Glass cloth storage method and glass cloth package

Abstract

According to the present disclosure, a method for storing a glass cloth and a glass cloth package are provided, whereby it is possible to maintain the dielectric properties of a glass cloth having excellent dielectric properties. The glass cloth is configured from glass filaments including a plurality of filaments as warp and weft, and the dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less. The storage method includes storing the glass cloth in an atmosphere having an average dew point of 18 DEG C dp or less and an average temperature of 100 DEG C or less at the atmospheric pressure of the storage environment. The packaging body includes a packaging material and a glass cloth housed inside the packaging material, and the water vapor transmission rate of the packaging material measured under the condition of 40 DEG C and 90% Rh is 8 g / (m < 2 > * 24 hr) or less.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a glass cloth storage method 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 into this international application. BACKGROUND

[0002] Currently, high performance of information terminals such as smartphones and high speed communication typified by 5G communication is developing. In this background, for example, for a printed circuit board for high speed communication, not only improvement of heat resistance is expected, but also further improvement of dielectric properties (for example, low dielectric loss tangent) of an insulating material thereof is expected. Similarly, for a prepreg used in an insulating material of a printed circuit board, and a glass filament and a glass cloth contained in the prepreg, improvement of dielectric properties is also expected.

[0003] As a method of improving dielectric properties, for example, a method of producing a prepreg using a low dielectric glass is known (refer to Patent Documents 1 and 2). More specifically, Patent Document 1 describes producing a prepreg using a glass filament having a silicon dioxide (SiO2) composition amount of 98 mass% or more and 100 mass% or less. Patent Document 2 describes performing heat treatment on a quartz glass cloth for the purpose of further low dielectric loss tangent.

[0004] Patent Document 3 describes that the activity of Si-OH group on the surface of quartz glass is strong, and in particular, under a high temperature atmosphere, water is absorbed by hydrogen bonding, and the Si-O-Si bond is broken, thereby further generating Si-OH group (SiO2+ H2O Si-OH), and the generated Si-OH group deteriorates the dielectric loss tangent of the glass cloth (paragraph 0006). Therefore, for the purpose of re-bonding the Si-OH group to form a Si-O-Si bond and low dielectric loss tangent of the glass cloth, it is described that when performing heat treatment on a quartz glass cloth, in a vacuum or a gas having a dew point of 15°C or lower, at a maximum heating temperature of 100°C to 600°C, and under a condition that the heating amount represented by heating temperature (°C) x heating time (h) at 100°C or higher is 450 (°C·h) or more (claim 1 or the like).

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-127747

[0008] Patent Document 2: Japanese Patent Application Publication No. 2021-63320

[0009] Patent Literature 3: Japanese Patent No. 7269416 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] Patent Literature 3 describes SiO2+ H2O The reaction of Si-OH is not activated at a temperature lower than 100°C (paragraph 0025). Thus, it has been conventionally considered that water has no influence on the dielectric loss tangent of glass cloth in a temperature region lower than 100°C. In this regard, the present inventors have first found that even if the dielectric loss tangent at the time of manufacturing of glass cloth is reduced by means disclosed in Patent Literatures 1 to 3, generation of silanol groups based on the above-described equilibrium reaction proceeds in an environment lower than 100°C at the time of long-term storage of the glass cloth, and the dielectric loss tangent of the glass cloth increases.

[0012] Therefore, one of the objects of the present disclosure is to provide a storage method of glass cloth and a glass cloth package that can maintain the dielectric properties of glass cloth having excellent dielectric properties.

[0013] SOLUTION TO PROBLEM

[0014] Some of the embodiments of the present disclosure are exemplified in the following items [1] to

[57] . [1]

[0016] A storage method of glass cloth, wherein the glass cloth is constituted with glass filaments each including a plurality of filaments as warp and weft, and the dielectric loss tangent of the glass cloth at 10 GHz is 0.00200 or less,

[0017] The method includes storing the glass cloth in an atmosphere having an average dew point of 18°Cdp or less and an average temperature of 100°C or less at the atmospheric pressure of the storage environment. [2]

[0019] The method according to item 1, wherein the content of silicon (Si) in the glass filaments is 95.0 mass% to 100 mass% in terms of silicon dioxide (SiO2). [3]

[0021] The method according to item 1 or 2, wherein the glass cloth has a surface treatment agent including a silane coupling agent on the surface thereof. [4]

[0023] The method according to item 3, wherein the surface treatment agent includes a silane coupling agent represented by the following formula (1):

[0024] X(R)3-n SiY n …(1)

[0025] (In formula (1), X is an organic functional group containing at least one of an amino group and an unsaturated double bond group having radical reactivity, Y is each independently an alkoxy group, n is an integer of 1 or more and 3 or less, and R is each independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group). [5]

[0027] The method according to any one of items 4, wherein the surface treatment agent contains two or more silane coupling agents different in X in the above formula (1). [6]

[0029] The method according to any one of items 3 to 5, wherein the surface treatment agent contains two or more silane coupling agents different in molecular weight. [7]

[0031] The method according to any one of items 3 to 6, wherein the method further comprises, before the storage, a step of surface-treating the glass cloth with a surface treatment agent containing a silane coupling agent, and a step of opening the glass cloth subjected to the surface treatment. [8]

[0033] The method according to any one of items 1 to 7, wherein the glass cloth has a dielectric loss tangent at 10 GHz of 0.00051 or more and 0.00200 or less. [9]

[0035] The method according to any one of items 1 to 8, wherein the glass cloth has a beat-in density of warp and / or weft threads in the range of 66 to 120 threads / inch (= 66 to 120 threads / 25 mm).

[10]

[0037] The method according to any one of items 1 to 9, wherein the method further comprises, before the storage, a step of heating the glass cloth at a temperature of 600°C or higher while transporting the glass cloth in a roll-to-roll (R2R) manner.

[11]

[0039] The method according to any one of items 1 to 10, wherein the glass cloth is stored in the form of a package in which the glass cloth is wrapped with a packaging material in the form of a box and / or a film.

[12]

[0041] The method according to item 11, wherein the glass cloth is stored in a form of a package in which the glass cloth is wrapped with a film-like packaging material, and the film-like packaging material has a thickness of 50 μm or more.

[13]

[0043] The method according to item 11 or 12, wherein the glass cloth is stored in a form of a package in which the glass cloth is wrapped with a film-like packaging material, and the film-like packaging material is an aluminum laminated film.

[14]

[0045] The method according to any one of items 11 to 13, wherein the glass cloth is stored in a form of a package in which the glass cloth is wrapped with a film-like packaging material in a state of being wound around a core pipe of a hollow column shape, and the film-like packaging material has a recess portion extending into the hollow portion from one end or both ends of the core pipe, or the film-like packaging material is a circular ring shape that penetrates the hollow portion of the core pipe.

[15]

[0047] The method according to item 14, wherein a ratio of a volume of a space that becomes an inside of the film-like packaging material to a volume of the hollow portion of the core pipe is 50% or less of the volume of the hollow portion of the core pipe.

[16]

[0049] The method according to item 14 or 15, wherein the film-like packaging material is a circular ring shape that penetrates the hollow portion of the core pipe.

[17]

[0051] The method according to item 14 or 15, wherein the package is configured such that the glass cloth is sealed from an external environment by the film-like packaging material and the core pipe.

[18]

[0053] The method according to any one of items 14 to 17, wherein a water vapor permeability of the core pipe measured at 40°C under 90% Rh is 8 g / (m 2 × 24 hr) or less.

[19]

[0055] The method according to any one of items 11 to 18, wherein a water vapor permeability of the packaging material measured at a measurement temperature of 40°C and a measurement humidity of 90% Rh is 8 g / (m 2 × 24 hr) or less.

[20]

[0057] The method according to any one of items 11 to 19, wherein the package is configured such that the inside is dehumidified in a manner that an average dew point thereof is maintained at 18°C dp or less.

[21]

[0059] The method according to any one of items 1 to 20, which comprises storage under conditions where the average dew point under the air pressure of the above storage environment is 13°Cdp or more and 18°Cdp or less.

[22]

[0061] The method according to any one of items 1 to 20, which comprises storage under conditions where the average dew point under the air pressure of the above storage environment is -21°Cdp or less.

[23]

[0063] The method according to any one of items 11 to 19, wherein a moisture absorbent is contained in the above packaging body.

[24]

[0065] The method according to item 23, wherein the amount of the moisture absorbent contained satisfies the following formula (2):

[0066] WVTR [g / (m 2 × 24 hr)] × packaging body surface area [m 2 ] / amount of moisture absorbent [g] ≤ 0.0030 … (2)

[0067] (In formula (2), WVTR is the water vapor transmission rate of the packaging material under a measurement temperature of 40°C and a measurement humidity of 90% Rh.).

[25]

[0069] 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 desiccant, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate.

[26]

[0071] The method according to any one of items 23 to 25, wherein the moisture absorbent is a sheet-shaped moisture absorbent.

[27]

[0073] The method according to any one of items 1 to 26, wherein the atmosphere is dry air having an average dew point of 18°Cdp or less, or a gas containing at least one selected from the group consisting of nitrogen, argon, and oxygen, having an average dew point of 18°Cdp or less.

[28]

[0075] The method according to any one of items 1 to 27, wherein the atmosphere is reduced to less than atmospheric pressure.

[29]

[0077] The method according to any one of items 1 to 28, wherein the glass cloth is stored in a storage room in which a dew point and a temperature are controlled.

[30]

[0079] The method according to any one of items 1 to 29, wherein a weight per unit area (mass of the glass cloth) of the glass cloth is in a range of 8 to 25 g / m 2 .

[31]

[0081] A glass cloth packaging body comprising: a packaging material, and a glass cloth housed inside the packaging material,

[0082] The glass cloth is constituted with glass filaments including a plurality of filaments as warp and weft,

[0083] A tangent of a dielectric loss angle of the glass cloth at 10 GHz is 0.00200 or less,

[0084] The packaging material is sealed,

[0085] A water vapor permeability of the packaging material measured at 40°C under 90% Rh is 8 g / (m 2 × 24 hr) or less.

[32]

[0087] The glass cloth packaging body according to item 31, wherein the packaging material is a box and / or a film.

[33]

[0089] The glass cloth packaging body according to item 32, wherein the packaging material is a film, and a thickness of the film is 50 μm or more.

[34]

[0091] The glass cloth packaging body according to item 32 or 33, wherein the packaging material is a film, and the film is an aluminum laminated film.

[35]

[0093] The glass cloth packaging body according to any one of items 32 to 34, wherein the glass cloth is packaged with a film in a state of being wound in a roll around a hollow columnar core pipe, the film has a recess portion extending into a hollow portion from one end or both ends of the core pipe, or the film is a circular ring shape that penetrates the hollow portion of the core pipe.

[36]

[0095] The glass cloth packaging body according to item 35, wherein a proportion of a space that becomes an inside of the film in a hollow portion volume of the core pipe is 50% or less of the hollow portion volume of the core pipe.

[37]

[0097] The glass cloth packaging body according to any one of items 35 to 38, wherein the film is a ring shape that penetrates the hollow portion of the core tube.

[38]

[0099] The glass cloth packaging body according to item 35 or 36, wherein the packaging body is configured such that the glass cloth is sealed from the outside environment by the film and the core tube.

[39]

[0101] The glass cloth packaging body according to any one of items 35 to 38, wherein the water vapor transmission rate of the core tube, measured at 40°C and 90% Rh, is 8 g / (m 2 × 24 hr) or less.

[40]

[0103] The glass cloth packaging body according to any one of items 31 to 39, wherein the dew point inside the packaging material is 18°C dp or less.

[41]

[0105] The glass cloth packaging body 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]

[0107] The glass cloth packaging body according to any one of items 31 to 39, wherein the dew point inside the packaging material is -21°C dp or less.

[43]

[0109] The glass cloth packaging body according to any one of items 31 to 42, wherein the glass cloth is in a roll state.

[44]

[0111] The glass cloth packaging body according to any one of items 31 to 43, wherein a moisture absorbent is enclosed inside the packaging material.

[45]

[0113] The glass cloth packaging body according to item 44, wherein the enclosed amount of the moisture absorbent satisfies the following formula (2):

[0114] WVTR [g / (m 2 × 24 hr)] × packaging body surface area [m 2 ] / enclosed amount of moisture absorbent [g] ≤ 0.0030 … (2)

[0115] (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]

[0117] The glass cloth packaging body according to any one of items 44 to 46, wherein the hygroscopic agent is 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.

[47]

[0119] The glass cloth packaging body according to any one of items 44 to 46, wherein the hygroscopic agent is 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.

[48]

[0121] The glass cloth packaging body 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 containing at least one selected from the group consisting of nitrogen, argon, and oxygen, having a dew point of 18°C dp or less.

[49]

[0123] The glass cloth packaging body according to any one of items 31 to 48, wherein the inside of the packaging material is a pressure lower than atmospheric pressure.

[50]

[0125] The glass cloth packaging body according to any one of items 31 to 49, wherein the content of silicon (Si) in the glass filaments is 95.0 to 100 mass% as silicon dioxide (Si02).

[51]

[0127] The glass cloth packaging body 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]

[0129] The glass cloth packaging body according to item 51, wherein the surface treatment agent contains the silane coupling agent represented by the following formula (1):

[0130] X(R) 3-n SiY n …(1)

[0131] (In formula (1), X is an organic functional group containing at least one of an amino group and an unsaturated double bond group having radical reactivity, Y is each independently an alkoxy group, n is an integer of 1 or more and 3 or less, and R is each independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group).

[53]

[0133] The glass cloth packaging body according to item 52, wherein the surface treatment agent contains two or more silane coupling agents different in X in the above formula (1).

[54]

[0135] The glass cloth packaging body 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]

[0137] The glass cloth packaging body according to any one of items 31 to 54, wherein the dielectric loss tangent of the glass cloth at 10 GHz is 0.00051 or more and 0.00200 or less.

[56]

[0139] The glass cloth packaging body according to any one of items 31 to 55, wherein the beat-in density of the warp and / or weft yarns of the glass cloth is in the range of 66 to 120 threads / inch (= 66 to 120 threads / 25 mm).

[57]

[0141] The glass cloth packaging body according to any one of items 31 to 56, wherein the weight per unit area (mass of the glass cloth) of the glass cloth is in the range of 8 to 25 g / m 2 .

[0142] Effects of the Invention

[0143] According to the present disclosure, it is possible to provide a storage method of a glass cloth capable of maintaining the dielectric properties of the glass cloth having excellent dielectric properties and a glass cloth packaging body. BRIEF DESCRIPTION OF DRAWINGS

[0144] [ Figure 1 ] Figure 1 is a schematic view showing a core tube axial direction cross section of the glass cloth packaging body of the present disclosure.

