality of glass filaments as warp yarns and weft yarns, wherein the weft yarns are glass yarns having a mass per unit length of 0.5 to 30.0 tex, a density of 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , and when measured in a length direction of 50 m, 99.96% or more of the length direction is less than or equal to the yarn bundle width A (unit: μm) expressed by the following formula (1): A=68×ln(x)+112 (1)

x: tex of glass yarn, and the average yarn bundle width when measured in the length direction of 50m is greater than the lower limit value C (unit: μm) expressed by the following formula (2): C=49.0×ln(x)+19.5 (2)

x: tex of glass yarn.

[2]

The method for manufacturing glass cloth as described in [1], wherein the following glass yarn is used as the weft yarn, that is, when the length direction is 50m, more than 98.00% of the length direction is less than the yarn bundle width B (unit: μm) represented by the following formula (3), where formula (3) is: B=75×ln(x)+80 (3)

x: tex of glass yarn.

[3]

For the manufacturing method of glass cloth described in [1] or [2], the length of the twisting interval of the glass yarn is 1.8~4.0cm.

[4]

The method for producing glass cloth as described in any one of [1] to [3], wherein the glass yarn having a silicon (Si) content of 40-60 mass % calculated as silicon dioxide (SiO ₂ ) and a boron (B) content of 15-40 mass % calculated as boron oxide (B ₂ O ₃ ) is used as the weft yarn.

[5]

The method for producing glass cloth as described in [4], wherein the glass yarn having a B content of 20-40 mass % calculated as B ₂ O ₃ is used as the weft yarn.

[6]

A method for manufacturing glass cloth as described in 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]

A method for manufacturing glass cloth as described in 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]

A method for manufacturing glass cloth as described in any one of [1] to [7], wherein the weft yarn is woven at a weaving speed of more than 350 yarns and less than 1000 yarns per minute.

[9]

A glass yarn is a glass yarn used for weft yarn of glass cloth, wherein the mass per unit length of the glass yarn is 0.5-30.0 tex, the density is 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , and when the length direction is 50 m, 99.96% or more of the length direction is less than the yarn bundle width A (unit: μm) represented by the following formula (1), the formula (1) is: A=68×ln(x)+112 (1)

x: tex of glass yarn, and the average yarn bundle width when measured in the length direction of 50m is greater than the lower limit value C (unit: μm) shown by the following formula (2): C=49.0×ln(x)+19.5 (2)

x: tex of glass yarn.

[10]

As described in [9], regarding the glass yarn, when the length direction of the glass yarn is 50m, more than 98.00% of the length direction is less than the yarn bundle width B (unit: μm) shown by the following formula (3), formula (3) is: B=75×ln(x)+80 (3)

x: tex of glass yarn.

[11]

Such as the glass yarn described in [9] or [10], in which the twisting interval length of the glass yarn is 1.8~4.0 cm. [12] The glass yarn as described in any one of [9] to [11], wherein the silicon (Si) content is 40 to 60 mass% in terms of silicon dioxide (SiO ₂ ), and the boron (B) content is Boron oxide (B ₂ O ₃ ) conversion is 15 to 40% by mass. [13] The glass yarn described in [12], wherein the B content is 20 to 40% by mass in terms of B ₂ O ₃ . [14] The elastic coefficient of the glass yarn described in any one of [9] to [13] is 50 to 70 GPa. [15] The glass yarn as described in any one of [9] to [14], having an elastic modulus of 50 to 63 GPa or less. [16] The glass yarn as described in any one of [9] to [15], It has a dielectric constant of less than 5.0 at a frequency of 10 GHz. [17] The glass yarn as described in any one of [9] to [16], which has a dielectric dissipation factor of less than 0.0050 at a frequency of 10 GHz. [18] A glass yarn as described in any one of [9] to [17], which is used for weaving glass cloth used for high-speed communication infrastructure. [19]

A glass cloth comprising the glass yarn as described in any one of [9] to [18].

[20]

As described in [19], the glass cloth has a dielectric constant of less than 5.0 at a frequency of 10 GHz.

[twenty one]

Glass cloth as described in [19] or [20], which is used for high-speed communication infrastructure.

[twenty two]

A glass yarn screening method is suitable for producing a glass cloth woven with the glass yarn as warp yarn and weft yarn, comprising the following steps: as the above-mentioned weft yarn, the following glass yarn is screened, that is, the mass per unit length is 0.5-30.0 tex, the density is 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , and when the length direction is 50 m, the length direction of the glass yarn is 99.96 or more and the length direction of the glass yarn is less than the yarn bundle width A (unit: μm) expressed by the following formula (1), the formula (1) is: A=68×ln(x)+112 (1)

x: tex of glass yarn, and the average yarn bundle width when measured in the length direction of 50m is greater than the lower limit value C (unit: μm) shown by the following formula (2): C=49.0×ln(x)+19.5 (2)

x: tex of glass yarn.

According to the present invention, a glass cloth with less uneven quality, good quality, and low dielectric can be provided. In addition, according to the present invention, a glass yarn capable of realizing such a glass cloth, a method for screening the glass yarn, and a method for manufacturing the glass cloth can be provided.

The following describes the implementation method of the present invention (hereinafter referred to as "this implementation method") in detail, but the present invention is not limited thereto and various changes can be made within the scope of the gist thereof.

In this embodiment, the numerical range recorded using "~" includes the numerical values before and after "~" as the lower limit and upper limit. In addition, in this embodiment, in the numerical range recorded in segments, 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 this embodiment, the upper limit or lower limit recorded in a certain numerical range can also be replaced by the value shown in the embodiment. Moreover, in this embodiment, the term "step" is not only an independent step, but also included in this term as long as it can realize the function of the step when it cannot be clearly distinguished from other steps.

〔Glass yarn〕

The glass yarn of the present embodiment is a glass yarn used for the weft yarn of the glass cloth. The mass per unit length of the glass yarn is 0.5-30.0 tex, the density is 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , and when the length direction is 50 m, 99.96% or more of the length direction is less than the yarn bundle width A (unit: μm) represented by the following formula (1): A=68×ln(x)+112 (1)

x: tex of glass yarn, and the average yarn bundle width when measured in the length direction of 50m is greater than the lower limit value C (unit: μm) shown by the following formula (2): C=49.0×ln(x)+19.5 (2)

x: tex of glass yarn.

Here, the glass yarn includes a plurality of glass filaments, and the yarn bundle width A is determined unambiguously based on TEX. Furthermore, in this specification, "tex" refers to the mass (in grams) per 1000m, which is a unit indicating the yarn fineness (thickness).

The inventors of the present invention have found that the quality of glass cloth made of low-dielectric glass yarn is uneven compared to the previous E-glass cloth, and it is difficult to obtain high-quality glass cloth stably. Among them, if the glass cloth with relatively poor quality is investigated in detail, in the yarn bundle width distribution in the length direction of the glass yarn (especially the weft yarn), more coarse fuzzing defects are confirmed in the glass cloth made of glass yarn containing a portion with a wider yarn bundle width. For example, coarse fuzzing defects include defects with a length exceeding several mm (for example, defects with a length exceeding 2 mm) formed by cutting and winding glass single filaments in units of 1 to 10.

This embodiment is based on the following knowledge: by using glass yarns selected based on the viewpoints that the ratio of the portion with a wider yarn bundle width in the length direction is small and the distribution of the yarn bundle width is within a specific range determined unambiguously based on TEX as weft yarns, the defects can be reduced.

That is, one form of the present embodiment is a method for selecting glass yarns, which is suitable for producing glass cloth woven with glass yarns as warp yarns and weft yarns, and comprises the following steps: As weft yarns, the following glass yarns are selected, that is, the mass per unit length is 0.5 to 30.0 tex, the density is 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , when measured in the length direction of 50 m, more than 99.96% of the length direction is less than the yarn bundle width A, and the average yarn bundle width when measured in the length direction of 50 m is greater than the lower limit C.

The reason for the above effect is not theoretically limited, but it is speculated as follows. The glass yarn (weft yarn) partially includes a portion with a wider yarn bundle width, and the resistance of the wider yarn bundle width portion against the air resistance or the resistance caused by interference with the weaving machine mechanism becomes significantly larger. Therefore, there is a tendency that the vibration or swirling motion (also called "ballooning motion" or "balloon motion") in the vertical direction relative to the conveying direction becomes larger during the period from unwinding the weft yarn from the bobbin to ejecting it. It is believed that when the weft yarn passes through the loop guide and other weaving machine components, shear stress is applied to the glass yarn, which easily causes the filament to break.

In addition, the weft yarns that partially include a wider portion of the yarn bundle have the following tendency: they are greatly affected by the change of the unwinding tension when unwinding from the bobbin or the on/off of the jet pressure for ejecting the weft yarns, and the tension change of the weft yarns during the conveyance process becomes larger. Therefore, it is believed that the vibration or balloon movement of the weft yarns during the conveyance process is easy to become larger.

Furthermore, the E-glass glass yarn used so far has a larger mass per unit length and is stronger than the low-dielectric glass yarn. Therefore, the weft yarn is more stable when transported, and the degree of interference with the weaving machine components is also smaller, and the damage caused by interference is also limited. On the other hand, in the lighter and weaker low-dielectric glass yarn, there is a tendency for the weft yarn to vibrate more due to tension changes during transportation, which is easy to interfere with the weaving machine components, and it is also easy to suffer greater damage when interfering with the weaving machine components. Therefore, it is believed that it is easy to promote the occurrence of long yarn cutting. It is believed that these influences are presented as the quality of the woven glass cloth.

In contrast, in this embodiment, by using the above-mentioned glass yarn as the weft yarn, even when using low-dielectric, relatively light and weak glass yarn, the interference with the weaving machine components or the damage caused by the interference can be stably reduced. In this way, the generation of coarse fuzz caused by the cutting of the long filaments on the yarn path can be suppressed, and a glass cloth with good quality and less uneven quality can be obtained.

(Mass of glass yarn per unit length) The mass of glass yarn per unit length is 0.5 to 30.0 tex. It is 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.

As long as the mass per unit length of the glass yarn is above the above lower limit, the distribution of the yarn bundle width can be set within a specific range determined without difference based on TEX, so that the conveying track of the weft yarn when the glass yarn is used as the weft yarn can be stabilized. In this way, high-quality glass cloth can be stably obtained.

