TW201942449A - Glass plate-interleaving paper and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an interleaving paper for glass plates, the raw material of which is wood pulp, wherein the existing rate of aluminum-based solid inorganic substances on one surface is less than 20 per 100 m2 and the difference between the existing rates of the aluminum-based solid inorganic substances on one surface and the other surface is within 8 per 100 m2. The interleaving paper according to the present invention can solve problems derived from the difference in the conditions of the front and back surfaces of an interleaving paper for glass plates.

Description

   Spacer paper for glass plate and manufacturing method thereof   

The present invention relates to a paper for packaging glass plates in the process of laminating and storing and transporting several glass plates used in flat panel displays such as liquid crystal displays, plasma displays, and organic electroluminescence (organic EL) displays, and Paper sandwiched between glass plates, and the manufacture of such paper.

In general, in order to prevent the glass plates from being scratched due to the impact of the glass plates on each other during the storage process of laminating and storing several glass plates used for flat panel displays, and the transportation process using rails, etc., The glass surface is contaminated with pollutants from the outside, and a paper called a spacer is sandwiched between the glass plates.

Compared with ordinary building window glass plate and vehicle window glass plate, the glass plate for flat panel display is used for high-definition display. Therefore, the glass surface is required to be kept as a clean surface free of impurities contained in the paper surface as much as possible. In order to achieve high-speed response and wide viewing angle, excellent flatness is required.

As spacer papers used for this purpose, several spacer papers have been proposed which can prevent the glass plate from cracking or surface damage without contaminating the glass surface. For example, Patent Document 1 discloses a method of forming a fluorine-plated film on the surface of a spacer paper. Further, Patent Document 2 discloses a spacer paper in which a polyethylene resin foamed sheet and a polyethylene resin film are bonded. In Patent Document 3, a paper containing 50% by mass or more of bleached chemical pulp is disclosed. Paper made of pulp, which is a spacer paper for glass containing a specific alkylene oxide adduct, water-soluble polyether modified polysiloxane; in Patent Document 4, it is disclosed that The amount of the resin component is a spacer for a glass plate using a raw material in consideration of glass surface contamination.

[Prior technical literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2012-188785

[Patent Document 2] Japanese Patent Laid-Open No. 2010-242057

[Patent Document 3] Japanese Patent Laid-Open No. 2008-208478

[Patent Document 4] Japanese Patent Laid-Open No. 2006-44674

However, the current situation is that even if a spacer is used to prevent cracking or damage to the glass plate, these conditions cannot be completely prevented. Depending on the situation, the surface of the glass plate may be cracked or damaged due to some reasons. The contamination of the surface of the plate causes the defect rate of the glass plate to increase. For example, for a glass plate used for a flat panel display, if there is little breakage, damage, or pollution on its surface, the possibility of disconnection or short circuit is increased. Therefore, it is required that the glass plate Cracks and damage caused by boards, and less contaminated spacers. In addition, since the surface of the glass plate becomes an image display surface, cleanliness and beauty are also required, and from this point, cracks, damage, and pollution must also be reduced. In addition, if the defect rate rises due to such cracks, damage, pollution, etc., it is also a problem from the viewpoint of accounting, so how to prevent the crack, damage, pollution, etc. of the glass plate surface used for flat panel displays, or How to achieve a higher yield has become a larger issue.

It is difficult to identify the cause of such cracks, damages, and contamination of glass plates, but one of the reasons has been determined to be fine foreign matter, which exists on the surface of the spacer for glass plates or from the spacers for glass plates. The surface of the paper is transferred to the surface of the glass plate.

In addition, it has been determined that one of such foreign substances is an aluminum-based solid inorganic substance.

In addition, when the glass sheet is sandwiched between the glass sheets, when the physical state of the front and back surfaces of the sheet is different, it may be necessary to consider a specific surface of the sheet and the surface of the glass sheet. contact. For example, for a glass plate for a flat panel display, in order to form a fine circuit on the surface, even if it is a trace amount of foreign matter, it is particularly avoided to adhere to it or to break or damage caused by the foreign matter. If there is more foreign material on one surface of the spacer paper than the other surface, the surface of the glass plate is cracked or damaged due to the foreign material, or the risk of the foreign material being transferred to the surface of the glass plate is increased, so it should be considered to make the foreign material The spacer paper is brought into contact with the surface of the glass plate in such a manner that the surface with fewer surfaces rather than the presence of foreign objects comes in contact with the surface of the glass plate. In this case, it is considered to sandwich two pieces of spacer paper between the glass plates, so that the surface with a small amount of foreign matter in the surface of each spacer paper faces the glass plate, but it will increase the amount of spacer paper used. The weight of the laminated body of the glass plate is increased, so it is not good in handling.

