Heat resistant sewing thread, glass cloth, and method for producing glass cloth

Abstract

To provide a sewing thread scarce in thread breakage when sewing, and capable of forming a sewing part having high tensile strength even after high temperature treatment, a glass cloth sewn using the same, and a production method for the same.SOLUTION: A sewing thread includes an inorganic fiber, where the sewing thread has a weight loss when calcining for one hour at 500°C of less than 50%, and the anti-flex abrasion value expressed by the following formula: anti-flex abrasion value=flexure durable time [s] in slide testing / thickness [tex] of the sewing thread is in a range of 0.16 or more and 4.2 or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a heat-resistant sewing thread, a glass cloth, and a method for manufacturing the glass cloth. [Background technology]

[0002] Glass cloth used for flame-retardant fabrics, heat-resistant protective fabrics, etc., uses highly heat-resistant sewing threads for sewing. Organic fibers with high sewing performance generally have low heat resistance, and even aramid fibers, which have relatively high heat resistance, only have a heat resistance of around 400°C to 500°C. Therefore, inorganic fibers or metal fibers are used for applications requiring high heat resistance at temperatures exceeding that, for example, temperatures exceeding 500°C. However, inorganic fiber sewing threads have low durability, and various external forces, such as friction and tension, exerted by the needle hole and thread guide of a sewing machine during sewing can cause the surface of the sewing thread to fluff, leading to the thread easily fraying and breaking.

[0003] One known means for improving the sewing performance of inorganic fibers is to combine them with organic fibers (Patent Documents 1 to 3). More specifically, Patent Document 1 describes a yarn obtained by mixing and twisting glass fiber yarn and para-aramid fiber yarn, and also states that the glass fiber yarn can compensate for the lack of heat resistance of the para-aramid fiber, and that the para-aramid fiber yarn can compensate for the mechanical fragility due to the poor bending resistance that is unique to glass fiber. Patent Document 2 describes a yarn in which organic fibers are arranged around the glass fiber by plying and twisting, and the yarn surface is coated by immersing the yarn in a fluororesin. Furthermore, Patent Document 3 describes a twisted yarn for sewing glass cloth, in which the pitch of the mixed twisted yarn of glass fiber and chemical fiber is within a predetermined range and the yarn surface is coated with a silicone coating.

[0004] In addition to its flame retardant and heat-resistant protective applications, glass cloth is also used as an electronic material, such as an insulating material for thinner printed wiring boards. With the increasing performance of information terminals such as smartphones and the trend toward high-speed communications typified by 5G communications, there is a demand for further improvements in the dielectric properties (e.g., lower dielectric loss tangent) of glass cloth, which is used as an insulating material for printed wiring boards for high-speed communications.

[0005] As a means for improving dielectric properties, for example, a method of producing a prepreg using low dielectric glass is known (Patent Document 4 and Patent Document 5). More specifically, Patent Document 4 describes producing a prepreg using glass yarns with a silicon dioxide (SiO2) composition content of 98 mass % or more and 100 mass % or less. Patent Document 5 describes heat-treating a quartz glass cloth in order to further reduce the dielectric loss tangent.

[0006] It is known that glass cloth used for printed wiring boards is subjected to a thermal deoiling treatment to remove organic binders such as starch and PVA adhering to the glass fibers. From the viewpoint of productivity, the thermal deoiling treatment is often performed on rolled glass cloth using a batch-type heating furnace, with multiple rolls of glass cloth being treated at once. Furthermore, Patent Document 6 describes a method for improving productivity in which glass cloth is connected to itself by bonding with a thermal adhesive tape in a process of performing some kind of processing on the glass cloth using a roll-to-roll method. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2-68326 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-064836 [Patent Document 3] Japanese Utility Model Application Publication No. 62-088774 [Patent Document 4] Japanese Patent Application Publication No. 2018-127747 [Patent Document 5] International Publication No. 2022 / 215287 [Patent Document 6] Japanese Patent Application Laid-Open No. 2003-166164 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present disclosure is to provide a sewing thread that is less likely to break during sewing and that can form a sewn section that has high tensile strength even after high-temperature treatment, as well as a glass cloth sewn using the sewing thread and a method for manufacturing the same. [Means for solving the problem]

[0009] Some of the embodiments of the present disclosure are exemplified in the following items [1] to

[20] . [1] A sewing thread comprising inorganic fibers, The sewing thread loses less than 50% of its weight when fired at 500°C for 1 hour, The sewing thread has the following formula: Flexing wear resistance value = Flexing endurance time during sliding test [s] / thickness of sewing thread [tex] The bending wear resistance value, expressed as the following formula, is in the range of 0.16 or more and 4.2 or less, and the bending durability time in the sliding test is measured by the following steps (1) to (4). (1) One end of the sewing thread is fixed to one of two fixing parts with an inner dimension of 18 cm, and the other end of the sewing thread is passed through the eye of a needle with a Japanese count of #21, and then tensioned by applying a load of 1.5 x the thickness (tex) g of the sewing thread to the other fixing part; (2) The needle is pressed down and fixed with a load of 118 g so that the needle hole is positioned at the center of the two fixing parts and the height from the center of the needle hole to the fixing part of the sewing thread is 1.5 cm, and this is the initial position; (3) Starting from the initial position, the sample is slid back and forth 4 cm at a time (8 cm per stroke) in the direction in which the sewing thread is stretched, at a rate of 2 strokes per second, and the time (s) from the start of sliding until the sewing thread completely breaks is measured; (4) Steps (1) to (3) are carried out five times, and the obtained times (s) are averaged to calculate the bending endurance time (s) of the sewing thread. [2] Item 2. The sewing thread according to item 1, wherein the weight loss of the sewing thread when calcined at 500°C for 1 hour is less than 35%. [3] Item 2. The sewing thread according to item 1, wherein the sewing thread is not mixed with metal fibers. [4] Item 1. The sewing thread according to item 1, wherein the organic fibers are not intertwisted. [5] Item 2. The sewing thread according to item 1, wherein the bending durability time is 13 seconds or more. [6] Item 1. The sewing thread according to item 1, wherein the thickness of the sewing thread is 200 tex or less. [7] Item 2. The sewing thread according to item 1, wherein the surface of the sewing thread is surface-treated with a sizing agent. [8] 8. The sewing thread according to item 7, wherein the sizing agent does not contain a fluorine compound. [9] Item 2. The sewing thread according to item 1, wherein the ignition loss value of the sewing thread is 2.0% by mass or more.

[10] Item 1. The sewing thread according to item 1, wherein the number of twists of the sewing thread is in the range of 0.3 turns / 25 mm to 8.0 turns / 25 mm.

[11] Item 2. The sewing thread according to item 1, wherein the sewing thread has an average coefficient of friction (MIU value) of 0.23 or less. The MIU value is obtained by measuring the coefficient of friction when the friction element is advanced under the conditions below using a sample in which the sewing threads are arranged at intervals of 6 threads / cm along the direction of advancement of the friction element, and averaging the values ​​obtained by performing this measurement five times. Measuring device: Friction tester KES-SE (manufactured by Kato Tech Co., Ltd.) Contact material: 10mm square piano wire sensor SENS:H SPEED: 1 (1 mm / sec) Friction load: 50g Measurement distance: 30mm Temperature: 25℃ Humidity: 50%

[12] Item 2. The sewing thread according to item 1, wherein the total content of Na and Mg is 1.5% by mass or less in terms of Na2O and MgO.

[13] Item 1. The sewing thread for sewing glass cloth.

[14] Item 14. The sewing thread according to item 13, wherein the glass cloth is configured with glass yarns containing a plurality of filaments as warp and weft yarns, and the silicon (Si) content of the glass yarns is 95.0% by mass to 100% by mass in terms of silicon dioxide (SiO2).

[15] A glass cloth sewn with the sewing thread according to any one of items 1 to 12.

[16] Item 16. The glass cloth according to item 15, wherein the glass yarns are formed as warp and weft yarns, each containing a plurality of filaments, and the silicon (Si) content of the glass yarns is 95.0% by mass to 100% by mass in terms of silicon dioxide (SiO2).

