JP2022183025A - Glass thread, method for producing glass cloth, and glass cloth - Google Patents

Abstract

An object of the present invention is to provide a glass cloth with few defects, a method for producing the same, and a glass thread constituting the same. The glass cloth is woven from glass yarns containing a plurality of glass filaments as warp and weft yarns. When observing every 1 m in the length direction and counting the number of defects as 1 when fluff is present on the entire surface of the cloth, the following formula: deduction rate (%) = (total count of defects / 500) x 100 The deduction rate represented is 0 to 3.5%. [Selection figure] None

Description

TECHNICAL FIELD The present invention relates to a glass thread, a method for producing a glass cloth, and a glass cloth.

2. Description of the Related Art With the recent development of information communication society, data communication and/or signal processing have come to be performed in large capacity and at high speed. Printed wiring boards are used in high-end servers, high-end routers/switches, supercomputers, base station communication equipment, measuring instruments, and the like, and the dielectric constant of printed wiring boards is becoming lower. Therefore, low-dielectric glass cloth has been proposed as a glass cloth constituting a printed wiring board. For example, Patent Document 1 discloses that a large amount of diboron trioxide (B ₂ O ₃ ) is blended in the glass composition and silicon dioxide (SiO ₂ ) or the like is added to the conventionally used E glass cloth. It is disclosed that the glass cloth can be made to have a low dielectric strength by adjusting the blending amount of the component (2).

Since terminal electronic devices such as smartphones are also required to support high-capacity and high-speed communication, the reduction in the dielectric strength of printed wiring boards used for smartphones has begun to expand in recent years. Therefore, thin (for example, 10 to 50 μm thick) low-dielectric glass cloth is strongly desired.

JP-A-11-292567 JP 2013-112917 A Japanese Patent Application Laid-Open No. 2004-115351 JP 2011-140721 A WO2018/216637

As a result of studies by the present inventors, it has been found that the low-dielectric glass cloth described in Patent Document 1 has variations in performance or quality compared with the conventionally known E-glass cloth. In particular, a low-dielectric glass cloth having a thickness of 10 to 50 μm is likely to cause large fluctuations in fluff quality, so that it has been difficult to stably obtain a glass cloth with excellent fluff quality.

As a method for improving the fluff quality of glass cloth, Patent Documents 2 and 3 use a specific starch as a sizing agent for glass threads, and Patent Document 4 uses a traveler to smooth the bending of the threads in the manufacture of glass threads. Patent Document 5 discloses a method of using a specific composition for a low dielectric glass.

In Patent Document 2, a glass cloth is produced using a glass yarn produced using a sizing agent in which 25 to 100% by mass of starch is composed of amylose and the starch has an average particle size of 12 μm or less. By doing so, it is possible to suppress fluffing of the cloth.

Patent document 3 improves the sizing properties of glass threads by producing glass threads to which 1.5 to 3.0% by mass of a sizing agent containing etherified high amylose starch having an amylose content of 50% or more is adhered, It is disclosed that this can effectively prevent the generation of fluff.

In Patent Document 4, in the yarn twisting process in the manufacture of glass yarn, quality defects such as fuzz, yarn breakage, loops, etc. occur by increasing the thickness of the yarn passing portion of the traveler and making the yarn bend gently when passing through the traveler. It states that it will be difficult.

Patent Document 5 discloses that the glass composition is 50≦SiO ₂ ≦56, 20≦B ₂ O ₃ ≦30, 10≦Al ₂ O ₃ ≦20, 3.5≦MgO+CaO≦10, and 0≦R ₂ in weight %. O≦1.0 (wherein R is at least one element selected from Li, Na, and K), and by forming a low dielectric glass containing Fe ₂ O ₃ , glass It is disclosed that yarn breakage or fluffing during yarn processing can be suppressed.

It is presumed that the strength of the low-dielectric glass yarn is weaker than that of the E-glass glass yarn that has been conventionally used. Due to the large variation in quality, it has not been possible to obtain a low-dielectric glass yarn from which a high-quality glass cloth can be stably obtained.

For example, by using glass threads with few defects, it is easy to improve the quality of the glass cloth. In recent years, as the quality required for glass cloth has increased, it has been desired to provide a glass cloth that can meet the expectations for such quality improvement. As an example, low-dielectric resins tend to have high molecular weights or bulky functional groups, and are inferior to conventional resins in varnish impregnation. There was a background that impregnation was required.

The present invention has been made in view of the above problems, and aims to provide a glass yarn with few defects, to provide a highly uniform and good quality glass cloth using such a glass yarn, and further to It is an object of the present invention to provide a manufacturing method.

As a result of intensive studies to solve the above problems, the present inventors have focused on the fact that fine fluff can be detected only by predetermined visual observation, and have completed the present invention. One aspect of the present invention is listed below.
[1]
A glass cloth woven using glass yarns containing a plurality of glass filaments as warps and wefts,
A white LED light is irradiated along the cloth surface for 500 m in the length direction of the glass cloth, and observation is performed every 1 m in the length direction. then the following expression:
Demerit rate (%) = (total number of defects counted / 500) x 100
A glass cloth with a demerit rate of 0 to 3.5%.
[2]
2. The glass cloth according to item 1, wherein the entire surface fluff includes fluff of 200 to 1000 μm due to broken filaments observed on the cloth surface with an optical microscope.
[3]
3. The glass cloth according to item 1 or 2, wherein the glass cloth has a thickness of 10 to 50 μm.
[4]
The following conditions:
(i) TEX is 1 to 13;
(ii) The breaking strength is 0.50 to 0.80 N / tex, and (iii) The number of filaments that have slipped more than twice the average yarn width when measuring 180 m is 3 or less.
4. The glass cloth according to any one of items 1 to 3, comprising the glass yarn satisfying
[5]
5. The glass cloth according to any one of items 1 to 4, comprising the glass yarn having a twist interval length of 1.8 to 10.0 cm.
[6]
The value obtained by dividing the difference between the maximum twist interval length and the minimum twist interval length of the glass yarn by the average twist interval length (twist interval length difference index) is 0.7 or less. , the glass cloth according to any one of items 1 to 5, comprising the glass yarn.
[7]
For the glass thread having a length of 10,000 m or more,
When measuring ranges of 180 m in the length direction are selected at five different locations, the number of filaments that have slipped at least twice the yarn width average value is 3 or less in each of the five measurement ranges. , The glass cloth according to any one of Items 1 to 6.
[8]
For the glass thread having a length of 50,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 7 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 7 measurement ranges. , The glass cloth according to any one of Items 1 to 6.
[9]
For the glass thread having a length of 100,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 10 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 10 measurement ranges. , The glass cloth according to any one of Items 1 to 6.
[10]
A method for producing a glass cloth, comprising a step of weaving using glass yarns containing a plurality of glass filaments as warps and wefts,
(i) the glass yarn has a TEX of 1 to 13;
(ii) the glass yarn has a breaking strength of 0.50 to 0.80 N/tex, and (iii) the number of filaments that have slipped at least twice the average yarn width when measured at 180 m is 3 or less. ,
A method for manufacturing a glass cloth.
[11]
11. The method for producing a glass cloth according to item 10, wherein the TEX of the glass yarn is 1-7.
[12]
12. The method for producing a glass cloth according to item 10 or 11, wherein the number of monoglass filaments constituting the glass yarn is 30 to 120.
[13]
13. The method for producing a glass cloth according to any one of items 10 to 12, wherein the twist interval length of the glass yarn is 1.8 to 10.0 cm.
[14]
The value obtained by dividing the difference between the maximum twist interval length and the minimum twist interval length of the glass yarn by the average twist interval length (twist interval length difference index) is 0.7 or less. , The method for producing a glass cloth according to any one of Items 10 to 13.
[15]
15. The method for producing a glass cloth according to any one of items 10 to 14, wherein the glass yarn has a density of 2.2 g/cm ³ or more and less than 2.5 g/cm ³ .
[16]
16. The method for producing a glass cloth according to any one of Items 10 to 15, wherein the glass yarn has an elastic modulus of 50 to 70 GPa.
[17]
17. The method for producing a glass cloth according to any one of Items 10 to 16, wherein the glass yarn has an elastic modulus of 50 to 63 GPa.
[18]
For the glass thread having a length of 10,000 m or more,
When measuring ranges of 180 m in the length direction are selected at five different locations, the number of filaments that have slipped at least twice the yarn width average value is 3 or less in each of the five measurement ranges. , The method for producing a glass cloth according to any one of Items 10 to 17.
[19]
For the glass thread having a length of 50,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 7 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 7 measurement ranges. , The method for producing a glass cloth according to any one of Items 10 to 17.
[20]
For the glass thread having a length of 100,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 10 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 10 measurement ranges. , The method for producing a glass cloth according to any one of Items 10 to 17.
[21]
(i) TEX is 1 to 13;
(ii) breaking strength is 0.50 to 0.80 N / tex, and (iii) the number of filaments that have slipped more than twice the yarn width average value when measuring 180 m is 3 or less.
glass thread.
[22]
22. The glass yarn according to item 21, wherein the TEX is 1-7.
[23]
23. The glass yarn according to item 21 or 22, wherein the number of monoglass filaments constituting the glass yarn is 30 to 120.
[24]
24. The glass yarn according to any one of items 21 to 23, having a twist interval length of 1.8 to 10.0 cm.
[25]
Items 21 to 24 in which the value obtained by dividing the difference between the maximum twist interval length and the minimum twist interval length by the average twist interval length (twist interval length difference index) is 0.7 or less. The glass yarn according to any one of .
[26]
26. The glass yarn according to any one of items 21 to 25, having a density of 2.2 g/cm ³ or more and less than 2.5 g/cm ³ .
[27]
27. The glass yarn according to any one of items 21 to 26, which has an elastic modulus of 50 to 70 GPa.
[28]
28. The glass yarn according to any one of items 21 to 27, which has an elastic modulus of 50 to 63 GPa.
[29]
For the glass thread having a length of 10,000 m or more,
When measuring ranges of 180 m in the length direction are selected at five different locations, the number of filaments that have slipped at least twice the yarn width average value is 3 or less in each of the five measurement ranges. , the glass yarn according to any one of items 21 to 28.
[30]
For the glass thread having a length of 50,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 7 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 7 measurement ranges. , the glass yarn according to any one of items 21 to 28.
[31]
For the glass thread having a length of 100,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 10 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 10 measurement ranges. , the glass yarn according to any one of items 21 to 28.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide glass yarns with few defects, to provide glass cloths with high uniformity and good quality using such glass yarns, and to provide a method for producing the same. You can also