An object of the present invention is to solve the above-mentioned problems caused by the difference in the front and back states of the spacer for a glass plate. An object of the present invention is to provide a spacer for a glass plate, in which any one of the front surface and the back surface can be brought into contact with the glass plate.

Therefore, after intensive research, the present inventors have found that it is possible to provide a spacer paper for glass plates by reducing the amount of aluminum-based solid inorganic matter present on the surface of the spacer paper for glass plates, and suppressing the front side of the spacer paper and The difference in the presence ratio of the aluminum-based solid inorganic substance on the back can suppress the difference in the state of the front and back of the spacer for the glass plate, so that any one of the front and the back can contact the glass plate, thereby completing the present invention.

The first aspect of the present invention is a spacer for glass plates, which uses wood pulp as a raw material, and the existence ratio of aluminum-based solid inorganic substances on one surface is 20 per 100 m ² or less, and aluminum on one surface is The difference between the existence ratio of the solid inorganic substance and the existence ratio of the aluminum-based solid inorganic substance on the other surface is within 8 pieces / 100 m ² .

The average particle diameter of the aluminum-based solid inorganic material is preferably 20 to 300 μm.

The aluminum-based solid inorganic substance preferably contains one or more aluminum-based compounds selected from the group consisting of aluminum hydroxide, aluminum oxide, and aluminum silicate.

It is preferable that the thickness of the said spacer paper for glass plates is 20-200 micrometers.

The glass plate is preferably a glass plate for a display, more preferably a glass plate for a TFT liquid crystal display or a glass plate for an organic EL display.

A second aspect of the present invention relates to a manufacturing method, which is a method for manufacturing the above-mentioned spacer paper for glass plates, and includes at least: a slurry preparation step for preparing a slurry of wood pulp; and a sheet forming step for converting the above slurry Forming a sheet shape; a wet paper preparation step that dehydrates the sheet to form a wet paper; and a drying step that dry the wet paper to obtain the spacer paper; and performing the wet paper preparation step from both sides of the sheet Dehydration.

The above-mentioned dehydration is preferably performed by suction.

Preferably, the difference between the suction dehydration ratio on one surface of the sheet and the suction dehydration ratio on the other surface is 10% or less of the suction dehydration ratio on the other surface.

Preferably, the manufacturing method includes an additional suction step of further suctioning both sides of the spacer paper after the drying step.

The present invention also relates to a laminated body of a spacer sheet for a glass plate and a glass plate according to the first aspect of the present invention.

The present invention also relates to a method for protecting a glass plate, which includes a step of disposing a spacer for a glass plate in a first aspect of the present invention between the glass plates.

In the spacer paper for glass plates of the present invention, the amount of the aluminum-based solid inorganic substance existing on the surface is small, and the difference in the presence ratio of the aluminum-based solid inorganic materials on the front and back surfaces of the spacer paper is suppressed. The difference in the existence state of the aluminum-based solid inorganic substance on the front and back sides of the paper is suppressed. Therefore, the spacer sheet for glass plates of the present invention can be in contact with either the front or the back of the glass plate. This makes the spacer for the glass plate of the present invention excellent in operability.

In addition, the spacer paper for glass plates was originally rolled into a roll and shipped. In this rolled state, the front surface of the spacer paper is in contact with the back surface. Therefore, for example, there are fewer aluminum-based solid inorganic substances on the front surface but more on the back surface. When there is an aluminum-based solid inorganic substance in the ground, even if the front side of the spacer paper is to be brought into contact with the surface of the glass plate, the aluminum-based solid inorganic substance on the back side of the spacer paper in the rolled state will be transferred to the front side, so that the front side has The cleanliness may be reduced.

However, even if the spacer paper for glass plates of the present invention is rolled into a roll shape, it is possible to suppress the transfer of the aluminum-based solid inorganic material from one surface of the spacer paper to the other surface, so there is no need to worry about being rolled into a roller. This leads to a decrease in the cleanability of the front surface of the spacer paper, that is, an increase in the presence ratio of the aluminum-based solid inorganic substance.

Furthermore, in the spacer paper for glass plates of the present invention, the amount of aluminum-based solid inorganic substances present on the surface is small. Therefore, even if the spacer paper is in contact with the surface of the glass plate, it is possible to reduce or prevent cracks, damage, Pollution, etc., can effectively suppress or even prevent the transfer of aluminum-based solid inorganic substances from the spacer paper to the surface of the glass plate, so the production yield of the glass plate for flat panel displays can be improved in particular. In addition, the glass spacer of the present invention can minimize the occurrence of cracks, damage, and contamination of the glass plate. This makes it possible to prevent disconnection of the circuit of the color film or the like in the manufacturing process of the TFT liquid crystal display or the like.

The first aspect of the present invention is a spacer for glass plates, which uses wood pulp as a raw material, and the existence ratio of aluminum-based solid inorganic substances on one surface is 20 per 100 m ² or less, and aluminum on one surface is The difference between the existence ratio of the solid inorganic substance and the existence ratio of the aluminum-based solid inorganic substance on the other surface is within 8 pieces / 100 m ² .

