JP2024117982A - Glass yarn, glass cloth and production method of glass yarn - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass yarn with occurrence of fuzz suppressed.

SOLUTION: A glass yarn includes a plurality of glass filaments converged, having an average filament diameter of 4.7 μm or less, and a split yarn ratio of 7% or less. A production method of glass yarn includes a step of converging glass filaments with a convergence member having a slit structure. The slit has a width that satisfies a following formula. (D×N)×0.3≤Width of slit (μm)≤(D×N)×1.5, D: average filament diameter of warp or weft (μm), N: number of filaments of warp or weft (pieces).

SELECTED DRAWING: Figure 5

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to glass yarn, glass cloth, and a method for manufacturing glass yarn.

Glass yarn is made by twisting together multiple glass filaments into a thread. Glass yarn has excellent properties such as electrical insulation, dimensional stability, heat resistance, chemical resistance, and tensile strength, and is therefore used as the raw material thread for glass cloth, glass tape, glass sleeves, rubber reinforcing cords, etc. One of the uses of glass cloth is printed wiring boards, which have a significant impact on the quality of printed wiring boards. Glass cloth for printed wiring boards is becoming thinner, and as a result, the glass yarn, which is the raw material thread, is also becoming lower in count.

A glass yarn package in which the glass yarn is wound is manufactured through a spinning process and a twisting process as described below.
(1-1) Spinning process: A glass raw material is melted in a glass melting furnace and drawn out from a nozzle as a plurality of glass filaments, and a bundling agent is applied to the plurality of glass filaments to bundle them into a glass strand. A collet equipped with a cylindrical winding tube is then rotated to wind up the glass strand onto the tube, forming a cake (a cylindrically wound mass of thread formed by winding up the strand immediately after it is fiberized from the bushing in the spinning process).
(1-2) Yarn twisting process
Glass strands are pulled out from the cake, twisted in a twisting machine to form glass yarn, and wound around cylindrical bobbins to form glass yarn packages.

A long glass fiber bundling agent containing starch as a non-volatile component is known, characterized in that the starch contains 25% by mass or more and 100% by mass or less of its total amount of amylose and has an average particle size in the range of 1 to 12 μm (see, for example, Patent Document 1). According to this long glass fiber bundling agent, the starch contains 25% by mass or more and 100% by mass or less of its total amount of amylose, so that the viscosity is low and the starch can penetrate uniformly into the gaps between the long glass fiber filaments, and it is said that the starch can bond multiple long glass fiber filaments together to obtain excellent bundling properties.

JP 2013-112917 A

The inventors have found that the glass yarn to which the long glass fiber bundling agent of Patent Document 1 has been added still has room for improvement in terms of its fuzz suppression effect. Therefore, the main objective of the present invention is to provide a glass yarn that solves the above problems and suppresses the generation of fuzz.

The inventors have conducted research to solve the above problems, and have found that when the long glass fiber sizing agent of Patent Document 1 is applied to a glass yarn having an average filament diameter of 4.7 μm, for example, and the glass yarn is observed, localized yarn breakage occurs in the longitudinal direction of the glass yarn. Figure 1 is an example of an image of a glass yarn taken and measured with an inline projection image measuring instrument (TM-X5006 series sensor head (φ6 mm type)) manufactured by Keyence Corporation, which explains yarn breakage. As illustrated in Figure 1, specifically, the inventors have found that due to insufficient bundling of the glass yarn, some of the glass filaments constituting the glass yarn are not twisted together with other glass filaments in the longitudinal direction of the glass yarn, and the glass yarn is partially split into multiple strands in the longitudinal direction. After further investigation, the inventors discovered that the glass yarn's yarn breakage rate, which will be described later, is an effective indicator of yarn breakage, that fuzz can be suppressed by keeping the yarn breakage rate within a specific range, and that glass yarn with a yarn breakage rate within that specific range can only be obtained by focusing the yarn using a focusing member with a slit structure having a specific width.

Figure 2 is a schematic diagram of a conventional focusing member for a spinning process, with Figure 2(A) being a view from the front, back, top, and bottom, and Figure 2(B) being a view from the right and left sides. Also, Figure 3 is a schematic front view showing an example of a glass strand manufacturing apparatus that produces glass strands in a spinning process. In Figure 2, the conventional focusing member 1 is composed of a cylindrical portion 1a and two truncated cone portions 1b that extend from the cylindrical portion 1a in the left-right direction of the page (towards the side) so that their outer diameters gradually increase from the outer diameter of the cylindrical portion. The cylindrical portion 1a has a length of 1L.