[0145] [ Figure 2 ] Figure 2 is a schematic view for explaining a measurement method of the water vapor permeability of the core tube. DETAILED DESCRIPTION

[0146] 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 can be made within the scope of the gist thereof. In the present embodiment, a numerical range recited using "~" includes the numerical values before and after "~" as lower limit values and upper limit values. In the present embodiment, in a numerical range recited in stages, the upper limit value or the lower limit value recited in a certain numerical range can be replaced with the upper limit value or the lower limit value of the other numerical range recited in stages. In the present embodiment, the upper limit value or the lower limit value recited in a certain numerical range can also be replaced with the value shown in the examples. In the present embodiment, the term "process" includes not only an independent process, but also a process included in the term as long as the function of the process is achieved, in a case where the process cannot be clearly distinguished from other processes.

[0147] Method for storing glass cloth

[0148] The method for storing glass cloth of the present disclosure relates to a method for storing glass cloth constituted with glass yarns including a plurality of filaments as warp yarns and weft yarns, and having a dielectric loss tangent of 0.00200 or less at 10 GHz. Moreover, the method of the present disclosure includes storing the above glass cloth under an atmosphere having an average dew point of 18°Cdp or less and an average temperature of 100°C or less at the atmospheric pressure of the storage environment. It has been conventionally considered that the reaction in which Si-O-Si bonds are cleaved by moisture to produce Si-OH groups is not activated in the temperature region lower than 100°C, and thus no particular consideration has been given to the method for storing glass cloth, and the dielectric loss tangent sometimes increases over time. In this regard, by using the method of the present disclosure, the cleavage of Si-O-Si bonds by moisture in the storage environment to produce Si-OH groups can be suppressed, and thus the increase in the dielectric loss tangent of the glass cloth over time can be suppressed. Note that, in the present disclosure, "suppressing" does not mean that the dielectric loss tangent does not increase at all, but only that the increase in the dielectric loss tangent is suppressed to some extent.

[0149] <Glass cloth>

[0150] Glass cloth has a structure in which glass yarns including a plurality of glass filaments are woven as warp yarns and weft yarns. The weaving structure of the glass cloth can include plain weave, basket weave, satin weave, twill weave, and the like. Among them, the plain weave structure is preferable.

[0151] The insertion density of the warp yarns and the weft yarns that constitute the glass cloth is each independently preferably 10 to 120 strands / inch (= 10 to 120 strands / 25 mm). The lower limit value of the insertion density is more preferably 20 strands / inch or more, 30 strands / inch or more, 40 strands / inch or more, 50 strands / inch or more, 60 strands / inch or more, or 66 strands / inch or more. The upper limit value of the insertion density is more preferably 110 strands / inch or less or 100 strands / inch or less. When the insertion density is within the above range, it is easy to obtain a glass cloth of a preferred thickness. The insertion density of the warp yarns and the weft yarns can be different.

[0152] The weight per unit area of the glass cloth (the mass of the glass cloth) is preferably 8 to 250 g / m 2 , more preferably 8 to 100 g / m 2 , further preferably 8 to 80 g / m 2 , more further preferably 8 to 50 g / m 2 , particularly preferably 8 to 25 g / m 2 , or 8 to 23.2 g / m 2 . When the weight per unit area of the glass cloth is within the above range, it is easy to obtain a glass cloth of a preferred thickness.

[0153] The thickness of the glass cloth is preferably more than 0 and 60 μm or less. The upper limit value of the thickness of the glass cloth is more preferably 55 μm or less, further preferably 50 μm or less. When the thickness of the glass cloth is within the above range, it is easy to obtain a glass cloth that is suitable as an insulating material. The lower limit value of the thickness of the glass cloth is more preferably 5 μm or more, or 10 μm or more.

[0154] <Dielectric Loss Tangent of Glass Cloth>

[0155] The dielectric loss tangent of the glass cloth at 10 GHz, which is measured by the method described in the Examples, is 0.00200 or less. In such a glass cloth, the dielectric loss tangent of the glass cloth increases over time due to the influence of water in the storage environment even at a temperature of 100°C or lower, and therefore by setting the average dew point temperature of the storage environment of the glass cloth to 18°C dp or less, it is possible to suppress the increase in the dielectric loss tangent of the glass cloth. Note that the "storage environment" here refers to the atmosphere (gas) that the glass cloth directly contacts.

[0156] 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, further preferably 0.00090 or less, still further 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 setting the dielectric loss tangent of the glass cloth within the above range, the glass cloth is easily affected by moisture around the glass cloth in the storage environment of the glass cloth, and thus it is easy to obtain an effect of suppressing an increase in the dielectric loss tangent.

[0157] <Glass filament>

[0158] The glass filament constituting the glass cloth is preferably obtained using a low-dielectric glass as a raw material. The Si content of the low-dielectric glass filament is more preferably 95.0 mass% or more and 100 mass% or less, calculated as SiO2. By using such a glass filament, it is possible to achieve an improvement in the dielectric properties of the obtained glass cloth. In addition, in such a glass filament, an increase in the dielectric loss tangent of the glass cloth over time is significantly noticeable, and thus it is easy to obtain an effect of suppressing an increase in the dielectric loss tangent. From the viewpoint of improving the dielectric properties, the Si content is preferably 99.0 mass% or more, more preferably 99.5 mass% or more, and further preferably 99.9 mass% or more.

[0159] The average filament diameter of the glass filament constituting the glass filament 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, further preferably 3.5 μm or more and 7.0 μm or less, still further 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 the above lower limit value or more, it is easy to ensure the breaking strength of the filament, and thus the obtained glass cloth is less likely to generate fluff. In addition, when the filament diameter is less than the above upper limit value, it is possible to prevent the mass of the glass cloth from becoming too large, and thus it is easy to perform transportation or processing.

[0160] <Silane coupling agent>

[0161] The glass cloth preferably has a surface treatment agent containing a silane coupling agent on its surface. More specifically, the glass filament (including the glass filament) constituting the glass cloth is preferably subjected to surface treatment by a surface treatment agent containing a silane coupling agent. By providing the glass cloth with a surface treatment agent, there is a tendency that the reactivity with the matrix resin is improved. In addition, since it is less likely to be affected by moisture during storage, it is possible to more effectively suppress an increase in the dielectric loss tangent over time.

[0162] As the silane coupling agent, for example, a silane coupling agent represented by the following formula (1) is preferably used:

[0163] X(R) 3-n SiY n …(1)

[0164] {In formula (1), X is an organic functional group containing at least one of a carbon-carbon double bond having radical reactivity or the like having radical reactivity and an amino group, Y is each independently an alkoxy group, n is an integer of 1 or more and 3 or less, and R is a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.}

[0165] X in formula (1) is more preferably an organic functional group having one or more methacryloxy groups or acryloxy groups from the viewpoint of reactivity with the matrix resin.

[0166] As Y in formula (1) above, as the alkoxy group, in order to stabilize the treatment of the glass cloth, an alkoxy group having a carbon number of 1 to 5 (the carbon number is 1, 2, 3, 4, or 5) is preferable.

[0167] As the surface treatment agent, the silane coupling agent represented by formula (1) can be used alone, or two or more silane coupling agents different in X in formula (1) can be used in combination. In addition, as the silane coupling agent represented by formula (1), for example, a single substance such as vinyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 5-hexenyltrimethoxysilane, or the like, or a mixture thereof can be used.

[0168] The molecular weight of the silane coupling agent is preferably 100 to 600, more preferably 150 to 500, and further preferably 200 to 450. Among them, two or more silane coupling agents different in molecular weight are particularly preferably used. By using two or more silane coupling agents different in molecular weight to treat the surface of the glass fiber, there is a tendency that the density of the treatment agent on the surface of the glass is higher, and the reactivity with the matrix resin is easily further improved.

[0169] From the viewpoint that the reactivity with the resin is not easily hindered, the silane coupling agent is preferably nonionic. Among the nonionic silane coupling agents, a silane coupling agent having at least one group selected from the group consisting of a vinyl group, a methacryloxy group, and an acryloxy group is preferable, and a silane coupling agent having at least one methacryloxy group or acryloxy group is particularly preferable. By not hindering the reactivity with the resin, the heat resistance and reliability of the printed circuit board can be improved.

[0170] <Loss on ignition value>

[0171] The ignition loss value of the glass cloth is preferably 0.01 mass% or more and less than 2.0 mass%, more preferably 0.01 mass% or more and less than 1.5 mass%, further preferably 0.02 mass% or more and less than 1.0 mass%, still further preferably 0.03 mass% or more and less than 0.8 mass%, particularly preferably 0.03 mass% or more and less than 0.3 mass%. When the ignition loss value is within the above range, it is easy to obtain a glass cloth that exhibits a low dielectric loss tangent. Note that the ignition loss value is measured in accordance with JIS R3420.

[0172] <Storage of the glass cloth>

[0173] The storage method of the glass cloth includes storing the glass cloth in an atmosphere having an average dew point of 18°Cdp or lower and an average temperature of 100°C or lower at the atmospheric pressure of the storage environment of the glass cloth. Note that the "storage environment" here refers to the atmosphere directly contacted by the glass cloth. By managing the storage environment of the glass cloth within the above range, it is possible to suppress the temporal increase in the dielectric loss tangent of the glass cloth caused by water present in the storage environment.

[0174] The storage period of the glass cloth, i.e., the period during which the storage environment in the present disclosure is maintained, is not particularly limited, and is preferably 30 days or more and 5 years or less from the viewpoint of the time required to transport the glass cloth and the improvement in supply stability, and the like. The lower limit of the storage period is preferably 30 days or more, more preferably 90 days or more, further preferably 180 days or more, still further preferably 365 days or more, and particularly preferably 730 days or more. In addition, the upper limit of the storage period of the glass cloth is preferably 5 years or less, and more preferably 3 years or less, from the viewpoint of reduction in storage cost, and the like. If the storage period is within the above range, it is possible to sufficiently obtain the effect of maintaining the storage environment. The longer the storage period, the more significantly the effect of suppressing the increase in the dielectric loss tangent can be obtained.

[0175] <Average dew point in the storage environment of the glass cloth>

[0176] In the glass cloth storage method, the average dew point of the glass cloth under the air pressure of the storage environment is 18°C dp or lower. In addition, the average dew point refers to the average dew point during the storage period. It is preferable to control in such a manner that the dew point of the storage environment is maintained at 18°C dp or lower during the entire storage period. When the average dew point is 18°C dp or lower, the tangent of the dielectric loss angle of the glass cloth can be prevented from increasing over time. The average dew point is preferably -50°C dp or higher and 18°C dp or lower. The lower limit of the average dew point can be more preferably -40°C dp or higher, -32°C dp or higher, -30°C dp or higher, -20°C dp or higher, -10°C dp or higher, 0°C dp or higher, 10°C dp or higher, or 13°C dp or higher. The upper limit of the average dew point, which can be arbitrarily combined with the above lower limit, is more preferably 15°C dp or lower, 10°C dp or lower, 5°C dp or lower, 0°C dp or lower, -5°C dp or lower, -10°C dp or lower, -15°C dp or lower, -20°C dp or lower, or -21°C dp or lower.

[0177] In the glass cloth storage method, as long as the average dew point is 18°C dp or lower, the dew point can exceed 18°C dp in a part of the storage period. It is preferable to control in such a manner that the dew point of the storage environment is maintained at 18°C dp or lower during the entire storage period. The method of controlling the average dew point within the above range can use a known humidity control method, humidity control medium, humidity control mechanism, humidity control device. For example, (1) a hygroscopic agent can be used; (2) the surrounding atmosphere can be replaced with a gas having a predetermined moisture content (for example, dry gas); (3) the surrounding atmosphere can be dehumidified using dew condensation at low temperature; (4) the surrounding atmosphere can be made to have a predetermined moisture content by reducing the pressure; and (5) combinations thereof.

[0178] As long as the average dew point is controlled within the above range, the control of the dew point can be continuously or intermittently (periodically or aperiodically) performed in an open system or a closed system. For example, the control of (1) to (5) above can be continuously performed in a closed system (for example, within a closed packaging material (bale material)); intermittently performed in a closed system (for example, only on days when the dew point is likely to rise due to the season and / or weather); continuously controlled in an open system to change the dew point around the glass cloth; and the like. In the case where the dew point is maintained by continuous humidity control, it is preferable to use a hygroscopic agent, replacement of dry gas, a dehumidifier, or the like.

[0179] <Hygroscopic agent>

[0180] In the case where a hygroscopic agent is used in the control of the dew point, the kind of the hygroscopic agent is not limited as long as it can control the average dew point within the above range. From the viewpoint of hygroscopic force, the hygroscopic agent is preferably at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, baked diatomaceous earth, synthetic zeolite, clay-based desiccant, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate, for example. Of these, at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, and baked diatomaceous earth is preferable. In addition, from the viewpoint of the space occupied, the form of packaging (bundling), it is preferable to use a hygroscopic agent in the form of a sheet.

[0181] The amount of the hygroscopic agent used is not limited as long as it can control the average dew point within the above range, and an appropriate amount is preferably used in accordance with the hygroscopic force (hygroscopic amount and hygroscopic time) of the hygroscopic agent and the storage period, etc. With respect to the hygroscopic amount, an amount of at least sufficient is preferably used. That is, it is preferable that the maximum hygroscopic amount of the hygroscopic agent be greater than the amount of moisture in the atmosphere. Alternatively, by periodically replacing the hygroscopic agent, it is easy to maintain the storage environmental conditions of the glass cloth constant.

[0182] If the storage period becomes longer, the amount of the hygroscopic agent used becomes more important. If the amount of the hygroscopic agent is appropriate, the dew point of the storage environment is maintained during a long storage period, and it is easy to suppress the rise in the dielectric loss tangent. With respect to the dew point of the storage environment, that is, the amount of water vapor present inside the packaging body, in addition to being affected by the water vapor permeability of the packaging material and the surface area of the packaging body, it is also affected by the material of the packaging material, the external temperature, humidity of the storage environment, and the kind, shape, and amount of the hygroscopic agent, etc., and thus it is difficult to estimate and enclose an appropriate amount of hygroscopic agent from the time when storage begins to constitute the packaging body. In particular, the water vapor permeability of the packaging material varies depending on the temperature and humidity of the surrounding environment, but the degree differs depending on the material of the packaging material, which makes it even more difficult to enclose an appropriate amount of hygroscopic agent. However, by using the following formula, when manufacturing a packaging body containing a hygroscopic agent, it is possible to control the water vapor permeability of the packaging material, the surface area of the packaging body, and the amount of hygroscopic agent within a prescribed range, and it is easy to control the proportion of the change in the dew point inside the storage environment with respect to the external environment (dew point change proportion). First, the amount of water vapor that can intrude into the inside of the packaging body is represented by the water vapor permeability (WVTR) x the surface area of the packaging body x the number of days of storage. Here, based on the fact that the WVTR varies depending on the temperature and humidity of the surrounding environment, the amount of water vapor that can intrude into the inside of the packaging body can be easily represented by the following formula, where the WVTR is set to the water vapor permeability at a measurement temperature of 40°C and a measurement humidity of 90% Rh (dew point of about 38°C dp).