In the spacer for a glass plate of the present invention, the presence ratio of the aluminum-based solid inorganic substance on one surface is limited to 20 pieces / 100 m ² or less. The number of aluminum-based solid inorganic substances existing on one surface of the above-mentioned spacer for glass plate is preferably 15 / 100m ² or less, more preferably 10 / 100m ² or less, and even more preferably 5 / 100m ² or less, still further more preferably 3 / 100m ² or less, and further more preferably 1 / 100m ² or less, and particularly preferably 0.8 / 100m ² or less.

In the spacer for a glass plate of the present invention, the difference between the presence ratio of the aluminum-based solid inorganic substance on one surface and the presence ratio of the aluminum-based solid inorganic substance on the other surface is within 8 pieces / 100 m ² , preferably Within 5 / 100m ² , more preferably within 3 / 100m ² , more preferably within 1 / 100m ² , and even more preferably within 0.5 / 100m ² . That is, in the spacer for a glass plate of the present invention, it is preferable that the proportion of the aluminum-based solid inorganic substance on one surface does not fall within the above specific range based on the proportion of the aluminum-based solid inorganic substance on the other surface. Large changes. Here, the "existence ratio" refers to the number of aluminum-based solid inorganic substances per unit area of the surface of the spacer paper. For example, multiple portions of the surface of the spacer paper for glass plates can be enlarged and observed by using an electron microscope, and The number of aluminum-based solid inorganic substances observed at this site is determined by averaging. Or as another method, the surface of a predetermined area of the spacer for the glass plate is sufficiently washed with water or an acidic solution or an alkaline solution, and the aluminum solid inorganic substances falling off are counted, thereby determining the aluminum solid inorganic Existence of matter.

In the spacer paper for glass plates of the present invention, the amount of the aluminum-based solid inorganic substance existing on the surface is small, and it is possible to suppress the variation in the proportion of the aluminum-based solid inorganic substance on the front and back of the spacer paper. The physical state of the front and back of the spacer for glass plates is suppressed. Therefore, in the spacer paper for a glass plate of the present invention, the amount of the aluminum-based solid inorganic substance on the surface is not significantly different from the front surface and the back surface of the spacer paper. Therefore, in the spacer for a glass plate of the present invention, any one of the front surface and the back surface can be in contact with the glass plate.

The aluminum-based solid inorganic substance contains an aluminum element and is in a solid state. The "solid" as used herein refers to a state of being solid at normal pressure (1 atmosphere) and at a normal temperature (25 ° C). Therefore, the melting point of the aluminum-based solid inorganic substance exceeds 25 ° C, preferably 50 ° C or more, more preferably 80 ° C or more, and even more preferably 100 ° C or more.

The Mohs hardness of the aluminum-based solid inorganic material is preferably 4 or more. The so-called Mohs hardness refers to a hardness index of 10, which is obtained by rubbing the corresponding standard substance with the substance to be measured, and comparing the hardness of the standard substance with respect to whether there is damage. Value. The reference materials range from soft (Mohs hardness 1) to hard (Mohs hardness 10) in order: 1: talc, 2: gypsum, 3: calcite, 4: fluorite, 5: apatite, 6: feldspar , 7: Quartz, 8: Topaz, 9: Corundum, 10: Diamond. The method for measuring Mohs hardness is to prepare two plates with smooth surfaces and known Mohs hardness, sandwich the aluminum-based solid inorganic substance to be measured between the two plates, and rub the two plates against each other to check the surface of the plate. Is there any damage?

The type of the aluminum-based solid inorganic substance is not limited, but it is preferable to include one or more aluminum-based compounds selected from the group consisting of aluminum hydroxide, aluminum oxide, and aluminum silicate.

In the present invention, the volume of aluminum-based solid inorganic substance is preferably controlled to less than 0.03mm ^3, more preferably less than 0.01mm ^3, and further more preferably 0.001mm ^3, and further again more preferably 0.0001mm ^3. An aluminum-based solid inorganic substance is different from a dirt, and it exists as a three-dimensional object on the surface or inside of the spacer paper, causing a problem. In particular, if the size of the aluminum-based solid inorganic material is 0.03 mm ³ or more, when the glass spacer is used, there is a high possibility that the aluminum-based solid inorganic material contacts the surface of the glass plate and leaves damage or breakage. For example, when glass spacer paper and glass plate are laminated, the aluminum-based solid inorganic substance existing on the surface of the spacer paper may be squeezed due to the weight of the glass plate, but if the size of the aluminum-based solid inorganic substance is small, Even if pressed, aluminum-based solid inorganic substances are buried in the paper of the spacer paper, so the possibility of damage to the surface of the glass plate is reduced. Furthermore, as described above, the aluminum-based solid inorganic substance is a three-dimensional object. Therefore, especially when the projection area is small but has a certain height, it may be scratched when the glass or glass spacer is moved, leaving the naked eye. Visible damage. On the contrary, when the height is low but the projection area is large, the surface of the glass plate may be damaged, so it is still not good.