The greater the mass per unit length of the weft yarn, the more stable the conveying track of the weft yarn. On the other hand, if the mass per unit length increases, the shear stress generated by the friction with the weaving machine components such as the ring wire guide and the vibration or balloon movement of the glass yarn in the vertical direction relative to the conveying direction is likely to increase, and therefore, there is a tendency for the glass filaments to be easily cut. As long as the mass per unit length of the glass yarn is below the above upper limit, the distribution of the yarn bundle width can be set to a specific range determined without difference based on TEX, and the cutting of the glass filaments when using the glass yarn as a weft yarn can be suppressed, thereby stably obtaining high-quality glass cloth.

(Density of glass yarn) The density of glass yarn is 1.8 g/cm ³ or more and less than 2.5 g/cm ^3. The lower limit is preferably 2.0 g/cm ³ or more, more preferably 2.1 g/cm ³ or more, further preferably 2.2 g/cm ³ or more, and most preferably 2.25 g/cm ³ or more. The upper limit of glass density is preferably less than 2.45 g/cm ³ , more preferably 2.4/cm ³ or less.

Even if the density of glass yarn is less than 2.5 g/ ^cm3 , if the distribution of yarn bundle width is outside the specific range determined without difference based on TEX, the vibration or balloon movement in the vertical direction relative to the conveying direction during the conveying process from unwinding the glass yarn from the bobbin to ejecting it is easy to become large. Therefore, it is easy to cause fuzzing due to interference with the weaving machine mechanism. However, by setting the density of glass yarn to less than 2.5 g/ ^cm3 and setting the distribution of yarn bundle width to the specific range determined without difference based on TEX, the conveying track of the weft yarn can be stabilized, thereby stably obtaining high-quality glass cloth.

If the glass yarn has a density of 1.8 g/ ^cm3 or ^more , the conveying track of the weft yarn can be stabilized when the glass yarn is used as the weft yarn. The density of the glass yarn can be calculated as the density of a 1 cm3 block of glass.

(Distribution of yarn bundle width of glass yarn)

When the glass yarn used for weft yarn of this embodiment is measured in the length direction of 50m, more than 99.96% of the length direction is less than the yarn bundle width A (unit: μm) shown by the following formula (1), formula (1) is: A=68×ln(x)+112 (1)

x: tex of glass yarn.

The preferred range of yarn bundle width distribution is that 99.97% or more of the length direction is less than the yarn bundle width A, and the more preferred range is that 99.98% or more of the length direction is less than the yarn bundle width A. Moreover, the further preferred range is that 99.99% or more of the length direction is less than the yarn bundle width A, and the best range is that 100% of the length direction is less than the yarn bundle width A. The yarn bundle width A is the width of the glass yarn bundle determined without difference according to the mass (tex) per unit length of the glass yarn. Furthermore, in this embodiment, the preferred range of yarn bundle width distribution can be that less than 100% of the length direction is less than the yarn bundle width A.

Here, it is preferred that when the glass yarn is measured in the length direction of 50m, more than 98.00% of the length direction is less than the yarn width B (unit: μm) shown by the following formula (3), where formula (3) is: B=75×ln(x)+80 (3)

x: tex of glass yarn.

It is more preferred that 98.5% or more of the length direction is less than or equal to the yarn bundle width B, and it is further preferred that 99.0% or more of the length direction is less than or equal to the yarn bundle width B. Furthermore, it is further preferred that 99.5% or more of the length direction is less than or equal to the yarn bundle width B, and it is most preferred that 100% or more of the length direction is less than or equal to the yarn bundle width B. The yarn bundle width B is the width of the glass yarn bundle that is unambiguously defined based on the mass (tex) per unit length of the glass yarn.

By making the yarn bundle width distribution of the glass yarn in the length direction 99.96% or more below the yarn bundle width A, it is possible to suppress the occurrence of filament cuts during the conveying process from unwinding the weft yarn from the bobbin to blowing it out when the glass yarn is used as weft yarn. In this way, high-quality glass cloth with fewer fuzzing defects can be obtained stably. This is considered to be the following. That is, the ratio of the portion of the glass yarn used for weft yarn that is subjected to resistance against air during the conveying process of the weft yarn or resistance caused by interference with the weaving machine components becomes smaller. Therefore, the vibration or balloon movement in the straight direction relative to the conveying direction of the weft yarn is stably maintained within a small range. It is speculated that the damage to the glass yarn caused by interference with the weaving machine components, especially the damage caused by friction with the ring wire guide, can be suppressed to a smaller extent. In addition, if more than 99.96% of the yarn width distribution in the length direction of the glass yarn is less than the yarn bundle width A, there is a tendency for the glass filaments constituting the glass yarn to be tightly bundled. Therefore, when the glass yarn interferes with the weaving machine components, the damage acting on the glass yarn bundle is easily dispersed. It is speculated that the result is that the damage to a single filament can be suppressed to a smaller extent, so the filament is not easily cut.

Furthermore, if more than 99.96% of the bundle width distribution of the glass yarn in the length direction is less than the bundle width A, the unwinding tension of the weft yarn when it is unwound from the bobbin can be stably suppressed to be smaller. In this way, the tension variation of the weft yarn to be transported is maintained smaller. It is speculated that this will work in a good direction, that is, the vibration of the weft yarn or the movement of the balloon can be suppressed to be smaller, and the damage to the weft yarn is reduced. If 99.96% or more of the bundle width distribution of the glass yarn in the length direction is less than the bundle width A, the occurrence of filament cuts in the conveying process from unwinding from the bobbin to ejecting it can be suppressed, and therefore, there is a tendency to increase the weaving speed (weft yarn weaving speed, weaving machine rotation speed), which is preferred. Compared with the previous technology (for example, the technology described in Patent Document 3), this embodiment is more responsive to the expectations from the perspective of both suppressing the occurrence of coarse fuzz and ensuring a stable supply to the market (maintaining a higher production speed).

Furthermore, since 99.96% or more of the yarn bundle width distribution in the longitudinal direction of the glass yarn is less than the yarn bundle width A, when the glass yarn is used for warp yarn, even when the glass yarn rubs against the yarn guide during the process of unwinding the original yarn from the bobbin and merging the warp yarn using a creel, it is easy to prevent the occurrence of defects such as fuzz. Therefore, there is a tendency to be able to produce stably with good quality, which is preferred. Moreover, by using the above-mentioned glass yarn for warp yarn, there is a tendency to increase the warping speed, which is preferred.

The reason why the natural logarithm is added to x (tex of the glass yarn) in equations (1) and (3) is that the larger (smaller) the tex of the glass yarn becomes, the smaller (larger) the influence on the conveying track of the glass yarn relative to the change in the tex becomes. With this in mind, the present embodiment determines the upper limit of the yarn bundle width for stably obtaining the desired glass cloth quality based on the size of the tex or its degree, and is completed by making most of the length direction fall below the upper limit.

In the present embodiment, the mass per unit length of the glass yarn is 0.5 to 30.0 tex as described above. Therefore, for example, when the mass per unit length of the glass yarn is 0.5 tex, ln(x) is about -0.69, and therefore, according to formula (1), the yarn bundle width is calculated to be about -0.69×68+112=about 65 (μm). Also, for example, when the mass per unit length of the glass yarn is 30.0 tex, ln(x) is about 3.4, and therefore, according to formula (1), the yarn bundle width is calculated to be about 3.4×68+112=about 343 (μm). The value "112" as the intercept in formula (1) has the following technical meaning, that is, regardless of how tex changes, the specified yarn bundle width is ensured. The above technical meaning can also be expressed in the same way for the value "80" as the intercept in formula (3).

Here, in formula (3), not only is the ratio of change smaller than in formula (1), but the intercept value is also smaller. Therefore, the yarn bundle width B obtained in formula (3) becomes smaller than the yarn bundle width A obtained in formula (1). That is, by using formula (3) in addition to formula (1), the yarn bundle width can be adjusted based on a stricter upper limit.

(Glass yarn bundle width)

The average yarn bundle width of the glass yarn when measured in the length direction of 50 m is greater than the lower limit value C1-1 (unit: μm) shown in the following formula (2). In addition, regarding the average yarn bundle width of the glass yarn, the average yarn bundle width when measured in the length direction of 50 m is preferably greater than the lower limit value C1-2 (unit: μm) shown in the following formula (4), more preferably greater than the lower limit value C1-3 (unit: μm) shown in the following formula (5), and further preferably greater than the lower limit value C1-4 (unit: μm) shown in the following formula (6). The lower limits C1-1 to C1-4 of the average yarn bundle width of the glass yarn are respectively the average yarn bundle widths of the glass yarn determined without difference according to the mass (tex) per unit length of the glass yarn. Furthermore, the lower limit values C1-1~C1-4 exceed 0.

The lower limit of the average yarn width is C1-1=49.0×ln(x)+19.5 (2)

The lower limit of the average yarn width is C1-2=49.5×ln(x)+20.0 (4)

The lower limit of the average yarn width is C1-3=50.0×ln(x)+20.5 (5)

The lower limit of the average yarn bundle width is C1-4=50.5×ln(x)+21.5 (6)

x: glass yarn tex

When the average yarn bundle width of the glass yarn is greater than the above lower limit, the glass yarn is appropriately subjected to the ejected air when the weft yarn is woven, so that it is not easy to produce the weft yarn short pick, etc., and it is easy to weave with good productivity. In addition, when the average yarn bundle width of the glass yarn is greater than the above lower limit, there is a tendency that the weft yarn is easy to fly out with a relatively stable ejection pressure, so that the generation of fuzz or weaving defects in the obtained glass cloth can be suppressed.

The average yarn bundle width of the glass yarn when measured in the length direction of 50m is preferably less than the upper limit value C2-1 (unit: μm) shown in the following formula (7). In addition, regarding the average yarn bundle width of the glass yarn, the average yarn bundle width when measured in the length direction of 50m is more preferably less than the upper limit value C2-2 (unit: μm) shown in the following formula (8), and further preferably less than the upper limit value C2-3 (unit: μm) shown in the following formula (9), and further preferably less than the upper limit value C2-4 (unit: μm) shown in the formula (10). The upper limits C2-1 to C-4 of the average yarn bundle width of the glass yarn are respectively the average yarn bundle widths of the glass yarn determined without difference according to the mass (tex) per unit length of the glass yarn.

