Glass cloth spreading method

Abstract

To provide a fiber opening method capable of producing a glass cloth having excellent surface smoothness with suppressed fluff caused by wrinkles or broken filaments and sufficient and uniform fiber opening of weft and warp threads, and glass cloth being excellent in uniform resin impregnation with less basket holes.SOLUTION: A fiber opening method of glass cloth comprises spraying a gas-liquid mixture mist, which is prepared by mixing a gas with a liquid to micronize the liquid, on the glass cloth, with a volume ratio of gas consumption V1 to liquid spray amount V2, i.e., V1 / V2, in a range of 5 to 150.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for spreading a spread silica glass cloth. [Background technology]

[0002] It is known that glass fiber woven fabrics are subjected to an opening treatment in order to improve the resin impregnation and surface smoothness of glass cloth, which is mainly used as a laminate for printed wiring boards. A method using ultrasonic waves has been disclosed as a method for this opening treatment. Patent Documents 1 and 2 specifically describe opening treatment of glass cloth by ultrasonic treatment.

[0003] Patent Document 3 describes a method in which a high-pressure water jet is sprayed onto a glass cloth to open glass filaments with high concentration. This conventional method uses a small diameter of about 0.1 to 0.2 mm and a pressure of 4.9 to 14.7 MPa (50 to 150 kg / cm). 2 ) is sprayed onto the glass cloth in a high-pressure columnar water jet, which separates and opens the glass filaments at the joints, allowing them to be impregnated with resin well.

[0004] With the recent trend toward miniaturization of electronic devices, there has been an increasing demand for thinner laminates. To achieve this, glass cloth, which has a low mass and a low thickness, is used. Furthermore, it is preferable that the glass fiber yarns in such glass cloth be widened, the glass fibers be uniformly distributed throughout the laminate, and the glass cloth be smooth. Furthermore, as printed wiring boards become denser and thinner, CAF (Conductive Anodic Filament: copper migration) in printed wiring boards becomes a problem. Therefore, it is necessary to further improve the resin impregnation property to improve CAF resistance. In these respects, further improvements in the above-mentioned fiber-spreading technology are highly desirable.

[0005] When continuous ultrasonic treatment is used to open a long fiber woven fabric such as glass cloth as in Patent Documents 1 and 2, ultrasonic waves are generally applied to the glass cloth while it is running through a medium. Therefore, the opening process is performed in a state where tension acts in the running direction (warp direction) while almost no tension acts in the width direction (weft direction). Therefore, the method of immersing a long fiber woven fabric such as glass cloth in a medium has the problem that wrinkles are likely to occur due to distortion caused by the weft threads shrinking in the width direction.

[0006] Furthermore, with the fiber-opening method using ultrasound, it is difficult to achieve uniform fiber-opening processing for reasons such as the fact that ultrasound is a compressional wave and the strength of the pressure acting on it varies depending on the location in the medium, and that the propagation of ultrasound is hindered in areas where bubbles generated from dissolved air in the medium are present.

[0007] The ultrasonic fiber-opening method described above has the problem that it is difficult to adjust the degree of fiber-opening to match the resin to be impregnated, and there is also the problem that thin cloth is prone to bending and filament breakage. If bending occurs, it may lead to uneven resin impregnation and reduced insulation reliability.

[0008] In the glass cloth spreading method using a high-pressure water columnar jet described in Patent Document 3, the high-pressure water columnar jet is sprayed onto the glass cloth, which causes problems such as roughening of the weave of the glass cloth and damage to some of the glass filaments, resulting in increased generation of fluff. This fluffing is likely to cause irregularities on the surface of the prepreg, and in the case of a printed wiring board, this could damage the copper foil overlying the prepreg, resulting in circuit defects. Furthermore, this method requires a high jetting pressure and requires drying to remove moisture after treatment, which results in high energy and equipment costs, and there is also the risk of the glass filaments re-adhering to each other during drying.

[0009] Patent Document 4 describes a method of spreading fibers by spraying a diffusion spray into the atmosphere. This spreading method by spraying water has almost no spreading effect on the warp yarns, so the warp yarns are not sufficiently spread. Furthermore, the detailed conditions for the spraying method that fully meet the recently required spreading technology are not described, so it could not be used as a method for high-spreading technology.

[0010] As explained above, these conventional opening processes have had the problem that the tension applied to the warp yarns during the process causes the warp yarns to bunch up, making it difficult to open them. Furthermore, there has been a problem that the warp yarns are not opened sufficiently, making it impossible to sufficiently thin the glass cloth. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-241515 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-070325 [Patent Document 3] Japanese Patent Application Publication No. 08-127959 [Patent Document 4] Japanese Patent Application Laid-Open No. 2003-171864 Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention has been made in view of the above problems, and has as its object to provide a fiber-spreading method which can suppress fluffing due to wrinkles and broken glass filaments, can sufficiently and uniformly spread weft and warp yarns, and can produce glass cloth which has good surface smoothness, few basket holes, and excellent uniform resin impregnation. [Means for solving the problem]

[0013] As a result of extensive research to achieve the above object, the present inventors have found that using a gas-liquid mixed mist with an adjusted air-water volume ratio is suitable for achieving high-spreading of glass cloth. That is, by setting the air-water volume ratio to 10 to 150, efficient spreading can be achieved while suppressing strand misalignment and fuzzing. That is, the present inventors have found that it is possible to provide a fiber-spreading method for producing spread silica glass cloth that has a high warp occupancy rate, sufficient warp spreading, a small standard deviation of air permeability, excellent uniform surface smoothness, low air permeability, high warp and weft occupancy rates, and excellent resin impregnation, thereby solving the above problems and leading to the completion of the present invention.