The particle size of the aluminum-based solid inorganic material is preferably 20 μm or more. Specifically, the average particle diameter of the spherical volume equivalent diameter of the aluminum-based solid inorganic material is preferably 20 to 300 μm, more preferably 20 to 200 μm, still more preferably 20 to 150 μm, and still more preferably 20 to 100 μm. , Particularly preferably 20 to 50 μm. The equivalent diameter of a sphere volume refers to the diameter of the sphere when the particles of an aluminum-based solid inorganic substance are converted into spheres of the same volume, and can be measured by a laser diffraction method or the like.

The wood pulp used in the present invention is conifer bleached kraft pulp (NBKP), broadleaf bleached kraft pulp (LBKP), conifer bleached sulfite pulp (NBSP), broadleaf bleached sulfite pulp (LBSP), thermomechanical pulp (TMP) and other wood pulp used alone or mixed. The wood pulp can be used as the main body, and non-wood pulp such as hemp, bamboo, straw, kenaf, tadpole, linden, or cotton, modified pulp such as cationized pulp, mercerized pulp, etc. Synthetic or chemical fibers such as nylon, nylon, acrylic, polyester, or microfibrillated pulp are added or mixed separately. However, if the pulp contains a large amount of resin components, this resin component may cause bad influences such as contaminating the surface of the glass plate. Therefore, it is preferable to use chemical pulp with less resin components alone, such as conifer bleached kraft pulp. . In addition, high-yield pulp such as wood pulp is not preferable because it contains a large amount of resin components. In addition, if synthetic fibers and chemical fibers are mixed, the cuttability is improved, and the workability when the spacer is formed into a lithography is improved. However, in terms of waste disposal, the recyclability is deteriorated, so it is necessary to pay attention.

In addition, as long as the performance of the present invention is not impaired, if necessary, an adhesive, a mildew-proofing agent, various paper-making fillers, a wet paper strength enhancer, and a dry paper strength enhancer may be added to the papermaking fibers mainly composed of the above wood pulp. Agents, sizing agents, colorants, fixatives, yield improvers, viscosity control agents, etc. Next, the well-known existing fourdrinier papermaking machines, rotary screen papermaking machines, short-net papermaking machines, and longnets can be used. Combined with a rotary screen papermaking machine, etc. In addition, care must be taken when adding these chemicals to prevent insects and dirt from being mixed in.

The thickness of the spacer paper for a glass plate of the present invention is preferably 20 to 200 μm, more preferably 30 to 150 μm, and even more preferably 40 to 200 μm. In this way, by making a relatively thin spacer paper, it is possible to further suppress the difference in the physical state of the front surface and the back surface of the spacer paper.

The basis weight of the spacer for a glass plate of the present invention is preferably 20 to 80 g / m ² , more preferably 25 to 70 g / m ² , and even more preferably 30 to 60 g / m ² .

The moisture content of the spacer for glass plates of the present invention 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 spacer paper for glass plates itself is likely to be electrostatically charged, and a static electricity-induced adhesion phenomenon may occur between the spacer and the glass plate, which is not preferable. In addition, if the water content exceeds 10% by mass, there is a possibility that the adhesion to the glass plate caused by excessive water content or the dimensional stability caused by reduced water content during use may deteriorate.

Regarding the surface resistance value of the spacer for the glass plate of the present invention (based on JIS K 6911 1995), the spacer was subjected to humidity conditioning at a temperature of 23 ° C. and a relative humidity of 50% for more than 24 hours, and then under the same conditions In the next measurement, it is preferably in the range of 1 × 10 ⁸ to 1 × 10 ¹³ Ω, more preferably in the range of 5 × 10 ⁸ to 5 × 10 ¹² Ω, and even more preferably 1 × 10 ⁹ to 1 × 10 Within ¹² Ω. When the surface resistance value is less than 1 × 10 ⁸ Ω, the adhesiveness between the glass plate and the spacer paper is reduced, so that the operability may be deteriorated. Furthermore, a surface resistance value of less than 1 × 10 ⁸ Ω means that water or a conductive substance (for example, a surfactant) is added more than necessary. Excessive moisture may have a bad effect on the dimensional stability of the spacers for glass plates. In addition, most of the conductive materials are organic materials, so there is a problem such that these materials are transferred to the surface of the glass plate in contact and cause pollution. Yu. On the other hand, if the surface resistance value of the spacer paper for glass plates becomes a high resistance value exceeding 1 × 10 ¹³ Ω, static electricity is liable to be carried out, and the spacer paper may be in close contact with the surface of the glass plate in contact, which may significantly impede operability. Examples of a method for adjusting the surface resistance value within a desired range include moisture adjustment by, for example, drying.