[0183] (WVTR [g / (m 2 x 24 hr] x packaging body surface area [m 2(WVTR [g / (m 2 × 24 hr)] × package surface area [m 2 ]) × (storage environment external dew point [°C dp] / 38) × (storage environment external temperature [°C] / 40) × storage days

[0184] Next, the maximum amount of moisture that can be removed from the inside of the package by the moisture absorbent is influenced by the type, shape, and amount of the moisture absorbent, and the like, and can be easily expressed by the following equation.

[0185] 0.26 × moisture absorbent enclosed amount [g]

[0186] At this time, it is preferable that the amount of water vapor that can intrude into the inside of the package be 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, satisfy the following equation.

[0187] (WVTR [g / (m 2 × 24 hr)] × package surface area [m 2 ]) × (storage environment external dew point [°C dp] / 38) × (storage environment external temperature [°C] / 40) × storage days ≤ 0.26 × moisture absorbent enclosed amount [g]

[0188] Further, in the above equation, when the external environment temperature is set to 30°C, the storage environment external dew point is set to 24°C dp, and the storage days are set to 180 days, it is preferable that the amount of the moisture absorbent be adjusted in a manner such that the value obtained from the following equation (2) satisfies 0.0030 or less. Thereby, an appropriate amount of the moisture absorbent can be enclosed according to the configuration of the package, and the dew point change of the storage environment can be easily controlled.

[0189] WVTR [g / (m 2 × 24 hr)] × package surface area [m 2 ] / moisture absorbent enclosed amount [g] … (2)

[0190] In the case where the package is configured from two or more packaging materials having different water vapor transmission rates, the “WVTR [g / (m 2 × 24 hr)] × package surface area [m 2 ” in equation (2) is the sum of the values obtained by calculating “WVTR [g / (m 2 × 24 hr)] × package surface area [m 2 ” for each packaging material. The value obtained from equation (2) is more preferably 0.0023 or less, further preferably 0.0012 or less, and particularly preferably 0.0005 or less. The value obtained from equation (2) can also be 0.

[0191] In the present disclosure, the dew point change ratio in a package having a moisture absorbent inside is defined by the following equation.

[0192] Dew point change ratio = (Dew point of storage environment after 365 days of storage (°C dp) - Initial dew point of storage environment (°C dp)) / (Average dew point of external environment of packaging material (°C dp) - Dew point of storage environment after 365 days of storage (°C dp))

[0193] The smaller the dew point change ratio within the packaging, the greater the control effect of the storage environment based on the packaging materials and desiccants. The dew point change ratio within the packaging is evaluated using the above formula. Preferably, the dew point change ratio within the packaging after 365 days from the start date of storage of the glass cloth is 3.0 or less, more preferably 1.0 or less, further 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 ratio can also be negative.

[0194] <Dry Gases>

[0195] When using a dry gas to control the dew point, it is preferable to use a gas with a dew point temperature of 18°C ​​dp or less. With such a dry gas, it is easy to control the atmosphere so that the average dew point of the storage environment for the glass cloth is 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 is more preferably -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 is more preferably 15°C dp or less, 10°C dp or less, 5°C dp or less, 0°C dp or less, -5°C dp or less, -10°C dp or less, -15°C dp or less, -20°C dp or less, or -21°C dp or less.

[0196] As a drying gas, dry air within the aforementioned dew point temperature range, or a gas within the aforementioned dew point temperature range containing at least one selected from the group consisting of nitrogen, argon, and oxygen, can be used. From the perspective of ease of processing, dry air is preferred.

[0197] When using a dehumidifier to control the dew point, there are no limitations on the type of dehumidifier as long as it can control the average dew point within the aforementioned range. Examples include compressor-type dehumidifiers that utilize condensation at low temperatures and desiccant-type dehumidifiers (zeolite type) that regenerate the desiccant multiple times through heat.

[0198] To suppress changes in dew point over time, it is preferable to store the glass cloth in a sealed environment. As a sealing method, it is particularly preferable to prevent moisture from flowing into the storage environment. Specific storage methods will be described later.

[0199] <Average temperature in the storage environment of the glass cloth>

[0200] The glass cloth is stored in an atmosphere where the average temperature of the storage environment of the glass cloth is 100°C or lower. If the average temperature is 100°C or lower, the dielectric loss tangent of the glass cloth can be effectively suppressed from increasing over time. The average temperature of the storage environment of the glass cloth when storing 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, further preferably 35°C or lower, still further preferably 30°C or lower, and particularly preferably 25°C or lower. The lower limit of the average temperature can be preferably 10°C or higher or 20°C or higher. It is preferable to control the temperature of the storage environment to be 100°C or lower during the entire storage period. It is preferable to control the temperature to be 40°C or lower, further preferably 35°C or lower, still further preferably 30°C or lower, and particularly preferably 30°C or lower during the entire storage period. It is preferable to control the temperature of the storage environment to be 0°C or higher, 10°C or higher, or 20°C or higher during the entire storage period.

[0201] <Pressure in the storage environment of the glass cloth>

[0202] In the case where the pressure is reduced in the control of the dew point, it is preferable to control the pressure to be reduced to less than atmospheric pressure (10 5 Pa). The method of controlling the pressure of the storage environment of the glass cloth to be reduced to less than atmospheric pressure is not limited as long as the average dew point can be controlled to the above range, and known methods of pressure reduction control, pressure reduction control media, pressure reduction control mechanisms, and pressure reduction control devices, etc. can be used, and for example, a vacuum pump can be mentioned.

[0203] The pressure can be maintained by known methods as long as the storage environment of the glass cloth is maintained to be reduced to less than atmospheric pressure. For example, the pressure can be reduced continuously or intermittently (periodically or aperiodically) to the storage environment, or the glass cloth can be sealed in a packaging material (bundling material) after the reduction of the pressure to suppress the change in the pressure, etc. The pressure around the glass cloth when storing or packaging (bundling) the glass cloth is preferably 10 4 Pa or lower, and more preferably 10 3 Pa or lower. The lower limit of the pressure is not particularly limited, and is preferably more than 0 Pa or 10 Pa or higher.

[0204] <Storage method>

[0205] As the storage method of the glass cloth, there is no particular limitation as long as the above storage environment can be maintained, and for example, indoor storage in a storage room, storage in a package (bundled body) wrapped (bundled) with a wrapping material (bundling material), and a combination thereof can be given. In the present disclosure, the terms "package" and "bundling" can be used interchangeably as terms indicating a wrapped object. The wrapping material can include a box and a film, and the like. In each case, it is preferable to control the average dew point and the temperature of the atmosphere in direct contact with the glass cloth, the pressure optionally controlled, in the storage environment, to be within the above range. In addition, from the viewpoint of avoiding wrinkles and the like of the glass cloth and / or the miniaturization of the storage space, the glass cloth is preferably stored in a rolled state. If it is in a rolled state, it is easy to minimize the area of the storage environment in contact with the external environment, and to reduce the volume of the gas inside when wrapped, and it is possible to more effectively suppress the temporal increase in the dielectric loss tangent.

[0206] For the storage room and the wrapping material for storing the glass cloth, it is preferable that the sealing property be high from the viewpoint of easily maintaining the average dew point and the temperature. It is preferable that the storage room and the wrapping material be configured to dehumidify in such a manner that the average dew point of the inside (storage environment) is maintained at 18°C dp or lower, on the basis of the high sealing property, or as an alternative thereto. That is, it is preferable that the storage room and the wrapping body themselves have a dew point control unit as described above. The average dew point of the inside (storage environment) is preferably -50°C dp or higher and 18°C dp or lower. The lower limit value of the average dew point of the inside (storage environment) can be more preferably -40°C dp or higher, -32°C dp or higher, -30°C dp or higher, -20°C dp or higher, -10°C dp or higher, 0°C dp or higher, 10°C dp or higher, or 13°C dp or higher. The upper limit value of the average dew point of the inside (storage environment) that can be arbitrarily combined with the above lower limit value is more preferably 15°C dp or lower, 10°C dp or lower, 5°C dp or lower, 0°C dp or lower, -5°C dp or lower, -10°C dp or lower, -15°C dp or lower, -20°C dp or lower, or -21°C dp or lower.

[0207] <Wrapping material>

[0208] From the viewpoint of easily maintaining the dew point of the storage environment, the water vapor permeability of the wrapping material (box, film, and the like) at a measurement temperature of 40°C and a measurement humidity of 90% Rh is preferably 8 g / (m 2 × 24 hr) or lower, more preferably 4 g / (m 2 × 24 hr) or lower, further preferably 2 g / (m 2 × 24 hr) or lower, still further preferably 1 g / (m 2 × 24 hr) or lower, particularly preferably 0.3 g / (m 2 × 24 hr) or lower, and particularly preferably 0.1 g / (m 2below. By making the water vapor permeability of the packaging material 8 g / (m 2 below, the amount of permeated moisture decreases, and the dew point is easily controlled. The lower limit value of the water vapor permeability is 0 g / (m 2 above, for example, more than 0 g / (m 2 above, for example, more than 0 g / (m

[0209] In the case where the glass cloth in a roll state is stored as a package in which the glass cloth is wrapped with a box and / or a film-shaped packaging material, it is preferable that a moisture absorbent is enclosed in the package. It is more preferable that the moisture absorbent is enclosed between the roll and the packaging material. Thereby, the moisture inside the package can be absorbed, and in addition, the moisture that has permeated the box and / or the film-shaped packaging material to flow into the storage environment during storage can also be absorbed.

[0210] From the viewpoint of easily maintaining the dew point and the temperature, it is preferable that the glass cloth is wrapped with a box and / or a film-shaped packaging material, and the opening portion thereof is sealed. The sealing can be performed, for example, by heat caulking the opening portion or the like. Note that the sealing refers to a state in which the opening portion is firmly closed without a gap, and the temperature, the dew point, and the air pressure in the storage environment of the glass cloth can be controlled to be below a certain reference. In addition, the sealed state is preferably encapsulated in a manner that prevents the intrusion of solids and liquids and gases. By suppressing the intrusion of solids, liquids, and gases, the effect of suppressing the increase in the dielectric loss tangent of the glass cloth is easily obtained.

[0211] In the case where a box is used as the packaging material, as the box, there is no limitation as long as the water vapor permeability satisfies the above range, and the box is a size in which the opening portion can be sealed, and for example, a box made of metal, plastic, wood, corrugated paper, or a box made by combining these or the like can be cited. From the viewpoint that the water vapor permeability easily satisfies the above range and the viewpoint that it is easily recycled, the material is preferably metallic or plastic, and more preferably metal. Note that here, the box refers to a movable container having sealing properties for isolating the glass cloth from the outside air. One or more glass cloths can also be stored in the box.

[0212] When using film as packaging material, there are no limitations on the type of film as long as the water vapor transmission rate meets the above-mentioned range. Examples include ceramic vapor-deposited film, aluminum vapor-deposited film, aluminum foil, and aluminum laminated film. From the viewpoint that the water vapor transmission rate can easily meet the above-mentioned range, aluminum foil and aluminum laminated film are preferred. In addition, 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, further preferably 80 μm or more, and particularly preferably 90 μm or more. By making the thickness 50 μm or more, the water vapor transmission rate is easily reduced, and pinholes caused by wrinkles, scratches, etc., are less likely 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.

[0213] Fiberglass cloth is preferably stored in a package made of film, which is a roll of glass cloth wrapped around a hollow cylindrical core tube having a central columnar cavity (hollow portion). During handling, the glass cloth roll is usually lifted by inserting a support rod into the hollow portion of the core tube. From the viewpoint of maintaining the above-mentioned storage environment, it is preferable to package the glass cloth roll with packaging material having a minimum surface area. However, in this method, the hollow portion of the core tube cannot be utilized when handling the glass cloth roll, making the handling process complicated. Therefore, from the viewpoint of ease of handling the glass cloth roll, the glass cloth roll is preferably configured such that the film-like packaging material has a recess extending into the hollow portion from one or both ends of the core tube, or the film-like packaging material is annular (ring-shaped) penetrating the hollow portion of the core tube, thereby enabling the insertion of a support rod into the hollow portion of the core tube. Alternatively, from the viewpoint of ease of handling of the glass cloth roll, it is preferable that the glass cloth is sealed with a thin film-like packaging material and a core tube to isolate it from the external environment.

[0214] Figure 1 This is a schematic diagram illustrating the axial cross-section of the core tube of the glass cloth packaging body of this disclosure. For example, as shown... Figure 1 As schematically shown in (1a), the glass cloth package 10 may have a hollow cylindrical core tube 11, glass cloth 12 wound around the core tube 11, and a film 13 surrounding the core tube 11 and the glass cloth 12 as a whole. The film 13 has a recess 14 from one end of the core tube 11 toward the inside of the hollow portion, thereby configuring a support rod to be inserted into the interior of the hollow portion. In addition, as Figure 1As schematically shown in (1b), the glass cloth packaging 10 may also 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. The outer film 13a and the inner film 14b are joined at the joint 15 by heat pressing or the like. Thus, the films 13a and 13b, as a whole, have an annular shape that surrounds the core tube 11 and the glass cloth 12. If the packaging material is annular, it becomes a shape in which the external environment penetrates the hollow portion of the core tube, so the support rod can penetrate the hollow portion from both sides of the packaging body, further improving the processability. The joining of the films is not particularly limited as long as it can seal the opening and eliminate gaps; for example, methods such as heat pressing, tape, or adhesive can be used. Or, as Figure 1 As schematically shown in (1c), the film 13 covering the outside of the glass cloth 12 and the core tube 11 can also be joined at the joint 15 located on the exposed outer surface of the core tube 11. Thus, the glass cloth 12 is sealed by the film 13 and the core tube 11, isolating it from the external environment. In this manner, since the external environment penetrates the hollow portion of the core tube, the support rod can penetrate the hollow portion from both sides of the packaging body. Furthermore, since there is no film inside the core tube, pinholes are less likely to occur when inserting or removing the support rod or when lifting the roll for handling, further improving processability. The joining of the film-like packaging material to the core tube is not particularly limited as long as the opening is sealed tightly to eliminate gaps; for example, methods such as using tape or adhesive to stick the opening can be employed.

[0215] From the viewpoint of easy insertion of the support rod, the proportion of the volume of the hollow portion of the core tube that becomes the internal space of the film-like packaging is preferably 70% or less, more preferably 50% or less, even more preferably 30% or less, and particularly preferably 10% or less. The lower limit of the internal volume of the packaging relative to the volume of the hollow portion can be 0% or more. For example, in Figure 1 In the manner schematically shown in (1c), the volume of the interior of the package is 0% relative to the volume of the hollow portion.

