Glass interleaving paper

Abstract

To provide a glass interleaving paper, which is a nonwoven fabric having preset bending strength.SOLUTION: A glass interleaving paper is a nonwoven fabric having thickness of 60 μm or more and 160 μm or less. A first test piece obtained by cutting the nonwoven fabric into the size of 20 mm×150 mm has 70 mm or less of drooping length measured by bending resistance measurement method specified by JIS-L1096-2010 Method B when extending length is 100 mm. Such a structure allows provision of the glass interleaving paper formed of a nonwoven fabric having preset bending strength while allowing thickness to be suppressed when glasses are layered. Consequently, occurrence of particles can be suppressed when the glass interleaving papers are layered, and glasses for which the glass interleaving paper are used can be held clean, and a layered body layered in a vertical posture can be handled.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to glass interleaving paper. More specifically, the present invention relates to glass interleaving paper that is a nonwoven fabric. [Background technology]

[0002] Glass interleaving paper is used by being sandwiched between glass sheets during the transportation of glass sheets, such as architectural glass sheets, automotive glass sheets, and glass sheets for liquid crystal displays. Among these glass sheets, glass sheets for flat panel displays, particularly those used in liquid crystal displays, have elements such as fine electrical wiring, electrodes, electrical circuits, and partition walls formed on their surfaces. Therefore, even slight scratches or contamination on the surface can cause defects such as disconnections. Therefore, high quality in terms of particle generation and the like is required for glass interleaving paper to prevent scratches or contamination. Recently, glass interleaving paper used in automotive glass sheets is also sometimes required to have the same quality as glass interleaving paper used in flat panel displays.

[0003] In order to solve the above problems, Patent Documents 1 and 2 disclose glass interleaving paper, which is a nonwoven fabric having a predetermined structure.

[0004] Furthermore, Patent Document 3 discloses a laminate in which glass plates and glass interleaving paper are alternately stacked in a vertical position on a pallet. Plate glass for flat panel displays has become larger as the size of the flat panel displays has increased, and in recent years, even when transporting a laminate, the glass plates are transported with the glass plates oriented vertically. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-2777991 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-173510 [Patent Document 3] Japanese Patent Application Publication No. 2022-143331 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when the thickness of a nonwoven fabric is the same, its bending strength, expressed as bending resistance, is generally lower than that of paper made from pulp. Figure 3 shows an explanatory diagram of a laminate 51 in which glass plates 52 and glass interleaving papers 53 are alternately stacked in a vertical position. It also shows an enlarged schematic diagram of the protruding portion of the glass interleaving paper 53. When the glass plates 52 become larger, i.e., when their area increases, stacking the glass plates 52 in a vertical position makes handling easier than stacking them in a horizontal position. Here, when the glass plates 52 are stacked in a vertical position on the conveyor 50, the glass interleaving paper 53 sandwiched between the glass plates 52 protrudes above the laminate 51 by approximately 100 mm. When the glass plates 52 are removed one by one from the stack 51, the glass interleaving papers 53 are also removed one by one. However, if the bending strength of the glass interleaving paper 53 is low, the protruding portions of the glass interleaving paper 53 will overlap with the protruding portions of adjacent glass interleaving papers 53, making it impossible to properly feed the gripping parts of the glass interleaving paper 53 between the glass interleaving papers 53, and making it impossible to remove the glass interleaving papers 53 one by one from the stack 51. For this reason, there is a problem in that glass interleaving paper 53 with a low bending strength is difficult to use for vertical conveyance.

