JP2016191162A - Wood pulp for glass slip sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wood pulp for glass slip sheet capable of preventing scratch or crack generated on a glass sheet surface for a wood pulp which becomes a raw material for a glass sheet used as a substrate material for flat panel displays requiring high cleanliness or scratch grade.SOLUTION: There is provided a wood pulp for glass slip sheet having 0.3/mof debris with Mohs hardness 4 or less existing on a surface of a hand-made paper manufactured by a method according to JIS P8222 using wood pulp. The debris contains metal oxide or inorganic silicon oxide.SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to a wood pulp used for paper for wrapping a glass plate and paper sandwiched between glass plates (also referred to as “glass interleaving paper”) in the process of transporting and storing the glass plate. . In particular, the present invention can be suitably used as a wood pulp for glass interleaving paper for flat panel displays such as liquid crystal panel displays, plasma displays, and organic electroluminescence (organic EL) displays.

  In general, in the process of laminating and storing a plurality of glass plates, the distribution process of transporting the glass plates with a truck, etc., the glass plates may be subjected to impact and contact with each other, and the surface of the glass plates may be damaged or cracked. There is.

  In particular, glass plates for flat panels and displays are used for high-definition displays compared to general architectural window glass plates and vehicle window glasses, so the glass surface is clean and free from scratches or cracks. As well as excellent flatness for high speed response and wide viewing angle. For example, even if the scratches or cracks on the surface of the glass plate are minute, there are problems such as no element being formed at that location and wiring being cut. Therefore, there is a method in which an interleaving paper (glass interleaving paper) is sandwiched between glass plates for the purpose of preventing scratches or cracks on the glass surface.

  As a glass interleaving paper used in such applications, several interleaving papers that can prevent a glass plate from cracking or scratching the surface, and that do not contaminate the glass surface have been proposed. For example, Patent Document 1 discloses a technique for forming a fluorine coating film on the surface of a slip sheet. Further, Patent Document 2 is a paper made of a pulp containing a polyethylene resin foam sheet and a polyethylene resin film, and Patent Document 3 is a pulp made of pulp containing 50% by mass or more of bleached chemical pulp. In addition, a paper for glass containing a specific alkylene oxide adduct or water-soluble polyether-modified silicone is disclosed in Patent Document 4, which defines the amount of resin in the paper and includes raw materials that are taken into consideration for contamination countermeasures on the glass surface. Each used glass slip is disclosed.

JP 2012-188785 A JP 2010-242057 A JP 2008-208478 A JP 2006-44674 A

  However, even if slip sheets are used for the purpose of preventing scratches and cracks on the glass plate, these cannot be completely prevented, and in some cases, such as scratches and cracks on the surface of the glass plate due to some cause. Therefore, the fact is that the defect rate of the glass plate may increase.

  In particular, glass plates used for flat panel displays are more likely to be broken or short-circuited if they have minute scratches or cracks on their surfaces, so scratches or cracks on glass plates are more likely to occur than conventional glass interleaving paper. There is a need for slip-sheets. Further, since the glass plate surface serves as an image display surface, cleanliness and beauty are also required, and from this point, it is necessary to have few scratches, cracks, and the like. And if the defect rate rises due to these scratches and cracks, it also becomes a problem from the viewpoint of profitability, so how to prevent scratches and cracks on the surface of glass plates used for flat panel displays, how high yield Whether to realize is a big issue.

  Accordingly, the present invention provides a wood pulp for slip sheets, which can significantly prevent cracks or scratches on the glass surface for glass plates used as substrate materials for flat panel displays that require high scratch quality. It is an issue to provide.

  For example, when a color filter substrate in an array process, which is one of the TFT liquid crystal display manufacturing processes, is cracked or scratched on the glass plate surface, problems such as disconnection may occur. The color filter substrate is produced by forming a thin film such as a semiconductor film, an ITO film (transparent conductive film), an insulating film, an aluminum metal film, or the like on a glass plate by sputtering or vacuum evaporation, etc. This is because the presence of scratches or the like increases the possibility that a circuit pattern formed from a thin film will be disconnected or that a short circuit will occur due to a defect in the insulating film. In the production of a color filter substrate, a photolithography pattern is formed on a glass plate. If cracks or scratches are present on the glass plate surface during resist application in this process, pinholes are formed in the resist film after exposure or development. Or a partial defect may occur, resulting in disconnection or short circuit. The cause of such cracks or scratches on the glass plate has been difficult to identify, but the present inventors have a correlation between the Mohs hardness of foreign matter present on the surface of the glass interleaving paper and the cracks or scratches generated on the glass plate surface. It became clear for the first time by these verifications. It was also found that even if the foreign matter is minute, the surface of the glass plate is scratched and scratched when the glass plate or the interleaf moves, and the fine scratch remains as a scar for a long time. Therefore, the present inventors have found that the above-mentioned problems can be solved by making the foreign matter having a Mohs hardness of 4 or more in the wood pulp used for the production of the glass interleaving paper constant, and have completed the present invention.