Embodiments of the present invention (hereinafter referred to as "embodiments") will be described in detail below, but the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof. .

〔Glass cloth〕
A first embodiment of the present invention is a glass cloth.

The glass cloth of this embodiment is
A glass cloth woven using glass yarns containing a plurality of glass filaments (hereinafter also simply referred to as "filaments") as warps and wefts, wherein a predetermined measurement length of the total length in the length direction of the glass cloth When 500 (m) is observed by irradiating white LED light along the cloth surface for each cloth surface of 1 m in the length direction, and when the entire surface of the cloth surface has fluff, the number of defects is counted as 1. , the following formula:
Demerit rate (%) = total number of fluff counts on the entire surface/500 (m) x 100
The deduction rate represented by is 0 to 3.5%.

In this embodiment, by irradiating white LED light along the cross surface and observing the cross surface, compared to the conventional observation by light irradiation in the direction perpendicular to the cross surface, filament breakage of less than 1 mm in length (hereinafter also referred to as "fine fluff") can be detected with high sensitivity. Further, since the demerit rate derived by such a detection method is 0 to 3.5%, the glass cloth has few defects and is excellent in various properties. From the same point of view, the deduction rate is preferably 3.0% or less, more preferably 2.9% or less.
The conventional observation (conventional observation by light irradiation in the direction perpendicular to the cross plane) was not intended to observe fine fluff. Therefore, when based on the conventional observation method, it is impossible to detect fine fluff as assumed in this embodiment with high sensitivity, and as a result, the idea of controlling the deduction rate within the numerical range assumed in this embodiment is reached. was difficult.
A method of calculating the "point demerit rate (%)" will be described in detail in Examples.

The overall fluff includes fluff of 200 to 1000 μm due to broken filaments observed on the cloth surface with an optical microscope. As in the present embodiment, the white LED light is emitted along the cloth surface to observe the cloth surface, which makes it easy to observe such overall fluff.

The glass cloth of the present embodiment preferably has a thickness described below. Moreover, it is preferable that the glass thread for obtaining the glass cloth of this embodiment has the structure described later.

(Dielectric constant of glass cloth)
The dielectric constant of the glass cloth is preferably 5.0 or less, more preferably 4.9 or less, still more preferably 4.8 or less, particularly preferably 4.6 or less at a frequency of 10 GHz. The dielectric constant of glass cloth can be measured by a cavity resonance method. In this specification, the dielectric constant of glass cloth refers to that at a frequency of 10 GHz unless otherwise specified.

[Glass thread]
A second embodiment of the present invention is a glass thread.

The glass yarn of the second embodiment is
(i) TEX is 1 to 13;
(ii) The breaking strength is 0.50 to 0.80 N / tex, and (iii) The number of filaments that slipped more than twice the yarn width average value when measuring 180 m (hereinafter, "when measuring 180 m, the yarn The number of filaments that have slid twice or more than the average width value” is also simply referred to as the “number of filaments that have slid”) is 3 or less.

The quality of the glass cloth produced using the low-dielectric glass yarns is more varied than that of the conventional E-glass cloth. Therefore, it has been found that it is difficult to stably obtain high-quality low-dielectric glass cloth. Of these, a detailed examination of glass cloths of relatively poor quality reveals that in low-dielectric glass cloths manufactured from low-dielectric glass yarns with a number of sliding filaments outside the specified range, fluff is densely present in a band-like shape in the length direction. Many "band-like fluff defects" were observed. On the other hand, the present embodiment is based on the finding that using a low-dielectric glass yarn whose filament dropout is within a specific range can reduce the drawback of the low-dielectric glass cloth. The reason for this is not bound by theory, but the dropout of the filament is a specific value (for example, the glass yarn with the number of sliding filaments of more than 3 is unwound from the bobbin in the weaving process and then placed in a loop guide, etc.). It is thought that when the filaments are interfered with by the loom members when passing through the loom members, the number of filaments falling off increases or filament breakage is likely to occur.

In particular, the weft yarn is conveyed in a ballooning motion along the yarn path until it is unwound from the bobbin and ejected. For this reason, it is thought that the filament slippage portion is likely to receive shear stress and be cut, and that the cut filament pieces are likely to become entangled due to the swirling motion and grow into coarse fluff. In order to increase the productivity, the weft driving speed is preferably high, but it is considered that the higher the weft transport speed, the more likely the occurrence of filament drop-off or filament breakage.

The E-glass glass threads that have been used so far have a higher density and a higher strength than low-dielectric glass threads. Therefore, the glass yarn can be conveyed stably, and the degree of interference with the loom members is small, so the damage caused by interference is limited. On the other hand, low-dielectric glass yarns, which are lighter and weaker in strength, tend to sway more due to changes in tension and the like when the glass yarns are conveyed. Therefore, it is likely to interfere with the loom members, and even when it interferes with the loom members, it is likely to receive greater damage. For this reason, it is considered that the dropout of the filament is likely to increase or the breakage of the filament is likely to be facilitated.

In addition, in the case of glass yarns in which the filament dropout is greater than a specific range, the dropout portion tends to move when subjected to a physical load such as high-pressure spray water in the opening process. For this reason, the detached portion is likely to receive a load such as interference with the conveying member of the glass cloth. For the purpose of improving the in-plane uniformity of the glass cloth and improving the impregnation property, it is preferable that the opening processing force is strong. is likely to occur more frequently.

Furthermore, with low-dielectric glass yarns having a lower density and a lower strength than E-glass, the reduction in glass strength is significant in the heat cleaning process. For this reason, when performing the opening process after the heat cleaning process, it is strongly damaged by physical loads such as high-pressure water spray, and fluffing due to broken filaments or fluffing of broken filaments is more likely to occur. Conceivable. It is considered that these influences appeared as the quality of the glass cloth.

On the other hand, by using the glass yarn of the present embodiment, even when using glass yarn with a low dielectric strength and relatively light weight and low strength, the glass yarn is unwound in the weaving process and then passed through a loom member such as a loop guide. It is possible to reduce the damage received at the time of interference with the loom member at the time of squeezing. In addition, the use of the glass yarn of the present embodiment can also reduce the degree of interference of the dropped portion with the conveying member or the damage received when it interferes with the conveying member in the opening process. As a result, by using the glass yarn of the present embodiment, it is possible to suppress the generation of fluff due to filament breakage in the weaving process and the opening process, and to obtain a high-quality uniform glass cloth. In addition, the use of the above glass yarn tends to increase the weaving speed (the driving speed of the glass yarn) and/or the fiber opening processing force in the fiber opening step, which is preferable.

When the glass yarn of the present embodiment is used, in the process of unwinding the bobbin raw yarn on the creel and arranging the glass yarn (for example, warp yarn), it is possible to prevent defects such as the generation of fluff when rubbing against a yarn guide or the like. For this reason, there is a tendency for good quality and stable production, which is preferable. Moreover, the use of the above glass yarn tends to increase the warp-making speed, which is preferable.

(Glass thread TEX)
The TEX of the glass thread is 1-13, preferably 1.5-12, more preferably 2.0-11, even more preferably 2.5-10, or 1-7. If the TEX of the glass yarn is 13 or less, the strength of the glass yarn is weak. There is a possibility that fluff defects tend to occur easily due to interference with the conveying member of the glass cloth. On the other hand, by adjusting the degree of filament dropout within the specific range of the present embodiment, the degree of interference or the damage received during interference can be reduced, and as a result, high-quality glass cloth can be stably obtained. be able to. Since the TEX of the glass yarn is 1 or more, when the degree of filament dropout is within the specific range of the present embodiment, the glass yarn is unwound in the weaving process and then passed through a loom member such as a loop guide. Filament breakage can be suppressed when interfering with the loom members and when interfering with the conveying member of the glass cloth in the opening process.