[0007] In view of the above circumstances, an object of the present invention is to provide glass interleaving paper, which is a nonwoven fabric having a predetermined bending strength. [Means for solving the problem]

[0008] The glass interleaving paper of the first invention is a nonwoven fabric having a thickness of 60 μm or more and 160 μm or less, and is characterized in that a first test piece cut out of the nonwoven fabric, measuring 20 mm x 150 mm, has a hanging length of 70 mm or less when measured using the bending resistance measurement method specified in Method B of JIS-L1096-2010, when the overhang length is 100 mm. The glass interleaving paper of the second invention is characterized in that, in the first invention, the diameter of the fibers constituting the nonwoven fabric is 20 μm or more. The glass interleaving paper of the third invention is characterized in that, in the first or second invention, the nonwoven fabric is cut into a 295 mm x 208 mm second test piece that has not been washed, and the number of separable particles per second measured using the tumbling method of JIS-B9923-1997 is 10 or less particles that are 0.3 μm or more and smaller than 0.5 μm, 20 or less particles that are 0.5 μm or more and smaller than 1.0 μm, and 20 or less particles that are 1.0 μm or more and smaller than 5.0 μm. [Effects of the Invention]

[0009] According to the first invention, the bending strength value when the thickness is equal to or less than a predetermined value is 70 mm, so that it is possible to provide glass interleaving paper made of a nonwoven fabric with a predetermined bending strength while suppressing the thickness when glass is laminated. This makes it possible to suppress particle generation during lamination of the glass interleaving paper, keep the glass to which the glass interleaving paper is applied clean, and make it possible to handle the laminated body in a vertical position. According to the second aspect of the present invention, the diameter of the fibers constituting the nonwoven fabric is 20 μm or more, so that the bending strength can be further increased while the thickness of the nonwoven fabric is maintained at a thin state. According to the third aspect of the present invention, the number of particles in the nonwoven fabric is equal to or less than a predetermined number, so that when the nonwoven fabric is used as glass interleaving paper, the glass can be kept cleaner. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 2 is an explanatory diagram of a method for measuring the bending strength of a nonwoven fabric. [Figure 2] FIG. 2 is an explanatory diagram of measurement points when measuring the thickness of a nonwoven fabric. [Figure 3] 1 is an explanatory diagram of a laminate in which glass plates and glass interleaving paper are alternately stacked in a vertical position, and an enlarged schematic diagram of a protruding portion of the glass interleaving paper. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, embodiments of the present invention will be described with reference to the drawings. However, the embodiments shown below are examples of glass interleaving paper for embodying the technical concept of the present invention, and the present invention does not limit the glass interleaving paper to the following. Furthermore, unless otherwise specified, the dimensions, materials, shapes, etc. of the components described in the embodiments are merely illustrative examples and are not intended to limit the scope of the present invention. Furthermore, the sizes or positional relationships of the components shown in each drawing may be exaggerated for clarity.

[0012] The glass interleaving paper of the present invention is a nonwoven fabric having a thickness of 60 μm or more and 160 μm or less, and a first test piece 20 cut out of the nonwoven fabric to a size of 20 mm x 150 mm has a hanging length of 70 mm or less when measured using the bending resistance measurement method specified in Method B of JIS-L1096-2010 when the overhang length is 100 mm.

[0013] By limiting the hanging length to 70 mm or less when the thickness of the glass interleaving paper is within a predetermined thickness range, it is possible to provide glass interleaving paper made of nonwoven fabric with a predetermined bending strength while suppressing the thickness when the glass is laminated. This makes it possible to suppress particle generation during lamination of the glass interleaving paper, keep the glass to which the glass interleaving paper is applied clean, and enable handling of the laminated product in a vertical position.

[0014] Furthermore, it is preferable that the diameter of the fibers constituting the nonwoven fabric is 20 μm or more. By making the diameter of the fibers constituting the nonwoven fabric 20 μm or more, the bending strength can be further increased while the thickness of the nonwoven fabric is maintained at a thin state.

[0015] Furthermore, when a second test piece of the nonwoven fabric that has been cut to a size of 295 mm x 208 mm and has not been laundered is measured using the tumbling method of JIS-B9923-1997, the number of separable particles per second is preferably 10 or less for particles that are 0.3 μm or more and smaller than 0.5 μm, 20 or less for particles that are 0.5 μm or more and smaller than 1.0 μm, and 20 or less for particles that are 1.0 μm or more and smaller than 5.0 μm. By keeping the number of particles in the nonwoven fabric at a predetermined number or less, when the nonwoven fabric is used as glass interleaving paper, the glass can be kept cleaner.