The spacer paper for glass plates of the present invention may also include short fibers having a fiber length of 200 μm or less, but the short fibers may cause foreign matter to be pulled out. Therefore, the content of the short fibers is preferably relative to the absolute dry quality of the spacer paper. 4.5% by weight or less, more preferably 4.0% by weight or less, still more preferably 3.5% by weight or less, even more preferably 3.0% by weight or less. Here, the "fiber length" means an average fiber length. Therefore, all the short fibers having a fiber length of 200 μm or less have a fiber length of 200 μm or less. In other words, the maximum fiber length of the short fibers is 200 μm or less. Here, the fiber length refers to the length of the fiber when the fiber is stretched straight.

The average fiber diameter of the short fibers is preferably 10 μm to 50 μm, more preferably 12 μm to 40 μm, and even more preferably 15 μm to 30 μm.

In addition, the "average fiber diameter" herein refers to magnifying observation of a plurality of parts of the surface of the spacer paper for glass plates using an electron microscope, randomly screening a predetermined number of fibers from each electron microscope image, and measuring the selected fibers And the average fiber diameter obtained by averaging them. The number of fibers to be screened is 100 or more, preferably 150 or more, more preferably 200 or more, and even more preferably 300 or more.

The amount of the short fibers on the surface of the spacer for the glass plate of the present invention is preferably 50 to 600 / cm ² , more preferably 60 to 500 / cm ² , and even more preferably 70 to 400 / cm ² . If the amount of short fibers is relatively small, the amount of foreign matter drawn by the short fibers can be reduced.

In the spacer for a glass plate of the present invention, the difference between the amount of the short fibers on one surface and the amount of the short fibers on the other surface is preferably 15% or less of the amount of the short fibers on the other surface, more It is preferably at most 12%, and even more preferably at most 10%. That is, in the spacer for glass plates of the present invention, it is preferred that the amount of short fibers present on one surface does not vary greatly to a degree within the above-mentioned specific range depending on the amount of short fibers present on the other surface. Here, the "presence amount" refers to the number of the short fibers on the surface of the spacer paper. For example, an electron microscope can be used to magnify and observe a plurality of parts of the surface of the spacer sheet for a glass plate, and The number of short fibers is determined by averaging. In addition, short fibers having a size of 200 μm or less can be determined by screening short fibers having a thickness of 200 μm or less from fibers dropped by rubbing the front side of the spacer paper downward with a predetermined area by a sheet or the like. Furthermore, by dividing the spacer paper into two parts along the center of the thickness direction to form two very thin papers, each paper can be slurried and the number of short fibers of 200 μm or less in the slurry can be determined. Or as another method, the surface of the spacer for the glass plate is sufficiently washed with water, and the dropped fibers are supplied to a fiber length measuring machine, thereby determining the amount of short fibers present.

The spacer paper for glass plates of this invention can be manufactured based on a usual method, such as a papermaking method.

The second aspect of the present invention is a manufacturing method, which is a method for manufacturing spacer paper for glass plates, and includes at least: a slurry preparation step for preparing a slurry of wood pulp; and a sheet forming step for forming the above slurry into Flakes; a wet paper preparation step that dehydrates the sheet to form a wet paper; and a drying step that dry the wet paper to obtain the spacer paper; and performing the wet paper preparation step from both sides of the sheet-like slurry Dehydration.

In the above pulp preparation step, the pulp of wood pulp can be prepared by a previously known method. For example, in the above-mentioned slurry preparation step, the cellulose fibers constituting the wood pulp are deagglomerated and used as an aqueous suspension to prepare a slurry.

In addition, as long as the performance of the present invention is not impaired, if necessary, an adhesive, an antifungal agent, an antifoaming agent, a filler, a wet paper strength enhancer, a dry paper strength enhancer, a sizing agent, Colorants, fixatives, yield improvers, viscosity control agents, etc. In addition, care must be taken when adding these chemicals to prevent insects, dirt, etc. from being mixed in.

The reason why foreign matter such as aluminum-based solid inorganic substances are mixed in the glass spacer paper is that it is mixed in the papermaking step. For example, the case where it mixes in papermaking chemicals, or the case where the raw material of various apparatuses falls off and mixes in paper, etc. are mentioned. As a method for removing foreign matter in such a papermaking step, a dust removal device such as a cleaner or a sieve device, and other cleaning devices can be used. In the present invention, known methods can be used for the removal methods. For example, centrifugal cleaners, special weight cleaners, medium concentration cleaners, lightweight cleaners, porous screens, slot screens, vibrating screens, flat screens, And other washing machines. In addition, there is a possibility that foreign matter may be mixed into the pipe of paper or white water, so it is better to keep the pipe and the like clean at all times.