[0014] Therefore, the present invention provides the following method for spreading glass cloth. 1. A method for spreading glass cloth, comprising the steps of mixing a liquid and a gas so that the gas-water volume ratio V1 / V2 of the gas consumption amount V1 and the liquid spray amount V2 is in the range of 5 to 150, spraying the gas-liquid mixed mist into which the liquid has been atomized onto the glass cloth, and spreading the glass cloth. 2. The method for spreading glass cloth according to 1, wherein the atomized gas-liquid mixed mist has an average particle size of 5 to 500 μm. 3. The method for spreading glass cloth according to 1 or 2, wherein the gas-liquid mixed mist is a mixture in which the sum P1+P2 of the gas pressure P1 and the liquid pressure P2 is 0.2 to 2.0 MPa and the pressure ratio P1 / P2 is 0.2 to 1.5. 4. The method for spreading a glass cloth according to any one of 1 to 3, wherein the temperature of the liquid to be mixed is 20 to 90°C. 5. The method for spreading glass cloth according to any one of 1 to 4, wherein the liquid to be mixed is water or a liquid obtained by blending water with one or more selected from alcohol, surfactants, silane coupling agents, lubricants, and colloidal silica. 6. The method for spreading a glass cloth according to any one of 1 to 5, wherein the gas to be mixed is at least one gas selected from air, nitrogen gas and an inert gas. 7. The method for spreading a glass cloth according to any one of 1 to 6, wherein the thickness of the glass cloth is 5 to 100 μm. [Effects of the Invention]

[0015] According to the present invention, by adjusting the air-water volume ratio of the gas-liquid mixed mist and spraying it onto a glass cloth, a glass cloth having excellent surface smoothness and in which both the warp and weft yarns are sufficiently opened, with few basket holes and excellent uniform resin impregnation can be obtained. A prepreg using this glass cloth suppresses the generation of pinholes, has excellent adhesion and cohesion with copper foil, and provides a glass cloth suitable for stable substrates with little transmission loss and no variation. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a cross-sectional schematic view showing an example of a spray nozzle used in the glass cloth spreading method of the present embodiment. FIG. [Figure 2] 1 is a diagram showing an example of a fiber-spreading device according to a glass cloth fiber-spreading method of the present embodiment. FIG. [Figure 3] 1A to 1C are diagrams showing spray patterns obtained by various spray nozzles. DETAILED DESCRIPTION OF THE INVENTION

[0017] The glass cloth spreading method according to the present invention will be described in detail below with reference to the drawings, but the present invention is not limited thereto. In all the drawings, the same or corresponding parts are designated by the same reference numerals.

[0018] The glass cloth spreading method of the present invention includes a step of mixing a liquid and a gas such that the gas-water volume ratio V1 / V2 of the gas consumption rate V1 and the liquid spray rate V2 is in the range of 5 to 150, spraying the gas-liquid mixed mist into which the liquid has been atomized onto the glass cloth, and spreading the glass cloth. The spreading process is performed by a spreading treatment device. The spreading treatment device is not particularly limited. FIG. 1 is a cross-sectional schematic diagram showing an example of a spray nozzle used in the glass cloth spreading method of this embodiment. FIG. 2 is a diagram showing an example of a spreading treatment device S1 having this spray nozzle m. A gas-liquid mixed mist into which the liquid has been atomized is sprayed from the spray device having the spray nozzle m onto the surface of the silica glass cloth 200 on the support member 100. A two-fluid nozzle can be used as the spray nozzle m. The spray nozzle m has a gas-liquid mixing section L inside, and a gas supply section and a liquid supply section are connected to the spray nozzle m, respectively, and the gas consumption rate V1, the liquid spray rate V2, and the spray pressure can be changed by adjustment valves, respectively. G1 is a gas and W1 is an aqueous liquid, which are introduced into the gas-liquid mixing section L from their respective supply ports and mixed, and the gas flow is used to atomize the liquid to prepare a gas-liquid mixed mist. A plurality of spray nozzles m may be attached to the spray header M, and the silica glass cloth 200 may be transported on the support member 100.

[0019] [Gas-liquid mixed mist] The gas-liquid mixed mist of the present invention is a gas-liquid mixed mist obtained by mixing a gas with a liquid to atomize the liquid. The viscosity of the liquid to be mixed at 25°C is preferably 0.1 to 1,000 mPa·s, and more preferably 0.1 to 100 mPa·s. The viscosity is a value measured using a BM-type rotational viscometer. The rotor and rotation speed are appropriately selected depending on the viscosity so that the torque value falls between 10 and 100%. Within this range, the viscosity is low, so the liquid is easily atomized from the nozzle outlet, increasing the number of particles per unit time and the particle movement speed, and a better fiber-opening effect is expected.

[0020] The liquid to be mixed (aqueous liquid W1) may be water or a liquid obtained by blending water with one or more selected from alcohol, surfactant, silane coupling agent, lubricant, and colloidal silica. These may be appropriately selected depending on the type of glass, surface condition, thickness, etc. of the glass cloth. In addition, the sizing agent attached to the glass fiber bundle may be dissolved. The proportion of water in the liquid to be mixed is preferably 10 to 100 mass%, more preferably 50 to 100 mass%, and the upper limit may be 95 mass% or even 100 mass%.

[0021] A colloidal silica-containing aqueous liquid may be used as the liquid to be mixed (aqueous liquid W1). The colloidal silica-containing aqueous liquid is a colloidal solution of fine particles made of ultra-high molecular weight silicic anhydride. The volume-average particle diameter of these fine particles is preferably 5 to 500 μm, more preferably 70 to 100 μm. The volume-average particle diameter can be measured using a laser diffraction particle size distribution analyzer and can be determined as the mass average value D50 (i.e., the particle diameter or median diameter at which the cumulative mass is 50%) in particle size distribution measurement by laser light diffraction method.