[0216] <Core Tube>

[0217] The core tube around which the glass cloth in a roll is wound has a cylindrical hollow (hollow portion) at the center from the viewpoint of handling and post-processing. The material of the core tube can be paper, resin, fiber-reinforced plastic (hereinafter referred to as "FRP"), metal, or the like, and is preferably paper, resin, or FRP from the viewpoint of preventing the mixing of metal foreign matter into the glass cloth. Generally, the core tube has a certain degree of thickness from the viewpoint of the balance between weight and strength. In particular, in a glass cloth roll, the weight of the glass cloth itself is large, and the glass cloth is strongly bent in a core tube having a small diameter, and thus the core tube is thickened and lightened. 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 in the past. However, as a result of research, it has been found that water vapor can permeate even the core tube made of paper, resin, or FRP due to the thin thickness of the entire core tube in order to reduce the weight of the core tube, the combination of materials having a thin thickness, and the presence of a joint or the like in the combined materials. Therefore, it is preferable to use a core tube having a low water vapor permeation rate.

[0218] From the viewpoint of easily controlling the amount of moisture inside the packaging material, the water vapor permeation rate of the core tube measured under conditions of 40°C and 90% Rh is preferably 8 g / (m 2 × 24 hr) or less, more preferably 4 g / (m 2 × 24 hr) or less, further preferably 2 g / (m 2 × 24 hr) or less, more further preferably 1 g / (m 2 × 24 hr) or less, particularly preferably 0.3 g / (m 2 × 24 hr) or less, and particularly preferably 0.1 g / (m 2 × 24 hr) or less. By making the water vapor permeation rate of the core tube 8 g / (m 2 × 24 hr) or less, the amount of permeated moisture is reduced, and the dew point is easily controlled. The lower limit of the water vapor permeation rate is 0 g / (m 2 × 24 hr) or more, and for example, exceeds 0 g / (m 2 As a method of controlling the water vapor permeation rate of the core tube within the above range, there are a method of applying a moisture-proof paint to the core tube, a method of performing sputtering plating, a method of increasing the thickness of the core tube, a method of using a material having a low water vapor permeation rate in the core tube, and a method of winding a film having a low water vapor permeation rate around the core tube.

[0219] <Package surface area>

[0220] The smaller the surface area of the glass cloth package packaged by the packaging material, the easier it is to maintain the storage environment. The package surface area is not limited as long as the dew point of the storage environment thereof satisfies the range of the present disclosure, and is preferably 10 m 2 More preferably, it is 7 m2 Further preferably, the lower limit value of the surface area of the package is 5 m2. 2 Still more preferably, the lower limit value of the surface area of the package is 4 m2. 2 The lower limit value of the surface area of the package is not limited as long as the glass cloth is sealed from the outside environment. In the present disclosure, for example, in the case where the glass cloth is sealed from the outside environment by a film, the "surface area of the package" refers to the area of the film; in the case where the glass cloth is sealed from the outside environment by a box, the "surface area of the package" refers to the area of the outer surface of the box; and in the case where the glass cloth is sealed from the outside environment by a film and a core pipe, the "surface area of the package" refers to the sum of the area of the film and the area of the outer diameter side surface of the core pipe that separates the outside environment and the storage environment.

[0221] <Storage room>

[0222] The storage room for storing the glass cloth refers to a room in which the dew point and the temperature are controlled. From the viewpoint of space saving, it is preferable that the glass cloth be stored in a state where a plurality of rolls are concentrated in the room. The glass cloth in the state of a roll can also be stored in the storage room in the form of a package in which the glass cloth is wrapped with a packaging material in the form of a box and / or a film.

[0223] <Method for manufacturing glass cloth>

[0224] The method for manufacturing the glass cloth used in the method for storing the glass cloth according to the present disclosure includes a step of weaving a glass cloth by weaving glass filaments each including a plurality of glass filaments as warp and weft. The method for manufacturing the glass cloth can further include a step of performing a heat deoiling treatment (heat cleaning) on the glass filaments or the glass cloth, and a step of treating the glass filaments or the glass cloth with a surface treatment agent. The method for manufacturing the glass cloth can optionally further include at least one of a step of opening the glass cloth, and a step of wrapping the glass cloth with a packaging material (a box, a film, and the like).

[0225] <Weaving step>

[0226] The weaving method is not particularly limited as long as the weft and the warp are woven in such a manner that a predetermined woven structure is obtained. The preferable constitution and composition of the glass filaments used, and the woven structure are as described above.

[0227] <Heat deoiling step>

[0228] The heating and deoiling process can be performed on glass filaments, or alternatively, on woven glass cloth. In other words, the process of weaving glass filaments to obtain glass cloth can be performed before the heating and deoiling process, or can be performed midway, or can be performed thereafter. The heating and deoiling process can use any of the following methods: (1) a method of heating and deoiling glass filaments or glass cloth (hereinafter, also simply referred to as "glass" in this process) at a relatively low temperature (e.g., less than 600°C) for a long period of time (e.g., more than 24 hours), and (2) a method of heating and deoiling glass at a relatively high temperature (e.g., 600°C to 1600°C) for a long period of time or for a short period of time (e.g., less than 24 hours). From the viewpoint of obtaining glass cloth having excellent dielectric loss tangent, the method of (2) is preferably used. In particular, glass cloth composed of glass filaments having a Si content of 95.0 mass% or more and 100 mass% or less, calculated as SiO2, can be heated and deoiled at a temperature of 600°C or higher. Thereby, the dielectric loss tangent of the glass cloth can be easily reduced.

[0229] (1) In the case of heating at a relatively low temperature, the temperature for heating and deoiling is preferably 100°C or higher and 500°C or lower, more preferably 250°C or higher and 450°C or lower, and further preferably 350°C or higher and 450°C or lower. In addition, the heating time for heating and deoiling in the case of (1) can be appropriately selected, and for example, is preferably 24 hours or more and 300 hours or less, more preferably 48 hours or more and 200 hours or less, and further preferably 72 hours or more and 150 hours or less. If the heating and deoiling temperature and time are in the above-described ranges in combination, the sizing agent adhering to the glass can be easily removed sufficiently.

[0230] On the other hand, (2) in the case of heating at a relatively high temperature, the temperature for heating and deoiling is preferably 600°C or higher and 1500°C or lower, more preferably 800°C or higher and 1300°C or lower, and further preferably 900°C or higher and 1100°C or lower. When the heating and deoiling temperature is 600°C or higher, organic matter such as a residue of the sizing agent adhering to the glass can be easily removed sufficiently, and thus the dielectric loss tangent of the glass cloth can be easily reduced, and in addition, the removal time can be shortened. When the heating and deoiling temperature is 1500°C or lower, the devitrification of the glass can be easily suppressed, and thus the strength of the glass cloth can be easily prevented from being reduced. In addition, the heating time for heating and deoiling in the case of (2) can be appropriately selected, and for example, is preferably 3 seconds or more and 72 hours or less, more preferably 3 seconds or more and 12 hours or less, further 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.

[0231] The heating unit in the heating and deoiling can use known heating methods, heating media, heating mechanisms, heating devices, and heating components, etc. as long as the heating and deoiling temperature can be properly controlled. For example, it can be (1) a method of heating the glass in a heating furnace, (2) a method of contacting the glass with a heating element, (3) a method of contacting the glass with high-temperature steam, etc. The heating can be performed in a closed system or an open system, sequentially or continuously, or a combination of the closed system and the open system.

[0232] In the case of the closed system, from the viewpoint of properly heating by the heating unit, it is preferable to arrange the glass in the heating furnace. At this time, from the viewpoints of the storage space and the heating range, it is preferable to heat while storing the glass cloth in a roll state. In addition, from the viewpoints of improving the removal efficiency of the organic matter and shortening the removal time of the organic matter, etc., it is also preferable to heat while transporting the glass in the heating furnace.

[0233] In the case of the open system, from the viewpoint of the heated area, it is preferable to heat while transporting the glass in a roll-to-roll manner. The heating temperature is preferably 600°C or higher and 1500°C or lower, more preferably 800°C or higher and 1300°C or lower, and further preferably 900°C or higher and 1100°C or lower, as described above. The transportation of the glass can be performed by a roll-off mechanism and a winding mechanism, for example.

[0234] As the heating unit of the heating furnace, various heating units such as an electric heater, a burner, etc. can be given, and a gas type single radiant tube burner or an electric heater is preferable. A plurality of units can be combined to perform heating.

[0235] From the viewpoint of the heating efficiency, the heating furnace preferably has a unit for discharging gas generated in the heating furnace and / or an air circulation unit. The gas discharge unit can be a nozzle, a gas pipe, a small hole, an exhaust valve, etc. The air circulation unit can be a fan, an air conditioning device, etc.

[0236] The heating furnace can be any of the following: an intermittent type that houses the glass (for example, a roll of glass cloth) and can perform heating at a prescribed atmosphere temperature, and a continuous type that can perform heating while continuously passing the glass through the heating furnace (for example, heating while transporting by roll-to-roll). In order to efficiently remove the organic matter attached to the surface of the glass, the heating furnace is preferably the continuous type.

[0237] As the method of heating the glass, the above-described heating furnace can be used, but from the viewpoint of low operating cost, the heating can also be performed by contacting a member heated to a prescribed temperature with the glass.

[0238] The shape of the contact member is not particularly limited as long as heating can be performed while appropriately controlling the heating and deoiling temperature, and a roll shape (heating roll method) is preferable from the viewpoint of easiness of glass conveyance. As a member that can heat glass in a roll shape, a roll that can be used in a high temperature region and has less temperature deviation in the width direction and that heats in an induction heating method is preferable. When heating glass using a contact member, the temperature of the contact member is considered to be approximately equal to the surface temperature of the glass.

[0239] As the glass is continuously heated, carbide sometimes adheres to the heating roll. In order to remove the carbide adhering to the heating roll, the above heating roll method preferably has a mechanism for removing adhering foreign matter, such as a doctor blade or the like.

[0240] <Surface treatment step>

[0241] The surface treatment step can be performed on glass filaments, and alternatively, on woven glass cloth. In other words, the step of weaving glass filaments to obtain glass cloth can be performed before the surface treatment step, can be performed midway, or can be performed thereafter. The surface treatment step can have, for example, a coating step of adhering a silane coupling agent to the surface of glass filaments or glass cloth (hereinafter, also simply referred to as "glass" in this step) using a treatment liquid having a concentration of 0.1 to 0.5 mass%. The surface treatment step can further have a fixing step of fixing the silane coupling agent to the surface of the glass by heat drying. Thereby, it becomes easier to appropriately surface-treat the glass.

[0242] As a method of applying a treatment liquid to glass in the coating step, there can be mentioned: (a) a method of immersing or passing glass in a treatment liquid accumulated in a tank (hereinafter, referred to as "immersion method"), (b) a method of applying a treatment liquid to glass using a roll coater, die coater, gravure coater, or the like. In the case of using the immersion method, the immersion time of the glass cloth in the treatment liquid is preferably set to 0.5 seconds or more and 1 minute or less. Alternatively, in the case of using the immersion method, the glass can be passed through the treatment liquid at a conveyance speed of 10 to 50 m / min while imparting a predetermined tension (for example, 100 to 250 N) to the glass. Alternatively, after applying a treatment liquid to glass, the solvent contained in the treatment liquid can be heat-dried by a method of hot air, electromagnetic wave, or the like. In order to easily apply a surface treatment agent uniformly to the surface of glass, it is preferable to extrude the glass cloth using a rubber-made roll at a certain pressure after immersing the glass cloth in a surface treatment liquid.

[0243] The concentration of the surface treatment agent in the treatment liquid is preferably 0.1 to 0.5 mass%, more preferably 0.1 to 0.45 mass%, and further preferably 0.1 to 0.4 mass%, based on the total mass of the treatment liquid. Thereby, it becomes easier to appropriately surface-treat the glass.

[0244] In the fixing step, in order to sufficiently perform the reaction of the silane coupling agent with the glass, the heat-drying temperature is preferably 80°C or higher, more preferably 90°C or higher. From the viewpoint of preventing deterioration of the organic functional group possessed by the silane coupling agent, the heat-drying temperature is preferably 300°C or lower, more preferably 180°C or lower.

[0245] <Opening step>

[0246] The method for manufacturing the glass cloth can further include a step of opening the glass cloth. As the opening method in the opening step of the glass cloth, for example, a method of opening the glass cloth by spraying water (high-pressure water opening), an oscillating washing machine, ultrasonic water, or a calender machine, etc. can be used. The composition of the glass cloth before and after opening is generally not changed.

[0247] <Packaging step>

[0248] The method for manufacturing the glass cloth can further include a step of packaging the glass cloth with a packaging material, such as a film or a box. Thereby, it is easy to maintain the storage environment of the glass cloth. The details of the packaging material are as described above, and thus are omitted here. In the packaging step, the dew point and the temperature of the environment in which the glass cloth is directly contacted, and any pressure, etc. are preferably controlled in advance to the storage environment of the present disclosure, and then the glass cloth is packaged. The storage environment is as described above, and thus is omitted here. In addition, as the sealing method, for example, a method of wrapping the glass cloth with a film and heat-sealing the opening portion, a method of putting the glass cloth in a box and making the opening portion tight to eliminate the gap, a method of sticking the opening portion with a tape or the like, etc. can be used.

[0249] In the case where the glass cloth in the state of being wound in a roll around a core pipe of a hollow column shape is packaged with a film, for example, the glass cloth roll is covered with a film and the opening portion is heat-sealed, the remaining film is pressed into the hollow portion from one end or both ends of the core pipe, etc., whereby a recess extending into the hollow portion from one end or both ends of the core pipe can be formed. As a method of packaging in a circular ring shape through the hollow portion of the core pipe, for example, a method of inserting a tubular film into the hollow portion of the core pipe of the glass cloth roll, covering the glass cloth roll with another film, and heat-sealing the opening portion of the tubular film with the tubular film passing through the hollow portion, etc. can be used. As a method of packaging by joining the film to the core pipe, for example, a method of sticking the film to the surface of the core pipe without a gap by using a tape, etc. can be used.

[0250] The above-described steps do not necessarily need to be performed in a manner that can be distinguished as different steps, and a plurality of steps can be performed together (at the same time). In addition, the method for manufacturing the glass cloth can have any step in addition to the above-described steps. For example, a longitudinal cutting step can be provided after the opening step. In addition, if possible, the order of the above-described steps can be changed.

[0251] Glass cloth package

[0252] The glass cloth package of the present disclosure contains a packaging material and a glass cloth housed in the interior of the packaging material. The glass cloth is composed of glass filaments containing a plurality of filaments as warp and weft, and the tangent of the dielectric loss angle at 10 GHz is 0.00200 or less. Also, the packaging material housing the above glass cloth is sealed, and the water vapor permeability of the packaging material at a measurement temperature of 40°C and a measurement humidity of 90% Rh is 8 g / (m 2 ×24 hr) or less. Conventionally, it was thought that in the temperature region below 100°C, the reaction in which moisture causes the Si-O-Si bond to break and generate Si-OH groups is not activated, and therefore in the temperature region below 100°C, even if a glass cloth having a tangent of the dielectric loss angle at 10 GHz of 0.00200 or less is stored for a long period of time, the tangent of the dielectric loss angle of the glass cloth does not change over time. Therefore, the storage method of the glass cloth is not particularly considered, and even if a glass cloth having a low tangent of the dielectric loss angle at the time of manufacture, the tangent of the dielectric loss angle sometimes increases over time. In this regard, the glass cloth package of the present disclosure can suppress the generation of Si-OH groups due to the moisture invading the storage environment from the outside environment, and therefore can suppress the increase in the tangent of the dielectric loss angle of the glass cloth over time. Note that in the present disclosure, "suppress" does not mean that the tangent of the dielectric loss angle does not increase at all, but only that the increase in the tangent of the dielectric loss angle is suppressed to some extent.