That is, the present invention is a wood pulp for glass interleaving paper, and 0.3 foreign matter having a Mohs hardness of 4 or more present on the surface of a handsheet prepared by the method according to JIS P8222 using the wood pulp. It is related with the wood pulp for glass interleaving paper which is less than / m < ² >.

  The foreign matter preferably contains a metal oxide or a silicon oxide. The silicon oxide is preferably silicon dioxide.

  More preferably, the foreign matter is one or more selected from the group consisting of iron oxide, copper, quartz, fused quartz, titanium oxide, glass pieces, crystal pieces, magnesium oxide and sand.

The volume of the foreign matter is preferably less than 2 × 10 ⁻⁵ mm ³ .

  The glass is preferably used for a display.

  The display is preferably a TFT liquid crystal display or an organic EL display.

  When glass interleaving paper using the wood pulp of the present invention is used for a glass plate, even if the glass interleaving paper contacts the glass plate surface, it is possible to prevent scratches on the glass plate surface. The production yield of the board can be improved. And the said glass interleaving paper can suppress the generation | occurrence | production of the damage | wound or a crack of a glass plate as much as possible. Thereby, for example, it becomes possible to prevent circuit disconnection of a color film or the like in the manufacturing process of the TFT liquid crystal.

The wood pulp for glass interleaving paper of the present invention has less than 0.3 / m ² of foreign matter having a Mohs hardness of 4 or more present on the surface of the handsheet prepared by the method according to JIS P8222. When glass interleaving paper is used on a glass plate, foreign matter on the surface of the interleaving paper tends to come into contact with and damage the glass plate, and in particular, pulp containing the above foreign matter is 0.3 pieces / m ² or more as a raw material. It has been clarified this time that when the glass interleaving paper used as a glass plate is used for a glass plate, the fine scratches or cracks generated on the surface of the glass plate are remarkably increased, resulting in problems at the time of panel formation.

In order to make the foreign matter having a Mohs hardness of 4 or more present in the wood pulp for glass interleaving paper less than 0.3 / m ² , examination and management of chemicals and the like at the time of pulp production are important.

  Generally, various foreign substances are contained in wood pulp. For example, foreign materials derived from wood, which is the raw material for wood pulp, foreign materials derived from cooking chemicals during pulp production, foreign materials derived from chemicals used in unbleached cleaning processes, metallic foreign materials derived from waste paper materials, or used in each process This may be caused by water-derived foreign matter. Therefore, in the present invention, washing and selection of pulp are particularly important, and it is necessary to remove foreign matters at a high level.

  In general, in the pulp manufacturing process, pulp obtained by cooking wood chips is delignified, and then the pulp is washed and further bleached. Therefore, first, foreign matters are removed and washed at the stage of wood chips. For example, it is preferable to remove foreign matters such as metal and sand with a known foreign matter removing system such as a tip washer. In the pulp manufacturing process, the purpose of washing after cooking is to remove cooking chemicals, lignin degradation products and colored components remaining in the pulp liquid, but it is also possible to remove foreign substances at the same time. For example, a known method such as a countercurrent cleaning method using various cleaning devices such as a vacuum filter cleaning machine, a pressure drum type filter cleaning machine, a press type cleaning machine, and a diffuser cleaning machine can be employed. In particular, in order to remove foreign substances and improve the cleanness of the pulp, it is preferable to increase the amount of washing water used or to use a multi-stage washing system having two or more rinse washing stages. In addition, it is more preferable not to use the substance which causes a foreign material as chemical | medical agents, such as surfactant used at the time of washing | cleaning, a pH adjuster, a pitch control agent, a chelating agent, and an antifoamer. For example, mineral oil-based antifoaming agents used as antifoaming agents can cause mineral foreign matter in glass interleaving paper, so the amount of mineral oil-based antifoaming agents used can be reduced or replaced with other antifoaming agents. It is preferable.