3, the spinning device 200 includes a sizing agent tray 201 that applies a sizing agent to the glass filaments discharged from the nozzle 40, a bundling mechanism 202 that bundles the glass filaments 3 into a predetermined number of glass strands, a traverse mechanism 206 that traverses the glass strands, and a winding roller 211 that winds up the glass strands. The sizing agent tray 201 includes a sizing agent that is supplied to the sizing agent tray 201, and an applicator (not shown) that picks up the sizing agent and applies the sizing agent to the glass filaments 3 by contacting the picked-up sizing agent. Instead of the bundling tray 201, the sizing agent can be applied to the glass filaments by spray injection, etc. The bundling mechanism 202 includes a horizontal bundling shaft 203 that is rotated by a motor, etc., and a plurality of bundling members 1 fixed to the bundling shaft 203. Thus, the glass filaments 3 discharged from the through-hole of the nozzle 40 are divided into two fiber bundles 4 (glass strands) by each of the two bundling members 1 as the bundling shaft 203 rotates. Before being divided into two fiber bundles 4 by the bundling member 1, each glass filament 3 is introduced into a bundling agent tray 201 containing a bundling agent, and the bundling agent is applied to the glass filaments 3. The traverse mechanism 206 has a horizontal traverse shaft 207 that is driven to rotate by a motor or the like, and traverse members 209 corresponding to each of the two bundling members 1. Each fiber bundle 4 focused by the two focusing members 1 is traversed by the traverse member 209 by the rotational drive of the traverse shaft 207, and is evenly wound up by the winding roller 211. The winding roller 211 rotates about a predetermined rotation axis, and the rotation speed, rotational drive force, and the like are adjusted. This adjusts the spinning tension (pulling tension) and spinning speed of the molten glass discharged from the nozzle 40, and winds up the fiber bundle. The resulting glass strand is then twisted using a ring twisting machine or the like to produce a glass yarn. The glass yarn is then wound around a bobbin to produce a glass yarn package.

The inventor here found that when a glass filament bundle is manufactured using the conventional bundling member shown in Figure 2, the width of the glass filament bundle becomes relatively large, and the tension applied to the glass filament bundle fluctuates due to the traverse, making the width of the glass filament bundle prone to become non-uniform. The inventor then found that there is room for improvement in the uniformity of the width of the glass filament bundle.

The inventors conducted extensive research and discovered that glass yarn with a specific range of yarn breakage rate can only be obtained by converging the yarn using a converging member with a slit structure having a specific width, as shown in Figure 4, and that the generation of fuzz can be suppressed by using this glass yarn.

That is, the present invention provides the following aspects.
Item 1. A glass yarn formed by bundling a plurality of glass filaments, the glass yarn having an average filament diameter of 4.7 μm or less and a yarn breakage rate of 7% or less.
Item 2. The glass yarn according to item 1, wherein the number of the glass filaments is 70 or less.
Item 3. The glass yarn according to item 1, wherein the number of twists of the glass yarn is 0.3 to 1.2 times/25 mm.
Item 4. A glass cloth woven using the glass yarn according to any one of items 1 to 3 as a warp and/or a weft.
Item 5. A method for producing a glass yarn according to any one of Items 1 to 3, comprising a step of bundling glass filaments with a bundling member having a slit structure, the width of the slit satisfying the following formula:
(D×N)×0.3≦slit width (μm)≦(D×N)×1.5
D: average filament diameter of warp or weft (μm)
N: Number of warp or weft filaments (pieces)
Item 6. A method for detecting breakage in a glass yarn, comprising the steps of running one glass yarn to be measured and continuously photographing the glass yarn in the longitudinal direction, detecting the number of glass yarns from the photographed images, and judging a portion where the glass yarn is not twisted together and is partially divided into two or more strands as a breakage.

The glass yarn of the present invention is a glass yarn formed by bundling multiple glass filaments, has an average filament diameter of 4.7 μm or less, and has a yarn breakage rate of 7% or less, which makes it possible to suppress the generation of fluff.

FIG. 1 is an example of an image of a glass yarn photographed and measured with an in-line projection image measuring instrument (TM-X5006 series sensor head (φ6 mm type)) manufactured by Keyence Corporation, which will explain yarn breakage. 2A and 2B are schematic diagrams of a conventional spinning process focusing member, in which FIG. 2A shows the front, back, top and bottom views, and FIG. 2B shows the right and left side views. FIG. 1 is a schematic side view showing an example of a glass filament bundle manufacturing apparatus that manufactures glass strands (glass filament bundles) to be used as glass yarns in a spinning process. 4A is a schematic diagram showing an example of a focusing member having a slit structure with a specific width, where FIG. 4A is a schematic plan view, FIG. 4B is a schematic bottom view, FIG. 4C is a schematic front view (i.e., in FIG. 4A, the upper side of the paper is the front side and the lower side of the paper is the rear side), FIG. 4D is a schematic rear view, FIG. 4E is a schematic right side view, and FIG. 4F is a schematic left side view. FIG. 4(A) is a partially enlarged view illustrating how glass filaments are bundled by a bundling member having a slit structure. FIG. 1 is a schematic front view showing an example of a glass filament bundle manufacturing apparatus that produces glass strands (bundles of glass filaments) to be used as glass yarns in a spinning process. FIG. 1 is a schematic front view showing an example of a glass filament bundle manufacturing apparatus that produces glass strands (bundles of glass filaments) to be used as glass yarns in a spinning process.

