Interleaving paper for glass plates, glass plate laminate, and glass plate package

Abstract

To provide slip paper for a glass plate that is compatible with a higher definition display and is capable of decreasing the particles sticking to a glass plate and suppressing scratches from appearing on the surface of the glass plate.SOLUTION: The present invention relates to slip paper for a glass plate, which is characterized in that the thickness thereof is not smaller than 30 μm and not larger than 150 μm, the smoothness of at least one of the main surfaces of the slip paper for a glass plate is not less than 20 seconds, and the compression modulus K thereof is not lower than 1.0 MPa and not higher than 8.5 MPa; a glass plate laminate; and a glass plate package.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an interleaving paper for glass plates, a glass plate laminate, and a glass plate package. [Background technology]

[0002] For example, in glass plates used in flat panel displays such as LCDs (Liquid Crystal Displays) and OLEDs (Organic Light-Emitting Diodes), minute electronic components are formed on the surface of the glass plate, and even slight scratches or stains on the surface can cause defects such as broken wires, etc. Therefore, high cleanliness is required for the surface of the glass plate.

[0003] In order to improve transportation efficiency, glass plates are transported in a stacked state. At this time, glass plate interleaving paper (hereinafter also referred to as "interleaving paper") is placed between the glass plates to prevent scratches on the surface of the glass plates during transportation.

[0004] However, because glass plates are laminated with their surfaces pressed against the interleaf paper, particles such as paper dust and foreign matter generated from the interleaf paper may adhere to the surface of the glass plate, and the surface of the glass plate may be scratched, mainly by inorganic foreign matter in the interleaf paper. Therefore, there is a need for interleaf paper for glass plates that is less likely to allow particles to adhere to the surface of the glass plate and that can prevent scratches from occurring on the glass plate.

[0005] Patent Document 1 discloses an interleaf paper for glass plates having a hardened and non-hardened processed portion, and aims to suppress particle generation by setting the smoothness of the hardened processed portion to 20 seconds or more. Patent Document 2 also aims to reduce scratches on glass plates by setting the smoothness to 70 seconds or more.

[0006] However, with the recent trend toward higher resolution displays, the width and pitch of wiring formed on the surface of glass plates have become finer than before, and the quality required for the surface of glass plates has become higher. Therefore, even when the glass plate interleaving papers described in Patent Documents 1 and 2 are used, problems such as the adhesion of particles to the glass plates and scratches on the glass plate surfaces causing breakage of the wiring on the glass plates have arisen, and there has been a need to improve the quality of the glass plate interleaving paper. Therefore, in addition to the above-mentioned conventional techniques, many interleaving papers for glass sheets have been proposed that suppress scratches on the surface of glass sheets. One example is the interleaving paper for glass sheets disclosed in Patent Document 3, which specifies the content of minerals with a predetermined Mohs hardness or higher. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-034843 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-035125 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-006240 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the case of glass plates used in high-definition displays, problems may arise even if an interleaf paper containing only foreign matter having a Mohs hardness of a predetermined value or less is used. After extensive research, the inventors discovered that even if only foreign matter having a Mohs hardness of a predetermined value or less is present, scratches may occur on the glass plate due to the high particle strength of the foreign matter.

[0009] The present invention aims to provide an interleaving paper for glass plates that can reduce particle adhesion to glass plates and suppress the occurrence of scratches on the surface of the glass plates in response to the trend toward higher resolution displays. [Means for solving the problem]

[0010] (1) The glass plate interleaf paper according to the present invention is characterized in that it has a thickness of 30 μm or more and 150 μm or less, a smoothness of at least one main surface of the glass plate interleaf paper of 20 seconds or more, and a compressive elastic modulus K measured on the main surface of 1.0 MPa or more and 8.5 MPa or less. (2) The glass plate interleaving paper according to (1), wherein the arithmetic mean height Sa of the main surface is 2.5 μm or more. (3) The glass plate interleaving paper according to (1) or (2), wherein the maximum height Sz of the main surface is 45 μm or more. (4) The density of the glass plate interleaf is 0.4 (g / cm 3 ) or more 1.6 (g / cm 3 ) or less, and the smoothness of the main surface is 20 seconds or more and 400 seconds or less. (5) The sheet resistance of the glass plate interleaf is 5.0 × 10 10 (Ω / □) or more 5.0×10 13 The glass plate interleaving paper according to any one of (1) to (4), having a hardness of Ω / □ or less. (6) The compressive elastic modulus K (MPa), the number N (pieces / m) of foreign particles having an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more contained in the glass plate interleaf paper 2 6. The glass plate interleaving paper according to any one of (1) to (5), having a hard foreign matter resistance value KN, which is the product of (a) and (b), of 35.0 or less. (7) The compressive elastic modulus K (MPa), the number N (pieces / m) of foreign particles having an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more contained in the glass plate interleaf paper 2 7. The glass plate interleaving paper according to any one of (1) to (6), having a hard foreign matter resistance value KN, which is the product of (a) and (b), of 15.0 or less. (8) The interleaving paper for glass plates according to any one of (1) to (7), wherein the main surface is a surface that contacts a surface of the glass plate on which an electronic circuit is formed. (9) A glass plate laminate in which at least two glass plates are laminated, the glass plate laminate having the glass plate interleaving paper according to any one of (1) to (8) between the glass plates. (10) A glass plate package comprising the glass plate laminate according to (9) and a pallet on which the glass plate laminate is placed. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide an interleaf paper for glass plates that can suppress adhesion of particles to glass plates and the occurrence of scratches on the surface of the glass plates in response to the trend toward higher resolution displays. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a diagram showing the relationship between Mohs hardness and particle strength. [Figure 2] FIG. 2 is a conceptual diagram showing one embodiment of a method for producing interleaf paper for glass plates. [Figure 3] FIG. 3 is a cross-sectional view showing one embodiment of a pallet on which a glass plate is placed. [Figure 4] FIG. 4 is a cross-sectional view showing one embodiment of a glass plate package. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, preferred embodiments of the glass plate interleaf paper according to the present invention will be described. The embodiments shown below are merely examples, and the present invention should not be construed as being limited to these embodiments. Note that the glass plate is also referred to as a glass substrate.

[0014] From the viewpoint of transportation efficiency, glass plates are transported in a state in which at least two glass plates are stacked and placed on a pallet. A stack of at least two glass plates is called a glass plate laminate, and a glass plate laminate placed on a pallet is called a glass plate package.

[0015] In a glass plate laminate, when glass plates come into contact with each other, scratches may occur on the surfaces of the glass plates. It is known that if such scratches occur on the surfaces of the glass plates on which electronic circuits are formed, problems such as disconnections may occur. Therefore, by interposing a glass plate interleaf paper between the glass plates, scratches on the surfaces of the glass plates on which electronic circuits are formed can be prevented.

[0016] However, there is a risk that particles generated from the interleaf paper may adhere to the glass plates during storage or transportation, or that the surface of the glass plates may be scratched, mainly by inorganic foreign matter in the interleaf paper. With the recent trend toward higher resolution displays, the width and pitch of wiring formed on the surface of glass plates have become finer than ever before, and the quality required for the surface of glass substrates has become higher. Therefore, even when glass plate interleaf paper is used, problems such as breakage of wiring on glass plates, which were not a problem in the past, have begun to occur.