[17] A method for manufacturing a glass cloth, comprising a sewing step of sewing glass cloths together with sewing thread, The sewing thread contains inorganic fibers, The sewing thread loses less than 50% of its weight when fired at 500°C for 1 hour, The sewing thread has the following formula: Flexing wear resistance value = Flexing endurance time during sliding test [s] / thickness of sewing thread [tex] The flexing wear resistance value represented by the following formula (1) is in the range of 0.16 or more and 4.2 or less, and the flexing durability time in the sliding test is measured by the following steps (1) to (4), (1) One end of the sewing thread is fixed to one of two fixing parts with an inner dimension of 18 cm, and the other end of the sewing thread is passed through the eye of a needle with a Japanese count of #21, and then tensioned by applying a load of 1.5 x the thickness (tex) g of the sewing thread to the other fixing part; (2) The needle is pressed down and fixed with a load of 118 g so that the needle hole is positioned at the center of the two fixing parts and the height from the center of the needle hole to the fixing part of the sewing thread is 1.5 cm, and this is the initial position; (3) Starting from the initial position, the sample is slid back and forth 4 cm at a time (8 cm per stroke) in the direction in which the sewing thread is stretched, at a rate of 2 strokes per second, and the time (s) from the start of sliding until the sewing thread completely breaks is measured; (4) Steps (1) to (3) are carried out five times, and the obtained times (s) are averaged to calculate the bending endurance time (s) of the sewing thread.

[18] Item 18. The method for producing a glass cloth according to Item 17, wherein the weight loss of the sewing thread when fired at 500°C for 1 hour is less than 35%.

[19] Item 18. The method for producing a glass cloth according to Item 17, wherein the sewing thread is not mixed with metal fibers.

[20] Item 18. The method for producing a glass cloth according to Item 17, wherein the sewing thread is not mixed with organic fibers. [twenty one] Item 19. A method for producing a glass cloth according to Item 17 or 18, comprising the step of subjecting the glass cloth to a heat deoiling treatment after the sewing step. [twenty two] Item 19. The method for producing a glass cloth according to Item 17 or 18, wherein the glass cloth is formed of glass yarns each containing a plurality of filaments as warp and weft, and the silicon (Si) content of the glass yarns is 95.0% by mass to 100% by mass in terms of silicon dioxide (SiO2). [twenty three] Item 22. The method for producing a glass cloth according to Item 21, wherein the thermal deoiling treatment comprises a step of thermally deoiling the glass cloth at a temperature in the range of 500°C to 1500°C. [twenty four] Item 24. The method for producing a glass cloth according to Item 21 or 23, wherein the thermal deoiling treatment comprises a step of thermally deoiling the glass cloth while transporting it. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a sewing thread that is less likely to break during sewing and that can form a sewn section that has high tensile strength even after high-temperature treatment, as well as a glass cloth sewn using the sewing thread and a method for manufacturing the same. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram of a sliding tester for measuring the bending endurance time and bending wear resistance value of sewing thread. [Figure 2] FIG. 2 is a schematic diagram for explaining a method for measuring the tensile strength of a sewn portion. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present disclosure will be described. The present disclosure is not limited to the present embodiment, and various modifications are possible without departing from the spirit thereof. In this embodiment, a numerical range described using "to" includes the numerical values ​​before and after "to" as the upper and lower limits. In this embodiment, in a numerical range described in stages, the upper or lower limit described in a certain numerical range can be replaced with the upper or lower limit of another numerical range described in stages. In this embodiment, the upper or lower limit described in a certain numerical range can also be replaced with a value shown in the examples. In this embodiment, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the function of the process is achieved.

[0013] Sewing thread The sewing thread of the present disclosure is a sewing thread containing inorganic fibers, has heat resistance of 500°C or higher, and is represented by the following formula: Flexing abrasion resistance value = Flexing endurance time during sliding test [s] / Sewing thread thickness [tex] The flex abrasion resistance value, expressed as the value obtained by controlling the heat resistance and flex abrasion resistance of the sewing thread, is in the range of 0.16 or more and 4.2 or less. The present inventors have focused on the relationship between the physical properties of the sewing thread, the frequency of thread breakage, and the tensile strength of the sewn part sewn with the sewing thread after high-temperature treatment, and have conducted extensive research to solve the problems of the present disclosure. As a result, they have focused on the heat resistance and flex abrasion resistance of the sewing thread, and have found that by using a sewing thread in which these properties are controlled, thread breakage during sewing is reduced and a sewn part having high tensile strength even after high-temperature treatment can be formed.

[0014] The sewing thread of the present disclosure is not limited to a specific application, but is preferably used for sewing glass cloth. The sewing thread of the present disclosure is particularly suitable for use in sewing glass cloth together when switching between glass cloths in the manufacture of glass cloth for printed wiring boards, which involves a process of heating the glass cloth to high temperatures using a roll-to-roll method. For example, Patent Document 5 describes high-temperature heating using a roll-to-roll method. However, with the conventional cloth switching method using thermal adhesive tape, as described in Patent Document 6, the thermal adhesive tape can burn, making it impossible to switch between glass cloths. As an alternative to the conventional method, a method of switching between glass cloths using a high-temperature resistant sewing thread is considered. For example, Patent Document 3 discloses sewing glass cloth used for flame-retardant fabrics, heat-resistant protective fabrics, etc., with highly heat-resistant inorganic and metal fibers. However, with the miniaturization of printed wiring boards, the thickness of glass cloth used as an insulating material for printed wiring boards is typically in the range of several μm to 100 μm, which is thinner than glass cloth used for flame-retardant fabrics, heat-resistant protective fabrics, etc. Therefore, in order to reduce damage to the glass cloth, sewing with thin needles is required, and it has been found that the sewing thread used for sewing is required to have higher sewing performance (i.e., less thread breakage during sewing). In this regard, the sewing thread of the present disclosure reduces thread breakage during sewing and can form sewn parts that have high tensile strength even after high-temperature treatment, and therefore can be suitably used to sew glass cloths together when manufacturing glass cloth for printed wiring boards using a roll-to-roll method that involves heating at high temperatures.

[0015] (material) The sewing thread contains inorganic fibers and has heat resistance of 500°C or higher. Here, "having heat resistance" means that the weight loss rate of the sewing thread is less than 50% when heated at a certain temperature for 1 hour. For example, an inorganic fiber that has a weight loss rate of 20% when heated at 500°C for 1 hour can be said to have heat resistance of 500°C or higher. The weight loss rate tends to increase as the measurement temperature increases. Therefore, if it is confirmed that the weight loss rate of a sewing thread is less than 50% when heated at a certain temperature (e.g., 1000°C) for 1 hour, it can also be said to have heat resistance at temperatures lower than that temperature (e.g., 800°C, 600°C, 500°C, etc.). The sewing thread preferably has heat resistance of 550°C or higher, more preferably 600°C or higher, 650°C or higher, 700°C or higher, 800°C or higher, 900°C or higher, or 1000°C or higher. The inorganic fibers are not particularly limited as long as they have heat resistance of 500°C or higher, but examples include glass fibers, alumina fibers, and basalt fibers. From the viewpoint of mechanical strength against friction and bending, glass fibers are preferred, and from the viewpoint of heat resistance, quartz glass fibers and silica glass fibers, which have a particularly high silicon dioxide (SiO2) content, are preferred. The silicon (Si) content of the sewing thread is more preferably 95.0% to 100% by mass, calculated as silicon dioxide (SiO2). Furthermore, the weight loss rate when heated at each temperature (e.g., 500°C) for 1 hour is preferably less than 35%, more preferably less than 30%, even more preferably less than 25%, and particularly preferably less than 20% or less than 15%.

[0016] The total Na and Mg content in the sewing thread, calculated as Na2O and MgO, is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, even more preferably 0.5% by mass or less, even more preferably 0.3% by mass or less, and particularly preferably 0.1% by mass or less. As described in the Examples, the Na2O and MgO contents can be determined by measuring the Na and Mg content in the glass using ICP atomic absorption spectrometry and optical emission spectrometry and converting the results to oxide values. Since Na and Mg ions cleave the siloxane bonds that make up the glass at high temperatures, keeping the Na2O and MgO content to 1.5% by mass or less helps prevent a decrease in the strength of the glass cloth sewn portion when heated to 500°C or higher. The lower limit of the total Na2O and MgO content may be 0 or greater. Furthermore, although not limited to a particular application, when the total content of NaO and MgO in the sewing thread is 1.5 mass % or less, it is possible to effectively prevent a decrease in strength of the sewn parts of the glass cloth due to heating, and therefore, when a glass cloth having sewn parts is subjected to thermal deoiling while being transported by a roll-to-roll method, thread breakage and fractures in the sewn parts are reduced.