The glass yarn of the present invention is a glass yarn formed by bundling a plurality of glass filaments, has an average filament diameter of 4.7 μm or less, and has a yarn breakage rate of 7% or less. The details are described below.

In the glass yarn of the present invention, the glass material constituting the glass filaments and the glass yarn is not particularly limited. Examples include E glass, T glass, S glass, UT glass, D glass, NE glass, L glass, LU glass, C glass, or AR glass manufactured by Unitika Ltd.

From the viewpoint of versatility, it is preferable to use glass filaments having an E-glass composition, which is a composition containing, relative to the total amount of the glass filaments, SiO ₂ in the range of 52 to 56 mass%, B ₂ O ₃ in the range of 5 to 10 mass%, Al ₂ O ₃ in the range of 12 to 16 mass%, CaO and MgO in the range of 20 to 25 mass% in total, and Li ₂ O, K ₂ O, and Na ₂ O in the range of 0 to 1 mass% in total.

From the viewpoint of further increasing the strength of the prepreg and the printed wiring board, the glass filaments are preferably made of a glass material containing SiO ₂ in the range of 60 to 66 mass %, Al ₂ O ₃ in the range of 20 to 26 mass %, and MgO in the range of 10 to 15 mass % relative to the total amount of the glass filaments.

From the viewpoint of reducing the dielectric constant and dielectric tangent of the prepreg and the printed wiring board, the glass filaments are preferably made of a glass material containing SiO ₂ in the range of 45 to 60 mass %, B ₂ O ₃ in the range of 15 to 35 mass %, and Al ₂ O ₃ in the range of 10 to 20 mass % relative to the total amount of the glass filaments, and more preferably made of a glass material containing SiO ₂ in the range of 45 to 55 mass %, B ₂ O ₃ in the range of 20 to 35 mass %, and Al ₂ O ₃ in the range of 10 to 20 mass % relative to the total amount of the glass filaments.

The average filament diameter of the glass filaments constituting the glass yarn of the present invention is 4.7 μm or less, and from the viewpoint of more effectively exerting the effect of suppressing the generation of fluff, it is preferably 3 to 4.7 μm, and more preferably 3 to 4.2 μm. The number of glass filaments constituting the glass yarn of the present invention is not particularly limited, but for example, 20 to 70 can be mentioned, and 20 to 55 is more preferably mentioned. The average yarn count can be one or more ranges selected from the group consisting of 3.3 to 3.8 tex and 3.8 to 4.2 tex. The average number of filaments can be one or more ranges selected from the group consisting of 34 to 38, 39 to 44, and 45 to 55. In the present invention, the average filament diameter of the glass filaments is measured and calculated according to the method specified in the B method (cross-sectional method) of "7.6 Single fiber diameter" of "General test method for glass fibers" of the Japanese Industrial Standard JIS R 3420: 2013. Specifically, the glass yarn is embedded in an epoxy-based cold embedding resin (manufactured by Struers, product name: Epoxy Resin Specifix-40) and cured to obtain a cured product. Next, the cured product is polished to an extent that the glass yarn embedded in the epoxy-based cold embedding resin can be observed, and the average diameter is observed and measured at a magnification of 2000 times and the number of fibers is observed and measured using a scanning electron microscope (SEM) (manufactured by JEOL, product name: JSM-6390A) at a magnification of 500 times. Thirty glass yarns are randomly selected, and the diameters (largest part) of all the glass filaments in the 30 glass yarns are measured in the cross section, and the arithmetic mean value is calculated to be the average diameter of the glass filaments in the glass yarn. The number of glass filaments constituting the glass yarn is measured when measuring the average diameter of the glass filaments.

The count of the glass yarn of the present invention is not particularly limited, but may be, for example, 0.5 to 5 tex, preferably 0.5 to 3 tex, and more preferably 0.8 to 2 tex. The count of the glass yarn may be, for example, one or more ranges selected from the group consisting of 0.8 to 1.1 tex, 1.2 to 1.4 tex, and 1.5 to 2 tex. In the present invention, the count of the glass yarn is measured and calculated according to the method specified in "7.1 Count" of the Japanese Industrial Standard JIS R 3420: 2013 (General Test Method for Glass Fibers). Specifically, first, 500 m of glass yarn is taken from a bobbin on which the glass yarn is wound, and this is used as a test piece. The test piece is placed flat and placed in an oven, dried at 105 ° C. for 60 minutes, and then cooled in a desiccator, and the mass of the test piece is measured. The count is calculated according to the following formula.
t=(m/500)×1000
t: number m: mass of test piece (g)

The glass yarn of the present invention may contain a film-forming component on the surface of the glass filament. Examples of the film-forming component include starch and synthetic resin. There are no particular limitations on the starch, and examples of the starch include corn starch, tapioca starch, wheat starch, sweet potato starch, potato starch, high amylose corn starch, sago starch, rice starch, and soybean starch. Examples of the synthetic resin include epoxy resin, urethane resin, and acrylic resin.