[0022] The mass ratio of colloidal silica to the colloidal silica-containing aqueous liquid is preferably 0.01 to 5 mass%, more preferably 0.1 to 2 mass%, in which case the colloidal silica particles penetrate sufficiently between the glass filaments to secure gaps between the glass filaments, thereby obtaining a glass cloth with excellent resin impregnation.

[0023] The gas (G1) to be mixed may be air, nitrogen gas, or an inert gas, and may be used alone or in combination of two or more. Of these, compressed air is preferred.

[0024] The present invention includes a step of mixing a liquid and a gas at an air-water volume ratio V1 / V2 of the gas consumption rate V1 and the liquid spray rate V2 in the range of 5 to 150, spraying the gas-liquid mixed mist into which the liquid has been atomized onto a glass cloth, and spreading the glass cloth. V1 / V2 is preferably 8 to 50, more preferably 10 to 40. When the air-water volume ratio is in the range of 5 to 150, the beating force required for spreading the glass cloth can be sufficiently maintained. When the air-water volume ratio is outside this range, a sufficient spreading effect cannot be obtained, or filament breakage or fluffing occurs. Note that the air-water volume ratio V1 / V2 of the gas consumption rate V1 and the liquid spray rate V2 is measured immediately before (at the time of supply) the gas and liquid are respectively supplied to the gas-liquid mixing section L. The gas consumption rate V1 and the liquid spray rate V2 can be checked and adjusted as appropriate by, for example, attaching control valves, flow meters, or pressure gauges to the various pipes that supply the gas, liquid, etc. to the gas-liquid mixing section L, and the adjustment method is not particularly limited.

[0025] The gas-liquid mixed mist of the present invention is preferably a mixture in which the sum P1+P2 of gas pressure P1 and liquid pressure P2 is 0.2 to 2.0 MPa and the pressure ratio P1 / P2 is 0.2 to 1.5, with P1+P2 being preferably 0.5 to 1.0 and the pressure ratio P1 / P2 being preferably 0.6 to 1.2. Note that these pressures are those immediately before (at the time of supply) the gas and liquid are respectively supplied to the gas-liquid mixing section L, and these can be checked and adjusted as appropriate by providing various pressure regulating valves and pressure gauges in the various pipes that supply the gas, liquid, etc. to the gas-liquid mixing section L, and the adjustment method is not limited.

[0026] The temperature of the liquid to be mixed in the gas-liquid mixed mist is preferably 20 to 90°C, more preferably 40 to 70°C. By setting the liquid temperature within the above range, softening of the sizing agent attached to the glass fiber bundles is promoted, and the opening effect of the glass cloth in the opening treatment step can be improved. If the liquid temperature is less than 20°C, the softening of the sizing agent is likely to be insufficient, and even if the liquid temperature is higher than 90°C, the softening of the sizing agent is not promoted.

[0027] [Opening process and spraying process] The glass cloth conveying method is not particularly limited. For example, glass cloth wound in a roll can be unwound and then wound up, and it is preferable to apply a constant tension in the conveying direction (warp direction). In such a case, wrinkles and bends caused by the above-mentioned opening treatment process are suppressed. The tension in the warp direction can be adjusted as appropriate, but it is sufficient to use the normal tension required for conveyance. The opening treatment device S1 has a spray header M (spraying device) consisting of multiple spray nozzles m in the width direction that supplies and sprays the gas-liquid mixed mist, a support member 100, and rotors 11-14. As a result, while the silica glass cloth 200 wound in a roll is conveyed, the spraying device consisting of multiple spray nozzles m in the width direction sprays the gas-liquid mixed mist onto the surface of the silica glass cloth 200 conveyed on the support member 100, performing an opening treatment, and winding it into a roll by a roller 15. The tension in the warp direction for the silica glass cloth 200 can be adjusted as appropriate, but it is sufficient to use the normal tension required for conveyance.

[0028] The location where the droplets of the gas-liquid mixed mist are collided with the glass cloth may be either in the air or on a support member. For example, when the above treatment is performed on a support member, the energy generated by the collision is transmitted to the glass cloth, thereby further enhancing the opening effect. The support member is preferably one with few irregularities or a curved surface to facilitate smooth transport, since the glass cloth is pressed against the support member during transport due to the impact of the droplets of the gas-liquid mixed mist. Alternatively, the glass cloth may be opened by spraying the gas-liquid mixed mist on both sides.

[0029] The above-mentioned fiber-opening treatment step may be repeated two or more times, and is preferably repeated two or more times because the uniformity of the fiber-opening effect in the width direction of the glass cloth is further improved by performing the fiber-opening treatment step two or more times.

[0030] When carrying out the above-mentioned fiber-opening treatment step, the distance between the center of the spray nozzle of the gas-liquid mixed mist and the glass cloth and the spray irradiation angle of the spray direction (the spray irradiation angle (θ1 in FIG. 2 ) formed by the conveying direction V1 of the glass cloth and the spray direction V2 of the center of the nozzle of each attached spray nozzle m) are appropriately selected depending on the specifications of the above-mentioned gas-liquid mixed mist and the air-water volume ratio, and are not particularly limited. In order to maintain an appropriate impact force (hitting force) for the mist droplets to open the glass cloth, the distance between the spray nozzle and the glass cloth is preferably within a range of 1 to 200 mm.