The upper limit of the average yarn width is C2-1=49.0×ln(x)+50.0 (7)

The upper limit of the average yarn bundle width is C2-2=48.0×ln(x)+49.0 (8)

The upper limit of the average yarn width is C2-3=47.0×ln(x)+48.0 (9)

The upper limit of the average yarn bundle width is C2-4=46.0×ln(x)+47.0 (10)

x: glass yarn tex

When the glass yarn is used as a warp yarn, the average yarn bundle width of the glass yarn is below the upper limit, and when the glass yarn is used as a warp yarn, even if the glass yarn rubs against the yarn guide and the like during the process of unwinding the original yarn from the bobbin and merging the warp yarn using the yarn frame, it is easy to prevent the occurrence of bad conditions such as fuzzing. Therefore, it is preferred that the glass yarn can be produced stably with good quality. In this regard, it is preferred that the glass yarn is used as a warp yarn because it tends to increase the warping speed.

(Breaking strength of glass yarn) The best breaking strength of glass yarn is 0.50~1.0 N/tex. The best range of breaking strength is 0.55~0.90 N/tex, the better range is 0.60~0.87 N/tex, and the better range is 0.65~0.85 N/tex.

If the breaking strength of glass yarn is 0.50 N/tex or more, when it is used as weft yarn, even if the weft yarn contacts the weaving machine components such as the yarn guide and is subjected to shear stress during the yarn feeding process from unwinding the weft yarn from the bobbin to ejecting it, the filaments are not easily cut and fuzz is not easily generated. Similarly, even if the ejected yarn contacts the weaving machine components such as the reed and is subjected to shear stress during the flying process, the filaments are not easily cut and fuzz is not easily generated.

If the breaking strength of glass yarn is 1.0 N/tex or less, there is a tendency that when used as weft yarn, the vibration or balloon movement of the yarn is suppressed during the yarn feeding process from unwinding the weft yarn from the bobbin to ejecting it. As a result, fuzzing caused by filament cutting is less likely to occur. It is estimated that this depends on the softness of the glass yarn.

(Constitution of glass yarn) Glass yarn is obtained by bundling a plurality of glass filaments and twisting them if necessary. In this case, the glass yarn is classified as multifilament and the glass filament is classified as monofilament.

The elastic modulus of the glass yarn is preferably 50 to 70 GPa, more preferably 50 to 63 GPa, and further preferably 53 to 63 GPa. When the elastic modulus is 50 GPa or more, the rigidity of the glass yarn is improved, and fuzzing is not easily generated during the manufacturing step. In addition, when the elastic modulus is 70 GPa or less, the brittleness resistance of the glass yarn is improved, and fuzzing is not easily generated during the manufacturing step. Furthermore, when the elastic modulus is within the above range, the glass yarn has appropriate softness, and when a mechanical load is applied, it is not easy to generate filament breakage, etc., and it is not easy to generate fuzzing and weaving defects.

(Length of twisting intervals of glass yarn) The length of twisting intervals of glass yarn is preferably 1.8 to 4.0 cm, more preferably 1.9 to 3.8 cm, more preferably 2.0 to 3.6 cm, even more preferably 2.0 to 3.4 cm, especially The optimum range is 2.0~3.2 cm, and the optimum range is 2.0~3.2 cm. If the twisting interval length of the glass yarn is less than the above upper limit, it is less likely to have a wider yarn bundle, so it is less likely to break the filament, and less likely to cause fluffing and weaving defects, so it is preferable. Furthermore, even when the ratio of the wide portions of the yarn bundles is the same, filament breakage is less likely to occur, and fuzzing and weaving defects are less likely to occur, so it is preferable. The reason for this is presumed to be that the continuous length of the wide portion of the yarn bundle can be suppressed to be short. If the twisting interval length of the glass yarn is equal to or greater than the above-mentioned lower limit, the fluff quality of the glass yarn tends to be good, and the quality of the glass cloth obtained is good, so it is preferable. It is speculated that the reason for this is that during the glass yarn manufacturing process, the torsional shear stress becomes smaller, and therefore the filament cutting during the glass yarn manufacturing process can be suppressed.

(Composition of glass yarn) As elements constituting glass yarn, 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) can be listed.

The silicon (Si) content of the glass yarn is preferably 40 to 60 mass %, more preferably 45 to 55 mass %, further preferably 47.0 to 53.5 mass %, and further preferably 48.0 to 52.0 mass % in terms of SiO _2. Si is a component that forms the skeleton structure of the glass yarn. Therefore, by making the Si content 40 mass % or more, there is a tendency that the strength of the glass yarn is further improved, and the breakage of the glass cloth is further suppressed in the subsequent steps such as the manufacturing step of the glass cloth and the manufacturing step of the prepreg using the glass cloth. In addition, by making the Si content 40 mass % or more, there is a tendency that the dielectric constant of the glass cloth is further reduced. On the other hand, when the Si content is 60 mass % or less, there is a tendency that the viscosity of the glass filaments during the manufacturing process is further reduced, and a glass fiber with a more homogeneous glass composition is obtained. Therefore, it is not easy for the obtained glass filaments to have local areas that are easy to lose transparency or local areas where bubbles are difficult to escape, so it is not easy for the glass filaments to have local areas with weak strength. As a result, the glass cloth composed of glass yarns obtained using the glass filaments is not easy to break. The Si content can be adjusted according to the amount of raw materials used in the production of the glass filaments.

The boron (B) content of _the glass yarn is preferably _15-40 mass %, more preferably 17-30 mass %, or 20-40 mass %, further preferably 18-28 mass %, further preferably 19-26 mass %, further preferably 20-25 mass %, and most preferably 20.5-24.5 mass % calculated as B 2 O 3 .

When the B content is 15% by mass or more, the dielectric constant tends to be further reduced. Also, when the B content is 15% by mass or more, the brittleness resistance of the glass cloth tends to be improved, and the glass cloth is given a moderate degree of softness or flexibility, so that when the glass yarn contacts the weaving mechanism parts such as the yarn guide and the reed, it is not easy to cause fuzzing.

On the other hand, in order to ensure the strength of the glass yarn, 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 characteristics of the glass yarn described later can be appropriately ensured.

In particular, by making the Si content in the glass yarn within the above range and making the B content within the above range, it is easy to synergistically exert the above effects related to Si and B, which is more preferable.

The B content can be adjusted by the usage (addition) of the raw materials used in the production of glass filaments. Furthermore, in the production of glass filaments, when the production conditions, usage or content can be changed, such production conditions, usage or content can be estimated in advance and the addition amount of the raw materials can be adjusted.

The aluminum (Al) content of the glass yarn is preferably 11-18% by mass, more preferably 11-17.5% by mass, and even more preferably 12-17.0% by mass, calculated as Al ₂ O _3. When the Al content is within the above range, the electrical properties and strength tend to be further improved. The Al content can be adjusted by the amount of raw materials used (addition amount) in the production of the glass filament.

The calcium (Ca) content of the glass yarn is preferably 5.0-10% by mass, more preferably 5.0-9.0% by mass, and even more preferably 5.0-8.5% by mass, calculated as CaO. When the Ca content is 5.0% by mass or more, there is a tendency that the viscosity of the glass yarn during the manufacturing process of the glass yarn is further reduced, and a glass fiber with a more homogeneous glass composition can be obtained. In addition, when the Ca content is 10% by mass or less, there is a tendency that the dielectric constant is further increased. The Ca content can be adjusted by the amount of raw materials used (addition amount) in the production of the glass yarn.

The phosphorus (P) content of the glass yarn is preferably 8.0 mass% or less, more preferably 7.0 mass% or less, and further preferably 6.0 mass% or less, calculated as P ₂ O _4. The P content is preferably more than 0 mass%. When the P content exceeds 0 mass%, the dielectric properties of the glass cloth tend to be better. In addition, when the P content is less than 8.0 mass%, the heat resistance of the glass cloth tends to be improved. The P content can be adjusted by the amount of raw materials used (addition amount) in the production of the glass filament.

Furthermore, the above-mentioned contents can be measured by ICP (Inductively Coupled Plasma) emission spectrometry. Specifically, the Si content and the B content can be obtained by dissolving the weighed glass cloth with sodium carbonate, dissolving it with dilute nitric acid and setting it to a specified volume, and measuring the obtained sample by ICP emission spectrometry. In addition, the Fe content can be obtained by dissolving the weighed glass cloth with an alkaline solution method and setting it to a specified volume, and measuring the obtained sample by 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 and setting it to a specified volume, and measuring the obtained sample by ICP emission spectrometry. In addition, as an ICP emission spectrometry device, PS3520VDD II manufactured by Hitachi High-Technologies Corporation can be used.

(Dielectric constant of glass yarn) The dielectric constant of glass yarn 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 a cavity resonance method. In this embodiment, the dielectric constant refers to the dielectric constant at a frequency of 10 GHz unless otherwise specified.

(Dielectric loss factor of glass yarn) The dielectric loss factor of glass yarn 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 factor can be measured, for example, by a cavity resonance method. In this embodiment, the dielectric loss factor refers to the dielectric loss factor at a frequency of 10 GHz unless otherwise specified.

[Method for manufacturing glass cloth] This embodiment is a method for manufacturing glass cloth having a thickness of 8 to 100 μm, which is formed by weaving glass yarns containing a plurality of glass filaments as warp yarns and weft yarns, and the glass yarns are used as weft yarns. That is, the method for manufacturing glass cloth of this embodiment includes the step of weaving the glass yarns as weft yarns. Alternatively, the glass yarns may be woven as weft yarns and warp yarns. Specifically, the present embodiment may have: a yarn preparation step (also referred to as a "yarn bundle width adjustment step" in the present embodiment), which is to prepare glass yarns, wherein when the glass yarns are measured at a length of 50 m, more than 99.96% of the length of the glass yarns are less than the yarn bundle width A, and the average yarn bundle width when measured at a length of 50 m is greater than the yarn bundle width C; a weaving step, which is to weave the prepared glass yarns to obtain glass cloth; and a fiber opening step, which is to open the glass yarns of the glass cloth. Furthermore, the present embodiment may have, as required: a de-pasting step, which is to reduce the slurry on the glass yarn attached to the glass cloth; and/or a surface treatment step, which is to perform surface treatment on the glass cloth or glass yarn by using a silane coupling agent. The following describes each step of the present embodiment.