[0016] <Embodiment> (Thickness of nonwoven fabric) Most conventional glass interleaving papers are made from pulp and are required to be between 60 μm and 160 μm thick. This is because if the thickness of the glass interleaving paper is thinner than 60 μm, there is a high possibility that the glass sheets will come into contact with each other when stacked. Also, if the thickness of the glass interleaving paper is thicker than 160 μm, the height in the stacking direction will be too high when several dozen sheets of glass are stacked. Therefore, the required thickness of the nonwoven fabric that will be used as the glass interleaving paper is between 60 μm and 160 μm.

[0017] The thickness of the nonwoven fabric according to this embodiment conforms to the "thickness" test method A specified in JIS-L1913-2010. FIG. 2 also shows an explanatory diagram of measurement locations for measuring the thickness of the nonwoven fabric. FIG. 2 shows a rectangular test piece 30 measuring 150 mm x 100 mm. For example, five locations on the test piece 30 are measured as shown in the figure, and thickness measurements are obtained for each location. The average of these measurements can be used as the thickness of the test piece 30, i.e., the thickness of the nonwoven fabric. This is because the thickness of a nonwoven fabric varies depending on the measurement location.

[0018] (Bending strength of nonwoven fabric) FIG. 1 is an explanatory diagram of a method for measuring the bending strength of a nonwoven fabric used as glass interleaving paper. FIG. 1 shows a front view of a testing machine 10. This testing machine 10 is an example of a testing machine specified in JIS-L1096-2010, Method B. The thickness of the nonwoven fabric was measured in accordance with JIS-L1913-2010, "General Nonwoven Fabric Testing Methods," while the bending strength of the nonwoven fabric used as glass interleaving paper was measured in accordance with JIS-L1096-2010, "Testing Methods for Woven and Knit Fabrics," Method B. Glass interleaving paper is sometimes sandwiched between glass and glass using static electricity. In this case, a material that easily becomes statically charged is used for the glass interleaving paper. This causes the first test piece 20 to easily become statically charged, making it difficult to accurately measure bending strength using the method specified in JIS-L1913-2010, "General Nonwoven Fabric Testing Methods."

[0019] The testing machine 10 has a configuration in which a pillar-shaped column 12 is erected on a flat base 11. A movable stage 13 that moves up and down along the side of the column 12 is provided for the column 12. The base 11 is adjusted so that the top surface of the movable stage 13 is horizontal. The movable stage 13 is fixed to the column 12 by a knob 15 provided on the column 12. The knob 15 is located opposite the side of the column 12 on which the movable stage 13 is provided. The column 12 is provided with a scale 14 that indicates the distance of the movable stage 13 from the top of the column 12.

[0020] The user of the testing machine 10 cuts the nonwoven fabric to be measured into a size of 20 mm x 150 mm to prepare the first test piece 20 to be measured. The longitudinal direction of the first test piece 20 preferably coincides with the longitudinal direction of the entire nonwoven fabric, i.e., coincides with the direction perpendicular to the width direction of the entire nonwoven fabric. When forming the laminate 50 as shown in Figure 3, the laminate 50 is often fed from above, and it is therefore preferable that the vertical direction of the protruding portion of the glass interleaving paper 53 coincides with the longitudinal direction of the first test piece 20.

[0021] The user of the testing machine 10 loosens the knob 15 and moves the movable stage 13 to a position where its top surface is flush with the top surface of the column 12. Then, in this state, the user tightens the knob 15 to secure the movable stage 13. Next, the user places the first test piece 20 on the top surface of the column 12. At this time, the user places the first test piece 20 so that it overhangs by a predetermined length, such that the overhang length l of the first test piece 20, i.e., the length overhanging the movable stage 13 side, is 100 mm, for example. Then, the user places a weight 16 on the end of the column 12 to secure the first test piece 20. It is preferable to place the weight 16 so that it overhangs slightly toward the movable stage 13 side. The user then loosens the knob 15 and moves the movable stage 13 downward. The user then secures the movable stage 13 to the column 12 with the knob 15 at a height where the free end of the first test piece 20 is separated from the movable stage 13, and measures the hanging length b.