[0017] The present inventors have found that by increasing the smoothness of the slip sheet to a certain level or higher, defects caused by particle adhesion can be suppressed even in high-resolution displays. However, even when the smoothness of the slip sheet is increased and the amount of particle adhesion is reduced, scratches on the glass plate surface can still be a problem. Therefore, it is necessary to suppress particle adhesion and the occurrence of scratches on the glass plate surface.

[0018] Therefore, the present inventors investigated scratches that cause defects such as disconnections. As a result, they found that foreign matter having an average diameter of 10 μm or more and a particle strength C of 15 (MPa) or more is the cause. In particular, scratches caused by foreign matter having an average diameter of 10 μm to 50 μm and a particle strength C of 15 (MPa) or more have not traditionally been considered a problem. However, as the quality required for the surface of glass substrates has increased with the trend toward higher resolution displays, scratches caused by these foreign matter are now considered to be a problem.

[0019] Note that foreign matter with an average diameter of less than 10 μm is likely to be embedded in the glass sheet interleaf and therefore unlikely to cause scratches on the glass sheet. Furthermore, foreign matter with a particle strength C of less than 15 (MPa) is likely to be unlikely to cause scratches even if pressed into the glass sheet. Even if scratches are caused, their small size is likely to make them unlikely to cause disconnection or other defects. Therefore, it is important to control the amount of foreign matter contained in the interleaf so as to reduce the amount of foreign matter with an average diameter of 10 μm to 50 μm and a particle strength C of 15 (MPa) or more.

[0020] Foreign matter in interleaf paper is contained as impurities in the pulp used as the raw material for the interleaf paper, dust generated by the interleaf paper manufacturing equipment, and water used in the interleaf paper production process. These contaminants are mixed into the interleaf paper if they are not removed using filters or other methods. Furthermore, additives added in the process of producing interleaf paper other than glass plate interleaf paper remain in the pipes or on the surfaces of rolls that come into contact with the paper during paper feed, and adhere to the surface of the interleaf paper during the production of glass plate interleaf paper. Some of these contaminants may have a particle strength C of 15 MPa or more. Therefore, it is difficult to completely eliminate foreign matter with an average diameter of 10 μm to 50 μm and a particle strength C of 15 MPa or more.

[0021] Therefore, the inventors focused on the cushioning properties of slip sheets. The cushioning properties of slip sheets are defined by the compressive modulus K (MPa) in the thickness direction of the slip sheet. The smaller the value of the compressive modulus K (MPa), the higher the cushioning properties, and the larger the value, the lower the cushioning properties. After extensive research, the inventors found that slip sheets with higher cushioning properties can suppress scratches even when the slip sheet contains foreign matter with an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more.

[0022] This is thought to be because, when glass plates are stacked, the higher the cushioning properties of the slip sheet, the more easily foreign matter becomes embedded in the slip sheet, thereby reducing scratches caused by foreign matter with an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more.

[0023] (Raw pulp) The type of raw pulp is not particularly limited, but one having the properties required for interleaving paper is preferably used. Examples include chemical pulps such as kraft pulp (KP), sulfite pulp (SP), and soda pulp (AP); mechanical pulps such as groundwood pulp (GP), thermomechanical pulp (TMP), and chemithermomechanical pulp (CTMP); semi-chemical pulps such as chemiground pulp (CGP) and semi-chemical pulp (SCP) as intermediate mechanical-chemical pulps; non-wood fiber pulps made from kenaf, mitsumata, kozo, gampi, hemp, and the like; synthetic pulp, synthetic fiber, and recycled paper pulp (DIP). Pulp may be bleached or unbleached, and examples include bleached hardwood kraft pulp (LBKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), and unbleached softwood kraft pulp (NUKP). It may also contain carbon nanofibers (CNF). These raw pulps may be recycled paper pulp, virgin pulp, or a mixture of recycled paper pulp and virgin pulp. To particularly prevent contamination and scratches on glass plates due to particles and foreign matter, bleached LBKP or NBKP is particularly preferred, and pulp from which foreign matter has been removed using a cyclone cleaner or flotation device is even more preferred. "Foreign matter in pulp" refers to anything other than the fiber content in the pulp. Pulp may contain foreign matter such as compounds of SiC, ZrO2, Al2O3, TiO2, SiO2, Fe, Fe2O3, Cr, Ni, CaF2, MgO, CaCO3, Al, Cu, and their alloys, as well as aromatic polyether ketone (PEEK), polyphenylene sulfide (PPS), ultra-high molecular weight polyethylene (UPE), and resins such as epoxy. These are thought to be mixed in from minerals and equipment during the process from tree felling to pulp chip production.

[0024] (Method of manufacturing interleaving paper for glass plates) The method for producing interleaf paper for glass plates will be described with reference to the conceptual diagram of one embodiment of the method for producing interleaf paper for glass plates shown in FIG.

[0025] In the glass sheet interleaf paper manufacturing apparatus 100, raw material slurry for glass sheet interleaf paper (a slurry-like liquid obtained by diluting pulp with water and defibrating it) is beaten and then supplied in the form of a sheet from a head box 112 onto a lower wire 116 installed in a wire part 114. The raw material slurry supplied to the lower wire 116 is then sandwiched between the lower wire 116 and an upper wire 118, whereby it is spread to a uniform thickness and dewatered to become a wet web (paper).

[0026] The lower wire 116 and the upper wire 118 of the wire part 114 are permeable membranes formed in an endless band shape. Specifically, they are endless bands made of mesh made of plastic or metal material, or felt made of natural or synthetic fibers. The lower wire 116 and the upper wire 118 are wound around a plurality of rollers, and are moved in a circular motion at a predetermined speed by transmitting the driving force of a motor (not shown) to a driving roller among the plurality of rollers.

[0027] The wet paper web formed in the wire part 114 is transported to a press part 120 having a press roller, an endless belt-like felt, a pair of press rollers, etc., where further dewatering and pressing are carried out.

[0028] The wet paper that has passed through the press part 120 is transported to a dryer part 124 that is made up of a plurality of rollers, and is dried in an atmosphere of, for example, about 120° C. while passing through the dryer part 124 .

[0029] When passing through the dryer part 124, if the wet paper is transported at high speed as it is, there is a risk of the paper breaking, so the wet paper is transported with an auxiliary member called a canvas in contact with it.

[0030] The paper dried in the dryer part 124 is transported to the calender part 126, where a predetermined linear pressure is applied to the paper by sandwiching and transporting it between calender rolls, etc., to smooth the front and back surfaces. Various calendering methods, such as soft calenders, hard calenders, super calenders, and thermal calenders, can be used in the calendering process, and they can be used online or offline. A multi-stage nip may also be used. If necessary, a coater part may be provided between the dryer part 124 and the calender part 126, and a coating material or the like may be applied to the smoothed surface of the paper.

[0031] The paper that has been calendered in the calender part 126 is wound around a reel 128 as interleaf paper for glass plates, and is made into a roll (hereinafter referred to as a jumbo roll 130).

[0032] The glass plate interleaf paper made into the jumbo roll 130 is usually cut to a width according to the product, and wound up to make the interleaf paper roll 42 in which a long glass plate interleaf paper having a predetermined length of about 8000 m to 10000 m is wound.

[0033] The glass plate interleaf paper is fed from the jumbo roll 130, cut to a predetermined width (cut in the longitudinal direction) by a cutter 134, and wound up by a winder 136. When the glass plate interleaf paper fed from the jumbo roll 130 reaches a predetermined length, it is cut to the predetermined length (cut in the width direction) by the cutter 134, and an interleaf paper roll 42 is formed by winding a long glass plate interleaf paper of the predetermined width.

