JP7596979B2 - Glass plate interleaving paper - Google Patents

Description

The present invention relates to glass plate interleaving paper, glass plate laminates, and glass plate packages.

Glass plates used in flat panel displays (FPDs) such as liquid crystal displays have fine electronic wiring (hereafter also referred to as "wiring") formed on the surface of the glass plate, so even the slightest scratches or dirt on the surface can cause defects such as broken wiring. For this reason, a high level of cleanliness is required for the surface of the glass plate.

Glass plates are transported stacked together to increase transport efficiency. At this time, glass plate interleaving paper (hereinafter simply referred to as "interleaving paper") is placed between adjacent glass plates to prevent scratches on the glass plate surface during transport.

However, foreign matter may become mixed in during the process of manufacturing the interleaf paper, or may adhere to the surface of the glass plate from the interleaf paper due to the influence of various chemical substances. Most of the foreign matter that adheres to the surface of the glass plate is removed by cleaning before the process of forming wiring on the surface of the glass plate, but it may remain on the surface of the glass plate even after cleaning and may cause disconnection or other problems. For this reason, there is a demand for interleaf paper for glass plates that reduces the amount of foreign matter that adheres to the surface of the glass plate.

Patent Document 1 attempts to reduce contamination of the glass plate surface by lowering the concentrations of aluminum, silicon, magnesium, etc. contained in the glass plate interleaf paper.

Patent Publication 2017-210286

However, as displays have become more highly detailed in recent years, the width and pitch of the wiring formed on the surface of the glass plate have become thinner than before, which has led to problems such as wire breakage during wiring formation, even when using glass plate interleaving paper such as that described in Patent Document 1.

The inventors investigated the above problem and found that it was caused by microscopic silica particles that remained on the surface of the glass plate even after cleaning. Since it is difficult to remove microscopic silica particles in the cleaning process before forming the wiring, it is important to prevent microscopic silica particles from adhering to the surface of the glass plate.

The present invention aims to provide an interleaving paper for glass plates that prevents the adhesion of minute silica foreign matter to the surface of the glass plate, thereby preventing defects such as breaks during wiring formation.

The glass plate interleaf paper according to the present invention is characterized in that ^, when a silicon concentration measured by X-ray fluorescence analysis is X and a calcium concentration measured by Y are X and Y, respectively, X is 200 ppm or ^less , and an X/Y ratio, which is a value obtained by dividing the silicon concentration by the calcium concentration, is 4.00 or less.

The glass plate interleaving paper preferably has an X/Z ratio, which is the value obtained by dividing the silicon concentration by the magnesium concentration, of 3.00 or less, where Z is the magnesium concentration measured by X-ray fluorescence analysis.

It is preferable that Z is 20 ppm or more and 100 ppm or less.

It is preferable that Y is 20 ppm or more and 400 ppm or less.

It is preferable that the number of silicon-containing foreign matter having a size of 0.5 μm or more and 50 μm or less present on at least one surface of the glass plate interleaf paper is 2000 pieces/mm2 ^{or less} .

It is preferable that the number of silicon-containing foreign matter having a size of 1 μm or more and 10 μm or less present on at least one surface of the glass plate interleaf paper is 1000 pieces/mm2 ^{or less} .

It is preferable that the number of silica foreign particles having a size of 0.5 μm or more and 50 μm or less present on at least one surface of the glass plate interleaf paper is 100 pieces/mm2 ^{or less} .

The glass plate interleaving paper is preferably such that the number of silica foreign particles having a size of 1 μm or more and 10 μm or less present on at least one surface of the interleaving paper is 50 pieces/mm2 or ^less .

It is preferable that the air resistance of the glass plate interleaving paper is 5 seconds or more.

The glass plate laminate of the present invention is formed by laminating at least two glass plates and has the glass plate interleaving paper of the present invention between adjacent glass plates.

The glass plate package of the present invention comprises the glass plate laminate and a pallet on which the glass plate laminate is placed.

It is possible to provide interleaving paper for glass plates that prevents minute silica particles from adhering to the surface of the glass plate. This makes it possible to prevent defects such as breaks in wiring when it is formed.

FIG. 2 is a conceptual diagram showing a method for producing glass plate interleaf paper. FIG. 2 is a conceptual diagram showing a pallet on which a glass plate is placed. FIG. 1 is a conceptual diagram showing one embodiment of a glass plate package.