The glass yarn of the present invention may also contain other components on the surface of the glass filaments in addition to the film-forming components. Examples of such other components include lubricants, softeners, antistatic agents, emulsifiers, etc. Specific examples include animal and vegetable oils, waxes or their emulsified forms, cationic surfactants, anionic surfactants, nonionic surfactants, etc.

The ignition loss of the glass yarn of the present invention is not particularly limited, but may be, for example, 0.7 to 1.5% by mass. In the present invention, the ignition loss of the glass yarn is a value measured according to the method specified in "7.3.2 Ignition loss" of "General test method for glass fibers" of Japanese Industrial Standard JIS R 3420 2013.

The glass yarn of the present invention has a yarn breakage rate of 7% or less. As described above, as illustrated in FIG. 1, specifically, it was found that due to insufficient convergence of the glass yarn, some of the glass filaments constituting the glass yarn are not partially twisted together with other glass filaments in the longitudinal direction of the glass yarn, and the glass yarn is partially divided into several parts in the longitudinal direction. After further investigation, the inventors found that the yarn breakage rate of the glass yarn is effective as an indicator of the above-mentioned yarn breakage, that fuzz can be suppressed by setting the yarn breakage rate within a specific range, and that a glass yarn with a yarn breakage rate within the specific range can only be obtained by converging using a converging member with a slit structure having a specific width.

In the present invention, the yarn breakage rate of the glass yarn is measured as follows. That is, an in-line projection image measuring instrument (TM-X5006 series sensor head (φ6 mm type)) manufactured by Keyence Corporation is used as a measuring instrument, and one glass yarn is pulled out from the glass yarn package and continuously passed through the projected and received light. The running conditions when the glass yarn is passed through the projected and received light are a speed of 23 m/min and a tension of 0.001 (N) or less, and a portion where the glass yarn is partially divided into multiple strands in the longitudinal direction (a portion where the number of strands is two or more under the measurement conditions described below) is regarded as a yarn breakage. The yarn breakage rate (%) is calculated by the number of broken strands/total number of measurements x 100. The measurement is performed using analysis software (for example, TM-X Navigator manufactured by Keyence Corporation) attached to the above measuring instrument, and the software is set to the number of measuring tools. The detailed conditions when the number of measuring tools is set can be as follows.
Tool name: Number tolerance setting Design value: 0001 Moving average: 1 Treatment setting Alarm hold count: 000 Scaling: Not set Offset: 0000 Zero reference value: 0000 Peak detection filter: None Hold mode: None Edge detailed setting Segment size: 0001
Interval: 0001
Sensitivity: 30%
Filter width: 010
・Strength lower limit: 010
・Outside area processing (high speed): Unchecked area specified ・Start point: X = 003.000 mm Y = 002.000 mm
End point: X = 003.000 mm Y = 005.167 mm
Detection width: 0.300 mm
Length: 3.167mm
・Position correction source: No. 1
Area adjustment during setting Reference: Arbitrary straight line Orientation: Parallel to reference Mask setting Mask area 1: None Mask area 2: None Mask area 3: None Mask area 4: None

To achieve the above yarn breakage rate, the manufacturing method of the glass yarn of the present invention described below is suitable.

In the present invention, the width of the glass yarn is not particularly limited, and may be, for example, 30 to 100 μm. In the present invention, the width of the glass yarn is measured as follows. That is, an in-line projection image measuring instrument (TM-X5006 series sensor head (φ6 mm type)) manufactured by Keyence Corporation is used as a measuring instrument, and the glass yarn is pulled out from the glass yarn package and continuously passed through the projected and received light. The running conditions when the glass yarn is passed through the projected and received light are a speed of 23 m/min and a tension of 0.001 (N) or less. The measurement is performed using analysis software (for example, TM-X Navigator manufactured by Keyence Corporation) attached to the above measuring instrument, and the measurement tool is set to the average outer diameter as the setting of the software. The detailed conditions when the measurement tool is set to the average outer diameter can be as follows.
Tool name: Average outer diameter measurement Contents: Average tolerance design Moving average: 1 time treatment setting Alarm hold count: 000 times Scaling: Unchecked Offset: 0000 Zero reference value: 0000 Peak detection filter: None Hold mode: None Decimal points: 3 digits Display unit: mm
Enable DIA correction: Checked Remove outliers: No Edge detail settings Segment size: 0001
Interval: 0001
Sensitivity: 10%
・Filter width: 005
・Strength minimum: 025
・Outside area processing (high speed): Unchecked area specified ・Start point: X = 003.000 mm Y = 002.000 mm
End point: X = 003.000 mm Y = 005.167 mm
Detection width: 0.300 mm
Length: 3.167mm
・Position correction source: No. 1
Area adjustment during setting Reference: Arbitrary straight line Orientation: Parallel to reference Mask setting Mask area 1: None Mask area 2: None Mask area 3: None Mask area 4: None

