Storage method for glass cloth and glass cloth packaging

Abstract

To provide a storage method of glass cloth and a glass cloth package capable of maintaining dielectric characteristics of a glass cloth which has excellent dielectric characteristics.SOLUTION: A glass cloth is constituted with a glass yarn including a plurality of filaments being a warp and a weft, and the dielectric tangent in the glass cloth in 10GHz is equal to or less than 0.00200. A storage method includes storing the glass cloth under the atmosphere where the average dew point under the atmospheric pressure in a storage environment is equal to or less than 18°Cdp and the average temperature is equal to or less than 100°C. A package includes a packaging material and the glass cloth stored inside the packaging material, and the steam permeability of the packaging material measured under the condition of 40°C90%Rh is equal to or less than 8 g / (m2×24hr).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a method for storing glass cloth and a glass cloth package. This international application claims priority under Japanese Patent Application No. 2023-124261, filed on 31 July 2023, and Japanese Patent Application No. 2023-129381, filed on 8 August 2023, and the entire contents of said Japanese Patent Application are incorporated herein by reference. [Background technology]

[0002] Currently, information terminals such as smartphones are becoming more high-performance, and high-speed communication, exemplified by 5G communication, is progressing. Against this backdrop, for example, there is a demand for not only improved heat resistance in printed circuit boards for high-speed communication, but also for further improvement in the dielectric properties of their insulating materials (e.g., lower dielectric loss tangent). Similarly, there is a demand for improved dielectric properties in prepregs used as insulating materials for printed circuit boards, and in the glass yarns and glass cloths contained in said prepregs.

[0003] As a means of improving dielectric properties, for example, a method of producing prepregs using low-dielectric glass is known (see Patent Documents 1 and 2). More specifically, Patent Document 1 describes producing prepregs using glass yarn with a silicon dioxide (SiO2) composition of 98% by mass or more and 100% by mass or less. Patent Document 2 describes heat-treating quartz glass cloth for the purpose of further reducing dielectric loss tangent.

[0004] Patent Document 3 describes that the Si-OH groups on the surface of quartz glass are highly reactive, and in a high-temperature atmosphere in particular, they take in moisture through hydrogen bonding, which breaks the Si-O-Si bond and generates even more Si-OH groups (SiO2 + H2O ⇔ Si-OH), and these generated Si-OH groups worsen the dielectric loss tangent of the glass cloth (paragraph 0006). Therefore, with the aim of re-bonding the Si-OH groups to form Si-O-Si bonds and lowering the dielectric loss tangent of the glass cloth, the patent document describes heating the quartz glass cloth in a vacuum or in a gas with a dew point of 15°C or lower, with a maximum heating temperature of 100°C to 600°C, and a heating amount expressed as heating temperature (°C) × heating time (h) of 450 (°C·h) or more (Claim 1, etc.). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2018-127747 [Patent Document 2] Japanese Patent Publication No. 2021-63320 [Patent Document 3] Patent No. 7269416 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Patent Document 3 states that the reaction SiO2 + H2O ⇔ Si-OH does not have sufficient activation energy at temperatures below 100°C (paragraph 0025). Thus, conventionally, it has been thought that water has no effect on the dielectric loss tangent of glass cloth in the temperature range below 100°C. In this regard, the present inventors have discovered for the first time that even if the dielectric loss tangent of glass cloth is reduced during manufacturing by means such as those disclosed in Patent Documents 1 to 3, when glass cloth is stored for a long period of time, the formation of silanol groups by the above equilibrium reaction proceeds even in environments below 100°C, and the dielectric loss tangent of the glass cloth increases.

[0007] Therefore, one of the objectives of this disclosure is to provide a method for storing glass cloth and a glass cloth packaging that can maintain the dielectric properties of glass cloth having excellent dielectric properties. [Means for solving the problem]

[0008] Some embodiments of this disclosure are illustrated in the following sections [1] to

[57] . [1] This is a method for storing glass cloth. The above glass cloth is composed of glass threads containing multiple filaments as warp and weft threads, and the dielectric loss tangent of the above glass cloth at 10 GHz is 0.00200 or less. The above method is a method for storing glass cloth, which includes storing the glass cloth in an atmosphere where the average dew point under the atmospheric pressure of the storage environment is 18°C ​​dp or less and the average temperature is 100°C or less. [2] The method according to item 1, wherein the silicon (Si) content in the glass yarn is 95.0% to 100% by mass in terms of silicon dioxide (SiO2). [3] The above glass cloth has a surface treatment agent containing a silane coupling agent on its surface, according to the method described in item 1 or 2. [4] The above surface treatment agent is given by the following formula (1): X(R) 3-n SiY n ...(1) (In formula (1), X is an organic functional group having at least one of an amino group and a radically reactive unsaturated double bond group, Y is independently an alkoxy group, n is an integer between 1 and 3, and R is independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.) The method according to item 3, comprising a silane coupling agent as indicated by [the specified symbol]. [5] The method according to item 4, wherein the surface treatment agent comprises two or more silane coupling agents in which X is different in formula (1) above. [6] The method according to any one of items 3 to 5, wherein the surface treatment agent comprises two or more silane coupling agents with different molecular weights. [7] The method according to any one of items 3 to 6, further comprising the steps of surface-treating the glass cloth with a surface treatment agent containing a silane coupling agent before storage, and opening the fibers of the surface-treated glass cloth. [8] The method according to any one of items 1 to 7, wherein the dielectric loss tangent of the above glass cloth at 10 GHz is 0.00051 or more and 0.00200 or less. [9] The method according to any one of items 1 to 8, wherein the warp and / or weft density of the above-mentioned glass cloth is in the range of 66 to 120 threads / inch (= 66 to 120 threads / 25 mm).

[10] The method described above is the method described in any one of items 1 to 9, further comprising the step of heating the glass cloth to a temperature of 600°C or higher while transporting it by roll-to-roll before storage.

[11] The method according to any one of items 1 to 10, wherein the glass cloth described above is stored as a package, which is packaged in a box and / or a film-like packaging material.

[12] The method according to item 11, wherein the glass cloth is stored as a package in which it is wrapped in a film-like packaging material, and the thickness of the film-like packaging material is 50 μm or more.

[13] The method according to item 11 or 12, wherein the glass cloth is stored as a package in which it is wrapped in a film-like packaging material, and the film-like packaging material is an aluminum laminate film.

[14] The method according to any one of items 11 to 13, wherein the glass cloth is stored as a package wrapped in a film-like packaging material in a roll form around a hollow columnar core tube, and the film-like packaging material has recesses extending into the hollow portion from one or both ends of the core tube, or is an annular ring penetrating the hollow portion of the core tube.

[15] The method according to item 14, wherein the proportion of the volume occupied by the space inside the film-like packaging material within the volume of the hollow portion of the core tube is 50% or less of the volume of the hollow portion of the core tube.

[16] The above-mentioned film-like packaging material is an annular ring that penetrates the hollow portion of the core tube, as described in item 14 or 15.

[17] The method according to item 14 or 15, wherein the above-mentioned packaging is configured such that the glass cloth is sealed from the external environment by the film-like packaging material and the core tube.

[18] The water vapor transmission rate of the above core tube, measured under conditions of 40°C and 90% Rh, was 8 g / (m³). 2 The method described in any one of items 14-17, less than or equal to ×24hr.

[19] The above packaging material has a water vapor transmission rate of 8 g / m³ at a measurement temperature of 40°C and a measurement humidity of 90% Rh. 2 The method described in any one of items 11-18, less than or equal to ×24hr.

[20] The method according to any one of items 11 to 19, wherein the above-mentioned packaging is configured to dehumidify so as to maintain the mean dew point inside it at 18°Cdp or less. [twenty one] The method according to any one of items 1 to 20, including storing the items at a mean dew point of 13°Cdp or higher and 18°Cdp or lower under the atmospheric pressure of the above storage environment. [twenty two] The method according to any one of items 1 to 20, including storing the contents under the atmospheric pressure of the above storage environment at a mean dew point of -21°Cdp or lower. [twenty three] The method according to any one of items 11 to 19, wherein the above-mentioned packaging contains a desiccant. [twenty four] The amount of the above-mentioned desiccant to be enclosed is given by the following formula (2): WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ] / Amount of desiccant enclosed [g] ≤ 0.0030 ···(2) The method according to item 23, satisfying the following conditions: (In formula (2), WVTR is the water vapor transmission rate of the packaging material at a measurement temperature of 40°C and a measurement humidity of 90% Rh.) [twenty five] The method according to item 23 or 24, wherein the above-mentioned desiccant is at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccants, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate.

[26] The method according to any one of items 23 to 25, wherein the above-mentioned desiccant is a sheet-type desiccant.

[27] The method according to any one of items 1 to 26, wherein the atmosphere described above is dry air with a mean dew point of 18°Cdp or less, or a gas containing at least one selected from the group consisting of nitrogen, argon, and oxygen, with a mean dew point of 18°Cdp or less.

[28] The method described in any one of items 1 to 27, wherein the above atmosphere is reduced to below atmospheric pressure.

[29] The method according to any one of items 1 to 28, wherein the glass cloth is stored in a storage room with controlled dew point and temperature.

[30] The basis weight (mass of the glass cloth) of the above glass cloth is 8-25 g / m². 2 The method described in any one of items 1 to 29, which falls within the range of items 1 to 29.

[31] A glass cloth package comprising a packaging material and glass cloth stored inside the above packaging material, The above glass cloth is composed of glass threads containing multiple filaments as warp and weft threads. The dielectric loss tangent of the above glass cloth at 10 GHz is 0.00200 or less. The above packaging material is sealed. The water vapor transmission rate of the above packaging material, measured under conditions of 40°C and 90% Rh, was 8 g / (m³). 2 Glass cloth packaging with a shelf life of less than 24 hours.

[32] The glass cloth package according to item 31, wherein the packaging material is a box and / or a film.

[33] The glass cloth package according to item 32, wherein the packaging material is a film and the thickness of the film is 50 μm or more.

[34] The glass cloth package according to item 32 or 33, wherein the packaging material is a film and the film is an aluminum laminated film.

[35] The glass cloth package according to any one of items 32 to 34, wherein the glass cloth is packaged in a film in a state of a roll wound around a hollow columnar core tube, and the film has a recess extending into the hollow portion from one end or both ends of the core tube, or is an annular shape penetrating the hollow portion of the core tube.

[36] The glass cloth package according to item 35, wherein the ratio of the space inside the film to the volume of the hollow portion of the core tube is 50% or less of the volume of the hollow portion of the core tube.

[37] The glass cloth package according to item 35 or 36, wherein the film is an annular shape penetrating the hollow portion of the core tube.

[38] The glass cloth package according to item 35 or 36, wherein the package is configured such that the glass cloth is sealed from the external environment by the film and the core tube.

[39] The water vapor permeability of the core tube measured under the conditions of 40 °C and 90% Rh is 8 g / (m 2 ×24 hr) or less. The glass cloth package according to any one of items 35 to 38.

[40] The glass cloth package according to any one of items 31 to 39, wherein the dew point inside the packaging material is 18 °C dp or less.

[41] [[ID=D=39]]The glass cloth package according to any one of items 31 to 39, wherein the dew point inside the packaging material is 13 °C dp or more and 18 °C dp or less. [[ID=D=41]]

[42] A glass cloth packaging as described in any one of items 31 to 39, wherein the dew point inside the above packaging material is -21°Cdp or lower.

[43] A glass cloth package as described in any one of items 31 to 42, wherein the glass cloth is in roll form.

[44] A glass cloth package as described in any one of items 31 to 43, wherein a desiccant is sealed inside the above-mentioned packaging material.

[45] The amount of the above-mentioned desiccant to be enclosed is given by the following formula (2): WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ] / Amount of desiccant enclosed [g] ≤ 0.0030 ···(2) A glass cloth packaging as described in item 44, satisfying the following conditions: (In formula (2), WVTR is the water vapor transmission rate of the packaging material at a measurement temperature of 40°C and a measurement humidity of 90% Rh.)

[46] The glass cloth packaging according to item 44 or 45, wherein the above-mentioned desiccant is at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccants, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate.

[47] A glass cloth packaging as described in any one of items 44 to 46, wherein the above-mentioned desiccant is in sheet form.

[48] The glass cloth packaging according to any one of items 31 to 47, wherein the inside of the packaging material is filled with dry air with a dew point of 18°C ​​dp or less, or with a gas containing at least one selected from the group consisting of nitrogen, argon, and oxygen, with a dew point of 18°C ​​dp or less.

[49] A glass cloth packaging as described in any one of items 31 to 48, wherein the internal pressure of the packaging material is below atmospheric pressure.

[50] A glass cloth package according to any one of items 31 to 49, wherein the silicon (Si) content in the glass yarn is 95.0% to 100% by mass in terms of silicon dioxide (SiO2).

[51] A glass cloth package as described in any one of items 31 to 50, wherein the glass cloth is treated with a surface treatment agent containing a silane coupling agent.

[52] The above surface treatment agent is given by the following formula (1): X(R) 3-n SiY n ...(1) (In formula (1), X is an organic functional group having at least one of an amino group and a radically reactive unsaturated double bond group, Y is independently an alkoxy group, n is an integer between 1 and 3, and R is independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.) A glass cloth packaging according to item 51, comprising the silane coupling agent indicated above.

[53] The glass cloth packaging according to item 52, wherein the surface treatment agent comprises two or more silane coupling agents in formula (1) where X is different.

[54] The glass cloth packaging described in any one of items 51 to 53, wherein the surface treatment agent includes two or more silane coupling agents with different molecular weights.

[55] A glass cloth package as described in any one of items 31 to 54, wherein the dielectric loss tangent of the glass cloth at 10 GHz is 0.00051 or greater and 0.00200 or less.

[56] A glass cloth package as described in any one of items 31 to 55, wherein the warp and / or weft thread density of the glass cloth is in the range of 66 to 120 threads / inch (= 66 to 120 threads / 25 mm).

