Storage method of glass cloth and glass cloth package

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

[0002] Currently, the performance of information terminals such as smartphones is improving, and high-speed communication, as typified by 5G communication, is advancing. In response to this background, for example, for printed wiring boards for high-speed communication, not only is there a demand for improved heat resistance, but also for further improvement in the dielectric properties of the insulating material (e.g., lowering the dielectric tangent). Similarly, there is a demand for improved dielectric properties of prepregs used as insulating materials for printed wiring boards, and glass yarns and glass cloths contained in the prepregs.

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

[0004] Patent Document 3 describes that the Si-OH group on the surface of quartz glass is highly active, and that in a high-temperature atmosphere, it takes in moisture through hydrogen bonding, and by cleaving the Si-O-Si bond, further Si-OH groups are generated (SiO2+H2O⇔Si-OH), and the generated Si-OH groups deteriorate the dielectric tangent of the glass cloth (paragraph 0006). Therefore, for the purpose of recombining the Si-OH groups to form Si-O-Si bonds and lowering the dielectric tangent of the glass cloth, it describes that when the quartz glass cloth is heat-treated, it is heated in a vacuum or gas with a dew point of 15°C or less under conditions where the maximum heating temperature is 100°C to 600°C, and the heating amount, expressed as heating temperature (°C) x heating time (h) above 100°C, is 450 (°C·h) or more (claim 1, etc.). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-127747 A [Patent Document 2] Patent Publication No. 2021-63320 [Patent Document 3] Patent No. 7269416 Summary of the Invention [Problem to be solved by the invention]

[0006] Patent Document 3 describes that the reaction SiO2+H2O⇔Si-OH does not have enough activation energy at temperatures below 100°C (paragraph 0025). Thus, it has been conventionally believed that water has no effect on the dielectric tangent of glass cloth in the temperature range below 100°C. In this regard, the present inventors have found for the first time that even if the dielectric tangent of glass cloth at the time of production is reduced by the means disclosed in Patent Documents 1 to 3, when the glass cloth is stored for a long period of time, the generation of silanol groups due to the above equilibrium reaction progresses even in an environment below 100°C, and the dielectric tangent of the glass cloth increases.

[0007] Therefore, an object of the present disclosure is to provide a method for storing glass cloth and a glass cloth package capable of maintaining the dielectric properties of the glass cloth having excellent dielectric properties. [Means for solving the problem]

[0008] Some embodiments of the present disclosure are exemplified in the following items [1] to

[57] . [1] A method for storing glass cloth, comprising the steps of: The glass cloth is configured with glass yarns including a plurality of filaments as warp yarns and weft yarns, and the dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less, The method for storing a glass cloth includes storing the glass cloth in an atmosphere having an average dew point of 18°C ​​dp or less and an average temperature of 100°C or less under the atmospheric pressure of the storage environment. [2] Item 2. The method according to item 1, wherein the silicon (Si) content in the glass yarn is 95.0% by mass to 100% by mass in terms of silicon dioxide (SiO2). [3] 3. The method according to item 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 represented 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 an unsaturated double bond group having radical reactivity, each Y is independently an alkoxy group, n is an integer of 1 to 3, and each 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 using a silane coupling agent represented by the formula: [5] 5. The method according to item 4, wherein the surface treatment agent contains two or more silane coupling agents having different X in the formula (1). [6] 6. The method according to any one of items 3 to 5, wherein the surface treatment agent contains two or more silane coupling agents having 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 the storage, and opening the surface-treated glass cloth. [8] 8. The method according to any one of items 1 to 7, wherein the glass cloth has a dielectric tangent at 10 GHz of 0.00051 or more and 0.00200 or less. [9] 9. The method according to any one of items 1 to 8, wherein the arrangement density of warp and / or weft 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 any one of items 1 to 9, further comprising a step of heating the glass cloth at a temperature of 600° C. or higher while transporting the glass cloth by roll-to-roll transport before the storage.

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

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

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

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

[15] Item 15. The method according to item 14, wherein the volume ratio of the space inside the film-like packaging material to the volume of the hollow part of the core tube is 50% or less of the volume of the hollow part of the core tube.

[16] 16. The method according to item 14 or 15, wherein the film-like packaging material is annular and penetrates the hollow portion of the core tube.

[17] 16. The method according to item 14 or 15, wherein the packaging body 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 permeability of the above core tube measured under conditions of 40℃ 90% Rh is 8g / (m 2 × 24 hr) or less.

[19] The above packaging material has a water vapor permeability of 8g / (m2) at a measurement temperature of 40°C and a measurement humidity of 90% Rh. 2 19. The method according to any one of items 11 to 18, wherein the time required for the measurement is 100 min. × 24 hr or less.

[20] 20. The method according to any one of items 11 to 19, wherein the packaging is configured to dehumidify so as to maintain an average dew point inside the packaging at or below 18°C ​​dp. [twenty one] 21. The method according to any one of items 1 to 20, comprising storing the storage environment having an average dew point under atmospheric pressure of 13°C dp or more and 18°C ​​dp or less. [twenty two] 21. The method according to any one of items 1 to 20, comprising storing the storage environment at an average dew point of −21° C. or less under atmospheric pressure. [twenty three] 20. The method according to any one of items 11 to 19, wherein the package contains a moisture absorbent. [twenty four] The amount of the moisture absorbent enclosed is expressed by the following formula (2): WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ] / amount of moisture absorbent enclosed [g]≦0.0030 (2) (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] 25. The method according to item 23 or 24, wherein the moisture absorbent 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] 26. The method according to any one of items 23 to 25, wherein the moisture absorbent is a sheet-shaped moisture absorbent.

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

[28] 28. The method according to any one of items 1 to 27, wherein the atmosphere is reduced to a pressure lower than atmospheric pressure.

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

[30] The weight of the glass cloth (mass of the glass cloth) is 8 to 25 g / m 2 30. The method according to any one of items 1 to 29, wherein the range is

[31] A glass cloth package comprising a packaging material and a glass cloth contained inside the packaging material, The glass cloth is formed of glass yarns including a plurality of filaments as warp and weft yarns, The dielectric tangent of the glass cloth at 10 GHz is 0.00200 or less, The packaging is sealed, The water vapor permeability of the above packaging material measured under conditions of 40℃ 90% Rh is 8g / (m 2 × 24hr) or less.

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

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

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

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

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

[37] Item 37. The glass cloth packaging according to item 35 or 36, wherein the film is annular and penetrates the hollow portion of the core tube.

[38] Item 37. 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 above core tube measured under conditions of 40℃ 90% Rh is 8g / (m 2 × 24 hr) or less.

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

[41] 40. The glass cloth packaging 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.

[42] 40. The glass cloth packaging according to any one of items 31 to 39, wherein the dew point inside the packaging material is −21° C. dp or lower.

[43] Item 43. The glass cloth packaging according to any one of items 31 to 42, wherein the glass cloth is in a roll state.

[44] 44. The glass cloth packaging according to any one of items 31 to 43, wherein a moisture absorbent is enclosed inside the packaging material.

[45] The amount of the moisture absorbent enclosed is expressed by the following formula (2): WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ] / amount of moisture absorbent enclosed [g]≦0.0030 (2) Item 45. The glass cloth packaging according to item 44, wherein (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] Item 46. The glass cloth packaging according to item 44 or 45, wherein the moisture absorbent 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] 47. The glass cloth packaging according to any one of items 44 to 46, wherein the moisture absorbent is in sheet form.

[48] Item 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 having a dew point of 18°C ​​dp or less, or a gas having a dew point of 18°C ​​dp or less and containing at least one gas selected from the group consisting of nitrogen, argon, and oxygen.

[49] Item 49. The glass cloth packaging according to any one of items 31 to 48, wherein the inside of the packaging material is at a pressure lower than atmospheric pressure.

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

[51] 51. The glass cloth packaging according to 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 surface treatment agent is represented 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 an unsaturated double bond group having radical reactivity, each Y is independently an alkoxy group, n is an integer of 1 to 3, and each R is independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.) Item 52. The glass cloth packaging according to item 51, comprising the silane coupling agent represented by the formula:

[53] Item 53. The glass cloth packaging according to item 52, wherein the surface treatment agent contains two or more silane coupling agents each having a different X in the formula (1).

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

[55] 55. The glass cloth packaging according to any one of items 31 to 54, wherein the glass cloth has a dielectric tangent at 10 GHz of 0.00051 or more and 0.00200 or less.

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

[57] The weight of the glass cloth (mass of the glass cloth) is 8 to 25 g / m 2 57. The glass cloth packaging according to any one of items 31 to 56, wherein the range is: Effect of the Invention

[0009] According to the present disclosure, it is possible to provide a method for storing glass cloth and a glass cloth package capable of maintaining the dielectric properties of the glass cloth having excellent dielectric properties. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing a cross section of a glass cloth packaging according to the present disclosure in the axial direction of a core tube. [Diagram 2] FIG. 2 is a schematic diagram for explaining a method for measuring the water vapor permeability of a core tube. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present disclosure (hereinafter, referred to as "the present embodiment") will be described. The present disclosure is not limited to the present embodiment, and various modifications are possible within the scope of the gist of the present disclosure. In this embodiment, the numerical range described using "~" includes the numerical values ​​before and after "~" as the lower limit and upper limit. In this embodiment, in a numerical range described in stages, the upper limit or lower limit described in a certain numerical range can be replaced with the upper limit or lower limit of another numerical range described in stages. In this embodiment, the upper limit or lower limit described in a certain numerical range can also be replaced with a value shown in the examples. In this embodiment, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes, as long as the function of the process is achieved.

[0012] How to store glass cloth The method for storing a glass cloth of the present disclosure relates to a method for storing a glass cloth that is composed of glass yarns containing a plurality of filaments as warps and wefts, and has a dielectric loss tangent of 0.00200 or less at 10 GHz. The method of the present disclosure includes storing the glass cloth in an atmosphere in which 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. In the past, it was thought that the reaction in which moisture cleaves Si-O-Si bonds to generate Si-OH groups was not activated in a temperature range below 100°C, so no special consideration was given to the method for storing the glass cloth, and the dielectric loss tangent sometimes increased over time. In this regard, by using the method of the present disclosure, the cleavage of Si-O-Si bonds due to moisture in the storage environment to generate Si-OH groups is suppressed, so that the increase 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 increase at all, but it is sufficient that the increase in the dielectric loss tangent is suppressed to a certain extent.

[0013] <Glass cloth> The glass cloth has a structure woven with glass yarns containing a plurality of glass filaments as warp and weft. Examples of the weaving structure of the glass cloth include plain weave, sash weave, satin weave, twill weave, etc. Among them, the plain weave structure is preferred.

[0014] The weft density of the warp and weft constituting the glass cloth is preferably 10 to 120 threads / inch (=10 to 120 threads / 25 mm) independently. The lower limit of the weft density 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 density is more preferably 110 threads / inch or less, or 100 threads / inch or less. If the weft density is within the above range, a glass cloth having a preferred thickness is easily obtained. The weft densities of the warp and weft may be different.

