JP6955920B2 - Glass interleaving paper - Google Patents

Description

The present invention relates to a glass interleaving paper and a method for producing the same.

In the distribution process of laminating and storing and transporting a plurality of glasses, it is common that an interleaving paper is sandwiched between the glasses for the purpose of preventing the glass from breaking, scratching the glass surface, and contaminating the glass. In recent years, as liquid crystal flat panel displays and plasma displays have become higher in definition and larger in size, countermeasures against minute scratches and contamination generated on the glass surface for displays have been required.

In order to reduce scratches caused by glass interleaving paper, for example, as a measure for preventing scratches caused by glass interleaving paper, a technique for defining the content of minerals having a predetermined Mohs hardness or higher is disclosed (Japanese Patent Laid-Open No. 2016-006240). See Gazette).

Further, as a countermeasure against contamination caused by glass interleaving paper, a technique for defining the fluorescent X-ray intensity of silicon on the surface of glass interleaving paper is disclosed in order to reduce the content of silicone oil that causes contamination (special feature). Open 2016-098468 (see).

Japanese Unexamined Patent Publication No. 2016-006240 Japanese Unexamined Patent Publication No. 2016-098468

Unlike window glass, flat glass for vehicle window glass, and the like, glass for liquid crystal panel displays has extremely fine wiring, electrodes, and the like formed on the surface of the display glass. For example, it is required to form fine wiring having a width of about 3 to 5 μm at intervals (pitch) of about 50 to 200 μm. According to the studies by the present inventors, high cleanliness and scratch quality of the display glass surface are required for the formation of such fine wiring and the like, and minute scratches and contaminants are present on the display glass surface. Even so, it becomes a factor that impairs the formation of the metal thin film (metal compound thin film) to be the wiring and the formation of patterning by etching. Therefore, suppressing the occurrence of scratches and contamination caused by the glass interleaving paper is an extremely important issue in the situation where the display becomes large.

However, in the above-mentioned prior art, no concrete measures for reducing the content of the substance causing the occurrence of scratches and contamination caused by the glass interleaving paper have been proposed. On the other hand, in order to suppress the occurrence of scratches and contamination caused by glass interleaving paper, measures such as selecting raw pulp and additives and repeating the cleaning process with existing equipment such as cleaners are recommended. It can be very costly and labor intensive.

The present invention has been made based on the above circumstances, and an object of the present invention is to provide a glass interleaving paper having an excellent effect of suppressing minute scratches and contamination caused by the glass interleaving paper for high-definition display glass. And.

The invention made to solve the above problems is based on JIS-P8151 (2004) of the glossy surface, which contains pulp fiber as a main component, one surface having a glossy surface and the other surface having a non-glossy surface. The measured print surf surface roughness is 1.0 μm or more and 10.0 μm or less, the Beck smoothness measured in accordance with JIS-P8119 (1998) is 150 seconds or more, and the above-mentioned non-glossy surface is described above. Beck smoothness is 10 seconds or less, and Japanese Industrial Standards. TAPPI No. It is a glass interleaving paper having a drip water absorption degree of 30 seconds or less specified in 32-2 (2000). Here, the "glossy surface" means a surface having gloss. "Non-glossy surface" means a surface that does not have glossiness.

Display glass is manufactured by the float method, in which the glass is floated on molten tin to make a plate, or the overflow method (fusion method), in which the molten glass overflows from both sides of the melting tank and is fused again at the bottom of the melting tank. Is common.
The display glass formed by the float method has a tin surface (bottom surface) that is in contact with tin and a non-tin surface (top surface) that is the opposite surface that is not in contact with tin. However, it becomes an electronic member mounting surface on which electronic members such as extremely fine wiring and electrodes are provided. Since the display glass is required to have high flatness, it is necessary to control the surface of the tin surface and the non-tin surface, and it is necessary to polish the surface of the display glass. The polished display glass surface has many surface hydroxyl groups, which are a major factor in adsorptivity, and exhibits a property that pollutants are easily adsorbed.

On the other hand, the display glass manufactured by the overflow method is non-contact except for air and is molded only by the surface tension. Therefore, although the display glass has a feature that the surface can be manufactured with high quality, the molten glass is cooled. Even if the surface of the display glass is slightly contaminated, crystals may precipitate in the display glass.

The glass interleaving paper is a single-gloss paper (Yankee paper) obtained by drying with a Yankee dryer, and the glass interleaving paper is provided on an electronic member mounting surface on which electronic members such as extremely fine wiring and electrodes of display glass are provided. It is used so that the glossy surfaces of the paper come into contact with each other.
On the other hand, since the glossy surface of the glass interleaving paper that comes into contact with the electronic member mounting surface of the display glass has high smoothness, it adheres to the display glass. Further, the printed surf surface roughness of the glossy surface of the glass interleaving paper is 1.0 μm or more and 10.0 μm or less, and the Beck smoothness is 150 seconds or more. By adhering the glossy surface of the glass interleaving paper to the high-definition display glass such as the above, rubbing between the glass and the glass interleaving paper in the glass transport process is suppressed. As a result, it is possible to suppress the occurrence of minute scratches and contamination of the glass interleaving paper due to rubbing between the display glass and the glass interleaving paper to the display glass surface, and for the display due to the glass interleaving paper. It is possible to reduce defects in glass performance.