[0031] Furthermore, when the spray pattern of the spray nozzle m is fan-shaped or conical, it is preferable that the spray angle (θ2 in FIG. 3) in the direction in which the spray pattern has the maximum diameter is 15° or more from the viewpoint of production costs. Furthermore, when the spray pattern of the spray nozzle m is fan-shaped or conical, each spray nozzle m needs to be fixed to the spray header. In this case, each spray nozzle can rotate around a fixed axis and can be freely adjusted in the cloth conveying direction. From the viewpoint of a uniform fiber-spreading effect, it is preferable that the spray patterns of adjacent spray nozzles do not directly overlap each other and that the direction in which the spray pattern has the maximum width is deviated by 1° or more from the width direction of the cloth.

[0032] [The gas-liquid mixed mist opens the glass cloth] Next, we will explain how the gas-liquid mixed mist sprayed from a two-fluid nozzle works to open glass cloth. In the strand-opening method using a water spray, the force (hereinafter referred to as "beating force") generated when droplets break into droplets impact the target glass cloth is used to apply scattered pressure to the surface of the warp and weft yarns (strands) composed of multiple glass filaments, thereby opening the strands. Spraying the gas-liquid mixed mist after adjusting its air-to-water volume ratio maximizes the effect of opening. In other words, with a two-fluid nozzle, the liquid and gas are mixed just before spraying, efficiently atomizing the liquid, narrowing the average particle size distribution, and creating a uniformly fine particle state. Furthermore, mixing with gas multiplies the velocity of the liquid particles in the direction of their travel, resulting in a higher particle velocity than with a single-fluid nozzle. This allows for a powerful spray without increasing the amount of water.

[0033] Furthermore, due to the above-mentioned effects, the beating force by the water spray is sufficiently increased, which allows the weft yarns to be sufficiently opened and the force binding the warp yarns to be made as small as possible. Furthermore, the atomized droplets can penetrate between the glass filaments, so that sufficient opening in the warp direction, which has been insufficient in the past, can be achieved.

[0034] The above-mentioned action contributes in a scattered manner to the entire surface of the glass cloth, and the strands are spread and at the same time the strand bundles are highly flattened, resulting in a glass cloth with extremely excellent surface smoothness.

[0035] The average particle size of the atomized gas-liquid mixed mist, i.e., the average spray particle size of the sprayed gas-liquid mixed mist, is preferably 10 to 500 μm, more preferably 10 to 300 μm, and even more preferably 10 to 200 μm. The average spray particle size of the gas-liquid mixed mist is measured using a laser Doppler method to calculate the Sauter Mean Dispersion (SMD) (hereinafter sometimes referred to as "droplet diameter"). The size of the mist droplets can be appropriately set by adjusting conditions such as the type of two-fluid nozzle, the spray pressure, and the distance between the two-fluid nozzle and the support member, and is not limited as long as the above-mentioned droplet diameter can be achieved. The type of two-fluid nozzle here refers to differences in spray flow rate, spray angle range, and spray distribution when the same spray pressure is applied to the nozzle.

[0036] The liquid pressure and air pressure during spraying are preferably adjusted within the range of 0.1 to 1.0 MPa so as to satisfy the above average spray particle diameter, and it is preferable to select a two-fluid nozzle used in the above treatment step that has a shape that can achieve this condition. If the above particle diameter is satisfied within this liquid pressure and air pressure range, fiber-spreading can be performed while sufficiently preventing fuzzing and misalignment.

[0037] In this case, it is preferable that the glass filaments are protected in advance by an organic substance, and by imparting flexibility to the strand, the filaments can be opened without becoming frayed by the high hitting force of the gas-liquid mixed mist, and therefore the filaments separate from each other simultaneously with the impact of the hitting force of the droplets, making opening easier, which is preferable.

[0038] Furthermore, in addition to the fiber-opening treatment using the gas-liquid mixture mist of the present invention, it is preferable to flatten the fibers constituting the glass cloth by using other fiber-opening treatments in combination. Examples of other fiber-opening treatments include fiber-opening using water flow pressure, fiber-opening using high-frequency vibrations with a liquid medium, processing using the pressure of a fluid with surface pressure, and processing using a pressing treatment with a roll. Among these fiber-opening treatment methods, processing using the pressure of a fluid with surface pressure and processing using a pressing treatment with a roll are more preferable because they can align the uniformity and fiber direction of the fibers and prevent misalignment. Furthermore, in order to enhance the effect of the flattening treatment, it is preferable to carry out the other fiber-opening treatments described above while reducing the tension applied to the glass cloth for transportation.

[0039] [Drying process after fiber opening process] For the purpose of drying after the opening treatment step, the glass cloth may be dried by air blowing with compressed air or by a heat drying step, for example, by passing the glass cloth through a hot air drying oven at 120°C for 10 minutes after the opening treatment step.

[0040] [Glass cloth (before opening)] Next, the glass cloth 200 to be subjected to the fiber-opening treatment will be described. The glass composition used for the glass cloth may be any known glass composition, such as E-glass, which is suitable for electrical insulation and is generally used for printed wiring boards, as well as D-glass, C-glass, S-glass, NE-glass, T-glass, and Q-glass, and may be selected appropriately depending on the application. Glass cloth suitable for stable substrates with low transmission loss and no variation preferably has an SiO2 content of 95.0 mass% or more, more preferably 98.0 to 100.0 mass%, and even more preferably 99.0 to 100.0 mass%.

[0041] The glass cloth is obtained by weaving glass fiber bundles composed of a plurality of glass filaments selected from the above glass compositions, and is formed, for example, by weaving warp and weft threads. Furthermore, in order to perform fiber-opening in the fiber-opening treatment step according to this embodiment, the thickness of the glass cloth is preferably 5 to 100 μm, more preferably 10 to 90 μm, and even more preferably 5 to 50 μm. In order to perform fiber-opening treatment efficiently, the thickness of the glass cloth is preferably 100 μm or less. Furthermore, if the thickness of the glass cloth is less than 5 μm, the woven fabric is likely to bend, which may reduce handleability. A thickness of 5 μm or more is preferable because it maintains rigidity and is less likely to bend or wrinkle. A thickness of 5 to 50 μm is more preferable because it allows for the production of glass cloth that meets the demand for thinner printed wiring boards. Although the width in the examples is 1,270 mm, this width is not particularly limited.