[0034] The long glass plate interleaf wound around the interleaf roll 42 is cut into cut sheets (rectangular shapes) of a size corresponding to the glass plates to be laminated, and is interposed between the glass plates to be laminated.

[0035] (thickness of interleaf paper) The thickness of the interleaf paper can be measured in accordance with the paper thickness measurement standard specified in JIS P8118: 2014. For the measurement, for example, an automatic elevating paper thickness meter (TM-600, manufactured by Kumagai Riki Kogyo Co., Ltd.) can be used.

[0036] Here, if the slip paper is too thin, even if the slip paper has high cushioning properties, foreign matter will not be embedded in the slip paper, making it more susceptible to scratches. Furthermore, the strength of the slip paper will be weakened, making it more susceptible to problems such as paper tears during slip paper production, resulting in reduced production efficiency. Therefore, the thickness of the glass plate slip paper of the present invention is 30 μm or more, preferably 40 μm or more, more preferably 50 μm or more, and even more preferably 60 μm or more. Furthermore, if the slip paper is too thick, the volume and weight of the slip paper will increase, reducing the number of glass plates that can be stacked on a pallet. Therefore, the thickness of the glass plate slip paper of the present invention is 150 μm or less, preferably 140 μm or less, more preferably 130 μm or less, and even more preferably 120 μm or less.

[0037] (Compression modulus) The glass plate interleaf paper of the present invention has a compressive modulus K (MPa) of 1.0 MPa or more and 8.5 MPa or less. The smaller the compressive modulus K, the higher the cushioning properties of the interleaf paper, and therefore the more effectively it can suppress scratches caused by foreign matter having an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 MPa or more. Here, the surface of the glass plate on which particle adhesion and scratches must be suppressed is particularly important. Therefore, the effects of the present invention can be achieved as long as the compressive modulus K (MPa) of the main surface of the interleaf that contacts the electronic circuit-forming surface and that comes into contact with the glass plate is within the above-mentioned range. The compressive modulus K (MPa) is more preferably 8.0 MPa or less, even more preferably 5.0 MPa or less, particularly preferably 3.0 MPa or less, and most preferably 2.0 MPa or less. The lower limit of the compressive modulus of the interleaf paper is 1.0 MPa or more. When the compressive modulus of the interleaf paper is equal to or greater than the above-mentioned lower limit, improved durability can be expected. In this specification, the compressive modulus K (MPa) of the glass plate interleaf paper is measured by the following method.

[0038] (Method for measuring compressive elastic modulus) The compressive modulus of the slip sheet can be measured, for example, using a constant pressure thickness measuring instrument (PG-02J, manufactured by TECLOCK). The thickness of the slip sheet when a load equivalent to pressure P1 (kPa) is applied to the approximate center of the slip sheet is defined as T1 (μm), and the thickness of the slip sheet when a load equivalent to pressure P2 (kPa) is applied to the approximate center of the slip sheet is defined as T2, and the (amount of strain) is calculated as (T1 - T2) / T1 (dimensionless). Then, the (compressive modulus) is calculated as (P2 - P1) / (amount of strain x 10 -3 ) (MPa). In this specification, P1 = 100 (kPa) and P2 = 270 (kPa).

[0039] The compressive modulus K of the slip sheet can be controlled mainly by the apparent density of the slip sheet and the density of the outermost layer. Apparent density is the density of the entire sheet. Normally, the thicker the paper, the greater the basis weight. However, the thinner the slip sheet, the lower the basis weight and the thicker the thickness, resulting in a lower density. This tends to result in a lower compressive modulus K, i.e., a higher cushioning effect. Methods for increasing the thickness of slip sheets at the same basis weight include increasing the content of softwood pulp, which has a high proportion of long fibers, adjusting the amount of beating to increase the freeness of the raw pulp, or adding a bulking agent. Note that it is desirable to add a small amount of bulking agents and other chemicals to prevent contamination of the glass plates.

[0040] The density of the outermost layer can be controlled by the pressure applied to the paper by the calender rolls in the calender part (hereinafter referred to as "nip pressure"). In other words, the smaller the nip pressure when the paper is nipped and transported in the calender part 126, the smaller the compressive modulus, resulting in a slip sheet with high cushioning properties. However, this operation tends to reduce adhesion between the fibers, which may lead to an increase in particles generated from the slip sheet. Therefore, it is preferable to lower the apparent density of the slip sheet while hardening the surface, resulting in an interleaf with overall cushioning properties. The compressive modulus K does not necessarily coincide with the apparent density. This is because it is affected by the density of the outermost layer. It can be assumed that the greater the density difference in the interleaf direction, the greater the deviation between the compressive modulus K and the apparent density.

[0041] In thermal calendering, high-smoothness paper can be obtained by increasing the thermoroll surface temperature and nip pressure, extending the contact time, and increasing the number of nip passes. On the other hand, increasing the nip pressure, contact time, and number of passes reduces bulk. Applying a temperature higher than the web temperature to the thermoroll increases the temperature gradient in the thickness direction of the web, promoting plastic deformation on the surface of the paper layer and making plastic deformation less likely inside the paper layer. Therefore, using a high-temperature thermoroll makes it easier to produce interleaving paper with high bulk and cushioning properties, and is therefore preferred for this invention. For the same reason, lowering the web temperature before calendering is even more preferred, as it increases the temperature gradient. Cooling methods include using air, water, and cooling rolls. Furthermore, if a small amount of water is applied to the paper web, and then immediately dried by blowing low-temperature dry air to remove the heat of evaporation and cool the paper web, the calendering process can be carried out afterwards, since the calendering process with a large temperature gradient can be carried out before the capillary penetration of water into the paper layers has completely occurred, thereby suppressing plastic deformation inside the paper layers and increasing bulk, which is particularly preferable. By limiting the time for which water is applied to the paper web to an extremely short period of time, the paper can be treated without causing roughening due to the destruction of inter-fiber bonds or deformation of the fibers.

[0042] It is also known that in a thermal soft calender, the degree of increase in smoothness differs between the paper on the metal thermo roll side and the paper on the resin elastic roll side. This type of treatment can particularly improve the smoothness of one surface, making it suitable for obtaining a slip sheet with a highly smooth surface and a low overall density. In one embodiment of the present invention, the temperature suitable for obtaining highly smooth paper is 25°C to 250°C. The higher the temperature, the greater the smoothing effect. However, temperatures above 250°C are likely to cause problems such as paper fading and uneven smoothing in the width direction, and also accelerate deterioration of the elastic roll. While smoothing is possible at temperatures below 100°C, the smoothing using the aforementioned temperature gradient becomes insufficient. Therefore, temperatures of 100°C or higher are desirable, particularly when obtaining slip sheets with a smoothness exceeding 100 seconds.

[0043] In one embodiment of the present invention, the nip pressure suitable for obtaining highly smooth paper is, for example, 5 kN / m to 350 kN / m. If the nip pressure is less than 5 kN / m, smoothing is insufficient, and if it exceeds 350 kN / m, the elastic roll is likely to deteriorate. In addition, as a method for achieving the same effect, papers with different densities may be combined to form the paper. By adjusting the type of calendering, the temperature during calendering, the nip pressure, and the like in this way, it is possible to obtain an interleaf paper having a high degree of surface smoothness and a small modulus of compressive elasticity.