(Breaking strength of glass thread)
The glass thread has a breaking strength of 0.50 to 0.80 N/tex. A preferable range of breaking strength is 0.53 to 0.79 N/tex, a more preferable range is 0.57 to 0.78 N/tex, and a further preferable range is 0.60 to 0.77 N/tex. If the breaking strength of the glass yarn is equal to or higher than the above lower limit, interference with the loom members when passing through the loom members such as the loop guide after the glass yarn is unwound in the weaving process, and the glass cloth in the opening process. When subjected to shear stress due to interference with the conveying member, the filament is less likely to break and fluff is less likely to occur. On the other hand, if the breaking strength of the glass yarn is equal to or less than the above upper limit, there is a tendency to suppress yarn runout or ballooning movement during the yarn conveying process until the glass yarn is unwound from the bobbin and ejected. As a result, fluff failure due to increased filament shedding or filament breakage is less likely to occur. It is presumed that this is a function and effect based on the flexibility of the glass yarn.

(Number of sliding filaments of glass yarn)
The number of sliding filaments in the glass thread is 3 or less. The preferred range for the number of sliding filaments is 2 or less, more preferably 1 or less, and still more preferably 0.

The above "180m" is
1) Length starting from the end (one end or the other end) in the length direction of the glass thread;
2) the length at any point except for the ends;
Either
As a specific example of 2) above,
2-1) A length set from a point 2 to 6 m (for example, 5 m) in the length direction from the end. If 2-1) is adopted, the number of sliding filaments can be accurately measured in accordance with the spirit of the present invention without being affected by "fraying" which tends to occur at the end of the glass yarn.

When the glass thread is wound on the bobbin, "180 m" is
3) length including at least part of the outermost or innermost circumference of the bobbin;
4) Length at any point except the outermost and innermost circumferences;
Either
As a specific example of 4) above, from the viewpoint of ease of observation,
4-1) Length set with the starting point of the second round when the outermost circumference is the first round;
4-2) The length set with the starting point of the second round when the innermost round is the first round;
is mentioned. however,
4-3) The length may be set at any point other than the starting point.

For a glass yarn with a length of 10,000 m or more, when measuring ranges of 180 m in the length direction are selected at five different locations, the number of sliding filaments in each of the five measurement ranges is The number is preferably 3 or less, more preferably 2 or less, still more preferably 1 or less, and most preferably 0.

In addition, for a glass yarn having a length of 50,000 m or more, when measuring ranges of 180 m in the length direction are selected at seven different locations, the number of sliding filaments is , preferably 3 or less, more preferably 2 or less, still more preferably 1 or less, and most preferably 0.

Also, for a glass thread having a length of 100,000 m or more, when measuring ranges of 180 m in the length direction are selected at 10 different locations, the number of sliding filaments is , preferably 3 or less, more preferably 2 or less, still more preferably 1 or less, and most preferably 0.

When measuring the number of sliding filaments, the feeding speed of the glass yarn may be increased. In the same way as weft spouting in the weaving process, measure while unwinding the glass yarn from the bobbin by air and conveying it (At this time, provide an appropriate yarn guide to prevent the spouting glass yarn from being violent) ;
etc. is possible. However, the number of sliding filaments is measured according to the method described in Examples.

Since the number of sliding filaments is less than the above range and the breaking strength is within the above range, during the transportation process from unwinding the glass yarn from the bobbin to jetting out, increased filament dropout, filament breakage, or breakage can be prevented. Coarse fluff due to tangling of filaments is less likely to occur. As a result, it is possible to stably obtain a high-quality glass cloth with few fluff-dense portions. This is because the degree and frequency of filament slippage are small within a certain range, so the degree of interference between the slippage portion and the loom members such as the loop guide or the resistance due to interference is reduced, so the damage caused by interference with the loom members is kept small. It is presumed that

In particular, as described above, the weft yarn is easily cut, and the cut filament pieces are easily entangled by the ballooning motion. On the other hand, it is presumed that by adjusting the number of fallen filaments within the above range, filament breakage or tangling of the cut filaments is suppressed. In addition, since the degree and frequency of filament slippage are small within a certain range, the degree of interference with the conveying member of the glass cloth in the opening process or the resistance due to interference is reduced, thereby suppressing damage due to interference with the conveying member. It is presumed that

The number of sliding filaments can be adjusted by the following methods, alone or in combination:
・When converging filaments discharged from multiple bushing nozzles into a single yarn bundle in the spinning process of manufacturing glass yarn, design the bushing nozzle arrangement so that the distances from the multiple bushing nozzles to the point of convergence are the same. Method;
- A method of adjusting the nozzle shape of the bushing nozzle according to the difference in the distance from the bushing nozzle to the focal point;
- A method of adjusting the temperature of the bushing nozzle according to the difference in the distance from the bushing nozzle to the focal point;
- A method of adjusting the cooling temperature in the spinning process of glass yarn production;
- A method of adjusting the cake winding tension;
- How to adjust the cake winding speed;
・How to adjust the traverse when winding the cake;
- A method of adjusting the cake winding method and the aging conditions so that the moisture content of the glass yarn and the sizing agent adhesion amount of the glass yarn become more uniform over the entire length of the glass yarn in the aging step of the cake in glass yarn production;
- A method of adjusting the shape and weight of the traveler so that the load when the glass yarn is bent is reduced in the twisting process of glass yarn production;
- A method of adjusting the fluctuation width of the number of twists per unit length to a specific range;
A method of adjusting tension fluctuations to be small while the glass thread is unwound from the cake and wound onto the bobbin;
- A method of adjusting the ballooning during twisting; and - A method of adjusting the winding angle of the glass yarn on the bobbin.

(Density of glass thread)
The density of the glass thread is preferably 2.2 g/cm ³ or more and less than 2.5 g/cm ³ , more preferably 2.2 g/cm ³ or more and less than 2.45 g/cm ³ , still more preferably 2.2 g/cm ^{3 .} 2.40 g/cm ³ or more, more preferably 2.25 g/cm ³ or more and 2.4 g/cm ³ or less.

If the density of the glass yarn is less than 2.5 g/cm ³ , during the conveying process until the glass yarn is unwound from the bobbin and jetted out, the deflection or ballooning movement in the direction perpendicular to the conveying direction tends to increase, and the loom tends to increase. Interference with members may tend to cause fluff defects. However, by adjusting the number of sliding filaments within the specific range according to the present embodiment, it is possible to suppress the generation of fluff due to interference with the loom members, thereby stably obtaining high-quality glass cloth.

In addition, if the density of the glass yarn is less than 2.5 g/cm ³ , the slackness of the glass cloth increases when subjected to a physical load such as high-pressure water spray pressure in the opening process, and the glass cloth is transported. It may easily interfere with the member, and the interference with the conveying member may tend to cause fluff defects. However, by adjusting the number of sliding filaments within the specific range of the present embodiment, it is possible to suppress the generation of fluff due to interference with the conveying member, thereby stably obtaining a high-quality glass cloth.

On the other hand, when the density of the glass yarn is 2.2 g/cm ³ or more, the conveying trajectory of the glass yarn can be stabilized. In addition, when the density of the glass yarn is 2.2 g/cm ³ or more, slackness of the glass cloth can be reduced. The density of the glass thread can be determined as the density of a 1 cm ³ block of glass.

(filament and diameter)
A glass thread is obtained by bundling a plurality of filaments and twisting them as necessary. In this case, the glass yarn is classified as a multi-glass filament, and the filament (glass filament) included in the glass yarn is classified as a mono-glass filament.
Here, the "sliding" of the filament includes not only sliding in units of one monoglass filament and sliding in units of several monoglass filaments, but also filament breakage. The number of sliding filaments can be measured by the method described in Examples.

The glass yarn is preferably a glass yarn obtained by bundling 40 to 240 monoglass filaments having an average diameter of 3.5 to 5.5, or a glass yarn having 30 to 120 monoglass filaments. By using glass yarns with an average diameter and the number of filaments in the above ranges, thicknesses equivalent to 1000, 1017, 1015, 1012, 1027, 1024, 1020, 1030, 1037, 1035, 106, 1067, and 1078 of conventional E glass cloth (IPC standard (IPC-4412B): Style 1000, 1017, 1015, 1012, 1027, 1024, 1020, 1030, 1037, 1035, 106, 1067, 1078).

(elastic modulus of glass thread)
The elastic modulus of the glass yarn is preferably 50 to 70 GPa, more preferably 50 to 63 GPa, still more preferably 53 to 63 GPa. When the elastic modulus is 50 GPa or more, the rigidity of the glass thread is improved, and fluff tends to be less likely to occur in the manufacturing process. Further, when the elastic modulus is 70 GPa or less, the brittleness resistance of the glass thread is improved, and fluff tends to be less likely to occur in the manufacturing process. Furthermore, since the elastic modulus is within the above range, the glass yarn has moderate flexibility, and when a mechanical load is applied, filament breakage or the like is less likely to occur, and fluff and weaving defects are less likely to occur. There is a tendency.