[0042] Examples of methods for producing glass filaments include electric melting and drawing using an oxyhydrogen flame, but the method is not limited to these as long as the glass filament diameter is 3 to 10 μm. For example, in the case of silica glass cloth using Q glass, a method is available in which a silica glass ingot raw material is drawn in an electric furnace to produce 150 to 350 μm silica glass threads, which are then spun using an oxyhydrogen burner. The thickness of the glass filaments obtained by various methods is preferably in the range of 3 to 10 μm. Glass filament strands are prepared by bundling multiple glass filaments with a sizing agent. This sizing agent is used to improve the convergence of the glass filaments and the protection and flight properties of the glass yarn during weaving, and is preferably a starch-based or PVA (polyvinyl alcohol)-based sizing agent as a film-forming agent component.

[0043] The glass yarn is prepared by twisting the above-mentioned glass filament strands using a twisting machine. The count of the glass yarn is preferably in the range of 0.5 to 20 tex. The count (tex) of the glass fiber bundle corresponds to the mass (grams) of the glass fiber per 1000 m. The weave of the glass cloth may be plain weave or twill weave, with plain weave being preferred.

[0044] The surface of the above glass cloth is covered with an organic substance, and the ignition loss measurement conditions are JIS R 3420:2013, the organic matter adhesion rate at 625°C for 2 hours is preferably 0.1% by mass or more, more preferably 0.3 to 5% by mass. Considering the glass cloth weaving process, examples of organic substances include the sizing agents mentioned above, or silane coupling agents used to improve affinity with resins after weaving the glass cloth. Among these, the opening treatment using the gas-liquid mixed mist mentioned above is more preferably a sizing agent. When the coated organic substance is a sizing agent, the opening treatment using the gas-liquid mixed mist softens the sizing agent by applying spray vibrations in an aqueous solution, making the fiber bundle more likely to open. On the other hand, after the deoiling process, in which the sizing agent is heat-treated in a heating furnace or the like to remove the sizing agent, the sizing agent solidifies due to heat, a phenomenon known as heat setting, which may result in insufficient opening. Therefore, it is preferable to perform the opening treatment before the deoiling process.

[0045] In the above embodiment, when the organic matter attached to the glass cloth is the sizing agent, the opening treatment step is carried out before the glass cloth raw roll is subjected to the deoiling treatment. On the other hand, a silane coupling agent is a suitable example of another organic matter in the glass cloth opening method of the present invention. That is, the glass cloth may be subjected to the deoiling treatment, and then further subjected to the silane treatment so that the organic matter attachment rate is 0.1 mass % or more, and then the opening treatment step may be carried out.

[0046] The silane coupling agent used in the silane treatment is a silane compound having a hydrolyzable group and a hydrophobic group (organic group). Examples of such compounds include silane coupling agents having an unsaturated double bond, such as vinyltriethoxysilane, vinyltrimethoxysilane, and γ-(methacryloyloxypropyl)trimethoxysilane; silane coupling agents having an epoxy group, such as β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidyloxypropyltrimethoxysilane, and γ-glycidyloxypropylmethyldiethoxysilane; silane coupling agents having a mercapto group, such as γ-mercaptopropyltrimethoxysilane; and silane coupling agents having an amino group, such as 3-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, and N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane.

[0047] [Open-fiber processed glass cloth] Next, the glass cloth subjected to the fiber-opening treatment using the gas-liquid mixed mist will be described. <Thickness> The thickness is preferably 5 to 100 μm, more preferably 5 to 70 μm. <Thickness ratio> When the thickness of the glass cloth before the fiber-opening treatment with the gas-liquid mixed mist is T1 and the thickness of the glass cloth after the fiber-opening treatment with the gas-liquid mixed mist is T2, the thickness ratio represented by T2 / T1 is preferably 0.6 to 0.9.

[0048] <Surface roughness ratio> Regarding the arithmetic mean roughness Ra according to JIS R 0601, when the arithmetic mean roughness of the glass cloth before the opening treatment with the gas-liquid mixed mist is Ra1 and the arithmetic mean roughness of the glass cloth after the opening treatment with the gas-liquid mixed mist is Ra2, the surface roughness ratio due to opening expressed as Ra2 / Ra1 is preferably 0.1 to 0.8, more preferably 0.1 to 0.6. The arithmetic mean roughness is not limited to a contact type or a non-contact type. This evaluation method makes it possible to evaluate the fine surface irregularities specific to glass cloth and is suitable for evaluating glass cloth with excellent surface smoothness.

[0049] <Warp occupancy rate> The warp occupation rate of the glass cloth that has been subjected to the above-mentioned fiber-opening treatment with the gas-liquid mixed mist is preferably 50 to 90%, more preferably 60 to 90%, and even more preferably 70 to 90%. <Weft Yarn Occupancy Rate> The weft occupation rate of the glass cloth subjected to the above-mentioned fiber opening treatment with the gas-liquid mixed mist is preferably 70 to 100%, more preferably 90 to 100%, and even more preferably 95 to 100%. <Porosity> The glass cloth that has been subjected to the fiber-opening treatment using the gas-liquid mixed mist preferably has a porosity of 0 to 10%, more preferably 0 to 6%, and even more preferably 0 to 4%. <Breathability> The air permeability of the glass cloth that was opened using the gas-liquid mixed mist was 70 cm 3 / cm 2 / s or less is preferable, and 50 cm 3 / cm 2 / s is more preferable, 30cm 3 / cm 2 / s is more preferable, 30cm 3 / cm 2 / s is particularly preferred.