[57] The basis weight (mass of the glass cloth) of the above glass cloth is 8-25 g / m². 2 Glass cloth packaging as described in any one of items 31 to 56, which falls within the range of items 31 to 56. [Effects of the Invention]

[0009] According to this disclosure, it is possible to provide a method for storing glass cloth and a glass cloth packaging that can maintain the dielectric properties of glass cloth having excellent dielectric properties. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing a cross-sectional view of the glass cloth packaging material of this disclosure in the axial direction of the core tube. [Figure 2] Figure 2 is a schematic diagram illustrating the method for measuring the water vapor permeability of a core pipe. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure (hereinafter referred to as "these embodiments") will be described below. This disclosure is not limited to these embodiments, and various modifications are possible without departing from its essence. In these embodiments, numerical ranges described using "~" include the numbers before and after "~" as the lower and upper limits, respectively. In these embodiments, in numerical ranges described in stages, the upper or lower limit described in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In these embodiments, the upper or lower limit described in one numerical range may also be replaced with the values ​​shown in the examples. In these embodiments, the term "process" is included not only in the sense of an independent process, but also in the sense of a process that is not clearly distinguishable from other processes, as long as the function of the process is achieved.

[0012] How to store glass cloth The present disclosure relates to a method for storing glass cloth, which is composed of glass threads containing multiple filaments as warp and weft threads, and has a dielectric loss tangent of 0.00200 or less at 10 GHz. The method includes storing the glass cloth in an atmosphere where the mean dew point at atmospheric pressure is 18°C ​​dp or less and the mean temperature is 100°C or less. Conventionally, it has been thought that the reaction in which Si-O-Si bonds are cleaved by moisture and Si-OH groups are formed is not activated in the temperature range below 100°C, so no special consideration has been given to the storage method of glass cloth, and the dielectric loss tangent may increase over time. In this regard, by using the method of the present disclosure, the cleavage of Si-O-Si bonds and the formation of Si-OH groups due to moisture in the storage environment are suppressed, and thus the rise in the dielectric loss tangent of the glass cloth over time can be suppressed. In this disclosure, "suppression" does not mean that the dielectric loss tangent does not rise at all, but rather that the rise in the dielectric loss tangent is suppressed to a certain extent.

[0013] <Glass cloth> Glass cloth has a structure in which glass threads containing multiple glass filaments are used as warp and weft threads in a woven manner. Examples of weaving structures for glass cloth include plain weave, twill weave, satin weave, and twill weave. Among these, the plain weave structure is preferred.

[0014] The weft and warp thread counts of the glass cloth are preferably 10 to 120 threads / inch (=10 to 120 threads / 25 mm) independently of each other. The lower limit of the weft count is more preferably 20 threads / inch or more, 30 threads / inch or more, 40 threads / inch or more, 50 threads / inch or more, 60 threads / inch or more, or 66 threads / inch or more. The upper limit of the weft count is more preferably 110 threads / inch or less, or 100 threads / inch or less. If the weft count is within the above range, it is easier to obtain glass cloth of a desirable thickness. The weft and warp thread counts may be different.

[0015] The basis weight (mass) of the glass cloth is preferably 8 to 250 g / m².2 More preferably 8-100 g / m² 2 More preferably 8-80 g / m 2 , more preferably 8-50 g / m 2 Particularly preferred is 8-25 g / m 2 , or 8-23.2 g / m 2 Therefore, if the basis weight of the glass cloth is within the above range, it is easier to obtain glass cloth of a desirable thickness.

[0016] The thickness of the glass cloth is preferably greater than 0 and 60 μm or less. The upper limit of the glass cloth thickness is more preferably 55 μm or less, and even more preferably 50 μm or less. If the thickness of the glass cloth is within the above range, it is easier to obtain a glass cloth suitable as an insulating material. The lower limit of the glass cloth thickness is more preferably 5 μm or more, or 10 μm or more.

[0017] <Dielectric loss tangent of glass cloth> The glass cloth has a dielectric loss tangent of 0.00200 or less at 10 GHz, as measured by the method described in the examples. In such glass cloth, even at temperatures below 100°C, the dielectric loss tangent of the glass cloth increases over time due to the influence of water in the storage environment. Therefore, by keeping the average dew point temperature of the storage environment of the glass cloth below 18°Cdp, the increase in the dielectric loss tangent of the glass cloth can be suppressed. Here, "storage environment" refers to the atmosphere (gas) in which the glass cloth is in direct contact.

[0018] The dielectric loss tangent of the glass cloth at 10 GHz is preferably 0.00010 or more and 0.00200 or less. The upper limit of the dielectric loss tangent is 0.00200 or less, preferably 0.00160 or less, more preferably 0.00120 or less, even more preferably 0.00090 or less, even more preferably 0.00070 or less, particularly preferably 0.00050 or less, and particularly preferably 0.00040 or less. The lower limit of the dielectric loss tangent is preferably 0.00010 or more, 0.00015 or more, 0.00020 or more, 0.00028 or more, and 0.00030 or more. Because the dielectric loss tangent of the glass cloth is within the above range, it is easier to suppress the rise in the dielectric loss tangent as the glass cloth is less susceptible to the influence of moisture around the glass cloth in the storage environment.

[0019] <Glass thread> The glass yarn constituting the glass cloth is preferably obtained from low-dielectric glass as a raw material. More preferably, the silicon (Si) content of the low-dielectric glass yarn is 95.0% to 100% by mass in terms of SiO2. By using such glass yarn, the dielectric properties of the resulting glass cloth can be improved. Furthermore, with such glass yarn, the increase in the dielectric loss tangent of the glass cloth over time is significantly observed, making it easier to obtain an effect that suppresses the rise in dielectric loss tangent. From the viewpoint of improving dielectric properties, the Si content is preferably 99.0% by mass or more, more preferably 99.5% by mass or more, and even more preferably 99.9% by mass or more.

[0020] The average filament diameter of the glass filaments constituting the glass yarn 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, even more preferably 3.5 μm to 6.0 μm, and particularly preferably 3.5 μm to 5.0 μm. If the filament diameter is above the lower limit, it is easier to ensure the breaking strength of the filaments, and therefore less likely to occur in the resulting glass cloth. Also, if the filament diameter is below the upper limit, it is possible to prevent the mass of the glass cloth from becoming too large, making it easier to transport or process.

[0021] <Silane coupling agent> Preferably, the glass cloth has a surface treatment agent containing a silane coupling agent. More specifically, the glass threads (including glass filaments) constituting the glass cloth are preferably surface-treated with a surface treatment agent containing a silane coupling agent. The presence of a surface treatment agent in the glass cloth tends to improve its reactivity with the matrix resin. Furthermore, it becomes less susceptible to the effects of moisture during storage, thus more effectively suppressing the rise in dielectric loss tangent over time.

[0022] Examples of silane coupling agents include the following formula (1): X(R) 3-n SiY n ...(1) {In formula (1), X is an organic functional group having at least one of a radically reactive unsaturated double bond group, such as a radically reactive carbon-carbon double bond, and an amino group; Y is independently an alkoxy group; n is an integer between 1 and 3; and R is a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.} It is preferable to use the silane coupling agent indicated by [the specified symbol].

[0023] In formula (1), X is more preferably an organic functional group having one or more methacryloxy or acryloxy groups, from the viewpoint of reactivity with the matrix resin.

[0024] Regarding Y in formula (1) above, an alkoxy group having 1 to 5 carbon atoms (1, 2, 3, 4, or 5 carbon atoms) is preferred for stable treatment of the glass cloth.

[0025] As a surface treatment agent, the silane coupling agent shown in formula (1) may be used alone, or it may be used in mixture with two or more silane coupling agents in which X in formula (1) is different. Furthermore, the silane coupling agent shown in formula (1) can be used as a single agent or mixture thereof, for example, vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 5-hexenyltrimethoxysilane, etc.

[0026] The molecular weight of the silane coupling agent is preferably 100 to 600, more preferably 150 to 500, and even more preferably 200 to 450. In particular, it is especially preferable to use two or more silane coupling agents with different molecular weights. By treating the glass filament surface with two or more silane coupling agents with different molecular weights, the density of the treatment agent on the glass surface increases, and the reactivity with the matrix resin tends to improve further.

[0027] From the viewpoint of not inhibiting reactivity with the resin, it is preferable that the silane coupling agent is nonionic. Among nonionic silane coupling agents, those having at least one group selected from the group consisting of vinyl groups, methacryloxy groups, and acryloxy groups are preferred, and among these, silane coupling agents having at least one methacryloxy group or acryloxy group are particularly preferred. By not inhibiting reactivity with the resin, the heat resistance and reliability of the printed circuit board can be improved.

[0028] <Loss on ignition> The ignition loss of the glass cloth is preferably 0.01% by mass or more and less than 2.0% by mass, more preferably 0.01% by mass or more and less than 1.5% by mass, even more preferably 0.02% by mass or more and less than 1.0% by mass, even more preferably 0.03% by mass or more and less than 0.8% by mass, and particularly preferably 0.03% by mass or more and less than 0.3% by mass. When the ignition loss is within the above range, it is easier to obtain glass cloth that exhibits a low dielectric loss tangent. Here, the ignition loss is measured in accordance with JIS R3420.

[0029] <Storage of glass cloth> The method for storing glass cloth includes storing the glass cloth in an atmosphere where the mean dew point at the atmospheric pressure of the storage environment is 18°C ​​dp or lower and the mean temperature is 100°C or lower. Here, "storage environment" refers to the atmosphere in which the glass cloth is in direct contact. By controlling the storage environment of the glass cloth within the above range, it is possible to suppress the increase in the dielectric loss tangent of the glass cloth over time due to water present in the storage environment.

[0030] The storage period for the glass cloth, that is, the period during which the storage environment described in this disclosure is maintained, is not particularly limited, but is preferably 30 days to 5 years from the viewpoint of the time required for transporting the glass cloth and improving supply stability. The lower limit of the storage period is preferably 30 days or more, more preferably 90 days or more, even more preferably 180 days or more, even more preferably 365 days or more, and particularly preferably 730 days or more. Furthermore, from the viewpoint of reducing storage costs, the upper limit of the storage period for the glass cloth is preferably 5 years or less, more preferably 3 years or less. If the storage period is within the above range, the effects of maintaining the storage environment can be fully obtained. The longer the storage period, the more significant the effect of suppressing the rise in dielectric loss tangent can be obtained.

[0031] <Mean dew point in glass cloth storage environment> The method for storing glass cloth ensures that the average dew point of the storage environment under atmospheric pressure is 18°Cdp or lower. The average dew point refers to the average dew point over the storage period. Preferably, the dew point of the storage environment is controlled to remain at 18°Cdp or lower throughout the entire storage period. Maintaining an average dew point of 18°Cdp or lower prevents the dielectric loss tangent of the glass cloth from increasing over time. The average dew point is preferably between -50°Cdp and 18°Cdp. The lower limit of the average dew point may more preferably be -40°Cdp or higher, -32°Cdp or higher, -30°Cdp or higher, -20°Cdp or higher, -10°Cdp or higher, 0°Cdp or higher, 10°Cdp or higher, or 13°Cdp or higher. The upper limit of the average dew point, which can be arbitrarily combined with the lower limit mentioned above, is more preferably 15°Cdp or less, 10°Cdp or less, 5°Cdp or less, 0°Cdp or less, -5°Cdp or less, -10°Cdp or less, -15°Cdp or less, -20°Cdp or less, or -21°Cdp or less.

[0032] In the storage method for glass cloth, as long as the average dew point is 18°Cdp or lower, the dew point may exceed 18°Cdp for part of the storage period. Preferably, the storage environment is controlled so that the dew point is maintained at 18°Cdp or lower throughout the entire storage period. Known humidity control methods, humidity control media, humidity control mechanisms, and humidity control devices can be used to control the average dew point within the above range. For example, (1) using a desiccant, (2) replacing the ambient atmosphere with a gas containing a predetermined amount of moisture (e.g., a dry gas), (3) dehumidifying the ambient atmosphere by utilizing condensation at low temperatures, (4) reducing the pressure to bring the ambient atmosphere to a predetermined amount of moisture, and (5) combinations thereof.

[0033] Dew point control can be performed continuously or intermittently (periodically or irregularly) in an open or closed system, as long as the average dew point is controlled within the above range. For example, the control described in (1) to (5) above can be performed continuously in a closed system (e.g., inside a sealed packaging material), intermittently in a closed system (e.g., only on days in seasons or weather conditions where the dew point is likely to rise), or continuously control the change in dew point around the glass cloth in an open system. When maintaining the dew point by continuous humidity control, it is preferable to use a desiccant, replace with a dry gas, or use a dehumidifier.

[0034] <Desiccant> When using a desiccant to control the dew point, the type of desiccant is not limited as long as it can control the mean dew point within the above range. From the viewpoint of moisture absorption capacity, the desiccant is preferably at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccants, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate. In particular, it is preferable that it be at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, and calcined diatomaceous earth. Furthermore, from the viewpoint of occupied space and packaging form, it is preferable to use a sheet-type desiccant.

[0035] The amount of desiccant used is not limited as long as the mean dew point can be controlled within the above range, but it is preferable to use an appropriate amount depending on the desiccant's moisture absorption capacity (amount of moisture absorbed and absorption time), storage period, etc. Regarding the amount of moisture absorbed, it is preferable to use a sufficient amount or more. That is, it is preferable that the maximum amount of moisture that the desiccant can absorb is greater than the amount of moisture in the atmosphere. Alternatively, by periodically replacing the desiccant, it becomes easier to maintain constant storage environmental conditions for the glass cloth.

