JP5916481B2 - Glass interleaving paper and laminate - Google Patents

Description

  The present invention relates to a glass interleaving paper and a laminate in which the glass interleaving paper and the glass plate are alternately laminated.

  In the distribution process of stacking and storing and transporting multiple glass plates for flat panel displays, etc., in order to prevent cracks and scratches due to contact between the glass plates and the occurrence of dirt on the glass plate surface, It is common practice to sandwich paper.

  In recent years, glass substrates for liquid crystal panels and the like have been enlarged to sizes such as 2,200 × 2,500 mm and 2,800 × 3,200 mm, and with the increase in size of this glass plate, the size of the slip sheet has also increased. ing. On the other hand, a certain uprightness (rigidity) is required for the interleaving paper in consideration of handling properties when inserted between the glass plates. In order to ensure such uprightness, it is necessary to increase the rigidity as compared with the conventional case in accordance with the increase in size of the slip sheet as described above.

  Therefore, a slip sheet using pulp fibers having a specific range of average fiber length, average fiber width, and Runkel ratio has been proposed as a glass slip sheet that can cope with an increase in size and has excellent rigidity (Japanese Patent Laid-Open No. 2008-2009). 266862). However, in the method of limiting the quality of the pulp fiber in this way, it is necessary to limit the tree species, and it is difficult to adjust the pulp, and when adjusting the average fiber length in a specific range by mixing multiple types of pulp The desired rigidity may not be exhibited. Moreover, since the density is low, it is easy to absorb moisture, and deformation may occur depending on changes in the use environment and workability may be reduced.

JP 2008-266862 A

  The present invention has been made on the basis of the circumstances as described above, and does not require strict adjustments such as basis weight and raw pulp species, has good uprightness corresponding to an increase in size, It aims at providing the glass interleaving paper which also has the stability which is hard to deform | transform by a humidity change, the laminated body using the same, and the manufacturing method of glass interleaving paper.

The invention made to solve the above problems is
A glass interleaving paper obtained by papermaking a raw material mainly composed of pulp fiber,
The disaggregated pulp contains short fibers having a fiber length of less than 1.2 mm,
The content of the short fibers in the disaggregated pulp is 40% by mass or more,
The ratio of the other surface side content to the one surface side content of the short fibers is 0.61 or more and 0.92 or less.

  The glass interleaving paper is made from a raw material mainly composed of pulp fibers, and contains a certain amount of short fibers in the disaggregated pulp, and further the paper making so that the content of short fibers on the other side is smaller than that on one side. By doing so, it is possible to stably develop a curl having high curl stability against humidity change. Therefore, the glass interleaving paper has good uprightness in the axial direction of the curl, in other words, the apparent rigidity is high. In addition, by setting the content ratio of the short fibers on one side and the other side to the above range, the degree of curling can be controlled within a predetermined range while improving the stability against curling humidity change. In addition to the uprightness and stability, the glass interleaving paper can also be handled.

  It is preferable that the freeness of the pulp from which the glass interleaving paper is disaggregated is 400 ml or more and 650 ml or less, and the fibrillation rate is 2.5% or more and 4.5% or less. As described above, when the freeness and the fibrillation rate of the pulp are set within the above ranges and the leveling is adjusted to the above range by performing the flattening treatment, the bonding force and the gap between the fibers can be controlled within the predetermined ranges. In paper, the uprightness and the stability of the curl against humidity change can be further enhanced.

  The disaggregated pulp includes softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP), and the mass ratio of NBKP to LBKP is preferably from 2:98 to 20:80. As described above, the fiber length distribution is obtained by using a pulp fiber mainly composed of LBKP and mixed with NBKP in which the mass ratio is within the above range as a raw material, and performing a flattening treatment to adjust the tension within the above range. Can be controlled within a predetermined range, it becomes easy to develop the structural curl described later, and in the glass interleaving paper, the uprightness and the stability of the curl against humidity change can be further enhanced.

As described above, in the disaggregated pulp, the proportion of short fibers is 40% by mass or more, the freeness is 400 ml or more and 650 ml or less, the fibrillation rate is 2.5% or more and 4.5% or less, and the mass ratio of NBKP and LBKP By making paper using, for example, a long-mesh system using pulp fibers so that the ratio becomes 2:98 or more and 20:80 or less, and adjusting the content ratio between one side of the short fibers and the other side, the fibers The curl with the non-wire contact surface (one surface side) outside is controlled after the bonding force and the gap between them are controlled within a predetermined range, so that the stability of the curl against humidity change can be particularly enhanced.