[0253] <Glass cloth>

[0254] The glass cloth in the glass cloth package, the tangent of the dielectric loss angle of the glass cloth, the glass filaments, the silane coupling agent, and the loss on ignition value are as described in the <Glass cloth> to the <Loss on ignition value> of the above-described <Method for storing glass cloth>, and therefore these descriptions are incorporated by reference for the glass cloth package.

[0255] <Packaging material>

[0256] The packaging material can house and seal the glass cloth. The water vapor permeability of the packaging material (box and film, etc.) measured under conditions of 40°C and 90% Rh is 8 g / (m 2 ×24 hr) or less. Sealing means that the opening portion is firmly closed in a manner without gaps, and the temperature, dew point, and air pressure in the glass cloth package can be controlled to a state below a certain reference. Also, the sealed state is preferably packed in a manner to prevent the invasion of solids and liquids and gases. By suppressing the invasion of solids, liquids, and gases, the effect of suppressing the increase in the tangent of the dielectric loss angle of the glass cloth described in the present disclosure is easily obtained. As the packaging material, there is no limitation as long as the above-described constitution is satisfied, and for example, a film and / or a box-shaped packaging material can be mentioned.

[0257] <Water vapor permeability>

[0258] The water vapor permeability of the packaging material is 8 g / (m 2 × 24 hr) or less at a measurement temperature of 40°C and a measurement humidity of 90% Rh. If the packaging material is such, the amount of moisture inside the packaging material can be controlled, and the increase in the dielectric loss tangent of the glass cloth over time due to the moisture 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 permeability of the packaging material is preferably 8 g / (m 2 × 24 hr) or less, more preferably 4 g / (m 2 × 24 hr) or less, further preferably 2 g / (m 2 × 24 hr) or less, more further preferably 1 g / (m 2 × 24 hr) or less, particularly preferably 0.3 g / (m 2 × 24 hr) or less, and most preferably 0.1 g / (m 2 × 24 hr) or less at a measurement temperature of 40°C and a measurement humidity of 90% Rh. By making the water vapor permeability of the packaging material 8 g / (m 2 × 24 hr) or less, the amount of permeated moisture is small, and the amount of moisture inside the packaging material can be easily controlled. The lower limit of the water vapor permeability is 0 g / (m 2 × 24 hr) or more, for example, more than 0 g / (m 2 × 24 hr).

[0259] <Thin Film>

[0260] As the packaging material, a thin film can also be used. The water vapor permeability is not limited as long as it satisfies the above range, and for example, ceramic vapor deposition films, aluminum vapor deposition films, aluminum foils, aluminum laminated films, and the like can be given. From the viewpoint that the water vapor permeability easily satisfies the above range, an aluminum foil or an aluminum laminated film is preferred. In addition, the thickness of the thin film is preferably 30 μm or more and 500 μm or less. The lower limit of the thickness of the thin film is preferably 50 μm or more, more preferably 70 μm or more, further preferably 80 μm or more, and particularly preferably 90 μm or more. By making the thickness 50 μm or more, the water vapor permeability easily becomes small, and in addition, pinholes due to wrinkles, scratches, and the like are less likely to occur. The upper limit of the thickness of the thin film is preferably 400 μm or less, 300 μm or less, 200 μm or less, or 170 μm or less.

[0261] The glass cloth is preferably a package in which the glass cloth is wrapped with a film in a state in which the glass cloth is wound around a hollow cylindrical core pipe having a cylindrical hollow (hollow portion) in the center (also referred to simply as a "glass cloth package"). For the same reasons as described in the above-mentioned <Packaging material> of the "Storage method of glass cloth", the film is preferably configured so that a support rod can be inserted into the hollow portion of the core pipe by having a recess extending into the hollow portion from one end or both ends of the core pipe, or by the film-like packaging material being a circular ring (ring shape) that penetrates the hollow portion of the core pipe. Alternatively, the glass cloth is preferably sealed from the outside environment by the film-like packaging material and the core pipe. As specific examples thereof, as described above, for example, the configuration shown schematically in (1a) to (1c) of FIG. 10 is preferable. Figure 1

[0262] From the viewpoint of easy insertion of the support rod, the proportion of the volume of the space inside the package to the volume of the hollow portion of the core pipe is preferably 70% or less, more preferably 50% or less, still more preferably 30% or less, and particularly preferably 10% or less. The lower limit of the volume of the inside of the package with respect to the volume of the hollow portion can be 0% or more. For example, in the configuration shown schematically in (1c) of FIG. 10, the volume of the inside of the package with respect to the volume of the hollow portion is 0%. Figure 1

[0263] <Core pipe>

[0264] For the same reasons as described in the above-mentioned <Core pipe> of the "Storage method of glass cloth", the material of the core pipe is preferably paper, resin, or FRP. In addition, the water vapor permeability of the core pipe, measured under conditions of 40°C and 90% Rh, is preferably 8 g / (m 2 × 24 hr) or less, more preferably 4 g / (m 2 × 24 hr) or less, still more preferably 2 g / (m 2 × 24 hr) or less, yet more preferably 1 g / (m 2 × 24 hr) or less, particularly preferably 0.3 g / (m 2 × 24 hr) or less, and particularly preferably 0.1 g / (m 2 × 24 hr) or less. The lower limit of the water vapor permeability is 0 g / (m 2 × 24 hr) or more, for example, more than 0 g / (m 2 × 24 hr).

[0265] <Box-shaped packaging material>

[0266] ​​As the packaging material, a box-shaped packaging material can also be used. The water vapor permeability is not limited as long as it satisfies the above range, and the size that enables sealing of the opening portion, such as a metal, plastic, wood, corrugated cardboard box, or a box made by combining them, can be cited. From the viewpoint that the water vapor permeability easily satisfies the above range and the viewpoint that it is easy to recycle, the material is preferably metallic or plastic, and more preferably metal. Note that, here, the box refers to a movable, sealed container that insulates the glass cloth from the outside air. One or more glass cloths can also be stored in the box.

[0267] <Package surface area>

[0268] For the same reasons as described in the above "Glass cloth storage method" <Core tube>, the package surface area is not limited as long as the dew point of its storage environment satisfies the range of the present disclosure, and is preferably 10 m 2 More preferably, 7 m 2 Further preferably, 5 m 2 Still more preferably, 4 m 2 The lower limit value of the package surface area is not limited as long as it enables sealing of the glass cloth from the outside environment.

[0269] <Dew point inside the glass cloth package>

[0270] The dew point at the air pressure inside the glass cloth package is preferably 18°C dp or less. In the present disclosure, the dew point refers to the dew point at the air pressure of the storage environment unless otherwise specified. If the dew point at the air pressure inside the packaging material is 18°C dp or less, the dielectric loss 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 value of the dew point can be more preferably -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 value of the dew point, which can be arbitrarily combined with the above lower limit values, is more preferably 15°C dp or less, 10°C dp or less, 5°C dp or less, 0°C dp or less, -5°C dp or less, -10°C dp or less, -15°C dp or less, -20°C dp or less, or -21°C dp or less.

[0271] Methods for controlling the dew point within the aforementioned range can utilize known humidity control methods, humidity control media, humidity control mechanisms, and humidity control devices. Examples include: (1) using a desiccant; (2) replacing the atmosphere inside the packaging material with a gas of a specified moisture content (e.g., a dry gas); (3) dehumidifying the atmosphere inside the packaging material by utilizing condensation at low temperatures; (4) reducing pressure to achieve a specified moisture content in the atmosphere inside the packaging material; and (5) combinations thereof. For example, by performing the above-mentioned controls (1) to (5) and sealing the packaging material, it is easy to obtain the effect of suppressing the rise of the dielectric loss tangent.

[0272] When using a dehumidifier to control the dew point, there are no limitations on the type of dehumidifier as long as it can control the dew point within the aforementioned range. Examples include compressor-type dehumidifiers that utilize condensation at low temperatures and desiccant-type dehumidifiers (zeolite type) that regenerate the desiccant multiple times through heat.

[0273] <Desiccant>

[0274] In glass cloth packaging, it is preferable to seal a desiccant inside the packaging material. This allows the desiccant to absorb moisture from inside the packaging material, as well as moisture that seeps into the packaging material during storage.

[0275] From the viewpoint of hygroscopicity, the desiccant is preferably at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, calcined diatomaceous earth, synthetic zeolite, clay-based desiccants, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate. Preferably, at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, and calcined diatomaceous earth is preferred. Furthermore, from the viewpoint of space occupation and packaging (bundling) form, sheet-shaped desiccant is preferred.

[0276] There is no limitation on the amount of desiccant used, but it is preferable to use an appropriate amount based on the desiccant's hygroscopic capacity (absorption capacity and absorption time) and storage period. Regarding the absorption capacity, it is preferable to use a sufficient amount. That is, it is preferable that the maximum absorption capacity of the desiccant is greater than the moisture content in the atmosphere.

[0277] As described in the section on "Desiccant" of the aforementioned "Methods for Storage of Glass Cloth", the amount of desiccant to be added is preferably 0.0030 or less, more preferably 0.0023 or less, even more preferably 0.0012 or less, and particularly preferably 0.0005 or less, as determined by the following formula (2). The value determined by the following formula (2) may also be 0.

[0278] WVTR[g / (m 2 ×24hr)] × Packaging surface area [m 2 ] / Amount of desiccant sealed in [g]…(2)

[0279] {In formula (2), WVTR is the water vapor transmission rate at a measurement temperature of 40°C and a measurement humidity of 90% Rh.}

[0280] The dew point change ratio in the package having the moisture absorbent inside is preferably 3.0 or less, more preferably 1.0 or less, further preferably 0.50 or less, more further preferably 0.30 or less, particularly preferably 0.10 or less, or 0.02 or less, as described in the above-mentioned "Storage method of glass cloth" under the heading of "Moisture absorbent". The dew point change ratio can also be a negative value.

[0281] <Dry gas>

[0282] In the case where a dry gas is used in the control of the dew point inside the packaging material, a gas having a dew point temperature of 18°C dp or less (dry gas) is preferably used. If such a dry gas is used, it is easy to control the atmosphere so that the dew point inside the packaging material is 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 is more preferably -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 is more preferably 15°C dp or less, 10°C dp or less, 5°C dp or less, 0°C dp or less, -5°C dp or less, -10°C dp or less, -15°C dp or less, -20°C dp or less, or -21°C dp or less.

[0283] As the dry gas, for example, dry air having the above-mentioned dew point temperature range, or a gas having the above-mentioned dew point temperature range and containing at least one selected from the group consisting of nitrogen, argon, and oxygen can be used. From the viewpoint of ease of handling, dry air is preferably used.

[0284] <Temperature inside the glass cloth package>

[0285] The temperature in the glass cloth package, preferably the packaging material, is preferably 100°C or less. When the temperature is 100°C or less, the temporal increase in the dielectric loss tangent of the glass cloth during storage for a long period of time (for example, 30 days or more) can be effectively suppressed. The temperature of the glass cloth storage environment (the inside of the packaging material) during storage of 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, further preferably 35°C or less, more further preferably 30°C or less, and particularly preferably 25°C or less. The lower limit of the average temperature can be preferably 10°C or more or 20°C or more.

[0286] <Pressure inside the glass cloth package>

[0287] In the case of performing the reduced pressure in the control of the dew point inside the packaging material, it is preferable to perform the control in a manner that the reduced pressure becomes less than the atmospheric pressure (10 5 Pa). The method of controlling the air pressure inside the packaging material to the reduced pressure less than the atmospheric pressure is not limited as long as it can control the dew point to the above range, and known reduced pressure control methods, reduced pressure control media, reduced pressure control mechanisms, reduced pressure control devices, and the like can be used, and for example, a vacuum pump can be cited.

[0288] For example, by performing the control in a manner that the air pressure inside the packaging material becomes the reduced pressure less than the atmospheric pressure, and sealing the packaging material, the effect of suppressing the rise in the dielectric loss tangent is easily obtained. The air pressure around the glass cloth at the time of storing or bundling the glass cloth is preferably 10 4 Pa or less, and more preferably 10 3 Pa or less. The lower limit value of the air pressure is not particularly limited, and it is preferable to be more than 0 Pa or 10 Pa or more.

[0289] <Storage Period>

[0290] The storage period of the glass cloth, that is, the period of maintaining the sealing of the packaging material in the glass cloth packaging body in the present disclosure is not particularly limited, and it is preferable to be 30 days or more and 5 years or less from the viewpoint of the time required for transporting the glass cloth, and the improvement of the supply stability, and the like. The lower limit value of the storage period is preferably 30 days or more, more preferably 90 days or more, further preferably 180 days or more, still further preferably 365 days or more, and particularly preferably 730 days or more. In addition, the upper limit value of the storage period of the glass cloth is preferably 5 years or less, and more preferably 3 years or less from the viewpoint of the reduction of the storage cost, and the like. If the storage period is within the above range, the effect of manufacturing the glass cloth packaging body of the present disclosure can be sufficiently obtained. The longer the storage period, the more significantly the effect of suppressing the rise in the dielectric loss tangent can be obtained.

[0291] <Method for Manufacturing Glass Cloth Packaging Body>

[0292] The glass cloth packaging body of the present disclosure can be manufactured by packaging the glass cloth manufactured by the method described in the item of the above-described <Method for Manufacturing Glass Cloth> using the method described in the above-described <Packaging Step> by incorporating these descriptions into the method for manufacturing the glass cloth packaging body.

[0293] Example 1

[0294] <Method for Measurement and Evaluation>

[0295] <Method for Measuring the Weight per Unit Area (Cloth Weight)>

[0296] The unit area weight of the glass cloth was calculated by cutting the glass cloth to a prescribed size, dividing the weight of the glass cloth by the area of the sample. In this example or comparative example, the glass cloth was cut to a size of 10 cm x 10 cm, and the weight of the glass cloth was measured 10 times, and the average value was used as the unit area weight of the glass cloth. 2

[0297] <Method for measuring the conversion thickness>

[0298] The glass cloth is a discontinuous planar body in which air is present between the glass fibers. Therefore, the conversion thickness was calculated by dividing the unit area weight of the glass cloth (mass of the cloth) by the density of the glass.

[0299] Specifically, the following equation was used: Conversion thickness (pm) = Unit area weight (g / m 2 ) ÷ Density (g / cm 3 )

[0300] The conversion thickness was thus calculated. The value of the conversion thickness was used for the measurement using the resonance method.