[0017] The sewing thread preferably has a mixed twist ratio of organic fibers of less than 35%, and it is particularly preferable that the organic fibers are not mixed. When the sewing thread is a mixed twist yarn of inorganic fibers and organic fibers, it tends to have high flex abrasion resistance and is easy to prevent thread breakage during sewing. Furthermore, when the mixed twist ratio of organic fibers is less than 35%, the tensile strength of the sewn part is improved when heated at high temperatures of 500°C or higher. For example, Patent Documents 1 and 2 describe a method of improving the mechanical brittleness of inorganic fibers by combining (mixing) them with organic fibers that have excellent mechanical properties. Patent Document 3 also describes twisting glass fibers and chemical fibers at a predetermined pitch to form a silicone coating on the surface. However, when a mixed twist yarn containing a large amount of organic fibers is used, the organic fibers melt or burn off when the sewn part is heated at a high temperature, for example, 500°C, causing the thread to thin. Furthermore, the heat generated when the organic fibers burn reduces the tensile strength of the sewn part. In this regard, the sewing thread of the present disclosure preferably has a low twist ratio of organic fibers, and particularly preferably contains no organic fibers. This effectively prevents the sewing thread after heating from becoming too thin compared to the hole made in the substrate by the needle during sewing, and from being damaged by the heat of combustion of the organic fibers, and tends to increase the tensile strength of the sewn part after high-temperature heating. The twist ratio of the organic fibers in the sewing thread is preferably less than 35%, more preferably less than 30%, even more preferably less than 25%, even more preferably less than 20%, and particularly preferably less than 15% or less than 10%. It is particularly preferred that the sewing thread does not contain any twisted organic fibers. The twist ratio (%) of the organic fibers in the sewing thread can be determined by dividing the thickness T1 (tex) of the organic fibers contained in the sewing thread by the thickness T2 (tex) of the sewing thread.

[0018] The sewing thread preferably has a mixed twist ratio of metal fibers of less than 10%, and it is particularly preferable that no metal fibers are mixed in. Metal fibers have higher sewing performance than inorganic fibers. While metal fibers have sufficient mechanical strength against external forces applied during sewing, their high rigidity makes the sewn area prone to waving, and the tensile strength of the sewn area is easily reduced. In this regard, a mixed twist ratio of metal fibers of less than 10% makes it easier to increase the tensile strength of the sewn area after high-temperature heating. Furthermore, when sewing glass cloth for printed wiring boards, a mixed twist ratio of metal fibers of less than 10% makes it easier to prevent insulation defects in the printed wiring board. The mixed twist ratio of metal fibers in the sewing thread is more preferably less than 8%, even more preferably less than 5%, even more preferably less than 3%, and particularly preferably less than 1% or less than 0.5%. It is particularly preferable that no metal fibers are mixed in the sewing thread. The mixed twist ratio of metal fibers in the sewing thread (%) can be calculated by dividing the thickness T4 (tex) of the metal fibers contained in the sewing thread by the thickness T2 (tex) of the sewing thread.

[0019] (Flexural wear resistance value) The sewing thread has a flex abrasion resistance value of 0.16 to 4.2, where the flex abrasion resistance value is a value calculated from the flex endurance time during a sliding test and the thickness of the sewing thread, as shown in the following formula. Flexing abrasion resistance value = Flexing endurance time during sliding test [s] / Sewing thread thickness [tex] The bending endurance time during the sliding test is measured by passing a sewing thread through a needle, sliding the needle under load, and measuring the time until the thread breaks. More specifically, the bending endurance time is measured by the following steps (1) to (4). (1) One end of the sewing thread is fixed to one of two fixing parts with an inner dimension of 18 cm, and the other end of the sewing thread is passed through the eye of a needle with a Japanese count of #21, and then tensioned by applying a load of 1.5 x the thickness (tex) g of the sewing thread to the other fixing part; (2) Fix the needle in the initial position by applying a load of 118 g and pushing it down so that the needle hole is located in the center of the two fixing parts and the height from the center of the needle hole to the fixing part of the sewing thread is 1.5 cm; (3) Starting from the initial position, the sample is slid back and forth 4 cm at a time (8 cm per stroke) in the direction of the tension of the sewing thread at a rate of two strokes per second, and the time (s) from the start of the stroke to the complete breakage of the sewing thread is measured; (4) Repeat steps (1) to (3) five times, average the obtained times (s), and calculate the bending endurance time (s) of the sewing thread. The sewing thread has a flex abrasion resistance value calculated by the above formula of 0.16 or more and 4.2 or less. The flex abrasion resistance value is preferably 0.20 or more, more preferably 0.22 or more, and even more preferably 0.24 or more. The flex abrasion resistance value is preferably 2.1 or less, more preferably 1.4 or less, even more preferably 1.0 or less, and particularly preferably 0.75 or less.

[0020] Sewing threads with a flex abrasion resistance value of 0.16 or more are less likely to fuzz even when bent, resulting in good sewing efficiency (frequency of thread breakage). Furthermore, because the thread is less likely to fuzz, it is less likely to damage the substrate around the needle hole during sewing, and it is possible to obtain a sewn part with high tensile strength even after high-temperature treatment. Here, preferred methods for controlling the flex abrasion resistance value to satisfy a predetermined range include setting the thickness (tex), filament diameter, twist, etc. of the sewing thread within a predetermined range, applying a sizing agent to the sewing thread to protect the surface, and setting the type and amount of the sizing agent within a predetermined combination range, etc.

[0021] The sewing thread preferably has a bending durability time of 13 seconds or more in a sliding test. This makes it difficult for fuzz to occur when bent, even for thin threads. The bending durability time in a sliding test is preferably 16 seconds or more, more preferably 20 seconds or more. There is no particular upper limit to the bending durability time in a sliding test, but it is preferably, for example, less than 300 seconds, 299 seconds or less, 250 seconds or less, 200 seconds or less, 150 seconds or less, or 100 seconds or less.

[0022] The sewing thread preferably contains a plurality of filaments, and more preferably is a plurality of twisted filaments. The average filament diameter of the filaments constituting the sewing thread is preferably 2.5 μm or more and 15.0 μm or less, more preferably 3.5 μm or more and 12.0 μm or less, even more preferably 4.5 μm or more and 10.0 μm or less, and even more preferably 5.0 μm or more and 9.0 μm or less. When the filament diameter is 2.5 μm or more, the breaking strength of the filament is easily ensured, and the resulting sewing thread is less likely to produce fluff. Furthermore, when the filament diameter is 15.0 μm or less, the rigidity of the sewing thread can be prevented from becoming too high, and therefore, the flex abrasion resistance value can be easily controlled.

[0023] The twist of the sewing thread is preferably 0.3 turns / 25 mm or more and 8.0 turns / 25 mm or less, more preferably 0.6 turns / 25 mm or more and 7.0 turns / 25 mm or less, even more preferably 0.7 turns / 25 mm or more and 6.0 turns / 25 mm or less, and particularly preferably 0.8 turns / 25 mm or more and 5.0 turns / 25 mm or less. The twist direction may be either Z or S. When the twist is 0.3 turns / 25 mm or more, the convergence of the filaments is easily ensured, and the resulting sewing thread is less likely to produce fuzz. Furthermore, when the twist is 8.0 turns / 25 mm or less, the force applied to the filaments can be prevented from becoming too large, and the resulting sewing thread is less likely to produce fuzz, making it easier to control the flex abrasion resistance value.

[0024] The thickness of the sewing thread is preferably 10 tex or more and 200 tex or less, more preferably 20 tex or more and 170 tex or less, even more preferably 30 tex or more and 150 tex or less, and particularly preferably 40 tex or more and 120 tex or less. When the thickness of the sewing thread is 10 tex or more, it is easy to ensure the mechanical strength of the sewing thread, so that the resulting sewing thread is less likely to generate fuzz and the flex abrasion resistance value is easy to control. Furthermore, when the thickness of the sewing thread is 200 tex or less, it is possible to prevent the sewing thread from becoming too thick for the needle hole, so that it is less likely to generate fuzz during sewing and the flex abrasion resistance value is easy to control.

[0025] The tensile strength of the sewing thread is preferably 10 N / thread or more, more preferably 20 N / thread or more, and particularly preferably 25 N / thread or more. When the strength of the sewing thread is 10 N / thread or more, it is easy to ensure the mechanical strength of the sewing thread, so that the resulting sewing thread is less likely to generate fluff and the flex abrasion resistance value is easy to control. There is no particular upper limit to the tensile strength of the sewing thread, but it is preferably, for example, 300 N / thread or less.

[0026] (sizing agent) The sewing thread is preferably surface-treated with a sizing agent. From the viewpoints of improving the convergence of the sewing thread, reducing fuzz, controlling the flex abrasion resistance, and improving surface smoothness, the sizing agent preferably contains, as a main component, at least one selected from the group consisting of starch, PVA resin, polyurethane resin, epoxy resin, and acrylic resin. From the viewpoints of reducing fuzz and improving the flex abrasion resistance, the sizing agent more preferably contains, as a main component, starch and / or PVA resin. Here, the "main component" refers to the component that accounts for the largest mass % based on the total mass of the sizing agent. For example, the main component may be a component that accounts for 50 mass % or more, 65 mass % or more, 80 mass % or more, or 95 mass % or more of the sizing agent.