[0036] The amount of desiccant used becomes more important for longer storage periods. If the amount of desiccant is appropriate, it is easier to maintain the dew point of the storage environment and suppress the rise in dielectric loss tangent during long-term storage. The dew point of the storage environment, i.e., the amount of water vapor present inside the packaging, is affected not only by the water vapor permeability of the packaging material and the surface area of ​​the packaging, but also by the material of the packaging material, the external temperature and humidity of the storage environment, and the type, shape, and amount of desiccant. Therefore, it is difficult to estimate and enclose the appropriate amount of desiccant from the start of storage and construct the packaging accordingly. In particular, the water vapor permeability of the packaging material changes with the temperature and humidity of the surrounding environment, and the degree of this effect varies depending on the material of the packaging material, making it even more difficult to enclose the appropriate amount of desiccant. However, by using the following formula, when manufacturing packaging containing a desiccant, the water vapor permeability of the packaging material, the surface area of ​​the packaging, and the amount of desiccant can be controlled within a predetermined range, making it easier to control the rate at which the dew point inside the storage environment changes in relation to the external environment (dew point change rate). First, the amount of water vapor that can penetrate the packaging is expressed as water vapor transmission rate (WVTR) × packaging surface area × number of days of storage. Here, considering that WVTR changes under the influence of ambient temperature and humidity, the amount of water vapor that can penetrate the packaging can be simply expressed by the following formula, using WVTR as the water vapor transmission rate at a measurement temperature of 40°C and a measurement humidity of 90%Rh (dew point approximately 38°Cdp). (WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ])×(Storage environment external dew point [℃dp] / 38)×(Storage environment external temperature [℃] / 40)×Storage days Next, the maximum amount of moisture that can be removed from the inside of the packaging by a desiccant is affected by the type, shape, and amount of the desiccant, but can be simply expressed by the following formula. 0.26 × Amount of desiccant enclosed [g] In this case, it is preferable that the amount of water vapor that can penetrate into the packaging is less than or equal to the maximum amount of moisture that can be removed from the inside of the packaging by the desiccant, that is, that the following formula is satisfied. (WVTR[g / (m 2 ×24hr)] × package surface area [m 2]) × (External dew point of storage environment [°Cdp] / 38) × (External temperature of storage environment [°C] / 40) × Number of storage days ≤ 0.26 × Amount of desiccant enclosed [g] Furthermore, when the external ambient temperature is 30°C, the external dew point of the storage environment is 24°Cdp, and the storage period is 180 days, it is preferable to adjust the amount of desiccant so that the value obtained by the following formula (2) is 0.0030 or less. This makes it possible to seal in an appropriate amount of desiccant according to the composition of the packaging, and makes it easier to control the change in the dew point of the storage environment. WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ] / Amount of desiccant enclosed [g] ···(2) However, if the packaging is composed of two or more packaging materials with different water vapor permeability, the formula (2) "WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ]" refers to "WVTR[g / (m³)" for each packaging material. 2 ×24hr)] × package surface area [m 2 The sum of the values ​​obtained by formula (2) is more preferably 0.0023 or less, even more preferably 0.0012 or less, and particularly preferably 0.0005 or less. The value obtained by formula (2) may also be 0.

[0037] In this disclosure, the percentage change in the dew point inside a package containing a desiccant is defined by the following formula. Dew point change rate = (Dew point of the storage environment after 365 days of storage (°Cdp) - Initial dew point of the storage environment (°Cdp)) / (Average dew point of the external environment of the packaging material (°Cdp) - Dew point of the storage environment after 365 days of storage (°Cdp)) A smaller dew point change rate within the packaging indicates a greater effectiveness of controlling the storage environment with the packaging material and desiccant. The dew point change rate within the packaging is evaluated using the above formula, and the dew point change rate within the packaging 365 days after the start of storage of the glass cloth is preferably 3.0 or less, more preferably 1.0 or less, even more preferably 0.50 or less, even more preferably 0.30 or less, particularly preferably 0.10 or less, or 0.02 or less. The dew point change rate may also be a negative value.

[0038] <Dry gas> When using a dry gas to control the dew point, it is preferable to use a gas (dry gas) with a dew point temperature of 18°Cdp or lower. With such a dry gas, it is easier to control the atmosphere so that the average dew point of the glass cloth storage environment is 18°Cdp or lower. The dew point temperature of the dry gas is preferably between -60°Cdp and 18°Cdp. The lower limit of the dew point temperature of the dry gas may more preferably be -50°Cdp or higher, -40°Cdp or higher, or -30°Cdp or higher. The upper limit of the dew point temperature of the dry gas may more preferably be 15°Cdp or lower, 10°Cdp or lower, 5°Cdp or lower, 0°Cdp or lower, -5°Cdp or lower, -10°Cdp or lower, -15°Cdp or lower, -20°Cdp or lower, or -21°Cdp or lower.

[0039] As the dry gas, for example, dry air within the above dew point temperature range, or a gas containing at least one selected from the group consisting of nitrogen, argon, and oxygen within the above dew point temperature range, can be used. Dry air is preferred due to its ease of handling.

[0040] When using a dehumidifier to control the dew point, the dehumidifier is not limited as long as it can control the mean dew point within the above range. Examples include compressor-type dehumidifiers that utilize condensation at low temperatures, and desiccant-type (zeolite-type) dehumidifiers that regenerate the desiccant agent multiple times using heat.

[0041] To suppress changes in the dew point over time, it is preferable to store the glass cloth in a sealed storage environment. The sealing method should, in particular, suppress the inflow of moisture into the storage environment. Specific storage methods will be described later.

[0042] <Average temperature in the storage environment for glass cloth> Glass cloth is stored in an atmosphere where the average temperature of the storage environment is 100°C or lower. Maintaining an average temperature of 100°C or lower effectively suppresses the increase in the dielectric loss tangent of the glass cloth over time. The average temperature of the glass cloth storage environment is preferably between 0°C and 100°C. The upper limit of the average temperature is preferably 50°C or lower, more preferably 40°C or lower, even more preferably 35°C or lower, even more preferably 30°C or lower, and particularly preferably 25°C or lower. The lower limit of the average temperature may preferably be 10°C or higher, or 20°C or higher. Preferably, the temperature of the storage environment is controlled to be maintained at 100°C or lower throughout the entire storage period. More preferably, the temperature is controlled to be 40°C or lower, even more preferably 35°C or lower, even more preferably 30°C or lower, and particularly preferably 30°C or lower throughout the entire storage period. Preferably, the temperature of the storage environment is controlled to be 0°C or higher, 10°C or higher, or 20°C or higher throughout the entire storage period.

[0043] <Pressure in the storage environment of glass cloth> When reducing pressure to control the dew point, use atmospheric pressure (10°C). 5 It is preferable to control the pressure to be below atmospheric pressure. The method for controlling the pressure of the storage environment for glass cloth to be below atmospheric pressure is not limited as long as the mean dew point can be controlled within the above range, but known pressure reduction control methods, pressure reduction control media, pressure reduction control mechanisms, and pressure reduction control devices can be used, for example, a vacuum pump.

[0044] Maintaining atmospheric pressure can be done by known methods, as long as the storage environment for the glass cloth is maintained under reduced pressure below atmospheric pressure. For example, this may be done by continuously or intermittently (periodically or irregularly) reducing the pressure of the storage environment, or by sealing the glass cloth in a reduced-pressure packaging material to suppress changes in pressure. The atmospheric pressure around the glass cloth when storing or packaging it is preferably 10 4 Pa or less, more preferably 10 3It is below Pa. The lower limit of the atmospheric pressure is not particularly limited, but is preferably greater than 0 Pa or 10 Pa or more.

[0045] <Storage form> The storage method for glass cloth is not particularly limited as long as the above-mentioned storage environment is maintained, but examples include storage in a room such as a storage room, storage in a packaged body wrapped in packaging material, and combinations thereof. In this disclosure, the terms "packaging" and "packing" are used interchangeably to mean wrapping an object. Examples of packaging material include boxes and films. In each case, it is preferable to control the storage environment, i.e., the mean dew point and temperature of the atmosphere in which the glass cloth directly comes into contact, and optionally the pressure, within the above range. Furthermore, from the viewpoint of avoiding wrinkles in the glass cloth and reducing storage space, it is preferable to store the glass cloth in a roll. When stored in a roll, it is easy to minimize the area in contact between the storage environment and the external environment, and to reduce the internal air volume during packaging, thereby more effectively suppressing the rise in dielectric loss tangent over time.

[0046] For storage rooms and packaging materials used to store glass cloth, high airtightness is preferable from the viewpoint of easily maintaining the average dew point and temperature. In addition to high airtightness, or as an alternative, the storage rooms and packaging materials are preferably configured to dehumidify in order to maintain the average dew point inside (storage environment) at 18°Cdp or lower. That is, it is preferable that the storage room and packaging itself be equipped with the dew point control means described above. The average dew point inside (storage environment) is preferably -50°Cdp or higher and 18°Cdp or lower. The lower limit of the average dew point inside (storage environment) may more preferably be -40°Cdp or higher, -32°Cdp or higher, -30°Cdp or higher, -20°Cdp or higher, -10°Cdp or higher, 0°Cdp or higher, 10°Cdp or higher, or 13°Cdp or higher. The upper limit of the average dew point inside (storage environment), which can be arbitrarily combined with the lower limit mentioned above, is more preferably 15°C dp or less, 10°C dp or less, 5°C dp or less, 0°C dp or less, -5°C dp or less, -10°C dp or less, -15°C dp or less, -20°C dp or less, or -21°C dp or less.

[0047] <Packaging material> From the viewpoint of easily maintaining the dew point of the storage environment, the water vapor transmission rate of the packaging material (box, film, etc.) at a measurement temperature of 40°C and a measurement humidity of 90% Rh is preferably 8 g / (m³). 2 (×24hr) or less, more preferably 4 g / (m 2 (×24hr) or less, more preferably 2g / (m 2 (×24hr) or less, more preferably 1 g / (m³) 2 (×24hr) or less, particularly preferably 0.3 g / (m 2 (×24hr) or less, particularly preferably 0.1 g / (m 2 The water vapor permeability of the packaging material is 8 g / (m³) or less (×24hr). 2 By keeping it below (×24hr), the amount of moisture that permeates is reduced, making it easier to control the dew point. The lower limit of water vapor transmission is 0 g / (m³). 2 (×24hr) or more, for example, 0g / (m 2 It exceeds (x24hr).

[0048] When storing glass cloth in roll form as a package containing a box and / or film-like packaging material, it is preferable to enclose a desiccant within the package. It is even more preferable to enclose the desiccant between the roll and the packaging material. This allows the desiccant to absorb moisture from within the package and also absorb moisture that has seeped into the storage environment through the box and / or film-like packaging material during storage.

[0049] From the viewpoint of making it easier to maintain the dew point and temperature, it is preferable that the glass cloth is packaged in a box and / or film-like packaging material, and that the opening is sealed. Sealing can be done, for example, by heat-sealing the opening. Sealing means that the opening is tightly closed without any gaps, and that the temperature, dew point, and atmospheric pressure in the storage environment of the glass cloth can be controlled to be below a certain standard. Furthermore, the sealed state preferably means sealing in a way that prevents the intrusion of solids, liquids, and gases. By suppressing the intrusion of solids, liquids, and gases, it is easier to obtain the effect of suppressing the rise in the dielectric loss tangent of the glass cloth.

[0050] When using a box as packaging material, the box is not limited as long as its water vapor permeability meets the above range, but it must be designed to seal the opening, and examples include metal, plastic, wooden, cardboard boxes, or boxes made of a combination of these. From the viewpoint of easily meeting the above range in water vapor permeability and being easy to reuse, the material is preferably metal or plastic, and more preferably metal. Here, a box refers to a movable, airtight container that seals the glass cloth from the outside air. One or more rolls of glass cloth may be stored inside the box.

[0051] When using film as packaging material, the film is not limited as long as its water vapor permeability meets the above range, but examples include ceramic vapor-deposited film, aluminum vapor-deposited film, aluminum foil, and aluminum laminate film. From the viewpoint of easily meeting the above range in water vapor permeability, aluminum foil and aluminum laminate film are preferred. The thickness of the film is preferably 30 μm or more and 500 μm or less. The lower limit of the film thickness is preferably 50 μm or more, more preferably 70 μm or more, even more preferably 80 μm or more, and particularly preferably 90 μm or more. A thickness of 50 μm or more tends to reduce water vapor permeability and makes it less likely for pinholes to occur due to wrinkles or scratches. The upper limit of the film thickness is preferably 400 μm or less, 300 μm or less, 200 μm or less, or 170 μm or less.

[0052] Glass cloth is preferably stored as a packaged product wrapped in film in the form of a roll (also simply called a "glass cloth roll") wound around a hollow columnar core tube having a columnar cavity (hollow part) in the center. When handling glass cloth rolls, such as during transportation, it is common to insert a support rod into the hollow part of the core tube of the roll to lift it. From the viewpoint of maintaining the storage environment as described above, it is preferable to package glass cloth rolls with packaging material that has the minimum surface area; however, with this method, the hollow part of the core tube cannot be used when handling the glass cloth roll, making handling cumbersome. Therefore, from the viewpoint of ease of handling of glass cloth rolls, it is preferable that the glass cloth roll is configured such that the film-like packaging material has recesses extending into the hollow part from one or both ends of the core tube, or the film-like packaging material is ring-shaped (donut-shaped) and penetrates the hollow part of the core tube, so that a support rod can be inserted into the hollow part of the core tube. Alternatively, from the viewpoint of ease of handling of the glass cloth roll, it is preferable that the glass cloth is sealed from the external environment by a film-like packaging material and a core tube.

[0053] Figure 1 is a schematic diagram showing a cross-section of the glass cloth packaging body in the axial direction of the core tube according to the present disclosure. For example, as schematically shown in Figure 1(1a), the glass cloth packaging body 10 may have a hollow columnar core tube 11, glass cloth 12 wound around the core tube 11, and a film 13 that surrounds the entire core tube 11 and glass cloth 12. The film 13 is configured to have a recess 14 extending inward from one end of the core tube 11 into the hollow portion, so that a support rod can be inserted into the hollow portion. Also, as schematically shown in Figure 1(1b), the glass cloth packaging body 10 has an outer film 13a that covers the outside of the glass cloth 12 and a hollow inner film 13b that penetrates the inside of the hollow portion of the core tube 11, and the outer film 13a and the inner film 14b may be joined at a joint 15 by heat sealing or the like. As a result, the films 13a and 13b together have an annular shape that surrounds the entire core tube 11 and glass cloth 12. When the packaging material is ring-shaped, the external environment penetrates the hollow part of the core tube, allowing support rods to be inserted into the hollow part from both sides of the packaging, thus improving handling. The joining of the films is not particularly limited as long as the openings can be tightly sealed to eliminate gaps, for example, by heat sealing, tape, adhesive, etc. Alternatively, as schematically shown in Figure 1(1c), the film 13 covering the outside of the glass cloth 12 and the core tube 11 may be joined at a joint 15 located on the exposed outer surface of the core tube 11. In this way, the glass cloth 12 is sealed from the external environment by the film 13 and the core tube 11. In this configuration, because the external environment penetrates the hollow part of the core tube, support rods can be inserted into the hollow part from both sides of the packaging, and because there is no film inside the core tube, pinholes and the like are less likely to occur when inserting or removing the support rods and when lifting and transporting the roll, further improving handling. The method of joining the film-like packaging material to the core tube is not particularly limited as long as the opening can be tightly sealed and no gaps can be eliminated. For example, the opening can be sealed with tape, adhesive, or the like.