[0301] <Method for measuring the dielectric loss tangent>

[0302] The dielectric loss tangent of each glass cloth was measured in accordance with IEC 62562. Specifically, a glass cloth sample that was cut to a size required for the measurement using a split post resonator was stored in a constant temperature and humidity oven at 23°C, 50% RH for 8 hours or more. Then, for the sample after storage, a split post resonator (manufactured by EM Labo) and an impedance analyzer (manufactured by Agilent Technologies) were used to measure the dielectric properties at 10 GHz. The measurement was performed 5 times for each sample, and the average value was calculated. The conversion thickness described above was used as the thickness of each sample. Note that in IEC 62562, a method for measuring the dielectric properties of fine ceramics used in microwave circuits in the microwave band is mainly described.

[0303] <Method for measuring the loss on ignition of the glass cloth>

[0304] The loss on ignition of the glass cloth was measured in accordance with JIS R3420.

[0305] <Method for measuring the temperature and dew point>

[0306] ​The temperature and dew point were measured using a handheld dew point meter DM70 manufactured by Vaisala Corporation. Based on the measured dew point, the dew point under the air pressure of the storage environment was measured using a DMP74A probe or a DMP74B probe, and a MI70 indicator. Specifically, the DMP74A probe was used in the case where the dew point was more than -30°C dp, and the DMP74B probe was used in the case where the dew point was -30°C dp or less. With respect to the average temperature and average dew point, the temperature and dew point measured every 3 hours using the DM70 were averaged to measure the average temperature and average dew point.

[0307] <Method for measuring pressure>

[0308] The pressure inside the tank was measured by visually reading a pressure gauge attached to the tank.

[0309] <Method for measuring water vapor transmission rate of packaging material and core tube>

[0310] Measurement method A: In the case of plastic film, plastic sheet, and multilayer material containing plastic having a thickness of 2 mm or less

[0311] The thickness and water vapor transmission rate of the packaging material were measured in accordance with JIS K7130 and JIS K7129-1. Three measurements were performed for each sample, and the average value thereof was used as the thickness and water vapor transmission rate of the packaging material. Note that the test piece used was one that had no wrinkles, folds, or pinholes and had a uniform thickness when visually observed.

[0312] • Apparatus: Water vapor transmission rate meter L80-5000 (manufactured by Lyssy Corporation · ISO-PE-Z91)

[0313] • Thickness meter: ID-C1012C (manufactured by Mitutoyo · ISO-PE-Z78)

[0314] • Temperature and humidity: 40°C · 90% Rh

[0315] • Measurement area: About 50 cm 2

[0316] • Reference sample: PET 19 μm thickness (25.5 g / (m 2 × 24 hr)

[0317] • Measurement direction: From the side that was the outside when the glass cloth was packaged

[0318] Measurement method B: In the case where the packaging material was other than the object of measurement method A and was other than the core tube

[0319] As for the packaging material other than the subject of Measurement Method A, when the outside of the packaging material is set to a humidity of 90% Rh at a temperature of 40°C and the inside is sealed while keeping the air dry, the weight of water vapor that has penetrated into the inside of the packaging material is measured. The weight of water vapor is expressed in terms of the permeation time per 24 hours and the permeation amount per 1 m 2 The outside surface area of the packaging material is calculated. Specifically, dry air having a dew point of -30°C dp is enclosed in the inside of the packaging material, 800 g of a desiccant of Quality 1A of JIS Z 0701 (desiccant for packaging) or a desiccant of a quality equivalent to or higher than that is added, the temperature and the dew point are measured, and the packaging material is sealed. Here, in the case where 800 g of the desiccant is not added, the measurement is performed in such a manner that the weight of the enclosed desiccant can be known, and the desiccant is enclosed in such a manner that the capacity becomes more than half of the inner volume of the packaging material. Next, the sealed packaging material is put into a constant temperature and humidity device of 40°C • 90% Rh, and the packaging material is stored in the constant temperature and humidity device for an appropriate time of 48 hours or more. After a certain time (the time is referred to as the in-device storage time), the packaging material is taken out of the constant temperature and humidity device, and the temperature and the dew point in the inside of the packaging material and the post-test weight of the desiccant are measured immediately. Note that in the case where the post-test weight of the desiccant exceeds 130% of the enclosed weight of the desiccant, the in-device storage time is shortened, or the amount of the desiccant is increased, or the like, and the measurement is performed again. In addition, the temperature and the dew point measured before the start of the test and after the end of the test are used to calculate the absolute humidity (g / m 3 ) before the start of the test and after the end of the test. Specifically, the temperature and the dew point are input to a VAISALA Humidity Calculator, and the absolute humidity is calculated. The measurement is performed three times for each sample, and the water vapor permeation rate is calculated using the following equation, and the average value thereof is used as the water vapor permeation rate of the packaging material.

[0320] Change in the amount of water vapor in the inside air (g) = {absolute humidity at the end of the test (g / m 3 ) - absolute humidity at the start of the test (g / m 3 )} x inner volume of the packaging material (m 3 )

[0321] Water vapor permeation rate (g / (m 2 x 24 hr) = {post-test weight of the desiccant (g) - enclosed weight of the desiccant (g) + change in the amount of water vapor in the inside air (g)} / {outside surface area of the packaging material (m 2 ) x {in-device storage time (hr) / 24 (hr)}}

[0322] Measurement Method C: In the case of a core tube

[0323] Figure 2 is a schematic diagram for explaining a measurement method of a water vapor permeation rate. As shown inFigure 2 As shown, with respect to the core tube, a film 13 having a known water vapor permeability is wound around the outer surface of the core tube 11, dry air having a dew point of -30°C dp is enclosed in the inside sandwiched by the film and the core tube, 800 g of a hygroscopic agent 16 of a quality of Class 1A of JIS Z 0701 (desiccant for packaging) or a quality equivalent thereto or more is added, a glass cloth package 10 in which the joint 15 between the film and the core tube is sealed with a tape is prepared. In a case where the hygroscopic agent is not added by 800 g, the weight of the enclosed hygroscopic agent is measured in a manner that it can be known, and the hygroscopic agent is enclosed in a capacity of more than half of the inner volume of the packaging material. Then, the water vapor permeability of the packaging material is calculated in the same manner as in <Measurement method of water vapor permeability of packaging material: Measurement method B>. Then, the water vapor permeability of the core tube is calculated from the water vapor permeability of the film wound around the outer surface of the core tube and the surface area thereof by the following equation.

[0324] Water vapor permeability of packaging material (g / (m 2 ×24 hr)) = {water vapor permeability of film (g / (m 2 ×24 hr)) × surface area of film (m 2 ) + water vapor permeability of core tube (g / (m 2 ×24 hr)) × outer diameter side surface area of core tube (m 2 )} / { surface area of film (m 2 ) + outer diameter side surface area of core tube (m 2 )}

[0325] <Change rate of dielectric loss tangent (Df) of glass cloth>

[0326] The change rate of the dielectric loss tangent (Df) of the glass cloth is calculated from the dielectric loss tangent (Df x ) after X days of storage with respect to the dielectric loss tangent (Df0) at the start of storage by the following equation.

[0327] Df change rate (%) = Df x / Df0 × 100

[0328] The smaller the long-term rate of change (rise) in the dielectric loss tangent of the glass cloth at 10 GHz, the greater the effect of maintaining the storage environment of the glass cloth. The rate of change in the dielectric loss tangent of the glass cloth is evaluated using the above equation, and the rate of change in the dielectric loss tangent of the glass cloth 365 days after the start of storage of the glass cloth is preferably 180% or less, more preferably 160% or less, further preferably 140% or less, still further preferably 120% or less, particularly preferably 110% or less. In addition, the rate of change in the dielectric loss tangent of the glass cloth 30 days after the start of storage of the glass cloth is preferably 120% or less, more preferably 115% or less, further preferably 110% or less, particularly preferably 105% or less. If the change in the dielectric loss tangent is within the above range (120% or less after 30 days and 180% or less after 365 days), it is considered that the effect of controlling the storage environment of the glass cloth is obtained. Note that the start of storage is not particularly limited, and a person skilled in the art will take the date on which the glass cloth is stored in a certain environment for a certain period as the start. For example, 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 is taken as the start of storage, and the period until the aforementioned packaged glass cloth is unpacked in the customer process is taken as the storage period.

[0329] <change in dew point>

[0330] The change in dew point in the packaging body having a moisture absorbent inside is calculated by the following equation.

[0331] Change in dew point = (dew point of storage environment after 365 days (°C dp) - initial dew point of storage environment (°C dp)) / (average dew point of external environment of packaging material (°C dp) - dew point of storage environment after 365 days (°C dp))

[0332] In the case where 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, it is taken as unqualified (NG).

[0333] <Method for measuring surface area of packaging material>

[0334] The surface area of the packaging material is calculated from the shape of the state of the packaging body after packaging. As shown in (1c) of FIG. 1, Figure 1 In the case where the glass cloth is sealed with a film and a core tube to be separated from the external environment, the surface area of the packaging material is measured as the surface area of the film-shaped packaging material and the outer diameter side surface area of the core tube, respectively.

[0335] <Moisture absorbent and film>

[0336] <Kind of moisture absorbent>

[0337] • Hygroscopic agent A: ABREON (registered trademark) AW (A-type silica gel) manufactured by Toyota Fine Chemicals Co., Ltd.

[0338] • Hygroscopic agent B: RP agent (calcined diatomaceous earth and calcium oxide) manufactured by Mitsubishi Gas Chemical Co., Inc. (MGC)

[0339] <Kind of film>

[0340] [Table 1]

[0341]

[0342] <Manufacture of glass cloth>

[0343] <Manufacture of Q1035 (raw cloth)>

[0344] A cloth was woven using glass filaments having a SiO2composition of more than 99.9 mass%, using an air jet loom, at a weaving density of 66 warp filaments per 25 mm and 68 weft filaments per 25 mm. Note that weaving was performed in a manner such that the cloth width was 1300 mm. As the warp filaments, glass filaments of silica having an average filament diameter of 5.0 μm, a filament count of 100, and a twist count of 1.0 Z were used. In addition, as the weft filaments, glass filaments of silica having an average filament diameter of 5.0 μm, a filament count of 100, and a twist count of 1.0 Z were used.

[0345] <Manufacture of L1035 (raw cloth) cloth>

[0346] A cloth was woven using glass filaments having a SiO2composition of 53 mass% and a B2O3composition of 23 mass%, using an air jet loom, at a weaving density of 66 warp filaments per 25 mm and 68 weft filaments per 25 mm. Note that weaving was performed in a manner such that the cloth width was 1300 mm. As the warp filaments, glass filaments having an average filament diameter of 5.0 μm, a filament count of 100, and a twist count of 1.0 Z were used. In addition, as the weft filaments, glass filaments having an average filament diameter of 5.0 μm, a filament count of 100, and a twist count of 1.0 Z were used.

[0347] <Examples and Comparative Examples>

[0348] <Example Al>

[0349] The obtained Q1035 base cloth was heated at 600°C for 60 seconds in a heating furnace to perform deoiling (heating deoiling step). Subsequently, a treatment liquid in which 0.15 mass% of 3-methacryloxypropyltrimethoxysilane (silane coupling agent A), Z6030 (manufactured by Dow Toray Co.), and 0.15 mass% of 5-hexenyltrimethoxysilane (silane coupling agent B), Z6161 (manufactured by Dow Toray Co.), were dispersed in pure water adjusted to pH = 3 with acetic acid was prepared. The cloth was dipped in the treatment liquid at a line tension of 200 N and a line speed of 30 m / minute (surface treatment agent coating step), and the liquid was extruded with a rubber roller made of NBR at a pressure of 0.3 MPa, and then dried at 130°C for 60 seconds (drying step) to perform fixation of the silane coupling agent (fixing step). The dried cloth was subjected to high-pressure opening with spraying at a pressure of 2.0 kg / cm 2 After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0350] <Example A2>

[0351] The glass cloth obtained in Example Al was packaged with a bag of film A (thickness 99 μm, water vapor permeability 0.1 g / (m 2 × 24 hr) in an environment at a temperature of 23°C, and a hygroscopic agent A (800 g) was enclosed inside. Further, dry air at a dew point of -20°C dp was enclosed inside to make the dew point -20°C dp, and the opening portion was heat-sealed to seal, whereby a packaged glass cloth was obtained. Then, the packaged glass cloth was moved to an external environment at a temperature of 30°C and a dew point of 24°C dp, and was stored. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0352] <Example A3>

[0353] The obtained Q1035 base cloth was heated at 1000°C for 60 seconds to perform deoiling, and otherwise, a glass cloth was obtained by the same process as in Example Al. The glass cloth was put in a box-shaped packaging material (water vapor permeability 0.0 g / (m 2 × 24 hr) in an environment at a temperature of 23°C and a dew point of 12°C dp. Subsequently, a hygroscopic agent A (800 g) was enclosed inside the packaging body, and stored. After 30 days and 365 days, the glass cloth was taken out and evaluated.

[0354] <Example A4>

[0355] The obtained Q1035 fabric was heated in an intermittent furnace at 370°C for 72 hours to perform a heat degreasing process. A treatment solution containing 0.30% by mass of 3-methacryloyloxypropyltrimethoxysilane (silane coupling agent A) and Z6030 (manufactured by Dow Toray) was prepared. Otherwise, a roll of glass cloth was obtained using the same method as in Example A1. This glass cloth was then subjected to a temperature of 23°C and a dew point of 12°C dp using film A (thickness 99 μm, water vapor transmission rate 0.1 g / (m²)). 2 The glass cloth was packaged in a bag (×24hr) and 800g of desiccant B was sealed inside. The opening was then heat-sealed to obtain the packaged glass cloth. The packaged glass cloth was then placed in an external environment with a temperature of 30°C and a dew point of 24°Cdp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0356] <Example A5>

[0357] The rolled glass cloth obtained in Example A1 was placed in a storage room maintained at a temperature of 25°C and a dew point of 2°C dp using a dehumidifier and stored there. The glass cloth was removed and evaluated after 30 days and 365 days.

[0358] <Example A6>

[0359] The rolled glass cloth obtained in Example A1 was placed in a storage room maintained at a temperature of 25°C and a dew point of 8°C dp using a dehumidifier and stored for evaluation. The glass cloth was removed after 30 days and 365 days.

[0360] <Example A7>

[0361] The rolled glass cloth obtained in Example A1 was placed in a box-shaped packaging material (water vapor transmission rate 0.0 g / (m²)) at a temperature of 30°C and a dew point of 24°C dp. 2 (×24hr)) , using a vacuum pump to depressurize the internal pressure to 10. 3 After Pa, seal and store. At this time (10 3 The dew point inside the box-shaped packaging material (Pa) is -32°C dp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0362] <Example A8>

[0363] The rolled glass cloth obtained in Example A1 was subjected to an environment with a temperature of 23°C and a dew point of 12°C dp, and then subjected to a film B (thickness 116 μm, water vapor transmission rate 0.2 g / (m²)). 2The glass cloth obtained in Example Al was packaged in a bag of film C (thickness 78 μm, moisture permeability 6.6 g / (m2-24 hr)) with a desiccant A (8000 g) enclosed inside. Further, the opening was heat-sealed to obtain a packaged glass cloth. Then, the packaged glass cloth was moved to an external environment of temperature 30°C and dew point 24°C dp, and stored. The glass cloth was taken out after 30 days and 365 days, and evaluated.