[Yarn preparation step (yarn bundle width adjustment step)] In the yarn preparation step (yarn bundle width adjustment step), prepare the glass yarn as follows, that is, when measuring 50 m in the length direction, more than 99.96% of the yarn bundle width in the length direction is less than the yarn bundle width A, and the average yarn bundle width when measuring 50 m in the length direction is greater than the yarn bundle width C. Specifically, in the yarn bundle width adjustment step, if the yarn bundle width distribution in the length direction of the glass yarn is within the above range, the yarn is continuously used in the weaving step. If the yarn bundle width distribution is outside the range, the yarn is discarded and the glass yarn itself is replaced, or the yarn bundle width distribution is adjusted to be within the above range by rewinding the glass yarn. Furthermore, even if the yarn bundle width distribution in the length direction of the glass yarn is within the above range, the glass yarn itself can be replaced, and the yarn bundle width can also be adjusted by rewinding the glass yarn.

Alternatively, in the yarn bundle width adjustment step, the glass yarn manufacturing steps can be fed back to adjust the yarn manufacturing conditions. It is believed that the partially wide width of the glass yarn bundle is likely to occur in the portion where the tension locally acts weakly when winding the glass yarn, or in the portion where the twist density is low. Therefore, by rewinding the glass yarn or the like, it is possible to adjust the yarn bundle width distribution of the glass yarn supplied to the weaving step. When feedback is given to the manufacturing steps of the glass yarn to adjust the manufacturing conditions of the yarn, from the same point of view, by adjusting the tension when winding the glass yarn, the tension when twisting, and the like Depending on the variation range, it is possible to adjust the yarn bundle width distribution. When it is difficult to adjust by rewinding the glass yarn, etc., or from the viewpoint of production efficiency, the glass yarn itself can be replaced.

At this time, the glass yarn prepared (adjusting the yarn bundle width) has a mass per unit length of 0.5 to 30.0 tex and a density of 1.8 g/cm ³ or more and less than 2.5 g/cm ³ . In the yarn preparation step, the mass per unit length and/or density can be adjusted.

[Weaving step] The weaving step is a step of weaving the prepared glass yarn to obtain glass cloth. The weaving method is to weave the weft yarn and the warp yarn in a manner to form a predetermined weaving structure. Regarding the weaving structure of the glass cloth, for example, plain weave, square weave, satin weave, twill weave and other weaving structures can be listed. Among them, the plain weave structure is more preferred.

In one embodiment, the warp yarns introduced in parallel are opened up and down by an air-jet loom, and the yarns (weft yarns) supplied from the weft yarn storage device are sent out by the jet flow of the nozzle and then passed through the opening, thereby weaving.

The weaving step may include a glass yarn ejection process, that is, the glass yarn to be the weft yarn is rolled out from the bobbin and ejected through the storage device. In the glass yarn ejection process, the glass yarn moves in a direction different from the traveling direction, such as the movement of the balloon, and is transported while interfering with the weaving machine components such as the yarn guide. Alternatively, the weft yarn is ejected and stopped repeatedly in units of the length of one weft yarn, so that the tension changes and the glass yarn is transported while interfering with the weaving machine components such as the yarn guide. As described above, in the weft yarns where the ratio of the wider yarn bundle width portion is high, it is difficult to suppress the above-mentioned interference to be small, and therefore, the obtained glass cloth is prone to generate fuzz or weaving defects.

In contrast, in this embodiment, after the above-mentioned yarn bundle width adjustment step, when the glass yarn is measured in the length direction of 50 m, more than 99.96% of the length direction is less than the yarn bundle width A, and the average yarn bundle when measured in the length direction of 50 m is greater than the yarn bundle width C. By using such glass yarn as weft yarn, the generation of fuzz or weaving defects when weaving the glass yarn (weft yarn) can be suppressed. In this way, the uniformity of the quality of the glass cloth in the plane and the uniformity between batches can be improved. Furthermore, the weaving method is not limited to the air jet weaving machine method, and can also be a water jet or shuttle method.

The weaving speed of the weft yarns constituting the glass cloth is preferably more than 350 yarns per minute. Generally speaking, if the production speed (weaving machine rotation speed) increases, the quality of the glass cloth tends to decrease, but according to this embodiment, even when the weaving machine rotation speed exceeds 350 rpm, a glass cloth of excellent quality can be obtained. Even if the weaving speed of the weft yarns is more than 400 yarns/minute, more than 500 yarns/minute, or more than 560 yarns/minute, as long as the embodiment is used, a glass cloth of excellent quality can be obtained. Furthermore, the weaving speed of the weft yarns is preferably less than 1000 yarns/minute, less than 800 yarns/minute, or less than 700 yarns/minute.

According to this embodiment, even when the production speed of the fabric is increased to ensure a stable supply to the market, it is possible to produce a glass cloth with less uneven quality, good quality, and low dielectric. In this regard, there is a strong expectation to expand the scope of use of high-speed communication systems represented by the fifth-generation mobile communication system, that is, to supplement communication infrastructure such as base stations. Based on this background, there is also a strong expectation to increase the production speed of low-dielectric glass cloth as a component required for communication infrastructure and its stable supply. This embodiment lives up to this expectation. In other words, the glass cloth and glass yarn of this embodiment are suitable for use as glass cloth and glass yarn for high-speed communication infrastructure. Furthermore, "high-speed communication infrastructure" refers to the infrastructure (base) used to achieve high-speed communication, including various industry bases represented by high-speed communication base stations.

The weaving density of the warp yarn and the weft yarn constituting the glass cloth is preferably 30 to 90 yarns/inch, more preferably 40 to 80 yarns/inch, and further preferably 50 to 75 yarns/inch. The weaving density of the warp yarn can be controlled by adjusting the interval between the warp yarns introduced in parallel, and the weaving density of the weft yarn can be controlled by the number of times the weft yarn is sprayed from the nozzle per unit time and the flow speed of the warp yarn. Furthermore, 1 inch is 25.4 mm, so the weaving density per inch can be converted into the weaving density of the millimeter level.

Furthermore, 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 is within the above range, a thinner glass cloth with relatively higher strength tends to be obtained. The cloth mass (unit area mass) 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 , and particularly preferably 7 to 96 g/m ² .

[Fiber opening step] The fiber opening step is to open the glass fibers of the glass cloth. As fiber opening methods, for example, there are methods of fiber opening processing by spraying water (high-pressure water fiber opening), vibration cleaning machine, ultrasonic water, roller press, etc.

[Debinding step] The debinding step is to reduce the sizing agent (also called "sizing agent") attached to the glass cloth. As a debinding method, for example, a method of reducing the sizing agent by heating can be cited.

[Surface treatment step] The surface treatment step is to perform surface treatment on glass cloth or glass yarn by using a silane coupling agent. As a surface treatment method, there can be listed a method of bringing a surface treatment agent containing a silane coupling agent into contact with glass cloth or glass yarn and drying. As for bringing the surface treatment agent into contact with glass cloth or glass yarn, there can be listed a method of making the glass cloth or glass yarn soaked in the surface treatment agent; a method of applying the surface treatment agent to the glass cloth or glass yarn using a roll coater, a die coater, or a gravure coater, etc. As a drying method of the surface treatment agent, there can be listed, for example, hot air drying and a drying method using electromagnetic waves.

(Surface treatment) Glass cloth or glass yarn may be surface treated with a surface treatment agent. Examples of surface treatment agents include silane coupling agents, and water, organic solvents, acids, dyes, pigments, surfactants, etc. may also be used as needed.

As a silane coupling agent, for example, a compound represented by the following formula (11) can be cited, namely: X(R)3-nSiYn         (11) (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 independently an alkoxy group, n is an integer from 1 to 3, and R is independently a group selected from the group consisting of methyl, ethyl and phenyl groups). In formula (11), X is preferably an organic functional group having at least three of an amino group and an unsaturated double bond group, and X is more preferably an organic functional group having at least four of an amino group and an unsaturated double bond group.

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

Specific examples of silane coupling agents 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. Its 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, methacryloyloxypropyltrimethylsilane, acryloxypropyltrimethoxysilane and other known monomers, or mixtures thereof.

The molecular weight of the silane coupling agent is preferably 100 to 600, more preferably 150 to 500, and further preferably 200 to 450. It is preferred to use two or more silane coupling agents with different molecular weights. By treating the surface of the glass cloth with two or more silane coupling agents with different molecular weights, the density of the surface treatment agent on the surface of the glass cloth increases, and the reactivity with the base resin tends to be further improved.

[Glass cloth] The glass cloth of this embodiment is a glass cloth including the above-mentioned glass yarn as a weft yarn. In one embodiment, the glass cloth may also include the above-mentioned glass yarn as a weft yarn and a warp yarn. The manufacturing method of the glass cloth has at least a yarn preparation step (yarn bundle width adjustment step) as described above.

(Dielectric constant of glass cloth) The dielectric constant of the obtained glass cloth 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 a cavity resonance method. Furthermore, in this embodiment, when the dielectric constant is mentioned, it refers to the dielectric constant at a frequency of 10 GHz unless otherwise specified.

(Dielectric loss factor of glass cloth) The dielectric loss factor of the obtained glass cloth is preferably 0.0050 or less, more preferably 0.0040 or less, further preferably 0.0030 or less, and particularly preferably 0.0025 or less at a frequency of 10 GHz. The dielectric constant can be measured, for example, by a cavity resonance method. Furthermore, in this embodiment, when the dielectric constant is mentioned, it refers to the dielectric constant at a frequency of 10 GHz unless otherwise specified.

[Prepreg] The prepreg of the present embodiment has a glass cloth obtained in the above manner and a base resin composition impregnated in the glass cloth. The prepreg having the above glass cloth has less uneven quality and a higher yield of the final product. In addition, the prepreg has excellent dielectric properties and excellent moisture absorption resistance, so it is also possible to provide a printed wiring board that is not easily affected by the use environment (especially the change of the dielectric constant is small in a high humidity environment).

The prepreg of this embodiment can be manufactured by a conventional method. For example, it can be manufactured by impregnating glass cloth with a varnish prepared by diluting a base resin such as epoxy resin with an organic solvent, and then volatilizing the organic solvent in a drying furnace to cure the thermosetting resin to the B stage state (semi-cured state).

As the matrix resin composition, in addition to the above-mentioned epoxy resin, there are thermosetting resins such as dimaleimide resin, cyanate resin, unsaturated polyester resin, polyimide resin, BT (Bismaleimide Triazine) resin, and functionalized polyphenylene ether resin; thermoplastic resins such as polyphenylene ether resin, polyetherimide resin, liquid crystal polymer (LCP) of wholly aromatic polyester, polybutadiene, and fluorine resin; and mixed resins thereof. From the viewpoint of improving dielectric properties, heat resistance, solvent resistance, and press moldability, a resin obtained by modifying a thermoplastic resin with a thermosetting resin may be used as the base resin composition.