[0015] The weight of the glass cloth (mass of the glass cloth) is preferably 8 to 250 g / m2 , more preferably 8 to 100 g / m 2 , and more preferably 8 to 80 g / m 2 , and even more preferably 8 to 50 g / m 2 , and particularly preferably 8 to 25 g / m 2 , or 8 to 23.2 g / m 2 When the basis weight of the glass cloth is within the above range, a glass cloth having a preferable thickness is easily obtained.

[0016] The thickness of the glass cloth is preferably more than 0 and not more than 60 μm. The upper limit of the thickness of the glass cloth is more preferably not more than 55 μm, and further preferably not more than 50 μm. If the thickness of the glass cloth is within the above range, it is easy to obtain a glass cloth suitable as an insulating material. The lower limit of the thickness of the glass cloth may be more preferably not less than 5 μm, or not less than 10 μm.

[0017] <Dielectric tangent of glass cloth> The glass cloth has a dielectric loss tangent of 0.00200 or less at 10 GHz, measured by the method described in the Examples. Since the dielectric loss tangent of such a glass cloth increases over time due to the influence of water in the storage environment even at a temperature of 100°C or less, the increase in the dielectric loss tangent of the glass cloth can be suppressed by setting the average dew point temperature of the storage environment of the glass cloth to 18°C ​​dp or less. Note that the "storage environment" here means the atmosphere (gas) with 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, or 0.00030 or more. By having the dielectric loss tangent of the glass cloth within the above range, the glass cloth is easily affected by the moisture around the glass cloth in the storage environment, and therefore the effect of suppressing the increase in the dielectric loss tangent is easily obtained.

[0019] Glass thread The glass yarn constituting the glass cloth is preferably obtained by using low dielectric glass as a raw material. The low dielectric glass yarn more preferably has a silicon (Si) content of 95.0% by mass or more and 100% by mass or less in terms of SiO2. By using such glass yarn, the dielectric properties of the obtained glass cloth can be improved. In addition, in such glass yarn, the dielectric tangent of the glass cloth increases significantly over time, so that the effect of suppressing the increase in the dielectric tangent is easily obtained. From the viewpoint of improving the 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 or more and 9.0 μm or less, more preferably 2.5 μm or more and 7.5 μm or less, even more preferably 3.5 μm or more and 7.0 μm or less, even more preferably 3.5 μm or more and 6.0 μm or less, and particularly preferably 3.5 μm or more and 5.0 μm or less. When the filament diameter is equal to or more than the lower limit, the filament breaking strength is easily ensured, and fluff is less likely to occur in the obtained glass cloth. In addition, when the filament diameter is less than the upper limit, the mass of the glass cloth can be prevented from becoming too large, and therefore, the glass cloth is easily transported or processed.

[0021] <Silane coupling agent> The glass cloth preferably has a surface treatment agent containing a silane coupling agent on its surface. More specifically, the glass yarn (including glass filament) constituting the glass cloth is preferably surface-treated with a surface treatment agent containing a silane coupling agent. When the glass cloth has a surface treatment agent, the reactivity with the matrix resin tends to be improved. In addition, the glass cloth is less susceptible to the influence of moisture during storage, so that the increase in the dielectric tangent over time can be more effectively suppressed.

[0022] Examples of the silane coupling agent include a silane coupling agent represented 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 an unsaturated double bond group having radical reactivity, such as a carbon-carbon double bond having radical reactivity, each Y is independently an alkoxy group, n is an integer of 1 to 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 a silane coupling agent represented by the following formula:

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

[0024] Regarding Y in the above formula (1), the alkoxy group is preferably an alkoxy group having 1 to 5 carbon atoms (having 1, 2, 3, 4 or 5 carbon atoms) in order to stabilize the glass cloth.

[0025] As a surface treatment agent, the silane coupling agent shown in formula (1) may be used alone or in a mixture of two or more silane coupling agents having different X in formula (1). In addition, as the silane coupling agent shown in formula (1), for example, vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 5-hexenyltrimethoxysilane, etc. may be used alone or as a mixture thereof.

[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 particularly preferable to use two or more silane coupling agents having different molecular weights. By treating the glass fiber surface with two or more silane coupling agents having different molecular weights, the density of the treatment agent on the glass surface tends to increase, and the reactivity with the matrix resin tends to be further improved.

[0027] From the viewpoint of not inhibiting reactivity with resin, the silane coupling agent is preferably non-ionic. Among non-ionic silane coupling agents, silane coupling agents having at least one group selected from the group consisting of vinyl group, methacryloxy group, and acryloxy group are preferred, and silane coupling agents having at least one methacryloxy group or acryloxy group are particularly preferred. By not inhibiting reactivity with resin, the heat resistance and reliability of the printed wiring board can be improved.

[0028] <Ignition loss value> The ignition loss value 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. If the ignition loss value is within the above range, it is easy to obtain a glass cloth that exhibits a low dielectric tangent. Here, the ignition loss value is measured in accordance with JIS R3420.

[0029] <Glass cloth storage> The method for storing the glass cloth includes storing the glass cloth in an atmosphere in which 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. Note that the "storage environment" here means the atmosphere with 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 an increase in the dielectric tangent of the glass cloth over time due to water present in the storage environment.

[0030] The storage period of the glass cloth, that is, the period during which the storage environment in the present disclosure is maintained, is not particularly limited, but is preferably 30 days or more and 5 years or less 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. In addition, from the viewpoint of reducing storage costs, the upper limit of the storage period of 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 effect of maintaining the storage environment can be sufficiently obtained. The longer the storage period, the more remarkable the effect of suppressing the increase in dielectric tangent can be obtained.

[0031] <Average dew point in the storage environment for glass cloth> The method for storing the glass cloth is such that the average dew point under atmospheric pressure in the storage environment of the glass cloth is 18°C ​​dp or less. The average dew point is the average dew point during the storage period. Preferably, the dew point of the storage environment is controlled to be maintained at 18°C ​​dp or less throughout the entire storage period. When the average dew point is 18°C ​​dp or less, it is possible to prevent the dielectric tangent of the glass cloth from increasing over time. The average dew point is preferably -50°C dp or more and 18°C ​​dp or less. The lower limit of the average dew point may more preferably be -40°C dp or more, -32°C dp or more, -30°C dp or more, -20°C dp or more, -10°C dp or more, 0°C dp or more, 10°C dp or more, or 13°C dp or more. The upper limit of the average dew point, which can be arbitrarily combined with the lower limit, may more preferably be 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 method for storing glass cloth, the dew point may exceed 18°C ​​dp during part of the storage period, so long as the average dew point is 18°C ​​dp or less. Preferably, the dew point of the storage environment is controlled to be maintained at 18°C ​​dp or less throughout the entire storage period. The method for controlling the average dew point within the above range can use known humidity control methods, humidity control media, humidity control mechanisms, and humidity control devices. For example, (1) using a moisture absorbent, (2) replacing the surrounding atmosphere with a gas (e.g., dry gas) having a predetermined moisture content, (3) dehumidifying the surrounding atmosphere by utilizing condensation at low temperatures, (4) reducing the pressure to make the surrounding atmosphere have a predetermined moisture content, and (5) a combination of these.

[0033] The dew point can be controlled continuously or intermittently (regularly or irregularly) in an open or closed system, as long as the average dew point is controlled within the above range. For example, the above controls (1) to (5) can be continuously performed in a closed system (e.g., in a sealed packaging material (packaging material)), intermittently performed in a closed system (e.g., only in seasons or weather days when the dew point is likely to rise), or continuously controlled in an open system to change the dew point around the glass cloth. When the dew point is maintained by continuous humidity control, it is preferable to use a moisture absorbent, replacement with dry gas, a dehumidifier, or the like.

[0034] Moisture absorbent When a moisture absorbent is used to control the dew point, the type of moisture absorbent is not limited as long as the average dew point can be controlled within the above range. From the viewpoint of moisture absorption, the moisture absorbent is preferably at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccant, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate. Among them, at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, and calcined diatomaceous earth is preferable. In addition, from the viewpoint of the occupied space and packaging (packaging) form, it is preferable to use a sheet-shaped moisture absorbent.

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

[0036] The amount of moisture absorbent used becomes more important as the storage period becomes longer. If the amount of moisture absorbent is appropriate, the dew point of the storage environment can be maintained during the long storage period, and the increase in the dielectric tangent can be easily suppressed. The dew point of the storage environment, i.e., the amount of water vapor present inside the package, is affected by the water vapor transmission rate of the packaging material, the surface area of ​​the package, as well as the material of the packaging material, the external temperature and humidity of the storage environment, and the type, shape and amount of the moisture absorbent, etc., so it is difficult to estimate an appropriate amount of moisture absorbent from the start of storage and seal it to form a package. In particular, the water vapor transmission rate of the packaging material changes due to the influence of the temperature and humidity of the surrounding environment, but the degree of this varies depending on the material of the packaging material, making it more difficult to seal in an appropriate amount of moisture absorbent. However, by using the following formula, when manufacturing a package containing a moisture absorbent, the water vapor transmission rate of the packaging material, the surface area of ​​the package, and the amount of moisture absorbent can be controlled within a predetermined range, making it easier to control the rate at which the dew point inside the storage environment changes relative to the external environment (dew point change rate). First, the amount of water vapor that can penetrate into the inside of a package is expressed as the water vapor transmission rate (WVTR) x the surface area of ​​the package x the number of days of storage. Considering that the WVTR changes depending on the temperature and humidity of the surrounding environment, the amount of water vapor that can penetrate into the inside of a package can be simply expressed by the following formula, where WVTR is the water vapor transmission rate at a measurement temperature of 40°C and a measurement humidity of 90% Rh (dew point of approximately 38°C dp). (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 a package by a moisture absorbent is affected by the type, shape, amount, etc. of the moisture absorbent, but can be simply expressed by the following formula. 0.26 x amount of moisture absorbent enclosed [g] At this time, it is preferable that the amount of water vapor that can enter the inside of the package is equal to or less than the maximum amount of moisture that can be removed from the inside of the package by the moisture absorbent, that is, it is preferable that the following formula is satisfied. (WVTR[g / (m 2 ×24hr)] × package surface area [m 2]) × (external dew point of storage environment [℃dp] / 38) × (external temperature of storage environment [℃] / 40) × number of storage days ≦ 0.26 × amount of moisture absorbent enclosed [g] Furthermore, in the above formula, when the external environmental temperature is 30°C, the external dew point of the storage environment is 24°Cdp, and the number of storage days is 180 days, it is preferable to adjust the amount of moisture absorbent so that the value calculated by the following formula (2) is 0.0030 or less. This makes it possible to encapsulate an appropriate amount of moisture absorbent in accordance with the configuration of the package, making it easier to control changes in the dew point of the storage environment. WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ] / Amount of moisture absorbent enclosed [g] (2) However, if the packaging material is composed of two or more packaging materials with different water vapor permeabilities, the "WVTR [g / (m 2 ×24hr)] × package surface area [m 2 ]" is the "WVTR[g / (m 2 ×24hr)] × package surface area [m 2 The value calculated by formula (2) is more preferably 0.0023 or less, further preferably 0.0012 or less, and particularly preferably 0.0005 or less. The value calculated by formula (2) may be 0.