On the other hand, in the glass interleaving paper, since the Beck smoothness of the non-glossy surface is 10 seconds or less, the surface of the display glass, which is the non-mounting surface of the electronic member, and the non-glossy surface side of the glass interleaving paper come into contact with each other. In this case, due to the unevenness and waviness of the surface of the non-glossy surface, the degree of close contact between the surface of the display glass, which is the non-mounting surface of the electronic member, and the non-glossy surface is low, so that the display glass is conveyed. Occasionally, an appropriate deviation occurs, and it is possible to impart a cushioning effect against impact and deviation to the glossy surface side of the glass interleaving paper that comes into contact with the surface of the display glass, which is the surface on which the electronic member of the display glass is mounted. Therefore, the effect of suppressing the occurrence of minute scratches due to the glass interleaving paper on the electronic member mounting surface of the display glass is improved.

Further, when the display glass is stored in the atmosphere, the display glass surface is contaminated due to the reaction of the display glass surface with the external atmosphere to cause deterioration accompanied by a change in the composition of the display glass surface layer. Is also said. The above-mentioned alteration is caused by an ion exchange reaction between hydrogen ions derived from water adsorbed on the surface of the display glass and ions existing in the external atmosphere. The non-mounting surface of the electronic member of the display glass to which the non-glossy surface of the glass interleaving paper comes into contact has a relatively small number of hydroxyl groups as compared with the mounting surface of the electronic member, but may be processed as compared with the mounting surface of the electronic member. Since the amount is small and the degree of exposure to the external atmosphere is high, the above-mentioned alteration may easily occur. Further, since the non-glossy surface of the glass interleaving paper has a low degree of close contact with the non-mounting surface of the electronic member of the display glass due to the unevenness and waviness on the surface, the non-glossy surface is absorbed from the external atmosphere. Moisture contained in the glass interleaving paper is absorbed by the non-mounting surface of the electronic member in contact with the non-glossy surface, and surface hydroxyl groups are further generated on the non-mounting surface of the electronic member, so that contaminants are easily adsorbed. It is inferred that it will be. From this, the inventors of the present invention have unevenness on the non-glossy side of the glass interleaving paper in contact with the polished surface in the float method and the exposed surface in the overflow method, and have a large surface area to reduce the drip water absorption to 30 seconds or less. As a result, it was found that the water-derived hydroxyl groups are absorbed by the glass interleaving paper, so that the hydroxyl groups are reduced on the glass surface, and the pollution suppressing effect on the non-mounted surface of the electronic member of the display glass can be improved.

The measurement was performed in accordance with JIS-P8251 (2003) of the glossy surface side region when the glass interleaving paper was divided into a glossy surface side region and a non-glossy surface side region at a ratio of 20:80 in the thickness direction. The ash content is preferably 0.5% or less. When the ash content is within the above range, the effect of suppressing minute scratches caused by the glass interleaving paper on the display glass can be improved.

The basis weight of the glass interleaving paper ^{is preferably 45 g / m 2} or more and 65 g / m ² or less, and the density of the glass interleaving paper is preferably 0.55 g / cm ³ or more and 0.80 g / cm ³ or less. When the basis weight is within the above range, it is possible to improve the effect of suppressing minute scratches and contamination caused by the glass interleaving paper on the display glass.

The absolute value of the difference in Clark stiffness measured in accordance with JIS-P8143 (2009) between the flow direction of the glass interleaving paper and the width direction of the paper orthogonal to the flow direction is preferably 17 or less. Here, the flow direction refers to the direction in which the paper advances when the paper is made by the paper machine, and the width direction refers to a method perpendicular to it, that is, a direction perpendicular to the direction in which the paper advances. By setting the absolute value of the difference in Clark stiffness within the above range, it is possible to prevent wrinkles from getting caught in the glass interleaving paper, creases, edge breakage, etc. during transportation of the glass assembly for display holding the glass interleaving paper. can. Further, it is possible to improve the handleability such that the glass interleaving paper is inadvertently bent or wrinkled when being handled.

According to the present invention, it is possible to provide a glass interleaving paper having an excellent effect of suppressing minute scratches and contamination caused by the glass interleaving paper for high-definition display glass.

Hereinafter, the glass interleaving paper according to the embodiment of the present invention will be described in detail.