[0027] The sizing agent preferably contains silicone oil. By including silicone oil in the sizing agent, it becomes easier to control the surface smoothness within a predetermined range. However, it is preferable that the sizing agent does not contain silicone as a main component. For example, the content of silicone oil is preferably more than 0% by mass but not more than 10% by mass, more preferably 0.3% by mass or more and not more than 5% by mass, and even more preferably 0.5% by mass or more and not more than 3% by mass, based on the total mass of the sizing agent. A silicone oil content of 10% by mass or less prevents the sizing agent from transferring to the surrounding area and sliding off, while making it easier to control the surface smoothness within a predetermined range. Furthermore, the film-forming properties of the sizing agent are improved, making it easier to control the flex abrasion resistance value within a predetermined range. Furthermore, the sizing agent containing silicone burns after high-temperature heating, preventing silicon dioxide powder from remaining on the surface of the sewing thread. This reduces friction in the sewn area after high-temperature heating and increases tensile strength.

[0028] In order to prevent the generation of various harmful decomposition products containing fluorine upon combustion, it is preferable that the sizing agent does not contain fluorine compounds.

[0029] The amount of sizing agent attached to the sewing thread, i.e., the ignition loss of the sewing thread, is preferably 2.0% by mass or more, more preferably 2.0% by mass or more but less than 15.0% by mass, even more preferably 3.5% by mass or more but less than 12.0% by mass, even more preferably 5.0% by mass or more but less than 10.0% by mass, and particularly preferably 6.0% by mass or more but less than 9.0% by mass. When the ignition loss of the sewing thread is 2.0% by mass or more, it is easy to obtain a sewing thread that exhibits good flex abrasion resistance and surface smoothness. Here, the ignition loss is measured in accordance with JIS R3420.

[0030] (Surface smoothness) The average coefficient of friction (MIU value) of the sewing thread is preferably 0.23 or less. The MIU value, which relates to the surface smoothness of the sewing thread, is measured by placing a friction element on the sewing thread and measuring the force applied to the friction element as the sewing thread is moved at a predetermined speed. More specifically, the MIU value is obtained by measuring the coefficient of friction five times while moving the friction element along the direction of the friction element, using a sample in which the sewing threads are arranged at intervals of 6 threads / cm. The measurement is performed under the following conditions, and the average of the values ​​obtained is obtained. The conditions are: measuring device: friction tester KES-SE (manufactured by Kato Tech Co., Ltd.); contact member: 10 mm square piano wire sensor; SENS: H; SPEED: 1 (1 mm / sec); friction element load: 50 g; measurement distance: 30 mm; temperature: 25°C; and humidity: 50%. The upper limit of the MIU value is preferably 0.22 or less, more preferably 0.21 or less, even more preferably 0.20 or less, and particularly preferably 0.19 or less. There is no particular lower limit to the MIU value, but it is preferably 0.05 or more.

[0031] Sewing threads with an MIU value of 0.23 or less tend to cause less damage to the substrate around the sewing holes during sewing, and therefore tend to have higher tensile strength in the sewn portion after high-temperature heating. Preferred methods for controlling the MIU value to fall within a predetermined range include applying a sizing agent to the sewing thread to protect the surface and adjusting the type and amount of the sizing agent to a predetermined combination range, adding silicone oil to the sizing agent, or applying the sizing agent by spraying.

[0032] Glass cloth sewn products The present disclosure also provides glass cloth sewn with the sewing thread of the present disclosure (hereinafter also referred to as "glass cloth sewn product"). The glass cloth sewn product has excellent heat resistance and has sewn parts that maintain high tensile strength even after high-temperature treatment. The glass cloth sewn product has the sewing thread of the present disclosure and glass cloth as a substrate. The substrate is preferably a substrate that has high heat resistance, for example, heat resistance of 500°C or higher. By being sewn with the sewing thread of the present disclosure, the glass cloth sewn product can have sewn parts that maintain excellent heat resistance and high tensile strength even after high-temperature heating. Furthermore, the glass cloth sewn product has sewn parts with good sewing quality due to reduced thread breakage, and this effect is particularly noticeable when the substrate is thin glass cloth for electronic materials.

[0033] The glass cloth has a woven structure using glass yarns containing a plurality of glass filaments as warp and weft. Examples of the weave structure of the glass cloth include plain weave, sash weave, satin weave, and twill weave. Among these, the plain weave structure is preferred.

[0034] The pitch density of the warp and weft yarns constituting the glass cloth is preferably 10 to 120 yarns / inch (=10 to 120 yarns / 25 mm), more preferably 40 to 100 yarns / inch. If the pitch density is within the above range, a glass cloth of a preferred thickness is easily obtained. The pitch densities of the warp and weft yarns may be different.

[0035] The weight of the glass cloth (mass of the glass cloth) is preferably 8 to 250 g / m 2 , more preferably 8 to 100 g / m 2 , more preferably 8 to 80 g / m 2 , particularly preferably 8 to 50 g / m 2 The weight of the glass cloth is 8 to 250 g / m 2 If so, a glass cloth having a desirable thickness can be easily obtained.

[0036] The thickness of the glass cloth is preferably 110 μm or less, more preferably 100 μm or less, even more preferably 60 μm or less, and particularly preferably 50 μm or less. If the thickness of the glass cloth is 110 μm or less, it is easy to obtain a glass cloth suitable as an insulating material. The thickness of the glass cloth may be more than 0 μm, 5 μm or more, or 10 μm or more.

[0037] The composition of the glass yarns constituting the glass cloth is not particularly limited, but may be E-glass (alkali-free glass), which is commonly used for electronic materials, or other types such as L-glass, NE-glass, D-glass, L2-glass, S-glass, T-glass, silica glass, and quartz glass. As with the sewing thread, the glass cloth used for sewing preferably has a low Na2O and MgO content in order to prevent a decrease in strength of the sewn portion. Specifically, glass cloth made using silica glass yarns or quartz glass yarns is preferred, and glass cloth having a silicon (Si) content of 95.0% to 100% by mass, calculated as silicon dioxide (SiO2), is more preferred.

[0038] The average filament diameter of the glass filaments constituting the glass yarn used in the glass cloth is preferably 2.5 μm to 9.0 μm, more preferably 2.5 μm to 7.5 μm, even more preferably 3.5 μm to 7.0 μm, still more preferably 3.5 μm to 6.0 μm, and particularly preferably 3.5 μm to 5.0 μm. When the filament diameter is 2.5 μm or more, the breaking strength of the filaments is easily ensured, and the resulting glass cloth is less likely to produce fluff. Furthermore, when the filament diameter is 9.0 μm or less, the mass of the glass cloth can be prevented from becoming too large, making it easy to transport or process.

[0039] <<Sewing thread manufacturing method>> The sewing thread is obtained by applying a sizing agent to a thread containing inorganic fibers made of a material having a heat resistance of, for example, 500° C. or higher. The method for producing the sewing thread may optionally further include a step of twisting the thread.

[0040] <Yarn twisting process> The twisting method is not particularly limited as long as it can twist a yarn containing inorganic fibers to a predetermined thickness and twist number, and any conventional known technique can be used. The preferred materials and configurations of the yarns to be used are as described above.

[0041] <Sizing agent application process> The method for applying the sizing agent to the sewing thread is not particularly limited, and conventional publicly known techniques can be used. The application method may be performed before, during, or after the twisting step. For example, the sizing agent application step may include a coating step in which a treatment liquid containing a sizing agent at a concentration of 5.0% to 20% by mass is applied to the surface of the inorganic fiber-containing thread. The sizing agent application step may further include a fixing step in which the sizing agent is fixed to the surface of the inorganic fiber-containing thread by heat drying. This makes it easier to coat the inorganic fiber thread with the sizing agent.

[0042] Methods for applying the treatment liquid to the inorganic fiber yarn in the coating process include (a) a method in which the inorganic fiber yarn is immersed in or passed through a treatment liquid stored in a bath (hereinafter referred to as the "immersion method"), (b) a method in which the treatment liquid is applied to the inorganic fiber yarn using a roll coater, die coater, gravure coater, or the like, and (c) a method in which the treatment liquid is applied to the inorganic fiber yarn by spraying (hereinafter referred to as the "spray method"), etc.