The lower limit of the yarn breakage rate of the glass yarn of the present invention is not particularly limited, but may be, for example, 0.5% or more or 1.0% or more. The lower limit may also be 3% or more, or 5% or more. In the glass yarn of the present invention, the particularly suitable yarn breakage rate when the yarn count is 0.8 to 1.1 tex is preferably 5% or less, more preferably 2% or less. In the glass yarn of the present invention, the particularly suitable yarn breakage rate when the yarn count is 1.2 to 1.4 tex is preferably 5% or less. In the glass yarn of the present invention, the particularly suitable yarn breakage rate when the yarn count is 1.5 to 2 tex is 7% or less. In the glass yarn of the present invention, the particularly suitable yarn width when the yarn count is 0.8 to 1.1 tex is preferably 40 to 60 μm, more preferably 45 to 55 μm. In addition, in the glass yarn of the present invention, when the yarn count is 1.2 to 1.4 tex, the yarn width that is particularly suitable is preferably 50 to 70 μm, and more preferably 55 to 65 μm. In addition, in the glass yarn of the present invention, when the yarn count is 1.5 to 2 tex, the yarn width that is particularly suitable is preferably 60 to 80 μm, and more preferably 65 to 75 μm.

The glass yarn of the present invention can have a twist number of 0.3 to 1.2 times/25 mm. In the present invention, the twist number is measured in accordance with JIS R 3420:2013 7.5.

Next, a method for producing the glass yarn of the present invention will be described. The method for producing the glass yarn of the present invention includes a step of bundling glass filaments with a bundling member having a slit structure, and the width of the slit satisfies the following formula:
(D×N)×0.3≦slit width (μm)≦(D×N)×1.5
D: average filament diameter of warp or weft (μm)
N: Number of filaments in the warp or weft

2 is a schematic diagram of a focusing member in a conventional spinning process, and FIG. 4 is a schematic diagram illustrating an example of a focusing member with a slit structure used in producing raw glass yarns used as weft yarns in weaving the glass cloth of the present invention, in which FIG. 4(A) is a schematic plan view, FIG. 4(B) is a schematic bottom view, FIG. 4(C) is a schematic front view (i.e., in FIG. 4(A), the upper side of the paper is the front side and the lower side of the paper is the rear side), FIG. 4(D) is a schematic rear view, FIG. 4(E) is a schematic right side view, and FIG. 4(F) is a schematic left side view. FIG. 5 is a partially enlarged view of FIG. 4(A), illustrating how glass filaments 6 are focused by a focusing member 2 with a slit structure. FIG. 6 is a schematic front view showing an example of a glass filament bundle manufacturing device that produces glass strands 4 (bundles of glass filaments 3) to be used as glass yarns in a spinning process. In FIG. 6, the focusing member 1 in FIG. 3 described above is replaced with the focusing member 2 shown in FIG. 4 and FIG. 5, and the focusing member 2 in FIG. 6 is provided in a direction that coincides with the front direction shown in FIG. 4(C).

As mentioned above, the inventors discovered that when a glass filament bundle is manufactured using the conventional bundling member shown in FIG. 2, the width of the glass filament bundle becomes relatively large, and the tension applied to the glass filament bundle fluctuates due to the traverse, making the width of the glass filament bundle prone to become non-uniform and increasing the rate of yarn breakage.

The inventors have conducted extensive research and have found that the glass yarn of the present invention can be produced by spinning glass filament bundles using a converging member 2 with a slit structure as shown in Figures 4 and 5.

With reference to Figures 4 and 5, we will explain one embodiment of a bundling member with a slit structure that can produce the glass yarn of the present invention.

The focusing member 2 of the slit structure of Figures 4 and 5 has a slit. In the embodiment shown in Figures 4 and 5, the slit is U-shaped when viewed from the planar direction, and is continuous from the upper surface (the surface shown in Figure 4A) to the lower surface (the surface shown in Figure 4F). In the embodiment shown in Figures 4(A), (D) and 5, the tip of the slit is chamfered into a circular shape when viewed from the planar direction. It is preferable that the width of the slit when viewed from the planar direction (the horizontal length of the slit in Figure 4A) satisfies the following formula (3).
(D×N)×0.3≦slit width (μm)≦(D×N)×1.5 ... (3)
D: average filament diameter of warp or weft (μm)
N: Average number of filaments in the warp or weft

As described above, by making the focusing member have a slit structure and making the width of the slit small enough to satisfy the above formula (3), the glass yarn of the present invention described above can be manufactured.