(Composition of Components of Glass Thread)
Glass thread constituent elements include 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).

The Si content of the glass yarn is preferably 40 to 60% by mass, more preferably 45 to 55% by mass, even more preferably 47 to 53% by mass, and even more preferably 48 to 52% by mass in terms of SiO ₂ .

Si is a component that forms the skeletal structure of the glass yarn, and when the Si content is 40% by mass or more, the strength of the glass yarn is more likely to be improved. As a result, breakage of the glass cloth tends to be more suppressed in subsequent processes such as the manufacturing process of the glass cloth and the manufacturing of the prepreg using the glass cloth. Moreover, when the Si content is 40% by mass or more, the dielectric constant of the glass cloth tends to be further lowered. On the other hand, when the Si content is 60% by mass or less, the viscosity during melting is further lowered in the filament production process, and as a result, glass fibers with a more homogeneous glass composition tend to be obtained. For this reason, it becomes difficult for the resulting filament to have a portion where it is easy to partially devitrify or a portion where it is difficult for air bubbles to escape partially, so that it becomes difficult for the filament to have a portion where the strength is locally weak. A glass cloth composed of glass threads obtained by using this is difficult to break. The Si content can be adjusted according to the amount of raw material used for filament production.

The B content of the glass yarn is preferably 15 to 40% by mass, more preferably 17 to 30% by mass, or 20 to 40% by mass, still more preferably 18 to 28% by mass, still more preferably in terms of B ₂ O ₃ is 19-26% by weight, even more preferably 20-25% by weight, most preferably 20.5-24% by weight.

When the B content is 15% by mass or more, the dielectric constant tends to further decrease. In addition, since the B content is 15% by mass or more, the glass cloth is improved in brittleness resistance, moderate flexibility, and flexibility, so that the glass yarn comes into contact with loom members such as yarn guides and reeds. There is a tendency that fluff is less likely to occur when it is applied. On the other hand, the B content is preferably 40% by mass or less in order to maintain the strength of the glass yarn. Moreover, when the B content is 40% by mass or less, the moisture absorption resistance is improved. The B content can be adjusted according to the amount of raw material used for filament production. In addition, if the conditions, the amount used, or the content may vary during filament production, it is possible to foresee this in advance and adjust the charging amount of the raw material.

The Al content of the glass yarn is preferably 11 to 18% by mass, more preferably 11 to 16% by mass, and still more preferably 12 to 16% by mass in terms of aluminum oxide (Al ₂ O ₃ ). When the Al content is within the above range, electrical properties and strength tend to be further improved. The Al content can be adjusted according to the amount of raw material used for filament production.

The Ca content of the glass thread is preferably 5 to 10% by mass, preferably 5 to 9% by mass, more preferably 5 to 8.5% by mass in terms of calcium oxide (CaO). When the Ca content is 5% by mass or more, the viscosity during melting tends to be lower in the filament production process, and glass fibers having a more homogeneous glass composition tend to be obtained. Moreover, when the Ca content is 10% by mass or less, the dielectric constant tends to be further improved. The Ca content can be adjusted according to the amount of raw material used for filament production.

The glass yarn may be excellent in various properties by containing predetermined amounts of Mg, P, Na, K, Ti, Zn, Fe, and F. These contents can be adjusted according to the amount of raw materials used for filament production.

Each of the above contents can be measured by ICP emission spectrometry. Specifically, the Si content and B content are determined by melting a weighed glass cloth sample with sodium carbonate, dissolving it with dilute nitric acid to a constant volume, and measuring the resulting sample by ICP emission spectrometry. Obtainable. Further, the Fe content can be obtained by dissolving a weighed glass cloth sample by an alkaline dissolution method to a constant volume, and measuring the obtained sample by ICP emission spectrometry. Furthermore, the Al content, Ca content, and Mg content were measured by thermally decomposing the weighed glass cloth sample with sulfuric acid, nitric acid, and hydrogen fluoride, and then dissolving it in dilute nitric acid to a constant volume. It can be obtained by measuring by spectroscopic analysis. As the ICP emission spectrometer, PS3520VDD II manufactured by Hitachi High-Tech Science Co., Ltd. can be used.

(Dielectric constant of glass thread)
The dielectric constant of the glass yarn is preferably 5.0 or less, more preferably 4.9 or less, even more preferably 4.8 or less, and particularly preferably 4.6 or less at a frequency of 10 GHz. The dielectric constant of glass threads can be measured, for example, by a cavity resonance method. In this specification, the dielectric constant of glass yarn refers to that at a frequency of 10 GHz unless otherwise specified.

(Glass yarn twist interval length and twist interval length difference index)
The twist interval length of the glass yarn is preferably 1.8 to 10.0 cm, more preferably 1.9 to 9.9 cm, even more preferably 1.95 to 4.0, most preferably 2.0 to 3.0 cm. 5. The minimum twist spacing length is preferably 1.8 cm, more preferably 1.9 cm, even more preferably 1.95 cm, and most preferably 2.0 cm. The maximum twist spacing length is preferably 10.0 cm, more preferably 9.9 cm, even more preferably 4.0 cm, most preferably 3.5.

In addition, the value obtained by dividing the difference between the maximum twist interval length and the minimum twist interval length of the glass yarn by the average twist interval length (twist interval length difference index) is preferably 0.7. 0.6 or less, more preferably 0.5 or less, most preferably 0.4 or less, and may exceed 0. If the twist interval length and/or the twist interval length difference index of the glass yarn are within the above numerical range, the number of filaments that slides on the outer layer of the bobbin when the glass yarn is wound around the bobbin. is likely to be 3 or less, and/or the number of sliding filaments tends to decrease over the entire length of the bobbin. Without wishing to be bound by theory, there are three possible reasons for the lower number of sliding filaments:
(i) If the twist interval length is longer than the lower limit, the torsional shear stress is kept small, so the filament is less likely to slip off;
(ii) If the twist interval length is shorter than the upper limit, the binding force between the filaments constituting the glass yarn is increased, so that the filaments are less likely to slide;
(iii) When the twist interval length difference index is smaller than the upper limit, fluctuations in the twist angle in the length direction of the glass yarn are kept small, so that the filament is less likely to slip off.
The standard deviation of the number of twists of the glass yarn is preferably 0.05 to 0.20, more preferably 0.09 to 0.18.

[Method for manufacturing glass cloth]
A third embodiment of the present invention is a method for manufacturing a glass cloth.

This embodiment is a method for manufacturing a glass cloth, which includes a step of weaving using glass yarns including a plurality of filaments as warp yarns and weft yarns.
The glass threads used are, as explained above,
(i) TEX is 1 to 13;
(ii) The breaking strength is 0.50 to 0.80 N/tex, and (iii) The number of filaments that have slipped (the number of filaments that have slid at least twice the average yarn width when measuring 180 m is 3 or less.

Specifically, such a manufacturing method includes a glass yarn adjustment step of adjusting the glass yarn so that the number of sliding filaments is a specific number or less, a weaving step of weaving the adjusted glass yarn to obtain a glass cloth, and a fiber opening step of opening the glass threads of the glass cloth. The method for producing the glass cloth may optionally include a desizing step for removing the sizing agent adhering to the glass threads of the glass cloth, and a surface treatment step using a silane coupling agent.
Each step in the glass cloth manufacturing method will be described in more detail below.

(Glass yarn adjustment process)
The glass yarn adjusting step is a step of adjusting the glass yarn so that the number of sliding filaments is 3 or less. More specifically, in the glass yarn adjustment step, if the number of sliding filaments is within the above range, the glass yarn is used in the subsequent weaving process, and if it is outside the range, the use of the glass yarn as the glass yarn is prohibited. do.

A method for measuring the number of slipping filaments is a method of observing the yarn width and the slipped filaments with a displacement meter of a light projection type such as laser light, LED light, etc. while conveying the glass yarn; A method of observing the yarn width and the slipped filament while observing the shape of the image;

(Weaving process)
The weaving process is a process of weaving glass threads to obtain a glass cloth. Examples of the weave structure of the glass cloth include plain weave, Nanako weave, satin weave, and twill weave. Among these, the plain weave structure is more preferable.

In an example of the weaving process in the manufacturing method of the present embodiment, the warp yarns drawn in parallel are opened vertically by an air jet loom method, and the yarn supplied from the weft storage device is jetted from the nozzle into the openings. Weaving can be performed by sending out as a weft and passing it through.

In this weaving process, in the glass yarn ejection process of unwinding the glass yarn to be the weft from the bobbin and ejecting the weft through the storage device,
Because the glass yarn is conveyed with interference with loom members such as yarn guides while accompanying movement in a direction different from the traveling direction such as ballooning movement; or
Since the ejection and stop of the weft are repeated in units of the length of one weft, the weft is conveyed with interference with loom members such as yarn guides while the tension fluctuates;
It is difficult to suppress the damage caused by the above-mentioned interference to a weft yarn having a large number of sliding filaments, and the resulting glass cloth may have fluff or weaving defects.