[0037] In the present disclosure, the rate of change in dew point within a package having a moisture absorbent therein is defined by the following formula. Dew point change rate = (storage environment dew point after 365 days of storage (℃dp) - initial dew point of storage environment (℃dp)) / (external environment average dew point of packaging material (℃dp) - storage environment dew point after 365 days of storage (℃dp)) The smaller the dew point change rate in the package, the greater the effect of controlling the storage environment by the packaging material and desiccant. The dew point change rate in the package is evaluated by the above formula, and the dew point change rate in the package after 365 days from 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 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) having a dew point temperature of 18°C ​​dp or less. With such a dry gas, it is easy to control the average dew point of the storage environment of the glass cloth to be 18°C ​​dp or less. The dew point temperature of the dry gas is preferably -60°C dp or more and 18°C ​​dp or less. The lower limit of the dew point temperature of the dry gas may more preferably be -50°C dp or more, -40°C dp or more, or -30°C dp or more. The upper limit of the dew point temperature of the dry gas may more preferably be 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.

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

[0040] When a dehumidifier is used to control the dew point, the dehumidifier is not limited as long as it can control the average dew point within the above range. For example, a compressor type dehumidifier that utilizes condensation at low temperatures and a desiccant type (zeolite type) dehumidifier that repeatedly regenerates a dehumidifying agent by heat can be used.

[0041] In order to suppress the change in the dew point over time, it is preferable to store the glass cloth in a sealed storage environment. As a sealing method, it is particularly preferable to suppress the inflow of moisture into the storage environment. The specific storage form will be described later.

[0042] <Average temperature in the storage environment for glass cloth> The glass cloth is stored in an atmosphere in which the average temperature of the storage environment of the glass cloth is 100°C or less. When the average temperature is 100°C or less, the dielectric tangent of the glass cloth can be effectively suppressed from increasing over time. The average temperature of the glass cloth storage environment when storing the glass cloth is preferably 0°C or more and 100°C or less. The upper limit of the average temperature is preferably 50°C or less, more preferably 40°C or less, even more preferably 35°C or less, still more preferably 30°C or less, and particularly preferably 25°C or less. The lower limit of the average temperature may be preferably 10°C or more, or 20°C or more. Preferably, the temperature of the storage environment is controlled so as to be maintained at 100°C or less throughout the entire storage period. More preferably, the temperature is controlled to be 40°C or less, even more preferably 35°C or less, still more preferably 30°C or less, and particularly preferably 30°C or less throughout the storage period. Preferably, the temperature of the storage environment is controlled so as to be 0°C or more, 10°C or more, or 20°C or more throughout the storage period.

[0043] <Pressure in the storage environment of glass cloth> When reducing pressure to control the dew point, atmospheric pressure (10 5 The method for controlling the air pressure in the storage environment of the glass cloth to a reduced pressure less than atmospheric pressure is not limited as long as the average dew point can be controlled within the above range, but known reduced pressure control methods, reduced pressure control media, reduced pressure control mechanisms, reduced pressure control devices, etc. can be used, for example, a vacuum pump.

[0044] The air pressure can be maintained by a known method as long as the storage environment of the glass cloth is maintained at a reduced pressure below atmospheric pressure. For example, the storage environment may be reduced in pressure continuously or intermittently (periodically or irregularly), or the glass cloth may be sealed in a packaging material (packaging material) whose pressure has been reduced to suppress changes in air pressure. The air pressure around the glass cloth when storing or packaging the glass cloth is preferably 10 4 Pa or less, more preferably 10 3The lower limit of the atmospheric pressure is not particularly limited, but is preferably more than 0 Pa or 10 Pa or more.

[0045] <Storage form> The storage form of the glass cloth is not particularly limited as long as the above-mentioned storage environment is maintained, and examples thereof include storage in a room such as a storage room, storage in a package wrapped in a packaging material, and a combination thereof. In the present disclosure, the terms "packaging" and "packing" are used interchangeably as terms meaning to wrap an object. Examples of packaging materials include boxes and films. In each case, it is preferable to control the storage environment, i.e., the average dew point and temperature of the atmosphere in direct contact with the glass cloth, and optionally the pressure, within the above ranges. In addition, from the viewpoint of avoiding wrinkles in the glass cloth and reducing the storage space, it is preferable to store the glass cloth in a rolled state. In the rolled state, it is easy to minimize the area where the storage environment and the external environment come into contact and to reduce the internal air volume during packaging, and the increase in the dielectric tangent over time can be more effectively suppressed.

[0046] The storage room and packaging material for storing the glass cloth preferably have high sealing properties in order to easily maintain the average dew point and temperature. In addition to or instead of being highly sealed, the storage room and packaging material are preferably configured to dehumidify so as to maintain the average dew point inside (storage environment) at 18°C ​​dp or less. That is, it is preferable that the storage room and packaging body themselves are provided with the dew point control means as described above. The average dew point inside (storage environment) is preferably -50°C dp or more and 18°C ​​dp or less. The lower limit of the average dew point inside (storage environment) may more preferably be -40°C dp or more, -32°C dp or more, -30°C dp or more, -20°C dp or more, -10°C dp or more, 0°C dp or more, 10°C dp or more, or 13°C dp or more. The upper limit of the average internal (storage environment) dew point, which can be arbitrarily combined with the above lower limit, may more preferably be 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.

[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 / (m 2 ×24hr) or less, more preferably 4g / (m 2 × 24hr) or less, more preferably 2g / (m 2 × 24hr) or less, and even more preferably 1g / (m 2 × 24hr), and particularly preferably 0.3 g / (m 2 × 24hr), and particularly preferably 0.1 g / (m 2 ×24hr) or less. The water vapor permeability of the packaging material is 8g / (m 2 × 24hr), the amount of moisture that permeates is small, making it easier to control the dew point. The lower limit of water vapor permeability is 0g / (m 2 ×24hr) or more, e.g. 0g / (m 2 ×24hr).

[0048] When the glass cloth in a roll state is stored as a package wrapped in a box and / or film-like packaging material, it is preferable to enclose a moisture absorbent in the package. It is more preferable to enclose a moisture absorbent between the roll and the packaging material. This allows the moisture absorbent to absorb moisture inside the package and also absorb moisture that has permeated the box and / or film-like packaging material during storage and flowed into the storage environment.

[0049] From the viewpoint of facilitating the maintenance of the dew point and temperature, it is preferable that the glass cloth is packaged in a box and / or a film-like packaging material, and the opening is sealed. The sealing can be performed, for example, by thermocompression bonding the opening. The sealing means a state in which the opening is tightly closed without any gaps, and the temperature, dew point, and air pressure in the storage environment of the glass cloth can be controlled below a certain standard. The sealed state is preferably sealed to prevent the intrusion of solids, liquids, and gases. By suppressing the intrusion of solids, liquids, and gases, the effect of suppressing the increase in the dielectric tangent of the glass cloth can be easily obtained.

[0050] When a box is used as the packaging material, the box is not limited as long as the water vapor permeability satisfies the above range, but may be made of a material capable of sealing the opening, such as a metal, plastic, wooden, or cardboard box, or a combination thereof. From the viewpoint of easily satisfying the above range of water vapor permeability and being easily reusable, the material is preferably made of metal or plastic, and more preferably metal. Here, the box refers to a movable, sealed container for blocking the glass cloth from the outside air. One or more pieces of glass cloth may be stored in the box.

[0051] When a film is used as a packaging material, the film is not limited as long as the water vapor permeability satisfies the above range, and examples thereof include ceramic deposition film, aluminum deposition film, aluminum foil, and aluminum laminate film. Aluminum foil and aluminum laminate film are preferred from the viewpoint that the water vapor permeability is likely to satisfy the above range. 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. When the thickness is 50 μm or more, the water vapor permeability is likely to be small, and pinholes due to wrinkles, scratches, etc. are unlikely to occur. 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] The glass cloth is preferably stored in a roll (also simply called a "glass cloth roll") wound around a hollow columnar core tube having a columnar cavity (hollow portion) in the center, as a package wrapped in a film. When handling the glass cloth roll, such as transporting it, a support rod is often inserted into the hollow portion of the core tube of the roll to lift the roll. From the viewpoint of maintaining the above-mentioned storage environment, it is preferable to package the glass cloth roll with a packaging material having a minimum surface area, but this method makes it impossible to use the hollow portion of the core tube when handling the glass cloth roll, making handling complicated. Therefore, from the viewpoint of ease of handling the glass cloth roll, it is preferable that the glass cloth roll is configured such that the film-like packaging material has a recess extending from one or both ends of the core tube into the hollow portion, or the film-like packaging material is annular (donut-shaped) penetrating the hollow portion of the core tube, so that a support rod can be inserted into the hollow portion of the core tube. Alternatively, from the viewpoint of ease of handling of the glass cloth roll, it is preferred that the glass cloth is sealed from the external environment by a film-like packaging material and a core tube.

[0053] FIG. 1 is a schematic diagram showing a cross section of the glass cloth package of the present disclosure in the axial direction of the core tube. For example, as shown in FIG. 1(1a), the glass cloth package 10 may have a hollow columnar core tube 11, a glass cloth 12 wound around the core tube 11, and a film 13 surrounding the entire core tube 11 and the glass cloth 12. The film 13 has a recess 14 extending from one end of the core tube 11 toward the inside of the hollow portion, so that a support rod can be inserted into the hollow portion. Also, as shown in FIG. 1(1b), the glass cloth package 10 may have an outer film 13a covering the outside of the glass cloth 12 and a hollow inner film 13b penetrating 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 thermocompression or the like. As a result, the films 13a and 13b have a ring-shaped form that surrounds the entire core tube 11 and the glass cloth 12 as a whole. When the packaging material is in a ring shape, the external environment penetrates the hollow part of the core tube, so that the support rod can penetrate the hollow part from both sides of the packaging body, and the handling property is further improved. The joining of the films is not particularly limited as long as the openings can be closely attached to each other to eliminate gaps, and for example, a method of attaching them with heat compression, tape, adhesive, etc. can be mentioned. Alternatively, as shown in FIG. 1 (1c), the film 13 covering the outside of the glass cloth 12 and the core tube 11 may be joined at a joining part 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 form, the external environment penetrates the hollow part of the core tube, so that the support rod can penetrate the hollow part from both sides of the packaging body, and since there is no film inside the core tube, pinholes and the like are unlikely to occur when inserting and removing the support rod or when lifting and transporting the roll, and the handling property is further improved. The method of joining the film-like packaging material to the core tube is not particularly limited as long as it can seal the opening and eliminate any gaps. For example, the opening may be attached with tape, adhesive, or the like.

[0054] From the viewpoint of facilitating insertion of the support rod, the ratio of the volume of the space inside the film-like packaging body to the volume of the hollow part of the core tube 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 of the inside of the packaging body relative to the volume of the hollow part may be 0% or more. For example, in the form shown in FIG. 1(1c), the volume of the inside of the packaging body 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 portion) in the center from the viewpoint of handling during transportation and post-processing. The material of the core tube can be paper, resin, fiber reinforced plastics (hereinafter referred to as "FRP"), metal, etc., and from the viewpoint of preventing the inclusion of metal foreign matter in the glass cloth, paper, resin, and FRP are preferable. The core tube generally has a certain thickness from the viewpoint of the balance between weight and strength. In particular, the weight of the glass cloth itself is large in a glass cloth roll, while in a core tube with a small diameter, the glass cloth is strongly bent, so that the core tube has been made thicker and lighter. Since the core tube is thicker than a film or the like, the permeation of water vapor through the core tube has not been considered until now. However, as a result of further investigation, it was found that water vapor can pass through even core tubes made of paper, resin, and FRP due to the fact that the overall thickness of the core tube is thin in order to reduce its weight, that the core tube is made by combining thin materials, and that there are joints when combining the materials, etc. Therefore, it is preferable to use a core tube with low water vapor permeability.