  There is a bleaching step after the washing step, and it is preferable here to remove foreign matter as much as possible. For example, it is possible to install a cleaning device for each bleaching stage. Also here, a known washing machine can be used. For example, a pressure diffuser, a diffusion washer, a pressure drum washer, a horizontal long washer, a press washing machine, or the like can be used. In particular, by using a plurality of these, various kinds of foreign matters can be highly removed. Although chemicals such as alkalis, acids, chelating agents, surfactants, and antifoaming agents can be added to the washing water, it is preferable not to use chemicals that cause foreign substances. In addition, it is preferable to take measures to prevent contamination by foreign matter between the processes. It is even more preferable to combine the iron removal methods described later.

  Although it is possible to employ waste paper pulp in the present invention, it is preferable to pay attention to reducing the use ratio of waste paper pulp because it often contains foreign matters. In particular, in the waste paper pulp manufacturing process, it is more preferable to remove foreign substances such as metals at a high level with a pulper, a screen, a cleaner, or the like.

  Iron, which is one of the causes of foreign matter, becomes iron oxide with high Mohs hardness by mixing iron powder and iron rust due to friction and corrosion from pipes of pulp manufacturing equipment and oxidizing it, so iron is selectively used. It is preferable to remove it. For example, each facility is made of a material other than iron, or a high magnetic material such as a magnet is installed in the system to selectively remove iron, or the adsorbent that selectively adsorbs iron It is preferable to arrange on the exit side of each facility. The selective removal method by installing a high magnetic material can remove not only iron but also other magnetic materials.

  The wood pulp usable in the present invention includes softwood bleached kraft pulp (NBKP), hardwood bleached kraft pulp (LBKP), softwood bleached sulfite pulp (NBSP), hardwood bleached sulfite pulp (LBSP), thermomechanical pulp ( A wood pulp such as TMP) or a mixture thereof is used. As the raw material wood, it is preferable to select a production area and tree species that do not contain a large amount of foreign matter. These wood pulps are the main components. Synthetic fibers such as acrylic and polyester, chemical fibers, or microfibrillated pulp can be used alone or in combination. However, if the pulp contains a large amount of resin, the resin may contaminate the glass plate surface. Therefore, chemical pulp with as little resin as possible, for example, softwood bleached kraft pulp, is used alone. It is preferable to do. Also, high yield pulp such as groundwood pulp is not preferred because it contains a large amount of resin. In addition, mixing synthetic fibers and chemical fibers improves cutting performance and improves workability when making interleaf paper flat, but care must be taken because recyclability deteriorates in terms of waste disposal. is there.

  The foreign matter having a Mohs hardness of 4 or more in the present invention may be particles made of any inorganic or organic substance, and inorganic particles are preferred. Examples of the foreign material include metal oxides or inorganic silicon oxides having a Mohs hardness of 4 or more. The metal constituting the metal oxide is not particularly limited as long as the Mohs hardness of the oxide is 4 or more. For example, a Group 2 element such as magnesium, a Group 4 element such as titanium, iron, etc. Group 8 elements such as As the inorganic silicon oxide, silicon dioxide is preferable. Examples of the foreign matters having a Mohs hardness of 4 or more include oxide minerals. Examples of the foreign matters having a Mohs hardness of 4 or more include iron oxide, copper, quartz, fused quartz (quartz glass), titanium oxide, glass pieces, crystal pieces, magnesium oxide, and sand. The sand is mainly composed of amphibole with a Mohs hardness of 5.5, feldspar with a Mohs hardness of 6 and quartz with a Mohs hardness of 7. Therefore, the Mohs hardness of sand is 4 or more, typically 7. Mohs hardness is an index of hardness expressed in 10 levels. Rubbing the standard material and the material to be measured against each other, the hardness of the standard material is relatively determined by whether or not it is scratched. It is the evaluated value. The standard materials were soft (Mohs hardness 1) to hard (Mohs hardness 10) in the order of 1: talc, 2: gypsum, 3: calcite, 4: fluorite, 5: apatite, 6: feldspar, 7: quartz 8: Topaz, 9: Corundum, 10: Diamond. The Mohs hardness is measured by preparing two plates having a smooth surface and a known Mohs hardness, sandwiching a foreign substance to be measured between the two plates, and rubbing both plates to check for the presence or absence of scratches on the plate surface.