In addition, it is also possible to adjust the hot-water extraction pH of glass spacer paper to reduce or even avoid the precipitation of aluminum-based solid inorganic substances.

In the glass spacer of the present invention, the hot-water extraction pH measured in accordance with JIS P-8133 is preferably 3.5 to 6.0. According to the spacer paper for glass plates designed in this range, the aluminum-based solid inorganic material is significantly reduced. On the other hand, if the pH of the hot water extraction exceeds 6.0, the aluminum-based solid inorganic material increases. As a result, problems are caused when the panel is formed. Increasing tendency. It is speculated that the stable state of aluminum is affected by the change of the pH of the aqueous solution. Aluminum exists as Al ³⁺ in an acidic region, but becomes aluminum hydroxide in a neutral region, and is easily precipitated as a solid. In consideration of this point, as a result of diligent research, the presence of the aluminum-based inorganic solids in the spacer paper for glass plates of the present invention can be suppressed by designing the hot water extraction pH of the spacer paper for glass plates within the above range. Furthermore, in the case where spacer paper for glass plates with a hot water extraction pH of less than 3.5 is designed, the papermaking conditions become extremely acidic regions, which causes problems such as deterioration in the quality of spacer paper.

The method for setting the hot-water extraction pH of the spacer paper for glass plates to 3.5 to 6.0 is not particularly limited. Various acidic or alkaline materials can be used. For example, the sulfuric acid can be adjusted during the papermaking process of the spacer paper for glass plates. Added amount.

In the case where the spacer paper for glass plates is paper-made in such a way that the hot-water extraction pH is in the above range, aluminum in white water exists as aluminum ions in the acidic region, so it is difficult to become a solid foreign matter in the spacer paper without precipitating. On the other hand, if white water is a neutral region, it will be easily precipitated as aluminum hydroxide or aluminum oxide. In addition, during the precipitation of aluminum hydroxide, inorganic ions such as silicic acid ions in water are further fused to form a larger volume of aluminum silicate and the like. These cause the solid foreign matter in the spacer paper. Therefore, examples of the aluminum-based solid inorganic substance include aluminum hydroxide, aluminum oxide, and aluminum silicate.

In the present invention, the hot-water extraction pH of the spacer paper for glass plates is preferably set to a range of 3.5 to 5.5, more preferably a range of 3.5 to 5.0, and even more preferably a range of 3.5 to 4.9. The reason is that in the case where the pH of hot-water extraction exceeds 5.0 (especially the pH of hot-water extraction exceeds 5.5), when a very high-definition display used in a mobile terminal or the like is required, it is mainly due to the trace amount transferred to glass The disconnected portion of the color film produced by the aluminum-based inorganic substance is more conspicuous, and it is judged that there is a higher risk of poor quality.

In the preparation of the above-mentioned pulp, the effect of increasing the strength between paper layers can be expected if wood pulp is beaten. However, if the microfibers are increased by beating, there is a risk that foreign matter is pulled out or paper powder is generated as a spacer paper during use, so it is not good to increase the beating degree more than necessary. The preferred beating degree in the present invention is 300-650mlc.s.f.

In the sheet forming step of forming the slurry into a sheet, the sheet can be formed by a conventionally known method. For example, by ejecting the above-mentioned slurry onto a flat wire (for example, a Fourdrinier papermaking machine), or by using a wire wound into a cylindrical drum to take a piece from the slurry (for example, a Fourdrinier papermaking machine) Available tablets.

In a second aspect of the present invention, in the wet paper preparation step of dehydrating the sheet to form a wet paper, dehydration is performed from both sides of the sheet. Thereby, the aluminum-based solid inorganic substance contained in the sheet can be effectively removed from both sides of the sheet. In addition, the difference between the existing ratio of the aluminum-based solid inorganic substance on one surface of the spacer for the glass plate obtained by the second aspect of the present invention and the existing ratio of the aluminum-based solid inorganic substance on the other surface can be Less than 8 / 100m ² .

The method of dehydration is arbitrary, and a conventionally known method can be used. For example, dehydration can be performed by pressing the above-mentioned sheet with a roller. However, in order to effectively remove the aluminum-based solid inorganic substance, it is preferable to perform the above-mentioned dehydration by suction.

The step of dewatering from both sides of the sheet can also be performed, for example, by sucking the sheet in the vertical direction by a suction device in a state where the sheet extending from the net in the horizontal direction is clamped from above and below, but due to the influence of gravity , There will be a difference between the suction force in the upward direction and the suction force in the downward direction, so that the sheet surface on the side being sucked upwards will remain compared to the sheet surface on the side being sucked downwards. Since aluminum is a solid inorganic substance, it is preferred to use a net to stretch the sheet extending in the vertical direction and suck the sheet in the left and right direction to perform dehydration. In this case, it is preferable to maintain the moving direction of the wet paper in a vertical direction or an inclination range within 30 ° from the vertical direction.