[0056] From the viewpoint of easily controlling the amount of moisture 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 / (m 2 ×24hr) or less, more preferably 4g / (m 2 × 24hr) or less, more preferably 2g / (m 2 × 24hr) or less, and even more preferably 1g / (m 2 × 24hr), and particularly preferably 0.3 g / (m2 × 24hr), and particularly preferably 0.1 g / (m 2 ×24hr) or less. The water vapor permeability of the core tube is 8g / (m 2 × 24hr), the amount of moisture that permeates is small, making it easier to control the dew point. The lower limit of water vapor permeability is 0g / (m 2 ×24hr) or more, e.g. 0g / (m 2 Methods for controlling the water vapor transmission rate of the core tube within the above range include coating the core tube with a moisture-proof paint, performing vapor deposition plating, increasing the thickness of the core tube, using a material with low water vapor transmission rate for the core tube, wrapping a film with low water vapor transmission rate around the core tube, and the like.

[0057] <Package surface area> The smaller the surface area of ​​the glass cloth package wrapped in the packaging material, the easier it is to maintain the storage environment. The surface area of ​​the package is not limited as long as the dew point of the storage environment satisfies the range of the present disclosure, but is preferably 10 m 2 Less than or equal to 7m, preferably 2 Less than 5m, more preferably 2 Less than 4m, more preferably 2 The lower limit of the surface area of ​​the package is not limited as long as the glass cloth can be sealed from the external environment. In the present disclosure, the "surface area of ​​the package" means, for example, the area of ​​the film when the glass cloth is sealed from the external environment by a film, the area of ​​the outer surface of the box when the glass cloth is sealed from the external environment by a 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 when the glass cloth is sealed from the external environment by a film and a core tube.

[0058] <Storage room> The storage room for storing the glass cloth means a room where the dew point and temperature are controlled. From the viewpoint of space saving, the room is preferably a room where a plurality of glass cloths are stored together in a roll state. The glass cloth in a roll state may be stored in the storage room as a package wrapped in a box and / or a film-like packaging material.

[0059] <<Glass Cloth Manufacturing Method>> The method for producing a glass cloth used in the method for storing a glass cloth of the present disclosure includes a step of weaving a glass thread containing a plurality of glass filaments as a warp thread and a weft thread to obtain a glass cloth. The method for producing a glass cloth may further include a step of subjecting the glass thread or the glass cloth to a thermal deoiling treatment (heat cleaning) and a step of treating the glass thread or the glass cloth with a surface treatment agent. The method for producing a glass cloth may further include at least one of a step of opening the glass cloth and a step of packaging the glass cloth in a packaging material (such as a box and a film).

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

[0061] <Heat deoiling process> The thermal deoiling step can be performed on glass yarns, and can also be performed on woven glass cloth. In other words, the step of weaving glass yarns to obtain glass cloth may be performed before, during, or after the thermal deoiling step. The thermal deoiling step can be performed in any of the following ways: (1) a method of deoiling glass yarns or glass cloth (hereinafter, simply referred to as "glass" in this step) at a relatively low temperature (e.g., less than 600°C) for a long period of time (e.g., 24 hours or more), and (2) a method of deoiling glass at a relatively high temperature (e.g., 600°C to 1600°C) for a long period of time or a short period of time (e.g., less than 24 hours). From the viewpoint of obtaining a glass cloth having an excellent dielectric loss tangent, it is preferable to use the method (2). In particular, a glass cloth composed of glass yarns having a Si content of 95.0 mass% or more and 100 mass% or less in terms of SiO2 may be deoiled by heating at a temperature of 600°C or more. 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 thermal deoiling is preferably 100° C. or more and 500° C. or less, more preferably 250° C. or more and 450° C. or less, and even more preferably 350° C. or more and 450° C. or less. The heating time for thermal deoiling in the case of (1) can be appropriately selected and is, for example, preferably 24 hours or more and 300 hours or less, more preferably 48 hours or more and 200 hours or less, and even more preferably 72 hours or more and 150 hours or less. If the combination of the thermal deoiling temperature and time is within the above ranges, the sizing agent adhering to the glass can be easily and sufficiently removed.

[0063] On the other hand, in the case of (2) heating at a relatively high temperature, the temperature of the thermal deoiling is preferably 600°C or more and 1500°C or less, more preferably 800°C or more and 1300°C or less, and even more preferably 900°C or more and 1100°C or less. If the thermal deoiling temperature is 600°C or more, organic substances such as the residue of the glue adhering to the glass can be easily removed sufficiently, so that the dielectric tangent of the glass cloth can be easily lowered and the removal time can be shortened. On the other hand, if the thermal deoiling temperature is 1500°C or less, it is easy to suppress the devitrification phenomenon of the glass, and the strength reduction of the glass cloth can be effectively prevented. In addition, the heating time in the thermal deoiling in the case of (2) can be appropriately selected, and is, for example, preferably 3 seconds or more and 72 hours or less, more preferably 3 seconds or more and 12 hours or less, even more preferably 3 seconds or more and 2 hours or less, particularly preferably 3 seconds or more and 10 minutes or less, and particularly preferably 3 seconds or more and 300 seconds or less.

[0064] The heating means for thermal deoiling can be any known heating method, heating medium, heating mechanism, heating device, heating component, etc., as long as it is a method that can suitably control the thermal deoiling temperature. For example, it may be (1) a method of heating the glass in a heating furnace, (2) a method of bringing the glass into contact with a heating part, (3) a method of applying high-temperature steam to the glass, etc. Heating can be performed sequentially or continuously, in a closed system or an open system, or a combination of a closed system and an open system.

[0065] In the case of a closed system, it is preferable to place the glass in a heating furnace from the viewpoint of suitable heating by a heating means, and in that case, it is preferable to heat the glass cloth while storing it in a rolled state from the viewpoint of storage space and heating range. It is also preferable to heat the glass while conveying it in the heating furnace from the viewpoint of increasing the efficiency of removing organic substances and shortening the time required for removing organic substances.

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

[0067] The heating means of the heating furnace may be various means such as an electric heater or a burner, and a gas type single radiant tube burner or an electric heater is preferred. Heating may be performed by combining a plurality of means.

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

[0069] The heating furnace may be of either a batch type, which can accommodate glass (e.g., a roll of glass cloth) and heat it at a predetermined atmospheric temperature, or a continuous type, which can heat the glass while continuously passing it through the heating furnace (e.g., heating while conveying it by roll-to-roll). In order to efficiently remove organic matter adhering to the glass surface, the heating furnace is preferably of a continuous type.

[0070] The glass may be heated using the above-mentioned heating furnace, but from the viewpoint of low running costs, the glass may be heated by contacting a member heated to a predetermined temperature with the glass.

[0071] The shape of the contact member is not particularly limited as long as it can heat the glass while suitably controlling the heating deoiling temperature, but a roll shape is preferred for ease of transporting the glass (heating roll method). As a member capable of heating glass in a roll shape, a roll that heats by induction heating is preferred, which can be used in high temperature ranges and has relatively little temperature variation in the width direction. When heating glass with a contact member, it is considered that the temperature of the contact member and the surface temperature of the glass are roughly the same.

[0072] As the glass is continuously heated, carbides may adhere to the heating roll. In order to remove the carbides adhering to the heating roll, the heating roll method is preferably provided with a mechanism for removing the adhering foreign matter, such as a blade.

[0073] Surface treatment process The surface treatment step can be performed on glass yarns, or on woven glass cloth. In other words, the step of weaving glass yarns to obtain glass cloth may be performed before, during, or after the surface treatment step. The surface treatment step can include, for example, a coating step of attaching a silane coupling agent to the surface of the glass yarns or glass cloth (hereinafter, also simply referred to as "glass" in this step) using a treatment liquid having a concentration of 0.1% by mass to 0.5% by mass. The surface treatment step can 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 perform a suitable surface treatment of the glass.

[0074] Examples of the method for applying the treatment liquid to the glass in the coating step include (a) a method in which the glass is immersed or passed through the treatment liquid stored in a bath (hereinafter referred to as the "immersion method"); and (b) a method in which the treatment liquid is applied to the glass using a roll coater, a die coater, a gravure coater, or the like. When the immersion method is adopted, it is preferable to select the immersion time of the glass in the treatment liquid to be 0.5 seconds or more and 1 minute or less. When the immersion method is adopted, the glass can be passed through the treatment liquid at a conveying speed of 10 m / min to 50 m / min while applying a predetermined tension (for example, 100 N to 250 N) to the glass. After the treatment liquid is applied to the glass, the solvent contained in the treatment liquid can be heated and dried by a method such as hot air or electromagnetic waves. In order to make it easier to apply the surface treatment agent uniformly to the glass surface, it is preferable to squeeze the glass cloth with a constant pressure using a rubber roller after immersing it in the surface treatment liquid.

[0075] The concentration of the surface treatment agent in the treatment liquid is preferably 0.1 mass % to 0.5 mass %, more preferably 0.1 mass % to 0.45 mass %, and even more preferably 0.1 mass % to 0.4 mass %, based on the total mass of the treatment liquid, which makes it easier to perform the surface treatment of the glass more suitably.

[0076] In the fixing step, the heating and drying temperature is preferably 80° C. or higher, more preferably 90° C. or higher, so that the reaction between the silane coupling agent and the glass is sufficiently carried out, and is preferably 300° C. or lower, more preferably 180° C. or lower, so as to prevent deterioration of the organic functional group of the silane coupling agent.

[0077] <Opening process> The method for producing a glass cloth may further include a step of opening the glass cloth. As a method for opening the glass cloth in the opening step, for example, a method of opening the glass cloth with spray water (high pressure water opening), a vibro washer, ultrasonic water, a mangle, or the like can be adopted. In many cases, the composition of the glass cloth does not usually change before and after opening.

[0078] <Packaging process> The manufacturing method of the glass cloth may further include a step of packaging the glass cloth with a packaging material, for example, a 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, so they will not be described here. In the packaging step, it is preferable to control the dew point and temperature of the environment in direct contact with the glass cloth, and optionally the pressure, etc., to the storage environment of the present disclosure before packaging. The storage environment has been described above, so it will not be described here. In addition, as a sealing method, for example, a method of wrapping the glass cloth with a film and thermocompressing the opening, a method of putting the glass cloth in a box and sealing the opening to eliminate gaps, a method of attaching the opening with tape, etc. can be used.

[0079] When glass cloth in a roll state wound around a hollow columnar core tube is wrapped with a film, for example, the glass cloth roll is covered with a film, the opening is heat-pressed to seal, and the excess film is pushed into the hollow from one or both ends of the core tube, thereby forming a recess extending from one or both ends into the hollow. A method of wrapping in an annular shape with the hollow of the core tube penetrating therethrough includes inserting a tubular film into the hollow of the core tube of the glass cloth roll, covering the glass cloth roll with another film, and heat-pressing the tubular film and the tubular film penetrating the hollow to seal the opening. A method of wrapping by joining the film and the core tube includes, for example, attaching the film to the surface of the core tube with tape without any gaps.