[0364] <Example A9>

[0365] The glass cloth obtained in Example Al was packaged in a bag of film C (thickness 78 μm, moisture permeability 6.6 g / (m 2 The glass cloth obtained in Example Al was packaged in a bag of film C (thickness 78 μm, moisture permeability 6.6 g / (m

[0366] <Example A10>

[0367] The glass cloth obtained in Example Al was placed in a storage chamber maintained at temperature 45°C and dew point -2°C dp by circulating dry air of -2°C dp, and stored. The glass cloth was taken out after 30 days and 365 days, and evaluated.

[0368] <Example Al l>

[0369] The glass cloth obtained in Example Al was placed in a storage chamber maintained at temperature 23°C and dew point -30°C dp by circulating dry air of -30°C dp, and stored. The glass cloth was taken out after 30 days and 365 days, and evaluated.

[0370] <Comparative Example Al>

[0371] The glass cloth obtained in Example Al was placed in a storage chamber maintained at temperature 30°C and dew point 24°C dp, and stored. The glass cloth was taken out after 30 days and 365 days, and evaluated.

[0372] <Reference Example A>

[0373] The obtained L1035 fabric was heated in an intermittent furnace at 370°C for 72 hours for a heat degreasing process. Otherwise, a roll of glass cloth was obtained using the same method as in Example A1. The glass cloth was then stored in a storage room maintained at 30°C and a dew point of 24°C dp. The glass cloth was removed and evaluated after 30 days and 365 days.

[0374] <Comparative Example A2>

[0375] The rolled glass cloth obtained in Example A3 was placed in a storage room maintained at a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0376] <Comparative Example A3>

[0377] The rolled glass cloth obtained in Example A4 was placed in a storage room maintained at a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0378] <Comparative Example A4>

[0379] The rolled glass cloth obtained in Example A1 was placed in a storage room maintained at a temperature of 40°C and a dew point of 38°C dp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0380] <Comparative Example A5>

[0381] The rolled glass cloth obtained in Example A1 was subjected to an environment with a temperature of 23°C and a dew point of 12°C dp, and then subjected to a film D (thickness 45 μm, water vapor transmission rate 11 g / (m²)). 2 The glass cloth was packaged in a bag (24 hours) and 8000g of desiccant A was sealed inside. The opening was then heat-sealed to obtain the packaged glass cloth. The packaged glass cloth was then placed in an external environment with a temperature of 30°C and a dew point of 24°Cdp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0382] <Comparative Example A6>

[0383] The rolled glass cloth obtained in Example A11 was placed in a storage room maintained at a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0384] The manufacturing conditions and evaluation results for Examples A1-A11, Comparative Examples A1-A6, and Reference Example A are shown in the table below.

[0385] [Table 2]

[0386]

[0387] [Table 3]

[0388]

[0389] In Example Al, the dielectric loss tangent of the glass cloth did not change after long-term storage (after 30 days and after 365 days), in contrast to which, in Comparative Example Al, the dielectric loss tangent of the glass cloth increased greatly. On the other hand, in Reference Example A in which the dielectric loss tangent of the glass cloth was higher than 0.00200, an increase in the dielectric loss tangent was not observed even under the same storage environment as in Comparative Example Al. In Comparative Example A5, the water vapor permeability of the bag in which the glass cloth was packed was high, and thus the amount of moisture inflow was large, and it was difficult to sufficiently lower the dew point inside even if a moisture absorbent was used.

[0390] Moisture Absorbents and Packaging Materials

[0391] Types of Moisture Absorbents

[0392] • Moisture Absorbent A: ABREON (registered trademark) AW (A-type silica gel) manufactured by Toyota Fine Chemicals Co., Ltd.

[0393] • Moisture Absorbent B: RP agent (calcined diatomaceous earth and calcium oxide) manufactured by Mitsubishi Gas Chemical Co., Inc. (MGC)

[0394] Types of Packaging Materials

[0395] [Table 4]

[0396]

[0397] Manufacture of Glass Cloth

[0398] Manufacture of Q1035 (Raw Cloth)

[0399] A glass cloth was woven using a glass yarn having a SiO2composition of more than 99.9 mass%, using an air jet loom, at a weaving density of 66 warp yarns / 25 mm and 68 weft yarns / 25 mm. Note that weaving was performed in a manner such that the cloth width was 1300 mm. As the warp yarns, a silica glass yarn having an average filament diameter of 5.0 μm, a filament count of 100, and a twist count of 1.0 Z was used. In addition, as the weft yarns, a silica glass yarn having an average filament diameter of 5.0 μm, a filament count of 100, and a twist count of 1.0 Z was used.

[0400] Manufacture of L1035 (Raw Cloth) Cloth

[0401] The fabric was woven using glass fibers with a SiO2 composition of 53% by mass and a B2O3 composition of 23% by mass on an air-jet loom, with a weaving density of 66 warp threads / 25mm and 68 weft threads / 25mm. It should be noted that the fabric was woven with a width of 1300mm. The warp threads were glass fibers with an average filament diameter of 5.0μm, 100 filaments, and a twist count of 1.0Z. Similarly, the weft threads were glass fibers with an average filament diameter of 5.0μm, 100 filaments, and a twist count of 1.0Z.

[0402] Examples and Comparative Examples

[0403] <Example B1>

[0404] The obtained Q1035 fabric was heated in a furnace at 600°C for 60 seconds to remove oil (heating degreasing process). Next, a treatment solution was prepared, containing 0.15% by mass of 3-methacryloyloxypropyltrimethoxysilane (silane coupling agent A); Z6030 (manufactured by Dow Toray) and 0.15% by mass of 5-hexenyltrimethoxysilane (silane coupling agent B); Z6161 (manufactured by Dow Toray) dispersed in pure water adjusted to pH=3 with acetic acid. The fabric was immersed in the treatment solution at a linear tension of 200 N and a linear speed of 30 m / min (surface treatment agent coating process). After extruding the liquid using an NBR rubber roller at a pressure of 0.3 MPa, it was dried at 130°C for 60 seconds to fix the silane coupling agent (fixing process). The dried fabric was then sprayed with 2.0 kg / cm² water. 2 The fiber is opened under high pressure and then dried at 130°C for 1 minute (drying process). It is then wound into a core tube with a hollow part to obtain a roll of glass cloth.

[0405] The glass cloth was subjected to a temperature of 23℃ and then packaged with packaging material A (aluminum laminate film, 99μm thick, water vapor transmission rate 0.1g / (m²)). 2 The glass cloth is packaged for 24 hours and sealed with 800g of desiccant A inside. Then, dry air with a dew point of -20°C dp is sealed inside to achieve a dew point of -20°C dp. The opening is then heat-pressed to seal, thus obtaining the glass cloth package. The glass cloth package is then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth is removed and evaluated after 30 days and 365 days.

[0406] <Example B2>

[0407] The obtained Q1035 fabric was heated at 1000°C for 60 seconds to remove oil. Otherwise, it was processed in the same way as in Example B1 to obtain a roll of glass cloth. This glass cloth was then placed in a packaging material F (a stainless steel box with a water vapor transmission rate of 0.0 g / (m²)) at a temperature of 23°C and a dew point of 12°C dp. 2 The process involves placing a desiccant A (800g) inside the packaging material for 24 hours. Then, the material is sealed to create a glass cloth package. The glass cloth package is then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth is then removed and evaluated after 30 days and 365 days.

[0408] <Example B3>

[0409] The obtained Q1035 fabric was heated in an intermittent furnace at 370°C for 72 hours to perform a heat degreasing process. A treatment solution containing 0.30% by mass of 3-methacryloyloxypropyltrimethoxysilane (silane coupling agent A) and Z6030 (manufactured by Dow Toray) was prepared. Otherwise, rolls of glass cloth were obtained using the same method as in Example B1. This glass cloth was then subjected to a temperature of 23°C and a dew point of 12°C dp using packaging material A (aluminum laminate film, 99 μm thick, water vapor transmission rate 0.1 g / (m²)). 2 The glass cloth was packaged for 24 hours and sealed with 800g of desiccant B inside. The opening was then heat-sealed to obtain the glass cloth package. The package was then placed in an external environment at 30°C and a dew point of 24°C dp for storage. The glass cloth was evaluated after 30 days and 365 days.

[0410] <Example B4>

[0411] The rolled glass cloth obtained in Example B1 was subjected to a temperature of 23°C and then coated with packaging material B (ceramic vapor-deposited film, 116 μm thick, water vapor permeability 0.2 g / (m²)). 2 The glass cloth is packaged for 24 hours and sealed with 800g of desiccant A inside. Then, dry air with a dew point of -20°C dp is sealed inside to achieve a dew point of -20°C dp. The opening is then heat-pressed to seal, thus obtaining the glass cloth package. The glass cloth package is then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth is removed and evaluated after 30 days and 365 days.

[0412] <Example B5>

[0413] The rolled glass cloth obtained in Example B1 was subjected to an environment of 23°C and a dew point of 12°C dp using packaging material C (ceramic vapor-deposited film, thickness 115 μm, water vapor transmission rate 1.5 g / (m²)).2 The glass cloth was packaged for 24 hours, with 8000g of desiccant A inside, and the opening was heat-sealed to obtain the glass cloth package. The glass cloth package was then placed in an external environment with a temperature of 30°C and a dew point of 24°Cdp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0414] <Example B6>

[0415] The rolled glass cloth obtained in Example B1 was subjected to an environment of 23°C and a dew point of 12°C dp using packaging material D (ceramic vapor-deposited film, 78 μm thick, water vapor transmission rate 6.6 g / (m²)). 2 The glass cloth was packaged for 24 hours and sealed with 8000g of desiccant A inside. The opening was then heat-sealed to obtain the glass cloth package. The package was then placed in an external environment at 30°C and a dew point of 24°C dp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0416] <Example B7>

[0417] The rolled glass cloth obtained in Example B1 was placed in a packaging material F (a stainless steel box with a water vapor transmission rate of 0.0 g / (m²)) at a temperature of 30°C and a dew point of 24°C dp. 2 During the 24-hour period, a vacuum pump is used to depressurize the internal pressure to 10. 3 After Pa, it is sealed to form a glass cloth packaging. At this time (10 3 The dew point inside the glass cloth packaging (Pa) was -32℃dp. The glass cloth packaging was then moved to an external environment with a temperature of 30℃ and a dew point of 24℃dp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0418] <Example B8>

[0419] The obtained Q1035 fabric was heated in a furnace at 600℃ for 60 seconds to remove oil (heating degreasing process), and then wound into a core tube with a hollow section, thus obtaining a roll of glass cloth. This glass cloth was then subjected to a temperature of 23℃ and packaged with packaging material A (aluminum laminate film, 99μm thick, water vapor transmission rate 0.1g / (m²)). 2 The glass cloth is packaged for 24 hours and sealed with 800g of desiccant A inside. Then, dry air with a dew point of -20°C dp is sealed inside to achieve a dew point of -20°C dp. The opening is then heat-pressed to seal, thus obtaining the glass cloth package. The glass cloth package is then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth is removed and evaluated after 30 days and 365 days.

[0420] <Comparative Example B1>

[0421] The rolled glass cloth obtained in Example B1 was placed in an environment with a temperature of 23°C and a dew point of 12°C dp using packaging material E (polyethylene film, thickness 45 μm, moisture permeability 11 g / (m²)). 2 The glass cloth was packaged for 24 hours and sealed with 8000g of desiccant A inside. The opening was then heat-sealed to obtain the glass cloth package. The package was then placed in an external environment at 30°C and a dew point of 24°C dp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0422] <Reference Example B>

[0423] The obtained L1035 fabric was heated in an intermittent furnace at 370°C for 72 hours for a heat degreasing process. Otherwise, a roll of glass cloth was obtained using the same method as in Example B1. This glass cloth was then packaged with packaging material E (polyethylene film, 45 μm thick, moisture permeability 11 g / (m²)) at a temperature of 23°C and a dew point of 12°C dp. 2 The glass cloth was packaged for 24 hours and sealed with 8000g of desiccant A inside. The opening was then heat-sealed to obtain the glass cloth package. The package was then placed in an external environment at 30°C and a dew point of 24°C dp for storage. The glass cloth was removed and evaluated after 30 days and 365 days.

[0424] <Comparative Example B2>

[0425] The rolled glass cloth obtained in Example B2 was placed in packaging material G (corrugated cardboard box, water vapor transmission rate 50 g / (m²)) at a temperature of 23°C and a dew point of 12°C dp. 2 The process involves placing a desiccant A (8000g) inside the packaging for 24 hours. Then, the packaging is sealed to create a glass cloth package. The glass cloth package is then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth is then removed and evaluated after 30 days and 365 days.

[0426] <Comparative Example B3>

[0427] The rolled glass cloth obtained in Example B3 was placed in packaging material G (corrugated cardboard box, water vapor transmission rate 50 g / (m²)) at a temperature of 23°C and a dew point of 12°C dp. 2 The glass cloth is sealed and packaged for 24 hours. Then, the glass cloth package is placed in an external environment with a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth is removed and evaluated after 30 days and 365 days.

[0428] <Comparative Example B4>

[0429] The glass cloth obtained in Example B8 was packaged with packaging material E (polyethylene film, thickness 45 μm, moisture permeability 11 g / (m 2 × 24 hr) in an environment of temperature 23°C and dew point 12°C dp, and the opening portion was heat-sealed to seal, thereby obtaining a glass cloth package. Then, the glass cloth package was moved to an external environment of temperature 30°C and dew point 24°C dp, and was stored. The glass cloth was taken out after 30 days and after 365 days, and was evaluated.

[0430] The manufacturing conditions and evaluation results with respect to Examples B1 to B8, Comparative Examples B1 to B4, and Reference Example B are shown in the following table.

[0431] [Table 5]

[0432]

[0433] [Table 6]

[0434]

[0435] In Example B1, the dielectric loss tangent of the glass cloth after long-term storage (after 30 days and after 365 days) did not change, in contrast to which, in Comparative Example B1, the dielectric loss tangent of the glass cloth increased greatly. In Comparative Example B1, the water vapor permeability of the bag in which the glass cloth was packaged was high, and thus the amount of moisture inflow was large, and even if a moisture absorbent was used, it was difficult to sufficiently lower the internal dew point. On the other hand, in Reference Example B in which the dielectric loss tangent of the glass cloth was higher than 0.00200, an increase in the dielectric loss tangent was not observed even in the same storage environment as Comparative Example B1.