On the other hand, in the present embodiment, by using a glass yarn having a sliding filament number within a specific range, the occurrence of fluff or weaving defects is suppressed when weaving the weft yarn, thereby improving the quality of the glass cloth. In-plane uniformity and lot-to-lot uniformity can be improved. The weaving method is not limited to the air jet loom method, and may be a water jet loom method or a shuttle method.

The density of warps and wefts forming the glass cloth is preferably 30 to 120/25 mm, more preferably 40 to 110/25 mm, still more preferably 45 to 105/25 mm. The warp driving density can be controlled by adjusting the spacing between the warp threads drawn in parallel, and the weft driving density is controlled by the number of weft jets per unit time from the nozzle and the warp flow speed. can do.

(Opening process)
The opening step is a step of opening the glass threads of the glass cloth. The opening method includes, for example, a method of opening with spray water (high-pressure water opening), vibro washer, ultrasonic water, mangle, or the like.

The thickness of the glass cloth finally obtained through the fiber opening step and the like is preferably 5 to 60 μm, more preferably 7 to 55 μm, still more preferably 9 to 50 μm or 10 to 50 μm. When the thickness of the glass cloth is within the above range, there is a tendency to obtain a thin glass cloth with relatively high strength. The cloth weight (basis weight) of the glass cloth finally obtained through the fiber opening step and the like is preferably 5 to 55 g/m ² , more preferably 6 to 50 g/m ² , and still more preferably 7 to 48 g/m ² . be.

(Degluing process)
The desizing process is a process for removing the sizing agent adhering to the glass threads of the glass cloth. Examples of the desizing method include a method of removing the sizing agent by heating.

(Surface treatment process)
The surface treatment step is a step of surface-treating the glass cloth with a silane coupling agent. Examples of the surface treatment method include a method in which a surface treatment agent containing a silane coupling agent is brought into contact with glass cloth and dried. The contact of the surface treatment agent with the glass cloth includes a method of penetrating the glass cloth into the surface treatment agent; a method of applying the surface treatment agent to the glass cloth using a roll coater, a die coater, a gravure coater, or the like; is mentioned. The method for drying the surface treatment agent is not particularly limited, but examples thereof include hot air drying and a drying method using electromagnetic waves.

[Prepreg]
The prepreg has the glass cloth obtained as described above and the matrix resin composition impregnated in the glass cloth. A prepreg having the above glass cloth has little variation in quality and a high yield of the final product.

A prepreg can be manufactured according to a conventional method. For example, after impregnating a glass cloth with a varnish obtained by diluting a matrix resin such as an epoxy resin with an organic solvent, the organic solvent is volatilized in a drying oven to bring the thermosetting resin into a B-stage state (semi-cured state). It can be produced by curing to

As the matrix resin composition, thermosetting resins such as bismaleimide resins, cyanate ester resins, unsaturated polyester resins, polyimide resins, BT resins, functionalized polyphenylene ether resins; polyphenylene ether resins, Thermoplastic resins such as polyetherimide resins, wholly aromatic polyester liquid crystal polymers (LCP), polybutadiene, and fluororesins; 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 matrix resin composition.

In addition, the matrix resin composition contains inorganic fillers such as silica and aluminum hydroxide in the resin; flame retardants such as bromine-based, phosphorus-based, and metal hydroxides; other silane coupling agents; heat stabilizers; a UV absorber; a pigment; a coloring agent; a lubricant and the like.

[Printed wiring board]
A printed wiring board preferably comprises the prepreg. A printed wiring board comprising the prepreg has little variation in quality, and the yield of the final product is high. In addition, since the printed wiring board comprising the prepreg has excellent dielectric properties and excellent moisture absorption resistance, it is possible to achieve the effect that the fluctuation of the dielectric constant is small in the influence of the use environment, especially in a high humidity environment.

Hereinafter, the present invention will be described more specifically using examples and comparative examples.

[Physical properties of glass thread and glass cloth]
Physical properties of glass yarn and glass cloth, specifically, thickness of glass cloth, average diameter of filaments constituting glass yarn, TEX of glass yarn, breaking strength (tensile strength) of glass yarn, driving of warp and weft Density (woven density) was measured according to JIS R3420.

[Twist interval length, twist interval length difference index]
Using a twist detector (manufactured by Technos), the number of twists of 50 cm of glass yarn was measured, and the length per twist interval was calculated by dividing by the number of twists resulting in a measured length of 50 cm. By this method, the number of twists per 50 cm was repeatedly measured at 30 points, the length per twist interval was calculated, and the length data per twist interval was calculated at 30 points. The obtained 30 pieces of length data per twist interval were averaged to obtain the twist interval length.

In addition, using the average value, maximum value, and minimum value of the obtained 30 points of twist interval length data, the ratio of the difference between the maximum value and the minimum value of the twist interval length to the average value of the twist interval length , the twist interval length difference index was determined by the following formula (1).
Twist interval length difference index={(maximum twist interval length−minimum twist interval length)/average twist interval length}×100 (1)

[Standard deviation of twist number]
Using a twist detector (manufactured by Technos), the number of twists of 50 cm of glass yarn was measured and converted into the number of twists per 25 mm. By this method, the number of twists per 25 mm was repeatedly measured at 30 points, and the standard deviation of the obtained 30 points of twist number data was determined.

[Elastic modulus]
The elastic modulus of the glass yarn was measured by the pulse-echo overlap method using a glass bulk obtained by melting and cooling the glass yarn as a test piece.

[Number of sliding filaments]
While conveying the glass yarn at a speed of 1 m / min, using an LED camera type dimension measuring device (HIGH ACCURACY CMOS MICROMETER LS-9006MR / manufactured by Keyence), while observing the projected shape of the glass yarn on the monitor The width was measured continuously. The yarn width of 180 m of glass yarn was measured, and the average value of the yarn width of the glass yarn was calculated from the obtained yarn width data. In addition, count the number of cases where filament slippage is observed from the center of the yarn width to more than twice the yarn width, and the total is the "sliding filament number", that is, "twice the yarn width average value at the time of 180m measurement. The number of filaments that slipped more than

Here, the yarn width measurement by the LED camera type dimension measuring device is performed under the condition that 1934 measured values per 1 m can be obtained, and if an error occurs due to the LED not being focused (-9999 value is displayed ), the measured values were deleted and the average value of the yarn width and/or the number of sliding filaments was calculated.

The tension acting on the glass yarn when the glass yarn is conveyed is the tension measured with a tension meter (Control instruments ETPB-100-C0585 manufactured by SCHMIDT), and is 0.12 to 0.18 N. there were.

[Bobbin appearance inspection (fluff inspection)]
The appearance of the bobbin wound with the glass thread was visually inspected, and the number of fluffs detected (the number of fluffs) was counted. This inspection was performed 50 times, and the average number of fluff was calculated.

[Fuzz inspection of glass yarn for evaluation by applying load to glass yarn]
Using a fluff inspection device manufactured by NIHON KAGAKU ENG, while conveying the glass yarn at a speed of 1 m/min, the glass yarn is passed through a model reed with a reed spacing distance of 0.35 mm that reciprocates 450 times per minute. , the number of fluff generated per 180 m was counted with a sensor. Further, the reciprocating speed of the model reed was set to 100 reciprocating/min, and the number of fluff generated per 180 m was similarly counted by the sensor.

[Evaluation: fluff quality of glass cloth]
The effect of glass thread quality (for example, the number of sliding filaments) on the fluff quality of glass cloth was investigated. As standard conditions for glass cloth production, the rotation speed of the loom was set at 450 rpm, and the opening treatment was performed by high-pressure water spray. Furthermore, the number of rotations of the loom was increased (550, 600 rpm) for the purpose of improving productivity, and the strength of high-pressure water spray was increased for the purpose of improving characteristics.

The fluff quality of the glass cloths obtained in Examples, Comparative Examples and Reference Examples was evaluated by visual inspection. Using a glass cloth inspection machine, the fluff quality of the glass cloth was visually evaluated while conveying the glass cloth at a speed of 10 m/min. Here, in the conventional visual inspection, light from a halogen lamp is applied to the glass cloth in a direction perpendicular to it, and fluff and weave defects are observed as portions where the light is reflected. However, in order to observe filament cut fluff with a length of less than 1 mm with high sensitivity, a visual inspection was performed by irradiating a white LED light from the edge side of the glass cloth in a parallel direction to the glass cloth surface. Fluff was scattered over the entire surface of the inspection plate-shaped glass cloth, and therefore, the occurrence of fluff that was observed to be shiny over the entire surface of the glass cloth was defined as a full-surface fluff defect. Observation of fluffing on the whole surface with an optical microscope revealed that a large amount of fluffing was caused by broken filaments of approximately 200 μm to 1000 μm.

With a measurement length of 500 m as a target, if there is fluff on the entire surface within a range of 1 m in the length direction of the glass cloth, the number of defects is counted as 1, and the following formula:
Demerit rate (%) = (total number of defects counted / 500) x 100
According to, the deduction rate was calculated.