[0080] The above steps do not necessarily have to be performed in a manner that can be distinguished as separate steps, and a plurality of steps can be performed together (simultaneously). The method for producing glass cloth can also include any steps other than the above steps. For example, a slitting step can be included after the fiber-spreading step. If possible, the order of the above steps can be changed.

[0081] Glass cloth packaging The glass cloth package of the present disclosure includes a packaging material and a glass cloth housed inside the packaging material. The glass cloth is made of glass yarns including a plurality of filaments as warp and weft yarns, 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 / (m 2 ×24hr) or less. In the past, it was thought that the dielectric tangent of a glass cloth having a dielectric tangent of 0.00200 or less at 10 GHz would not change over time even if the glass cloth was stored for a long period of time in a temperature range of less than 100°C because the reaction in which the Si-O-Si bond is cleaved by moisture to generate Si-OH groups was not activated in the temperature range of less than 100°C. Therefore, the dielectric tangent of the glass cloth may increase over time even if the glass cloth has a low dielectric tangent at the time of manufacture without any particular consideration being given to the storage form of the glass cloth. In this regard, the glass cloth package of the present disclosure can suppress the increase in the dielectric tangent of the glass cloth over time because the Si-O-Si bond is cleaved by moisture that has entered the storage environment from the external environment to generate Si-OH groups. In the present disclosure, "suppression" does not mean that the dielectric tangent does not increase at all, but it is sufficient that the increase in the dielectric tangent is suppressed to a certain extent.

[0082] <Glass cloth> Details of the glass cloth, the dielectric tangent of the glass cloth, the glass yarn, the silane coupling agent, and the ignition loss value in the glass cloth package are as described in <Glass cloth> to <Ignition loss value> in the above <Storage method of glass cloth>, so these descriptions are also used for the glass cloth package.

[0083] <Packaging material> The packaging material can be sealed with glass cloth. The water vapor permeability of the packaging material (boxes, films, etc.) measured under conditions of 40°C and 90% Rh is 8g / (m 2× 24hr) or less. Sealed means that the opening is tightly closed without gaps, and the temperature, dew point, and air pressure in the glass cloth package can be controlled below a certain standard. The sealed state is preferably sealed to prevent the intrusion of solids, liquids, and gases. By suppressing the intrusion of solids, liquids, and gases, the effect of suppressing the increase in the dielectric tangent of the glass cloth described in the present disclosure is easily obtained. The packaging material is not limited as long as it satisfies the above-mentioned configuration, and examples thereof include film and box-shaped packaging materials.

[0084] <Water vapor permeability> The packaging material has a water vapor permeability of 8g / (m2) at a measurement temperature of 40°C and a measurement humidity of 90%Rh. 2 With such a packaging material, the amount of moisture inside the packaging material can be controlled, and an increase in the dielectric tangent of the glass cloth over time due to the water present in the packaging material can be suppressed. From the viewpoint of easily controlling 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 / (m 2 ×24hr) or less, more preferably 4g / (m 2 × 24hr) or less, more preferably 2g / (m 2 × 24hr) or less, and even more preferably 1g / (m 2 × 24hr), and particularly preferably 0.3 g / (m 2 ×24hr) or less, most preferably 0.1g / (m 2 ×24hr) or less. The water vapor permeability of the packaging material is 8g / (m 2 × 24hr) or less, the amount of moisture that permeates is small, making it easier to control the amount of moisture inside the packaging material. The lower limit of water vapor permeability is 0g / (m 2 ×24hr) or more, e.g. 0g / (m 2 ×24hr).

[0085] <film> Films can also be used as packaging materials. As long as the water vapor permeability satisfies the above range, there are no limitations, and examples include ceramic vapor deposition films, aluminum vapor deposition films, aluminum foils, and aluminum laminated films. Aluminum foils and aluminum laminated films are preferred from the viewpoint that the water vapor permeability is likely to satisfy the above range. 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. When the thickness is 50 μm or more, the water vapor permeability is likely to be small, and pinholes due to wrinkles, scratches, etc. are unlikely to occur. 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] The glass cloth is preferably a packaged body wrapped in a film in a roll (also simply called a "glass cloth roll") wound around a hollow columnar core tube having a columnar cavity (hollow portion) in the center. For the same reason as described in "Packaging material" of "Method of storing glass cloth" above, the film preferably has a recess extending from one or both ends of the core tube into the hollow portion, or the film-like packaging material is preferably annular (donut-shaped) penetrating the hollow portion of the core tube, so that a support rod can be inserted into the hollow portion of the core tube. Alternatively, the glass cloth is preferably sealed from the external environment by the film-like packaging material and the core tube. Specific examples of these are, as described above, typically shown in, for example, Figs. 1(1a) to (1c).

[0087] From the viewpoint of facilitating insertion of the support rod, the ratio of the volume of the space inside the film-like packaging body to the volume of the hollow part of the core tube 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 of the inside of the packaging body relative to the volume of the hollow part may be 0% or more. For example, in the form shown in FIG. 1(1c), the volume of the inside of the packaging body relative to the volume of the hollow part is 0%.

[0088] <Core tube> For the same reasons as described above in the "Core Tube" section of the "Glass Cloth Storage Method", the core tube is preferably made of paper, resin, or FRP. The water vapor permeability of the core tube measured under conditions of 40°C and 90% Rh is preferably 8 g / (m 2 ×24hr) or less, more preferably 4g / (m 2 × 24hr) or less, more preferably 2g / (m 2 × 24hr) or less, and even more preferably 1g / (m 2 × 24hr), and particularly preferably 0.3 g / (m 2 × 24hr), and particularly preferably 0.1 g / (m 2 ×24hr) or less. The lower limit of water vapor permeability is 0g / (m 2 ×24hr) or more, e.g. 0g / (m 2 ×24hr).

[0089] <Box-shaped packaging material> The packaging material may be in the form of a box. As long as the water vapor permeability satisfies the above range, the packaging material is not limited, and may have a sealed opening, such as a metal, plastic, wooden, or cardboard box, or a combination of these. From the viewpoint of making the water vapor permeability easily satisfy the above range and being easily reusable, the material is preferably metal or plastic, and more preferably metal. The box here refers to a movable, sealed container for blocking the glass cloth from the outside air. One or more pieces of glass cloth may be stored in the box.

[0090] <Package surface area> For the same reasons as described in the "Core Tube" of the "Glass Cloth Storage Method" above, the surface area of ​​the package is not limited as long as the dew point of the storage environment satisfies the range of this disclosure, but is preferably 10 m 2 Less than or equal to 7m, preferably 2 Less than 5m, more preferably 2 Less than 4m, more preferably 2The lower limit of the surface area of ​​the package 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 package preferably has a dew point of 18°C ​​dp or less under the atmospheric pressure inside the package. In this disclosure, unless otherwise specified, the dew point refers to the dew point under the atmospheric pressure of the storage environment. When the dew point under the atmospheric pressure inside the package is 18°C ​​dp or less, the dielectric tangent of the glass cloth can be more effectively prevented from increasing over time. The dew point is preferably -50°C dp or more and 18°C ​​dp or less. The lower limit of the dew point may more preferably be -40°C dp or more, -32°C dp or more, -30°C dp or more, -20°C dp or more, -10°C dp or more, 0°C dp or more, 10°C dp or more, or 13°C dp or more. The upper limit of the dew point, which can be arbitrarily combined with the lower limit, may more preferably be 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] The method of controlling the dew point within the above range can use known humidity control methods, humidity control media, humidity control mechanisms, and humidity control devices. For example, (1) using a moisture absorbent, (2) replacing the atmosphere inside the packaging material with a gas (e.g., dry gas) having a predetermined moisture content, (3) dehumidifying the atmosphere inside the packaging material by using condensation at low temperatures, (4) reducing the pressure to make the atmosphere inside the packaging material have a predetermined moisture content, and (5) a combination of these. For example, by controlling the above (1) to (5) and sealing the packaging material, the effect of suppressing the increase in the dielectric tangent can be easily obtained.

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

[0094] Moisture absorbent It is preferable to enclose a moisture absorbent inside the packaging material of the glass cloth package, so that the moisture inside the packaging material can be absorbed and also the moisture that has permeated the packaging material and entered the packaging material during storage can be absorbed.

[0095] From the viewpoint of moisture absorbing power, the moisture absorbent is preferably at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccant, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate. Among them, at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, and calcined diatomaceous earth is preferable. In addition, from the viewpoint of occupied space and packaging (packaging) form, it is preferable to use a sheet-shaped moisture absorbent.

[0096] The amount of the moisture absorbent used is not limited, but it is preferable to use an appropriate amount depending on the moisture absorption capacity of the moisture absorbent (amount of moisture absorption and time of moisture absorption) and the storage period, etc. It is preferable to use an amount that is more than sufficient for the moisture absorption amount. In other words, it is preferable that the maximum amount of moisture that the moisture absorbent can absorb is greater than the amount of moisture in the atmosphere.

[0097] As described in the above section "Moisture absorbent" of "Glass cloth storage method", the amount of moisture absorbent enclosed is preferably 0.0030 or less, more preferably 0.0023 or less, further preferably 0.0012 or less, and particularly preferably 0.0005 or less, as calculated by the following formula (2). The value calculated by the following formula (2) may be 0. WVTR[g / (m 2 ×24hr)] × package surface area [m 2 ] / Amount of moisture absorbent enclosed [g] (2) {In formula (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 above in the section "Moisture absorbent" of "Glass cloth storage method", the dew point change rate in the package having the moisture absorbent therein is preferably 3.0 or less, more preferably 1.0 or less, even more preferably 0.50 or less, still more preferably 0.30 or less, particularly preferably 0.10 or less, or 0.02 or less. The dew point change rate may be a negative value.

[0099] <Dry gas> When dry gas is used 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°C ​​dp or less. With such dry gas, it is easy to control the dew point inside the packaging material to an atmosphere of 18°C ​​dp or less. The dew point temperature of the dry gas is preferably -60°C dp or more and 18°C ​​dp or less. The lower limit of the dew point temperature of the dry gas may more preferably be -50°C dp or more, -40°C dp or more, or -30°C dp or more. The upper limit of the dew point temperature of the dry gas may more preferably be 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.

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

[0101] <Temperature inside glass cloth packaging> The temperature in the packaging material of the glass cloth package is preferably 100°C or lower. When the temperature is 100°C or lower, the dielectric tangent of the glass cloth can be effectively prevented from increasing over time during long-term storage (e.g., 30 days or more). The temperature of the glass cloth storage environment (inside the packaging material) during storage of the glass cloth is preferably 0°C or higher and 100°C or lower. 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, still more preferably 30°C or lower, and particularly preferably 25°C or lower. The lower limit of the average temperature may be preferably 10°C or higher, or 20°C or higher.

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

[0103] For example, the pressure inside the packaging material is controlled to be reduced below atmospheric pressure, and the packaging material is sealed to easily suppress the increase in the dielectric tangent. 4 Pa or less, more preferably 10 3 The lower limit of the atmospheric pressure is not particularly limited, but is preferably more than 0 Pa or 10 Pa or more.