  Examples of such foreign substances that are easily contained in wood pulp and that may damage the surface of the glass plate include quartz having a Mohs hardness of 7, quartz, fused quartz, sand and crystal pieces, magnesium oxide having a Mohs hardness of 6, and titanium oxide. And iron oxide, copper having a Mohs hardness of 5-8, and glass pieces having a Mohs hardness of 4-7.

In the present invention, the volume of the foreign matter is preferably controlled to less than 0.00002Mm ^3, less than 0.00001mm ³ is more preferable. Unlike dirt, foreign matter is present as a three-dimensional object on the surface or inside of a slip sheet, causing problems. In particular, when the size of the foreign matter is 0.00002 mm ³ or more, there is a possibility that the foreign matter may come into contact with the surface of the glass plate and leave scratches or cracks when using the glass interleaf made from the wood pulp of the present invention. Tend to be higher. For example, when glass interleaving paper and a glass plate are laminated, foreign matter present on the surface of the interleaving paper may be pressed depending on the weight of the glass plate, but if the size of the foreign matter is small, the paper of the interleaving paper may be pressed. Since foreign matter is buried inside, the possibility of scratching the glass plate surface is reduced. In addition, since the foreign material is a three-dimensional object as described above, particularly when the projection area is small, there is a scratch that can be visually observed as a scratch generated when the glass or the glass interleaf moves. There is a risk of leaving. On the other hand, if the projected area is large even if the height is low, the surface of the glass plate may be damaged, which is not preferable.

  The foreign matter preferably has a sphere volume equivalent diameter average particle size of 30 μm or less, more preferably 20 μm or less, even more preferably 10 μm or less, and even more preferably 5 μm or less, It is especially preferable that it is 1 micrometer or less. The equivalent sphere volume diameter is a diameter of the sphere when foreign particles are converted to a sphere having the same volume, and can be measured by a laser diffraction method or the like.

  The glass slip paper using the pulp for glass slip paper of the present invention is used by being inserted or packaged between glass plates. For example, the glass interleaving paper is typically inserted one by one between a plurality of glass plates to form a laminated body as a whole, and the laminated body is a target for storage and transportation.

  Although it does not specifically limit as a glass plate, It is preferable that it is a glass plate for flat panel displays, such as a plasma display panel, a liquid crystal display panel (especially TFT liquid crystal display panel), and an organic electroluminescent display panel. Fine electrodes, partition walls, etc. are formed on the surface of the glass plate for flat panel display, but by using the glass interleaving paper made from the wood pulp of the present invention, scratches or cracks on the surface of the glass plate Therefore, even if fine electrodes, partition walls, or the like are formed on the surface of the glass plate, inconvenience due to scratches or cracks can be suppressed or avoided, and as a result, display defects can be suppressed or avoided. can do.

  In particular, as the size of the display increases, the size and weight of the glass plate for the flat panel display has increased, but the glass interleaf using the wood pulp of the present invention is such a large to large glass plate. Can be well protected. In particular, since the surface of the glass interleaving paper has very few foreign substances having high hardness, it is possible to prevent or prevent the foreign substances from scratching the glass plate surface even when pressed by a heavy glass plate. Therefore, the glass interleaving paper manufactured using the wood pulp of the present invention as a raw material can be suitably used for a glass plate for a flat panel display in which surface scratch quality and cleanliness are particularly required.

  The present invention provided in the above configuration is very suitable particularly when used as a raw material for glass interleaving papers used for glass plates for flat panels and display substrates.

  That is, since a desired film such as an alignment film is formed on the surface of the glass plate for a flat panel display substrate, the prevention of scratches is greatly required, and the glass surface becomes an image display surface. It is required to be beautiful and beautiful, and since it may be exported to foreign markets, it must also be able to withstand long-term transportation and long-term storage. About this, when using the glass interleaving paper produced using the wood pulp of the present invention as a raw material, even if the glass interleaving paper and the glass plate are in contact with each other over a long period of time, the glass plate surface is not damaged, Since blocking with the glass plate does not occur, the above requirements can be met accurately.