[0044] (Smoothness) The glass plate interleaf paper of the present invention has a smoothness of at least one main surface of 20 seconds or more. The smoothness of the interleaf paper refers to irregularities on the surface of the interleaf paper with heights of several μm to several mm and irregularities of the fibers smaller than that, and high smoothness is achieved by bringing the fibers into close contact with each other.

[0045] This can be achieved by using pulp with short fiber lengths to eliminate gaps between fibers, by strengthening beating to make the fibers more intertwined, by reducing the surface roughness of the dryer cylinder in the drying process and increasing its cleanliness, by controlling the papermaking speed and the humidifying / dehumidifying environment to adjust the humidity while making paper, and by increasing the nip pressure during the calendering process.Higher smoothness means that the fibers and the fibers and foreign matter are in closer contact with each other, and this reduces the generation of particles such as paper dust and foreign matter from the paper surface. When the smoothness of the slip sheet is increased by calendering the slip sheet at a high nip pressure, the slip sheet is crushed, and the compressive modulus K tends to increase. However, if the smoothness of the slip sheet is less than 20 seconds, particles are more likely to be generated. Therefore, by adjusting not only the nip pressure but also the type of calendering and the temperature during calendering, as described above, it is possible to achieve a smoothness of 20 seconds or more while keeping the compressive modulus K between 1.0 MPa and 8.5 MPa, thereby achieving both particle suppression and scratch suppression.

[0046] Here, the surface of the glass plate on which contamination, i.e., particle adhesion, needs to be suppressed is the surface on which the electronic circuits are formed. Therefore, the effects of the present invention can be achieved if the main surface of the interleaf that comes into contact with the electronic circuit-forming surface has a smoothness of 20 seconds or more at the portion that comes into contact with the glass plate.

[0047] However, if the smoothness is too high, the adhesiveness of the slip sheet will increase, and static electricity will cause the slip sheet to stick to the glass plate or the transport roll. Therefore, for example, when removing the glass plate or slip sheet from the glass plate laminate (hereinafter also referred to as "unpacking"), problems such as the slip sheet sticking to the glass plate are likely to occur. Therefore, the smoothness of the slip sheet surface is preferably 400 seconds or less, more preferably 100 seconds or less, even more preferably 70 seconds or less, and particularly preferably 50 seconds or less. If the smoothness of the slip sheet surface is below the upper limit, problems such as the slip sheet sticking to the glass plate during unpacking can be reduced.

[0048] In this specification, the smoothness is measured by the measurement method described in the examples below. The location for measuring the smoothness is not particularly limited as long as it is measured at a location of the slip sheet that can come into contact with the glass plate, and for example, it is measured at approximately the center of the slip sheet.

[0049] (Sheet resistance (Ω / □)) As a result of extensive research, the inventors have found that there is a relationship between the adhesion of the slip sheet to the substrate and the electrostatic charge of the slip sheet. The electrostatic charge of the slip sheet can be expressed by the sheet resistance (surface resistivity) of the slip sheet. Sheet resistance is the resistance of a thin film such as paper or film to a surface area (1 cm2). 2) represents the resistance value per unit area. The higher the sheet resistance, the lower the conductivity and the easier it is to become charged. Sheet resistance is primarily affected by the moisture content of the slip sheet, but even with the same moisture content, the conductive properties vary depending on the state of the fibers (such as fiber density, entanglement, and orientation), the ingredients contained, and the thickness of the slip sheet, and the sheet resistance value can be controlled by combining these factors. The higher the moisture content and the denser the fibers, the lower the sheet resistance. In addition, to reduce sheet resistance, an antistatic agent can be added within a range that does not degrade the quality of the slip sheet. Sheet resistance can be measured, for example, using a Hirestar-UX MCP-HT800 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.).

[0050] In the glass plate interleaving paper of the present invention, the sheet resistance is 5.0 × 10 13 By keeping the sheet resistance of the interleaf paper at 5.0×10 Ω / □ or less, it is possible to reduce the occurrence of problems such as the interleaf paper sticking to the glass plate. 13 Ω / □ or less is preferable, and 2.5×10 13 Ω / □ or less is more preferable, and 1.0×10 13 If the sheet resistance of the slip sheet is equal to or less than the upper limit, it is possible to further reduce the occurrence of problems such as the slip sheet sticking to the glass plate when unpacking.

[0051] If the sheet resistance of the interleaf is too low, the interleaf and the glass plate may not adhere well together when the interleaf is packed onto a vertical pallet, resulting in problems such as the interleaf peeling off. Furthermore, if the water retention capacity of the interleaf is increased in an attempt to lower the sheet resistance of the interleaf, problems such as the interleaf and the glass plate sticking excessively to each other due to the moisture may occur. Therefore, the sheet resistance of the interleaf for glass plates of the present invention is set to 5.0 × 10 10 Ω / □ or more is preferable, and 7.5×10 10 It is more preferable that the resistance is Ω / □ or more, and 1.0×10 11 It is more preferable that the sheet resistance is Ω / □ or more. If the sheet resistance of the slip sheet is equal to or higher than the lower limit, it is possible to reduce the occurrence of problems such as the slip sheet peeling off or excessive sticking.

[0052] (Hard foreign matter resistance value) The hard foreign matter resistance value is a value obtained by multiplying the compressive elastic modulus K (MPa) and the number N (number / m) of foreign matter particles contained in the slip sheet that have an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more. 2 ) is defined as the product KN.

[0053] The smaller the hard foreign matter resistance value KN of an interleaf, the fewer foreign matter that can cause scratches and has an average diameter of 10 μm or more and a particle strength C of 15 (MPa) or more, or the smaller the compressive modulus K, which further reduces scratches on the glass plate. The hard foreign matter resistance value is preferably 35.0 or less, more preferably 30.0 or less, even more preferably 15.0 or less, particularly preferably 10.0 or less, and most preferably 5.0 or less. Attempting to reduce the hard foreign matter resistance value KN requires suppressing the inclusion of foreign matter during the manufacturing process, which increases manufacturing costs. Therefore, the lower limit of the hard foreign matter resistance value KN is preferably 0.1 or more, more preferably 0.5 or more.

[0054] (Foreign matter with an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more) In this specification, particle strength is used to evaluate foreign matter. A method for evaluating foreign matter in slip sheets other than particle strength is, for example, a method using Mohs hardness, as described in Japanese Patent Application Laid-Open No. 2016-006240. Mohs hardness defines hardness as "which side is scratched when one object is scratched with another object," and is generally used as a measure to compare the hardness of bulk minerals. Furthermore, because Mohs hardness is a relative value, even if two objects have the same Mohs hardness value, they do not necessarily have the same hardness (particle strength), and it is not possible to quantitatively express how easily one object is scratched; this cannot be determined without actually scratching the other object.

[0055] The results of an investigation conducted by the present inventors into the relationship between particle strength and Mohs hardness are shown in Fig. 1. Fig. 1 is a diagram showing the results of measuring the particle strength of multiple particles for minerals generally known for their Mohs hardness and various components that are thought to be minute foreign matter in slip sheets. Fig. 1 is a box plot showing the first, second, and third quartiles, maximum and minimum values, arithmetic mean values, and outliers. An outlier is data that is greater than the third quartile plus 1.5 times the interquartile range (the difference between the third and first quartiles), or less than the first quartile minus 1.5 times the interquartile range. The maximum value refers to the largest value among the data excluding outliers. The minimum value refers to the smallest value among the data excluding outliers. In the box plot in Figure 1, outliers are shown as white circles and the arithmetic mean is shown as a black circle. The inventors discovered that, as shown in Figure 1, the particle strength of minute foreign matter roughly corresponds to the Mohs hardness ranking, but does not necessarily coincide, and that there are cases where the Mohs hardness value and the particle strength value are reversed, and where there is a large variation in particle strength even among particles of the same type.