[0054] From the viewpoint of ease of inserting the support rod, the ratio of the volume of the hollow part of the core tube to the volume occupied by the space inside the film-like packaging is preferably 70% or less, more preferably 50% or less, even more preferably 30% or less, and particularly preferably 10% or less. The lower limit of the volume inside the packaging relative to the volume of the hollow part may be 0% or more. For example, in the embodiment schematically shown in Figure 1(1c), the volume inside the packaging relative to the volume of the hollow part is 0%.

[0055] <Core tube> The core tube around which the rolled glass cloth is wound has a columnar cavity (hollow section) in the center for ease of handling during transportation and post-processing. The core tube can be made of paper, resin, fiber-reinforced plastics (FRP), or metal, and paper, resin, or FRP are preferred from the viewpoint of preventing the incorporation of metal foreign matter into the glass cloth. The core tube generally has a certain thickness from the viewpoint of balancing weight and strength. In particular, glass cloth rolls are heavy because the glass cloth itself is heavy, while small diameter core tubes subject the glass cloth to strong bending, so efforts have been made to increase the diameter and reduce the weight of the core tube. Because the core tube is thicker than films, the permeability of water vapor through the core tube has not been considered until now. However, investigations revealed that even paper, resin, and FRP core tubes can be permeated by water vapor due to factors such as the overall thickness of the core tube being thin to reduce its weight, the core tube being constructed by combining thin materials, and the presence of seams where the materials are combined. Therefore, it is preferable to use a core tube with low water vapor permeability.

[0056] From the viewpoint of easily controlling the moisture content inside the packaging material, the water vapor transmission rate of the core tube measured under conditions of 40°C and 90% Rh is preferably 8 g / (m³). 2 (×24hr) or less, more preferably 4 g / (m 2 (×24hr) or less, more preferably 2g / (m 2 (×24hr) or less, more preferably 1 g / (m³) 2 (×24hr) or less, particularly preferably 0.3 g / (m2 (×24hr) or less, particularly preferably 0.1 g / (m 2 The water vapor permeability of the core tube is 8 g / (m³) or less (×24hr). 2 By keeping it below (×24hr), the amount of moisture that permeates is reduced, making it easier to control the dew point. The lower limit of water vapor transmission is 0 g / (m³). 2 (×24hr) or more, for example, 0g / (m 2 It exceeds ×24hr. Methods to control the water vapor permeability of the core tube to the above range include applying moisture-proof paint to the core tube, performing vapor deposition plating, increasing the thickness of the core tube, using a material with low water vapor permeability for the core tube, and wrapping the core tube with a film with low water vapor permeability.

[0057] <Package surface area> Glass cloth packaging, when wrapped in packaging material, is easier to maintain the storage environment if its surface area is small. The surface area of ​​the packaging is not limited as long as the dew point of the storage environment meets the scope of this disclosure, but is preferably 10 m². 2 Below, a more comfortable 7m 2 Further preferably 5m 2 More preferably 4m 2 The following applies: The lower limit of the packaging surface area is not limited as long as the glass cloth can be sealed from the external environment. In this disclosure, “packaging surface area” means, for example, the area of ​​the film if the glass cloth is sealed from the external environment by the film, the area of ​​the outer surface of the box if the glass cloth is sealed from the external environment by the box, and the sum of the area of ​​the film and the outer diameter side surface area of ​​the core tube separating the external environment from the storage environment if the glass cloth is sealed from the external environment by the film and core tube.

[0058] <Storage room> A storage room for glass cloth refers to an indoor space where the dew point and temperature are controlled. From the viewpoint of saving space, it is preferable to store glass cloth in rolls indoors where multiple rolls can be stored together. Glass cloth in roll form may also be stored in the storage room as packaged items, wrapped in boxes and / or film-like packaging materials.

[0059] Method for manufacturing glass cloth The method for manufacturing glass cloth used in the glass cloth storage method of this disclosure includes the step of weaving glass yarn containing a plurality of glass filaments as warp and weft threads to obtain glass cloth. The method for manufacturing glass cloth may further include the steps of heat-cleaning the glass yarn or glass cloth and treating the glass yarn or glass cloth with a surface treatment agent. The method for manufacturing glass cloth may optionally further include at least one of the steps of opening the glass cloth fibers and packaging the glass cloth in packaging material (box, film, etc.).

[0060] <Weaving process> The weaving method is not particularly limited as long as the weft and warp threads can be woven to achieve a predetermined weave structure. The preferred composition and structure of the glass yarn used, as well as the weave structure, are as described above.

[0061] <Heat deoiling process> The heat de-oiling process can be performed on glass yarn, or on woven glass cloth. In other words, the process of weaving glass yarn to obtain glass cloth may be performed before, during, or after the heat de-oiling process. The heat de-oiling process can be carried out by either (1) a method of heat de-oiling glass yarn or glass cloth (hereinafter simply referred to as "glass" in this process) at a relatively low temperature (e.g., less than 600°C) for a long period of time (e.g., 24 hours or more), or (2) a method of heat de-oiling glass at a relatively high temperature (e.g., 600°C to 1600°C) for a long or short period of time (e.g., less than 24 hours). From the viewpoint of obtaining glass cloth with excellent dielectric loss tangent, it is preferable to use method (2). In particular, glass cloth composed of glass yarn with a Si content of 95.0% to 100% by mass in terms of SiO2 may be heat de-oiled at a temperature of 600°C or higher. This makes it easier to lower the dielectric loss tangent of the glass cloth.

[0062] (1) When heating at a relatively low temperature, the temperature for degreasing by heating is preferably 100°C to 500°C, more preferably 250°C to 450°C, and even more preferably 350°C to 450°C. The heating time in degreasing by heating in case (1) can be appropriately selected, for example, preferably 24 hours to 300 hours, more preferably 48 hours to 200 hours, and even more preferably 72 hours to 150 hours. If the degreasing temperature and time are within the above ranges, the adhesive adhering to the glass can be easily removed.

[0063] On the other hand, (2) when heating at a relatively high temperature, the temperature for degreasing by heating is preferably 600°C to 1500°C, more preferably 800°C to 1300°C, and even more preferably 900°C to 1100°C. If the degreasing by heating temperature is 600°C or higher, organic matter such as adhesive residue adhering to the glass can be easily removed, making it easier to lower the dielectric loss tangent of the glass cloth and shortening the removal time. On the other hand, if the degreasing by heating temperature is 1500°C or lower, the devitrification phenomenon of the glass can be easily suppressed, and the reduction in strength of the glass cloth can be effectively prevented. In addition, the heating time in degreasing by heating in case (2) can be appropriately selected, for example, preferably 3 seconds to 72 hours, more preferably 3 seconds to 12 hours, even more preferably 3 seconds to 2 hours, particularly preferably 3 seconds to 10 minutes, and particularly preferably 3 seconds to 300 seconds.

[0064] In thermal degreasing, known heating methods, heating media, heating mechanisms, heating devices, and heating components can be used as heating means, as long as they allow for suitable control of the thermal degreasing temperature. For example, (1) a method of heating glass in a heating furnace, (2) a method of bringing glass into contact with a heating element, (3) a method of applying high-temperature steam to glass, etc. Heating can be carried out sequentially or continuously, in a closed system or an open system, or in a combination of a closed system and an open system.

[0065] In the case of a closed system, from the viewpoint of optimal heating by heating means, it is preferable to place the glass inside the heating furnace, and in this case, from the viewpoint of storage space and heating range, it is preferable to heat the glass cloth while storing it in a roll. Furthermore, from the viewpoint of increasing the efficiency of organic matter removal and shortening the time for organic matter removal, it is also preferable to heat the glass while transporting it inside the heating furnace.

[0066] In the case of an open system, it is preferable to heat the glass while transporting it roll-to-roll, from the viewpoint of the heating surface area. As mentioned above, the heating temperature is preferably 600°C to 1500°C, more preferably 800°C to 1300°C, and even more preferably 900°C to 1100°C. The glass can be transported, for example, by an unwinding mechanism and a winding mechanism.

[0067] Various heating means for the heating furnace include electric heaters and burners, with gas-powered single-radiant tube burners or electric heaters being preferred. Multiple means may be combined for heating.

[0068] From the viewpoint of heating efficiency, the heating furnace is preferably equipped with means for discharging the gas generated in the heating furnace and / or means for air circulation. The gas discharge means may be a nozzle, gas pipe, small hole, gas vent valve, etc. The air circulation means may be a fan, air conditioning equipment, etc.

[0069] The heating furnace may be of either a batch type, capable of housing glass (e.g., rolls of glass cloth) and heating it at a predetermined ambient temperature, or a continuous type, capable of heating the glass while continuously passing it through the furnace (e.g., heating while transporting it roll-to-roll). A continuous type heating furnace is preferred in order to efficiently remove organic matter adhering to the glass surface.

[0070] As a method for heating the glass, the above-mentioned heating furnace may be used, but from the viewpoint of low running costs, it may also be heated by bringing a component heated to a predetermined temperature into contact with the glass.

[0071] The shape of the contact member is not particularly limited as long as the heating and de-oiling temperature can be appropriately controlled, but a roll shape is preferred due to the ease of glass transport (heating roll method). As a member capable of heating glass in a roll shape, a roll that is heated by induction heating is preferred, as it can be used in a high-temperature range and has relatively little temperature variation in the width direction. When heating glass with a contact member, it is assumed that the temperature of the contact member and the surface temperature of the glass are approximately equal.

[0072] As glass is continuously heated, carbides may adhere to the heating roll. To remove the carbides adhering to the heating roll, the above heating roll system preferably includes a mechanism for removing the adhering foreign matter, such as a blade.

[0073] <Surface treatment process> The surface treatment process can be performed on glass yarn, or on woven glass cloth. In other words, the process of weaving glass yarn to obtain glass cloth may be performed before, during, or after the surface treatment process. The surface treatment process may include, for example, a coating step of applying a silane coupling agent to the surface of the glass yarn or glass cloth (hereinafter simply referred to as "glass" in this process) with a treatment solution at a concentration of 0.1% to 0.5% by mass. The surface treatment process may further include a fixing step of fixing the silane coupling agent to the surface of the glass by heating and drying. This makes it easier to suitably surface treat the glass.

[0074] Methods for applying the treatment solution to the glass in the coating process include (a) immersing or passing the glass through the treatment solution stored in a bath (hereinafter referred to as the "immersion method"), and (b) applying the treatment solution to the glass using a roll coater, die coater, or gravure coater. When using the immersion method, it is preferable to select an immersion time of 0.5 seconds to 1 minute for the glass in the treatment solution. When using the immersion method, the glass can be passed through the treatment solution at a transport speed of 10 m / min to 50 m / min while applying a predetermined tension to the glass (for example, 100 N to 250 N). After applying the treatment solution to the glass, 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 surface treatment agent to the glass surface, it is preferable to immerse the glass cloth in the surface treatment solution and then squeeze it with a rubber roller under constant pressure.

[0075] The concentration of the surface treatment agent in the treatment solution is preferably 0.1% to 0.5% by mass, more preferably 0.1% to 0.45% by mass, and even more preferably 0.1% to 0.4% by mass, based on the total mass of the treatment solution. This makes it easier to surface treat the glass more effectively.

[0076] In the fixing process, the heating and drying temperature is preferably 80°C or higher, and more preferably 90°C or higher, so that the reaction between the silane coupling agent and the glass can proceed sufficiently. Furthermore, the heating and drying temperature is preferably 300°C or lower, and more preferably 180°C or lower, in order to prevent deterioration of the organic functional groups of the silane coupling agent.

[0077] <Opening process> The method for manufacturing glass cloth may further include a step of opening the glass cloth fibers. For example, the fiber-opening method in the glass cloth process may involve using spray water (high-pressure water opening), a vibro-washer, ultrasonic water, or a mangle. The composition of the glass cloth usually does not change before and after opening.

[0078] <Packaging process> The method for manufacturing glass cloth may further include a step of packaging the glass cloth in packaging material, such as film or a box. This makes it easier to maintain the storage environment of the glass cloth. Details of the packaging material have been described above and will be omitted here. In the packaging step, it is preferable to pre-control the dew point and temperature of the environment in which the glass cloth is in direct contact, as well as optionally the pressure, to match the storage environment of this disclosure before packaging. Details of the storage environment have been described above and will be omitted here. As for sealing methods, for example, a method of wrapping the glass cloth in film and heat-sealing the opening, a method of placing the glass cloth in a box and sealing the opening tightly to eliminate gaps, or a method of sealing the opening with tape, etc., can be used.

[0079] When packaging glass cloth in a roll wound around a hollow columnar core tube with film, for example, the glass cloth roll can be covered with film, the opening can be heat-sealed, and the excess film can be pushed into the hollow part from one or both ends of the core tube to form a recess extending into the hollow part from one or both ends of the core tube. As a method of packaging in an annular shape with the hollow part of the core tube passing through, a tubular film can be inserted into the hollow part of the core tube of the glass cloth roll, the glass cloth roll can be covered with another film, and the tubular film and the tubular film passing through the hollow part can be heat-sealed to seal the opening. As a method of packaging by joining the film and the core tube, for example, the film can be attached to the surface of the core tube without any gaps using tape.

[0080] The above steps do not necessarily have to be carried out in a manner that can be distinguished as separate steps; multiple steps can be carried out together (simultaneously). Furthermore, the method for manufacturing glass cloth can include any steps other than those described above. For example, a slitting step can be included after the fiber opening step. Also, if possible, the order of the above steps can be changed.

[0081] Glass cloth packaging The glass cloth packaging of this disclosure includes a packaging material and glass cloth housed inside the packaging material. The glass cloth is composed of glass threads containing multiple filaments as warp and weft threads, and has a dielectric loss tangent of 0.00200 or less at 10 GHz. The packaging material housing the glass cloth is sealed, and the water vapor transmission rate of the packaging material at a measurement temperature of 40°C and a measurement humidity of 90% Rh is 8 g / (m²). 2 It is less than or equal to ×24hr. Conventionally, it has been thought that in the temperature range below 100°C, the reaction in which Si-O-Si bonds are cleaved by moisture and Si-OH groups are formed is not activated, so even if glass cloth with a dielectric loss tangent of 0.00200 or less at 10 GHz is stored for a long period of time in the temperature range below 100°C, the dielectric loss tangent of the glass cloth will not change over time. For this reason, the storage method of glass cloth has not been given special consideration, and even glass cloth with a low dielectric loss tangent at the time of manufacture may have an increase in dielectric loss tangent over time. In this regard, the glass cloth packaging of this disclosure suppresses the cleavage of Si-O-Si bonds and the formation of Si-OH groups due to moisture entering the storage environment from the external environment, so it is possible to suppress the increase in the dielectric loss tangent of the glass cloth over time. In this disclosure, "suppression" does not mean that the dielectric loss tangent does not increase at all, but rather that the increase in dielectric loss tangent is suppressed to a certain extent.