Explaining in more detail with reference to FIG. 6, the spinning device 200 includes a sizing agent tray 201 that applies a sizing agent to the glass filaments 3 discharged from the nozzle 40, a bundling member 2 that bundles the glass filaments 3 into a predetermined number of glass filament bundles, a traverse mechanism 206 that traverses the glass filament bundles, and a winding roller 211 that winds up the glass filament bundles. The sizing agent tray 201 is provided with a sizing agent that is supplied to the sizing agent tray 201, and an applicator (not shown) that picks up the sizing agent and applies the sizing agent to the glass filaments 3 by contacting the picked-up sizing agent. Note that instead of the bundling tray 201, the sizing agent can be applied to the glass filaments 3 by spray injection or the like. The bundling member 2 is as described above. The fiber bundle 4 (glass strand) of filaments 3 gathered by the gathering member 2 is traversed by the traverse member 209 by the rotational drive of the traverse shaft 207, and is evenly wound on the winding roller 211. The winding roller 211 rotates about a predetermined rotation axis, and the rotation speed and rotational drive force are adjusted. As a result, the spinning tension (tensile tension) and spinning speed of the molten glass discharged from the nozzle 40 are adjusted to wind the fiber bundle. The obtained glass filament bundle is then twisted by a ring twisting machine or the like to produce a glass yarn. The glass yarn can be wound around a bobbin or the like to produce a glass yarn package in which the glass yarn is wound.

As shown in FIG. 7, the focusing member 2 with a slit structure can also be arranged so that the glass filaments are first focused by a conventional focusing member 1 and then the focused fiber bundle 4 passes through the focusing member 2.

The glass cloth of the present invention is woven using the above-mentioned glass yarn of the present invention as the warp and/or weft.

The thickness of the glass cloth of the present invention is not particularly limited, but may be, for example, 8 to 30 μm. The mass of the glass cloth of the present invention is not particularly limited, but may be, for example, 6 to 30 g/ ^m2 .

The glass yarn breakage detection method of the present invention includes the steps of running a single glass yarn to be measured and continuously photographing the glass yarn in the longitudinal direction, detecting the number of glass yarns from the photographed images, and judging a portion where the glass yarn is not twisted together and is partially divided into two or more strands as a yarn breakage.

A specific embodiment of the glass yarn breakage detection method of the present invention is a glass yarn breakage detection method using an inline projection image measuring device (product name) manufactured by Keyence Corporation, in which the glass yarn to be measured is continuously passed through the light projected and received by the measuring device to detect breakage in the glass yarn. Details of the measurement conditions are as described in the glass yarn breakage rate.

The present invention will be described in detail below with reference to examples and comparative examples. However, the present invention is not limited to the examples.

<Measurement method, etc.>
1. Average filament diameter and number of glass filaments The average filament diameter of the glass filaments was measured and calculated according to the method specified in the B method (cross-sectional method) of "7.6 Single fiber diameter" of "General test method for glass fibers" of the Japanese Industrial Standard JIS R 3420: 2013. Specifically, the glass yarn was embedded in an epoxy-based cold embedding resin (manufactured by Struers, product name Epoxy Resin Specifix-40) and cured to obtain a cured product. Next, the glass yarn embedded in the epoxy-based cold embedding resin was cured to an extent that it could be observed, and a sample was polished, and the average diameter was observed and measured at a magnification of 2000 times and the number of filaments was observed and measured at a magnification of 500 times using a scanning electron microscope (SEM) (manufactured by JEOL, product name JSM-6390A). Thirty glass yarns were randomly selected, and the diameters (largest part) of all the glass filaments in the 30 glass yarns were measured in the cross section, and the arithmetic mean value was calculated to be the average diameter of the glass filaments in the glass yarn. The number of glass filaments constituting the glass yarn was measured in the measurement of the average diameter of the glass filaments.

2. Glass yarn count The count was measured and calculated according to the method specified in "7.1 Count" of the Japanese Industrial Standard JIS R 3420: 2013 (General Test Method for Glass Fibers). Specifically, 500 m of glass yarn was taken from a bobbin on which the glass yarn was wound, and this was used as a test piece. The test piece was placed flat and placed in an oven, dried at 105°C for 60 minutes, and then cooled in a desiccator, and the mass of the test piece was measured. The count was calculated according to the following formula.
t=(m/500)×1000
t: number m: mass of test piece (g)

3. Ignition loss of glass yarn The ignition loss was measured according to the method specified in "7.3.2 Ignition loss" of "General test method for glass fibers" of Japanese Industrial Standard JIS R 3420 2013.