[0043] When the immersion method is employed, the immersion time of the inorganic fiber yarn in the treatment solution is preferably set to 0.5 seconds or more and 1 minute or less. Furthermore, when the immersion method is employed, the inorganic fiber yarn can be conveyed under tension and passed through the treatment solution. Furthermore, after the treatment solution is applied to the inorganic fiber yarn, the solvent contained in the treatment solution can be heated and dried using methods such as hot air or electromagnetic waves. To facilitate uniform application of the sizing agent to the inorganic fiber yarn surface, it is preferable to immerse the inorganic fiber yarn in the treatment solution and then squeeze it at a constant pressure using a rubber roller. After the treatment solution is applied to the inorganic fiber yarn, a fixing step may be further performed in which the solvent contained in the treatment solution is heated and dried using methods such as hot air or electromagnetic waves.

[0044] When the spray method is employed, the inorganic fiber yarns can be transported and passed through an atmosphere in which the treatment liquid has been sprayed (hereinafter also referred to as the "treatment liquid atmosphere"). The exposure time of the inorganic fiber yarns to the treatment liquid atmosphere is preferably set to 0.5 seconds or more and 1 minute or less. After the treatment liquid is applied to the inorganic fiber yarns, a fixing step may be further carried out in which the solvent contained in the treatment liquid is heated and dried using a method such as hot air or electromagnetic waves. The spray method makes it difficult for excess treatment liquid to adhere, and does not require a step of removing the excess treatment liquid, for example, by squeezing it, thereby eliminating the anisotropy of the inorganic fiber yarns and making it easier to apply the sizing agent more uniformly to the surface of the inorganic fiber yarns. The discharge rate of the treatment liquid in the treatment liquid atmosphere is preferably 1 to 50 g / min, more preferably 5 to 20 g / min, from the viewpoint of making it easier to apply the sizing agent more uniformly to the surface of the inorganic fiber yarns.

[0045] The concentration of the sizing agent in the treatment liquid is preferably 5.0% by mass to 20% by mass, more preferably 7.0% by mass to 18% by mass, and even more preferably 10% by mass to 15% by mass, based on the total mass of the treatment liquid, which makes it easier to perform a more suitable surface treatment on the inorganic fiber yarn.

[0046] In the fixing step, the heat drying temperature is not particularly limited as long as it is a temperature at which the solvent can be removed, but is preferably 80° C. or higher, more preferably 90° C. or higher. In addition, the heat drying temperature is preferably 300° C. or lower, more preferably 180° C. or lower, in order to prevent deterioration of the sizing agent.

[0047] The above steps do not necessarily have to be performed in a manner that can be distinguished as separate steps, and multiple steps can be performed together (simultaneously). Furthermore, the method for manufacturing sewing threads can include any steps other than the above steps. Furthermore, the order of the above steps can be changed if possible.

[0048] <<Method for manufacturing sewn glass cloth products>> The method for manufacturing a glass cloth sewn product of the present disclosure includes a step of sewing glass cloth using the sewing thread of the present disclosure. The sewing thread and the glass cloth sewn product are as described above in the "Sewing thread" and "Glass cloth sewn product" sections.

[0049] <Sewing process> The sewing method is not particularly limited, but examples include mechanical sewing using a sewing machine, from the viewpoint of shortening the sewing time and ensuring uniform sewing quality. The sewing machine used may be either a lockstitch machine or a chainstitch machine, and the number of needles is not particularly limited. From the viewpoint of reducing damage to the sewing thread, it is preferable to use a lockstitch machine. Furthermore, from the viewpoint of reducing damage to the base material, the needle used is preferably #24 or smaller in Japanese count, more preferably #21 or smaller, even more preferably #19 or smaller, and particularly preferably #14 or smaller. From the viewpoint of reducing damage to the glass cloth, a patch cloth can also be used in the sewn area.

[0050] <Thermal deoiling process> The method for producing a sewn product according to the present disclosure preferably includes a step of subjecting the glass cloth to a thermal deoiling treatment after the sewing step. The thermal deoiling treatment is more preferably carried out while the glass cloth is being transported, for example, by a roll-to-roll method. This makes it easier to reduce the amount of sizing agent in the glass cloth. By using the sewing thread according to the present disclosure, it is possible to easily switch cloths during a thermal deoiling treatment at high temperatures (for example, 500°C or higher) using a roll-to-roll method.

[0051] The temperature for thermal deoiling is preferably 500°C or higher and 1500°C or lower, more preferably 800°C or higher and 1300°C or lower, and even more preferably 900°C or higher and 1100°C or lower. If the thermal deoiling temperature is 500°C or higher, residues of sizing agent adhering to the glass cloth after thermal deoiling can be sufficiently removed. On the other hand, if the thermal deoiling temperature is 1500°C or lower, it becomes easier to suppress the devitrification phenomenon of the glass, and it becomes possible to effectively prevent a decrease in the strength of the glass cloth.

[0052] The heating time can be selected appropriately, and is preferably 1 second or more and 10 minutes or less. The upper limit of the heating time is more preferably 5 minutes or less, even more preferably 2 minutes or less, and particularly preferably 90 seconds or less. Since the heat treatment is performed at a high temperature, a heating time of 10 minutes or less reduces damage to the glass cloth, and problems such as partial holes being formed in the glass cloth or the glass cloth being cut during processing are less likely to occur. The lower limit of the heating time that can be combined with these upper limits may be more preferably 5 seconds or more, 10 seconds or more, or 15 seconds or more, from the viewpoint of effectively removing adhesive residues and the like.

[0053] The glass cloth can be heated using known heating methods, heating media, heating mechanisms, heating devices, and heating components. Examples of heating methods include (1) heating the glass cloth in a heating furnace, (2) bringing the glass cloth into contact with a heating section, and (3) applying high-temperature steam to the glass cloth. By heating the glass cloth so that the thermal deoiling temperature reaches 500°C or higher, organic matter adhering to the glass cloth surface can be efficiently removed and the time required for removing the organic matter can be shortened. The glass cloth can be heated sequentially or continuously in a closed or open system, or in a combination of a closed and an open system.

[0054] In the case of a closed system, it is preferable to place the glass cloth in a heating furnace from the viewpoint of suitable heating by a heating means, and / or it is preferable to heat the glass cloth while storing it in a rolled state from the viewpoint of storage space and heating range. Also, it is preferable to heat the glass cloth while conveying it in the heating furnace from the viewpoint of increasing the efficiency of removing organic substances and shortening the time required for removing organic substances.

[0055] In the case of an open system, it is preferable to heat the glass cloth while transporting it, from the viewpoint of the heated area. The glass cloth can be transported, for example, by an unwinding mechanism and a winding mechanism, for example, a roll-to-roll system.

[0056] (heating furnace) The heating means for the heating furnace may be an electric heater, a burner, or any other suitable means, and is not limited to a specific means. Although a combination of multiple means may be used for heating, it is preferable to use a gas single radiant tube burner or an electric heater.

[0057] From the viewpoint of heating efficiency, the heating furnace is preferably equipped with a means for discharging gas generated in the heating furnace and / or an air circulation means. The gas discharge means may be, for example, a nozzle, a gas pipe, a small hole, a gas vent valve, etc. The air circulation means may be, for example, a fan, an air conditioning system, etc.

[0058] In order to efficiently remove organic substances adhering to the surface of the glass cloth, a continuous method is preferred in which the glass cloth can be heated by passing it continuously through a heating furnace, rather than a batch method in which a glass fiber fabric is wound around a core and the glass cloth is heated at a predetermined atmospheric temperature. Furthermore, a method in which the glass cloth can be continuously washed before thermal deoiling is particularly preferred.

[0059] (Contact member for heating glass cloth) The glass cloth may be heated using the above-mentioned heating furnace, but from the viewpoint of low running costs, the glass cloth may be heated by bringing a member heated to a predetermined temperature into contact with the glass cloth.

[0060] The shape of the contact member is not particularly limited, but a roll shape is preferred because it allows for easy transport of the glass cloth. As a member capable of heating the glass cloth in a roll shape, a roll that heats by an induction heating method is preferred, as it can be used in a high-temperature range and has relatively little temperature variation in the width direction. When the glass cloth is heated by the contact member, it is considered that the temperature of the contact member and the surface temperature of the glass cloth are approximately the same.

[0061] In order to remove carbonized matter adhering to the heating roll as the glass cloth is continuously heated, the heating roll method is preferably a method equipped with a mechanism for removing adhering foreign matter, such as a mechanism such as a blade.