[0050] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and various modifications can be made. For example, the conveying direction of the glass cloth may be vertical rather than horizontal to save space in the opening treatment process, or the glass cloth may be conveyed along a direction at a predetermined angle to the horizontal. However, considering the uniformity and quality of the opening of the glass cloth, it is preferable that the sprayed aqueous liquid does not pass through to the end of the glass cloth conveying direction (the winding side) but flows down. Furthermore, a mechanism for repeating opening by spraying and drying may be used as a process for connecting multiple opening treatment processes S1. Furthermore, the glass cloth conveying method is not limited. When the glass cloth is delivered by rollers, the diameter, number, position, etc. of the rollers can be appropriately changed depending on the thickness, mass, and other physical properties of the glass cloth.

[0051] According to this aspect, a method for spreading glass cloth having surface smoothness and sufficient spreading of both warp and weft yarns, which is necessary for the high-precision substrate processing that will become increasingly common in the future, can provide glass cloth having good smoothness and particularly excellent resin impregnation properties. [Example]

[0052] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0053] [Silica glass cloth manufacturing example] Preparation example 1: SQ11 A silica glass strand consisting of 200 silica glass filaments with a diameter of 5.3 μm and an SiO content of 99.9% by mass was prepared by applying a sizing agent to the silica yarn while stretching it at high temperature. Next, the obtained silica glass strand was twisted 0.4 times per 25 mm to prepare a silica glass yarn.

[0054] The obtained silica glass yarn was set in an air jet loom to weave a plain weave silica glass cloth (SQ11) with a warp density of 54 / 25 mm and a weft density of 54 / 25 mm. SQ11 had a tassel selvedge treatment, a thickness of 63 μm, and a cloth mass of 49.7 g / m. 2 The organic matter adhesion rate of SQ11 measured by ignition loss measurement was 2.3 mass%. The ignition loss measurement conditions were based on JIS R 3420:2013, and were 625°C for 2 hours.

[0055] Preparation example 2: SQ12 The SQ11 fabricated above, measuring 1,270 mm in width and 2,000 m in length, was placed in an electric furnace set at 400°C and heated for 72 hours to deoil. After heating, it was cooled to room temperature over 24 hours. It was then surface-treated with a silane coupling agent, KBM-903 (product name: Shin-Etsu Chemical Co., Ltd., 3-aminopropyltrimethoxysilane), and wound into a roll. This silica glass cloth was designated SQ12. The SQ12 had a thickness of 63 μm and a cloth mass of 48.7 g / m. 2 The organic matter adhesion rate measured by ignition loss was 0.2 mass %.

[0056] Preparation example 3: SQ21 A silica glass yarn was prepared in the same manner as in Preparation Example 1, except that the number of silica glass strands in Preparation Example 1 was changed from 200 to 100. A plain weave silica glass cloth (SQ21) with a warp density of 65 / 25 mm and a weft density of 68 / 25 mm was woven from the yarn. SQ21 had a tassel selvedge treatment, a thickness of 40 μm, and a cloth mass of 28.0 g / m. 2 The organic matter adhesion rate, as determined by ignition loss measurement in the same manner as in Preparation Example 1, was 2.3 mass %.

[0057] Preparation example 4: SQ31 A silica glass yarn was prepared in the same manner as in Preparation Example 1, except that the diameter of the silica glass filaments in Preparation Example 1 was changed from 5.3 μm to 4.0 μm and the number of filaments was changed from 200 to 50. Next, similar to Preparation Example 1, the yarn was set on an air jet loom and woven into a plain weave silica glass cloth raw fabric (SQ31) with a warp density of 75 / 25 mm and a weft density of 75 / 25 mm. SQ31 had a tassel selvedge treatment, a thickness of 28 μm, and a cloth mass of 17.9 g / m. 2 The organic matter adhesion rate, as determined by ignition loss measurement in the same manner as in Preparation Example 1, was 2.2 mass %.

[0058] [Example 1] The 1,270 mm-wide SQ11 was spread using a fiber spreader S1 (see Figure 2) equipped with a spray nozzle m (Figure 1). Specifically, the fiber spreader S1 used a PSN slit nozzle manufactured by Ikeuchi Co., Ltd. as a two-fluid nozzle. The nozzle was connected to a gas supply and a liquid supply, each with adjustable pressures. Tap water at 25°C was used as the aqueous liquid W1, and compressed air was used as the gas G1. The liquid pressure and gas pressure were adjusted to 0.3 MPa and 0.3 MPa, respectively, using the adjustment valves. The air-to-water volume ratio V2 / V1 was 35, and the average spray particle size was 70 μm. The gas-liquid mixed mist was sprayed from the slit nozzle at a distance of 500 mm from the glass cloth and at a 90° angle to the glass cloth plane. The support member 100 was a SUS304 plate with numerous 100 μm fine holes. The conveying speed of the silica glass cloth SQ11 by the roller was 5 m / min, the tension in the warp direction, which is the conveying direction of the silica glass cloth, was 20 N / m, and after the opening treatment step S1, a drying step was performed by air blowing, and then the cloth was taken up by the roller to obtain an opened silica glass cloth. The average spray particle size was measured by the laser Doppler method, and the Sauter mean particle diameter (SMD) (hereinafter sometimes referred to as "droplet diameter") was calculated.

[0059] [Example 2] An opened fiber treatment was carried out in the same manner as in Example 1, except that the silica glass cloth (SQ11) was changed to SQ12, to obtain an opened fiber silica glass cloth.