<Glass interleaving paper>
The glass interleaving paper contains pulp fiber as a main component, and one side is a glossy surface and the other side is a non-glossy surface. The glass interleaving paper has a print surf surface roughness of 1.0 μm or more and 10.0 μm or less measured in accordance with JIS-P8151 (2004) of the glossy surface, and conforms to JIS-P8119 (1998). The Beck smoothness measured in the above is 150 seconds or more, and the Beck smoothness of the non-glossy surface is 10 seconds or less. TAPPI No. The drip water absorption degree specified in 32-2 is 30 seconds or less.

(Pulp fiber)
The pulp fiber constitutes the main component of the base paper. The principal component means the component having the highest content on a mass basis. The pulp fiber used for the glass interleaving paper is not particularly limited, but it is preferable to use a pulp fiber having a relatively low ash content. Examples of the pulp fibers include chemical pulps such as kraft pulp (KP), sulfite pulp (SP) and soda pulp (AP), semi-chemical pulps such as semi-chemical pulp (SCP) and chemiground wood pulp (CGP), and semi-chemical pulps such as Chemigrand Wood pulp (CGP). Mechanical pulp such as crushed wood pulp (GP), thermomechanical pulp (TMP, BCTMP), refiner grandwood pulp (RGP), non-wood fiber pulp made from 楮, sansho, hemp, kenaf, etc. Examples thereof include black pulp, synthetic pulp, synthetic fiber, and rayon fiber. As the pulp fiber, two or more kinds may be mixed and used, but it is more preferable to use one kind of pulp fiber.

Among these pulp fibers, it is preferable to use only hardwood kraft pulp from the viewpoint that it is easy to set the print surf surface roughness and the Beck smoothness of the glass interleaving paper in a good range.

(Surfactant)
It is preferable to add a surfactant to the pulp slurry from the viewpoint of facilitating the cleaning and removal of contaminants present on the display glass surface. Contamination of the display glass surface has various factors such as oil mist, dust, and transfer from packaging materials, and it is difficult to transport and store the display glass surface without causing any contamination. Therefore, in order to reduce the contamination on the surface of the display glass, it is necessary to consider a combination of a means for suppressing the occurrence of the contamination and a means for facilitating the removal of the generated contamination. The present inventors have also studied the inclusion of a surfactant in the glass interleaving paper as a device for facilitating the removal of contamination, and as a means for the silicone-based contamination which is particularly difficult to remove the contamination, the emulsifying action of silicone. It was found that it is preferable to contain a nonionic surfactant having a high content. Examples of the nonionic surfactant include ester types such as glycerin fatty acid ester, sorbitan fatty acid ester, and sucrose fatty acid ester, ether types such as fatty alcohol ethoxylate, polyoxyethylene alkyl ether, and polyoxyalkylene alkyl ether, and alkyl glycosides. Can be mentioned. Of these, silicone, which is widely used as a defoaming agent for glass interleaving paper that causes contamination, is preferably an ether-type nonionic surfactant, which has a high emulsifying action and a high decontaminating effect in cleaning treatment, and is polyoxy. The alkylene alkyl ether is more preferable.

The lower limit of the content of the surfactant in the pulp slurry with respect to the pulp fiber is preferably 0.1 kg / pulp t, more preferably 0.5 kg / pulp t, and even more preferably 1.0 kg / pulp t. On the other hand, this upper limit is preferably 5.0 g / pulp t, more preferably 4.0 kg / pulp t, and even more preferably 3.0 kg / pulp t. The "pulp t" refers to the amount added to the dried pulp fiber 1t. As described above, the inclusion of a nonionic surfactant can improve the cleaning effect of silicone-based contaminants, which are particularly difficult to remove, but the inclusion of an excess of surfactant in the glass interleaving paper makes it suitable for displays. Since it may cause glass contamination, the upper limit of the amount of the surfactant added is preferably 5.0 kg / pulp t. On the other hand, as the lower limit of the amount of the surfactant added, 0.1 kg / pulp t is preferable as the content at which the emulsifying effect of silicone can be obtained.

(Size agent)
As the sizing agent, it is preferable to use a rosin-based sizing agent. When a rosin-based sizing agent is added, it is necessary to add a fixing agent such as a sulfate band, but unlike other ASA (alkenyl succinic acid anhydride) sizing agents and AKD (alkyl ketene dimer) sizing agents, a rosin-based size is used. The agent is a sizing agent that is less likely to cause stains on paper-making or the like. In other words, the rosin-based sizing agent is a sizing agent having low contamination even when used for glass interleaving paper. Further, since the rosin-based sizing agent has a higher softening point than other sizing agents, it can be suitably used in an operation using a Yankee dryer that dries and polishes at a relatively high temperature.