  A well-known means is used for the method of manufacturing glass interleaving paper using the wood pulp for glass interleaving paper of this invention as a raw material. For example, for papermaking fibers mainly composed of wood pulp of the present invention, adhesives, antifungal agents, various papermaking fillers, wet paper strength enhancers, dry paper strength enhancers, sizing agents, if necessary. Coloring agents, fixing agents, yield improvers, slime control agents and the like can be added. The papermaking fibers and the like can then be made with a known / existing long net paper machine, circular net paper machine, short net paper machine, long net and circular net combination paper machine, etc. to obtain glass interleaving paper. However, as described above, since it is necessary to prevent the glass plate from being scratched or cracked due to contamination by foreign matter, it is preferable not to add the chemicals and fillers as much as possible. For example, paper fillers such as titanium oxide are not suitable because of their high Mohs hardness.

  When producing the glass interleaving paper, if the beating of the wood pulp is advanced, the effect of increasing the paper interlayer strength can be expected. However, if the fine fibers in the wood pulp increase as the beating progresses, paper dust may be generated during use as a slip sheet, so it is not preferable to advance the beating degree more than necessary. A preferred beating degree is 300 to 650 ml c. s. f. It is.

In the present invention, the number of foreign matters having a Mohs hardness of 4 or more present on the surface of a handsheet prepared by a method according to JIS P8222 using wood pulp for glass interleaving paper is less than 0.1 / m ^2. Is preferably less than 0.08 / m ² , more preferably less than 0.04 / m ² , and even more preferably less than 0.01 / m ² . When there is more than a predetermined amount of foreign matter, the color film breaks caused by scratches or cracks on the glass surface are highly detailed in scenes that require very high-definition displays such as mobile devices. Therefore, it is conspicuous and there is a risk of being judged as a quality defect.

Glass slip sheet preferably has a basis weight of 20 to 100 g / ^{m 2,} more preferably 30~90g / ^{m 2,} still more preferably 40 and 80 g / ^{m 2.} If it is less than 20 g / m ^2, it is difficult to maintain the minimum air permeability resistance (more than 5 seconds), and there is a risk of sucking up to the glass plate body when only the glass interleaving paper is sucked and removed after use on the glass plate. Occurs. Further, if it is less than 20 g / m 2, the waist of the glass interleaving paper itself becomes weak and the handling property is also deteriorated, which is not preferable. On the other hand, when the basis weight exceeds 100 g / m ² , the flexibility as the glass interleaving paper is impaired and the handling property is deteriorated. In addition, glass slips are used for the purpose of transporting, protecting, scratching, and preventing contamination during storage of glass plates used, so increasing the basis weight more than necessary is disadvantageous in terms of cost and workability. Also decreases.

  The thickness of the glass interleaving paper is preferably 0.030 to 0.130 mm, more preferably 0.040 to 0.120 mm, and even more preferably 0.050 to 0.110 mm. If it is less than 0.030 mm, the protective effect during transportation and storage of the glass plate to be used decreases, which is not preferable. In particular, it is difficult to sufficiently exhibit a buffer function as a slip sheet, and there is a possibility that it is easily torn due to being too thin. On the other hand, when the thickness exceeds 0.130 mm, the thickness of the laminate of the glass plate and the glass interleaving paper is increased, so that the occurrence of storage space, transportation problems, and the like is predicted.

  The water content of the glass interleaving paper is preferably 2 to 10% by mass, more preferably 3 to 9% by mass, and even more preferably 4 to 8% by mass. If the water content is less than 2% by mass, the glass interleaf itself tends to be charged with static electricity, and a blocking phenomenon due to static electricity occurs between the glass plate and the glass sheet. On the other hand, if the water content exceeds 10% by mass, the dimensional stability may be deteriorated due to a blocking phenomenon with a glass plate due to excessive water content or a decrease in water content during use.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely using an Example and a comparative example, the scope of the present invention is not limited to an Example.

(1) Investigation of foreign matter in wood pulp for glass interleaving paper Hand scrubbing is performed in accordance with JIS P8222, and the presence ratio of foreign matter having a Mohs hardness of 4 or more present on the surface of 100 sheets of the obtained handsheet 45 g / m ² is obtained. Examined. First, a foreign object was searched for with a stereomicroscope, the size of the foreign object was measured to calculate the volume, and then the material of the foreign object was specified using an X-ray analysis microscope.