[0060] [Example 3] The opening treatment was carried out in the same manner as in Example 1 except that the temperature of the aqueous liquid W1 was set to 70°C, to obtain an opened silica glass cloth.

[0061] [Example 4] The fiber-opening treatment was carried out in the same manner as in Example 1, except that the liquid pressure was 0.7 MPa, the gas ejection pressure was 0.5 MPa, the air-water volume ratio was V2 / V1 = 40, and the average spray particle size was 120 μm, to obtain an opened silica glass cloth.

[0062] [Example 5] The fiber-opening treatment was carried out in the same manner as in Example 1, except that the liquid pressure was 0.6 MPa, the gas ejection pressure was 0.3 MPa, the air-water volume ratio was V2 / V1 = 8, and the average spray particle size was 250 μm, to obtain an opened silica glass cloth.

[0063] [Example 6] A fiber-opening process was carried out in the same manner as in Example 1, except that a nozzle with a different specification from that in Example 1 was used, where the liquid pressure was 0.3 MPa, the gas ejection pressure was 0.3 MPa, the air-water volume ratio was V2 / V1 = 100, and the average spray particle size was 40 μm, to obtain a spread silica glass cloth.

[0064] [Example 7] A fiber-opening process was carried out in the same manner as in Example 1, except that a nozzle with a different specification from that in Example 1 was used, where the liquid pressure was 0.2 MPa, the gas ejection pressure was 0.5 MPa, the air-water volume ratio V2 / V1 was 150, and the average spray particle size was 40 μm, to obtain a spread silica glass cloth.

[0065] [Example 8] A spread silica glass cloth was obtained by carrying out the same fiber-opening treatment as in Example 1, except that a colloidal silica-containing aqueous liquid with a viscosity of 6.2 mPa s was used as the aqueous liquid W1 instead of tap water. The colloidal silica used had an average atomized particle size of 70 μm, and the concentration of the colloidal silica-containing aqueous liquid was 0.2 mass%.

[0066] [Example 9] An opened fiber treatment was carried out in the same manner as in Example 1, except that SQ21 was used instead of SQ11 in Example 1, to obtain an opened fiber silica glass cloth.

[0067] [Example 10] An opened fiber treatment was carried out in the same manner as in Example 1, except that SQ11 in Example 1 was changed to SQ31, to obtain an opened fiber silica glass cloth.

[0068] [Comparative Example 1] The opening treatment was carried out in the same manner as in Example 1 except that the liquid pressure was 0.2 MPa, the atmospheric pressure was 0.6 MPa, the pressure ratio was 3.0, and the air-water volume ratio V2 / V1 was 170, to obtain an opened silica glass cloth.

[0069] Comparative Example 2 The opening treatment was carried out in the same manner as in Example 1 except that the liquid pressure was 0.6 MPa, the atmospheric pressure was 0.1 MPa, the pressure ratio was 0.2, and the air-water volume ratio was V2 / V1=3, to obtain an opened silica glass cloth.

[0070] Comparative Example 3 In Example 1, a VVP6020 (manufactured by Ikeuchi Co., Ltd.) was used as the one-fluid nozzle, the liquid pressure was 0.5 MPa, and no gas was used. The same procedure as in Example 1 was repeated to obtain an opened silica glass cloth.

[0071] Comparative Example 4 The opening treatment was carried out in the same manner as in Example 1, except that an opening treatment step using an ultrasonic treatment tank was provided instead of the opening treatment step S1, and an opened silica glass cloth was obtained. Specifically, an ultrasonic generator vibrator was placed inside a single-tank treatment tank, and an aqueous liquid W2 was stored inside the treatment tank. The silica glass cloth was transported inside the treatment tank using rollers, so that the silica glass cloth was immersed in the aqueous liquid W2, and ultrasonic treatment was performed on the silica glass cloth, thereby obtaining an opened silica glass cloth. The size of one side of the vibrator was 200 mm, the output frequency was 100 kHz, and the ultrasonic power density was 1.2 kW.

[0072] Comparative Example 5 Except for using a high-pressure water jet instead of the opening device S1, the opening treatment was carried out in the same manner as in Example 1 to obtain an opened silica glass cloth. The high-pressure water jet treatment step can be performed using conventionally known techniques, and in this comparative example, a method was used in which a plurality of nozzles with a diameter of 0.1 to 0.2 mm were arranged in the width direction of the running woven fabric, and the nozzles were moved at high speed to spray very thin columnar streams.

[0073] The evaluation method for the spread silica glass cloth is shown below. (1) Warp occupancy rate (%), weft occupancy rate (%), void ratio (%), air permeability (cm 3 / cm 2 / sec) A sample of 1270 mm wide x 50 mm long was taken from the silica glass cloth, and 20 samples were taken at equal intervals in the width direction, and 3 rows were taken in the length direction, for a total of 60 samples. The thickness (μm), warp occupancy rate (%), weft occupancy rate (%), and air permeability (cm 3 / cm 2 / sec) was measured. Measurements were made at 60 locations in each of the examples and comparative examples, and the average value was calculated for each value. The standard deviation of the air permeability was also calculated. The warp occupancy rate, weft occupancy rate, and void ratio were calculated as follows based on the numerical values ​​of the glass fibers constituting the glass cloth. Warp occupancy rate = A1 / A x 100 (%) Weft occupancy rate = B1 / B x 100 (%) Porosity={(A-A1)×(B-B1) / A×B}×100(%) A: Warp spacing, A1: Warp width, B: Weft spacing, B1: Weft width (2) The thickness ratio was calculated based on the following formula. Thickness ratio = T2 / T1 T1: Glass cloth thickness before fiber spreading, T2: Glass cloth thickness after fiber spreading (3) The surface roughness ratio was calculated based on the following formula. The arithmetic mean roughness Ra was calculated by observing the surface with a color 3D laser microscope VK-9710 (manufactured by Keyence Corporation, magnification 400 times). Surface roughness ratio = Ra2 / Ra1 Ra1: arithmetic average of glass cloth before fiber spreading, Ra2: surface roughness of glass cloth after fiber spreading (4) Visual inspection of glass cloth After the glass cloth was opened, the appearance of the glass cloth was observed under a microscope to check for any defects that could become defects. · No defects in appearance: ○ - Defects in appearance: ×