[0436] <Kind of Core Tube>

[0437] [Table 7]

[0438]

[0439] <Example B9>

[0440] The glass cloth obtained in Example B1 was packaged with packaging material A (aluminum laminated film, thickness 99 μm, water vapor permeability 0.1 g / (m 2The packaging material is packaged for 24 hours and contains 800g of desiccant A. Dry air with a dew point of -20°C dp is then sealed inside the packaging material A. The opening is then heat-pressed to seal the package while maintaining a dew point of -20°C dp. The remaining packaging material on one side is pressed into the hollow portion of the core tube, resulting in a glass cloth package with a recess extending from one end of the core tube into the inner side of the hollow portion. The surface area of ​​packaging material A is 3.5m². 2 The volume of the hollow portion of the core tube that becomes the internal space of the packaging body accounts for 20% of the total volume. The glass cloth packaging body is then moved to an external environment with a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth is removed and evaluated after 30 days and 365 days.

[0441] <Example B10>

[0442] The rolled glass cloth obtained in Example B1 was subjected to packaging material A (aluminum laminate film, 99 μm thick, water vapor transmission rate 0.1 g / (m²)) at a temperature of 23°C. 2 (×24hr)) Packaging, with desiccant A (800g) sealed inside. Inside a core tube with a roll of glass cloth, a tubular packaging material A is inserted along its inner wall. Dry air with a dew point of -20°C dp is sealed inside the packaging material A covering the outer surface of the roll. With the dew point set to -20°C dp, the packaging material A covering the outer surface of the roll is heat-pressed to the tubular packaging material A penetrating the inner diameter of the core tube, sealing the opening to obtain an annular glass cloth package with an external environment permeable to the hollow section. At this point, the surface area of ​​packaging material A is 3.0 m². 2 The volume of the hollow portion of the core tube that becomes the internal space of the packaging body accounts for 5% of the total volume. Then, the glass cloth packaging body is moved to an external environment with a temperature of 30°C and a dew point of 24°C dp for storage. The glass cloth is removed and evaluated after 30 days and 365 days.

[0443] <Example B11>

[0444] The obtained glass cloth was rolled up with a water vapor transmission rate of 0.1 g / (m). 2 A core tube H made of FRP (24hr × 10 ... 2 The packaging material is packaged for 24 hours and contains 800g of desiccant A. Dry air with a dew point of -20°C dp is then sealed inside the packaging material A. The opening is then sealed with moisture-proof tape to the exposed outer surface of the core tube, thus obtaining the glass cloth packaging. At this point, the surface area of ​​packaging material A is 2.0 m².2 the outer diameter side surface area of the core pipe was 1.0 m2 2 the volume of the space inside the core pipe that became the inside of the package was 0%. Then, the glass cloth package was moved to an external environment of 30°C in temperature and 24°C dp in dew point, and was stored. The glass cloth was taken out after 30 days and 365 days, and was evaluated.

[0445] <Example B12>

[0446] The obtained glass cloth was wound on a core pipe I made of FRP having a water vapor permeability of 1.0 g / (m 2 × 24 hr), and a glass cloth in a roll was obtained in the same manner as in Example Bl, except that. The glass cloth in a roll was wrapped with a wrapping material A (aluminum laminated film, thickness 99 μm, water vapor permeability 0.1 g / (m 2 × 24 hr) in an environment of 23°C in temperature, and a desiccant A (1200 g) was enclosed inside. The film of the opening portion was adhered to the exposed outer surface of the core pipe and was sealed with a moisture-proof sealing tape, and a glass cloth package was obtained in a state where the inside of the wrapping material A was set to -20°C dp by enclosing dry air of -20°C dp. At this time, the surface area of the wrapping material A was 2.0 m 2 the outer diameter side surface area of the core pipe was 1.0 m2 2 the volume of the space inside the core pipe that became the inside of the package was 0%. Then, the glass cloth package was moved to an external environment of 30°C in temperature and 24°C dp in dew point, and was stored. The glass cloth was taken out after 30 days and 365 days, and was evaluated.

[0447] <Comparative Example B5>

[0448] The obtained glass cloth was wound on a core pipe J made of paper having a water vapor permeability of 9.6 g / (m 2 × 24 hr), and a glass cloth in a roll was obtained in the same manner as in Example Bl, except that. The glass cloth in a roll was wrapped with a wrapping material E (polyethylene film, thickness 45 μm, moisture permeability 11 g / (m 2 × 24 hr) in an environment of 23°C in temperature and 12°C dp in dew point, and a desiccant A (8000 g) was enclosed inside. The film of the opening portion was adhered to the core pipe and was sealed with a moisture-proof sealing tape, and a glass cloth package was obtained. At this time, the surface area of the wrapping material E was 1.8 m 2 the outer diameter side surface area of the core pipe was 0.8 m2 2 the volume of the space inside the core pipe that became the inside of the package was 0%. Then, the glass cloth package was moved to an external environment of 30°C in temperature and 24°C dp in dew point, and was stored. The glass cloth was taken out after 30 days and 365 days, and was evaluated.

[0449] The manufacturing conditions and evaluation results regarding Examples B9 to B12 and Comparative Example B5 are shown in the following table.

[0450] [Table 8]

[0451]

[0452] In Examples B1 to B12, the dielectric loss tangent of the glass cloth did not change after long-term storage (after 30 days and after 365 days), in contrast to which, in Comparative Example B5, the dielectric loss tangent of the glass cloth increased greatly.

[0453] Explanation of Reference Signs

[0454] 10 Glass cloth package

[0455] 11 Core tube

[0456] 12 Glass cloth

[0457] 13 Film

[0458] 13a Outer film

[0459] 13b Inner film

[0460] 14 Concave portion

[0461] 15 Joint portion

[0462] 16 Moisture absorbent

Claims

1. A method for storing a glass cloth, wherein, The glass cloth is composed of glass filaments including a plurality of filaments as warp and weft, and has a dielectric loss tangent of 0.00200 or less at 10 GHz, The method includes storing the glass cloth in an atmosphere having an average dew point of 18°Cdp or less and an average temperature of 100°C or less at the air pressure of a storage environment.

2. The method of claim 1, wherein, The content of silicon (Si) in the glass filaments is 95.0 to 100 mass% as silicon dioxide (SiO2).

3. The method of claim 1 or 2, wherein, The glass cloth has a surface treatment agent including a silane coupling agent on a surface thereof.

4. The method of claim 3, wherein, The surface treatment agent includes 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 including at least one of an amino group and an unsaturated double bond group having radical reactivity, Y is each independently an alkoxy group, n is an integer of 1 or more and 3 or less, and R is each independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.

5. The method of claim 4, wherein, The surface treatment agent includes two or more kinds of silane coupling agents different in X in the formula (1).

6. The method of claim 3, wherein, The surface treatment agent includes two or more kinds of silane coupling agents different in molecular weight.

7. The method of claim 3, wherein, The method further includes, before the storing, a step of surface-treating the glass cloth with a surface treatment agent including a silane coupling agent, and a step of opening the glass cloth subjected to the surface treatment.

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

9. The method of claim 1 or 2, wherein, The glass cloth has a beat-in density of the warp and / or weft filaments in the range of 66 to 120 filaments / inch (= 66 to 120 filaments / 25 mm).

10. The method of claim 1 or 2, wherein, The method further includes, before the storing, a step of heating the glass cloth while transporting the glass cloth in a roll-to-roll manner at a temperature of 600°C or more.

11. The method of claim 1 or 2, wherein, The glass cloth is stored in the form of a package in which the glass cloth is wrapped with a packaging material in a box and / or a film shape.

12. The method of claim 11, wherein, The glass cloth is stored in the form of a package in which the glass cloth is wrapped with a packaging material in a film shape, the packaging material in the film shape having a thickness of 50 μm or more.

13. The method of claim 11, wherein, The glass cloth is stored in the form of a package in which the glass cloth is wrapped with a packaging material in a film shape, the packaging material in the film shape being an aluminum laminated film.

14. The method of claim 11, wherein, The glass cloth is stored in the form of a package in which the glass cloth is wrapped with a packaging material in a film shape in a state of being wound on a roll of a hollow cylindrical core pipe, the packaging material in the film shape having a recess extending into a hollow portion from one end or both ends of the core pipe, or the packaging material in the film shape being a torus shape penetrating the hollow portion of the core pipe.

15. The method of claim 14, wherein, A proportion of a volume of a space inside the packaging material in the film shape to a volume of the hollow portion of the core pipe is 50% or less of the volume of the hollow portion of the core pipe.

16. The method of claim 14, wherein, The packaging material in the film shape is a torus shape penetrating the hollow portion of the core pipe.

17. The method of claim 14, wherein, The package is configured such that the glass cloth is sealed from an external environment by the packaging material in the film shape and the core pipe.

18. The method of claim 14, wherein, The water vapor transmission rate of the core tube is 8 g / (m 2 × 24 hr) or less at 40°C under 90% Rh.

19. The method of claim 11, wherein, The water vapor transmission rate of the packaging material is 8 g / (m 2 × 24 hr) or less at a measurement temperature of 40°C and a measurement humidity of 90% Rh.

20. The method of claim 11, wherein, The package is configured such that the inside thereof is dehumidified in a manner to maintain an average dew point at 18°Cdp or less.

21. The method of claim 1 or 2, comprising: The storage is performed under conditions that the average dew point under the air pressure of the storage environment is 13°Cdp or more and 18°Cdp or less.

22. The method of claim 1 or 2, comprising: The storage is performed under conditions that the average dew point under the air pressure of the storage environment is -21°Cdp or less.

23. The method of claim 11, wherein, The packaging body has a desiccant therein.

24. The method of claim 23, wherein, The amount of the desiccant enclosed satisfies the following formula (2): WVTR x packaging body surface area / desiccant enclosed amount ≤ 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, the unit of which is g / (m 2 × 24 hr), the unit of the surface area of the packaging body is m 2 , and the unit of the moisture absorbent enclosed amount is g.

25. The method of claim 23, wherein, The desiccant is at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, baked diatomaceous earth, synthetic zeolite, clay-based desiccant, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate.

26. The method of claim 23, wherein, The desiccant is a sheet-shaped desiccant.

27. The method of claim 1 or 2, wherein, The atmosphere is dry air having an average dew point of 18°Cdp or less, or a gas containing at least one selected from the group consisting of nitrogen, argon, and oxygen, having an average dew point of 18°Cdp or less.

28. The method of claim 1 or 2, wherein, The atmosphere is reduced to less than the atmospheric pressure.

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

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

31. A glass cloth packaging body comprising: a packaging material, and a glass cloth housed in the inside of the packaging material, The glass cloth is constituted with glass filaments including a plurality of filaments as warp and weft, The glass cloth has a dielectric loss tangent of 0.00200 or less at 10 GHz, The packaging material is sealed, The water vapor transmission rate of the packaging material is 8 g / (m 2 × 24 hr) or less at 40°C under 90% Rh.

32. The glass cloth package of claim 31, wherein, The packaging material is a box and / or a film.

33. The glass cloth package of claim 32, wherein, The packaging material is a film, and the film has a thickness of 50 μm or more.

34. The glass cloth package of claim 32, wherein, The packaging material is a film, and the film is an aluminum laminated film.

35. The glass cloth package of claim 32, wherein, The glass cloth is packaged with a film in a state of a roll wound around a core pipe of a hollow columnar shape, the film has a recess portion extending into the hollow portion from one end or both ends of the core pipe, or the film is a torus shape penetrating the hollow portion of the core pipe.

36. The glass cloth package of claim 35, wherein, The proportion of the space inside the film to the hollow portion volume of the core pipe is 50% or less of the hollow portion volume of the core pipe.

37. The glass cloth package of claim 35, wherein, The film is a torus shape penetrating the hollow portion of the core pipe.

38. The glass cloth package of claim 35, wherein, The packaging body is configured such that the glass cloth is sealed from the outside environment by the film and the core pipe.

39. The glass cloth package of claim 35, wherein, The water vapor transmission rate of the core tube is 8 g / (m 2 × 24 hr) or less at 40°C under 90% Rh.

40. The glass cloth package of claim 31 or 32, wherein, The dew point inside the packaging material is 18°Cdp or less.

41. The glass cloth package of claim 31 or 32, wherein, The dew point inside the packaging material is 13°Cdp or more and 18°Cdp or less.

42. The glass cloth package of claim 31 or 32, wherein, The dew point inside the packaging material is -21°Cdp or less.

43. The glass cloth package of claim 31 or 32, wherein, The glass cloth is in a state of a roll.

44. The glass cloth package of claim 31 or 32, wherein, A desiccant is enclosed in the inside of the packaging material.

45. The glass cloth package of claim 44, wherein, The amount of the desiccant enclosed satisfies the following formula (2): WVTR x packaging body surface area / desiccant enclosed amount ≤ 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, the unit of which is g / (m 2 × 24 hr), the unit of the surface area of the packaging body is m 2 , and the unit of the moisture absorbent enclosed amount is g.

46. The glass cloth package of claim 44, wherein, The desiccant is at least one selected from the group consisting of silica gel, calcium oxide, calcium chloride, baked diatomaceous earth, synthetic zeolite, clay-based desiccant, phosphorus pentoxide, magnesium sulfate, copper sulfate, magnesium chloride, cobalt chloride, granular soda lime, and magnesium perchlorate.

47. The glass cloth package of claim 44, wherein, The desiccant is a sheet.

48. The glass cloth package of claim 31 or 32, wherein, The inside of the packaging material is filled with dry air having a dew point of 18°Cdp or less, or a gas containing at least one selected from the group consisting of nitrogen, argon, and oxygen, having a dew point of 18°Cdp or less.

49. The glass cloth package of claim 31 or 32, wherein, The inside of the packaging material is reduced to less than the atmospheric pressure.

50. The glass cloth package of claim 31 or 32, wherein, The silicon (Si) content in the glass yarn is 95.0 to 100 mass% as converted into silicon dioxide (SiO2).

51. The glass cloth package of claim 31 or 32, wherein, The glass cloth is treated with a surface treatment agent containing a silane coupling agent.

52. The glass cloth package of claim 51, wherein, The surface treatment agent contains the 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 containing at least one of an amino group and an unsaturated double bond group having radical reactivity, Y is each independently an alkoxy group, n is an integer of 1 or more and 3 or less, and R is each independently a group selected from the group consisting of a methyl group, an ethyl group, and a phenyl group.

53. The glass cloth package of claim 52, wherein, The surface treatment agent contains two or more kinds of silane coupling agents different in X in the formula (1).

54. The glass cloth package of claim 51, wherein, The surface treatment agent contains two or more kinds of silane coupling agents different in molecular weight.

55. The glass cloth package of claim 31 or 32, wherein, The glass cloth has a dielectric loss tangent at 10 GHz of 0.00051 or more and 0.00200 or less.

56. The glass cloth package of claim 31 or 32, wherein, The glass cloth has a pick density of warp and / or weft threads in the range of 66 to 120 threads / inch (= 66 to 120 threads / 25 mm).

57. The glass cloth package of claim 31 or 32, wherein, The unit area weight (mass of the glass cloth) of the glass cloth is 8 to 25 g / m 2 in the range.

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