It is preferable that the difference between the above-mentioned suction dehydration ratio (dehydration rate) on one surface of the above-mentioned sheet and the above-mentioned suction dehydration ratio (dehydration rate) of the other surface is preferably the above-mentioned suction dehydration ratio (dehydration) of the other surface Rate) is less than 10%. That is, in the manufacturing method of the spacer for glass plates of this invention, it is preferable to perform suction from both surfaces of a sheet | seat with substantially the same suction force.

The above-mentioned sheet forming step and wet paper preparation step may be performed individually using different devices, or may be continuously or partially overlapped in the same device. For example, at the same time, the slurry can be placed on a silk (web) in a wire section of a papermaking machine, and the sheet can be pelletized and dehydrated to form a wet paper.

In the above-mentioned drying step, the above-mentioned spacer paper can be obtained by drying the wet paper by a conventionally known method using a drying drum or the like.

In order to further remove the aluminum-based solid inorganic substance that may remain on the surface of the spacer paper, in the method for producing a spacer paper for a glass plate of the present invention, it is preferable to further add suction to both sides of the spacer paper after the drying step described above. Aspiration step.

In addition, during the papermaking of the spacer for glass plate and / or after papermaking, processing such as calendering, supercalendering, soft calendering, and embossing may be performed. Through processing, surface properties and thickness can be adjusted.

According to the manufacturing method of the 2nd aspect of this invention, the spacer paper for glass plates of the 1st aspect of this invention can be manufactured efficiently.

The spacer for glass plates of the present invention can be used by being inserted between glass plates. For example, it is typical to insert the above-mentioned spacer for glass plates one by one between a plurality of glass plates to form a laminate as a whole, and use the laminate as a storage and transportation object. Moreover, the spacer for glass plates of this invention can also be used for packaging a glass plate alone or the said laminated body. Therefore, the present invention has an aspect of a method for protecting a glass plate, which includes a step of disposing (particularly inserting) the above-mentioned spacer for a glass plate between glass plates.

The glass plate is not particularly limited, but a glass plate for a flat panel display such as a plasma display panel, a liquid crystal display panel (especially a TFT liquid crystal display panel), or an organic EL display panel is preferred. Fine electrodes, partition walls, etc. are formed on the surface of the glass plate for a flat panel display. However, by using the spacer paper for a glass plate of the present invention, the problem of cracking or damage of the glass plate, and the transfer of foreign objects to the glass plate can be suppressed. The problem is that even if fine electrodes, partition walls, etc. are formed on the surface of the glass plate, defects caused by the foreign matter can be suppressed or even avoided, and as a result, defects of the display can be suppressed or even avoided.

Along with the increase in the size of the display, the size and weight of the glass plate for a flat panel display have increased. However, the spacer paper for a glass plate of the present invention can particularly well protect the surface of such a large or heavy glass plate. Especially in the spacer for the glass plate of the present invention, the content of the aluminum-based solid inorganic substance is extremely small, so even if it is squeezed by the heavy-weight glass plate, it can reduce or even prevent the surface of the glass plate from cracking or damaging. Prevent foreign matter from being transferred to the surface of the glass plate, so in particular, the production yield of the glass plate for a flat panel display can be improved. Therefore, the spacer paper for glass plates of this invention can be used suitably for the glass plate for flat panel displays.

[Example]

Hereinafter, the present invention will be described more specifically using examples and comparative examples, but the scope of the present invention is not limited to the examples.

[Determination of aluminum-based solid inorganic substances]

Prepare 4 pieces of samples obtained by cutting a glass plate spacer paper at a size of 30 cm × 100 cm, and hang them (in a vertical manner when viewed from the ground). One side of the spacer paper was cleaned from above with 150 mL of ultrapure water. The cleaned water was collected and filtered with a membrane filter (pore size 10 μm). The residue was observed with an electron microscope, and foreign matter having a particle diameter of 20 μm or more was used for EDS analysis to determine the number of aluminum-based solid inorganic substances. In addition, when there are countless foreign matters, 50 foreign matters that are considered to be inorganic solid matters are observed, and the number ratio of aluminum-based solid inorganic matters is calculated.

[Transfer test method to glass plate (conveyance test)]

Laminate the glass mounting surface on the aluminum L-shaped stand at a 75-degree angle with polyurethane, facing the mounting surface for placing the glass plate in the vertical direction, and the rear end from the mounting surface. Insert the spacer for the glass plate between the 120 glass plates with a size of 680mm × 880mm × 0.7mm and each glass plate extending from the back surface extending in the vertical direction, and erect it in parallel with the back surface. The belt-shaped conveyor belt of the stand is erected from the rear end portion to the back surface over the entire circumference to fix the glass plate. In order to prevent dust, dirt, etc. from coming in from the outside, the entire surface of the stand set as described above is covered with packaging material. Thereafter, a transport test on the track was performed. The transportation test condition is that the test is performed at a transportation distance of 1000 km (storage in the environment of 40 ° C. × 95% RH for 5 days during transportation).