[0022] In the glass interleaving paper according to this embodiment, the first test piece 20 cut out from the nonwoven fabric to a size of 20 mm x 150 mm has a drooping length of 70 mm or less, measured by the bending resistance measurement method specified in Method B of JIS-L1096-2010, when the overhang length is 100 mm. A small drooping length indicates a high bending strength, while a large drooping length indicates a low bending strength. The drooping length is preferably 0 mm, but it is unlikely to be 0 mm as long as the nonwoven fabric has weight. However, a drooping length of 30 mm or more is preferable because it allows the gripping parts for gripping the glass interleaving paper to be accurately positioned between the glass interleaving papers. If the drooping length is greater than 70 mm, when a glass laminate is formed in a vertical orientation, the glass interleaving papers may overlap, making it difficult for the gripping parts for removing the glass interleaving paper to be inserted between the glass interleaving papers.

[0023] By limiting the hanging length of the glass interleaving paper to 70 mm or less when the thickness is less than the specified value, it is possible to provide glass interleaving paper made of nonwoven fabric with a predetermined bending strength while suppressing the thickness when the glass is laminated. This makes it possible to suppress particle generation during lamination of the glass interleaving paper, keep the glass to which the glass interleaving paper is applied clean, and enable handling of the laminate in a vertical position.

[0024] (Nonwoven fabric material) The material of the nonwoven fabric that constitutes the glass interleaving paper according to this embodiment is not particularly limited. For example, aramid fiber, glass fiber, cellulose fiber, nylon fiber, vinylon fiber, polyester fiber, polyethylene fiber, polypropylene fiber, polyolefin fiber, rayon fiber, etc. can be used as appropriate. A combination of these fibers may also be used. Among these, the glass interleaving paper according to this embodiment preferably comprises deposited polyester fiber. The deposited continuous fibers are preferably thermally bonded together. The use of thermoplastic synthetic fiber, polyester, as a component of the continuous fibers allows for inexpensive and efficient production of the glass interleaving paper. Furthermore, polyester fiber has the advantages of excellent strength and moderate hydrophilicity, making it less likely to become electrically charged in the air and less likely to attract dust particles in the air.

[0025] The polyester used as the material for the nonwoven fabric of the glass interleaving paper according to this embodiment is a polycondensation product of a polycarboxylic acid (dicarboxylic acid) and a polyalcohol (diol). There are no particular limitations on the polyester, as long as it is obtained by dehydration condensation of a polyalcohol (a compound having multiple alcoholic functional groups -OH) and a polycarboxylic acid (a compound having multiple carboxylic acid functional groups -COOH). For example, polyethylene terephthalate or polybutylene terephthalate obtained from terephthalic acid as the polycarboxylic acid (acid component) and ethylene glycol or butanediol as the polyalcohol (glycol component) is preferably used. The acid component may also be a copolymer of terephthalic acid and another acid component. The glycol component may also be a copolymer of ethylene glycol and another glycol component. Examples of other acid components include aromatic dicarboxylic acids such as isophthalic acid, diphenyl ether-4,4'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, and naphthalene-2,6-dicarboxylic acid; aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, and undecadicarboxylic acid; and alicyclic dicarboxylic acids such as hexahydroterephthalic acid. Examples of other glycol components include aliphatic glycols such as propylene glycol and neopentyl glycol; alicyclic glycols such as cyclohexanedimethanol; and aromatic dihydroxy compounds such as bisphenol A. As the polyester, only one type of polyester may be used, or a blend of homopolymers or a blend of a homopolymer and a copolymer may also be used.

[0026] In the nonwoven fabric that is the glass interleaving paper according to this embodiment, polyesters that are preferably used are polyesters in which the acid component is an aromatic dicarboxylic acid and the glycol component is a linear diol, such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polybutylene naphthalate, because the polyesters have excellent mechanical strength, heat resistance, and flexibility.