The following describes preferred embodiments of the glass plate interleaving paper according to the present invention. The embodiments described below are merely examples, and the present invention should not be interpreted as being limited to these embodiments.

From the viewpoint of transport efficiency, glass plates are transported by stacking at least two or more glass plates and placing them on a pallet. A glass plate laminate is made by stacking at least two or more glass plates with interleaving paper between adjacent glass plates, and a glass plate laminate placed on a pallet is called a glass plate package. When glass plates in a glass plate laminate come into contact with each other, scratches may occur on the surfaces of the glass plates. Such scratches are known to cause problems such as broken wires in the manufacturing process of displays and the like. Therefore, by placing glass plate interleaving paper between the glass plates, scratches on the surfaces of the glass plates are suppressed.

However, foreign matter contained in the glass plate interleaf paper may adhere to the surface of the glass plate, causing problems such as wire breakage. In particular, with the increasing high definition of displays in recent years, problems such as wire breakage have begun to occur even when using glass plate interleaf paper, which was not a problem in the past.

The inventors therefore analyzed the foreign matter adhering to the glass plate. As a result, they found that a large amount of silicon-containing foreign matter was adhering to the surface of the glass plate. They also found that among the silicon-containing foreign matter, minute-sized silica foreign matter is particularly difficult to remove by cleaning before wiring formation, and remains after cleaning, causing problems. In this specification, minute-sized silica foreign matter refers to silica foreign matter with a maximum diameter of 10 μm or less.

In addition, silica foreign particles with a maximum diameter of more than 10 μm are easy to remove by cleaning performed before forming wiring on the glass plate, and are therefore less likely to cause defects such as broken wires than silica foreign particles with a maximum diameter of 10 μm or less.

Among silicon-containing foreign matter, microscopic silica foreign matter is particularly difficult to remove by cleaning and tends to remain even after cleaning. This is thought to be because silicon-containing foreign matter other than silica foreign matter such as talc is often spherical, whereas silica foreign matter is often flat in shape. In other words, when it is flat in shape, it has a low height and is therefore difficult to remove in cleaning processes such as brush cleaning, and is therefore likely to remain.

The inventors also discovered that the silica foreign matter remaining on the surface of the glass plate is a foreign matter that has adhered to the surface of the glass plate from the interleaf paper. For these reasons, it is important to reduce the amount of minute silica foreign matter present in the interleaf paper for glass plates.

(Method of manufacturing interleaving paper for glass plates)
A liquid stock for glass sheet interleaf paper (a liquid obtained by diluting pulp with water) is supplied in the form of a sheet from a head box 112 onto a lower wire 116 installed in a wire part 114. The liquid stock supplied to the lower wire 116 is then sandwiched between the lower wire 116 and the upper wire 118, whereby the liquid stock is spread to a uniform thickness and dehydrated to become a wet paper (paper).

The lower wire 116 and the upper wire 118 of the wire part 114 are permeable membranes formed in an endless strip shape. Specifically, they are endless strips made of a net made of plastic or metal material, or felt made of natural or synthetic fibers.

The lower wire 116 and the upper wire 118 are hung over multiple rollers and rotated at a predetermined speed by transmitting the driving force of a motor (not shown) to a drive roller among the rollers.

The wet paper formed in the wire part 114 is transported to the press part 120, which has a press roller, an endless felt strip, and a pair of press rollers, where further dewatering and pressing are performed.

After passing through the press part 120, the wet paper is transported to the dryer part 124, which is made up of multiple rollers, and is dried while passing through the dryer part 124, for example, in an atmosphere of about 120°C.

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

The paper dried in the dryer part 124 may be transported to the calendar part 126, where it may be subjected to a calendaring process such as by being sandwiched and transported by calendar rolls, to smooth the front and back surfaces. If necessary, a coater part may be provided between the dryer part 124 and the calendar part 126, and paint or the like may be applied to the smoothed surface of the paper.

The paper that has been calendered in the calender part 126 is wound onto a reel 128 as interleaving paper for glass plates and made into a roll (hereafter referred to as a jumbo roll 130).