  The glass interleaving paper has an average curl height at four corners of 5 mm or more and 20 mm or less when cut into a square of 300 mm square with the paper making direction as one side, and the ratio of the tensile strength in the transverse direction to the tensile strength in the longitudinal direction is It is preferable that it is 0.40 or more and 0.85 or less. Thus, the said glass interleaving paper can be equipped with higher uprightness by making average curl height into the said range. In addition to this, by adjusting the orientation of the fibers in the longitudinal direction and the transverse direction, and adjusting the ratio of the tensile strength in the longitudinal direction to the tensile strength in the transverse direction (Y / T ratio) in the above range, the glass In the interleaving paper, the curl direction can be made uniform to further enhance the uprightness and to provide the curl stability against humidity change.

  The present invention relates to a glass interleaving paper having uprightness due to a curl that is stable against changes in humidity. Therefore, the fiber length distribution is controlled within a predetermined range so that a stable curl is obtained, the freeness of the disaggregated pulp is 400 ml or more and 650 ml or less, the fibrillation rate is 2.5% or more and 4.5% or less, NBKP and LBKP It is preferable to control the bonding strength between the fibers and the gap to a predetermined range by setting the mass ratio to 2:98 or more and 20:80 or less, but in addition to this, the ratio of the tensile strength and the tensile strength in the transverse direction By making the direction of curl uniform within the above range, it is possible to prevent curling change due to moisture absorption, and to impart high stability of curling to humidity change.

  The laminate of the present invention is formed by alternately laminating glass plates and the glass interleaving paper. According to the said laminated body, the glass plate is protected by the said glass interleaving paper, and it is excellent in workability | operativity, such as insertion and taking-out of a glass plate and glass interleaving paper.

  Here, “one surface side” means a portion having a thickness of about 50% from one surface in the thickness of the entire glass interleaving paper, and “the other surface side” means the entire glass interleaving paper. It means a portion having a thickness of about 50% from the other surface in thickness.

  The “fiber length” means a mass weighted average fiber length, and is a value measured according to a fiber length measurement method by an optical automatic analysis method described in JIS-P8226 (2006). “Short fiber content” means a value obtained by dividing the total mass of short fibers by the total mass of pulp fibers. “Freeness” refers to a value obtained by measuring disaggregated pulp obtained by disaggregating glass interleaving paper according to JIS-P8220 (1998) according to the Canadian standard freeness test method described in JIS-P8121 (1995). “Fibrilization rate” refers to the fiber lab. Of the disaggregated pulp obtained by disaggregating the glass interleaving paper according to JIS-P8220 (1998). The value measured using (Kajaani). The “average curl height” is the average of the four corners measured after placing the glass interleaving paper in an environment of temperature 23 ° C. and humidity 50% for 1 hour, and then placing it on a flat surface so that the convex side is in contact. Say height. “Tensile strength” refers to a value measured according to the tensile property test method described in JIS-P8113 (2006).

  As described above, the glass interleaving paper of the present invention has good uprightness and curls are not easily deformed by changes in humidity. Therefore, according to the present invention, it is possible to provide a glass interleaving paper that can sufficiently cope with an enlarged glass substrate.

  Hereinafter, embodiments of the glass interleaving paper and the laminate of the present invention will be described in detail.

<Glass interleaving paper>
The glass interleaving paper contains pulp fibers as a main raw material, the disaggregated pulp contains short fibers having a fiber length of less than 1.2 mm, and the content of the short fibers in the disaggregated pulp is 40% by mass or more. In addition, the ratio of the content ratio of the other surface side to the content ratio of one surface side of the short fiber is 0.61 or more and 0.92 or less. In the glass interleaving paper, curling with one surface side as an inner surface stably develops. Therefore, the glass interleaving paper has good uprightness in the axial direction of the curl, that is, the apparent rigidity is high. Further, since it has resistance to a shape change due to a change in humidity, the curl is highly stable.

  Here, the relationship between paper obtained by paper making and curl will be described. “Paper” produced by a paper machine has a tendency for fibers to be arranged unevenly, and anisotropy appears in the fiber orientation and the density of fibers that are arranged. Curling has been found to be closely related to the fiber orientation and density, and the fiber orientation and density control technology is an elemental technology for suppressing curling. In particular, the curling of “paper” is said to be the main factor for the occurrence of curling and the factor for determining the size of curling because of the difference in fiber orientation, fiber density, and degree of dryness. Originally, curling causes paper feeding troubles in the printing press, and therefore, it is common to make paper so as not to cause curling. However, in the glass interleaving paper, by making paper so that the ratio of the short fibers changes between one side and the other side and intentionally expressing the curl shape, particularly as a large-sized glass interleaving paper It has been found that even if it is used, it has good uprightness and is excellent in curling stability against changes in humidity.