In addition, the base resin composition may also include inorganic fillers such as silicon oxide and aluminum hydroxide; flame retardants such as bromine, phosphorus, and metal hydroxide; other silane coupling agents; thermal stabilizers; antistatic agents; ultraviolet absorbers; pigments; colorants; lubricants, etc.

[Printed wiring board] The printed wiring board of this embodiment has the above-mentioned prepreg. The printed wiring board of this embodiment has less uneven quality and higher yield of the final product. In addition, due to its excellent dielectric properties and excellent moisture absorption resistance, it can also play the effect of being less affected by the use environment (especially the change of dielectric constant in high humidity environment is smaller). [Example]

Hereinafter, the present invention will be described in more detail using examples and comparative examples. The present invention is not limited to the following examples.

[Physical properties of glass yarn and glass cloth] The physical properties of glass yarn and glass cloth, specifically the thickness of 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 weaving density (weaving density) of the warp yarn and weft yarn are measured in accordance with JIS R3420.

[Electrical properties of glass cloth] The dielectric constant and dielectric dissipation factor of each glass cloth were measured in accordance with JIS R1641/IEC 62562, which specifies the method for measuring the dielectric properties of precision ceramic materials for dielectric substrates used mainly in microwave circuits in the microwave band. Specifically, glass cloth samples sampled according to the size required for the measurement in each resonator were stored in a constant temperature and humidity oven at 23°C and 50%RH for more than 8 hours to control the humidity, and then measured using a split cylindrical resonator (manufactured by EM-Lab) and an impedance analyzer (manufactured by Agilent Technologies). Each sample was measured 5 times and the average value was calculated. Furthermore, the thickness of each sample was measured by dividing the mass per unit area of each glass cloth by the density to obtain the converted thickness. The electrical properties of the glass cloth were measured for the glass cloth obtained in Examples 1, 10, 11 and Reference Example 1. Converted thickness (μm) = mass per unit area (g/m ² ) ÷ density (g/cm ³ )

[Elastic coefficient] The elastic coefficient of glass yarn is measured by the pulse echo superposition method using a glass block obtained by melting and cooling the glass yarn as a test piece.

[Composition of glass yarn] The composition of glass yarn is determined by ICP emission spectrometry. Specifically, the Si content and B content are determined as follows. After weighing the glass cloth, it is decomposed by sodium hydroxide under pressure, dissolved by dilute nitric acid and filtered to separate the insoluble parts. The insoluble matter is dissolved by sodium carbonate and dissolved by dilute nitric acid, and the volume is set to a specified value together with the filter liquid to obtain a sample. The obtained sample is measured by ICP emission spectrometry, and the Si content and B content are obtained by SiO ₂ conversion and B ₂ O ₃ conversion respectively.

In addition, the Al content, Ca content, Mg content, and P content are measured in the following manner. 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 filtering. The filter liquid is set to 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 set the specified volume. The solutions (samples) set to the specified volumes are measured by ICP emission spectrometry to find the content in the sample and convert it into an oxide value corresponding to the target metal element. Furthermore, as an ICP emission spectrometry analyzer, PS3520VDD II manufactured by Hitachi High-Technologies Corporation is used (the same as above).

[Measurement of yarn bundle width distribution] While conveying the glass yarn at a speed of 1 m/min, the bundle width of 50 m of glass yarn was measured using a LED projection-based transmissive size measuring instrument (HIGH ACCURACY CMOS MICROMETER LS-9006MR/manufactured by KEYENCE Corporation). Based on the obtained bundle width data of 50 m in length, the proportion of bundle widths below the specified width and the average bundle width were calculated.

The yarn width measurement of the LED projection type through-type sizer is performed under the condition of obtaining 1934 points of measurement value per 1 m. In the case of an error (display of -9999 value) due to the focus misalignment of the LED, the measurement value is deleted, and the ratio of the yarn width value below the above-mentioned specific yarn width value and the average yarn width value are calculated. In addition, the measurement value that caused the error can be appropriately omitted and the calculation is performed.

The tension acting on the glass yarn when conveying the glass yarn is measured by a tension meter (control equipment (Conrol instruments ETPB-100-C0585) manufactured by SCHMIDT) and is 0.12 to 0.18 N.

[Evaluation 1: Weavability (Insufficient weft yarn length)] In the weaving step using the air jet weaving machine in the embodiment and the comparative example, the number of weaving stops was counted during the weaving of 2100 m of glass cloth, and the weavability was evaluated according to the following evaluation criteria. 6: 0 stops; 5: 1 to 2 stops; 4: 3 to 4 stops; 3: 5 to 7 stops; 2: 8 to 12 stops; 1: 13 stops or more.

[Evaluation 2: Fabric quality (coarse fuzz)] 2000 m of glass cloth was rolled out from the glass cloth roll obtained in the embodiment and the comparative example, and the presence of fuzz and weaving defects was checked. The quality was evaluated according to the following evaluation criteria. Evaluation results "1" and "2" were considered unqualified. 6: No coarse fluff larger than 1 mm was found; 5: 1 to 7 coarse fluff larger than 1 mm were found, but no coarse fluff larger than 2 mm was observed; 4: 8 to 29 coarse fluff larger than 1 mm were observed, but no coarse fluff larger than 2 mm was observed; 3: More than 30 coarse fluff larger than 1 mm and less than 2 mm were found, but no coarse fluff larger than 2 mm was observed; 2: 1 to 29 coarse fluff larger than 2 mm were found; 1: More than 30 coarse fluff larger than 2 mm were found.

[Evaluation 3: Evaluation of electrical properties of substrate (dielectric dissipation factor)] Using the glass cloth obtained in the embodiment and the comparative example, a test piece for electrical property measurement was prepared under the following conditions to measure the dielectric dissipation factor.

The glass cloth obtained in the examples and comparative examples was continuously pulled out and conveyed, while being impregnated with varnish, passed through a slit to adjust the amount of varnish applied, and then passed through a drying oven at 120°C to be dried, thereby obtaining a prepreg. The varnish used contained 65 parts by mass of methacrylated polyphenylene ether, 35 parts by mass of triallyl isocyanurate, 10 parts by mass of 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 so that the resin content was 73% by mass.

The obtained prepregs are stacked a predetermined number of times, and copper foil (GTS-MP foil, 18 μm thick, manufactured by Furukawa Electric Industries, Ltd.) is stacked on both sides of the stacked prepregs, and vacuum pressurization is performed in this state to obtain a copper foil laminate. Subsequently, the copper foil is removed from the copper foil laminate by etching to obtain a laminate.

From the obtained laminate, a test piece with a length of about 50 mm and a width of about 1.5 mm was cut in such a way that the warp of the glass cloth became the long side. After being placed in an oven at 105℃±2℃ for 2 hours, the dielectric loss factor at 10 GHz was measured under the conditions shown below. Standard conditions: The test piece was placed in a constant temperature room at 23±2℃ and relative humidity of 50±5% for 96 hours before being measured.

The measurement equipment used was a network analyzer (N5230A, manufactured by Agilent Technologies) and a cavity resonator (Cavity Resornator CP series) manufactured by Kanto Electronics Application Development Co., Ltd. The measurement was performed in an environment of 23±2℃ and 50±5% relative humidity. For each measurement, 5 test pieces were cut out and the average value was taken as the value of the dielectric loss factor.

<Weaving Test 1: Glass Cloth with a Thickness of 29 μm> [Comparative Examples 1 to 4] Glass yarns with the composition shown in the table below (average diameter of glass filaments: 5.1 μm, number of filaments: 100) were used for warp yarns and weft yarns, and the weaving machine speed of the air jet weaving machine was set to the conditions in the table below to obtain glass cloth blanks with a weaving density of 65 yarns/25 mm for the warp yarns and 67 yarns/25 mm for the weft yarns. Subsequently, a debonding treatment was performed by heating, a fiber opening step was performed by high-pressure water spraying, and then a surface treatment was performed using a silane coupling agent to produce a glass cloth with a thickness of about 29 μm.

2000 m of glass cloth was rolled out from the glass cloth roll obtained in the comparative example. The cloth quality was evaluated using the condition of a loom speed of 350 rpm (weft yarn weaving speed of 350 yarns/min) as the benchmark. A: The number of coarse fluffs larger than 2 mm was confirmed to be reduced; B: The number of coarse fluffs larger than 2 mm was confirmed to be the same; C: The number of coarse fluffs larger than 2 mm was confirmed to be increased. [Table 1] Table 1 Manufacturing of 29 μm thick glass cloth Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 condition Glass yarn composition (mass %) SiO ₂ Conversion 51.3 51.3 51.3 51.3 Al ₂ O ₃ Conversion 14.3 14.3 14.3 14.3 CaO Conversion 8.1 8.1 8.1 8.1 MgO Conversion 0.3 0.3 0.3 0.3 B ₂ O ₃ Conversion 23.1 23.1 23.1 23.1 P ₂ O ₃ Conversion 0.1 0.1 0.1 0.1 Common to weft and warp yarns Glass yarn TEX 4.86 4.86 4.86 4.86 Elastic coefficient of glass yarn (GPa) 61 61 61 61 Density of glass yarn (g/cm ³ ) 2.3 2.3 2.3 2.3 Glass fiber breaking strength (N) 3.2 3.2 3.2 3.2 Breaking strength of glass yarn (N/Tex) 0.66 0.66 0.66 0.66 Weaving Glass yarn width Lower limit of average yarn width (μm) 97 97 97 97 Average yarn width (μm) 92 92 111 111 Yarn Width A(μm) 220 220 220 220 Length direction of "yarn width A or less" (%) 99.96 99.96 99.91 99.91 Yarn Width B(μm) 199 199 199 199 "Yarn Width B or Less" in the Length Direction (%) 99.83 99.83 99.21 99.21 Maximum length of twisting interval (cm) 3.6 3.6 3.6 3.6 Warp Glass yarn width Average yarn width (μm) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Length direction of "yarn width A or less" (%) "Yarn Width B or Less" in the Length Direction (%) Maximum length of twisting interval (cm) Manufacturing conditions Weaving machine speed (rpm) 450 600 450 600 Reviews Fabric Insufficient weft yarn length 2 1 5 5 Glass cloth quality Coarse hair 6 2 6 2 Electrical properties of glass cloth Dielectric constant - - - - Dielectric dissipation factor - - - - Evaluate the electrical characteristics of substrates Dielectric dissipation factor 0.0031 0.0031 0.0031 0.0031

[Examples 1 to 11, Comparative Examples 2, 4 to 8, Reference Examples 1 to 2] Except that the weaving speed of the air jet weaving machine was set to 600 rpm, a glass cloth with a thickness of 29 μm was produced in the same manner as in Comparative Example 1.