The glass sheet interleaf paper made into the jumbo roll 130 is usually cut to a width according to the product, and wound up to become an interleaf paper roll 42 with a predetermined length of glass sheet interleaf paper of about 8,000 to 10,000 m.

The glass plate interleaf paper is sent out from the jumbo roll 130, cut to a specified width (cut in the longitudinal direction) by the cutter 134, and wound up by the winder 136. When the glass plate interleaf paper sent out from the jumbo roll 130 reaches a specified length, it is cut to the specified length (cut in the width direction) by the cutter 134, and the interleaf paper roll 42 is made by winding up a long glass plate interleaf paper of the specified width.

The long glass plate interleaving paper wound on the interleaving paper roll 42 is cut into cut sheets (rectangular) of a size appropriate for the glass plates to be stacked, and is interposed between the glass plates to be stacked.

(Silicon concentration)
The silicon contained in glass plate interleaving paper is mainly derived from the raw materials cellulose pulp and water, and from dust in the air that gets mixed in during the manufacturing process. Silicon is present in the manufactured glass plate interleaving paper mainly as silicon-containing foreign matter such as hydrated magnesium silicate (hereinafter also referred to as "talc") and silica.

The glass plate interleaving paper of the present invention has a silicon concentration of 200 ppm or less as measured by fluorescent X-ray analysis, which sufficiently reduces the amount of silica foreign matter in the glass plate interleaving paper and suppresses the occurrence of defects such as breaks.

The silicon concentration is preferably 150 ppm or less, more preferably 130 ppm or less, even more preferably 100 ppm or less, and particularly preferably 50 ppm or less.

In this specification, the silicon concentration of the glass sheet interleaf paper measured by X-ray fluorescence analysis is also referred to as X. X is measured by the following method.

(Method of measuring silicon concentration X)
The X-ray fluorescence analysis in the present invention can be carried out using a commercially available X-ray fluorescence analyzer such as ZXS PRIMUS (Rigaku Corporation). As a pretreatment for the X-ray fluorescence analysis, the glass plate interleaf paper is cut in advance to a size suitable for measurement using a blade or the like. The cut paper is placed on a sample stage. In this case, a sample stage with a known composition and high purity may be used so that the components of the sample stage do not become noise in the measurement, or a deep-bottomed cup-shaped sample stage may be used, or the glass plate interleaf paper may be stacked. Next, the glass plate interleaf paper is fixed in place in the measurement area using a lid with holes. The sample stage is placed in an X-ray fluorescence analyzer, and after the inside of the apparatus is evacuated, X-rays are irradiated onto the measurement surface, and the fluorescent X-rays generated from the glass plate interleaf paper are measured and analyzed.

The larger the evaluation area, the more stable the results, so the evaluation area is preferably 10 square millimeters or more, more preferably 100 square millimeters or more, and even more preferably 600 square millimeters or more. Unless otherwise specified in this specification, the evaluation area is 700 square millimeters.

To quantify the detected elements, a reference sample with a known concentration was measured in advance, and the numerical values of each element were corrected from the X-ray intensity. The power used for the measurement was 3000 W.

The measurements quantified the content of the elements sodium, magnesium, aluminum, silicon, phosphorus, sulfur, chlorine, potassium, calcium, iron, nickel, copper, and zircon.

If the silicon concentration is too low, the bubbles will not break easily when the glass sheet interleaf raw material liquid is stirred, and holes may appear in the glass sheet interleaf. Therefore, the silicon concentration is preferably 10 ppm or more, more preferably 15 ppm or more, and even more preferably 20 ppm or more.

The silicon concentration is affected by the raw material cellulose pulp, the raw material water, and the manufacturing method of the paper-making process.

The silicon concentration can be reduced by selecting raw cellulose pulp that does not contain silicone oil or that contains only a small amount of silicone oil, that does not contain talc as a pitch control agent, or that has been subjected to strong centrifugal force to remove tiny minerals and dirt. The silicon concentration can also be reduced by using groundwater or river water as raw water from which silicon components derived from minerals have been removed by sufficient filtration. In addition, in the manufacturing method of interleaf paper, the silicon concentration can be reduced by performing the papermaking process in a clean room to prevent the intrusion of dirt and dirt, or by separating the papermaking process using cellulose pulp containing silicone oil from the papermaking process for glass plate interleaf paper.