[Evaluation: Evaluation of impregnation property of glass cloth]
A bisphenol A type epoxy resin was dissolved in benzyl alcohol in an environment of 23±2° C. to prepare a varnish for impregnation evaluation having a viscosity of 230±5 mPa·s. Next, the glass cloth test piece was immersed in the varnish for impregnation evaluation, and while irradiating with light from the side, the impregnation of the glass cloth with the varnish for evaluation of impregnation was observed with an optical microscope. . Five minutes after the glass cloth test piece was immersed in the impregnability evaluation varnish, the number of voids (parts not impregnated with the impregnation evaluation varnish) was counted. At this time, the visual field range of the glass cloth observed with an optical microscope was about 6.5 mm in the warp direction and about 9 mm in the weft direction.

[Examples and Comparative Examples; glass yarn]
[Test Example 1]
Glass threads A to N (low dielectric glass threads, density 2.3 g/cm ³ , elastic modulus 61 GPa) and O to Q (low dielectric glass threads, density 2.3 g/cm ³ , elasticity) wound on bobbins (modulus 56 GPa), R (E glass yarn, density 2.6 g/cm ³ , elastic modulus 74 _GPa ). Filament count was measured.

[Test Example 2]
Next, the number of slid-off filaments was measured using a point _T500 at which 500 m of the glass yarn was further unwound from the bobbin, that is, a point 500 m in the length direction from the above-described starting point _T0 .

[Test Example 3]
Further unwinding the glass yarn from the bobbin according to Test Examples 1 and 2 above,
A point 1,000 m in the length direction from the starting point T ₀ is set as the starting point T _1,000 ;
A point 2,000 m in the length direction from the above starting point T ₀ is defined as the starting point T _2,000 ;
A point 5,000 m in the length direction from the starting point T ₀ is set as the starting point T _5,000 ;
A point 7,000 m in the length direction from the starting point T ₀ is set as the starting point T _7,000 ;
A point 9,000 m in the length direction from the starting point T ₀ is defined as the starting point T _9,000 ;
A point 10,000 m in the length direction from the above starting point T ₀ is defined as the starting point T _10,000 ;
A point 20,000 m in the length direction from the above starting point T ₀ is defined as the starting point T _20,000 ;
A point 30,000 m in the length direction from the starting point T ₀ is defined as the starting point T _30,000 ;
A point 40,000 m in the length direction from the starting point T ₀ is defined as the starting point T _40,000 ;
A point 50,000 m in the length direction from the starting point T ₀ is set as the starting point T _50,000 ;
A point 60,000 m in the length direction from the above starting point T ₀ is defined as the starting point T _60,000 ;
A point 70,000 m in the length direction from the starting point T ₀ is defined as the starting point T _70,000 ;
A point 80,000 m in the length direction from the starting point T ₀ is set as the starting point T _80,000 ;
A point 100,000 m in the length direction from the starting point T ₀ is defined as the starting point T _100,000 ;
A point 120,000 m in the length direction from the starting point T ₀ is defined as the starting point T _120,000 ;
The number of sliding filaments was measured. Table 1 shows the results obtained.

The glass yarns A to C, G, H, J, K, O, and P of the examples, which have a small twist interval length difference index and are evenly and gently twisted, have a sliding filament number evaluated in the bobbin outer layer part. There were 3 or less.
Starting point T ₀ ; Starting point T ₅₀₀ ; Starting point T _1,000 ; Starting point T _{2,000 ;} Starting point T _5,000 ; Starting point T _7,000 ; The number of sliding filaments was 3 or less. As a result, for a glass thread having a length of 10,000 m or more, when measuring ranges of 180 m in the length direction are selected at five different locations, the number of sliding filaments is It was confirmed that each of the above corresponds to 3 or less.

Even for glass yarns having a length of 50,000 m or more, according to the same principle as above, when measuring ranges of 180 m in the length direction are selected at seven different locations, the number of filaments that slide out is It was confirmed that there were 3 or less in each of the above 7 measurement ranges.

Even for glass yarns having a length of 100,000 m or more, according to the same principle as above, when measuring ranges of 180 m in the length direction are selected at 10 different locations, the number of filaments that slide out is It was confirmed that there were 3 or less in each of the above 10 measurement ranges.

On the other hand, the glass yarns D to F, I, L to N, Q, and R of the comparative examples, which had a large twist interval length difference index, had 4 or more sliding filaments in the predetermined measurement range.

[Example 1]
Low dielectric glass yarn (TEX 4.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% by mass in terms of MgO, 23.3% by mass in terms of B ₂ O ₃ , 0.1% by mass in terms of P ₂ O ₃ ) for the warp and weft, and the loom rotation speed of the air jet loom is 450 rpm ( A glass cloth green fabric with a warp weaving density of 65/25 mm and a weft weaving density of 67/25 mm was obtained under the conditions of a weft weaving speed of 450/min.
In the table, as shown in the item "Number of filaments slid measured from starting point _T0 ", in Example 1, the number of filaments that slid more than twice the yarn width average value when measuring 180 m from the starting point _T0 A glass thread with a value of 0 was used.

Next, desizing is performed by heating the glass cloth greige fabric, high-pressure water opening is performed with a spray adjusted to a water pressure of 5.0 ± 0.1 kg / cm ² , and then a silane coupling agent is applied to the surface. A glass cloth having a thickness of 29 μm was produced by processing.

[Example 2]
Low dielectric glass yarn (TEX 4.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% by mass as MgO, 23.3% by mass as B ₂ O ₃ , 0.1% by mass as P ₂ O ₃ ). of glass cloth was produced.

[Example 3]
Low dielectric glass yarn (TEX 4.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% by mass as MgO, 23.3% by mass as B ₂ O ₃ , 0.1% by mass as P ₂ O ₃ ). of glass cloth was produced.

[Example 4]
Low dielectric glass yarn (TEX 4.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% by mass as MgO, 23.3% by mass as B ₂ O ₃ , 0.1% by mass as P ₂ O ₃ ). of glass cloth was produced.

[Comparative Example 1]
Low dielectric glass yarn (TEX 4.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% by mass as MgO, 23.3% by mass as B ₂ O ₃ , 0.1% by mass as P ₂ O ₃ ). of glass cloth was produced.

[Comparative Example 2]
Low dielectric glass yarn (TEX 4.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% by mass as MgO, 23.3% by mass as B ₂ O ₃ , 0.1% by mass as P ₂ O ₃ ). of glass cloth was produced.

[Comparative Example 3]
Low dielectric glass yarn (TEX 4.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% by mass as MgO, 23.3% by mass as B ₂ O ₃ , 0.1% by mass as P ₂ O ₃ ). of glass cloth was produced.

[Example 5]
A glass cloth having a thickness of 29 μm was produced in the same manner as in Example 1, except that the rotation speed of the loom in the air jet loom was 550 rpm.

[Example 6]
A glass cloth having a thickness of 29 μm was produced in the same manner as in Example 3, except that the rotation speed of the loom in the air jet loom was 550 rpm.

[Comparative Example 4]
A glass cloth having a thickness of 29 μm was produced in the same manner as in Comparative Example 1, except that the rotation speed of the loom in the air jet loom was 550 rpm.

[Example 7]
A glass cloth having a thickness of 29 μm was produced in the same manner as in Example 1, except that the rotation speed of the loom in the air jet loom was 600 rpm.

[Example 8]
A glass cloth having a thickness of 29 μm was produced in the same manner as in Example 3, except that the rotation speed of the loom in the air jet loom was 600 rpm.

[Comparative Example 5]
A glass cloth having a thickness of 29 μm was produced in the same manner as in Comparative Example 1, except that the rotation speed of the loom in the air jet loom was 600 rpm.

[Example 9]
A glass cloth having a thickness of 29 μm was prepared in the same manner as in Example 1, except that the opening strength was increased by increasing the water pressure of the high-pressure water spray in the opening process to 12.0±0.1 kg/cm ^{2 .} made.

[Example 10]
A glass cloth having a thickness of 29 μm was prepared in the same manner as in Example 3, except that the opening strength was increased by increasing the water pressure of the high-pressure water spray in the opening process to 12.0±0.1 kg/cm ^{2 .} made.

[Comparative Example 6]
A glass cloth having a thickness of 29 μm was prepared in the same manner as in Comparative Example 1, except that the opening strength was increased by increasing the water pressure of the high-pressure water spray in the opening process to 12.0±0.1 kg/cm ^{2 .} made.

[Comparative Example 7]
A glass cloth having a thickness of 29 μm was prepared in the same manner as in Comparative Example 2, except that the opening strength was increased by increasing the water pressure of the high-pressure water spray in the opening process to 12.0±0.1 kg/cm ^{2 .} made.

[Comparative Example 8]
A glass cloth having a thickness of 29 μm was prepared in the same manner as in Comparative Example 3, except that the opening strength was increased by increasing the water pressure of the high-pressure water spray in the opening process to 12.0±0.1 kg/cm ^{2 .} made.