[0062] (Means for applying high-temperature steam to the glass cloth (steam application means)) The steam applied to the glass cloth may contain, for example, a volatile solvent, water vapor, or a gas other than water vapor. However, water vapor is preferred from the viewpoints of toxicity to the human body and the tendency to promote decomposition of the sizing agent used in the glass fiber. Regarding the temperature of the high-temperature steam, a method capable of supplying high-temperature steam and heated air at any ratio may be used, if necessary, to adjust the surface temperature of the glass cloth to, for example, a range of 500°C to 1500°C. The temperature of the high-temperature steam is 500°C or higher, preferably 600°C or higher, more preferably 700°C or higher, even more preferably 800°C or higher, and particularly preferably 900°C or higher. The means for applying the steam are not limited, and may include spraying, shower diffusion, and jet nozzles. Alternatively, gas discharged from a heating furnace may be reused as high-temperature steam.

[0063] (Glass cloth heating deoiling equipment) As described above, the thermal deoiling device for glass cloth is preferably capable of heating the glass cloth so that the thermal deoiling temperature is in the range of 500° C. to 1500° C. More specifically, the thermal deoiling device for glass cloth preferably includes a heating furnace having an unwinding mechanism and a winding mechanism, and capable of carrying out a step of heating the glass cloth so that the thermal deoiling temperature is in the range of 500° C. to 1500° C. while transporting the glass cloth.

[0064] The unwinding mechanism and the winding mechanism may be, for example, at least one pair of rolls, a roll-to-roll system, etc. The heating furnace, the air circulating means, the contact member, and the steam applying means are as described in the above-mentioned glass cloth heat treatment process. [Example]

[0065] Examples and comparative examples of the present disclosure will be described below, but the present disclosure is not limited to the following examples and comparative examples.

[0066] <<Measurement and Evaluation Methods>> <Evaluation of heat resistance of sewing thread> The sewing thread was weighed so that it was 3 g or more, and the weight W1 was measured. After that, the weight W2 after heating at a predetermined temperature in an atmospheric atmosphere for 1 hour was measured, and the weight W2 was calculated using the following formula: Weight reduction rate (%)=(W1-W2) / W1×100 The heat resistance of the sewing thread was evaluated by determining the weight loss rate using the following method. The thread was heated to 1000°C, 800°C, 600°C, and 500°C in that order, and the heat resistance was evaluated using the following index. A: Weight loss is less than 50% when fired at 1000°C for 1 hour B: Weight loss is less than 50% when fired at 800°C for 1 hour, and 50% or more when fired at 1000°C for 1 hour C: Weight loss is less than 50% when fired at 600°C for 1 hour, and 50% or more when fired at 800°C for 1 hour D: Weight loss is less than 50% when fired at 500°C for 1 hour, and 50% or more when fired at 600°C for 1 hour E: Weight loss of 50% or more when fired at 500°C for 1 hour The heat resistance evaluation results obtained are shown in the table below, with weight loss rates when fired for 1 hour at 1000°C for A, 800°C for B, 600°C for C, and 500°C for D and E. For example, if the weight loss rate at the higher temperature of 1000°C is 30%, then the weight loss rate at a lower temperature, such as 500°C, can be considered to be 30% or less. Furthermore, if the weight loss rate at the lower temperature of 500°C is 60%, then the weight loss rate at a higher temperature, such as 1000°C, can be considered to be 60% or more.

[0067] <Method for measuring the average filament diameter of sewing thread> The cross sections of 30 yarn bundles at random positions in the sewing yarn were observed under a scanning electron microscope, and the diameters of each filament were measured. The average value was calculated to determine the average filament diameter.

[0068] <Methods for measuring sewing thread thickness, tensile strength, ignition loss, and number of twists> Measurements were carried out in accordance with JIS R3420, and the thickness (= tex (g / 1000m)), tensile strength (N), ignition loss (%), and number of twists (turns / 25mm) of the sewing thread were obtained. Although JIS R3420 is a standard for continuous glass fibers, the same measurements were also applied to sewing thread.

[0069] <Organic fiber twist ratio in sewing thread> The mixed twist ratio (%) of the organic fiber in the sewing thread was calculated by dividing the thickness T1 (tex) of the organic fiber contained in the sewing thread by the thickness T2 (tex) of the sewing thread. The thickness T1 (tex) of the organic fibers in the sewing thread was calculated using the thickness T3 (tex) after the sewing thread was heated at 800°C for 1 hour in an air atmosphere after being washed with 60°C hot water and acetone to remove the sizing agent from the surface, using the following formula: T1 = T2 - T3

[0070] <Method for measuring the Na2O and MgO content of sewing thread> The sewing thread was weighed, thermally decomposed with sulfuric acid, nitric acid, and hydrofluoric acid, and then dissolved in dilute nitric acid to a constant volume. Using this solution, Na was measured by atomic absorption spectrometry and Mg was measured by ICP atomic emission spectrometry to determine the content in the sample, which was then converted into oxide values ​​to determine the Na2O and MgO contents of the sewing thread. Equipment: Raw fiber absorption spectrophotometer Hitachi High-Tech Science ZA3300 ICP optical emission spectrometer: Hitachi High-Tech Science PS3520VDDII

[0071] <Method for measuring the bending endurance time and bending abrasion resistance value of sewing thread> Figure 1 is a schematic diagram of a sliding tester 10 used to measure the flex endurance time and flex abrasion resistance value of sewing thread. The sliding tester 10 was equipped with two pins with fixed portions 12 for tensioning sewing thread 11 and a contact member 13 at the center of the pins that can slide in the thread direction, and was used to evaluate the flex endurance time and flex abrasion resistance value of the sewing thread. The test section length 14 (the inner dimension of the fixed portion 12) was 18 cm, the contact member 13 was the pinhole of an Organ Needle DP-17#21 (manufactured by Organ Needle Co., Ltd.), the contact section load 15 was 118 g, and the contact member height 16 (the height from the center of the pinhole of the contact member 13 to the fixed portion 12 of the sewing thread) was 1.5 cm.

[0072] One end of the sewing thread 11 was fixed to one of the fixed parts 12 and passed through the eye of the DP-17#21 organ needle, which served as the contact member 13. The other end of the sewing thread was then wound around the other fixed part 12, and a load 17 of 1.5 × sewing thread thickness (tex) g was applied to tension the sewing thread. The contact member 13 was then slid back and forth 4 cm at a time around the initial position in the direction of tension of the sewing thread, i.e., two strokes per second, so that the length of one stroke (sliding part length 18) was 8 cm. The time (s) from the start of sliding to complete breakage of the thread was measured. Five tests were conducted, and the average of the resulting times (s) was used to determine the flexural durability time (s) of the sewing thread. If the thread did not break after 300 seconds or more, the sliding time was evaluated as "300 seconds or more." The flexural durability time (s) was then divided by the thickness (tex) of the sewing thread to determine the flexural abrasion resistance value (s / tex).

[0073] <Method for measuring the MIU value of sewing thread> The MIU value of the sewing thread was measured using a friction tester KES-SE manufactured by Kato Tech Co., Ltd. Using a sample in which the sewing threads were arranged at intervals of 6 threads / cm along the direction of the friction probe, the MIU value was measured when the friction probe was moved under the following conditions. This operation was carried out five times, and the obtained values ​​were averaged to obtain the MIU value of the sewing thread. (Test conditions) Contact material: 10mm square piano wire sensor SENS:H SPEED: 1 (1 mm / sec) Friction load: 50g ·Measurement distance: 30mm ·Temperature: 25℃ ·Humidity: 50%

[0074] <Method for evaluating frequency of yarn breakage> The sewing threads obtained in the examples and comparative examples were set as upper and lower threads in an electronic sewing machine NEXIO BAS-370H manufactured by Brother Industries, Ltd., and 70 cm of sewing (lock stitch) was performed 10 times under the following sewing conditions to evaluate the frequency of thread breakage. (Sewing conditions) Needle: DP-17#19 (Organ Needle Co., Ltd.) Upper thread tension setting value: 50 Pitch: 4mm Rotation speed: 400 rpm Base material: Q1035 2-ply

[0075] <Method for measuring tensile strength of sewn parts> FIG. 2 is a schematic diagram illustrating a method for measuring the tensile strength of a sewn portion. The sewing threads obtained in the examples and comparative examples were used as the upper and lower threads in a Brother Industries, Ltd. electronic sewing machine NEXIO BAS-370H. Sewing was performed under the same sewing conditions as in the "Method for Evaluating Thread Breakage Frequency" to obtain a glass cloth sewn product. Specifically, two Q1035 substrates (referred to as substrate A (21) and substrate B (22)) were overlapped, and one Q2116 patch cloth (23) was placed on each side of the overlap. Five 70 cm long stitches (24) were performed with a 1.5 cm spacing between the seams to obtain a glass cloth sewn product. The resulting glass cloth sewn product was then heated at 1000°C for 1 minute. Excess portions of the substrate and patch cloth were then removed, and a tensile test piece 20 was prepared with the seams perpendicular to the tensile direction and centered. To prevent thread loss, the sewn area was made 2 cm wider on both sides of the 35 mm test width. Substrate A and substrate B were then chucked in two chucking sections 30 of the autograph, 15 cm apart, and the tensile strength was measured at 200 mm / min. Three measurements were taken, and the tensile strength (N / 25 mm) was calculated from the average value.