The cellulose pulp may be any of a variety of glass plate interleaving papers made from various raw materials, including chemical pulps such as kraft pulp (KP), sulfite pulp (SP), and soda pulp (AP); semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP); mechanical pulps such as groundwood pulp (GP), thermomechanical pulp (TMP, BCTMP), and refiner ground wood pulp (RGP); non-wood fiber pulps made from paper mulberry, mitsumata, hemp, kenaf, and the like; and synthetic pulps. Mixtures of these may also be used.

(Calcium concentration)
The calcium contained in the glass sheet interleaving paper is mainly derived from the raw materials cellulose pulp and water, and from dust in the air that gets mixed in during the manufacturing process. Calcium is present in the manufactured glass sheet interleaving paper as silicon-containing foreign matter such as calcium metasilicate and calcium orthosilicate, or as calcium carbonate.

In this specification, the calcium concentration of the glass sheet interleaf paper measured by X-ray fluorescence analysis is also referred to as Y. Y is measured using the same procedure as described above (Method of measuring silicon concentration X).

The smaller the X/Y ratio, which is the silicon concentration divided by the calcium concentration, the more calcium is present relative to silicon. In addition to existing as calcium carbonate, calcium also exists as compounds containing silicon, such as calcium metasilicate and calcium orthosilicate. Therefore, it is believed that the higher the calcium concentration Y, the smaller the proportion of silicon present as silica, and the less silica impurities there will be.

The glass plate interleaf paper of the present invention is one in which the silica foreign matter in the glass plate interleaf paper can be sufficiently reduced by setting the X/Y ratio to 4.00 or less. The X/Y ratio is preferably 3.50 or less, more preferably 3.00 or less, even more preferably 2.00 or less, particularly preferably 1.00 or less, and most preferably 0.50 or less.

If Y is too large, the amount of silica foreign matter will be reduced, but the amount of calcium-containing foreign matter such as calcium carbonate will increase, which may cause problems. Therefore, Y is preferably 400 ppm or less, more preferably 300 ppm or less, and even more preferably 250 ppm or less.

If Y is too small, the bubbles may not break easily when the glass plate interleaf raw material liquid is stirred, and holes may appear in the glass plate interleaf. Therefore, Y is preferably 20 ppm or more, more preferably 30 ppm or more, and even more preferably 50 ppm or more.

By using virgin pulp with a high calcium content, the X/Y ratio can be reduced.

(Magnesium concentration)
The magnesium contained in glass interleaving paper is mainly derived from the raw materials cellulose pulp and water, and dust in the air that gets mixed in during the manufacturing process. Magnesium is present in the manufactured glass interleaving paper mainly as silicon-containing foreign matter such as talc.

In this specification, the magnesium concentration of the glass sheet interleaf paper measured by X-ray fluorescence analysis is also referred to as Z. Z is measured using the same procedure as described above (Method of measuring silicon concentration X).

The smaller the X/Z ratio, which is the silicon concentration divided by the magnesium concentration, the more magnesium there is relative to silicon. As mentioned above, magnesium exists as a compound containing silicon, such as talc, so it is thought that the larger Z is, the smaller the proportion of silicon present as silica, and the less silica impurities there are.

The X/Z ratio of the glass plate interleaving paper of the present invention is preferably 3.00 or less, more preferably 2.50 or less, even more preferably 2.00 or less, and particularly preferably 1.00 or less.

It is also believed that if Z is large, the amount of silica foreign matter will be reduced, but the amount of talc will increase, which may cause problems. Therefore, the magnesium content is preferably 100 ppm or less, and more preferably 70 ppm or less. There is no particular limit to the lower limit of Z, but it is preferably 10 ppm or more, and more preferably 20 ppm or more.