[0027] Additives can be blended into the polyester as needed. Additives that can be blended include antistatic agents, colorants, flexibility agents, antioxidants, heat stabilizers, weathering agents, metal deactivators, light stabilizers, antibacterial and antifungal agents, dispersants, softeners, plasticizers, nucleating agents, flame retardants, foaming agents, and foaming aids. However, additives that bleed out from the polyester or that produce powder or dust and fall off should not be blended.

[0028] The fibers constituting the nonwoven fabric that is the glass interleaving paper according to this embodiment may be single-phase fibers made of one type of polyester, or composite fibers made of two or more polyesters, either the same or different types. Furthermore, it does not matter if the fibers are a mixture of single-phase fibers made of different polyesters, composite fibers made of a combination of different polyesters, or a mixture of single-phase fibers and composite fibers.

[0029] (Nonwoven fiber manufacturing method and fiber diameter) The fibers used in the nonwoven fabric that is the glass interleaving paper according to this embodiment are preferably continuous fibers. This is because fiber shedding does not occur. Examples of nonwoven fabrics formed by the accumulation of continuous fibers include spunbond nonwoven fabrics, meltblown nonwoven fabrics, and flash-spun nonwoven fabrics. Spunbond nonwoven fabrics are preferred because of their excellent single fiber strength, good sheet dimensional stability, a small single fiber fineness that reduces the contact area with the glass plate, and the fact that no solvents are used during production. Furthermore, the diameter of the fibers constituting the nonwoven fabric is preferably 20 μm or more. For example, when producing continuous fibers for use in nonwoven fabrics using the spunbond method, the diameter of the fibers can be made the same as the diameter of the mold hole, 20 μm or more, by setting the hole diameter of the mold through which the fibers are injected to 20 μm or more. Furthermore, the fibers of the nonwoven fabric can also have a so-called sheath-core structure. When the fibers have a sheath-core structure, the diameter of the fibers can be easily increased. There is no particular upper limit to the diameter of the fibers constituting the nonwoven fabric, but in consideration of handling after production, the diameter of the fibers constituting the nonwoven fabric is preferably 40 μm or less.

[0030] By making the diameter of the fibers constituting the nonwoven fabric that is the glass interleaving paper according to this embodiment 20 μm or more, it is possible to further increase the bending strength while maintaining the thickness of the nonwoven fabric thin.

[0031] (Amount of dust generated by nonwoven fabric) When a 295 mm x 208 mm specimen of the nonwoven fabric used as the glass interleaving paper according to this embodiment is prepared and not laundered, the number of separable particles per second measured using the tumbling method of JIS-B9923-1997 is preferably 10 or fewer particles smaller than 0.3 μm and 0.5 μm, 20 or fewer particles smaller than 0.5 μm and 1.0 μm, and 20 or fewer particles smaller than 1.0 μm and 5.0 μm. JIS-L1913-2010, "General Nonwoven Fabric Testing Method," does not specify a method for measuring the dust generation of nonwoven fabrics. Therefore, the measurement specified in JIS-B9923-1997, "Method for Measuring Contaminant Particles in Cleanroom Clothing," is applied mutatis mutandis to determine the amount of dust generated by the nonwoven fabric.

[0032] By keeping the number of particles in the nonwoven fabric at or below a predetermined number, when the nonwoven fabric is used as glass interleaving paper, the glass can be kept cleaner. [Example]

[0033] Specific examples of the glass interleaving paper according to the present invention will be described below, but the present invention is not limited to these examples.

[0034] (Examples of thickness, basis weight, hanging length, and fiber thickness) Example 1 A nonwoven fabric was manufactured using polyethylene terephthalate with a core-sheath structure of continuous fibers. The thickness of this nonwoven fabric was measured using the "thickness" test method A specified in JIS-L1913-2010. A rectangular test piece 30 measuring 150 mm x 100 mm was used for the measurement, and the thickness was measured at five locations as shown in Figure 2, with the average value being used as the measured value. The measured thickness was 109.2 μm. The basis weight of the nonwoven fabric, i.e., the weight per square meter of this nonwoven fabric, was 20 g. The values ​​are shown in Table 1.