[0076] <<Preparation of sizing agent>> [Sizing agent A: starch + PVA type] The treatment solution for sizing agent A was prepared according to the following procedure. 500 g of high-amylose etherified corn starch and 500 g of normal esterified low-viscosity corn starch were weighed and dispersed in 6 kg of water. The mixture was heated and gelatinized at 95°C for 30 minutes, and then cooled to 65°C to obtain solution A. Separately, an aqueous solution with a concentration of 10% by mass of PVA (trade name: PVA403, manufactured by Kuraray Co., Ltd.) was prepared, and 2% by weight of hydrogenated castor oil was blended with this aqueous solution as a lubricant to obtain 7 kg of solution B. Solution B was added to solution A at 65°C, and then hot water was added to make the total weight 15 kg, obtaining a treatment solution for sizing agent A.

[0077] [Sizing agent B: Sizing agent A + silicone oil] In the procedure for preparing the treatment liquid for sizing agent A, silicone oil (NP2609, manufactured by Wacker Asahi Kasei Silicone Co., Ltd.) was blended in place of hydrogenated castor oil, to obtain a treatment liquid for sizing agent B.

[0078] [Sizing agent C: Silane coupling agent] 1% by mass of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow Toray Industries, Inc.) and 3% by mass of 5-hexenyltrimethoxysilane (silane coupling agent B); Z6161 (manufactured by Dow Toray Industries, Inc.) were dispersed in pure water adjusted to pH 3 with acetic acid to obtain a treatment solution for sizing agent C.

[0079] [Sizing agent D: Fluorine resin] A 60 mass % aqueous solution of PTFE resin (AD911E, manufactured by AGC Corporation) was used as the treatment liquid for sizing agent D.

[0080] [Sizing agent E: Silicone resin] A 30% by mass aqueous solution of silicone resin (PRX308, manufactured by Dow Toray Co., Ltd.) was used as the treatment liquid for sizing agent E.

[0081] <Glass cloth manufacturing> <Production of Q1035 (gray cloth)> Glass yarns with an SiO2 content greater than 99.9% by mass were used to weave a cloth with a weave density of 66 warp yarns / 25 mm and 68 weft yarns / 25 mm using an air jet loom. The cloth width was 1300 mm. Silica glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used as the warp yarns. Silica glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used as the weft yarns. The silica glass yarns contained 0.0001% by mass of MgO and 0.0007% by mass of Na2O.

[0082] <Production of Q2116 (gray cloth)> Glass yarns with an SiO2 content greater than 99.9% by mass were used to weave a cloth with a weave density of 60 warp yarns / 25 mm and 58 weft yarns / 25 mm using an air jet loom. The cloth width was 1,300 mm. Silica glass yarns with an average filament diameter of 7.0 μm, 200 filaments, and 1.0Z twist were used as the warp yarns. Silica glass yarns with an average filament diameter of 7.0 μm, 200 filaments, and 1.0Z twist were used as the weft yarns. The silica glass yarns contained 0.0001% by mass of MgO and 0.0007% by mass of Na2O.

[0083] Examples and Comparative Examples Example 1 Silica glass yarns with an average filament diameter of 5.3 μm and an SiO2 content of more than 99.9% by mass were twisted to obtain a yarn with a thickness of 90 tex and a twist of 4.0 Z (twisting process). The MgO content of this silica glass yarn was 0.0001% by mass and the Na2O content was 0.001% by mass. Next, sizing agent A was applied to the yarn surface by a spray method. Specifically, the yarn was transported and exposed for 1.5 seconds to an atmosphere in which a treatment solution of sizing agent A was sprayed at a rate of 15 g / min from a φ0.5 nozzle (manufactured by Atmax Corporation) (coating process). Subsequently, the yarn was dried with hot air at 120°C for 20 seconds (fixing process), and then wound up to obtain a sewing yarn.

[0084] Example 2 A sewing thread was obtained in the same manner as in Example 1, except that the sizing agent was changed to sizing agent B.

[0085] Example 3 Sewing thread was obtained in the same manner as in Example 2, except that the discharge rate was increased by 1.3 times (19.5 g / min).

[0086] Example 4 Sewing thread was obtained in the same manner as in Example 2, except that the discharge rate was changed to 0.7 times (10.5 g / min).

[0087] Example 5 Silica glass yarns with an average filament diameter of 7.5 μm and an SiO2 composition content of more than 99.9% by mass were twisted to obtain yarns with a thickness of 60 tex and a twist of 1.0 S (twisting process). The silica glass yarns contained 0.0001% by mass of MgO and 0.001% by mass of Na2O. Then, sewing yarns were obtained by the same processing as in Example 2.

[0088] Example 6 Silica glass yarns with an average filament diameter of 5.3 μm and an SiO2 composition content of more than 99.9 mass% were twisted to obtain yarns with a thickness of 170 tex and a twist of 4.0 Z (twisting process). The silica glass yarns contained 0.0001 mass% MgO and 0.001 mass% Na2O. Then, sewing yarns were obtained by the same processing as in Example 2.

[0089] Example 7 After twisting the yarn in the same manner as in Example 1, sizing agent A was applied to the yarn surface by a dipping method. Specifically, the yarn was transported, dipped in a treatment solution of sizing agent A, and squeezed with an NBR rubber roll (coating step). Subsequently, the yarn was dried with hot air at 120°C for 20 seconds (fixing step), and then wound up to obtain a sewing yarn.

[0090] Example 8 Sewing thread was obtained in the same manner as in Example 7, except that the treatment liquid of sizing agent A was diluted with water to two-thirds its concentration and used.

[0091] Example 9 Alumina yarn with an average filament diameter of 7.0 μm was twisted to obtain a yarn with a thickness of 130 tex and a twist of 2.0 Z (twisting process). The MgO content of this alumina yarn was 0.003 mass% and the Na2O content was 0.004 mass%. Next, sizing agent B was applied to the yarn surface by a spray method. Specifically, the yarn was transported and exposed for 1.5 seconds to an atmosphere in which a treatment solution of sizing agent B was sprayed at a discharge rate of 15 g / min from a nozzle with a diameter of φ0.5 (manufactured by Atmax Corporation) (coating process). Subsequently, the yarn was dried with hot air at 120°C for 20 seconds (fixing process), and then wound up to obtain a sewing yarn.

[0092] Comparative Example 1 A sewing thread was obtained in the same manner as in Example 7, except that sizing agent C was used.

[0093] Comparative Example 2 Silica glass yarns with an average filament diameter of 5.3 μm and an SiO2 composition content of more than 99.9% by mass were twisted to obtain yarns with a thickness of 140 tex and a twist of 4.0 Z (twisting process). The silica glass yarns contained 0.0001% by mass of MgO and 0.001% by mass of Na2O. The remaining steps were the same as in Example 7, except that sizing agent D was used, to obtain sewing yarns.

[0094] Comparative Example 3 Sewing thread was obtained in the same manner as in Example 7, except that the treatment liquid of sizing agent A was diluted three times and used.

[0095] Comparative Example 4 E-glass yarn (alkali-free glass yarn) with an average filament diameter of 7.5 μm, containing 53% by mass of SiO, 15% by mass of AlO, and 21% by mass of CaO, was twisted to obtain a yarn with a thickness of 90 tex and a twist of 10S (twisting step). The E-glass yarn contained 2.0% by mass of MgO and 0.2% by mass of NaO. The remaining steps were similar to those in Example 7 to obtain a sewing yarn, except that sizing agent E was used.

[0096] Comparative Example 5 The SiO2 composition amount was more than 99.9 mass%, the MgO content was 0.0001 mass%, the Na2O content was 0.001 mass%, and the silica glass yarn with an average filament diameter of 5.3 μm was 30 tex, and the para-aramid fiber yarn with an average filament diameter of 12 μm was 60 tex, and twisted to obtain a yarn with a thickness of 90 tex and a twist of 10S (twisting step). Thereafter, a sewing yarn was obtained by the same processing as in Comparative Example 4.