(Method for measuring silicon-containing foreign matter and silica foreign matter)
The silicon-containing foreign matter is measured, for example, by a scanning electron microscope and an energy dispersive X-ray analyzer attached to the scanning electron microscope. As a pretreatment for the measurement, a conductive film treatment of an element not to be measured, such as carbon or platinum, may be performed on a small cut sample. After the slip sheet is set in the scanning electron microscope, an element heavier than carbon, which is the element that mainly constitutes the slip sheet, is identified from the brightness of the image using a backscattered electron detector. In the method using this backscattered electron detector, elements heavier than carbon are generally represented by bright pixels. First, for example, 100 areas of 0.1 mm x 0.1 mm are measured. Next, when measuring the number of silicon-containing foreign matter and silica foreign matter of 1 μm or more and 10 μm or less, foreign matter other than carbon of 1 μm or more is counted. The size of each foreign matter detected by this backscattered electron detector is calculated from the number of pixels, and the elements of each particle with a maximum diameter of 1 μm or more and 10 μm or less are analyzed by an energy dispersive X-ray analyzer, and particles containing 10% or more by weight of silicon among elements other than carbon and oxygen are defined as silicon-containing particles. Particles containing 80% by weight or more of silicon were considered to be silica foreign matter.

When measuring the number of silicon-containing foreign matter between 0.5 μm and 50 μm and silica foreign matter, foreign matter other than carbon that is 0.5 μm or larger was counted and measured in the same manner.

When the longest diameter of silicon-containing foreign matter is less than 1 μm and is sufficiently smaller than the wiring width or pitch width, it is unlikely to cause defects such as disconnection. In addition, it has been found that the smaller the longest diameter of silica foreign matter, the more difficult it is to remove by cleaning, and that silica foreign matter with a longest diameter of 10 μm or less in particular is likely to remain on the surface of the glass plate even after cleaning.

In the slip paper of this embodiment, the number of silicon-containing foreign matter of 0.5 μm or more and 50 μm or less present on at least one of the slip paper surfaces is preferably 2000 pieces/mm2 or ^less , more preferably 1000 pieces/mm2 or ^less , even more preferably 200 pieces/mm2 or ^less , and particularly preferably 20 pieces/mm2 or ^less . It is believed that the fewer silicon-containing foreign matter of 0.5 μm or more and 50 μm or less contained in the slip paper, the fewer problematic silica foreign matter of 1 μm or more and 10 μm or less.

Furthermore, in the slip paper of this embodiment, the number of silicon-containing foreign matter of 1 μm or more and 10 μm or less present on at least one of the slip paper surfaces is preferably 1000 pieces/mm2 or ^less , more preferably 100 pieces/mm2 or ^less , and even more preferably 10 pieces/mm2 or ^less . It is believed that the fewer silicon-containing foreign matter of 1 μm or more and 10 μm or less contained in the slip paper, the fewer silica foreign matter of 1 μm or more and 10 μm or less will also be.

Furthermore, in the slip paper of this embodiment, the number of silica foreign particles having a size of 0.5 μm or more and 50 μm or less present on at least one of the slip paper surfaces is preferably 100 particles/mm2 ^{or less} , more preferably 50 particles/mm2 ^{or less} , even more preferably 20 particles/mm2 or ^less , and particularly preferably 10 particles/mm2 ^or less. It is considered that the fewer the silica foreign particles having a size of 0.5 μm or more and 50 μm or less contained in the slip paper, the fewer the silica foreign particles having a size of 1 μm or more and 10 μm or less.

Furthermore, in the slip sheet of this embodiment, the number of silica foreign particles having a size of 1 μm or more and 10 μm or less present on at least one surface of the slip sheet is preferably 50 particles/mm2 ^{or less} , more preferably 30 particles/mm2 or less, even more preferably 10 particles/mm2 or ^less , and particularly preferably 5 particles/mm2 ^or less. The fewer the silica foreign particles having a size of ^{1 μm} or more and 10 μm or less, the less the silica foreign particles are transferred to the glass plate, and problems such as disconnection are less likely to occur.

(Air permeability resistance)
The air permeability resistance is measured by a method conforming to JIS P8117. The air permeability resistance is preferably 5 seconds or more, more preferably 10 seconds or more, and particularly preferably 15 seconds or more. When the air permeability resistance is 5 seconds or more, it is easy to remove only one interleaf sheet from the glass plate package with a vacuum suction pad. On the other hand, when the air permeability resistance is less than 5 seconds, when an attempt is made to remove the interleaf sheet from the glass plate package with a vacuum suction pad, an abnormality such as simultaneously removing the glass plate under the interleaf sheet to be removed is likely to occur. In addition, the upper limit of the air permeability resistance is not particularly limited, but is preferably 50 seconds or less, more preferably 45 seconds or less, and even more preferably 40 seconds or less.