Further, as described above, surface hydroxyl groups caused by water on the display glass surface have been attracting attention as a cause of contamination of the display glass surface, and water repellency to water is aimed at reducing the influence of the surface hydroxyl groups. Incorporating a sizing agent in the glass interleaving paper to ensure the above is also mentioned as a pollution control measure. According to the findings of the present inventors, although the sizing agent has been disclosed as a general description for its use as an auxiliary agent in the production of glass interleaving paper, no study example of contamination caused by the sizing agent is disclosed. Not. The inventors of the present invention have repeatedly studied the use of sizing agents as a means of controlling contamination, and found that rosin-based sizing agents are preferably used. Rosin-based sizing agents have high sizing properties and adsorptivity to pulp fibers in combination with aluminum sulfate bands, and if they are excessively contained in glass interleaving paper, they may cause contamination of the glass surface for display, but they are appropriate. It was found that the addition of an amount has a water-repellent effect and an effect of inhibiting the adsorption of pollutants on surface hydroxyl groups as compared with other synthetic sizing agents. The lower limit of the content of the sizing agent in the pulp slurry with respect to the pulp fiber is preferably 0.5 kg / pulp t, and the upper limit of the content is preferably 2.0 kg / pulp t.

(Other ingredients, etc.)
Other internal additives other than the above-mentioned surfactant and sizing agent may be added to the base paper of the glass interleaving paper, but the amount added is within a range that does not cause contamination of the glass surface for display. By adding other internal additives, the resin content in the base paper can be reduced and the adhesion of the resin content to the glass can be reduced. Examples of such an internal additive include aluminum sulfate, sulfuric acid, rosin, petroleum resin, higher fatty acid, styrene-acrylic, styrene-maleic acid, as long as the glass surface is not scratched or contaminated. Sizing agents such as alkenyl anhydride succinic acid type, alkenyl keten dimer type, alkyl keten dimer type, various paper strength enhancers such as polyacrylamide, drainage yield improver, water resistant agent such as polyamide polyamine epichlorohydrin, softener, antistatic Agents, antifoaming agents, slime control agents, pitch control agents, fillers, dyes and the like can be used.

One side of the glass interleaving paper is a glossy surface, and the other side is a non-glossy surface. In the glass interleaving paper, the glossy surface side is in close contact with the surface on which the electronic member of the glass for display used for liquid crystal panel displays, plasma displays, etc. is mounted, and the non-glossy surface side is in contact with the non-mounting surface side of the electronic member. It is installed and a plurality of display glasses are laminated. Therefore, the glass interleaving paper on the non-mounting surface of the electronic member of the display glass is easily peeled off from the display glass, and the glass interleaving paper is not displaced on the electronic member mounting surface side of the display glass, so that the scratch suppressing effect is improved. do.

(Print surf surface roughness)
The print surf surface roughness is a value measured in accordance with JIS-P8151 (2004). Print surf surface roughness is a device that determines smoothness from the amount of air flowing through it, but unlike Beck smoothness, results based on the fine irregularities on the surface of the glass interleaving paper can be obtained, so the surface roughness can be evaluated closely. ..

The lower limit of the print surf surface roughness on the glossy surface side (surface side) of the glass interleaving paper that comes into contact with the electronic member mounting surface side of the display glass is 1.0 μm, preferably 1.5 μm. 0 μm is more preferable. When the print surf surface roughness is less than 1.0 μm, the glossy surface of the glass interleaving paper that comes into contact with the electronic member mounting surface side of the display glass is excessively adhered, and contamination transfer increases. On the other hand, the upper limit is 10.0 μm, preferably 9.5 μm, and more preferably 9.0 μm. When the print surf surface roughness exceeds 10.0 μm, many uneven portions are formed on the surface of the glass interleaving paper. Therefore, in the transfer process of the display glass, the adhesion to the glass deteriorates, and scratches are likely to occur during the transfer.

(Beck smoothness)
Beck smoothness is a value measured according to JIS-P8119 (1999). Beck smoothness is a device that obtains smoothness from the amount of air flow as well as print surf surface roughness, and evaluates macro-smoothness on a relatively wide surface. In the glass interleaving paper, the so-called waviness of the surface can be evaluated by the Beck smoothness. In this way, by keeping both the evaluation values of the print surf surface roughness and the Beck smoothness within a predetermined range, it is possible to evaluate the ability to suppress scratches and contamination on a microscopic surface and a somewhat wide surface. ..

The lower limit of the Beck smoothness on the glossy surface side of the glass interleaving paper that comes into contact with the electronic member mounting surface side of the display glass is 150 seconds, preferably 155 seconds. When the Beck smoothness on the glossy surface side is less than 150 seconds, the surface of the display glass that comes into contact with the electronic member mounting surface side is likely to be displaced, and scratches and contamination are likely to be transferred. On the other hand, the upper limit is preferably 400 seconds, more preferably 300 seconds. When the Beck smoothness on the glossy surface side exceeds 400 seconds, the adhesion between the electronic member mounting surface side of the display glass and the glass interleaving paper becomes high, and stains are transferred from the glass interleaving paper to the display glass. , May cause malfunction.