[0082] <Glass cloth> Details regarding the glass cloth, the dielectric loss tangent of the glass cloth, the glass yarn, the silane coupling agent, and the loss on ignition in the glass cloth packaging are as described in the sections "Glass Cloth" to "Loss on Ignition" in the above-mentioned "Storage Method for Glass Cloth," and therefore these descriptions shall be applied to the glass cloth packaging.

[0083] <Packaging material> The packaging material can contain and seal glass cloth. The water vapor transmission rate of the packaging material (box, film, etc.), measured at 40°C and 90% Rh, is 8 g / m². 2The temperature is less than or equal to ×24hr. Sealing means that the opening is tightly closed without any gaps, and that the temperature, dew point, and atmospheric pressure inside the glass cloth packaging can be controlled to be below a certain standard. Furthermore, the sealed state preferably means sealing in a way that prevents the intrusion of solids, liquids, and gases. By suppressing the intrusion of solids, liquids, and gases, the effect of suppressing the rise in the dielectric loss tangent of the glass cloth described in this disclosure is easily obtained. The packaging material is not limited as long as it satisfies the above configuration, but examples include film and box-shaped packaging materials.

[0084] <Water vapor transmission rate> The packaging material has a water vapor transmission rate of 8 g / m³ at a measurement temperature of 40°C and a measurement humidity of 90% Rh. 2 The moisture content is less than or equal to 24 hours. With such packaging materials, it is possible to control the amount of moisture inside the packaging material and suppress the increase in the dielectric loss tangent of the glass cloth over time due to the water present in the packaging material. From the viewpoint of being able to easily control the amount of moisture inside the packaging material, the water vapor transmission rate of the packaging material at a measurement temperature of 40°C and a measurement humidity of 90% Rh is preferably 8 g / (m²). 2 (×24hr) or less, more preferably 4 g / (m 2 (×24hr) or less, more preferably 2g / (m 2 (×24hr) or less, more preferably 1 g / (m³) 2 (×24hr) or less, particularly preferably 0.3 g / (m 2 (×24hr) or less, most preferably 0.1 g / (m 2 The water vapor permeability of the packaging material is 8 g / (m³) or less (×24hr). 2 By keeping the water vapor permeability below 24 hours, the amount of moisture that permeates is reduced, making it easier to control the moisture content inside the packaging material. The lower limit of water vapor permeability is 0 g / (m³). 2 (×24hr) or more, for example, 0g / (m 2 It exceeds (x24hr).

[0085] <film> Film can also be used as the packaging material. While not limited as long as the water vapor permeability meets the above range, examples include ceramic vapor-deposited film, aluminum vapor-deposited film, aluminum foil, and aluminum laminate film. Aluminum foil and aluminum laminate film are preferred from the viewpoint of easily meeting the above range of water vapor permeability. The film thickness is preferably 30 μm to 500 μm. The lower limit of the film thickness is preferably 50 μm or more, more preferably 70 μm or more, even more preferably 80 μm or more, and particularly preferably 90 μm or more. A thickness of 50 μm or more tends to result in lower water vapor permeability and reduces the likelihood of pinholes caused by wrinkles or scratches. The upper limit of the film thickness is preferably 400 μm or less, 300 μm or less, 200 μm or less, or 170 μm or less.

[0086] It is preferable that the glass cloth is packaged in a film in the form of a roll (also simply called a "glass cloth roll") wound around a hollow columnar core tube having a columnar cavity (hollow part) in the center. For the same reasons as described in the "Packaging Material" section of the "Storage Method for Glass Cloth" above, it is preferable that the film has recesses extending into the hollow part from one or both ends of the core tube, or that the film-like packaging material is ring-shaped (donut-shaped) and penetrates the hollow part of the core tube, so that a support rod can be inserted into the hollow part of the core tube. Alternatively, it is preferable that the glass cloth is sealed from the external environment by the film-like packaging material and the core tube. Specific examples of these are schematically shown in Figures 1(1a) to (1c), as described above.

[0087] From the viewpoint of ease of inserting the support rod, the ratio of the volume of the hollow part of the core tube to the volume occupied by the space inside the film-like packaging is preferably 70% or less, more preferably 50% or less, even more preferably 30% or less, and particularly preferably 10% or less. The lower limit of the volume inside the packaging relative to the volume of the hollow part may be 0% or more. For example, in the embodiment schematically shown in Figure 1(1c), the volume inside the packaging relative to the volume of the hollow part is 0%.

[0088] <Core tube> For the same reasons as described above in the section on "Storage Method for Glass Cloth" regarding the "Core Tube," the core tube is preferably made of paper, resin, or FRP. Furthermore, the water vapor transmission rate of the core tube, measured at 40°C and 90% Rh, is preferably 8 g / (m²). 2 (×24hr) or less, more preferably 4 g / (m 2 (×24hr) or less, more preferably 2g / (m 2 (×24hr) or less, more preferably 1 g / (m³) 2 (×24hr) or less, particularly preferably 0.3 g / (m 2 (×24hr) or less, particularly preferably 0.1 g / (m 2 The lower limit of water vapor transmission is 0 g / (m³). 2 (×24hr) or more, for example, 0g / (m 2 It exceeds (x24hr).

[0089] <Box-shaped packaging material> Box-shaped packaging materials can also be used. While not limited as long as the water vapor permeability meets the above range, the packaging must be designed to seal the opening. Examples include metal, plastic, wooden, cardboard boxes, or combinations of these materials. From the viewpoint of easily meeting the above water vapor permeability range and ease of reuse, the material is preferably metal or plastic, more preferably metal. Here, "box" refers to a movable, airtight container that seals the glass cloth from the outside air. One or more rolls of glass cloth may be stored inside the box.

[0090] <Package surface area> For the same reasons as described above in the section on "Core Tube" in the "Storage Method for Glass Cloth," the surface area of ​​the packaging is not limited as long as the dew point of its storage environment meets the scope of this disclosure, but preferably 10 m². 2 Below, a more comfortable 7m 2 Further preferably 5m 2 More preferably 4m 2The following applies: The lower limit of the packaging surface area is not limited as long as the glass cloth can be sealed from the external environment.

[0091] <Dew point inside glass cloth packaging> The glass cloth packaging preferably has a dew point of 18°Cdp or less under atmospheric pressure inside the packaging material. Unless otherwise specified in this disclosure, dew point refers to the dew point under atmospheric pressure in the storage environment. A dew point of 18°Cdp or less under atmospheric pressure inside the packaging material can more effectively prevent the dielectric loss tangent of the glass cloth from increasing over time. The dew point is preferably between -50°Cdp and 18°Cdp. The lower limit of the dew point may more preferably be -40°Cdp or higher, -32°Cdp or higher, -30°Cdp or higher, -20°Cdp or higher, -10°Cdp or higher, 0°Cdp or higher, 10°Cdp or higher, or 13°Cdp or higher. The upper limit of the dew point, which can be arbitrarily combined with the lower limit mentioned above, is more preferably 15°C dp or less, 10°C dp or less, 5°C dp or less, 0°C dp or less, -5°C dp or less, -10°C dp or less, -15°C dp or less, -20°C dp or less, or -21°C dp or less.

[0092] Methods for controlling the dew point within the above range include using known humidity control methods, humidity control media, humidity control mechanisms, and humidity control devices. For example, these can be: (1) using a desiccant; (2) replacing the atmosphere inside the packaging material with a gas containing a predetermined amount of moisture (e.g., a dry gas); (3) dehumidifying the atmosphere inside the packaging material by utilizing condensation at low temperatures; (4) reducing the pressure to bring the atmosphere inside the packaging material to a predetermined amount of moisture; and (5) combinations thereof. For example, by performing the above control methods (1) to (5) and sealing the packaging material, it becomes easier to obtain an effect that suppresses the rise in dielectric loss tangent.

[0093] When using a dehumidifier to control the dew point, the dehumidifier is not limited as long as it can control the dew point within the above range. Examples include compressor-type dehumidifiers that utilize condensation at low temperatures, and desiccant-type (zeolite-type) dehumidifiers that regenerate the desiccant agent multiple times using heat.

[0094] <Desiccant> It is preferable to enclose a desiccant inside the glass cloth packaging. This allows the desiccant to absorb moisture from inside the packaging and also absorb moisture that has permeated the packaging and entered the packaging during storage.

[0095] From the viewpoint of moisture absorption capacity, the desiccant is preferably at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccants, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate. In particular, it is preferable that it be at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, and calcined diatomaceous earth. Furthermore, from the viewpoint of occupied space and packaging form, it is preferable to use a sheet-type desiccant.

[0096] The amount of desiccant used is not limited, but it is preferable to use an appropriate amount depending on the desiccant's moisture absorption capacity (amount of moisture absorbed and absorption time), storage period, etc. Regarding the amount of moisture absorbed, it is preferable to use a sufficient amount or more. That is, it is preferable that the maximum amount of moisture that the desiccant can absorb is greater than the amount of moisture in the atmosphere.

[0097] As described in the section on "Desiccant" in the above-mentioned "Storage Method for Glass Cloth," the amount of desiccant to be enclosed is preferably 0.0030 or less, more preferably 0.0023 or less, even more preferably 0.0012 or less, and particularly preferably 0.0005 or less, as determined by the following formula (2). The value determined by the following formula (2) may be 0. WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ] / Amount of desiccant enclosed [g] ···(2) {In equation (2), WVTR is the water vapor transmission rate at a measurement temperature of 40°C and a measurement humidity of 90% Rh.}

[0098] As described in the section on "Desiccant" in the above-mentioned "Method for Storing Glass Cloth," the dew point change rate inside the packaging containing the desiccant is preferably 3.0 or less, more preferably 1.0 or less, even more preferably 0.50 or less, even more preferably 0.30 or less, particularly preferably 0.10 or less, or 0.02 or less. The dew point change rate may also be a negative value.

[0099] <Dry gas> When using a dry gas to control the dew point inside the packaging material, it is preferable to use a gas (dry gas) with a dew point temperature of 18°Cdp or lower. With such a dry gas, it is easier to control the atmosphere inside the packaging material so that the dew point is 18°Cdp or lower. The dew point temperature of the dry gas is preferably between -60°Cdp and 18°Cdp. The lower limit of the dew point temperature of the dry gas may more preferably be -50°Cdp or higher, -40°Cdp or higher, or -30°Cdp or higher. The upper limit of the dew point temperature of the dry gas may more preferably be 15°Cdp or lower, 10°Cdp or lower, 5°Cdp or lower, 0°Cdp or lower, -5°Cdp or lower, -10°Cdp or lower, -15°Cdp or lower, -20°Cdp or lower, or -21°Cdp or lower.

[0100] As the dry gas, for example, dry air within the above dew point temperature range, or a gas containing at least one selected from the group consisting of nitrogen, argon, and oxygen within the above dew point temperature range, can be used. Dry air is preferred due to its ease of handling.

[0101] <Temperature inside glass cloth packaging> The glass cloth packaging preferably has a temperature of 100°C or lower inside the packaging material. A temperature of 100°C or lower effectively suppresses the increase in the dielectric loss tangent of the glass cloth over time during long-term storage (e.g., 30 days or more). The temperature of the glass cloth storage environment (inside the packaging material) is preferably between 0°C and 100°C. The upper limit of the average temperature is preferably 50°C or lower, more preferably 40°C or lower, even more preferably 35°C or lower, even more preferably 30°C or lower, and particularly preferably 25°C or lower. The lower limit of the average temperature is preferably 10°C or higher, or may be 20°C or higher.

[0102] <Pressure inside glass cloth packaging> When reducing pressure to control the dew point inside the packaging material, atmospheric pressure (10°C) is used. 5 It is preferable to control the pressure to be below atmospheric pressure (Pa). The method for controlling the pressure inside the packaging material to be below atmospheric pressure is not limited as long as the dew point can be controlled within the above range, but known pressure reduction control methods, pressure reduction control media, pressure reduction control mechanisms, and pressure reduction control devices can be used, for example, a vacuum pump.

[0103] For example, by controlling the pressure inside the packaging material to be reduced to below atmospheric pressure and sealing the packaging material, it becomes easier to suppress the rise in dielectric loss tangent. The atmospheric pressure around the glass cloth when storing or packaging the glass cloth is preferably 10 4 Pa or less, more preferably 10 3 It is below Pa. The lower limit of the atmospheric pressure is not particularly limited, but is preferably greater than 0 Pa or 10 Pa or more.

[0104] <Storage period> The storage period for glass cloth, that is, the period during which the sealing of the packaging material in the glass cloth packaging of this disclosure is maintained, is not particularly limited, but is preferably 30 days to 5 years from the viewpoint of the time required for transporting the glass cloth and improving supply stability. The lower limit of the storage period is preferably 30 days or more, more preferably 90 days or more, even more preferably 180 days or more, even more preferably 365 days or more, and particularly preferably 730 days or more. Furthermore, from the viewpoint of reducing storage costs, the upper limit of the storage period for glass cloth is preferably 5 years or less, more preferably 3 years or less. If the storage period is within the above range, the effects of using the glass cloth packaging of this disclosure can be fully obtained. The longer the storage period, the more significant the effect of suppressing the rise in dielectric loss tangent can be obtained.

[0105] Method for manufacturing glass cloth packaging The glass cloth packaging described herein can be manufactured by packaging glass cloth, which is manufactured by the method described in the section above titled "Method for Manufacturing Glass Cloth," with the method described in the section above titled "Packaging Process," and these descriptions shall be incorporated into the method for manufacturing the glass cloth packaging. [Examples]

[0106] Measurement and Evaluation Methods <Method for measuring fabric weight> The basis weight of the glass cloth was determined by cutting the glass cloth to a predetermined size and dividing its weight by the sample area. In this example or comparative example, the glass cloth was 10 cm 2 The process of cutting the glass cloth to the specified size and measuring its weight was repeated 10 times, and the average value was used as the basis weight for each piece of glass cloth.