(Characteristics of glass plate interleaving paper)
The basis weight of the glass plate interleaf is measured by a method conforming to JIS P8118. A smaller basis weight of the interleaf is preferable because the mass during transportation is smaller, but if it is too small, sufficient cushioning properties cannot be obtained. Therefore, the basis weight of the interleaf is preferably 10 g/ ^m2 or more, more preferably 20 g/m2 or ^more , and even more preferably 30 g/m2 or ^more . Moreover, if the basis weight of the interleaf is too large, the mass during transportation is large, which is not preferable. Therefore, the basis weight of the interleaf is preferably 100 g/ ^m2 or less, more preferably 90 g/m2 ^{or less} , and even more preferably 80 g/m2 or ^less .

From the viewpoint of cushioning properties, the thickness of the slip sheet is preferably 50 μm or more and 200 μm or less, and the density of the slip sheet is preferably 0.30 g/cm ³ or more and 1.00 g/cm ³ or less.

(Glass Sheet Laminate)
The glass plate laminate 12 of this embodiment has at least two glass plates 14 laminated together, with the glass plate interleaving paper 16 according to the present invention between adjacent glass plates.

(Glass plate package)
The glass sheet package 10 of this embodiment includes a glass sheet laminate 12 and a pallet on which the glass sheet laminate 12 is placed.

The pallet is a known pallet for packaging glass sheets, and has a base 22, an inclined platform 18 installed on the upper surface of the base 22, and a mounting platform 24 that supports the end faces of the glass sheet laminate 12. The angle θ between the mounting platform 24 and the inclined platform 18 is not particularly limited as long as the glass sheets 14 can be stably loaded, but 90° is preferable.

The angle γ of the inclined platform 18 is the angle between the inclined platform 18 and the horizontal plane. That is, when the top surface of the base on which the inclined platform 18 and the mounting platform 24 are installed is horizontal as shown in FIG. 1, 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, but since a large pressure is applied to the edge of the glass plate 14, defects such as chipping may occur. In addition, the closer the angle γ of the inclined platform 18 is to 0°, the more the pressure applied to the glass plate 14 is dispersed, and defects such as chipping of the edge can be suppressed, but since a large space is required, the efficiency of storage and transportation decreases. In this specification, a pallet with an angle of the inclined platform 18 of 10° or less is called a flat-stacked pallet, and a pallet with an angle of more than 10° is called a vertical-stacked pallet.

The pallet used may be a flat-stacked pallet or a vertical-stacked pallet, but in the case of a large glass plate, the weight of the glass plate 14 exerts a large pressure on the edge of the glass plate 14. Therefore, in the case of a large glass plate, 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 14, the greater the pressure exerted on the edge of the glass plate 14, the angle of the inclined platform is preferably 0° or more and 5° or less, more preferably 0° or more and 3° or less, and even more preferably 0° or more and 1° or less. However, when storing the glass plate 14 in a truck or container for transporting the glass plate 14, there are cases in which a flat-stacked pallet cannot be used. Therefore, a vertical-stacked pallet may be used to save space.

A large glass plate is, for example, a glass plate with at least one side of 2400 mm or more, and a specific example is a glass plate with 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 with at least one side of 2400 mm or more, for example, a glass plate with a long side of 2400 mm or more and a short side of 2100 mm or more, more preferably a glass plate with at least one side of 3000 mm or more, for example, a glass plate with a long side of 3000 mm or more and a short side of 2800 mm or more, even more preferably a glass plate with at least one side of 3200 mm or more, for example, a glass plate with a long side of 3200 mm or more and a short side of 2900 mm or more, and particularly preferably a glass plate with at least one side of 3300 mm or more, for example, a glass plate with a long side of 3300 mm or more and a short side of 2950 mm or more.

The thickness of the glass plate 14 is preferably 1 mm or less. By making the glass plate 14 thinner, weight reduction can be achieved. The thickness of the glass plate 14 of the present invention is more preferably 0.75 mm or less, even more preferably 0.6 mm or less, particularly preferably 0.5 mm or less, and most preferably 0.4 mm or less. The thickness can also be 0.1 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 0.1 mm or more, and more preferably 0.2 mm or more.