[Example 11]
Low dielectric glass yarn (TEX 2.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% by mass in terms of MgO, 23.3% by mass in terms of B ₂ O ₃ , 0.1% by mass in terms of P ₂ O ₃ ) for the warp and weft, and the loom rotation speed of the air jet loom is 450 rpm ( A glass cloth green fabric with a warp weaving density of 74/25 mm and a weft weaving density of 74/25 mm was obtained under the conditions of a weft weaving speed of 450/min.

Next, desizing is performed by heating the glass cloth green fabric, high-pressure water opening is performed with a spray adjusted to a water pressure of 4.0 ± 0.1 kg / cm ² , and then a silane coupling agent is applied to the surface. A glass cloth having a thickness of 21 μm was produced by processing.

[Example 12]
Low dielectric glass yarn (TEX 2.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% _{by mass in terms of MgO, 23.3% by mass in terms of B2O3 , 0.1 %} by mass in terms of P2O3). of glass cloth was produced.

[Comparative Example 9]
Low dielectric glass yarn (TEX 2.9, number of filaments: 100, elastic modulus: 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , 8.3 mass% in terms of CaO) listed in the table below. 1% by mass, 0.3% _{by mass in terms of MgO, 23.3% by mass in terms of B2O3 , 0.1 %} by mass in terms of P2O3). of glass cloth was produced.

[Example 13]
A glass cloth having a thickness of 21 μm was prepared in the same manner as in Example 11, except that the water pressure of the high-pressure water spray in the fiber opening process was increased to 10.0±0.1 kg/cm ² to increase the strength of the fiber opening. made.

[Comparative Example 10]
Glass cloth having a thickness of 21 μm was prepared in the same manner as in Comparative Example 9, except that the opening strength was increased by increasing the water pressure of the high-pressure water spray in the opening process to 10.0±0.1 kg/cm ^{2 .} made.

[Example 14]
Low dielectric glass yarn (TEX 9.8, number of filaments: 200, elastic modulus: 61 GPa, glass composition: 51.2% by mass in terms of _SiO2 , _14.3 % by mass in terms of _Al2O3 , 8.3% in terms of CaO) 1% by mass, 0.3% by mass in terms of MgO, 23.3% by mass in terms of B ₂ O ₃ , 0.1% by mass in terms of P ₂ O ₃ ) for the warp and weft, and the loom rotation speed of the air jet loom is 450 rpm ( A glass cloth green fabric with a warp weaving density of 52.5/25 mm and a weft weaving density of 52.5/25 mm was obtained under the conditions of a weft weaving speed of 450/min.

Next, desizing is performed by heating the glass cloth greige, high-pressure water opening is performed with a spray adjusted to a water pressure of 6.0 ± 0.1 kg / cm ² , and then a silane coupling agent is applied to the surface. After treatment, a glass cloth having a thickness of 46 μm was produced.

[Example 15]
Low dielectric glass yarn (TEX 9.8, number of filaments: 200, elastic modulus: 61 GPa, glass composition: 51.2% by mass in terms of _SiO2 , _14.3 % by mass in terms of _Al2O3 , 8.3% in terms of CaO) 1% by mass, 0.3% by mass as MgO, _23.3 % by mass as _{B2O3 , 0.1} % by mass as P2O3). of glass cloth was produced.

[Comparative Example 11]
Low dielectric glass yarn (TEX 9.8, number of filaments: 200, elastic modulus: 61 GPa, glass composition: 51.2% by mass in terms of _SiO2 , _14.3 % by mass in terms of _Al2O3 , 8.3% in terms of CaO) 1% by mass, 0.3% by mass as MgO, _23.3 % by mass as _{B2O3 , 0.1} % by mass as P2O3). of glass cloth was produced.

[Example 16]
A glass cloth having a thickness of 46 μm was prepared in the same manner as in Example 14, except that the water pressure of the high-pressure water spray in the fiber opening process was increased to 12.0±0.1 kg/cm ² to increase the strength of the fiber opening. made.

[Comparative Example 12]
A glass cloth having a thickness of 46 μm was prepared in the same manner as in Comparative Example 11, except that the opening strength was increased by increasing the water pressure of the high-pressure water spray in the opening process to 12.0±0.1 kg/cm ^{2 .} made.

[Example 17]
Low dielectric glass yarn (TEX 4.8, number of filaments: 100, elastic modulus: 56 GPa, glass composition: 49.8 mass% in terms of _SiO2 , _16.8 mass% in terms of _Al2O3 , 3.8 mass% in terms of CaO) listed in the table below. 1% by mass, 0.1% by mass in terms of MgO, 23.9% by mass in terms of B ₂ O ₃ , 4.0% by mass in terms of P ₂ O ₃ ) for the warp and weft, and the loom rotation speed of the air jet loom is 450 rpm ( A glass cloth green fabric with a warp weaving density of 65/25 mm and a weft weaving density of 67/25 mm was obtained under the conditions of a weft weaving speed of 450/min.

Next, desizing is performed by heating the glass cloth greige fabric, high-pressure water opening is performed with a spray adjusted to a water pressure of 5.0 ± 0.1 kg / cm ² , and then a silane coupling agent is applied to the surface. After treatment, a glass cloth having a thickness of 31 μm was produced.

[Example 18]
Low dielectric glass yarn (TEX 4.8, number of filaments: 100, elastic modulus: 56 GPa, glass composition: 49.8 mass% in terms of _SiO2 , _16.8 mass% in terms of _Al2O3 , 3.8 mass% in terms of CaO) listed in the table below. 1% by mass, 0.1% by mass in terms of MgO, _23.9 % by mass in terms of _B2O3 , _4.0 % by mass in terms of P2O3 ₎ . of glass cloth was produced.

[Comparative Example 13]
Low dielectric glass yarn (TEX 4.8, number of filaments: 100, elastic modulus: 56 GPa, glass composition: 49.8 mass% in terms of _SiO2 , _16.8 mass% in terms of _Al2O3 , 3.8 mass% in terms of CaO) listed in the table below. 1% by mass, 0.1% by mass as MgO, 23.9% by mass as B ₂ O ₃ , 4.0% by mass as P ₂ O ₃ ). of glass cloth was produced.

[Example 19]
Glass cloth with a thickness of 31 μm was prepared in the same manner as in Example 17, except that the water pressure of the high-pressure water spray in the fiber opening process was increased to 12.0±0.1 kg/cm ² to increase the strength of the fiber opening. made.

[Comparative Example 14]
A glass cloth having a thickness of 31 μm was prepared in the same manner as in Comparative Example 13, except that the opening strength was increased by increasing the water pressure of the high-pressure water spray in the opening process to 12.0±0.1 kg/cm ^{2 .} made.

[Reference Example 1a]
Low dielectric glass yarn with a number of sliding filaments of 5 to 10 (TEX 14.6, number of filaments 200, elastic modulus 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , CaO conversion 8.1 mass%, MgO conversion 0.3 mass%, B ₂ O ₃ conversion 23.3 mass%, P ₂ O ₃ conversion 0.1 mass%) is used for the warp and weft, and the air jet loom loom A glass cloth green fabric with a warp weaving density of 59/25 mm and a weft weaving density of 61/25 mm was obtained under the condition of a rotation speed of 450 rpm (weft weaving speed of 450/min).

Next, desizing is performed by heating the glass cloth green fabric, high-pressure water opening is performed with a spray adjusted to a water pressure of 7.0 ± 0.1 kg / cm ² , and then a silane coupling agent is applied to the surface. After treatment, a glass cloth having a thickness of 73 μm was produced.

[Reference Example 1b]
A glass cloth having a thickness of 73 μm was prepared in the same manner as in Reference Example 1a, except that the water pressure of the high-pressure water spray in the fiber opening process was increased to 12.0±0.1 kg/cm ² to increase the strength of the fiber opening. made.

[Reference Example 2a]
Low dielectric glass yarn with 5 to 10 sliding filaments (TEX 19.4, 200 filaments, elastic modulus 61 GPa, glass composition: 51.2 mass% in terms of _SiO2 , _14.3 mass% in terms of _Al2O3 , CaO conversion 8.1 mass%, MgO conversion 0.3 mass%, B ₂ O ₃ conversion 23.3 mass%, P ₂ O ₃ conversion 0.1 mass%) is used for the warp and weft, and the air jet loom loom A glass cloth green fabric with a warp weaving density of 60/25 mm and a weft weaving density of 57/25 mm was obtained under the condition of a rotation speed of 450 rpm (weft weaving speed of 450/min).

Next, desizing is performed by heating the glass cloth green fabric, high-pressure water opening is performed with a spray adjusted to a water pressure of 7.0 ± 0.1 kg / cm ² , and then a silane coupling agent is applied to the surface. A glass cloth having a thickness of 89 μm was produced by processing.

[Reference Example 2b]
A glass cloth having a thickness of 89 μm was prepared in the same manner as in Reference Example 2a, except that the water pressure of the high-pressure water spray in the fiber-spreading treatment was increased to 12.0±0.1 kg/cm ² to increase the strength of the fiber-spreading. made.