[0035] Next, the nonwoven fabric was cut into 20 mm x 150 mm strips with the longitudinal direction aligned with the longitudinal direction of the entire nonwoven fabric to prepare first test pieces 20. The bending resistance measurement method specified in JIS-L1096-2010, Method B, was used to measure the hanging length of each first test piece 20 twice, on the front and back, when the overhang length was 100 mm, and the average of these measurements was used as the measured value. The measured hanging length was 52.9 mm, confirming sufficient bending strength. The values ​​are shown in Table 1.

[0036] Finally, the fiber thickness of this nonwoven fabric was measured using a digital microscope. Five 20 mm x 150 mm first test pieces 20 were prepared, and each first test piece 20 was measured twice at a magnification of 200x. The average value of the total 10 measurements was used as the measured fiber thickness. The measured fiber thickness was 25.28 μm, confirming that the fiber had a sufficient thickness. The values ​​are shown in Table 1.

[0037] Example 2 The differences between Example 1 and Example 2 are the thickness, basis weight, and fiber thickness after production. Other production conditions are the same as in Example 1. The methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Example 2 was 120.8 μm. The basis weight was 25 g. The values ​​are shown in Table 1.

[0038] In Example 2, the measured hanging length was 48.5 mm, confirming that the fiber had sufficient bending strength. Additionally, the measured fiber thickness was 29.70 μm, confirming that the fiber had sufficient thickness. The values ​​are shown in Table 1.

[0039] (Comparative Example 1) The differences between Example 1 and Comparative Example 1 are the thickness, basis weight, and fiber thickness after production. In addition, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. In addition, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 1 was 168.9 μm. The basis weight was 35 g. The values ​​are shown in Table 1.

[0040] In Comparative Example 1, the measured hanging length was 73.8 mm, confirming that the bending strength was low. The measured fiber thickness in this case was 14.75 μm, which was insufficient. Furthermore, in Comparative Example 1, the thickness was greater than the standard value of 160 μm, and it was found that in the case of this glass interleaving paper, the stacking height would exceed the specified value when stacked. The values ​​are shown in Table 1.

[0041] (Comparative Example 2) The differences between Example 1 and Comparative Example 2 are the thickness, basis weight, and fiber thickness after production. Furthermore, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. Furthermore, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 2 was 169.4 μm. The basis weight was 30 g. The values ​​are shown in Table 1.

[0042] In Comparative Example 2, the measured hanging length was 73.4 mm, confirming that the bending strength was low. The measured fiber thickness in this case was 18.41 μm, which was insufficient. Furthermore, in Comparative Example 2, the thickness was greater than the standard value of 160 μm, and it was found that in the case of this glass interleaving paper, the stacking height would exceed the specified value when stacked. The values ​​are shown in Table 1.

[0043] (Comparative Example 3) The differences between Example 1 and Comparative Example 3 are the thickness, basis weight, and fiber thickness after production. In addition, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. In addition, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 3 was 181.0 μm. The basis weight was 35 g. The values ​​are shown in Table 1.

[0044] In Comparative Example 3, the measured hanging length was 69.1 mm, confirming sufficient bending strength. However, the measured fiber thickness was 17.91 μm, which was insufficient. Furthermore, in Comparative Example 3, the thickness was greater than the standard value of 160 μm, and it was found that in the case of this glass interleaving paper, the stacking height would exceed the specified value when stacked. The values ​​are shown in Table 1.

[0045] Comparative Example 4 The differences between Example 1 and Comparative Example 4 are the thickness, basis weight, and fiber thickness after production. In addition, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. In addition, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 4 was 186.6 μm. The basis weight was 40 g. The values ​​are shown in Table 1.

[0046] In Comparative Example 4, the measured hanging length was 63.6 mm, confirming sufficient bending strength. However, the measured fiber thickness was 13.53 μm, which was insufficient. Furthermore, in Comparative Example 4, the thickness was greater than the standard value of 160 μm, and it was found that in the case of this glass interleaving paper, the stacking height would exceed the specified value when stacked. The values ​​are shown in Table 1.