The glass plate 14 is preferably used for a display. Since there is little silica foreign matter of 1 μm or more and 10 μm or less present on the main surface of the glass plate 14, defects such as breakage can be suppressed. As a display, it is preferably used as a substrate for a liquid crystal display.

The glass plate interleaving paper 16, the glass plate laminate 12, and the glass plate package 10 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 without departing from the spirit of the present invention.

<Example>
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 4 are examples, and Examples 5 to 7 are comparative examples. Unless otherwise specified, the manufactured slip sheets were treated in accordance with JIS P8111 and then measured.

The silicon concentration, magnesium concentration, and calcium concentration contained in the slip papers of Examples 1 to 7 were each measured twice using X-ray fluorescence analysis, and the average values were calculated. Next, a scanning electron microscope and an energy dispersive X-ray analyzer attached to the scanning electron microscope were used to measure the number of silicon-containing foreign matter having a maximum diameter of 0.5 μm to 50 μm and 1 μm to 10 μm (pieces/mm ² ), and the number of silica foreign matter having a maximum diameter of 0.5 μm to 50 μm and 1 μm to 10 μm (pieces/mm ² ). The silicon-containing foreign matter and silica foreign matter of each size were each measured twice using different slip papers, and the average values were calculated.

The glass plate interleaving papers of Examples 1 to 7 were molded into a size of 2330 mm x 1990 mm, each with a thickness of 0.5 mm, and placed between glass plates for FPDs measuring 2250 mm x 1950 mm to form a glass plate laminate in which multiple glass plates were laminated.

Each glass plate stack was placed on a vertically stacked pallet as shown in Figure 2 (600 glass plates) to produce a glass plate package. The produced glass plate package was stored for 10 days.

The glass plate closest to the pallet's inclined platform was removed from the glass plate package, and after cleaning, the number of foreign objects remaining on the surface of the glass plate was measured using an optical inspection machine.

Each measurement was performed using the following methods.

<Measurement of element concentration of glass plate interleaving paper by fluorescent X-ray analysis>
The approximate center of the interleaf was measured using a fluorescent X-ray analyzer (manufacturer: Rigaku Corporation, model: ZXS PRIMSII). Next, a reference sample with a known concentration was measured in advance to quantify the detected elements, and the numerical value of each element was corrected from the X-ray intensity. The power during the measurement was 3000 W, and the contents of each element, magnesium, aluminum, silicon, and calcium, were quantified.

<Measurement of the number of silicon-containing foreign particles and silica foreign particles contained in glass plate interleaving paper>
The silicon-containing foreign matter contained in the slip paper was measured at approximately the center of the slip paper using a scanning electron microscope (manufacturer: JEOL Ltd., model: JSM-6490LA) and an energy dispersive X-ray analyzer (manufacturer: Oxford Instruments Ltd., model: X-MAXN50). The accelerating voltage during observation was 20 kV.

When measuring silicon-containing foreign matter with a maximum diameter of 0.5 μm to 50 μm and silica foreign matter, first, 100 areas of 0.1 mm x 0.1 mm were measured, and foreign matter other than carbon with a maximum diameter of 0.5 μm or more was counted. The size of each foreign matter detected by the backscattered electron detector was calculated from the number of pixels, and the elements of each particle with a maximum diameter of 0.5 μm to 50 μm was analyzed using an energy dispersive X-ray analyzer, and the number of particles containing 10% or more by weight of silicon (silicon-containing foreign matter) and particles containing 80% or more by weight of silicon (silica foreign matter) were counted, among elements excluding carbon and oxygen.

The same measurements were also performed when measuring silicon-containing foreign matter and silica foreign matter with a maximum diameter of 1 μm or more and 10 μm or less.

<Measurement and evaluation of foreign matter remaining on the glass plate surface>
The glass plate closest to the inclined platform of the pallet was removed from the glass plate package stored for 10 days, and the glass plate was washed and then the number of foreign bodies remaining on the surface of the glass plate was measured using an optical inspection machine (manufacturer: Hitachi High-Tech Fine Systems Co., Ltd., model: GI). The glass plate was washed by rubbing it with a PVA sponge while spraying it with pure water while transporting the glass plate horizontally.

If there were less than 50 foreign objects on the surface of the glass plate, it was rated as A, if there were between 50 and 60 foreign objects, it was rated as B, and if there were 60 or more foreign objects, it was rated as C.