4. Yarn breakage rate of glass yarn A measuring instrument manufactured by Keyence Corporation (product name: inline projection image measuring instrument (TM-X5006 series sensor head (φ6 mm type)) was used, and the glass yarn was pulled out from the glass yarn package and continuously passed through the projected and received light. The running conditions when the glass yarn was passed through the projected and received light were a speed of 23 m/min and a tension of 0.001 (N) or less, and a portion where the glass yarn was partially divided into multiple strands in the longitudinal direction (a portion where the number of strands was two or more under the measurement conditions described below) was determined as a yarn breakage. The yarn breakage rate (%) was calculated by the number of broken strands/total number of measurements x 100. The measurement was performed using the analysis software attached to the above measuring instrument, and the software was set to the number of measurement tools. The detailed conditions when the number of measurement tools was set were as follows.
Tool name: Number tolerance setting Design value: 0001 Moving average: 1 Treatment setting Alarm hold count: 000 Scaling: Not set Offset: 0000 Zero reference value: 0000 Peak detection filter: None Hold mode: None Edge detailed setting Segment size: 0001
Interval: 0001
Sensitivity: 30%
Filter width: 010
・Strength lower limit: 010
・Outside area processing (high speed): Unchecked area specified ・Start point: X = 003.000 mm Y = 002.000 mm
End point: X = 003.000 mm Y = 005.167 mm
Detection width: 0.300 mm
Length: 3.167mm
・Position correction source: No. 1
Area adjustment during setting Reference: Arbitrary straight line Orientation: Parallel to reference Mask setting Mask area 1: None Mask area 2: None Mask area 3: None Mask area 4: None

5. Yarn width of glass yarn An in-line projection image measuring machine (TM-X5006 series sensor head (φ6 mm type)) manufactured by Keyence Corporation was used as a measuring instrument, and the glass yarn was pulled out from the glass yarn package and continuously passed through the projected and received light. The running conditions when the glass yarn was passed through the projected and received light were a speed of 23 m/min and a tension of 0.001 (N) or less. Measurements were performed using analysis software attached to the measuring instrument, with the measurement tool set to the average outer diameter as the software settings. The detailed conditions when the measurement tool was set to the average outer diameter were as follows:
Tool name: Average outer diameter measurement Contents: Average tolerance design Moving average: 1 time treatment setting Alarm hold count: 000 times Scaling: Unchecked Offset: 0000 Zero reference value: 0000 Peak detection filter: None Hold mode: None Decimal points: 3 digits Display unit: mm
Enable DIA correction: Checked Remove outliers: No Edge detail settings Segment size: 0001
Interval: 0001
Sensitivity: 10%
・Filter width: 005
・Strength minimum: 025
・Outside area processing (high speed): Unchecked area specified ・Start point: X = 003.000 mm Y = 002.000 mm
End point: X = 003.000 mm Y = 005.167 mm
Detection width: 0.300 mm
Length: 3.167mm
・Position correction source: No. 1
Area adjustment during setting Reference: Arbitrary straight line Orientation: Parallel to reference Mask setting Mask area 1: None Mask area 2: None Mask area 3: None Mask area 4: None

6. Fluff of Glass Yarn The glass yarn prepared in the manufacturing example was unwound at a speed of 100 m/min, and the number of fluffs was counted by a sensor after passing through a tension bar. The number of fluffs per 1 km (pieces/km) was calculated.

Example 1
A glass yarn was produced using a glass strand production apparatus as illustrated in FIG. 6. Specifically, a sizing agent was applied to a plurality of glass filaments spun from a spinning furnace using an applicator, and the glass filaments were passed through the slits of a bundling member having a slit structure as illustrated in FIG. 4 and FIG. 5 to bundle the glass filaments into one glass strand. Next, the glass strand was wound around a tube without being twisted to obtain a cake. Next, the obtained cake was dried. The dried cake was set in a ring twisting machine, and the glass strand was unwound and twisted while being wound around a bobbin to obtain a glass yarn. The slit width of the bundling member having a slit structure was set to 100 μm. In the obtained glass yarn, the average diameter of the glass filaments was 3.6 μm, the number of filaments was 38, the glass yarn count was 1.0 tex, the ignition loss was 1.2%, and the twist number was 0.5Z.

<Comparative Example 1>
A glass yarn was produced using a glass strand production apparatus as illustrated in FIG. 3. Specifically, a sizing agent was applied to a plurality of glass filaments spun from a spinning furnace using an applicator, and the glass filaments were focused into one glass strand by passing through a conventional focusing member (having a length 1L of a cylindrical portion 1a of 500 μm) as shown in FIG. 2. Next, the glass strand was wound around a tube without being twisted to obtain a cake. Next, the obtained cake was dried. The dried cake was set in a ring twisting machine, and the glass strand was unwound and twisted while being wound around a bobbin to obtain a glass yarn. In the obtained glass yarn, the average diameter of the glass filaments was 3.6 μm, the number of filaments was 38, the glass yarn count was 1.0 tex, the ignition loss was 1.2%, and the twist number was 0.5Z.

The physical properties of the glass yarns in Example 1 and Comparative Example 1 are shown in Table 1.

Comparing Example 1 and Comparative Example 1, which have the same average filament diameter, number of filaments, yarn count, and ignition loss, Example 1 had a glass yarn breakage rate of 7% or less, and was therefore able to suppress the generation of fuzz compared to Comparative Example 1.