The upper limit of the Beck smoothness on the non-glossy side (back side) of the glass interleaving paper is 10 seconds, preferably 9 seconds. When the non-glossy surface of the electronic member of the display glass comes into contact with the non-glossy surface of the glass interleaving paper due to the Beck smoothness on the non-glossy surface side being in the above range, when the display glass is conveyed. Appropriate deviation occurs, and a cushioning effect against impact and deviation can be imparted to the glossy surface side (surface side) that comes into contact with the electronic member mounting surface side of the display glass. Therefore, it is possible to enhance the effect of suppressing minute scratches caused by the glass interleaving paper, which is particularly required for high-definition glass for liquid crystal flat panel displays and plasma displays.

(Drip water absorption)
The water absorption of the glass interleaving paper drip is determined by Japan TAPPI No. It is expressed as the time (seconds) until it is completely absorbed by the glass interleaving paper when measured with a dropping water volume of 1 μL in accordance with 32-2 (Absorbable Paper Water Absorption Rate Test Method).

The upper limit of the drip water absorption on the non-glossy surface side of the glass interleaving paper is 30 seconds, preferably 25 seconds. When the drip water absorption on the non-glossy surface side is within the above range, the amount of water retained in the non-glossy surface of the glass interleaving paper is suppressed, and the electronic member of the display glass that comes into contact with the non-glossy surface is not mounted. It is possible to adjust that the water content of the glass interleaving paper is adsorbed on the surface. As a result, the electronic member of the display glass is not mounted. The electronic member of the display glass is not mounted due to the alteration caused by the ion exchange reaction between the hydrogen ion derived from water on the surface and the ion in the external atmosphere. Surface contamination can be suppressed.

(ash)
The ash content is a value measured in accordance with JIS-P8251 (2003). When the glass interleaving paper is divided into a glossy surface side region and the non-glossy surface side region at a ratio of 20:80 in the thickness direction, the upper limit of the ash content of the glossy surface side region is preferably 0.5%. , 0.3% is more preferable. When the ash content is within the above range, the effect of suppressing minute scratches caused by the glass interleaving paper on the display glass can be improved.

As disclosed in Patent Document 1 and JP-A-2016-191162, when a mineral having a Mohs hardness of 5 or more or a Mohs hardness of 4 or more is contained in the glass interleaving paper, it comes into contact with the glass interleaving paper. Since the Mohs hardness of the display glass is in the range of 4.5 to 6.5, it is easily inferred that the glass interleaving paper and the display glass are easily scratched by rubbing against each other. On the other hand, in the glass interleaving paper, the above minerals are discharged together with white water from the wet paper surface of the glass interleaving paper by squeezing water at the time of papermaking. Therefore, it is presumed that the content of minerals defined in Patent Document 1 and the like is substantially the amount of inorganic minerals present in the middle layer of the glass interleaving paper. Therefore, it is considered that the relationship between the content of the above minerals and the scratch suppressing effect is low. Originally, it is well known that tree tissues contain calcium and other inorganic trace elements. The tree structure also contains silica having a high Mohs hardness (Mohs hardness: 7) described in Patent Document 1, and it is difficult to remove these minerals in pulp. However, the ash content on the glossy surface side when the glass interleaving paper is divided into the glossy surface side and the non-glossy surface side in contact with the electronic member mounting surface of the display glass in the thickness direction at a ratio of 20:80 is 0.5%. It was found that the following specifications suppress invisible minute scratches.

(Basis weight)
As the lower limit of the basis weight of the glass interleaving paper, 45 g / m ² is preferable, and 50 g / m ² is more preferable. If the basis weight is ^{less than 45 g / m 2} , workability at the time of supplying interleaving paper to the display glass and packing may be deteriorated. The upper limit is preferably 65 g / m ^2. In recent years, as the size of display glass has increased, the number of display glasses to be conveyed at one time has increased for the purpose of improving transfer efficiency. If the thickness of the interleaving paper to be held between the display glasses is large, the number of display glasses to be conveyed at one time is reduced. Therefore, the glass interleaving paper is required to be lightweight as well as the effect of suppressing minute scratches and contamination caused by the glass interleaving paper on the display glass. If the basis weight of the glass interleaving paper ^{exceeds 65 g / m 2} , it is not preferable from the viewpoint of weight reduction.

(density)
As the lower limit of the density of the glass interleaving paper, 0.55 g / cm ³ is preferable, and 0.60 g / cm ³ is more preferable. If the density of the glass interleaving paper is less than the above lower limit, the strength of the glass interleaving paper may be insufficient. On the other hand, the upper limit of the density of the glass interleaving paper is 0.80 g / g from the viewpoint of suppressing the amount of water and air permeation contained in the glass interleaving paper and improving the suppleness of the glass interleaving paper having the basis weight. cm ³ is preferred. Further, from the viewpoint that the print surf surface roughness and the Beck smoothness of the glass interleaving paper can satisfy the above-mentioned ranges, the density of the glass interleaving paper is preferably within the above ranges.