[0104] Storage Period The storage period of the glass cloth, that is, the period during which the sealing of the packaging material in the glass cloth package of the present disclosure is maintained, is not particularly limited, but is preferably 30 days or more and 5 years or less 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. In addition, from the viewpoint of reducing storage costs, the upper limit of the storage period of 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 effect of forming the glass cloth package of the present disclosure can be sufficiently obtained. The longer the storage period, the more remarkable the effect of suppressing the increase in dielectric tangent can be obtained.

[0105] <<Method for manufacturing glass cloth packaging>> The glass cloth package of the present disclosure can be produced by packaging the glass cloth produced by the method described in the above section "Glass cloth manufacturing method" by the method described in the above section "Packaging process," and these descriptions are incorporated herein by reference in the manufacturing method of the glass cloth package. EXAMPLES

[0106] Measurement and evaluation methods <Measuring method for basis weight (cloth weight)> The weight per unit area of ​​the glass cloth was determined by cutting the glass cloth to a predetermined size and dividing the weight by the sample area. 2 The operation of cutting out pieces of the glass cloth into pieces of the same size and measuring their weight was repeated 10 times, and the average value was regarded as the basis weight of each glass cloth.

[0107] <Method of measuring converted thickness> The glass cloth is a discontinuous planar body with air between the glass fibers. Therefore, the converted 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: Converted thickness (μm) = basis weight (g / m 2 )÷Density(g / cm 3 ) The converted thickness was calculated by the above method. This converted thickness was used for the measurement by the resonance method.

[0108] <Method of measuring dielectric tangent> The dielectric loss tangent of each glass cloth was determined in accordance with IEC 62562. Specifically, the glass cloth samples were sampled to a size required for measurement with a split cylinder resonator and stored in a thermo-hygrostatic oven at 23°C and 50% RH for 8 hours or more. The dielectric properties of the stored samples were measured at 10 GHz using a split cylinder resonator (manufactured by EM Lab) and an impedance analyzer (manufactured by Agilent Technologies). The measurement was 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 of fine ceramic materials used in microwave circuits in the microwave band.

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

[0110] <Temperature and dew point measurement method> Temperature and dew point were measured using a Vaisala DM70 handheld dew point meter. Depending on the dew point to be measured, a DMP74A or 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°C dp, and the DMP74B probe was used when the dew point was below -30°C dp. The average temperature and average dew point were measured by averaging the temperatures and dew points measured every 3 hours with the DM70.

[0111] <Pressure measurement method> A pressure gauge attached to the box was visually read to measure the pressure inside the box.

[0112] <Method for measuring water vapor transmission rate of packaging materials and core tubes> Measurement method A: For packaging materials with a thickness of 2 mm or less, such as plastic films, plastic sheets, and multi-layer materials containing plastic The thickness and water vapor permeability of the packaging material were measured in accordance with JIS K7130 and JIS K7129-1. The measurements were performed three times for each sample, and the average values ​​were taken as the thickness and water vapor permeability of the packaging material. The test pieces used were those that were visually free of wrinkles, folds, or pinholes and had a uniform thickness. Equipment: Water vapor transmission meter L80-5000 (Lyssy ISO-PE-Z91) Thickness gauge: ID-C1012C (Mitutoyo ISO-PE-Z78) ·Temperature / Humidity: 40℃・90%Rh ·Measurement area: approx. 50cm 2 Reference sample: PET 19μm thick (25.5g / (m 2 ×24hr) Measurement direction: Through the outer side of the glass cloth when wrapped

[0113] Measurement method B: When the packaging material is not subject to measurement method A and is not a core tube For packaging materials other than those covered by measurement method A, the weight of water vapor that penetrates into the packaging material was measured at a temperature of 40°C, with the humidity outside the packaging material at 90% Rh and the air inside kept dry and sealed. The weight of water vapor was measured per 24 hours of permeation time and per square meter of the packaging material's external surface area. 2The dew point was calculated per unit. Specifically, dry air with a dew point of -30℃ dp was sealed inside the packaging material, 800g of 1st class A desiccant of JIS Z 0701 (Desiccant for Packaging) or equivalent quality was placed inside, the temperature and dew point were measured, and the packaging material was sealed. If 800g of desiccant cannot be placed inside the packaging material, the weight of the desiccant is measured and the desiccant is placed so that the volume is more than half the volume of the packaging material. The sealed packaging material was then placed in a thermohygrostat at 40℃ and 90%Rh, and the packaging material was stored in the thermohygrostat for an appropriate period of time of 48 hours or more. After a certain period of time (this period is called the retention time in the thermohygrostat), the packaging material was removed from the thermohygrostat, and the temperature and dew point inside the packaging material and the post-test weight of the desiccant were immediately measured. If the weight of the desiccant after the test exceeds 130% of the weight of the desiccant enclosed, the time of keeping it in the thermo-hygrostat should be shortened or the amount of desiccant should be increased, and the measurement should be repeated. In addition, the absolute humidity (g / m2) before and after the test should be calculated from the temperature and dew point measured before and after the test. 3 Specifically, the temperature and dew point were entered into the VAISALA Humidity Calculator to determine the absolute humidity. Measurements were performed three times for each sample, and the water vapor transmission rate was calculated using the following formula, with the average value being the water vapor transmission rate of the packaging material. Change in water vapor content 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 )}×Inner volume of packaging material (m 3 ) Water vapor permeability (g / (m 2 × 24hr) = {Weight of moisture absorbent after test (g) - Weight of moisture absorbent enclosed (g) + Change in amount of water vapor in the internal gas (g)} / {External surface area of ​​packaging material (m 2 )×{Holding time in constant temperature and humidity device (hr) / 24(hr)}}

[0114] Measurement method C: Core tube FIG. 2 is a schematic diagram for explaining the method of measuring water vapor permeability. As shown in FIG. 2, for the core tube, a film 13 with a known water vapor permeability is wrapped around the outer surface of the core tube 11, dry air with a dew point of -30°C dp is enclosed inside between the film and the core tube, 800g of a moisture absorbent 16 of JIS Z 0701 (packaging desiccant) Class A or a quality equivalent thereto or higher is placed, and the joint 15 between the film and the core tube is sealed with tape to form a glass cloth package 10. If 800g of moisture absorbent cannot be placed, the weight of the enclosed moisture absorbent is measured so that it can be known, and the moisture absorbent is enclosed so that the volume is more than half the volume of the packaging material. After that, the moisture vapor permeability of the packaging material was calculated in the same manner as in <Measuring method of water vapor permeability of packaging material: Measurement method B>. After that, the moisture vapor permeability of the core tube was calculated using the following formula based on the moisture vapor permeability of the film wrapped around the outer surface of the core tube and its surface area. Water vapor permeability of packaging material (g / (m 2 × 24hr)) = {Water vapor permeability of film (g / (m 2 × 24hr) × film surface area (m 2 ) + water vapor permeability of the core tube (g / (m 2 × 24hr) × outer diameter surface area of ​​core tube (m 2 )} / {film surface area (m 2 ) + outer diameter surface area of ​​the core tube (m 2 )}

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

[0116] The smaller the rate of change (increase) of the dielectric tangent at 10 GHz over a long period of time, the greater the effect of maintaining the storage environment of the glass cloth. The rate of change of the glass cloth over time is evaluated by the above formula, and the rate of change of the dielectric tangent of the glass cloth after 365 days from the date of starting storage of the glass cloth 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. The rate of change of the dielectric tangent of the 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 the dielectric 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 is obtained. The date of starting storage is not particularly limited, but is taken as the date on which a person skilled in the art starts storing the glass cloth in a certain environment for a certain period of time. For example, the storage start date is the date on which the glass cloth is packaged in a film and / or box-shaped packaging material after the surface treatment of the glass cloth is completed, and the storage period is the period until the packaged glass cloth is opened at the customer's process.

[0117] <Dew point change rate> The rate of change in dew point inside a package having a moisture absorbent inside was calculated using the following formula. Dew point change rate = (storage environment dew point after 365 days of storage (℃dp) - initial dew point of storage environment (℃dp)) / (external environment average dew point of packaging material (℃dp) - storage environment dew point after 365 days of storage (℃dp)) However, if the average dew point of the external environment of the packaging material is equal to the dew point of the storage environment after 365 days of storage, it is considered to have failed (NG).

[0118] <Method of measuring surface area of ​​packaging material> The surface area of ​​the packaging material was determined by measuring the shape of the package after packaging. As shown in Figure 1 (1c), when the glass cloth is sealed from the outside 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 surface area of ​​the outer diameter side of the core tube.

[0119] Moisture absorbents and films <Types of moisture absorbents> Moisture absorbent A: Abrio (registered trademark) AW (A-type silica gel) manufactured by Toyoda Kako Co., Ltd. Moisture absorbent B: RP agent (calcined diatomaceous earth and calcium oxide) manufactured by Mitsubishi Gas Chemical Company, Inc. (MGC)

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

[0121] <Production of glass cloth> <Production of Q1035 (gray cloth)> A cloth was woven using an air jet loom with a weaving density of 66 warp threads / 25 mm and 68 weft threads / 25 mm using glass yarns with a SiO2 content of more than 99.9% by mass. The cloth was woven to a width of 1300 mm. As the warp threads, silica glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used. As the weft threads, silica glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used.

[0122] <Manufacture of L1035 (gray cloth) cloth> Glass yarns with a SiO2 composition of 53% by mass and a B2O3 composition of 23% by mass were used to weave a cloth with a weaving density of 66 warp yarns / 25 mm and 68 weft yarns / 25 mm using an air jet loom. The cloth width was 1300 mm. Glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used as the warp yarns. Glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used as the weft yarns.