[0047] (Comparative Example 5) The differences between Example 1 and Comparative Example 5 are the thickness, basis weight, and fiber thickness after production. In addition, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. In addition, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 5 was 192.5 μm. The basis weight was 45 g. The values ​​are shown in Table 1.

[0048] In Comparative Example 5, the measured hanging length was 61.0 mm, confirming sufficient bending strength. However, the measured fiber thickness was 12.82 μm, which was insufficient. Furthermore, in Comparative Example 5, the thickness was greater than the standard value of 160 μm, and it was found that in the case of this glass interleaving paper, the stacking height would exceed the specified value when stacked. The values ​​are shown in Table 1.

[0049] (Comparative Example 6) The differences between Example 1 and Comparative Example 6 are the thickness, basis weight, and fiber thickness after production. In addition, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. In addition, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 6 was 197.1 μm. The basis weight was 45 g. The values ​​are shown in Table 1.

[0050] In Comparative Example 6, the measured hanging length was 45.4 mm, confirming sufficient bending strength. However, the measured fiber thickness was 16.37 μm, which was insufficient. Furthermore, in Comparative Example 6, the thickness was greater than the standard value of 160 μm, and it was found that in the case of this glass interleaving paper, the stacking height would exceed the specified value when stacked. The values ​​are shown in Table 1.

[0051] (Comparative Example 7) The differences between Example 1 and Comparative Example 7 are the thickness and fiber thickness after production. In addition, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. In addition, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 7 was 117.7 μm. The basis weight was 20 g. The values ​​are shown in Table 1.

[0052] In Comparative Example 7, the thickness was found to be sufficiently thin, being less than the standard value of 160 μm. However, the measured hanging length was 100.9 mm, confirming that the bending strength was low. The measured fiber thickness was 14.34 μm, which was not sufficient. The values ​​are shown in Table 1.

[0053] (Comparative Example 8) The differences between Example 1 and Comparative Example 8 are the thickness, basis weight, and fiber thickness after production. In addition, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. In addition, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 8 was 129.8 μm. The basis weight was 25 g. The values ​​are shown in Table 1.

[0054] In Comparative Example 8, the thickness was found to be sufficiently thin, being less than the standard value of 160 μm. However, the measured hanging length was 91.2 mm, confirming that the bending strength was low. The measured fiber thickness was 15.60 μm, which was not sufficient. The values ​​are shown in Table 1.

[0055] Comparative Example 9 The differences between Example 1 and Comparative Example 9 are the thickness, basis weight, and fiber thickness after production. In addition, the fiber structure is a single fiber structure rather than a core-sheath structure. The other production conditions are the same as in Example 1. In addition, the methods for measuring the thickness, hanging length, and fiber thickness are the same as in Example 1. The measured thickness in Comparative Example 9 was 156.3 μm. The basis weight was 30 g. The values ​​are shown in Table 1.

[0056] In Comparative Example 9, the thickness was found to be sufficiently thin, being less than the standard value of 160 μm. However, the measured hanging length was 86.2 mm, confirming that the bending strength was low. The measured fiber thickness was 13.09 μm, which was not sufficient. The values ​​are shown in Table 1.

[0057] (Reference example 1) The difference between Example 1 and Reference Example 1 is that Example 1 is a nonwoven fabric, while Reference Example 1 is a paper made from pulp. In other words, the concept of fiber thickness does not exist in Reference Example 1. In addition, the difference between Example 1 and Reference Example 1 is the thickness and basis weight after production. The methods for measuring the thickness, hanging length, and fiber thickness were the same as those in Example 1. The measured thickness in Reference Example 1 was 83.2 μm. The basis weight was 50 g. The values ​​are shown in Table 1.

[0058] In Reference Example 1, the measured hanging length was 41.3 mm, which confirmed that the sample had sufficient bending strength. The values ​​are shown in Table 1.