[0056] These defects are presumably caused by differences in the way each particle is generated, differences in density and crystallite orientation, the presence of voids, etc. Therefore, even if only foreign particles with a Mohs hardness of less than a certain level are present, scratches may occur on the glass plate due to the high particle strength of these foreign particles.

[0057] In such cases, even if it is not a problem with glass plates for conventional displays, it may become a problem with glass plates used in high-definition displays.From the above considerations, it is thought that it is more appropriate to express the hardness of minute foreign particles that scratch glass plates in terms of particle strength rather than a representative value on the Mohs hardness scale.

[0058] The average diameter of foreign matter refers to the arithmetic mean of the major and minor diameters of the external shape of foreign matter measured by observing the foreign matter present on the surface of the slip sheet from the thickness direction of the slip sheet. Foreign matter that can satisfy a particle strength C value of 15 MPa or more includes compounds such as SiC, ZrO2, Al2O3, TiO2, SiO2, Fe, Fe2O3, Cr, Ni, CaF2, MgO, CaCO3, Al, and Cu, as well as their alloys, and resins such as PEEK, PPS, UPE, and epoxy. However, because particle strength varies even for materials with the same composition, it is necessary to measure the particle strength of even the above foreign matter.

[0059] The number of foreign particles in the slip paper with an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more N (pieces / m 2 There are several ways to reduce the number of foreign matter N (pieces / m), including using pulp with a low content of foreign matter, removing magnetic materials with a magnetic filter, using centrifugal force to remove minute minerals and dust from pulp, and using a flotator to adsorb and remove foreign matter into fine bubbles. Furthermore, foreign matter contained in the raw water can be removed by filtration, or the papermaking process in the slip sheet manufacturing process can be carried out in a clean room to prevent the inclusion of dust, thereby reducing the number of foreign matter N (pieces / m). 2 ) can be reduced. Methods for using pulp with low foreign matter content include selecting pulp with low ash content or pulp with low levels of inorganic elements measured by fluorescent X-rays.

[0060] Number of foreign objects N (pieces / m 2 ) is preferably 10.0 or less, more preferably 5.0 or less, even more preferably 1.0 or less, particularly preferably 0.1 or less, and most preferably 0.01 or less. 2 ) is not particularly limited, but for example, it is 1.0 × 10 -6 Even if measures to prevent the inclusion of foreign matter as described above are taken, it is difficult to completely eliminate foreign matter having an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more.

[0061] Number of foreign objects N (pieces / m 2) can be measured using a micro-compression tester using the following method. For example, it is measured using a laser microscope (Keyence, VK-8500) and a micro-compression tester (Shimadzu, MCT-510). The interleaf paper is set on the stage, and 1600 areas, each with a field of view of 2 mm x 1.4 mm, are measured. At this time, the measurement can be performed automatically, using the microscope's teaching function to move one field of view for each measurement and measure the next field of view. Next, for each foreign particle in the measurement area, the size is calculated from the number of pixels, and particles with an average diameter of 10 μm or more and 50 μm or less are selected. These foreign particles are placed on the stage of the micro-compression tester, and the particle strength C is measured one by one. Particles with a particle strength C of 15 (MPa) or more are counted, and a 1m diameter is calculated from this number. 2 The number of foreign objects present per unit N (pieces / m 2 ) can be measured by converting it into

[0062] The particle strength C used here is not limited to that measured with a micro-compression tester, but may also be, for example, the particle hardness estimated from the indentation depth using a nanoindenter or the particle hardness measured with a micro-Vickers hardness tester.

[0063] (Arithmetic mean height Sa (μm)) The arithmetic mean height Sa is a parameter that expands the arithmetic mean height Ra of a line to a surface, and represents the average of the absolute values ​​of the difference between the average height of the slip sheet surface and the height of each point. The arithmetic mean height Sa is generally used to evaluate surface roughness.

[0064] When the arithmetic mean height Sa of the slip sheet is large, the smoothness of the slip sheet tends to be small. However, if the smoothness of the slip sheet is less than 20 seconds, particles are more likely to be generated. By ensuring that the arithmetic mean height Sa of the slip sheet is at a certain level or higher and that the smoothness is at least 20 seconds, it is possible to suppress both particles and scratches. Therefore, it is preferable that the smoothness of the slip sheet is 20 seconds or more, and that the arithmetic mean height Sa of at least one main surface of the slip sheet is 2.5 μm or more, and more preferably 3.0 μm or more. If the arithmetic mean height Sa of the slip sheet is above the lower limit, foreign matter present in the slip sheet is more likely to be embedded, and scratches caused by foreign matter being pressed can be expected to be reduced. The upper limit of the arithmetic mean height Sa of the slip sheet is preferably 8.0 μm or less, more preferably 6.0 μm or less, and even more preferably 4.0 μm or less. If the arithmetic mean height Sa is below the upper limit, particle generation can be reduced.

[0065] Here, the surface of the glass substrate on which particle adhesion and scratches are particularly required to be suppressed is the surface on which the electronic circuits are formed. Therefore, of the two main surfaces of the interleaf paper, the arithmetic mean height Sa of the main surface that comes into contact with the surface on which the electronic circuits are formed of the glass plate is particularly important.

[0066] The arithmetic mean height Sa is determined by obtaining height information for a total of 400 visual fields, each 2.0 mm × 1.4 mm in size and 20 × 20 visual fields at 10 mm intervals, in any region of the slip sheet, and calculating the average value of the arithmetic mean heights in each visual field. The arithmetic mean height Sa can be measured using a known measuring instrument, such as a laser microscope (Keyence, VK-8500).

[0067] (Maximum height Sz (μm)) The maximum height represents the distance from the highest point to the lowest point on the surface of the slip sheet. The maximum height Sz is calculated by obtaining height information from 20 × 20 fields of view at 10 mm intervals in a 2.0 mm × 1.4 mm area on the surface of the slip sheet, for a total of 400 fields of view, and then averaging the maximum heights in each field of view. The maximum height Sz can be measured using a known measuring device, such as a laser microscope (Keyence, VK-8500).

[0068] When the maximum height Sz of the slip sheet is large, the smoothness of the slip sheet tends to decrease. However, if the smoothness of the slip sheet is less than 20 seconds, particles are more likely to be generated. By ensuring that the maximum height Sz of the slip sheet is at a certain level or more and that the smoothness is at least 20 seconds, it is possible to suppress both particle generation and scratches. Therefore, it is preferable that the smoothness of the slip sheet is 20 seconds or more, and that the maximum height Sz of at least one main surface of the slip sheet is 45 μm or more, and more preferably 50 μm or more. If the maximum height Sz of the slip sheet is above the lower limit, foreign matter present in the slip sheet is more likely to be embedded, and scratches caused by foreign matter being pressed against the slip sheet surface can be expected to be reduced. Furthermore, the upper limit of the maximum height Sz of the slip sheet is preferably 80 μm or less, more preferably 65 μm or less, and even more preferably 54 μm or less. If the maximum height Sz is below the upper limit, particle generation can be reduced.