(2) Method for producing glass interleaving paper 100 parts by weight of wood pulp for glass interleaving paper is prepared and disaggregated to give a beating degree of 520 mlc. s. f. 0.4 parts by mass of polyacrylamide (trade name: Polystron 1250, manufactured by Arakawa Chemical Industries, Ltd.) as a paper strength enhancer was added to the prepared slurry, and a 0.4% concentration pulp slurry was added. Prepared. This was used to obtain glass interleaving paper having a basis weight of 50 g / m ² using a long web paper machine.

(3) Evaluation of scratches generated on glass surface 100 glass substrates for liquid crystal displays having a size of 1500 mm × 1800 mm × 0.7 mm and the above-mentioned glass interleaving paper were alternately laminated. An acrylic plate having the same size and a thickness of 1 mm was sandwiched between the upper and lower sides of the laminate, and the entire laminate was fixed with a rubber string. The resulting laminate was shaken and shaken at 300 rpm for 24 hours. Then, the rubber string was unwound and light was applied from the side surface of the glass, and it was confirmed using a microscope whether there were any scratches on the front and back surfaces of 100 glass plates.

[Example 1]
In a conifer bleached kraft pulp manufacturing apparatus comprising a cooking process, a washing process, an oxygen delignification reaction process, and a multistage bleaching bleaching process using chlorine dioxide and hydrogen peroxide, 10000 in the pulp transfer line after the multistage bleaching process A metal removing device in which a plurality of Gaussian magnet bars were arranged was provided to remove metal foreign matters such as iron present in the pulp slurry. The wood pulp for glass interleaving paper was obtained by the above process.

[Examples 2 and 3]
In the same manner as in Example 1, the wood pulp for glass interleaving paper of Example 2 and Example 3 was obtained as a separate lot.

[Comparative Example 1]
Moreover, the wood pulp manufactured similarly to the above was obtained except not using the in-line box which arranged the said magnet bar.

[Comparative Examples 2 and 3]
In the same manner as in Comparative Example 1, the wood pulp for glass interleaving paper of Comparative Example 2 and Comparative Example 3 was obtained as a separate lot.

  It shows in Table 1 about the foreign material of the wood pulp for glass interleaving paper obtained by the Example and the comparative example.

  About the glass interleaving paper manufactured using the wood pulp obtained by the Example and the comparative example, said "evaluation of the damage | wound which generate | occur | produces on the glass surface" was performed. No scratches or cracks were observed on the surface of the glass plate using the glass slip paper using the wood pulp of Examples 1 to 3. When forming an array of a liquid crystal panel using this glass plate, no disconnection of the color film was observed. On the other hand, a plurality of minute scratches were confirmed on the surface of the glass plate using the glass interleaving paper using the wood pulp of Comparative Examples 1 to 3, respectively. Furthermore, disconnection of the color film was observed when forming an array of a liquid crystal panel using a glass plate using the glass interleaving paper.

From the above results, the wood pulp for glass interleaving paper of the present invention has less than 0.3 / m ² of foreign matter having a Mohs hardness of 4 or more present on the surface of the handsheet prepared by a method according to JIS P8222. Therefore, even if the glass paper made from the wood pulp is used for the glass plate, it can suitably serve as the paper without causing scratches or cracks that cause problems on the surface of the glass plate. It becomes possible to manufacture a glass plate that favorably forms an array of liquid crystal panels.

Claims (7)

It is wood pulp for glass interleaving paper, and there are less than 0.3 pieces / m ² of foreign matter having a Mohs hardness of 4 or more present on the surface of a handsheet prepared by the method according to JIS P8222 using the wood pulp. , Wood pulp for glass interleaving paper.   The wood pulp for glass interleaving paper according to claim 1, wherein the foreign matter contains a metal oxide or an inorganic silicon oxide.   The wood pulp for glass interleaving paper according to claim 2, wherein the inorganic silicon oxide is silicon dioxide.   2. The glass interleaving paper according to claim 1, wherein the foreign substance is one or more selected from the group consisting of iron oxide, copper, quartz, fused quartz, glass pieces, crystal pieces, magnesium oxide, titanium oxide, and sand. Wood pulp. The volume of foreign substances is less than 2 × 10 ^-5 mm ^3, the glass slip sheet wood pulp according to any one of claims 1 to 4.   The wood pulp for glass interleaving paper according to any one of claims 1 to 5, wherein the glass is a glass plate for display.   The wood pulp for glass interleaving paper according to claim 6, wherein the display is a TFT liquid crystal display or an organic EL display.