[0059] [Table 1]

[0060] Glass interleaving papers were prepared for each of the examples and comparative examples, and the positions of adjacent glass interleaving papers after stacking were visually inspected. The glass interleaving papers of Examples 1 and 2 had sufficient space between adjacent pieces of glass interleaving paper, allowing the gripping parts of the glass interleaving paper to be easily inserted between the pieces of glass interleaving paper. In contrast, the glass interleaving papers of Comparative Examples 1 to 6 were thicker, resulting in a thicker laminate. Furthermore, in Comparative Examples 7 to 9, the pieces of glass interleaving paper stuck together, making it sometimes impossible to insert the gripping parts of the glass interleaving paper between adjacent pieces of glass interleaving paper.

[0061] (Examples regarding the amount of dust generated by nonwoven fabric) For Example 1 and Comparative Example 1, a second test piece was prepared and measured for the amount of dust generated by the nonwoven fabric. The amount of dust generated by the nonwoven fabric was determined by measurement using the tumbling method specified in JIS-B9923-1997 "Method for measuring contaminant particles in cleanroom clothing."

[0062] Example 1 A second test piece of nonwoven fabric measuring 295 mm x 208 mm was prepared. This sample was not washed. The amount of dust generated from this second sample was determined using a tumbling dust generation tester CW-HDT-102 manufactured by Akado Seisakusho Co., Ltd. The drum rotation speed of the test device was 30 RPM, and the flow rate was 0.0102 m 3 The speed was 1 / s, the suction volume was 1 cubic feet / m, and the particle counter used was a Hach Ultra Analytics Met One A2400B. The measurement results showed that the number of particles that could be separated per second was 1.3 for particles between 0.3 μm and 0.5 μm, 3.7 for particles between 0.5 μm and 1.0 μm, and 2.0 for particles between 1.0 μm and 5.0 μm. These values ​​were confirmed to be lower than the standard values ​​for pulp-based paper: 10 for particles between 0.3 μm and 0.5 μm, 20 for particles between 0.5 μm and 1.0 μm, and 20 for particles between 1.0 μm and 5.0 μm. The values ​​are shown in Table 2.

[0063] (Comparative Example 1) The differences between Example 1 and Comparative Example 1 are the thickness, basis weight, and fiber thickness after production. The fiber structure is a single fiber structure, not a core-sheath structure. Other production conditions are the same as in Example 1. The method for measuring the amount of dust generated is the same as in Example 1. The measurement results showed that the number of separable particles per second was 13.8 for particles of 0.3 μm or more and less than 0.5 μm, 22.3 for particles of 0.5 μm or more and less than 1.0 μm, and 28.5 for particles of 1.0 μm or more and less than 5.0 μm, all of which exceeded the standard values ​​for paper made from pulp. The values ​​are shown in Table 2.

[0064] [Table 2] [Explanation of symbols]

[0065] 10 Testing Machine 11. Base 12 Column 13 Mobile stand 14 scale 15 Knob 16 weights 20 test specimens b Hanging length l Overhang length

Claims

1. A nonwoven fabric having a thickness of 60 μm or more and 160 μm or less, A first test piece cut out from the nonwoven fabric measuring 20 mm x 150 mm has a hanging length of 70 mm or less when measured by the bending resistance measurement method specified in Method B of JIS-L1096-2010, when the overhang length is 100 mm. A glass interleaving paper characterized by:

2. The diameter of the fibers constituting the nonwoven fabric is 20 μm or more. The glass interleaving paper according to claim 1 .

3. a second test piece cut out from the nonwoven fabric measuring 295 mm x 208 mm and not subjected to a washing treatment, the number of separable particles per second measured using the tumbling method of JIS-B9923-1997 is 10 or less particles having a size of 0.3 μm or more and less than 0.5 μm, 20 or less particles having a size of 0.5 μm or more and less than 1.0 μm, and 20 or less particles having a size of 1.0 μm or more and less than 5.0 μm; 3. The glass interleaving paper according to claim 1 or 2.

Images