[0069] Here, the surface of the glass substrate on which particle adhesion and scratches are particularly required to be suppressed is the surface on which the electronic circuits are formed, and therefore, of the two main surfaces of the interleaf paper, the maximum height of the main surface that comes into contact with the surface of the glass plate on which the electronic circuits are formed is particularly important.

[0070] (Interleaf density) The density of the interleaf is determined by the basis weight (g / m 2 ) divided by the paper thickness (μm). The density of the interleaf paper is 0.4 (g / cm 3 ) or more is preferable, and 0.5 (g / cm 3 ) or more is more preferable, and 0.6 (g / cm 3 ) or more is more preferable, and 0.7 (g / cm 3 ) or more is particularly preferable. If the density of the slip paper is equal to or greater than the lower limit, the slip paper has sufficient strength, and defects such as paper breakage are less likely to occur during the manufacturing process. In addition, the density of the slip paper is preferably 1.6 (g / cm 3 ) or less is preferable, and 1.4 (g / cm 3 ) or less is more preferable, and 1.2 (g / cm 3 ) or less is more preferable, and 1.1 (g / cm 3 If the density of the slip sheet is equal to or less than the above upper limit, less raw material is required, resulting in high productivity.

[0071] (Glass plate laminate) The glass plate laminate of this embodiment includes at least two glass plates laminated together, with the glass plate interleaving paper of the present invention interposed between the glass plates.

[0072] (Glass plate packaging) The glass plate package of this embodiment includes a glass plate laminate in which at least two glass plates are stacked and the glass plate interleaving paper according to the present invention is disposed between the glass plates, and a pallet on which the glass plate laminate is placed.

[0073] Fig. 3 shows a cross-sectional view of an embodiment of a pallet on which glass plates are placed, and Fig. 4 shows a cross-sectional view of an embodiment of a glass plate package. The glass plate package 10 shown in Fig. 4 includes a glass plate laminate 12 and a pallet. The glass plate laminate 12 includes a glass plate 14 and an interleaving paper 16 for glass plates between the adjacent glass plates 14. The pallet 30 shown in Fig. 3 is a known pallet for packaging glass plates, and includes a base 22, an inclined platform 18 installed on the upper surface of the base, and a mounting platform 24. The angle θ between the mounting platform 24 and the inclined platform 18 is not particularly limited as long as the glass plates can be stably loaded, but 90° is preferred.

[0074] The angle γ of the inclined platform 18 is the angle between the inclined platform 18 and a horizontal plane. In other words, when the top surface of the base 22 on which the inclined platform 18 and the mounting platform 24 are installed is horizontal, as shown in Figure 3, the angle γ of the inclined platform 18 refers to the angle between the inclined platform 18 and the base 22. The closer the angle γ of the inclined platform 18 is to 90°, the more space is saved; however, the greater the pressure applied to the edge of the glass sheet, which may result in defects such as chipping. Furthermore, the closer the angle γ of the inclined platform 18 is to 0°, the more the pressure applied to the glass sheet is dispersed, preventing defects such as chipping on the edge; however, the greater the space required, which reduces storage and transportation efficiency. In this specification, pallets with an inclined platform angle of 10° or less are referred to as flat-stacked pallets, and pallets with an inclined platform angle of more than 10° are referred to as vertical-stacked pallets.

[0075] The pallet used may be a flat-stacked pallet or a vertical-stacked pallet, but in the case of large glass plates, the weight of the glass plate exerts a large pressure on the edges of the glass plate. Therefore, in the case of large glass plates, it is preferable to use a pallet on which the glass plate is placed in a flat-stacked state. Furthermore, since the larger the glass plate, the greater the pressure exerted on the edge surface of the glass plate, the angle of the inclined base is preferably 0° to 5°, more preferably 0° to 3°, and even more preferably 0° to 1°. However, when storing the glass plate in a truck or container for transporting the glass plate, a flat-stacked pallet may not be able to be used. Therefore, a vertical-stacked pallet may be used to save space.

[0076] A large glass plate refers to, for example, a glass plate having at least one side of 2400 mm or more, specifically, a glass plate having a long side of 2400 mm or more and a short side of 2000 mm or more. The large glass plate is preferably a glass plate having at least one side of 2400 mm or more, for example, a glass plate having a long side of 2400 mm or more and a short side of 2100 mm or more, more preferably a glass plate having at least one side of 3000 mm or more, for example, a glass plate having a long side of 3000 mm or more and a short side of 2800 mm or more, more preferably a glass plate having at least one side of 3200 mm or more, for example, a glass plate having a long side of 3200 mm or more and a short side of 2900 mm or more, and particularly preferably a glass plate having at least one side of 3300 mm or more, for example, a glass plate having a long side of 3300 mm or more and a short side of 2950 mm or more.

[0077] The thickness of the glass plate is preferably 1.30 mm or less. By making the glass plate thinner, the weight per plate becomes lighter, allowing for an increase in the number of plates that can be loaded and for a reduction in the etching time during the production of liquid crystal panels. The thickness of the glass plate of the present invention is more preferably 0.75 mm or less, even more preferably 0.65 mm or less, and most preferably 0.55 mm or less. The thickness can also be 0.10 mm or less, or 0.05 mm or less. However, from the viewpoint of preventing deflection due to its own weight, the thickness is preferably 0.10 mm or more, more preferably 0.20 mm or more.

[0078] The glass plate is preferably used in the manufacture of displays. Since there are few particles, such as paper dust and foreign matter, present on the main surfaces of the glass plate, and there are few scratches on the surface of the glass plate, the occurrence of defects such as disconnections can be suppressed. The display is preferably used as a substrate for a liquid crystal display or an organic EL display. Furthermore, since the glass plate interleaf paper according to the present invention can suppress scratches on the glass plate, its effect is remarkable when used in a high-definition display. Therefore, the glass plate for a display using the glass plate interleaf paper according to the present invention preferably has a pixel count of 2K (1920 × 1080) or more, more preferably 4K (3840 × 2160) or more, and even more preferably 8K (7680 × 4320) or more.

[0079] The glass plate interleaf paper, glass plate laminate, and glass plate package have been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications may be made within the scope of the gist of the present invention. [Example]

[0080] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. In the following, Examples 1 to 10 are examples, and Examples 11 to 13 are comparative examples. Unless otherwise specified, the manufactured slip sheets were subjected to humidity conditioning treatment under standard conditions in accordance with JIS P8111:1998, and then measurements were made. Each measurement of the slip sheets was made before they were used as glass plate laminates.

[0081] Smoothness was measured in accordance with JIS P8119:1998 Smoothness Testing Method (Beck Method) and JIS P8155:2010 Smoothness Testing Method (Oken Method). It is generally known that the Oken Method produces higher smoothness than the Beck Method. However, the measurement time for the Beck Method increases with increasing smoothness. Therefore, when the measurement time exceeded 100 seconds, the smoothness was measured using the Oken Method and converted to a Beck Method value. The smoothness values ​​for Examples 2, 4, 6, 8, 9, 12, and 13 were measured using the Oken Method and converted to a Beck Method value. The smoothness of the slip sheets produced in Examples 1 to 13 was measured at approximately the center of the first and second main surfaces of the slip sheets according to the above-mentioned method, and the higher value was taken as the smoothness of the slip sheet. Next, the arithmetic mean height Sa and maximum height Sz of the smoother main surface were measured using a laser microscope (Keyence, VK-8500). The arithmetic mean height Sa and the maximum height Sz were each measured at approximately the center of the main surface.