  The glass interleaving paper of the present invention can be used as a large-sized glass interleaving paper in particular by making paper so that the fiber density changes on one side and the other side and intentionally expressing the curl shape. It is a glass interleaving paper that has good uprightness and has high curl stability against changes in humidity. Such a glass interleaving paper can be obtained, for example, by making a paper by a long net system using a long net paper machine having a long dewatering zone and performing single-side dewatering. By adjusting the J / W ratio and slicing lip using a long web paper machine, the short fibers fall off on the other side in contact with the long mesh wire, and on the other side that does not contact the long mesh wire. A paper containing a lot of short fibers can be obtained.

Further, by drying the dehydrated raw material fiber, for example, using a Yankee dryer, the other side and one side in this order, moisture movement occurs in the paper thickness direction, and the moisture content of one side Since it becomes lower later, one surface side contracts later. As a result, it is possible to obtain a structural curl having one side as the outside and the paper making direction as the axial direction. This structural curl is a so-called irreversible curl and has high stability.

That is, using a paper machine equipped with a long-mesh wire and a Yankee dryer, the other surface side from which the short fibers in contact with the long-mesh wire dropped off is dried first, and one of the short fibers not in contact with the long-mesh wire is included. By drying the surface side later, it is possible to obtain a structural curl with one surface side as the outside, so that a glass interleaving paper with higher uprightness and better curl stability against humidity changes can be obtained. preferable.

  And the freeness of the disaggregated pulp is 400 to 650 ml, the fibrillation rate is 2.5 to 4.5%, the mass ratio of NBKP to LBKP is 2:98 to 20:80, and the tensile strength and the transverse direction It is preferable to make the paper so that the ratio of the tensile strength is 0.40 or more and 0.85 or less, since a glass interleaving paper having particularly high uprightness and excellent curl stability against humidity change can be obtained.

  In addition, if the glass interleaving paper of the present invention is a single glossy paper in which a glossy surface is formed by applying a Yankee dryer only to one surface side, the smoothness of one surface side with many short fibers is increased and the gap between the fibers is increased. Can be made smaller, so that a particularly stable curl can be obtained. Moreover, the paper which dried both surfaces with the multicylinder dryer as mentioned above may be sufficient. Moreover, although the planarization process by a calendar may be performed only on one side, it is preferable to perform it on both sides.

(Pulp fiber)
The pulp fibers are not particularly limited, but hardwood bleached kraft pulp (LBKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), softwood unbleached kraft pulp (NUKP), waste paper pulp (DIP) Mechanical pulp (TMP) or the like can be used alone or in combination of two or more.

  Among these pulp fibers, a glass plate that requires a cleanliness is bleached and mixed with softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP) whose resin content is controlled to be low. It is preferable. Moreover, LBKP containing many short fibers can also be used alone. In this case, in the disaggregated pulp, the total amount of NBKP and LBKP is preferably 80% by mass or more, more preferably 95% by mass or more, and particularly preferably 98% by mass or more.

  When NBKP and LBKP are mixed and used in the raw material pulp, the mass ratio (mixing ratio) between NBKP and LBKP is preferably 2:98 or more and 20:80 or less, and more preferably 5:95 or more and 15:85 or less. When the mass ratio is less than the above range, it is difficult to impart sufficient rigidity to the glass interleaving paper, and the occurrence of structural curl is less likely to occur, and the stability of the curl against humidity changes may be likely to decrease. is there. When the mass ratio exceeds the above range, the short fiber ratio of the glass interleaving paper decreases, the interfiber gap increases, the water absorbability of the glass interleaving paper increases, and the curl stability against changes in humidity decreases. There is a fear. In addition, formation unevenness due to binding of pulp fibers may easily occur.

  In the present invention, it is an essential condition that the disaggregated pulp contains short fibers having a fiber length of less than 1.2 mm, and the content of the short fibers is 40% by mass or more. The content of the short fibers is preferably 50% by mass or more, and most preferably 65% by mass or more and 85% by mass or less. If the short fiber content is less than the above range, it may be difficult to make a difference in fiber density between the one side and the other side, and the curl may easily change due to moisture absorption and desorption. There is. Conversely, when the content of short fibers exceeds the above range, the pulp fibers tend to be densely clogged by the flattening treatment, and the curl may change even if a little moisture is absorbed, and the stability of the curl decreases. May be easier. Further, the curl degree becomes too strong, and the stability of the curl may be lowered. The fiber length means a mass-weighted average fiber length, and is a value measured according to a fiber length measurement method by an optical automatic analysis method described in JIS-P8226 (2006). In the present invention, “short fiber” means a fiber having a fiber length of less than 1.2 mm, and “short fiber content” means the total mass of fibers having a fiber length of less than 1.2 mm. The value divided by mass.