[Reference Example 3a]
E glass yarn with a sliding filament number of 5 to 10 (TEX 5.5, filament number 100, elastic modulus 74 GPa, glass composition: 53.1 mass% in terms of _SiO2 , _15.3 mass% in terms of _Al2O3 , CaO 21.0% by mass in terms of MgO, 1.9% by mass in terms of MgO, 8.0% by mass in terms of B ₂ O ₃ , < 0.1% by mass in terms of P ₂ O ₃ ) for the warp and weft, and an air jet loom loom A glass cloth green fabric with a warp weaving density of 65/25 mm and a weft weaving density of 67/25 mm was obtained under the condition of a rotation speed of 450 rpm (weft weaving speed of 450/min).

Next, desizing is performed by heating the glass cloth greige fabric, high-pressure water opening is performed with a spray adjusted to a water pressure of 5.0 ± 0.1 kg / cm ² , and then a silane coupling agent is applied to the surface. A glass cloth having a thickness of 29 μm was produced by processing.

[Reference Example 3b]
A glass cloth having a thickness of 89 μm was prepared in the same manner as in Reference Example 3a, except that the water pressure of the high-pressure water spray in the fiber opening process was increased to 12.0±0.1 kg/cm ² to increase the strength of the fiber opening. made.

The table below shows the evaluation results of the glass yarns and the glass cloths in the above examples, comparative examples, and reference examples. In the table, the notation of "±0.1 (kg/cm ² )" is omitted in the item of "water pressure (kg/cm ² ) at the time of high-pressure water opening".

In Examples 1 to 4, Examples 11 and 12, Examples 14 and 15, and Examples 17 and 18, glass cloths with excellent fluff quality were obtained. Since the glass yarn used in these examples has a number of slidable filaments measured from the starting point _T0 of 3 or less, it is inferred that the number of slidable filaments is small throughout the glass yarn wound on the bobbin. be done. It was confirmed that a glass cloth having excellent fluff quality can be obtained by using such a glass thread.

In Examples 5 to 8, even if the rotation speed of the loom was increased from 450 rpm to 550 rpm or 600 rpm in order to increase the productivity in the weaving process, the quality of the fluff did not deteriorate significantly, and a glass cloth with relatively good fluff quality was obtained. was taken.

In Examples 9, 10, 13, 16, and 19, by increasing the water pressure of the high-pressure water spray, a low dielectric glass cloth with improved impregnation while maintaining relatively good fluff quality was obtained.

On the other hand, in Comparative Examples 1 to 3, Comparative Example 9, Comparative Example 11, and Comparative Example 13, the obtained glass cloths were inferior in fluff quality.

Furthermore, in Comparative Examples 4 to 8, 10, 12, and 14, the fluff quality was improved by increasing the rotation speed of the loom from 450 rpm to 550 rpm or 600 rpm in the weaving process, or by increasing the water pressure of the high-pressure water spray in the opening process. A glass cloth with a significantly inferior value was obtained.

In Reference Examples 1 (a, b) and 2 (a, b), the thicknesses were 73 μm and 89 μm, respectively, which were not as thin as the glass cloths of Examples 1-16.

In Reference Example 3 (a, b) using the E glass yarn, a glass cloth with relatively good fluff quality was obtained. In low dielectric glass yarns with the same TEX, when the number of sliding filaments is large, the quality of fluff tends to deteriorate due to the increase in the spray pressure of the high-pressure water spray (Comparative Examples 1 to 3, 6 to 8). Judging from the results of Reference Example 3, such a tendency was not confirmed for the E-glass yarn.

In Examples 1 to 4 and Comparative Examples 1 to 3, the "number of sliding filaments" was higher than the "bobbin appearance inspection" and the "number of fluff generated by applying a load to the glass thread". Results reflected in quality were obtained.

Claims (31)

A glass cloth woven using glass yarns containing a plurality of glass filaments as warps and wefts,
A white LED light is irradiated along the cloth surface for 500 m in the length direction of the glass cloth, and observation is performed every 1 m in the length direction. then the following expression:
Demerit rate (%) = (total number of defects counted / 500) x 100
A glass cloth with a demerit rate of 0 to 3.5%. 2. The glass cloth according to claim 1, wherein said entire surface fluff includes fluff of 200 to 1000 μm due to broken filaments observed on said cloth surface with an optical microscope. The glass cloth according to claim 1, wherein the glass cloth has a thickness of 10 to 50 µm. The following conditions:
(i) TEX is 1 to 13;
(ii) The breaking strength is 0.50 to 0.80 N / tex, and (iii) The number of filaments that have slipped more than twice the average yarn width when measuring 180 m is 3 or less.
2. The glass cloth according to claim 1, comprising said glass threads satisfying: The glass cloth according to claim 1, comprising the glass yarn having a twist interval length of 1.8 to 10.0 cm. The value obtained by dividing the difference between the maximum twist interval length and the minimum twist interval length of the glass yarn by the average twist interval length (twist interval length difference index) is 0.7 or less. , the glass cloth according to claim 1, comprising the glass thread. For the glass thread having a length of 10,000 m or more,
When measuring ranges of 180 m in the length direction are selected at five different locations, the number of filaments that have slipped at least twice the yarn width average value is 3 or less in each of the five measurement ranges. , The glass cloth according to any one of claims 1 to 6. For the glass thread having a length of 50,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 7 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 7 measurement ranges. , The glass cloth according to any one of claims 1 to 6. For the glass thread having a length of 100,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 10 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 10 measurement ranges. , The glass cloth according to any one of claims 1 to 6. A method for producing a glass cloth, comprising a step of weaving using glass yarns containing a plurality of glass filaments as warps and wefts,
(i) the glass yarn has a TEX of 1 to 13;
(ii) the glass yarn has a breaking strength of 0.50 to 0.80 N/tex, and (iii) the number of filaments that have slipped at least twice the average yarn width when measured at 180 m is 3 or less. ,
A method for manufacturing a glass cloth. The method for producing a glass cloth according to claim 10, wherein the TEX of the glass yarn is 1-7. The method for producing a glass cloth according to claim 10, wherein the number of monoglass filaments constituting the glass yarn is 30 to 120. The method for producing a glass cloth according to claim 10, wherein the glass yarn has a twist interval length of 1.8 to 10.0 cm. The value obtained by dividing the difference between the maximum twist interval length and the minimum twist interval length of the glass yarn by the average twist interval length (twist interval length difference index) is 0.7 or less. 11. The method for manufacturing the glass cloth according to claim 10. The method for producing a glass cloth according to claim 10, wherein the glass thread has a density of 2.2 g/cm ³ or more and less than 2.5 g/cm ³ . The method for producing a glass cloth according to claim 10, wherein the elastic modulus of the glass yarn is 50 to 70 GPa. The method for producing a glass cloth according to claim 10, wherein the elastic modulus of the glass yarn is 50 to 63 GPa. For the glass thread having a length of 10,000 m or more,
When measuring ranges of 180 m in the length direction are selected at five different locations, the number of filaments that have slipped at least twice the yarn width average value is 3 or less in each of the five measurement ranges. , The method for producing a glass cloth according to any one of claims 10 to 17. For the glass thread having a length of 50,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 7 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 7 measurement ranges. , The method for producing a glass cloth according to any one of claims 10 to 17. For the glass thread having a length of 100,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 10 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 10 measurement ranges. , The method for producing a glass cloth according to any one of claims 10 to 17. (i) TEX is 1 to 13;
(ii) breaking strength is 0.50 to 0.80 N / tex, and (iii) the number of filaments that have slipped more than twice the yarn width average value when measuring 180 m is 3 or less.
glass thread. The glass yarn according to claim 21, wherein the TEX is 1-7. The glass yarn according to claim 21, wherein the number of monoglass filaments constituting the glass yarn is 30 to 120. The glass yarn according to claim 21, wherein the twist spacing length is 1.8 to 10.0 cm. According to claim 21, the value obtained by dividing the difference between the maximum twist interval length and the minimum twist interval length by the average twist interval length (twist interval length difference index) is 0.7 or less. Glass thread as described. The glass thread according to claim 21, having a density of 2.2 g/cm ³ or more and less than 2.5 g/cm ³ . The glass yarn according to claim 21, which has an elastic modulus of 50 to 70 GPa. The glass yarn according to claim 21, which has an elastic modulus of 50 to 63 GPa. For the glass thread having a length of 10,000 m or more,
When measuring ranges of 180 m in the length direction are selected at five different locations, the number of filaments that have slipped at least twice the yarn width average value is 3 or less in each of the five measurement ranges. , The glass yarn according to any one of claims 21 to 28. For the glass thread having a length of 50,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 7 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 7 measurement ranges. , The glass yarn according to any one of claims 21 to 28. For the glass thread having a length of 100,000 m or more,
When measuring ranges of 180 m in the length direction are selected at 10 different locations, the number of filaments that have slipped more than twice the yarn width average value is 3 or less in each of the 10 measurement ranges. , The glass yarn according to any one of claims 21 to 28.