[0097] The evaluation results for the Examples and Comparative Examples are shown in the table below.

[0098] [Table 1]

[0099] [Table 2]

[0100] <Roll-to-Roll Cross-Switching Test> A roll-to-roll cross-switching test was conducted using the sewing threads obtained in the Examples, Comparative Examples 4, and 5. The sewing threads obtained in the Examples and Comparative Examples were set as the needle and bobbin threads in a Brother Industries, Ltd. electronic sewing machine NEXIO BAS-370H, and sewing was performed under the same sewing conditions as in the "Method for Evaluating Thread Breakage Frequency." Two 530 mm wide rolls of Q1035 substrate (referred to as Substrate A and Substrate B, respectively) were overlapped with one sheet of Q2116 on each side as a patch fabric, and five stitches were then performed with a 1.5 cm gap between stitches. Using these rolls with a sewing section, the cloth was heated to 1000°C in a roll-to-roll heating furnace for one minute while being transported at a tension of 50 N. When sewing was performed using the threads of the Examples, the cloth could be transported without breakage, whereas when using the threads of the Comparative Examples, breakage occurred at the sewing section.

[0101] In Example 1, sewing was possible without thread breakage, whereas in Comparative Examples 1 and 3, thread breakage occurred frequently, making it impossible to obtain sewn products. Furthermore, in Comparative Examples 2, 4, and 5, although sewn products could be obtained despite thread breakage, toxic gases were generated by combustion at high temperatures, or it was difficult to obtain sewn products with sufficient tensile strength after high-temperature heating. The sewing thread of Example 2, which had good surface smoothness in addition to a high flex abrasion resistance, made it possible to obtain sewn products with even better tensile strength after high-temperature heating than Example 1. [Explanation of symbols]

[0102] 10. Sliding test machine 11 Sewing thread 12 Fixed part 13 Contact member 14 Test section length 15 Contact load 16 Contact member height 17 Load 18 Sliding part length 19 Sliding speed 20 tensile test specimens 21 Base material A 22 Base material B 23 Patch 24 Sewing 30 Chucking part

Claims

1. A sewing thread comprising inorganic fibers, The sewing thread has a weight loss of less than 50% when baked at 500°C for 1 hour, The sewing thread has the following formula: Flexing abrasion resistance value = flexing durability time during sliding test [s] / thickness of sewing thread [tex] The sewing thread has a flex abrasion resistance value represented by the following formula (1) to (4) in the range of 0.16 to 4.2, and the flex endurance time during the sliding test is measured by the following steps (1) to (4). (1) One end of the sewing thread is fixed to one of two fixing parts having an inner dimension of 18 cm, and the other end of the sewing thread is passed through the eye of a needle of Japanese count #21, and then a load of 1.5 x the thickness (tex) g of the sewing thread is applied to the other fixing part to tension it; (2) The needle is fixed in its initial position by applying a load of 118 g so that the needle hole is positioned at the center of the two fixing parts and the height from the center of the needle hole to the fixing parts of the sewing thread is 1.5 cm; (3) The sewing thread is slid back and forth over a distance of 4 cm (8 cm per reciprocation) in the direction in which the sewing thread is stretched, with the initial position as the center, at a sliding speed of 2 reciprocations per second, and the time (s) from the start of sliding to the complete breakage of the sewing thread is measured; (4) Steps (1) to (3) are carried out five times, and the obtained times (s) are averaged to calculate the bending endurance time (s) of the sewing thread.

2. 2. The sewing thread of claim 1, wherein the weight loss of the sewing thread is less than 35% when the sewing thread is calcined at 500°C for 1 hour.

3. The sewing thread according to claim 1 , wherein the sewing thread is not intertwined with metal fibers.

4. 10. The sewing thread of claim 1, wherein the organic fibers are not intertwisted.

5. The sewing thread according to claim 1 , wherein the bending durability time is 13 seconds or more.

6. The sewing thread according to claim 1, wherein the thickness of the sewing thread is 200 tex or less.

7. The sewing thread of claim 1 , wherein the surface of the sewing thread is surface-treated with a sizing agent.

8. The sewing thread of claim 7 , wherein the sizing agent does not contain a fluorine compound.

9. The sewing thread according to claim 1 , wherein the sewing thread has an ignition loss value of 2.0% by mass or more.

10. The sewing thread according to claim 1, wherein the number of twists of the sewing thread is in the range of 0.3 turns / 25 mm to 8.0 turns / 25 mm.

11. 2. The sewing thread of claim 1, wherein the sewing thread has an average coefficient of friction (MIU value) of 0.23 or less. The MIU value is obtained by measuring the coefficient of friction when the friction element is advanced under the following conditions using a sample in which the sewing threads are arranged at intervals of 6 threads / cm along the direction of advancement of the friction element, performing this measurement five times, and averaging the obtained values. Measuring device: Friction tester KES-SE (manufactured by Kato Tech Co., Ltd.) Contact member: 10mm square piano wire sensor SENS:H SPEED: 1 (1mm / sec) Friction load: 50g Measurement distance: 30mm Temperature: 25℃ Humidity: 50%

12. The sum of the contents of Na and Mg is Na ２ The sewing thread according to claim 1, wherein the content is 1.5% by mass or less in terms of O and MgO.

13. The sewing thread according to claim 1, which is used for sewing glass cloth.

14. The glass cloth is composed of glass yarns containing a plurality of filaments as warp and weft yarns, and the silicon (Si) content of the glass yarns is silicon dioxide (SiO ２ The sewing thread according to claim 13, wherein the total mass of the sewing thread is 95.0% by mass to 100% by mass in terms of the total mass of the polyolefins.

15. A glass cloth sewn with the sewing thread according to any one of claims 1 to 12.

16. The glass yarns containing a plurality of filaments are used as warp and weft yarns, and the silicon (Si) content of the glass yarns is silicon dioxide (SiO ２ The glass cloth according to claim 15, wherein the total mass of the glass fiber is 95.0 mass % to 100 mass % in terms of the total mass of the glass fiber.

17. A method for manufacturing a glass cloth, comprising a sewing step of sewing glass cloths together with sewing thread, The sewing thread comprises inorganic fibers, The sewing thread has a weight loss of less than 50% when baked at 500°C for 1 hour, The sewing thread has the following formula: Flexing abrasion resistance value = flexing durability time during sliding test [s] / thickness of sewing thread [tex] The bending wear resistance value represented by the following formula (1) to (4) is in the range of 0.16 to 4.2, and the bending durability time in the sliding test is measured by the following steps (1) to (4). (1) One end of the sewing thread is fixed to one of two fixing parts having an inner dimension of 18 cm, and the other end of the sewing thread is passed through the eye of a needle of Japanese count #21, and then a load of 1.5 x the thickness (tex) g of the sewing thread is applied to the other fixing part to tension it; (2) The needle is fixed in its initial position by applying a load of 118 g so that the needle hole is positioned at the center of the two fixing parts and the height from the center of the needle hole to the fixing parts of the sewing thread is 1.5 cm; (3) The sewing thread is slid back and forth over a distance of 4 cm (8 cm per reciprocation) in the direction in which the sewing thread is stretched, with the initial position as the center, at a sliding speed of 2 reciprocations per second, and the time (s) from the start of sliding to the complete breakage of the sewing thread is measured; (4) Steps (1) to (3) are carried out five times, and the obtained times (s) are averaged to calculate the bending endurance time (s) of the sewing thread.

18. The method for producing glass cloth according to claim 17, wherein the weight loss of the sewing thread when fired at 500°C for 1 hour is less than 35%.

19. The method for producing glass cloth according to claim 17, wherein the sewing thread does not contain any metal fibers mixed therein.

20. The method for producing glass cloth according to claim 17, wherein the sewing yarn is not mixed with organic fibers.

21. The method for producing a glass cloth according to claim 17 or 18, further comprising a step of subjecting the glass cloth to a heat deoiling treatment after the sewing step.

22. The glass cloth is composed of glass yarns containing a plurality of filaments as warp and weft yarns, and the silicon (Si) content of the glass yarns is silicon dioxide (SiO ２ The method for producing a glass cloth according to claim 17 or 18, wherein the total mass of the glass cloth is 95.0 mass % to 100 mass % in terms of the total mass of the glass fiber.

23. The method for producing a glass cloth according to claim 21, wherein the heat deoiling treatment comprises a step of heat deoiling the glass cloth in the range of 500°C to 1500°C.

24. The method for producing a glass cloth according to claim 21, wherein the thermal deoiling treatment includes a step of performing the thermal deoiling treatment while transporting the glass cloth.

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