The breaking strength of the glass yarn used in the weaving test, the weavability evaluation results during weaving, the quality of the glass cloth, and the electrical characteristics are shown in the following table.

[Table 2] Table 2 Manufacturing of 29 μm thick glass cloth Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Embodiment 6 Embodiment 7 Embodiment 8 Embodiment 9 Embodiment 10 Embodiment 11 condition Glass yarn composition (mass %) SiO ₂ Conversion 51.3 51.3 51.3 51.3 51.3 51.3 51.3 51.3 51.3 49.8 53.3 Al ₂ O ₃ Conversion 14.3 14.3 14.3 14.3 14.3 14.3 14.3 14.3 14.3 16.8 14.6 CaO Conversion 8.1 8.1 8.1 8.1 8.1 8.1 8.1 8.1 8.1 3.2 4.2 MgO Conversion 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.1 5.1 B ₂ O ₃ Conversion 23.1 23.1 23.1 23.1 23.1 23.1 23.1 23.1 23.1 24.2 19.2 P ₂ O ₃ Conversion 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 4.0 <0.1 Common to weft and warp yarns Glass yarn TEX 4.86 4.86 4.86 4.86 4.86 4.86 4.86 4.86 4.86 4.67 5.01 Elastic coefficient of glass yarn (GPa) 61 61 61 61 61 61 61 61 61 56 64 Density of glass yarn (g/cm ³ ) 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 Glass fiber breaking strength (N) 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.2 3.3 3.6 Breaking strength of glass yarn (N/Tex) 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.66 0.70 0.72 Weaving Glass yarn width Lower limit of average yarn width (μm) 97 97 97 97 97 97 97 97 97 95 98 Average yarn width (μm) 110 116 121 121 110 111 110 110 110 109 115 Yarn Width A(μm) 220 220 220 220 220 220 220 220 220 217 222 Length direction of "yarn width A or less" (%) 100.00 99.99 99.98 99.97 100.00 99.98 99.98 99.98 99.98 100.00 99.99 Yarn Width B(μm) 199 199 199 199 199 199 199 199 199 187 192 "Yarn Width B or Less" in the Length Direction (%) 99.96 99.89 99.63 97.89 99.95 99.61 99.65 99.59 99.66 99.97 99.88 Maximum length of twisting interval (cm) 3.6 3.6 3.6 3.6 3.6 2.9 3.1 3.3 4.2 3.5 3.6 Warp Glass yarn width Average yarn width (μm) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) 112 Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Length direction of "yarn width A or less" (%) 99.90 "Yarn Width B or Less" in the Length Direction (%) 99.11 Maximum length of twisting interval (cm) 3.6 Manufacturing conditions Weaving machine speed (rpm) 600 600 600 600 600 600 600 600 600 600 600 Reviews Fabric Insufficient weft yarn length 5 6 6 6 5 6 6 6 6 5 5 Glass cloth quality Coarse hair 6 5 4 3 6 6 5 5 3 6 4 Electrical properties of glass cloth Dielectric constant 4.4 - - - - - - - - 4.2 4.4 Dielectric dissipation factor 0.0023 - - - - - - - - 0.0015 0.0023 Evaluate the electrical characteristics of substrates Dielectric dissipation factor 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0031 0.0026 0.0033

[Table 3] Table 3 Manufacturing of 29 μm thick glass cloth Comparison Example 2 Comparison Example 4 Comparison Example 5 Comparison Example 6 Comparison Example 7 Comparative Example 8 Reference Example 1 Reference Example 2 condition Glass yarn composition (mass %) SiO ₂ Conversion 51.3 51.3 51.3 51.3 49.8 53.3 53.1 53.1 Al ₂ O ₃ Conversion 14.3 14.3 14.3 14.3 16.8 14.6 15.4 15.4 CaO Conversion 8.1 8.1 8.1 8.1 3.2 4.2 21.0 21.0 MgO Conversion 0.3 0.3 0.3 0.3 0.1 5.1 1.9 1.9 B ₂ O ₃ Conversion 23.1 23.1 23.1 23.1 24.2 19.2 8.0 8.0 P ₂ O ₃ Conversion 0.1 0.1 0.1 0.1 4.0 <0.1 <0.1 <0.1 Common to weft and warp yarns Glass yarn TEX 4.86 4.86 4.86 4.86 4.67 5.01 5.50 5.50 Elastic coefficient of glass yarn (GPa) 61 61 61 61 56 64 73 73 Density of glass yarn (g/cm ³ ) 2.3 2.3 2.3 2.3 2.3 2.3 2.6 2.6 Glass fiber breaking strength (N) 3.2 3.2 3.2 3.2 3.3 3.6 4.5 4.5 Breaking strength of glass yarn (N/tex) 0.66 0.66 0.66 0.66 0.70 0.72 0.82 0.82 Weaving Glass yarn width Lower limit of average yarn width (μm) 97 97 97 97 95 98 103 103 Average yarn width (μm) 92 111 114 115 109 116 111 128 Yarn Width A(μm) 220 220 220 220 217 222 228 228 Length direction of "yarn width A or less" (%) 99.96 99.91 98.92 97.28 99.92 99.89 100.00 99.82 Yarn Width B(μm) 199 199 199 199 187 192 198 198 "Yarn Width B or Less" in the Length Direction (%) 99.83 99.21 96.11 90.84 99.13 97.62 99.93 99.42 Maximum length of twisting interval (cm) 3.6 3.6 3.6 3.6 3.5 3.5 3.6 3.6 Warp Glass yarn width Average yarn width (μm) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Length direction of "yarn width A or less" (%) "Yarn Width B or Less" in the Length Direction (%) Maximum length of twisting interval (cm) Manufacturing conditions Weaving machine speed (rpm) 600 600 600 600 600 600 600 600 Reviews Fabric Insufficient weft yarn length 1 5 6 6 5 5 3 5 Glass cloth quality Coarse hair 2 2 1 1 2 1 6 6 Electrical properties of glass cloth Dielectric constant - - - - - - 5.7 - Dielectric dissipation factor - - - - - - 0.0062 - Evaluate the electrical characteristics of substrates Dielectric dissipation factor 0.0031 0.0031 0.0031 0.0031 0.0026 0.0033 0.0077 0.0076

In the manufacturing methods of Examples 1 to 11, glass cloth excellent in weavability and fabric quality can be obtained. Among them, the quality of the glass cloth was particularly excellent in Examples 1, 2, 3, 5, 6, 7, 8, 10, and 11, in which the ratio of the portions with wide yarn bundle widths in the weft yarns was small. In addition, Examples 6, 7, and 8 in which the maximum value of the twist interval length falls within the prescribed range are comparable to Example 3 in which the ratio of the existence of the portion with a wide yarn bundle width is equal and the maximum value of the twist interval length is relatively large. Compared to this, glass cloth with better fabric quality can be obtained.

In Example 11, although the proportion of the wider yarn bundle is small, there is a tendency to produce slightly more coarse fuzz than in Examples 1, 2, 5, 6, 7, 8, and 10. The inventors estimate that the reason is that the elastic modulus of the fabric obtained in Example 11 is relatively large.

In Example 5, the warp yarns use glass yarns with more wide yarn bundle width parts, but the weft yarns use glass yarns with fewer wide yarn bundle width parts, so that glass cloth with good fabric quality can be obtained. In contrast, in Example 4, where the ratio of wide yarn width (weft yarn width) parts is slightly higher than that of Example 5, there is a tendency to generate slightly more coarse fuzz.

In Comparative Examples 2 and 4, if the loom speed is increased to 600 rpm, more coarse fuzz will be generated, and only glass cloth of poor quality will be obtained. In addition, in Comparative Examples 1 and 2, the yarn bundle width of the glass yarn is generally small, so sufficient flying performance cannot be obtained, and more weft yarn length is insufficient, resulting in poor weaving performance. According to Comparative Examples 1 to 4, the following tendency is found, that is, as the production speed increases, the quality of the fabric decreases.

In the manufacturing method of Examples 1 to 11, high-quality glass cloth can be obtained even if the weaving machine speed is 600 rpm. Reference Examples 1 and 2 show the manufacture of glass cloth using the previous E glass yarn. Although glass cloth with excellent weavability and quality can be obtained, the electrical characteristics are not as good as those of the glass cloth of Examples 1 to 11.

[Examples 12 to 14, 35, 36, Comparative Examples 9, 16] <Weaving Test 2: Glass Cloth with a Thickness of 14 μm> Glass yarns having the composition shown in the table below (average diameter of glass filaments: 4.0 μm, number of filaments: 50) were used for warp yarns and weft yarns. Under the condition of a weaving speed of 600 rpm (weaving speed of weft yarns: 600 yarns/minute) on an air-jet weaving machine, a glass cloth with a weaving density of 95 yarns/25 mm for warp yarns and 95 yarns/25 mm for weft yarns was obtained. Next, the debonding process was carried out by heating, the fiber opening process was carried out by high-pressure water spraying, and then the surface treatment was carried out using a silane coupling agent to produce a glass cloth with a thickness of about 14 μm. The breaking strength of the glass yarn used in the weaving test, the weavability evaluation results during weaving, and the quality of the glass cloth are shown in the following table.