(Example 1, Example 2)
A raw material solution for the interleaf paper was obtained by diluting virgin pulp with a high calcium content as a raw material with groundwater filtered through a process filter with a filtration accuracy of 200 μm. The raw material solution was spread to a uniform thickness and dehydrated to obtain a wet paper. The obtained wet paper was dehydrated by pressing with a press roller, and the pressed wet paper was dried in an atmosphere of about 120° C. to obtain the interleaf paper.

(Example 3, Example 4)
The production was carried out in the same manner as in Example 1, except that virgin pulp having a high silicon content was used as the raw material.

(Example 5)
The production was carried out in the same manner as in Example 1, except that virgin pulp having a high silicon content and a low calcium content was used as the raw material.

(Example 6, Example 7)
The production was carried out in the same manner as in Example 1, except that virgin pulp containing talc and having a high concentration of silicon and magnesium was used as the raw material.

<Results>
Table 1 shows the measurement results and the evaluation results. According to Table 1, when the silicon concentration was 200 ppm or less and the X/Y ratio obtained by dividing the silicon concentration by the calcium concentration was 4.00 or less, the fouling level was A or B. On the other hand, when the silicon concentration was more than 200 ppm and the X/Y ratio was greater than 4.00, the fouling level was C in all cases.

From these results, it can be seen that the silicon concentration and the X/Y ratio are related to the number of silica particles present in the interleaf and the contamination of the glass plate.

10...glass sheet package, 12...glass sheet laminate, 14...glass sheet, 16...glass sheet interleaf, 18...inclined table, 22...base, 24...mounting table, 42...interleaf roll, 100...glass sheet interleaf manufacturing device, 112...head box, 114...wire part, 116...lower wire, 118...upper wire, 120...press part, 124...dryer part, 126...calendar part, 128...reel, 130...jumbo roll, 134...cutter, 136...winder.

Claims (10)

The main component is cellulose pulp.
A glass plate interleaving paper having a basis weight of 10 g/m2 or ^more and 100 g/m2 or ^less ,
In the glass plate interleaving paper, when the silicon concentration measured by X-ray fluorescence analysis is X and the calcium concentration measured by Y are:
X is 10 ppm or more and 150 ppm or less ,
Y is 20 ppm or more and 400 ppm or less,
1. A glass plate interleaving paper, characterized in that the X/Y ratio, which is the value obtained by dividing the silicon concentration by the calcium concentration, is 4.00 or less. In the glass plate interleaving paper, when the magnesium concentration measured by fluorescent X-ray analysis is Z,
2. The glass plate interleaving paper according to claim 1, wherein an X/Z ratio, which is a value obtained by dividing a silicon concentration by a magnesium concentration, is 3.00 or less. The glass plate interleaving paper according to claim 2, wherein Z is 20 ppm or more and 100 ppm or less. The glass plate interleaving paper according to any one of claims 1 to 3 , wherein the number of silicon-containing foreign matter having a size of 0.5 μm or more and 50 μm or less present on at least one surface of the glass plate interleaving paper is 2000 pieces/mm2 ^or less. The glass plate interleaving paper according to any one of claims 1 to 4 , wherein the number of silicon-containing foreign matter having a size of 1 μm or more and 10 μm or less present on at least one surface of the glass plate interleaving paper is 1000 pieces/mm2 or ^less . The glass plate interleaving paper according to any one of claims 1 to 5 , wherein the number of silica foreign particles having a size of 0.5 μm or more and 50 μm or less present on at least one surface of the glass plate interleaving paper is 100 pieces/mm2 ^or less. The glass plate interleaving paper according to any one of claims 1 to 6 , wherein the number of silica foreign particles having a size of 1 μm or more and 10 μm or less present on at least one surface of the glass plate interleaving paper is 50 pieces/mm2 or ^less . The glass plate interleaving paper has an air resistance of 5 seconds or more.
The glass plate interleaving paper according to any one of claims 1 to 7 . A glass plate laminate in which at least two glass plates are laminated,
A glass plate laminate having the glass plate interleaving paper according to any one of claims 1 to 8 between adjacent glass plates. A glass sheet package comprising: the glass sheet laminate according to claim 9 ; and a pallet on which the glass sheet laminate is placed.

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