[0082] Sheet resistance was measured using a Hirestar-UX and a URS probe (MCP-HTP14). To ensure the probe remained upright during measurements, a concentric cylindrical load of 600 g was attached to the outer periphery of the probe, and the load was positioned far enough away from the sample to avoid interfering with the measurement. Following the MCC-A method (measurement of the Teflon (registered trademark) side), the sample was placed on a 0.5 mm thick glass plate as an insulator on the non-measurement side of the sample. The probe was placed approximately in the center of the measurement surface, and a voltage of 1000 V was applied. The measured value was the value measured 10 seconds later. For this measurement, the slip sheet was left to stand for 15 minutes at 23°C and 50% humidity. This was intended to simulate the conditions experienced when the slip sheet is actually unwound from the roll surface and loaded onto a glass substrate. The measurement surface was the smoother of the first and second main surfaces of the slip sheet.

[0083] Next, a constant pressure thickness tester was used to measure the compressive elastic modulus of the interleaf paper. Next, a laser microscope and a micro-compression tester were used to measure 1600 areas of 2.0 mm x 1.4 mm, and the number of foreign particles (pieces) present in the 1600 areas, with an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more, was counted.2 The number of foreign objects present per unit N (pieces / m 2 ) was converted.

[0084] The glass plate interleaving papers produced in Examples 1 to 13 were molded into a size of 500 mm x 400 mm, each with a thickness of 0.5 mm, and interposed between glass plates measuring 470 mm x 370 mm to form a glass plate laminate consisting of 180 glass plates. The interleaving papers were arranged so that each side had a protrusion of 15 mm. The glass plates were produced by the float process, with their bottom surfaces polished with cerium oxide. Both surfaces of the polished glass plates were then washed with alkali and dried with clean dry air. The bottom surface refers to the main surface of the glass plate produced by the float process that had been in contact with molten tin. The glass plates were laminated such that the smoother of the first or second main surface of the interleaving paper was in contact with the bottom surface of the polished glass plate. The forming method for the glass plates used in the present invention is not limited to the float process; it may also be a downdraw method, a roll-out method, or an unpolished glass plate.

[0085] Each glass plate stack was placed flat on a pallet (180 glass plates) to create a glass plate package. The pallet was made of aluminum and did not have any vibration-absorbing materials such as rubber or springs, nor any mechanism to suppress vertical movement of the stack. The glass plate package thus created was subjected to a random vibration test in accordance with JIS Z0232:2004 using a vibration testing machine (IMV, m120 / MA1) in the vertical direction for one hour. The vibration conditions were as follows: an acceleration power spectral density of 5.92 (m / s), which simulates a general transportation environment (mainly roads), as specified in Annex Table A.1 of the same regulation. 2 The environmental temperature was 25±2°C and humidity was 50±5%.

[0086] After the vibration test, the glass plates located above the third glass plate from the bottom of the glass plate package were removed and cleaned, and then the amount of particles adhering to the bottom surface of the glass plate and scratches were measured and evaluated using a foreign matter inspection machine.

[0087] <Measurement and evaluation of particle adhesion and scratches on glass plate surfaces> The bottom surface of the glass plate removed from the package was passed through a spray shower cleaner consisting of two rows of shower pipes with uniform fan-shaped nozzles, through which pure water (ion-exchanged water) flowed at a piping pressure of 1 MPa and a flow rate of 20 L / min, at a speed of 3 m / min. The glass plate was then dried with an air knife spraying clean dry air to obtain a cleaned substrate. The cleaned substrate was measured using an FPD foreign matter inspection machine (Toray Engineering Co., Ltd., HS-830e) in Normal (1.0 μm) mode to obtain a particle count. At least three substrates were measured for each test condition, and the average was used to calculate the particle count for each test condition. Note that particles in the foreign matter inspection machine generally include not only convex deposits but also concave defects. However, in this specification, convex deposits are referred to as particles, and concave defects are referred to as defects.

[0088] The particle adhesion was measured using an FPD foreign matter inspection device before and after the laminate was produced and evaluated using the difference in the number of particles. The evaluation criteria were as follows: A: The difference in particle count is 20,000 particles / m 2 is less than. B: The difference in particle count is 20,000 particles / m 2 More than 50000 pieces / m 2 is less than. C: The difference in particle count is 50,000 particles / m 2 That's all.

[0089] The scratching property of the glass plate was observed using an FPD foreign matter inspection device and evaluated according to the following evaluation criteria. A: The number of scratches on the bottom surface of the glass plate is 0.5 / m 2 is less than. B: The number of scratches on the bottom surface of the glass plate is 0.5 / m 2 More than 3.0 pieces / m 2 is less than. C: The number of scratches on the bottom surface of the glass plate is 3.0 / m 2 More than 10.0 pieces / m 2is less than. D: The number of scratches on the bottom surface of the glass plate is 10.0 / m 2 That's all.

[0090] (Measurement of compressive elastic modulus K (MPa)) A constant pressure thickness measuring device (TECLOCK, PG-02J) equipped with a load mounting section so that the load could be set arbitrarily was used, with no other modifications. The minimum thickness reading was 1 μm. First, with an indenter diameter of 5 mm, the paper thickness when a load equivalent to a pressure P1 (kPa) was applied to approximately the center of the slip sheet was defined as T1 (μm), and the paper thickness when a load equivalent to a pressure P2 (kPa) was applied to approximately the center of the slip sheet was defined as T2, and the (strain amount) = (T1 - T2) / T1 (dimensionless) was calculated. Next, the (compressive elastic modulus K) = (P2 - P1) / (strain amount x 10 -3 ) (MPa) was calculated. Here, P1 = 100 (kPa) and P2 = 270 (kPa). The compressive modulus was measured by pressing an indenter against the surface with greater smoothness, either the first or second main surface of the slip sheet.

[0091] (Number of foreign particles N (pieces / m) with an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more 2 ) measurement) The slip sheet was placed on the stage of a laser microscope (Keyence, VK-8500), and the edges were taped to prevent it from lifting. Approximately in the center of the slip sheet, 1600 areas measuring 2.0 mm x 1.4 mm were measured. The size was calculated from the number of pixels, and particles with an average diameter of 10 μm to 50 μm were selected. Measurements can also be performed automatically, using the microscope's teaching function to move one field of view for each measurement and measure the next field of view. The particles were then placed on the stage of a microcompression tester (Shimadzu, MCT-510). The microcompression tester used had a 50 μm diameter diamond flat indenter, a test force resolution of 5 μN, and a displacement resolution of 0.01 μm. The particle's external shape was confirmed using the microscope attached to the tester, and the major and minor diameters were measured to calculate the average diameter by arithmetic mean. A test force of 20 mN was applied to the particles at a loading speed of 0.44 mN / sec, and the point at which the average diameter after compression became 10% smaller than the average diameter before compression was defined as the 10% compression point. Using this test force, the formula known as the general formula for calculating particle fracture strength was used: Cx = 2.48 × (test force at 10% compression point) / (average particle diameter). 2 Cx was calculated using the above formula, and the calculated Cx was taken as the particle strength C. Then, particles with a particle strength C of 15 (MPa) or more were counted, and the number of foreign particles N (number / m 2 ) was calculated.

[0092] Generally, a test force of more than 15 MPa is applied, and the point at which the particle breaks (the point at which the test force remains almost constant and only the displacement changes significantly due to the particle breaking and the indenter being pressed in suddenly) is taken as the breaking point. Using the test force at this point, Cs = 2.48 × (test force at breaking point) / (average particle size) 2 is calculated, and the calculated Cs is often used as the particle strength C.