[0074] The table below shows the fiber-spreading conditions and the evaluation results after fiber-spreading for the examples and comparative examples. [Table 1]

[0075] [Table 2]

[0076] [Table 3]

[0077] In Examples 1 to 9, the thickness ratio of the glass cloth before and after spreading was less than about 0.9, and the air permeability value was about 30 cm in Examples 1 to 9 using SQ11, SQ12, and SQ21. 3 / cm2 / s or less, approximately 50 cm in Example 10 using SQ31 3 / cm 2 / s or less, which is sufficiently low, and the weft occupancy rate is also high at approximately 85% or more. The warp occupancy rate is also approximately 70% or more, and the void ratio is approximately 3% or less, which shows that the warp yarns are also sufficiently opened. In addition, the variation in air permeability between each sample is approximately 10cm 3 / cm 2 / s or less, and the arithmetic mean roughness ratio before and after spreading was also 0.8 or less, both of which were low values, indicating that the glass cloth of the present invention has a uniform spreading effect in the width direction and is extremely excellent in surface smoothness. From the above, it can be seen that the glass cloth of the present invention has extremely excellent surface smoothness and uniform resin impregnation. Furthermore, when the appearance of the glass cloth was observed under a microscope, no misalignment or fluffing was found in the examples.

[0078] On the other hand, the opened silica glass cloth (comparative example) outside the scope of the present invention had a worse opening effect than the examples, as evaluated from the values ​​of air permeability and warp and weft void ratio. The variations in air permeability in the width direction and the arithmetic mean roughness ratio before and after opening were also large, and a uniform opening effect and sufficient surface smoothness were not obtained. Furthermore, it was not possible to ensure glass cloth quality without defects such as misalignment and fluff, which would cause substrate defects. As shown in Table 1, the results of Examples 1 and 2 confirmed that a greater opening effect was achieved when this opening treatment process was performed on raw silica glass cloth with sizing agent attached before the deoiling process.

[0079] According to the present invention, as a method for realizing precision processing of substrates for high-speed communications such as 5G, which will become increasingly common in the future, a glass cloth is treated with a simple method of treating the glass cloth with a gas-liquid mixed mist having an adjusted gas-water volume ratio. This method makes it possible to provide a glass cloth that has extremely excellent surface smoothness, in which both warp and weft threads are sufficiently spread, and which is particularly excellent in uniform resin impregnation, and which can suppress the occurrence of pinholes in prepregs using the glass cloth, as well as methods for spreading and manufacturing the glass cloth.

[0080] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and anything that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits similar effects is included within the technical scope of the present invention. [Explanation of symbols]

[0081] W1 Water-based liquid G1 Gas m Spray nozzle L Gas-liquid mixing section 11~15 Laura S1 Fiber opening processing equipment M spray header m Spray nozzle 100 support member 200 Glass Cloth

Claims

1. SiO 2 The method for spreading glass cloth having a content of 95.0% by mass or more includes the steps of mixing a liquid and a gas such that the gas-water volume ratio V1 / V2 of the gas consumption amount V1 and the liquid spray amount V2 is in the range of 5 to 150, atomizing the liquid, spraying the gas-liquid mixed mist having an average particle diameter of 5 to 500 μm onto the glass cloth, and spreading the glass cloth.

2. 2. The method for spreading glass cloth according to claim 1, wherein the gas-liquid mixed mist is a mixture in which the sum (P1+P2) of the gas pressure P1 and the liquid pressure P2 is 0.2 to 2.0 MPa and the pressure ratio (P1 / P2) is 0.2 to 1.

5.

3. 3. The method for spreading glass cloth according to claim 1, wherein the temperature of the liquid to be mixed is 20 to 90°C.

4. The method for spreading glass cloth according to any one of claims 1 to 3, wherein the liquid to be mixed is water or a liquid obtained by blending water with one or more selected from alcohol, surfactants, silane coupling agents, lubricants, and colloidal silica.

5. 5. The method for spreading glass cloth according to claim 1, wherein the gas to be mixed is at least one gas selected from the group consisting of air, nitrogen gas and inert gas.

6. 6. The method for spreading glass cloth according to claim 1, wherein the glass cloth has a thickness of 5 to 100 μm.

7. The method for spreading glass cloth according to any one of claims 1 to 6, which is a method for spreading silica glass cloth whose surface is coated with an organic substance and whose organic substance adhesion rate is 0.1 mass% or more when measured at 625°C for 2 hours under ignition loss measurement conditions based on JIS R3420:2013.

8. The method for spreading glass cloth according to any one of claims 1 to 7, which is a method for spreading silica glass cloth having a sizing agent attached thereto before a deoiling step.

9. 9. The method for spreading a glass cloth according to claim 1, wherein the thickness of the glass cloth before the spreading treatment is 5 to 100 μm.

10. The method for spreading a glass cloth according to any one of claims 1 to 9, wherein the warp occupancy of the glass cloth after spreading treatment is 50 to 90% and the weft occupancy of the glass cloth is 70 to 100%.

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