[0123] Examples and Comparative Examples Example A1 The obtained Q1035 greige cloth was heated in a heating furnace at 600°C for 60 seconds to perform deoiling (thermal deoiling process). Next, a treatment liquid was prepared by dispersing 0.15 mass% of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (Dow Toray Co., Ltd.) and 0.15 mass% of 5-hexenyltrimethoxysilane (silane coupling agent B); Z6161 (Dow Toray Co., Ltd.) in pure water adjusted to pH = 3 with acetic acid. The cloth was immersed in the treatment liquid at a line tension of 200N and a line speed of 30m / min (surface treatment agent application process), squeezed with a 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 agent (fixation process). The dried cloth was sprayed with 2.0kg / cm 2 After high pressure spreading at a pressure of 100°C, the glass cloth was dried at 130°C for 1 minute (drying step) and wound up to obtain a roll-shaped glass cloth. This glass cloth was stored in a storage room where the temperature was kept at 23°C and the dew point was kept at -30°C by circulating dry air at -30°C dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0124] Example A2 The rolled glass cloth obtained in Example A1 was applied to Film A (thickness: 99 μm, water vapor permeability: 0.1 g / (m)) in an environment at a temperature of 23° C. 2 The glass cloth was then wrapped in a bag of 0.25 mm × 24 hr) and moisture absorbent A (800 g) was sealed inside. Dry air with a dew point of -20°C dp was then sealed inside to set the dew point at -20°C dp, and the opening was heat-pressed and sealed to obtain a wrapped glass cloth. The wrapped glass cloth was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp, and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0125] Example A3 The obtained Q1035 greige cloth was heated at 1000°C for 60 seconds to deoil it, but the same processing as in Example A1 was carried out to obtain a roll-shaped glass cloth. This glass cloth was then placed in a box-shaped packaging material (water vapor transmission rate 0.0 g / (m)) in an environment with a temperature of 23°C and a dew point of 12°C. 2× 24 hr). Next, moisture absorbent A (800 g) was enclosed inside the package, and the package was stored in a sealed state. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0126] Example A4 A roll-shaped glass cloth was obtained in the same manner as in Example A1, except that the obtained Q1035 greige cloth was subjected to a thermal deoiling process by heating at 370°C for 72 hours in a batch-type heating furnace, and a treatment liquid was prepared by dispersing 0.30 mass% of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow-Toray Co., Ltd.). This glass cloth was then subjected to a thermal deoiling process in an environment of a temperature of 23°C and a dew point of 12°C. The treatment liquid was prepared by dispersing 0.30 mass% of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow-Toray Co., Ltd.) in a film A (thickness: 99 μm, water vapor permeability: 0.1 g / (m 2 The glass cloth was then wrapped in a bag (2.5 mm x 24 hr) and moisture absorbent B (800 g) was enclosed inside. The opening was then heat-pressed and sealed to obtain a wrapped glass cloth. The wrapped glass cloth was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[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. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[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. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0129] Example A7 The roll-shaped glass cloth obtained in Example A1 was placed in a box-shaped packaging material (water vapor permeability 0.0 g / (m)) under an environment of a temperature of 30°C and a dew point of 24°C. 2 × 24 hr), and the inside was vacuumed for 10 3After reducing the pressure to 10 Pa, the container was sealed and stored. 3 The dew point inside the box-shaped packaging material was -32°C dp (Pa). After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0130] Example A8 The rolled glass cloth obtained in Example A1 was coated with Film B (thickness: 116 μm, water vapor permeability: 0.2 g / (m)) under an environment of a temperature of 23° C. and a dew point of 12° C. 2 The glass cloth was then wrapped in a bag of 0.25 mm × 24 hr) and moisture absorbent A (800 g) was sealed inside. Dry air with a dew point of -20°C dp was then sealed inside to set the dew point at -20°C dp, and the opening was heat-pressed and sealed to obtain a wrapped glass cloth. The wrapped glass cloth was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp, and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0131] Example A9 The rolled glass cloth obtained in Example A1 was coated with a film C (thickness 78 μm, moisture permeability 6.6 g / (m)) under an environment of a temperature of 23° C. and a dew point of 12° C. 2 The glass cloth was then wrapped in a bag (200 g x 24 hr) and moisture absorbent A (8000 g) was enclosed inside. The opening was then heat-pressed and sealed to obtain a wrapped glass cloth. The wrapped glass cloth was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[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° C. by circulating dry air at −2° C. dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0133] Example A11 The obtained Q1035 greige cloth was heated in a heating furnace at 600°C for 60 seconds, deoiled (thermal deoiling process), and wound up to obtain a rolled glass cloth. This glass cloth was stored in a storage room where the temperature was kept at 23°C and the dew point was kept at -30°C by circulating dry air at -30°Cdp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[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° C. dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0135] <Reference example A> A roll-shaped glass cloth was obtained in the same manner as in Example A1, except that the obtained L1035 greige cloth was heated at 370°C for 72 hours in a batch-type heating furnace as a thermal deoiling process. The glass cloth was stored in a storage room maintained at a temperature of 30°C and a dew point of 24°C dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[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° C. dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[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° C. dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[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° C. dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0139] Comparative Example A5 The rolled glass cloth obtained in Example A1 was heated to 300° C. in an environment with a temperature of 23° C. and a dew point of 12° C. to form a film D (thickness: 45 μm, water vapor permeability: 11 g / (m 2 The glass cloth was then wrapped in a bag (200 g x 24 hr) and moisture absorbent A (8000 g) was enclosed inside. The opening was then heat-pressed and sealed to obtain a wrapped glass cloth. The wrapped glass cloth was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[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° C. dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

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

[0142] [Table 2]

[0143] [Table 3]

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

[0145] Moisture absorbents and packaging materials <Types of moisture absorbents> Moisture absorbent A: Abrio (registered trademark) AW (A-type silica gel) manufactured by Toyoda Kako Co., Ltd. Moisture absorbent B: RP agent (calcined diatomaceous earth and calcium oxide) manufactured by Mitsubishi Gas Chemical Company, Inc. (MGC)

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

[0147] <Production of glass cloth> <Production of Q1035 (gray cloth)> A cloth was woven using an air jet loom with a weaving density of 66 warp threads / 25 mm and 68 weft threads / 25 mm using glass yarns with a SiO2 content of more than 99.9% by mass. The cloth was woven to a width of 1300 mm. As the warp threads, silica glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used. As the weft threads, silica glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used.

[0148] <Manufacture of L1035 (gray cloth) cloth> Glass yarns with a SiO2 composition of 53% by mass and a B2O3 composition of 23% by mass were used to weave a cloth with a weaving density of 66 warp yarns / 25 mm and 68 weft yarns / 25 mm using an air jet loom. The cloth width was 1300 mm. Glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used as the warp yarns. Glass yarns with an average filament diameter of 5.0 μm, 100 filaments, and 1.0Z twist were used as the weft yarns.

[0149] Examples and Comparative Examples Example B1 The obtained Q1035 greige cloth was heated in a heating furnace at 600°C for 60 seconds to perform deoiling (thermal deoiling process). Next, a treatment liquid was prepared by dispersing 0.15 mass% of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (Dow Toray Co., Ltd.) and 0.15 mass% of 5-hexenyltrimethoxysilane (silane coupling agent B); Z6161 (Dow Toray Co., Ltd.) in pure water adjusted to pH = 3 with acetic acid. The cloth was immersed in the treatment liquid at a line tension of 200N and a line speed of 30m / min (surface treatment agent application process), squeezed with a 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 agent (fixation process). The dried cloth was sprayed with 2.0kg / cm 2 After high pressure spreading, the glass cloth was dried at 130°C for 1 minute (drying step) and wound around a hollow core tube to obtain a roll of glass cloth.

[0150] This glass cloth was placed in a packaging material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m 2 × 24 hr)) and moisture absorbent 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 at -20°C dp, and the opening was heat-pressed and 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.

[0151] Example B2 The obtained Q1035 greige cloth was heated at 1000°C for 60 seconds to deoil it, and the same processing as in Example B1 was carried out to obtain a roll-shaped glass cloth. This glass cloth was then packed in a packaging material F (stainless steel box, water vapor transmission rate 0.0 g / (m)) under an environment of a temperature of 23°C and a dew point of 12°C. 2× 24 hr). Next, moisture absorbent A (800 g) was enclosed inside the packaging material and 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°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0152] Example B3 A roll of glass cloth was obtained in the same manner as in Example B1, except that the obtained Q1035 greige cloth was subjected to a thermal de-oiling process by heating at 370°C for 72 hours in a batch-type heating furnace, and a treatment liquid was prepared by dispersing 0.30 mass% of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow-Toray Industries, Inc.). This glass cloth was wrapped in packaging material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m)) in an environment of a temperature of 23°C and a dew point of 12°C. 2 × 24 hr)) and moisture absorbent B (800 g) was enclosed inside. Furthermore, the opening was heat-pressed and 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 therein. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0153] Example B4 The rolled glass cloth obtained in Example B1 was wrapped in a packaging material B (ceramic vapor deposition film, thickness 116 μm, water vapor permeability 0.2 g / (m)) in an environment at a temperature of 23° C. 2 × 24 hr)) and moisture absorbent 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 at -20°C dp, and the opening was heat-pressed and 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 rolled glass cloth obtained in Example B1 was wrapped in a packaging material C (ceramic vapor deposition film, thickness 115 μm, water vapor permeability 1.5 g / (m)) under an environment of a temperature of 23° C. and a dew point of 12° C. 2 × 24 hr), moisture absorbent A (8000 g) was enclosed inside, and the opening was heat-pressed and sealed 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°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0155] Example B6 The rolled glass cloth obtained in Example B1 was wrapped in a packaging material D (ceramic vapor deposition film, thickness 78 μm, water vapor permeability 6.6 g / (m)) under an environment of a temperature of 23° C. and a dew point of 12° C. 2 × 24 hr)) and moisture absorbent A (8000 g) was enclosed inside. Furthermore, the opening was heat-pressed and 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 therein. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0156] Example B7 The glass cloth obtained in the form of a roll in Example B1 was packed in a packaging material F (a stainless steel box with a water vapor permeability of 0.0 g / (m)) under an environment of a temperature of 30° C. and a dew point of 24° C. 2 × 24 hr), and the inside was vacuumed for 10 3 After the pressure was reduced to 10 Pa, the container was sealed and wrapped in glass cloth. 3 The dew point inside the glass cloth package was -32°C dp. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0157] Example B8 The obtained Q1035 greige cloth was heated in a heating furnace at 600°C for 60 seconds to deoil (thermal deoiling process), and wound around a hollow core tube to obtain a roll of glass cloth. This glass cloth was then wrapped in a packaging material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m)) in an environment at a temperature of 23°C. 2 × 24 hr)) and moisture absorbent 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 at -20°C dp, and the opening was heat-pressed and 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.

[0158] Comparative Example B1 The rolled glass cloth obtained in Example B1 was wrapped in a packaging material E (polyethylene film, thickness 45 μm, moisture permeability 11 g / (m)) in an environment of a temperature of 23° C. and a dew point of 12° C. 2 × 24 hr)) and moisture absorbent A (8000 g) was enclosed inside. Furthermore, the opening was heat-pressed and 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 therein. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0159] <Reference example B> A roll-shaped glass cloth was obtained in the same manner as in Example B1, except that the obtained L1035 greige cloth was heated at 370°C for 72 hours in a batch-type heating furnace as a thermal deoiling process. This glass cloth was then wrapped in a packaging material E (polyethylene film, thickness 45 μm, moisture permeability 11 g / (m)) in an environment of a temperature of 23°C and a dew point of 12°C. 2 × 24 hr)) and moisture absorbent A (8000 g) was enclosed inside. Furthermore, the opening was heat-pressed and 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 therein. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0160] <Comparative example B2> The roll-shaped glass cloth obtained in Example B2 was packed in a packaging material G (cardboard box, water vapor permeability 50 g / (m)) under an environment of a temperature of 23°C and a dew point of 12°C. 2 × 24 hr). Next, moisture absorbent A (8000 g) was enclosed inside the package and 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°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0161] Comparative Example B3 The rolled glass cloth obtained in Example B3 was packed in a packaging material G (cardboard box, water vapor permeability 50 g / (m)) under an environment of a temperature of 23°C and a dew point of 12°C. 2 × 24 hr)) and sealed to obtain a glass cloth package. The glass cloth package was then moved to and stored in an external environment with a temperature of 30°C and a dew point of 24°C dp. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0162] <Comparative example B4> The rolled glass cloth obtained in Example B8 was wrapped in a packaging material E (polyethylene film, thickness 45 μm, moisture permeability 11 g / (m)) in an environment of a temperature of 23° C. and a dew point of 12° C. 2 × 24 hr)) and the opening was heat-pressed and sealed 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°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