[0093] However, for particles where Cx calculated using the test force at the 10% compression point is around 15 (MPa), the particle breaking point is not detected, and therefore in this specification Cx is calculated using the test force at the 10% compression point, and this value is used as the particle strength C. Furthermore, if the particle breaking point is observed before the 10% compression point is reached, it is clear that the particle shape has changed significantly at that point, and in this case the value of Cs is used as the particle strength.

[0094] (Example 1) A pulp slurry containing 100% NBKP was beaten using a double-disc refiner, and then the raw material slurry was sprayed onto a Fourdrinier former at a stock concentration of 1% to obtain the basis weight shown in Table 1. After forming a paper layer, it was dried through a multi-cylinder dryer. The raw material water used was pure water treated with a 40 μm filter. The paper was then processed in a hot soft calender at a temperature of 100°C and a nip pressure of 10 (kN / m). The resulting laminated paper had a basis weight of 45.1 g / m. 2 , thickness 80 μm, density 0.53 (g / cm 3 ), the smoothness of the first main surface was 25 seconds, and the smoothness of the second main surface was 23 seconds.

[0095] (Example 2) An interleaf paper was obtained in the same manner as in Example 1, except that the temperature gradient was applied at 150° C. in the thermal soft calendering treatment, and the nip pressure was 120 (kN / m) and the treatment was performed with a thermal gradient.

[0096] (Example 3) An interleaf paper was obtained in the same manner as in Example 1, except that the raw material composition was 50% NBKP and 50% LBKP (A) shown in Example 1, a water filter with an opening diameter of 20 μm was used, and a hard calender was used in the calendering process at a nip pressure of 30 (kN / m).

[0097] (Example 4) An interleaf paper was obtained in the same manner as in Example 1, except that the raw material system consisting of pulp and water shown in Example 3 was used and the calendering was carried out at a temperature of 150°C and a nip pressure of 150 (kN / m).

[0098] (Example 5) An interleaf paper was obtained in the same manner as in Example 3, except that a water filter with an opening diameter of 5 μm was used and the treatment was carried out at a nip pressure of 50 (kN / m).

[0099] (Example 6) An interleaf paper was obtained in the same manner as in Example 1, except that a raw material system consisting of pulp and water shown in Example 5 was used, and the material was cooled using water and low-temperature air blowing before calendering, and then calendered at a temperature of 200°C and a nip pressure of 170 (kN / m).

[0100] (Example 7) After papermaking, the raw material slurry was dried in a Yankee dryer, and an interleaf paper was obtained in the same manner as in Example 1, except that no calendering treatment was carried out.

[0101] (Example 8) Interleaf paper was obtained in the same manner as in Example 4, except that the raw material composition was 50% NBKP and 50% LBKP (B) shown in Example 1, and a water filter with an opening diameter of 40 μm was used. LBKP (A) and LBKP (B) are hardwood bleached kraft pulps derived from wood from different regions.

[0102] (Example 9) An interleaf was obtained in the same manner as in Example 6, except that the machine speed was slowed by 20% and a 150°C dryer roll was provided before winding the interleaf to carry out a drying treatment and reduce the moisture content.

[0103] (Example 10) An interleaf was obtained in the same manner as in Example 1, except that the interleaf was subjected to a humidifying treatment before being wound up, and the moisture content was increased.

[0104] (Example 11) An interleaf paper was obtained in the same manner as in Example 1, except that after the raw material slurry was made into paper, calendering was not carried out.

[0105] (Example 12) Using the raw material system consisting of pulp and water shown in Example 8, a raw material slurry was beaten to a freeness of 200 mL CSF, and paper was made from the raw material slurry. After that, a wet paper was made using a moisture-adding device, and then the wet paper was subjected to 10-stage supercalendering treatment under conditions of a temperature of 150°C and a nip pressure of 200 kN / m, to obtain a glassine slip paper.

[0106] (Example 13) An interleaf paper was obtained in the same manner as in Example 1, except that the raw material system consisting of pulp and water shown in Example 3 was used, the machine speed was slowed by 20%, and the calendering was performed at a temperature of 100°C and a nip pressure of 350 kN / m.

[0107] [Table 1]

[0108] <Result> Table 1 shows the measurement results and evaluation results. According to Table 1, when the smoothness was 20 seconds or more, the particle adhesion was rated A or B for all samples. On the other hand, when the smoothness was less than 20 seconds, the particle adhesion amount was rated C for all samples. Furthermore, when the compressive elastic modulus K was 8.5 MPa or less, the scratch resistance was rated A or B for all samples. On the other hand, when the compressive elastic modulus K was more than 8.5 MPa, the scratch resistance was rated C or D.

[0109] This application is based on Japanese Patent Application No. 2020-195392 filed on November 25, 2020, the contents of which are incorporated herein by reference. [Explanation of symbols]

[0110] 10...Glass plate package 12...Glass plate laminate 14...Glass plate 16...Glass plate interleaving paper 18...Slope 22...Foundation 24...Placement table 30...pallet 42...Interleaf roll 100...Glass plate interleaf manufacturing device 112...Headbox 114...Wire part 116...Lower wire 118...Upper wire 120...Press Section 124...Dryer part 126...Calendar part 128...reel 130...Jumbo roll 134...Cutter 136...Winder

Claims

1. A glass plate interleaf having a thickness of 30 μm or more and 150 μm or less, The smoothness of at least one main surface of the glass plate interleaf paper is 20 seconds or more, The compressive elastic modulus K measured on the main surface is 1.0 MPa or more and 8.5 MPa or less, The glass plate interleaf has a hard foreign matter resistance value KN of 35.0 or less, which is the product of the compressive elastic modulus K (MPa) and the number N (pieces / m2) of foreign matter contained in the glass plate interleaf and having an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more.

2. The glass plate interleaving paper according to claim 1 , wherein the arithmetic mean height Sa of the main surfaces is 2.5 μm or more.

3. The glass plate interleaving paper according to claim 1 or 2, wherein the maximum height Sz of the main surfaces is 45 μm or more.

4. The density of the glass plate interleaf paper is 0.4 (g / cm ３ ) or more 1.6 (g / cm ３ ) or less, The glass plate interleaving paper according to any one of claims 1 to 3, wherein the smoothness of the main surface is 20 seconds or more and 400 seconds or less.

5. The sheet resistance of the glass plate interleaf paper is 5.0 × 10 １０ (Ω / □) or more 5.0×10 １３ The glass plate interleaving paper according to any one of claims 1 to 4, wherein the interleaving paper has a hardness of 0.05% or less (Ω / □).

6. The compressive elastic modulus K (MPa) and the number N (number / m) of foreign particles having an average diameter of 10 μm or more and 50 μm or less and a particle strength C of 15 (MPa) or more contained in the glass plate interleaf paper ２ 6. The glass plate interleaving paper according to claim 1, wherein a hard foreign matter resistance value KN, which is the product of KN and KN, is 15.0 or less.

7. The glass plate interleaving paper according to any one of claims 1 to 6, wherein the main surface is a surface that contacts a surface of the glass plate on which an electronic circuit is formed.

8. A glass plate laminate in which at least two or more glass plates are laminated, wherein the glass plate laminate has the glass plate interleaving paper according to any one of claims 1 to 7 between the glass plates.

9. A glass plate package comprising the glass plate laminate according to claim 8 and a pallet on which the glass plate laminate is placed.

Images