[0107] <Method for measuring converted thickness> Glass cloth is a discontinuous planar material with air between the glass fibers. Therefore, the equivalent thickness was calculated by dividing the basis weight (mass of the cloth) of each glass cloth by the density of the glass. Specifically, the following formula: Equivalent thickness (μm) = Basis weight (g / m²) 2 )÷Density(g / cm 3 ) The converted thickness was calculated using this method. This converted thickness value was used for measurement using the resonance method.

[0108] <Method for measuring dielectric loss tangent> The dielectric loss tangent of each glass cloth was determined in accordance with IEC 62562. Specifically, glass cloth samples, sampled to the size required for measurement in a split-cylinder resonator, were stored in a constant temperature and humidity oven at 23°C and 50%RH for at least 8 hours. After storage, the dielectric properties at 10 GHz were measured for the samples using a split-cylinder resonator (EM Labs) and an impedance analyzer (Agilent Technologies). Measurements were performed five times for each sample, and the average value was calculated. The above-mentioned converted thickness was used as the thickness of each sample. Note that IEC 62562 mainly specifies a method for measuring the dielectric properties in the microwave band of fine ceramic materials used in microwave circuits.

[0109] <Method for measuring the loss on ignition of glass cloth> The ignition loss value of the glass cloth was determined in accordance with JIS R3420.

[0110] <Method for measuring temperature and dew point> Temperature and dew point were measured using a Vaisala DM70 handheld dew point meter. Depending on the dew point to be measured, a DMP74A probe or a DMP74B probe and an MI70 indicator were used to measure the dew point under the atmospheric pressure of the storage environment. Specifically, the DMP74A probe was used when the dew point exceeded -30°Cdp, and the DMP74B probe was used when the dew point was below -30°Cdp. The average temperature and average dew point were determined by averaging the temperature and dew point measured every 3 hours with the DM70.

[0111] <Method for measuring pressure> The pressure inside the box was measured by visually reading the pressure gauge attached to the box.

[0112] <Method for measuring the water vapor permeability of packaging materials and core tubes> Measurement method A: For plastic films, plastic sheets, and multilayer materials containing plastic, where the packaging material thickness is 2 mm or less. In accordance with JIS K7130 and JIS K7129-1, the thickness and water vapor permeability of the packaging material were measured. The measurement was carried out 3 times for each sample, and the average value was taken as the thickness and water vapor permeability of the packaging material. Note that test pieces with no wrinkles, creases, or pinholes and uniform thickness were used, as visually inspected. · Equipment: Water Vapor Permeameter L80-5000 (manufactured by Lyssy, ISO-PE-Z91) · Thickness gauge: ID-C1012C (manufactured by Mitutoyo, ISO-PE-Z78) · Temperature and humidity: 40°C, 90% Rh · Measurement area: approximately 50 cm 2 · Reference sample: PET with a thickness of 19 μm (25.5 g / (m 2 × 24 h)) · Measurement direction: Permeation from the surface where the glass cloth is on the outside during packaging

[0113] Measurement method B: When the packaging material is not subject to measurement method A and is other than the core tube For packaging materials not subject to measurement method A, when the outside of the packaging material was set at a humidity of 90% Rh at a temperature of 40°C and the air inside was kept dry and sealed, the weight of water vapor that penetrated into the inside of the packaging material was measured. The water vapor weight was per 24 hours of permeation time and per 1 m of the outside surface area of the packaging material 2It was calculated per hit. Specifically, dry air with a dew point of -30°C dp was enclosed inside the packaging material, 800 g of a desiccant of Class 1 A of JIS Z 0701 (Desiccant for Packaging) or of a quality equivalent to or higher than this was put in, the temperature and dew point were measured, and it was sealed. Here, when the desiccant does not contain 800 g, it is measured so that the weight of the enclosed desiccant can be known, and the desiccant is enclosed so as to have a capacity of half or more of the internal volume of the packaging material. Subsequently, the sealed packaging material was placed in a thermo-hygrostat at 40°C and 90% Rh, and the packaging material was stored in the thermo-hygrostat for an appropriate time of 48 hours or more. After a certain time (this time is referred to as the retention time in the thermo-hygrostat), the packaging material was taken out of the thermo-hygrostat, and immediately the temperature and dew point inside the packaging material and the weight of the desiccant after the test were measured. In addition, when the weight of the desiccant after the test exceeds 130% of the weight of the enclosed desiccant, the retention time in the thermo-hygrostat is shortened, or the amount of the desiccant is increased, etc., and measurement is performed again. Also, from the temperature and dew point measured before the start of the test and after the end of the test, the absolute humidity (g / m 3 ) before the start of the test and after the end of the test was calculated. Specifically, the temperature and dew point were input into the VAISALA Humidity Calculator to obtain the absolute humidity. The measurement was carried out 3 times for each sample, and the water vapor permeability was calculated using the following formula, and the average value was taken as the water vapor permeability of the packaging material. Change in the amount of water vapor in the internal gas (g) = {Absolute humidity at the end of the test (g / m 3 ) - Absolute humidity at the start of the test (g / m 3 )} × Internal volume of the packaging material (m 3 ) Water vapor permeability (g / (m 2 × 24 hr)) = {Weight of the desiccant after the test (g) - Weight of the enclosed desiccant (g) + Change in the amount of water vapor in the internal gas (g)} / {External surface area of the packaging material (m 2 ) × {Retention time in the thermo-hygrostat (hr) / 24 (hr)}}

[0114] Measurement method C: For the core tube Figure 2 is a schematic diagram illustrating the method for measuring water vapor transmission. As shown in Figure 2, for the core tube, a film 13 that indicates the water vapor transmission rate was wrapped around the outer surface of the core tube 11, dry air with a dew point of -30°C dp was sealed inside the space between the film and the core tube, 800g of a desiccant 16 of JIS Z 0701 (Desiccants for Packaging) Grade 1A or equivalent quality was placed inside, and the joint 15 between the film and the core tube was sealed with tape to form a glass cloth package 10. If 800g of desiccant could not be placed inside, the weight of the enclosed desiccant was measured so that it would be determined, and the amount of desiccant should be enclosed to be at least half the volume of the packaging material. Subsequently, the water vapor transmission rate of the packaging material was calculated in the same manner as in <Method for measuring the water vapor transmission rate of packaging material: Measurement Method B>. Then, based on the water vapor transmission rate of the film wrapped around the outer surface of the core tube and its surface area, the water vapor transmission rate of the core tube was determined using the following formula. Water vapor transmission rate of packaging material (g / m³) 2 (×24hr)) = {Water vapor transmission rate of film (g / (m³) 2 ×24hr)) × surface area of ​​film (m 2 ) + Water vapor permeability of the core tube (g / (m) 2 ×24hr)) ×Outer diameter side surface area of ​​core tube (m²) 2 )} / {Surface area of ​​the film (m 2 ) + Outer diameter side surface area of ​​core tube (m 2 )}

[0115] <Rate of change of dielectric loss tangent (Df) of glass cloth> The rate of change in the dielectric loss tangent (Df) of glass cloth is the dielectric loss tangent (Df0) at the start of storage, compared to the dielectric loss tangent (Df0) after X days of storage. x ) was obtained using the following formula. Df change rate (%) = Df x / Df0× 100

[0116] The dielectric loss tangent of glass cloth at 10 GHz indicates that the smaller the rate of change (increase) over a long period, the greater the effect of maintaining the storage environment of the glass cloth. The rate of change of glass cloth over time is evaluated by the above formula, and the rate of change of the dielectric loss tangent of glass cloth 365 days after the start of storage is preferably 180% or less, more preferably 160% or less, even more preferably 140% or less, even more preferably 120% or less, and particularly preferably 110% or less. Furthermore, the rate of change of the dielectric loss tangent of glass cloth after 30 days is preferably 120% or less, more preferably 115% or less, even more preferably 110% or less, and particularly preferably 105% or less. If the change in dielectric loss tangent is within the above range (120% or less after 30 days and 180% or less after 365 days), it is considered that the effect of controlling the storage environment of the glass cloth has been obtained. The start date of storage is not particularly limited, but it is the date on which a person skilled in the art begins to store glass cloth in a certain environment for a certain period of time. For example, the storage start date is defined as the day the glass cloth is packaged in film and / or box-shaped packaging material after the surface treatment of the glass cloth is completed, and the storage period is defined as the time until the packaged glass cloth is opened at the customer's process.

[0117] <Percentage change in dew point> The percentage change in the dew point inside a package containing a desiccant was calculated using the following formula. Dew point change rate = (Dew point of the storage environment after 365 days of storage (°Cdp) - Initial dew point of the storage environment (°Cdp)) / (Average dew point of the external environment of the packaging material (°Cdp) - Dew point of the storage environment after 365 days of storage (°Cdp)) However, if the average dew point of the external environment of the packaging material was equal to the dew point of the storage environment after 365 days of storage, it was deemed unacceptable (NG).

[0118] <Method for measuring the surface area of ​​packaging materials> The surface area of ​​the packaging material was determined by measuring the shape of the packaged product after packaging. As shown in Figure 1(1c), when the glass cloth is sealed from the external environment by a film and a core tube, the surface area of ​​the packaging material was determined by measuring the surface area of ​​the film-like packaging material and the outer diameter side surface area of ​​the core tube, respectively.

[0119] Desiccant and film Types of desiccant • Desiccant A: Ablio® AW (Type A silica gel), manufactured by Toyota Chemical Corporation. • Desiccant B: RP agent manufactured by Mitsubishi Gas Chemical Company, Inc. (MGC) (calcined diatomaceous earth and calcium oxide)

[0120] <Types of film> [Table 1]

[0121] Manufacturing of glass cloth <Manufacturing of Q1035 (raw fabric cloth)> Using glass yarn with an SiO2 composition content greater than 99.9% by mass, a cloth was woven in an air-jet loom at a weaving density of 66 warp threads / 25 mm and 68 weft threads / 25 mm. The cloth width was woven to 1300 mm. For the warp threads, silica glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used. Similarly, silica glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used for the weft threads.

[0122] <L1035 (raw fabric cloth) cloth manufacturing> Using glass yarn with an SiO2 composition of 53% by mass and a B2O3 composition of 23% by mass, a cloth was woven in an air-jet loom at a weaving density of 66 warp threads / 25 mm and 68 weft threads / 25 mm. The cloth width was woven to 1300 mm. Glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used as the warp thread. Glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used as the weft thread.

[0123] Examples and Comparative Examples <Example A1> The obtained Q1035 raw cloth was de-oiled by heating it in a heating furnace at 600°C for 60 seconds (heating de-oiling process). Subsequently, a treatment solution was prepared by dispersing 0.15% by mass of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow-Toray) and 0.15% by mass of 5-hexenyltrimethoxysilane (silane coupling agent B); Z6161 (manufactured by Dow-Toray) in pure water adjusted to pH=3 with acetic acid. The cloth was immersed in the treatment solution at a line tension of 200N and a line speed of 30m / min (surface treatment agent coating process), squeezed with an NBR rubber roll at a pressure of 0.3MPa, and then heated and dried at 130°C for 60 seconds to fix the silane coupling agents (fixing process). The dried cloth was sprayed at a rate of 2.0kg / cm². 2 After high-pressure fiber separation, the glass cloth was dried at 130°C for 1 minute (drying process) and then wound up to obtain a roll of glass cloth. This glass cloth was stored in a storage room maintained at a temperature of 23°C and a dew point of -30°Cdp by circulating dry air at -30°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0124] <Example A2> The roll of glass cloth obtained in Example A1 was subjected to film A (thickness 99 μm, water vapor transmission rate 0.1 g / m²) in an environment of 23°C. 2 The glass cloth was packaged in a bag with a dew point of 24 hours (×24hr) and a desiccant A (800g) was sealed inside. Furthermore, dry air with a dew point of -20°Cdp was sealed inside to bring the dew point to -20°Cdp, and the opening was heat-sealed to obtain the packaged glass cloth. Subsequently, the packaged glass cloth was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0125] <Example A3> Except for heating the obtained Q1035 raw cloth at 1000°C for 60 seconds to remove oil, a roll of glass cloth was obtained by the same processing as in Example A1. This glass cloth was then placed in a box-shaped packaging material (water vapor transmission rate 0.0 g / m²) under conditions of 23°C and a dew point of 12°Cdp. 2The glass cloth was placed in a container (×24hr). Subsequently, a desiccant A (800g) was sealed inside the packaging, and the container was stored in a sealed container. After 30 days and 365 days, the glass cloth was removed and evaluated.

[0126] <Example A4> A roll of glass cloth was obtained in the same manner as in Example A1, except that the obtained Q1035 raw cloth was heated at 370°C for 72 hours in a batch-type heating furnace to perform a heat de-oiling process, and a treatment solution was prepared and used in which 0.30% by mass of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow-Toray) was dispersed. This glass cloth was then subjected to a film A (thickness 99 μm, water vapor transmission rate 0.1 g / m²) under conditions of 23°C and a dew point of 12°C dp. 2 The glass cloth was packaged in a bag with a moisture absorption agent B (800g) sealed inside. The opening was then heat-sealed to obtain the packaged glass cloth. The packaged glass cloth was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0127] <Example A5> The rolled glass cloth obtained in Example A1 was stored in a storage room maintained at a temperature of 25°C and a dew point of 2°C dp using a dehumidifier. The glass cloth was removed and evaluated after 30 days and 365 days.

[0128] <Example A6> The rolled glass cloth obtained in Example A1 was stored in a storage room maintained at a temperature of 25°C and a dew point of 8°C dp using a dehumidifier. The glass cloth was removed and evaluated after 30 days and 365 days.