The thickness of the glass interleaving paper is preferably 55 μm or more and 116 μm or less, and it is preferable to adjust the thickness in the range of 77 μm to 97 μm in terms of handleability. Paper thickness is an index related to basis weight and density, and also has an effect on Clark stiffness, so it is necessary to adjust it while considering the effect on glass surface scratches and stain resistance. Paper thickness is measured according to "Paper and Paperboard-Thickness and Density Test Method" described in JIS-P8118 (1998).

(Clark scary)
Clark stiffness is a value measured in accordance with JIS-P8143 (2009) and is an index of the rigidity of the glass interleaving paper. Since the glass interleaving paper may not be installed in a predetermined installation direction during use, the arrangement in the paper flow direction and the paper width direction may not be constant. Therefore, the fact that the absolute value of the difference in Clark stiffness between the flow direction of the glass interleaving paper and the width direction of the paper orthogonal to the flow direction is excessively large means that the glass for display holding the glass interleaving paper is aggregated. This is not preferable because wrinkles are likely to be caught in the glass interleaving paper, creases, and edge breaks are likely to occur during transportation. The clerk stiffness in the flow direction of the glass interleaving paper is preferably 40 or more and 55 or less, and the clerk stiffness in the width direction is preferably 18 or more and 35 or less.

As the upper limit of the absolute value of the difference in Clark stiffness between the flow direction of the glass interleaving paper and the width direction of the paper orthogonal to the flow direction, 17 is preferable, and 15 is more preferable. By setting the above upper limit to 17, it is possible to suppress wrinkles, creases, broken edges, etc. in the glass interleaving paper during transportation of the aggregate of display glass holding the glass interleaving paper. On the other hand, as the lower limit of the absolute value of the difference in Clark stiffness, 10 is preferable, and 14 is more preferable. By setting the lower limit to 10, it is possible to easily maintain the uprightness of the glass interleaving paper protruding from between the display glasses when the glass interleaving paper is inserted into the display glass. In particular, the findings of the inventors have found that the handleability is improved by adjusting the difference in Clark stiffness in the range of 14 to 17. By adjusting the difference in Clark stiffness in the range of 14 to 17, it is possible to improve the handling performance that allows the glass interleaving paper to be handled without inadvertently bending or wrinkling the glass interleaving paper. .. The difference in Clark stiffness can be adjusted by using the J / W ratio at the time of papermaking, a dandy roll, and a shaking device.

(Freeness)
The glass interleaving paper is made into dissociated pulp by dissociating it in accordance with the method of dissociating pulp of JIS-P8220-1 (2012), and this dissociated pulp is used as a Canadian standard freshness test of JIS-P8121-2 (2012). As the lower limit of freeness measured according to the method, 450 ml is preferable, and 470 ml is more preferable. If the freeness of the disintegrated pulp is less than 450 ml, it may be difficult for the interleaving paper for glass to keep the interleaving paper protruding from between the glasses in an upright state, so that the interleaving paper may not be grasped by the take-out device. On the other hand, the upper limit is preferably 550 ml. If the freeness exceeds 550 ml, the number of entanglements between fibers and the number of bonding points is reduced, and there is a possibility that paper breakage may easily occur in the operation.

According to the glass interleaving paper, in the glass interleaving paper inserted between the glasses in the distribution process and the manufacturing process in which a plurality of high-definition display glasses such as a liquid crystal flat panel display and a plasma display are laminated and stored and transported. It has an excellent effect of suppressing minute scratches and contamination caused by glass interleaving paper on high-definition display glass.

<Manufacturing method of glass interleaving paper>
The method for producing the glass interleaving paper is not particularly limited, and includes, for example, a step of making a pulp slurry containing pulp fiber as a main component and a surfactant and a sizing agent. Next, it is dried with a Yankee dryer, and a contact surface with the Yankee dryer is formed as a glossy surface. By the above manufacturing method, the glass interleaving paper in which a surfactant and a sizing agent are embedded in a base paper can be obtained.

The pulp fibers, surfactants and sizing agents contained in the pulp slurry are as described above.

In the above method for producing glass interleaving paper, first, the pulp slurry is dehydrated (papermaking). For the papermaking of the glass interleaving paper, known papermaking means such as a long net, a circular net, and a gap former are adopted. At the time of dehydration in the wire part, unnecessary minerals are removed and at the same time, fine fibers containing a relatively large amount of ash are also removed, so that the ash content can be reduced to 0.5% or less. Further, in order to reduce the ash content, 100% virgin pulp pulp slurry papermaking, white water being closed to eliminate the inclusion of inorganic substances, and no addition of inorganic substances are adopted.