[Table 4] Table 4 Glass cloth with a thickness of 14 μm Embodiment 12 Embodiment 13 Embodiment 14 Comparative Example 9 Embodiment 35 Embodiment 36 Comparative Example 16 condition Glass yarn composition (mass %) SiO ₂ Conversion 53.3 53.3 53.3 53.3 99.9 99.9 99.9 Al ₂ O ₃ Conversion 14.6 14.6 14.6 14.6 <0.1 <0.1 <0.1 CaO Conversion 4.2 4.2 4.2 4.2 <0.1 <0.1 <0.1 MgO Conversion 5.1 5.1 5.1 5.1 <0.1 <0.1 <0.1 B ₂ O ₃ Conversion 19.2 19.2 19.2 19.2 <0.1 <0.1 ＜01 P ₂ O ₃ Conversion <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 ＜01 Common to weft and warp yarns Glass yarn TEX 1.47 1.47 1.47 1.47 1.44 1.44 1.44 Elastic coefficient of glass yarn (GPa) 64 64 64 64 78 78 78 Density of glass yarn (g/cm ³ ) 2.3 2.3 2.3 2.3 2.2 2.2 2.2 Glass fiber breaking strength (N) 1.2 1.2 1.2 1.2 1.5 1.5 1.5 Breaking strength of glass yarn (N/tex) 0.85 0.85 0.85 0.85 1.04 1.04 1.04 Weaving Glass yarn width Lower limit of average yarn width (μm) 38 38 38 38 37 37 37 Average yarn width (μm) 58 59 60 63 58 60 61 Yarn Width A(vm) 138 138 138 138 137 137 137 Length direction of "yarn width A or less" (%) 100.00 99.99 99.97 99.92 100.00 99.98 99.90 Yarn Width B(μm) 109 109 109 109 107 107 107 "Yarn Width B or Less" in the Length Direction (%) 99.95 99.86 97.62 97.14 99.97 99.95 98.51 Maximum length of twisting interval (cm) 3.6 3.6 3.6 3.6 3.4 3.4 3.4 Warp Glass yarn width Average yarn width (μm) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Length direction of "yarn width A or less" (%) "Yarn Width B or Less" in the Length Direction (%) Maximum length of twisting interval (cm) Manufacturing conditions Weaving machine speed (rpm) 600 600 600 600 600 600 600 Reviews Fabric Insufficient weft yarn length 5 5 5 5 5 5 5 Fabric quality Coarse hair 4 4 3 1 3 3 1

In the manufacturing methods of Examples 12 to 14, 35, and 36, glass cloths with excellent weaving properties and fabric quality can be obtained. On the other hand, the glass cloths obtained by the manufacturing methods of Comparative Examples 9 and 16 have more coarse fuzz and poor quality.

[Examples 15 to 18, Comparative Example 10] <Weaving Test 3: Glass Cloth with a Thickness of 21 μm> Glass yarns having the composition shown in the table below (average diameter of glass filaments: 4.0 μm, number of filaments: 100) were used for warp yarns and weft yarns. Under the condition of a weaving speed of 600 rpm (weaving speed of weft yarns: 600 yarns/minute) on an air-jet weaving machine, a glass cloth with a weaving density of 74 yarns/25 mm for warp yarns and 74 yarns/25 mm for weft yarns was obtained. Next, the de-paste treatment is carried out by heating, the fiber opening step is carried out by high-pressure water spraying, and then the surface treatment is carried out using a silane coupling agent to produce a glass cloth with a thickness of about 21 μm.

The breaking strength of the glass yarn used in the weaving test, the weavability evaluation results during weaving, and the quality of the glass cloth are shown in the following table.

[Table 5] Table 5 Glass cloth with a thickness of 21 μm Embodiment 15 Embodiment 16 Embodiment 17 Embodiment 18 Comparative Example 10 condition Glass yarn composition (mass %) SiO ₂ Conversion 51.3 51.3 51.3 53.3 51.3 Al ₂ O ₃ Conversion 14.3 14.3 14.3 14.6 14.3 CaO Conversion 8.1 8.1 8.1 4.2 8.1 MgO Conversion 0.3 0.3 0.3 5.1 0.3 B ₂ O ₃ Conversion 23.1 23.1 23.1 19.2 23.1 P ₂ O ₃ Conversion 0.1 0.1 0.1 <0.1 0.1 Common to weft and warp yarns Glass yarn TEX 2.90 2.90 2.90 2.95 2.90 Elastic coefficient of glass yarn (GPa) 61 61 61 64 61 Density of glass yarn (g/cm ³ ) 2.3 2.3 2.3 2.3 2.3 Glass fiber breaking strength (N) 2.2 2.2 2.2 2.4 2.2 Breaking strength of glass yarn (N/Tex) 0.77 0.77 0.77 0.82 0.77 Weaving Glass yarn width Lower limit of average yarn width (μm) 72 72 72 73 72 Average yarn width (μm) 82 88 90 90 92 Yarn Width A(μm) 184 184 184 186 184 Length direction of "yarn width A or less" (%) 100.00 99.99 99.96 100.00 99.90 Yarn Width B(μm) 160 160 160 161 160 "Yarn Width B or Less" in the Length Direction (%) 99.92 99.88 97.78 99.91 96.97 Maximum length of twisting interval (cm) 3.6 3.6 3.6 3.6 3.6 Warp Glass yarn width Average yarn width (μm) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Length direction of "yarn width A or less" (%) "Yarn Width B or Less" in the Length Direction (%) Maximum length of twisting interval (cm) Manufacturing conditions Weaving machine speed (rpm) 600 600 600 600 600 Reviews Fabric Insufficient weft yarn length 5 5 6 5 5 Fabric quality Coarse hair 6 5 3 4 1

In the manufacturing methods of Examples 15 to 18, glass cloths with excellent weaving properties and fabric quality can be obtained. On the other hand, the glass cloth obtained in the manufacturing method of Comparative Example 10 has more coarse fuzz and poor quality.

[Examples 19 to 24, Comparative Examples 11 and 12] <Weaving Test 4: Glass Cloth with a Thickness of 46 μm> Glass yarns having the composition shown in the table below (average diameter of glass filaments: 5.1 μm, number of filaments: 200) were used for warp yarns and weft yarns. Under the condition that the weaving speed of the air-jet weaving machine was 600 rpm (weaving speed of weft yarns was 600 yarns/minute), a glass cloth blank having a weaving density of 52.5 yarns/25 mm for the warp yarns and 52.5 yarns/25 mm for the weft yarns was obtained. Next, the de-paste treatment is carried out by heating, the fiber opening step is carried out by high-pressure water spraying, and then the surface treatment is carried out using a silane coupling agent to produce a glass cloth with a thickness of about 46 μm.

The breaking strength of the glass yarn used in the weaving test, the weavability evaluation results during weaving, and the quality of the glass cloth are shown in the following table.

[Table 6] Table 6 Glass cloth with a thickness of 46 μm Embodiment 19 Embodiment 20 Embodiment 21 Embodiment 22 Embodiment 23 Embodiment 24 Comparative Example 11 Comparative Example 12 condition Glass yarn composition (mass %) SiO ₂ Conversion 51.3 51.3 51.3 51.3 49.8 53.3 51.3 51.3 Al ₂ O ₃ Conversion 14.3 14.3 14.3 14.3 16.8 14.6 14.3 14.3 CaO Conversion 8.1 8.1 8.1 8.1 3.2 4.2 8.1 8.1 MgO Conversion 0.3 0.3 0.3 0.3 0.1 5.1 0.3 0.3 B ₂ O ₃ Conversion 23.1 23.1 23.1 23.1 24.2 19.2 23.1 23.1 P ₂ O ₃ Conversion 0.1 0.1 0.1 0.1 4.0 <0.1 0.1 0.1 Common to weft and warp yarns Glass yarn TEX 9.72 9.72 9.72 9.72 9.57 10.08 9.72 9.72 Elastic coefficient of glass yarn (GPa) 61 61 61 61 56 64 61 61 Density of glass yarn (g/cm ³ ) 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 Glass fiber breaking strength (N) 6.9 6.9 6.9 6.9 6.7 7.3 6.9 6.9 Breaking strength of glass yarn (N/Tex) 0.71 0.71 0.71 0.71 0.70 0.72 0.71 0.71 Weaving Glass yarn width Lower limit of average yarn width (μm) 131 131 131 131 130 133 131 131 Average yarn width (μm) 146 150 155 155 152 144 155 170 Yarn Width A(μm) 267 267 267 267 266 269 267 267 Length direction of "yarn width A or less" (%) 100.00 99.99 99.98 99.97 100.00 100.00 99.92 98.50 Yarn Width B(μm) 251 251 251 251 249 253 251 251 "Yarn Width B or Less" in the Length Direction (%) 99.93 99.86 99.60 97.65 99.90 99.88 98.44 93.10 Maximum length of twisting interval (cm) 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 Warp Glass yarn width Average yarn width (μm) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Length direction of "yarn width A or less" (%) "Yarn Width B or Less" in the Length Direction (%) Maximum length of twisting interval (cm) Manufacturing conditions Weaving machine speed (rpm) 600 600 600 600 600 600 600 600 Reviews Fabric Insufficient weft yarn length 5 5 6 6 5 5 5 5 Fabric quality Coarse hair 6 5 5 3 6 5 2 1

In the manufacturing methods of Examples 19 to 24, glass cloths with excellent weaving properties and fabric quality can be obtained. On the other hand, the glass cloths obtained in the manufacturing methods of Comparative Examples 11 and 12 have more coarse fuzz and poor quality.

[Examples 25 to 28, Comparative Example 13] <Weaving Test 5: Glass Cloth with a Thickness of 73 μm> Glass yarns having the composition shown in the table below (average diameter of glass filaments: 6.1 μm, number of filaments: 200) were used for warp yarns and weft yarns. Under the condition of a weaving speed of 600 rpm (weaving speed of weft yarns: 600 yarns/minute) on an air-jet weaving machine, a glass cloth with a weaving density of 59 yarns/25 mm for warp yarns and 61 yarns/25 mm for weft yarns was obtained. Next, the de-paste treatment is carried out by heating, the fiber opening step is carried out by high-pressure water spraying, and then the surface treatment is carried out using a silane coupling agent to produce a glass cloth with a thickness of about 73 μm.

The breaking strength of the glass yarn used in the weaving test, the weavability evaluation results during weaving, and the quality of the glass cloth are shown in the following table.