[0129] <Example A7> The roll of glass cloth obtained in Example A1 was subjected to a box-shaped packaging material (water vapor transmission rate 0.0 g / m²) under conditions of 30°C and a dew point of 24°C dp. 2 Place in a 24hr container and use a vacuum pump to remove the contents 10° 3After reducing the pressure to Pa, it was sealed and stored. At this time (10 3 The dew point inside the box-shaped packaging material at Pa was -32°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0130] <Example A8> The roll of glass cloth obtained in Example A1 was subjected to film B (thickness 116 μm, water vapor transmission rate 0.2 g / m²) under conditions of 23°C and a dew point of 12°C dp. 2 The glass cloth was packaged in a bag with a dew point of 24 hours (×24hr) and a desiccant A (800g) was sealed inside. Furthermore, dry air with a dew point of -20°Cdp was sealed inside to bring the dew point to -20°Cdp, and the opening was heat-sealed to obtain the packaged glass cloth. Subsequently, the packaged glass cloth was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0131] <Example A9> The roll of glass cloth obtained in Example A1 was subjected to film C (thickness 78 μm, moisture permeability 6.6 g / m²) under conditions of temperature 23°C and dew point 12°C dp. 2 The glass cloth was packaged in a bag with a moisture content of 24 hours (×24hr) and a desiccant A (8000g) was sealed inside. The opening was then heat-sealed to obtain the packaged glass cloth. The packaged glass cloth was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0132] <Example A10> The rolled glass cloth obtained in Example A1 was stored in a storage room maintained at a temperature of 45°C and a dew point of -2°Cdp by circulating dry air at -2°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0133] <Example A11> The obtained Q1035 raw cloth was heated in a heating furnace at 600°C for 60 seconds to remove oil (heating de-oiling process), and then wound up to obtain a roll of glass cloth. This glass cloth was stored in a storage room maintained at a temperature of 23°C and a dew point of -30°Cdp by circulating dry air at -30°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0134] <Comparative Example A1> The rolled glass cloth obtained in Example A1 was stored in a storage room maintained at a temperature of 30°C and a dew point of 24°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0135] <Reference example A> Roll-shaped glass cloth was obtained in the same manner as in Example A1, except that the obtained L1035 raw cloth was heated at 370°C for 72 hours in a batch-type heating furnace to perform a heat de-oiling process. This glass cloth was stored in a storage room maintained at a temperature of 30°C and a dew point of 24°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0136] <Comparative example A2> The rolled glass cloth obtained in Example A3 was stored in a storage room maintained at a temperature of 30°C and a dew point of 24°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0137] <Comparative example A3> The rolled glass cloth obtained in Example A4 was stored in a storage room maintained at a temperature of 30°C and a dew point of 24°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0138] <Comparative example A4> The rolled glass cloth obtained in Example A1 was stored in a storage room maintained at a temperature of 40°C and a dew point of 38°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0139] <Comparative Example A5> The roll of glass cloth obtained in Example A1 was subjected to film D (thickness 45 μm, water vapor transmission rate 11 g / m²) under conditions of 23°C and a dew point of 12°C dp. 2 The glass cloth was packaged in a bag with a moisture content of 24 hours (×24hr) and a desiccant A (8000g) was sealed inside. The opening was then heat-sealed to obtain the packaged glass cloth. The packaged glass cloth was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0140] <Comparative example A6> The rolled glass cloth obtained in Example A11 was stored in a storage room maintained at a temperature of 30°C and a dew point of 24°Cdp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0141] The manufacturing conditions and evaluation results for Examples A1-A11, Comparative Examples A1-A6, and Reference Example A are shown in the table below.

[0142] [Table 2]

[0143] [Table 3]

[0144] In Example A1, the dielectric loss tangent of the glass cloth did not change after long-term storage (after 30 and 365 days), whereas in Comparative Example A1, the dielectric loss tangent of the glass cloth increased significantly. On the other hand, in Reference Example A, where the dielectric loss tangent of the glass cloth was higher than 0.00200, no increase in the dielectric loss tangent was observed even under the same storage conditions as in Comparative Example A1. In Comparative Example A5, the high water vapor permeability of the bag packaging the glass cloth resulted in a large inflow of moisture, making it difficult to sufficiently lower the internal dew point even with the use of a desiccant.

[0145] Desiccant and packaging materials Types of desiccant • Desiccant A: Ablio® AW (Type A silica gel), manufactured by Toyota Chemical Corporation. • Desiccant B: RP agent manufactured by Mitsubishi Gas Chemical Company, Inc. (MGC) (calcined diatomaceous earth and calcium oxide)

[0146] <Types of packaging materials> [Table 4]

[0147] Manufacturing of glass cloth <Manufacturing of Q1035 (raw fabric cloth)> Using glass yarn with an SiO2 composition content greater than 99.9% by mass, a cloth was woven in an air-jet loom at a weaving density of 66 warp threads / 25 mm and 68 weft threads / 25 mm. The cloth width was woven to 1300 mm. For the warp threads, silica glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used. Similarly, silica glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used for the weft threads.

[0148] <L1035 (raw fabric cloth) cloth manufacturing> Using glass yarn with an SiO2 composition of 53% by mass and a B2O3 composition of 23% by mass, a cloth was woven in an air-jet loom at a weaving density of 66 warp threads / 25 mm and 68 weft threads / 25 mm. The cloth width was woven to 1300 mm. Glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used as the warp thread. Glass yarn with an average filament diameter of 5.0 μm, 100 filaments, and 1.0 Z twist was used as the weft thread.

[0149] Examples and Comparative Examples <Example B1> The obtained Q1035 raw cloth was de-oiled by heating it in a heating furnace at 600°C for 60 seconds (heating de-oiling process). Subsequently, a treatment solution was prepared by dispersing 0.15% by mass of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow-Toray) and 0.15% by mass of 5-hexenyltrimethoxysilane (silane coupling agent B); Z6161 (manufactured by Dow-Toray) in pure water adjusted to pH=3 with acetic acid. The cloth was immersed in the treatment solution at a line tension of 200N and a line speed of 30m / min (surface treatment agent coating process), squeezed with an NBR rubber roll at a pressure of 0.3MPa, and then heated and dried at 130°C for 60 seconds to fix the silane coupling agents (fixing process). The dried cloth was sprayed at a rate of 2.0kg / cm². 2 After high-pressure fiber separation using the specified pressure, the material was dried at 130°C for 1 minute (drying process), and then wound onto a core tube having a hollow section to obtain a roll of glass cloth.

[0150] This glass cloth was subjected to a process in an environment of 23°C using packaging material A (aluminum laminate film, thickness 99 μm, water vapor transmission rate 0.1 g / m²). 2 The glass cloth packaging was sealed with a desiccant A (800g) at 24hr. Dry air with a dew point of -20°Cdp was then sealed inside to maintain a dew point of -20°Cdp, and the opening was heat-sealed to obtain a glass cloth package. Subsequently, the glass cloth package was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0151] <Example B2> Except for heating the obtained Q1035 raw cloth at 1000°C for 60 seconds to remove oil, a roll of glass cloth was obtained by the same processing as in Example B1. This glass cloth was packaged in a stainless steel box with a water vapor transmission rate of 0.0 g / m² under conditions of 23°C and a dew point of 12°Cdp. 2It was placed in (×24 hr). Subsequently, desiccant A (800 g) was enclosed inside the packaging material and sealed to form a glass cloth package. Thereafter, the glass cloth package was moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0152] 〈Example B3〉 The obtained Q1035 viable cloth was heated at 370°C for 72 hours using a batch-type heating furnace as a heat deoiling process, and a treatment liquid in which 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow Corning Toray Co., Ltd.) was dispersed at 0.30 mass% was prepared and used. A roll-shaped glass cloth was obtained in the same manner as in Example B1 except for this point and used. This glass cloth was packaged with Packaging Material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m 2 ×24 hr)) under an environment with a temperature of 23°C and a dew point of 12°C dp, and desiccant B (800 g) was enclosed inside. Furthermore, the opening was heat-sealed to obtain a glass cloth package. Thereafter, the glass cloth package was moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0153] 〈Example B4〉 The roll-shaped glass cloth obtained in Example B1 was packaged with Packaging Material B (ceramic vapor deposition film, thickness 116 μm, water vapor permeability 0.2 g / (m 2 ×24 hr)) under an environment with a temperature of 23°C, and desiccant A (800 g) was enclosed inside. Furthermore, dry air with a dew point of -20°C dp was enclosed inside to set the dew point to -20°C dp, and the opening was heat-sealed to obtain a glass cloth package. Thereafter, the glass cloth package was moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0154] 〈Example B5〉 The roll of glass cloth obtained in Example B1 was subjected to packaging material C (ceramic vapor-deposited film, thickness 115 μm, water vapor transmission rate 1.5 g / m²) under conditions of temperature 23°C and dew point 12°C dp. 2 The glass cloth packaging was prepared by packaging it at 24 hours, sealing it with 8000g of desiccant A, and heat-sealing the opening. The glass cloth packaging was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0155] <Example B6> The roll of glass cloth obtained in Example B1 was subjected to a process in an environment of 23°C and a dew point of 12°C dp using packaging material D (ceramic vapor-deposited film, thickness 78 μm, water vapor transmission rate 6.6 g / (m²)). 2 The glass cloth packaging was sealed with a desiccant A (8000g) and then heat-sealed at the opening to obtain a glass cloth package. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0156] <Example B7> The glass cloth obtained in roll form in Example B1 was packaged in a stainless steel box with a water vapor transmission rate of 0.0 g / m² under conditions of 30°C and a dew point of 24°C dp. 2 Place in a 24hr container and use a vacuum pump to remove the contents 10° 3 After reducing the pressure to Pa, it was sealed and packaged in glass cloth. At this time (10 3 The dew point inside the glass cloth packaging at Pa) was -32°Cdp. Subsequently, the glass cloth packaging was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0157] <Example B8> The obtained Q1035 raw cloth was heated in a heating furnace at 600°C for 60 seconds to remove oil (heating and oil removal process), and then wound onto a core tube having a hollow section to obtain a roll of glass cloth. This glass cloth was then packaged in packaging material A (aluminum laminate film, thickness 99 μm, water vapor transmission rate 0.1 g / m²) in an environment of 23°C. 2 The glass cloth packaging was sealed with a desiccant A (800g) at 24hr. Dry air with a dew point of -20°Cdp was then sealed inside to maintain a dew point of -20°Cdp, and the opening was heat-sealed to obtain a glass cloth package. Subsequently, the glass cloth package was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0158] <Comparative Example B1> The roll of glass cloth obtained in Example B1 was subjected to packaging under conditions of 23°C and a dew point of 12°Cdp, with packaging material E (polyethylene film, 45 μm thickness, moisture permeability 11 g / (m²)). 2 The glass cloth packaging was sealed with a desiccant A (8000g) and then heat-sealed at the opening to obtain a glass cloth package. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0159] <Reference example B> A roll of glass cloth was obtained in the same manner as in Example B1, except that the obtained L1035 raw cloth was heated at 370°C for 72 hours in a batch-type heating furnace to perform a heat de-oiling process. This glass cloth was then packaged in an environment with a temperature of 23°C and a dew point of 12°Cdp using packaging material E (polyethylene film, thickness 45 μm, moisture permeability 11 g / (m²)). 2 The glass cloth packaging was sealed with a desiccant A (8000g) and then heat-sealed at the opening to obtain a glass cloth package. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0160] <Comparative example B2> The rolled glass cloth obtained in Example B2 was subjected to packaging in a corrugated cardboard box with a water vapor transmission rate of 50 g / m² under conditions of 23°C and a dew point of 12°C dp. 2 The glass cloth was placed in a 24hr container. Subsequently, 8000g of desiccant A was sealed inside the packaging, and the container was sealed to form a glass cloth package. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0161] <Comparative Example B3> The roll of glass cloth obtained in Example B3 was subjected to packaging in a corrugated cardboard box with a water vapor transmission rate of 50 g / m² under conditions of 23°C and a dew point of 12°C dp. 2 The glass cloth was placed in a container (×24hr), sealed, and packaged in glass cloth. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0162] <Comparative example B4> The roll of glass cloth obtained in Example B8 was subjected to packaging under conditions of 23°C and a dew point of 12°Cdp, with packaging material E (polyethylene film, 45 μm thickness, moisture permeability 11 g / (m²)). 2 The glass cloth packaging was obtained by packaging the glass cloth at 24 hours and then heat-sealing the opening. The glass cloth packaging was then moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0163] The manufacturing conditions and evaluation results for Examples B1-B8, Comparative Examples B1-B4, and Reference Example B are shown in the table below.

[0164] [Table 5]

[0165] [Table 6]

[0166] In Example B1, the dielectric loss tangent of the glass cloth did not change after long-term storage (after 30 days and 365 days), while in Comparative Example B1, the dielectric loss tangent of the glass cloth increased significantly. In Comparative Example B1, due to the high water vapor permeability of the bag for packaging the glass cloth, the amount of water inflow increased, and it was difficult to sufficiently lower the internal dew point even with a desiccant. On the other hand, in Reference Example B where the dielectric loss tangent of the glass cloth was higher than 0.00200, no increase in the dielectric loss tangent was observed even in the same storage environment as Comparative Example B1.