Next, one side of the pulp (paper-made pulp) obtained by dehydrating the pulp slurry is dried by a Yankee dryer. In the glass interleaving paper, the contact surface with the Yankee dryer is formed as a glossy surface. More specifically, the glossy surface of the glass interleaving paper can be obtained by pressing the wet paper against the Yankee dryer with a so-called blanket and copying the mirror surface of the cylinder surface of the Yankee dryer onto the wet paper. Further, the non-contact surface with the Yankee dryer is formed as a non-glossy surface. On the non-glossy surface side, the print surf surface roughness and the Beck smoothness are adjusted by adjusting the pressure of the touch roll that presses the blanket material or the blanket against the Yankee dryer.

The glass interleaving paper can be manufactured using existing equipment without requiring a large amount of capital investment or complicated processes, and has minute scratches and contamination caused by the glass interleaving paper for high-definition display glass. It is possible to provide a glass interleaving paper having an excellent suppressing effect.

<Other Embodiments>
The present invention is not limited to the above embodiment, and can be implemented in various modifications and improvements in addition to the above embodiment.
The glass interleaving paper based on the present invention is different from Ryosara kraft paper, which is dried and smoothed by a multi-cylinder dryer, and is dried by a Yankee type dryer, and the surface of the glass interleaving paper has both a glossy surface and a non-glossy surface. Has sex. Then, it is used so that the glossy surface of the glass interleaving paper comes into contact with the electrode mounting surface on which the electronic element of the display glass is provided. Therefore, the glossy surface of the glass interleaving paper, which also has high flatness, adheres to the highly flat surface of the glass surface for display because of its high smoothness. As a result, it is possible to bring out the effect of improving scratches and contamination, which is a problem of the present invention, and by maintaining the adhesiveness of the glass interleaving paper to the enlarged display glass, the glass interleaving paper can be used. The paper does not fall off or wrinkle, and it has high protection against display glass. Further, the glass interleaving paper is excellent in handleability such as insertion and removal of the display glass and the glass interleaving paper, and a high handling effect can be ensured.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

The methods for measuring the physical property values of Examples and Comparative Examples are as follows.

[Print surf surface roughness (μm)]
Compliant with "Measurement method of print surf surface roughness" described in JIS-P8151 (2004) using PPS TESTER (model number: SE-115 manufactured by Lorenzen and Bettley) with soft backing and clamp pressure of 1 MPa. And measured.

[Beck smoothness (seconds)]
The measurement was performed in accordance with the "Measuring method of Beck smoothness" described in JIS-P8119 (1998).

[Drip water absorption (seconds)]
JAPAN. TAPPI No. The measurement was performed in accordance with "Paper-Water Absorption Test Method-Part 2: Dropping Method" described in 32-2. The measurement was carried out with a dropping water volume of 1 μL. The time (seconds) until it was completely absorbed by the sample was measured.

[ash(%)]
The ash content (%) of the glossy surface side region was measured when each Example and Comparative Example were divided into the glossy surface side region and the non-glossy surface side region at a ratio of 20:80 in the thickness direction. The ash content was measured according to the "ash content measuring method" described in JIS-P8251 (2003).

[Basis weight (g / m ² )]
The measurement was performed in accordance with "Paper and Paperboard-Basis Weight Measuring Method" described in JIS-P8142 (1998).

[Paper thickness (μm)]
The measurement was performed in accordance with "Paper and Paperboard-Thickness and Density Test Method" described in JIS-P8118 (1998).

[Density (g / cm ³ )]
The measurement was performed in accordance with "Test method for thickness and density" described in JIS-P8118 (1998).

[Clark stiffness ^(cm 3/100)]
The measurement was performed in accordance with the "Clark stiffness measuring method" described in JIS-P8143 (2009).

[Freeness (mL)]
The obtained glass interleaving paper is made into disintegrated pulp by disintegrating it in accordance with the pulp disintegration method of JIS-P82201 (2012), and this disintegrated pulp is used as the Canadian standard freshness of JIS-P8121-2 (2012). Measured according to the test method.

[Example 1]
(1) The following raw materials were added to 100 parts of the pulp slurry of LBKP.
Rosin-based sizing agent (Arakawa Chemical Industry Co., Ltd. "Size Pine E"): 1.35 kg / pulp t
Aluminum Sulfate as Aluminum Sulfate Band (Daimei Chemical Industry Co., Ltd.): 6.00 kg / pulp t
Fatty acid ester as a surfactant (DF6300 from Seiko PMC): 2.00 kg / pulp t
(2) This pulp slurry was made by a wire part using a long net paper machine.
(3) Next, the wire surface was made a glossy surface (surface) using a Yankee dryer to obtain the glass interleaving paper of Example 1.
(4) The physical property values of the glass interleaving paper of Example 1 are as follows.
Glossy print surf surface roughness: 5.0 μm
Beck smoothness: glossy surface 230 seconds, non-glossy surface 6 seconds Drip water absorption on non-glossy surface: 20 seconds Ash content in the glossy surface side area: 0.2 (%)
Basis weight: 60 g / m ²
Paper thickness: 85 μm
Density: 0.70 g / cm ³
Clark stiffness: flow direction 43cm ^3/100, the width direction 30 cm ^3/100
Difference between flow direction and width direction (absolute value) 13
Freeness: 530 mL (mL)