[Example 1]

To a pulp prepared by depolymerizing 100 parts by mass of coniferous bleached kraft pulp to a degree of beating of 520 mlc.sf, 0.2 parts by mass of polypropylene amidamine (trade name: Polystron1254, Arakawa Chemical Industries, Ltd.) was added to the total mass of the pulp. (Manufactured) as a paper strength enhancer to prepare a pulp slurry having a concentration of 0.4%. Furthermore, acetic acid was added to this slurry, and the pH of the pulp slurry was adjusted to 5.5. Used in a Fourdrinier papermaking machine equipped with an on top former in the wire section, and dewatered from both sides of the wet paper by the overlapped forming machine to obtain a basis weight of 50 g / m ² Spacer for glass plate.

[Example 2]

A spacer paper for a glass plate having a basis weight of 50 g / m ² was obtained by the same method as in Example 1 except that the pH of the pulp slurry was set to 4.8.

[Comparative Example 1]

A spacer paper for a glass plate having a basis weight of 50 g / m ² was obtained in the same manner as in Example 1 except that a laminating machine was not used.

[Comparative Example 2]

A spacer paper for a glass plate having a basis weight of 50 g / m ² was obtained in the same manner as in Example 1 except that the amount of acetic acid was adjusted so that the pH of the pulp slurry was 6.2.

The existence ratio of the aluminum-based solid inorganic substance on the surface of the spacer for the glass plate of the examples and comparative examples was determined. As a result, in Example 1, one surface was 10 pieces / 100m ² and the other surface was 8 pieces / 100m ² . In Example 2, one surface was 5 pieces / 100m ² , and the other surface was 1 piece / 100m ² . In Comparative Example 1, the number of the front surface was 14 pieces / 100 m ² , and the number of the other surface was 5 pieces / 100 m ² . In Comparative Example 2, one surface was 22 pieces / 100m ² , and the other surface was 15 pieces / 100m ² . In addition, the transfer test was used to confirm the transfer of the spacer paper for glass plates obtained in the examples and comparative examples to the glass plate. When an array of liquid crystal panels was formed using the glass plate using the spacer paper of Examples 1 and 2, See broken line of color film. On the other hand, when an array of liquid crystal panels was formed using a glass plate using spacer paper for glass plates of Comparative Example 1 and Comparative Example 2, disconnection of the color film was seen.

Claims (12)

A spacer for glass plates, which uses wood pulp as a raw material, and has an aluminum-based solid inorganic substance on one surface at a ratio of 20 / 100m ² or less, and an aluminum-based solid inorganic substance on one surface and another The difference in the existence ratio of the aluminum-based solid inorganic substance on one surface is within 8 pieces / 100 m ² .     The spacer for a glass plate according to claim 1, wherein an average particle diameter of the aluminum-based solid inorganic material is 20 to 300 μm.         The spacer for a glass plate according to claim 1 or 2, wherein the aluminum-based solid inorganic substance includes one or more aluminum-based compounds selected from the group consisting of aluminum hydroxide, aluminum oxide, and aluminum silicate.         The spacer for a glass plate as described in claim 3, which has a thickness of 20 to 200 μm.         The spacer for a glass plate according to any one of claims 1 to 4, wherein the glass plate is a glass plate for a display.         The spacer for a glass plate according to claim 5, wherein the display is a TFT liquid crystal display or an organic EL display.         A laminated body comprising a spacer for glass plates and a glass plate according to any one of claims 1 to 6.         A method for protecting a glass plate, comprising the step of arranging the spacer for a glass plate according to any one of claims 1 to 6 between the glass plates.         A manufacturing method, which is a method for manufacturing a spacer for a glass plate according to any one of claims 1 to 6, including at least: a pulp preparation step for preparing a pulp of wood pulp; and a sheet forming step for converting the above The slurry is formed into a sheet shape; a wet paper preparation step that dehydrates the above-mentioned sheet to form a wet paper; and a drying step that dry the above-mentioned wet paper to obtain the above-mentioned spacer paper; and in the above-mentioned wet paper preparation step, from the above-mentioned sheet, Dehydrate on both sides.         The manufacturing method according to claim 9, wherein the dehydration is performed by suction.         The manufacturing method according to claim 10, wherein a difference between the suction dehydration ratio on one surface of the sheet and the suction dehydration ratio on the other surface is a ratio of the suction dehydration ratio on the other surface 10% or less.         The manufacturing method according to claim 10 or 11, further comprising an additional suction step of further suctioning both sides of the spacer paper after the drying step.