Example 2
A glass yarn was produced using a glass strand production apparatus as illustrated in FIG. 6. Specifically, a sizing agent was applied to a plurality of glass filaments spun from a spinning furnace using an applicator, and the glass filaments were passed through the slits of a bundling member having a slit structure as illustrated in FIG. 4 and FIG. 5 to bundle the glass filaments into one glass strand. Next, the glass strand was wound around a tube without being twisted to obtain a cake. Next, the obtained cake was dried. The dried cake was set in a ring twisting machine, and the glass strand was unwound and twisted while being wound around a bobbin to obtain a glass yarn. The slit width of the bundling member having a slit structure was set to 100 μm. In the obtained glass yarn, the average diameter of the glass filaments was 4.1 μm, the number of filaments was 40, the glass yarn count was 1.3 tex, the ignition loss was 1.2%, and the twist number was 0.5Z.

<Comparative Example 2>
A glass yarn was produced using a glass strand production apparatus as illustrated in FIG. 3. Specifically, a sizing agent was applied to a plurality of glass filaments spun from a spinning furnace using an applicator, and the glass filaments were focused into one glass strand by passing through a conventional focusing member (having a length 1L of the cylindrical portion 1a of 500 μm) as shown in FIG. 2. Next, the glass strand was wound around a tube without being twisted to obtain a cake. Next, the obtained cake was dried. The dried cake was set in a ring twisting machine, and the glass strand was unwound and twisted while being wound around a bobbin to obtain a glass yarn. In the obtained glass yarn, the average diameter of the glass filaments was 4.1 μm, the number of filaments was 40, the glass yarn count was 1.3 tex, the ignition loss was 1.2%, and the twist number was 0.5Z.

The physical properties of the glass yarns in Example 2 and Comparative Example 2 are shown in Table 2.

Comparing Example 2 and Comparative Example 2, which have the same average filament diameter, number of filaments, yarn count, and ignition loss, Example 2 had a glass yarn breakage rate of 7% or less, and was therefore able to suppress the generation of fuzz compared to Comparative Example 2.

Example 3
A glass yarn was produced using a glass strand production apparatus as illustrated in FIG. 6. Specifically, a sizing agent was applied to a plurality of glass filaments spun from a spinning furnace using an applicator, and the glass filaments were passed through the slits of a bundling member having a slit structure as illustrated in FIG. 4 and FIG. 5 to bundle the glass filaments into one glass strand. Next, the glass strand was wound around a tube without being twisted to obtain a cake. Next, the obtained cake was dried. The dried cake was set in a ring twisting machine, and the glass strand was unwound and twisted while being wound around a bobbin to obtain a glass yarn. The slit width of the bundling member having a slit structure was set to 100 μm. In the obtained glass yarn, the average diameter of the glass filaments was 4.1 μm, the number of filaments was 50, the glass yarn count was 1.65 tex, the ignition loss was 1.2%, and the twist number was 0.5Z.

<Comparative Example 3>
A glass yarn was produced using a glass strand production apparatus as illustrated in FIG. 3. Specifically, a sizing agent was applied to a plurality of glass filaments spun from a spinning furnace using an applicator, and the glass filaments were focused into one glass strand by passing through a conventional focusing member (having a length 1L of the cylindrical portion 1a of 500 μm) as shown in FIG. 2. Next, the glass strand was wound around a tube without being twisted to obtain a cake. Next, the obtained cake was dried. The dried cake was set in a ring twisting machine, and the glass strand was unwound and twisted while being wound around a bobbin to obtain a glass yarn. In the obtained glass yarn, the average diameter of the glass filaments was 4.1 μm, the number of filaments was 50, the glass yarn count was 1.65 tex, the ignition loss was 1.2%, and the twist number was 0.5Z.

The physical properties of the glass yarns in Example 3 and Comparative Example 3 are shown in Table 3.

Comparing Example 3 and Comparative Example 3, which have the same average filament diameter, number of filaments, yarn count, and ignition loss, Example 3 had a glass yarn breakage rate of 7% or less, and therefore was able to suppress the generation of fuzz compared to Comparative Example 3.

Claims (6)

A glass yarn formed by bundling a plurality of glass filaments,
The average filament diameter is 4.7 μm or less;
The glass yarn has a yarn breakage rate of 7% or less. The glass yarn according to claim 1, wherein the number of glass filaments is 70 or less. The glass yarn according to claim 1, wherein the number of twists of the glass yarn is 0.3 to 1.2 times/25 mm. A glass cloth woven using the glass yarn according to any one of claims 1 to 3 as warp and/or weft. A method for producing a glass yarn according to any one of claims 1 to 3,
The method includes a step of focusing the glass filaments by a focusing member having a slit structure,
A method for producing a glass yarn, wherein the width of the slit satisfies the following formula:
(D×N)×0.3≦slit width (μm)≦(D×N)×1.5
D: average filament diameter of warp or weft (μm)
N: Number of filaments in the warp or weft A method for detecting breakage in glass yarn, comprising the steps of running a single glass yarn to be measured and continuously photographing the glass yarn in the longitudinal direction, detecting the number of glass yarns from the photographed images, and judging a portion where the glass yarn is not twisted together and is partially divided into two or more strands as a breakage.