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

[0164] [Table 5]

[0165] [Table 6]

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

[0167] <Types of core tubes> [Table 7]

[0168] Example B9 The rolled glass cloth obtained in Example B1 was wrapped in a packaging material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m)) wider than the width of the roll in an environment at a temperature of 23° C. 2 × 24 hr)) and moisture absorbent A (800 g) was enclosed inside. Dry air with a dew point of -20°C dp was enclosed inside packaging material A to maintain the dew point at -20°C dp, and the opening was heat-pressed and sealed. The remaining packaging material on one side was pushed into the hollow part of the core tube to obtain a glass cloth package having a recess extending from one end of the core tube to the inside of the hollow part. The surface area of ​​packaging material A was 3.5 m 2 The volume of the space inside the package was 20% of the volume of the hollow part of the core tube. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0169] Example B10 The rolled glass cloth obtained in Example B1 was wrapped in a packaging material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m)) at a temperature of 23° C. 2× 24 hr)) and moisture absorbent A (800 g) was enclosed inside. Tube-shaped packaging material A was inserted into the inside of the core tube around which the roll-shaped glass cloth was wound, so as to fit along the inner wall. Dry air with a dew point of -20°C dp was enclosed inside packaging material A covering the outer surface of the roll to keep the dew point at -20°C dp. 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 to seal the opening, obtaining a ring-shaped glass cloth package with the hollow part penetrated by the outside environment. At this time, the surface area of ​​packaging material A was 3.0 m 2 The volume of the space inside the package was 5% of the volume of the hollow part of the core tube. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0170] Example B11 The obtained glass cloth was subjected to a test using a 300-m2 PET bottle with a water vapor permeability of 0.1 g / (m 2 A roll of glass cloth was obtained in the same manner as in Example B1, except that the glass cloth was wound around an FRP core tube H of 100 mm × 24 hr. The roll of glass cloth was wrapped in a packaging material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m 2 × 24 hr)) and moisture absorbent A (800 g) was enclosed inside. Dry air with a dew point of -20°C dp was enclosed inside packaging material A to maintain the dew point at -20°C dp. The film at the opening was attached to the exposed outer surface of the core tube with moisture-proof airtight tape and sealed to obtain a glass cloth package. At this time, the surface area of ​​packaging material A was 2.0 m 2 The outer surface area of ​​the core tube is 1.0 m 2 The volume of the space inside the package was 0% of the volume of the hollow part of the core tube. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0171] Example B12 The obtained glass cloth was subjected to a test for determining whether the water vapor permeability was 1.0 g / (m 2A roll of glass cloth was obtained in the same manner as in Example B1, except that the glass cloth was wound around an FRP core tube I of 100 mm diameter x 24 hr. The roll of glass cloth was wrapped in a packaging material A (aluminum laminate film, thickness 99 μm, water vapor permeability 0.1 g / (m 2 × 24 hr)) and moisture absorbent A (1200 g) was enclosed inside. Dry air with a dew point of -20°C dp was enclosed inside packaging material A to maintain the dew point at -20°C dp. The film at the opening was attached to the exposed outer surface of the core tube with moisture-proof airtight tape and sealed to obtain a glass cloth package. At this time, the surface area of ​​packaging material A was 2.0 m 2 The outer surface area of ​​the core tube is 1.0 m 2 The volume of the space inside the package was 0% of the volume of the hollow part of the core tube. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0172] Comparative Example B5 The obtained glass cloth had a water vapor permeability of 9.6 g / (m 2 A roll of glass cloth was obtained in the same manner as in Example B1, except that the glass cloth was wound around a paper core tube J having a length of 1.0 × 24 hr. This roll of glass cloth was wrapped in a packaging material E (polyethylene film, thickness 45 μm, moisture permeability 11 g / (m)) under an environment of a temperature of 23° C. and a dew point of 12° C. dp. 2 × 24 hr)) and encapsulated moisture absorbent A (8000 g) inside. The film at the opening was attached to the core tube with moisture-proof airtight tape and sealed to obtain a glass cloth package. At this time, the surface area of ​​the packaging material E was 1.8 m 2 The outer surface area of ​​the core tube is 0.8m 2 The volume of the space inside the package was 0% of the volume of the hollow part of the core tube. The glass cloth package was then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp and stored there. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0173] The production 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 tangent of the glass cloth after long-term storage (after 30 days and 365 days) did not change, whereas in Comparative Example B5, the dielectric 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 Moisture absorbent

Claims

1. A method for storing glass cloth, comprising: The glass cloth is configured with glass yarns including a plurality of filaments as warp yarns and weft yarns, and the silicon (Si) content in the glass yarns is 95.0% by mass to 100% by mass in terms of silicon dioxide (SiO 2 ); 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 having an average dew point of 10°C dp or less and an average temperature of 100°C or less under atmospheric pressure in a storage environment, The method for storing glass cloth, wherein the atmosphere is reduced to a pressure lower than atmospheric pressure.

2. A method for storing glass cloth, comprising: The glass cloth is configured with glass yarns including a plurality of filaments as warp yarns and weft yarns, and the silicon (Si) content in the glass yarns is 95.0% by mass to 100% by mass in terms of silicon dioxide (SiO 2 ); 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 wrapped in a film-like packaging material, and the film-like packaging material has a thickness of 50 μm or more; The method includes storing the glass cloth in an atmosphere having an average dew point of 10°C dp or less and an average temperature of 100°C or less under the atmospheric pressure of the storage environment. How to store glass 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 represented by the following formula (1): X (R) ３－ｎ Yes ｎ ・・・(1) (In formula (1), X represents an organic functional group having at least one of an amino group and an unsaturated double bond group having radical reactivity; each Y represents an alkoxy group; n represents an integer of 1 to 3; and each R represents independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.) The method of claim 3, comprising a silane coupling agent represented by the formula:

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

6. The method according to claim 3 , wherein the surface treatment agent comprises two or more silane coupling agents having 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 storing; and opening the surface-treated glass cloth.

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

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

10. 3. The method according to claim 1, further comprising the step of heating the glass cloth at a temperature of 600° C. or higher while transporting the glass cloth in a roll-to-roll manner before storing the glass cloth.

11. The method according to claim 1 , wherein the glass cloth is stored as a package 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 wrapped in a film-like packaging material, and the film-like packaging material has a thickness of 50 μm or more.

13. The method according to claim 2 or 11, wherein the glass cloth is stored as a package 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 in a roll state wound around a hollow cylindrical core tube and wrapped in a film-like packaging material, and the film-like packaging material has a recess extending from one or both ends of the core tube into the hollow portion, or is annular and passes through the hollow portion of the core tube.

15. The method according to claim 14, wherein the volume ratio of the space inside the film-like packaging material 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.

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 package 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 permeability of the core tube measured under conditions of 40°C and 90% Rh is 8 g / (m ２ 15. The method of claim 14, wherein the heating time is 24 hours or less.

19. The packaging material has a water vapor permeability of 8 g / (m ２ 12. The method according to claim 2 or 11, wherein the heating time is 24 hours or less.

20. 12. The method of claim 2 or 11, wherein the package is configured to dehumidify to maintain an average dew point within the package at or below 10°C dp.

21. The method according to claim 1 or 2, comprising storing the product at an average dew point under atmospheric pressure in the storage environment of -21°C dp or less.

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

23. The amount of the moisture absorbent enclosed is expressed by the following formula (2): WVTR [g / (m ２ x24hr)] x package surface area [m ２ ] / Amount of enclosed moisture absorbent [g]≦0.0030 ... (2) The method according to claim 22, wherein WVTR satisfies the formula (2), where 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. 23. The method of claim 22, wherein the moisture absorbent 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. 23. The method of claim 22, wherein the moisture absorbent is a sheet-type moisture absorbent.

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

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

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

29. The weight per unit area of ​​the glass cloth (mass of the glass cloth) is 8 to 25 g / m ２ The method according to claim 1 or 2, wherein the range is

30. A glass cloth package including a packaging material and a glass cloth contained inside the packaging material, The glass cloth is configured with glass yarns containing a plurality of filaments as warp and weft yarns, The silicon (Si) content in the glass yarn is 95.0% by mass to 100% by mass in terms of silicon dioxide (SiO 2 ), The dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less, the packaging is sealed; The glass cloth is in a roll state, The water vapor permeability of the packaging material measured under conditions of 40°C and 90% Rh is 8 g / (m ２ × 24 hr) or less, and the dew point inside the packaging material is 10 ° C. dp or less, The glass cloth packaging body, wherein the inside of the packaging material is decompressed to a pressure lower than atmospheric pressure.

31. A glass cloth package comprising a packaging material and a glass cloth contained inside the packaging material, The glass cloth is configured with glass yarns containing a plurality of filaments as warp and weft yarns, The silicon (Si) content in the glass yarn is 95.0% by mass to 100% by mass in terms of silicon dioxide (SiO 2 ), The dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less, the packaging is sealed; The glass cloth is in a roll state, The packaging material has a water vapor transmission rate of 8 g / (m 2 × 24 hr) or less as measured under conditions of 40°C and 90% Rh, and a dew point inside the packaging material is 10°C dp or less, The glass cloth packaging body, wherein the packaging material is a film and the thickness of the film is 50 μm or more.

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

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

35. 32. The glass cloth packaging according to claim 30 or 31, wherein the glass cloth is wrapped in a film in a roll state around a hollow columnar core tube, and the film has a recess extending from one or both ends of the core tube into the hollow portion, or is annular and passes through the hollow portion of the core tube.

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

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

38. 36. The glass cloth package according to claim 35, 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 conditions of 40°C and 90% Rh is 8 g / (m ２ The glass cloth packaging according to claim 35, wherein the glass cloth packaging has a durability of 300% or less.

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 package according to claim 30 or 31, wherein a moisture absorbent is enclosed inside the packaging material.

42. The amount of the moisture absorbent enclosed is expressed by the following formula (2): WVTR [g / (m ２ x24hr)] x package surface area [m ２ ] / Amount of enclosed moisture absorbent [g]≦0.0030 ... (2) 42. The glass cloth packaging according to claim 41, wherein WVTR satisfies the formula (2), where 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. 42. The glass cloth packaging according to claim 41, wherein the moisture absorbent 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 moisture absorbent is in sheet form.

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

46. The glass cloth package according to claim 31, wherein the interior of the packaging material is at a pressure 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 represented by the following formula (1): X (R) ３－ｎ Yes ｎ ・・・(1) (In formula (1), X represents an organic functional group having at least one of an amino group and an unsaturated double bond group having radical reactivity; each Y represents an alkoxy group; n represents an integer of 1 to 3; and each R represents 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 represented by the formula:

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

50. The glass cloth packaging according to claim 47, wherein the surface treatment agent comprises two or more silane coupling agents having 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 pitch density of the warp and / or weft of the glass cloth is in the range of 66 to 120 threads / inch (= 66 to 120 threads / 25 mm).

53. The weight per unit area of ​​the glass cloth (mass of the glass cloth) is 8 to 25 g / m ２ The glass cloth packaging according to claim 30 or 31, wherein the thickness is in the range of

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