[Examples 2 to 6 and Comparative Examples 1 to 6]
The glass interleaving papers of Examples 2 to 6 and Comparative Examples 1 to 6 were obtained in the same manner as in Example 1 except that the types, contents and physical property values of the raw materials were as shown in Table 1. Further, Comparative Example 6 was dried with a multi-cylinder dryer and was not subjected to a single-gloss treatment. In addition, "-" in Table 1 below indicates that the corresponding component was not used.

[evaluation]
Each of the obtained glass interleaving papers was evaluated for scratches and contamination on the non-alkali glass for liquid crystal display by the following method. The evaluation results are shown in Table 2.

Non-alkali glass for liquid crystal display with a size of 300 x 300 mm and a thickness of 0.7 mm and 10 sheets of each glass interleaving paper are alternately laminated, and a load of 5 kg is applied to them in an environment of 50 ° C. and 80% RH. After treatment for a day and cleaning the display glass, scratches and contamination on the glass surface were evaluated.

The evaluation criteria are as follows.
(Scratches on the display glass surface)
⊚: No stains or scratches were found on the surface.
◯: Slight scratches are seen on the surface, but it is judged that there is no problem in using it.
Δ: There are a few scratches on the surface, and it is judged that there is no problem in using it.
X: There are many scratches on the surface, and it is judged that there is no problem in using it.
(Contaminated display glass surface)
⊚: No contamination was found on the surface.
◯: When the surface is illuminated with light, a slight oil film-like adhesion is observed, but it is judged that there is no problem in using it.
Δ: A slight oil film-like adhesion is observed on the surface, and it is judged that there is a problem in use.
X: Oil film-like stains are scattered on the surface.
(Handling)
⊚: Handleability is very good.
◯: Depending on the working environment conditions, the handleability may be slightly reduced, but it is judged that there is no problem in using it.
Δ: Depending on the working environment conditions, the handleability is slightly inferior, and it is judged that there is a problem in using the product.
X: Regardless of the working environment conditions, the handleability is inferior, and it is judged that there is no problem in using it.

As shown in Table 2 above, it was shown that Examples 1 to 6 are excellent in the effect of suppressing minute scratches and contamination caused by the glass interleaving paper on the high-definition display glass. In addition, Examples 1 to 6 show an effect of excellent handling suitability in a distribution process or a manufacturing process in which a plurality of glasses for flat panel displays such as a liquid crystal panel display and a plasma panel display are laminated and stored and transported. Was done.
On the other hand, Comparative Examples 1 to 6 were inferior in all of scratches and contamination on the display glass surface and handleability.

The glass interleaving paper of the present invention can be suitably used as an interleaving paper for a glass substrate or the like used for a flat panel display of a liquid crystal television, a plasma television, a smartphone, a tablet or the like.

Claims (4)

Mainly composed of pulp fiber
Contains rosin-based sizing agents, aluminum sulphate bands and surfactants
The above pulp fiber is made of hardwood kraft pulp,
The freeness of the dissociated pulp is 450 ml or more and 507 ml or less.
One side is a glossy side, the other side is a non-glossy side,
The print surf surface roughness measured according to JIS-P8151 (2004) of the glossy surface is 1.0 μm or more and 10.0 μm or less, and Beck smoothness measured according to JIS-P8119 (1998). The degree is 150 seconds or more,
The Beck smoothness of the non-glossy surface is 10 seconds or less, and JAPAN. TAPPI No. Drip water absorbency prescribed in 32-2 Ri der than 30 seconds,
When the glossy surface side region and the non-glossy surface side region are divided at a ratio of 20:80 in the thickness direction, the ash content of the glossy surface side region measured in accordance with JIS-P8251 (2003) is 0.5. % der Ru glass slip sheet below. The glass interleaving paper according to claim 1, wherein the content of the rosin-based sizing agent is 0.5 kg / pulp t or more and 2.0 kg / pulp t or less. The glass interleaving sheet according to claim 1 or 2, wherein the basis weight is 45 g / m ² or more and 65 g / m ² or less, and the density is 0.55 g / cm ³ or more and 0.80 g / cm ^{3 or less.} Claim 1 in which the absolute value of the difference in Clark stiffness measured in accordance with JIS-P8143 (2009) between the flow direction of the glass interleaving paper and the width direction of the paper orthogonal to the flow direction is 17 or less. , The glass interleaving paper according to claim 2 or claim 3.