[Table 7] Table 7 Glass cloth with a thickness of 73 μm Embodiment 25 Embodiment 26 Embodiment 27 Embodiment 28 Comparative Example 13 condition Glass yarn composition (mass %) SiO ₂ Conversion 51.3 51.3 51.3 51.3 51.3 Al ₂ O ₃ Conversion 14.3 14.3 14.3 14.3 14.3 CaO Conversion 8.1 8.1 8.1 8.1 8.1 MgO Conversion 0.3 0.3 0.3 0.3 0.3 B ₂ O ₃ Conversion 23.1 23.1 23.1 23.1 23.1 P ₂ O ₃ Conversion 0.1 0.1 0.1 0.1 0.1 Common to weft and warp yarns Glass yarn TEX 14.6 14.6 14.6 14.6 14.6 Elastic coefficient of glass yarn (GPa) 61 61 61 61 61 Density of glass yarn (g/cm ³ ) 2.3 2.3 2.3 2.3 2.3 Glass fiber breaking strength (N) 10.4 10.4 10.4 10.4 10.4 Breaking strength of glass yarn (N/Tex) 0.71 0.71 0.71 0.71 0.71 Weaving Glass yarn width Lower limit of average yarn width (μm) 151 151 151 151 151 Average yarn width (μm) 165 168 174 175 188 Yarn Width A(μm) 294 294 294 294 294 Length direction of "yarn width A or less" (%) 100.00 99.99 99.97 99.97 99.95 Yarn Width B(μm) 281 281 281 9997 281 "Yarn Width B or Less" in the Length Direction (%) 99.71 99.15 98.35 97.21 95.43 Maximum length of twisting interval (cm) 3.6 3.6 3.6 3.6 3.6 Warp Glass yarn width Average yarn width (μm) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Length direction of "yarn width A or less" (%) "Yarn Width B or Less" in the Length Direction (%) Maximum length of twisting interval (cm) Manufacturing conditions Weaving machine speed (rpm) 600 600 600 600 600 Reviews Fabric Insufficient weft yarn length 4 4 4 5 4 Fabric quality Coarse hair 6 4 4 3 1

In the manufacturing methods of Examples 25 to 28, glass cloths with excellent weaving properties and fabric quality can be obtained. On the other hand, the glass cloth obtained in the manufacturing method of Comparative Example 13 has more coarse fuzz and poor quality.

[Examples 29 to 34, Comparative Examples 14 and 15] <Weaving Test 6: Glass Cloth with a Thickness of 92 μm> Glass yarns having the composition shown in the table below (average diameter of glass filaments: 6.1 μm, number of filaments: 200) were used for warp yarns and weft yarns. Under the condition of a weaving speed of 600 rpm (weaving speed of weft yarns: 600 yarns/min) on an air-jet weaving machine, a glass cloth with a weaving density of 60 yarns/25 mm for warp yarns and 57 yarns/25 mm for weft yarns was obtained. Next, the de-paste treatment is carried out by heating, the fiber opening step is carried out by high-pressure water spraying, and then the surface treatment is carried out using a silane coupling agent to produce a glass cloth with a thickness of about 92 μm.

The breaking strength of the glass yarn used in the weaving test, the weavability evaluation results during weaving, and the quality of the glass cloth are shown in the following table.

[Table 8] Table 8 Glass cloth with a thickness of 92 μm Embodiment 29 Embodiment 30 Embodiment 31 Embodiment 32 Embodiment 33 Embodiment 34 Comparative Example 14 Comparative Example 15 condition Glass yarn composition (mass %) SiO ₂ Conversion 51.3 51.3 51.3 51.3 49.8 53.3 51.3 51.3 Al ₂ O ₃ Conversion 14.3 14.3 14.3 14.3 16.8 14.6 14.3 14.3 CaO Conversion 8.1 8.1 8.1 8.1 3.2 4.2 8.1 8.1 MgO Conversion 03 0.3 0.3 0.3 0.1 5.1 0.3 0.3 B ₂ O ₃ Conversion 23.1 23.1 23.1 23.1 24.2 19.2 23.1 23.1 P ₂ O ₃ Conversion 0.1 0.1 0.1 0.1 4.0 <0.1 0.1 0.1 Common to weft and warp yarns Glass yarn TEX 19.4 19.4 19.4 19.4 19.1 20.06 19.4 19.4 Elastic coefficient of glass yarn (GPa) 61 61 61 61 56 64 61 61 Density of glass yarn (g/cm ³ ) 2.3 2.3 2.3 2.3 2.3 2.3 2.3 2.3 Glass fiber breaking strength (N) 13.6 13.6 13.6 13.6 13.2 14.8 13.6 13.6 Breaking strength of glass yarn (N/Tex) 0.70 0.70 0.70 0.70 0.69 0.74 0.70 0.70 Weaving Glass yarn width Lower limit of average yarn width (μm) 165 165 165 165 164 166 165 165 Average yarn width (μm) 180 182 190 190 188 187 190 209 Yarn Width A(μm) 314 314 314 314 313 316 314 314 Length direction of "yarn width A or less" (%) 100.00 99.99 99.98 99.97 100.00 100.00 99.93 96.10 Yarn Width B(μm) 302 302 302 302 301 305 302 302 "Yarn Width B or Less" in the Length Direction (%) 99.95 99.87 99.59 97.53 99.96 99.95 98.21 91.21 Maximum length of twisting interval (cm) 3.6 3.6 3.6 3.6 3.6 3.6 3.6 3.6 Warp Glass yarn width Average yarn width (μm) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Same as weft yarn (same batch) Length direction of "yarn width A or less" (%) "Yarn Width B or Less" in the Length Direction (%) Maximum length of twisting interval (cm) Manufacturing conditions Weaving machine speed (rpm) 600 600 600 600 600 600 600 600 Reviews Fabric Insufficient weft yarn length 5 5 6 5 5 5 5 5 Fabric quality Coarse hair 6 5 5 3 6 5 2 1

In the manufacturing methods of Examples 29 to 34, glass cloths with excellent weaving properties and fabric quality can be obtained. On the other hand, the glass cloths obtained in the manufacturing methods of Comparative Examples 14 and 15 have more coarse fuzz and poor quality.

Claims (22)

A method for manufacturing glass cloth, wherein a glass cloth having a thickness of 8 to 100 μm is woven from glass yarns comprising a plurality of glass filaments as warp yarns and weft yarns, wherein the weft yarns are glass yarns having a mass per unit length of 0.5 to 30.0 tex, a density of 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , and when measured in a length direction of 50 m, 99.96% or more of the length direction is less than or equal to the yarn bundle width A (unit: μm) expressed by the following formula (1): A=68×ln(x)+112 (1) x: tex of glass yarn, and the average yarn bundle width when measured in the longitudinal direction of 50 m is greater than the lower limit value C (unit: μm) expressed by the following formula (2): C = 49.0 × ln (x) + 19.5 (2) x: tex of glass yarn. A method for manufacturing glass cloth as claimed in claim 1, wherein the weft yarn is a glass yarn such that, when measured in the length direction of 50 m, 98.00% or more of the length direction is less than the yarn bundle width B (unit: μm) represented by the following formula (3): B = 75 × ln (x) + 80 (3) x: tex of the glass yarn. For example, the manufacturing method of glass cloth according to claim 1 or 2, wherein the twisting interval length of the above-mentioned glass yarn is 1.8~4.0cm. The method for producing glass cloth according to claim 1 or 2, wherein the glass yarn having a silicon (Si) content of 40-60 mass % calculated as silicon dioxide (SiO ₂ ) and a boron (B) content of 15-40 mass % calculated as boron oxide (B ₂ O ₃ ) is used as the weft yarn. The method for producing glass cloth according to claim 4, wherein the glass yarn having a boron (B) content of 20-40% by mass calculated as boron oxide (B ₂ O ₃ ) is used as the weft yarn. A method for manufacturing glass cloth as claimed in claim 1 or 2, wherein the glass yarn having an elastic modulus of 50 to 70 GPa is used as the weft yarn. A method for manufacturing glass cloth as claimed in claim 1 or 2, wherein the glass yarn having an elastic modulus of 50 to 63 GPa is used as the weft yarn. A method for manufacturing glass cloth as claimed in claim 1 or 2, wherein the weft yarn is woven at a weaving speed of more than 350 yarns and less than 1000 yarns per minute. A glass yarn is a glass yarn used for weft yarn of glass cloth, wherein the mass per unit length of the glass yarn is 0.5-30.0 tex, the density is 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , and when measured in the length direction of 50 m, more than 99.96% of the yarn bundle width in the length direction is less than the yarn bundle width A (unit: μm) expressed by the following formula (1), wherein the formula (1) is: A=68×ln(x)+112 (1) x: tex of the glass yarn, and the average yarn bundle width when measured in the length direction of 50 m is greater than the lower limit value C (unit: μm) expressed by the following formula (2), wherein the formula (2) is: C=49.0×ln(x)+19.5 (2) x: tex of the glass yarn. For example, the glass yarn of claim 9, wherein when the length of the glass yarn is 50 m, more than 98.00% of the length of the glass yarn is less than the yarn bundle width B (unit: μm) shown by the following formula (3), where formula (3) is: B = 75 × ln (x) + 80 (3) x: tex of the glass yarn. Such as the glass yarn of claim 9 or 10, wherein the twisting interval length of the above-mentioned glass yarn is 1.8~4.0cm. The glass yarn of claim 9 or 10, wherein the silicon (Si) content is 40-60 mass % calculated as silicon dioxide (SiO ₂ ) and the boron (B) content is 15-40 mass % calculated as boron oxide (B ₂ O ₃ ). The glass yarn of claim 12, wherein the boron (B) content is 20-40 mass % calculated as boron oxide (B ₂ O ₃ ). For example, the glass yarn in claim 9 or 10 has an elastic modulus of 50~70GPa. For example, the glass yarn in claim 9 or 10 has an elastic modulus of 50~63GPa. The glass yarn of claim 9 or 10 has a dielectric constant of less than 5.0 at a frequency of 10 GHz. The glass yarn of claim 9 or 10 has a dielectric dissipation factor of less than 0.0050 at a frequency of 10 GHz. The glass yarn of claim 9 or 10 is used for weaving glass cloth, and the glass cloth is used for high-speed communication infrastructure. A glass cloth comprising the glass yarn as claimed in claim 9 or 10. The glass cloth of claim 19 has a dielectric constant of less than 5.0 at a frequency of 10 GHz. Glass cloth as claimed in claim 19 or 20, which is used for high-speed communication infrastructure. A glass yarn screening method is suitable for producing a glass cloth woven with the glass yarn as warp yarn and weft yarn, comprising the following steps: as the above-mentioned weft yarn, the following glass yarn is screened, that is, the mass per unit length is 0.5-30.0 tex, the density is 1.8 g/cm ³ or more and less than 2.5 g/cm ³ , and when the length direction is 50 m, more than 99.96% of the length direction is less than the yarn bundle width A (unit: μm) represented by the following formula (1), and the formula (1) is: A=68×ln(x)+112 (1) x: tex of glass yarn, and the average yarn bundle width when measured in the longitudinal direction of 50 m is greater than the lower limit value C (unit: μm) expressed by the following formula (2): C = 49.0 × ln (x) + 19.5 (2) x: tex of glass yarn.