[0167] 〈Type of core tube〉

Table 7

[0168] 〈Example B9〉 The roll-shaped glass cloth obtained in Example B1 was packaged at a temperature of 23°C with Packaging Material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m 2 ×24 hr)) which is wider than the width of the roll, and Desiccant A (800 g) was enclosed inside. With dry air at a dew point of -20°C dp enclosed inside Packaging Material A to set the dew point to -20°C dp, the opening was heat-sealed by thermocompression bonding. The excess packaging material on one side was pushed into the hollow part of the core tube, and a glass cloth package having a recess extending from one end of the core tube to the inside of the hollow part was obtained. The surface area of Packaging Material A was 3.5 m 2 , and the volume occupied by the space inside the package in the volume of the hollow part of the core tube was 2%. Then, the glass cloth package was moved to an external environment at a temperature of 30°C and a dew point of 24°C dp and stored. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0169] 〈Example B10〉 The roll-shaped glass cloth obtained in Example B1 was packaged at a temperature of 23°C with Packaging Material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m 2The glass cloth was packaged at 24 hours (×24hr) and a desiccant A (800g) was sealed inside. A tubular packaging material A was inserted into the core tube from which the roll of glass cloth was wound, so as to follow the inner wall of the tube. Dry air with a dew point of -20°Cdp was sealed inside the packaging material A covering the outer surface of the roll to maintain a dew point of -20°Cdp. The packaging material A covering the outer surface of the roll and the tubular packaging material A penetrating the inner diameter of the core tube were then heat-pressed together to seal the opening, obtaining an annular glass cloth package with the external environment penetrating the hollow part. At this time, the surface area of ​​packaging material A was 3.0m². 2 The volume occupied by the interior of the packaging was 5% of the volume of the hollow part of the core tube. Subsequently, the glass cloth packaging was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0170] <Example B11> The resulting glass cloth has a water vapor permeability of 0.1 g / m². 2 A roll of glass cloth was obtained in the same manner as in Example B1, except that it was wound onto an FRP core tube H (24 hours of drying). This roll of glass cloth was subjected to a temperature of 23°C and packaging material A (aluminum laminate film, 99 μm thick, water vapor transmission rate 0.1 g / m²) 2 The product was packaged at 24 hours (×24hr) and a desiccant A (800g) was sealed inside. Dry air with a dew point of -20°Cdp was sealed inside packaging material A to maintain a dew point of -20°Cdp. The film at the opening was then sealed with moisture-proof airtight tape on the exposed outer surface of the core tube to obtain a glass cloth package. At this time, the surface area of ​​packaging material A was 2.0m². 2 Therefore, the outer diameter surface area of ​​the core tube is 1.0 m². 2 The volume occupied by the interior of the packaging was 0% of the volume of the hollow part of the core tube. Subsequently, the glass cloth packaging was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0171] <Example B12> The resulting glass cloth has a water vapor permeability of 1.0 g / m². 2A roll of glass cloth was obtained in the same manner as in Example B1, except that it was wound onto an FRP core tube I (24 hours of drying). This roll of glass cloth was subjected to a temperature of 23°C and packaging material A (aluminum laminate film, 99 μm thick, water vapor transmission rate 0.1 g / m²) 2 The product was packaged at 24 hours (×24hr) and a desiccant A (1200g) was sealed inside. Dry air with a dew point of -20°Cdp was sealed inside packaging material A to maintain a dew point of -20°Cdp. The film at the opening was then sealed with moisture-proof airtight tape on the exposed outer surface of the core tube to obtain a glass cloth package. At this time, the surface area of ​​packaging material A was 2.0m². 2 Therefore, the outer diameter surface area of ​​the core tube is 1.0 m². 2 The volume occupied by the interior of the packaging was 0% of the volume of the hollow part of the core tube. Subsequently, the glass cloth packaging was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0172] <Comparative Example B5> The resulting glass cloth has a water vapor transmission rate of 9.6 g / m². 2 A roll of glass cloth was obtained in the same manner as in Example B1, except that it was wound onto a paper core tube J (×24hr). This roll of glass cloth was subjected to packaging under conditions of 23°C and a dew point of 12°Cdp using packaging material E (polyethylene film, 45 μm thick, moisture permeability 11 g / (m²)). 2 The product was packaged using a 24hr desiccant solution and 8000g of desiccant A was sealed inside. The film at the opening was sealed to the core tube with moisture-proof airtight tape to obtain a glass cloth package. At this time, the surface area of ​​the packaging material E was 1.8m². 2 Therefore, the outer diameter surface area of ​​the core tube is 0.8 m². 2 The volume occupied by the interior of the packaging was 0% of the volume of the hollow part of the core tube. Subsequently, the glass cloth packaging was moved to an external environment with a temperature of 30°C and a dew point of 24°Cdp and stored. The glass cloth was removed and evaluated after 30 days and 365 days.

[0173] The manufacturing conditions and evaluation results for Examples B9 to B12 and Comparative Example B5 are shown in the table below.

[0174] [Table 8]

[0175] In Examples B1 to B12, the dielectric loss tangent of the glass cloth remained unchanged after long-term storage (30 days and 365 days), whereas in Comparative Example B5, the dielectric loss tangent of the glass cloth increased significantly. [Explanation of Symbols]

[0176] 10 Glass cloth packaging 11 Core tube 12 Glass cloth 13 Film 13a Outer film 13b Inner film 14 recess 15 Joint 16. Desiccant

Claims

1. This is a method for storing glass cloth. The glass cloth is composed of glass threads containing multiple filaments as warp and weft threads, and the silicon (Si) content in the glass threads is 95.0% to 100% by mass in terms of silicon dioxide (SiO₂). The dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less, and the glass cloth is in a roll state. The method includes storing the glass cloth in an atmosphere where the mean dew point at the atmospheric pressure of the storage environment is 10°C dp or less and the mean temperature is 100°C or less. A method for storing glass cloth in which the atmosphere is reduced to below atmospheric pressure.

2. A method for storing glass cloth, The glass cloth is composed of glass threads containing multiple filaments as warp and weft threads, and the silicon (Si) content in the glass threads is 95.0% to 100% by mass in terms of silicon dioxide (SiO₂). The dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less, and the glass cloth is in a roll state. The glass cloth is stored as a package in which it is wrapped in a film-like packaging material, and the thickness of the film-like packaging material is 50 μm or more. The method includes storing the glass cloth in an atmosphere where the mean dew point at the atmospheric pressure of the storage environment is 10°C dp or less and the mean temperature is 100°C or less. How to store fiberglass cloth.

3. The method according to claim 1 or 2, wherein the glass cloth has a surface treatment agent containing a silane coupling agent on its surface.

4. The surface treatment agent is defined by the following formula (1): X (R) ３－ｎ Yes ｎ ・・・(1) (In formula (1), X is an organic functional group having at least one of an amino group and a radically reactive unsaturated double bond group, Y is independently an alkoxy group, n is an integer between 1 and 3, and R is independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.) The method according to claim 3, comprising a silane coupling agent indicated by [formula].

5. The method according to claim 4, wherein the surface treatment agent comprises two or more silane coupling agents in which X is different in formula (1).

6. The method according to claim 3, wherein the surface treatment agent comprises two or more silane coupling agents with different molecular weights.

7. The method according to claim 3, further comprising the steps of surface-treating the glass cloth with a surface treatment agent containing a silane coupling agent before storage, and opening the fibers of the surface-treated glass cloth.

8. The method according to claim 1 or 2, wherein the dielectric loss tangent of the glass cloth at 10 GHz is 0.00051 or more and 0.00200 or less.

9. The method according to claim 1 or 2, wherein the density of the warp and / or weft threads of the glass cloth is in the range of 66 to 120 threads / inch (= 66 to 120 threads / 25 mm).

10. The method according to claim 1 or 2, further comprising the step of heating the glass cloth to a temperature of 600°C or higher while transporting it by roll-to-roll before storage.

11. The method according to claim 1, wherein the glass cloth is stored as a package, which is wrapped in a box and / or a film-like packaging material.

12. The method according to claim 11, wherein the glass cloth is stored as a package in which it is wrapped in a film-like packaging material, and the thickness of the film-like packaging material is 50 μm or more.

13. The method according to claim 2 or 11, wherein the glass cloth is stored as a packaged body in which it is wrapped in a film-like packaging material, and the film-like packaging material is an aluminum laminate film.

14. The method according to claim 2 or 11, wherein the glass cloth is stored as a packaged body wrapped in a film-like packaging material in a roll state in which it is wound around a hollow columnar core tube, and the film-like packaging material has recesses extending into the hollow portion from one or both ends of the core tube, or is an annular ring that penetrates the hollow portion of the core tube.

15. The method according to claim 14, wherein the proportion of the volume of the hollow portion of the core tube that is occupied by the space inside the film-like packaging material is 50% or less of the volume of the hollow portion of the core tube.

16. The method according to claim 14, wherein the film-like packaging material is an annular ring that penetrates the hollow portion of the core tube.

17. The method according to claim 14, wherein the packaging is configured such that the glass cloth is sealed from the external environment by the film-like packaging material and the core tube.

18. The water vapor transmission rate of the aforementioned core tube, measured under conditions of 40°C and 90% Rh, was 8 g / (m³). ２ The method according to claim 14, wherein the length is less than or equal to 24 hours.

19. The aforementioned packaging material has a water vapor transmission rate of 8 g / m³ at a measurement temperature of 40°C and a measurement humidity of 90% Rh. ２ The method according to claim 2 or 11, wherein the frequency is less than or equal to 24 hours.

20. The method according to claim 2 or 11, wherein the packaging is configured to dehumidify so as to maintain the mean dew point inside it at 10°C dp or less.

21. The method according to claim 1 or 2, further comprising storing the items at a mean dew point of -21°C dp or lower under the atmospheric pressure of the storage environment.

22. The method according to claim 2 or 11, wherein the packaging contains a desiccant.

23. The amount of the aforementioned desiccant enclosed is given by the following formula (2): WVTR [g / (m)] ２ ×24hr)] × package surface area [m ２ ] / Amount of desiccant enclosed [g] ≤ 0.0030 ... (2) The method according to claim 22, satisfying the following: (In formula (2), WVTR is the water vapor transmission rate of the packaging material at a measurement temperature of 40°C and a measurement humidity of 90% Rh.)

24. The method according to claim 22, wherein the desiccant is at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccants, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate.

25. The method according to claim 22, wherein the desiccant is a sheet-type desiccant.

26. The method according to claim 1 or 2, wherein the atmosphere is dry air with a mean dew point of 10°C dp or less, or a gas containing at least one selected from the group consisting of nitrogen, argon, and oxygen, with a mean dew point of 10°C dp or less.

27. The method according to claim 2, wherein the atmosphere is reduced to below atmospheric pressure.

28. The method according to claim 1 or 2, wherein the glass cloth is stored in a storage room with controlled dew point and temperature.

29. The basis weight (mass) of the aforementioned glass cloth is 8 to 25 g / m². ２ The method according to claim 1 or 2, which is within the range of claim 1 or 2.

30. A glass cloth package comprising a packaging material and glass cloth housed inside the packaging material, The aforementioned glass cloth is composed of glass threads containing multiple filaments as warp and weft threads, The silicon (Si) content in the glass yarn is 95.0% to 100% by mass in terms of silicon dioxide (SiO₂). The dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less. The aforementioned packaging material is sealed, The glass cloth is in a rolled state, The water vapor transmission rate of the aforementioned packaging material, measured under conditions of 40°C and 90% Rh, was 8 g / (m³). ２ The dew point inside the packaging material is 10°C dp or less (×24hr), A glass cloth packaging in which the inside of the packaging material is reduced to below atmospheric pressure.

31. A glass cloth package comprising a packaging material and glass cloth housed inside the packaging material, The aforementioned glass cloth is composed of glass threads containing multiple filaments as warp and weft threads, The silicon (Si) content in the glass yarn is 95.0% to 100% by mass in terms of silicon dioxide (SiO₂). The dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less. The aforementioned packaging material is sealed, The glass cloth is in a rolled state, The water vapor transmission rate of the aforementioned packaging material, measured under conditions of 40°C and 90% Rh, is 8 g / (m² × 24hr) or less, and the dew point inside the aforementioned packaging material is 10°C dp or less. A glass cloth packaging body in which the packaging material is a film and the thickness of the film is 50 μm or more.

32. The glass cloth packaging according to claim 30, wherein the packaging material is a box and / or film.

33. The glass cloth packaging body according to claim 30, wherein the packaging material is a film and the thickness of the film is 50 μm or more.

34. The glass cloth packaging body according to claim 30 or 31, wherein the packaging material is a film, and the film is an aluminum laminate film.

35. The glass cloth packaging according to claim 30 or 31, wherein the glass cloth is packaged in a film in a roll wound around a hollow columnar core tube, and the film has a recess extending into the hollow portion from one or both ends of the core tube, or is an annular ring penetrating the hollow portion of the core tube.

36. The glass cloth packaging according to claim 35, wherein the proportion of the volume of the hollow portion of the core tube that is occupied by the space inside the film is 50% or less of the volume of the hollow portion of the core tube.

37. The glass cloth packaging body according to claim 35, wherein the film is an annular ring that penetrates the hollow portion of the core tube.

38. The glass cloth packaging according to claim 35, wherein the packaging is configured such that the glass cloth is sealed from the external environment by the film and the core tube.

39. The water vapor permeability of the core tube measured under the conditions of 40 °C and 90% Rh is 8 g / (m ２ ×24 hr) or less, the glass cloth packaging body according to claim 35.

40. The glass cloth packaging according to claim 30 or 31, wherein the dew point inside the packaging material is -21°C dp or lower.

41. The glass cloth packaging according to claim 30 or 31, wherein a desiccant is sealed inside the packaging material.

42. The amount of the aforementioned desiccant enclosed is given by the following formula (2): WVTR [g / (m)] ２ ×24hr)] × package surface area [m ２ ] / Amount of desiccant enclosed [g] ≤ 0.0030 ... (2) The glass cloth packaging according to claim 41, satisfying the following conditions: (In formula (2), WVTR is the water vapor transmission rate of the packaging material at a measurement temperature of 40°C and a measurement humidity of 90% Rh.)

43. The glass cloth packaging according to claim 41, wherein the desiccant is at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccants, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate.

44. The glass cloth packaging according to claim 41, wherein the desiccant is in the form of a sheet.

45. The glass cloth packaging according to claim 30 or 31, wherein the inside of the packaging material is filled with dry air having a dew point of 10°C dp or less, or with a gas having a dew point of 10°C dp or less and containing at least one selected from the group consisting of nitrogen, argon, and oxygen.

46. The glass cloth packaging according to claim 31, wherein the pressure inside the packaging material is less than atmospheric pressure.

47. The glass cloth packaging according to claim 30 or 31, wherein the glass cloth is treated with a surface treatment agent containing a silane coupling agent.

48. The surface treatment agent is defined by the following formula (1): X (R) ３－ｎ Yes ｎ ・・・(1) (In formula (1), X is an organic functional group having at least one of an amino group and a radically reactive unsaturated double bond group, Y is independently an alkoxy group, n is an integer between 1 and 3, and R is independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.) The glass cloth packaging according to claim 47, comprising the silane coupling agent indicated by [the specified symbol].

49. The glass cloth packaging according to claim 48, wherein the surface treatment agent comprises two or more silane coupling agents in which X is different in formula (1).

50. The glass cloth packaging according to claim 47, wherein the surface treatment agent comprises two or more silane coupling agents with different molecular weights.

51. The glass cloth packaging according to claim 30 or 31, wherein the dielectric loss tangent of the glass cloth at 10 GHz is 0.00051 or more and 0.00200 or less.

52. The glass cloth packaging according to claim 30 or 31, wherein the density of the warp and / or weft threads of the glass cloth is in the range of 66 to 120 threads / inch (= 66 to 120 threads / 25 mm).

53. The basis weight (mass) of the aforementioned glass cloth is 8 to 25 g / m². ２ A glass cloth packaging body according to claim 30 or 31, which is within the range of the specified range.

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