  In the glass interleaving paper of the present invention, the ratio of the content rate on the other surface side to the content rate on the one surface side of the short fibers is 0.61 or more and 0.92 or less, more preferably 0.67 or more. 0.85 or less. When the content ratio is less than the above range, the difference in fiber density between one side and the other side becomes large, so the degree of structural curl becomes too strong and the curl changes due to moisture absorption and desorption. The curl stability may be reduced. On the other hand, when the content ratio exceeds the above range, the difference in fiber density between one surface side and the other surface side becomes small, so an appropriate structural curl cannot be obtained, and the curl is not obtained by other methods. Even if it is applied, the curl may be easily changed by moisture absorption / release.

  The freeness of the pulp obtained by separating the glass interleaving paper is preferably 400 ml or more and 650 ml or less, more preferably 450 ml or more and 600 ml or less, and further preferably 470 ml or more and 550 ml or less. When the freeness is less than the above range, in the glass interleaving paper, the fiber-to-fiber bond becomes strong and the curl degree becomes too strong, and the stability of the curl may be lowered. There is a risk. On the other hand, when the freeness exceeds the above range, in the glass interleaving paper, the interfiber bonding is weak and curling is difficult to occur, and the curl stability against humidity change may be reduced, and the binding of pulp fibers A decrease in formation and an increase in surface roughness may occur, and the glass may be easily damaged when the glass interleaf is inserted between the glass plates.

  As a fibrillation rate of the pulp which disaggregated the said glass interleaving paper, 2.5% or more and 4.5% or less are preferable, 2.8% or more and 4.0% or less are more preferable, 3.0% or more and 3.5 or less % Or less is more preferable. When the fibrillation rate is less than the above range, in the glass interleaving paper, the inter-fiber bond is weak and structural curling is difficult to occur, and even when curling is applied by other methods, the curling changes due to moisture absorption and desorption. May be easy to do. On the other hand, when the freeness exceeds the above range, in the glass interleaving paper, the bond between fibers becomes strong and the curl degree becomes too strong, and the curl is easily changed by moisture absorption and desorption, and the stability of the curl is lowered. There is a risk.

  Note that the average fiber length and fibrillation rate of the disaggregated pulp can be adjusted by setting the pulp concentration, pH, temperature, and the like at the time of beating. Also, when beaten with a disc type refiner, the average fiber length and fibrillation rate can be adjusted by appropriately selecting the shape of the disc plate (disk) (blade width, groove width, blade length, etc.), contact angle, blade material, etc. It can also be adjusted.

  For example, when beating with a disk plate having a low concentration at the time of beating, a high temperature, a narrow blade width and a short blade length, the average fiber length tends to decrease. On the other hand, when beaten with a disk plate having a high concentration, a low temperature, a wide blade width and a long blade length, the fibrillation rate tends to increase. In the present invention, by adjusting the average fiber length and the fibrillation rate within arbitrary ranges as described above, the glass composite having better uprightness and stability in which the curl is not easily deformed by humidity. Paper can be suitably obtained.

  In the glass interleaving paper, it is preferable to internally add a wetting improver (surfactant) into the paper. By internally adding a wetting improver, even if a substance in the paper adheres to the glass surface, it is possible to prevent the wettability of the glass surface from being lowered, and it is possible to improve the detergency of the glass with an aqueous solution.

  Examples of the wetting improver include surfactants such as polyoxyalkylene fatty acid ester, polyoxyalkylene alkyl ether, and polyoxyethylene nonylphenyl ether. Among these, polyoxyalkylene fatty acid esters are preferred because they are versatile and inexpensive compared to other surfactants. In addition, the polyoxyalkylene fatty acid ester has good fixation to the pulp fiber, and can improve the disaggregation property of the pulp fiber after discarding the glass interleaving paper.

  In addition to the above wetting improver, sizing agent, dryer release agent, etc. can be internally added to the glass interleaving paper, but in order to suppress the transition to glass, these internal additives should be added as little as possible. Preferably there is.

(Coating layer)
In the glass interleaving paper, a coating layer mainly composed of pigments such as calcium carbonate and clay can be provided on both sides. By providing such a coating layer, the resin component present on the surface of the glass interleaving paper is prevented from transferring to glass, and the glass is contaminated when the glass interleaving paper is inserted between the glass plates. Can be suppressed.

(Calendar processing)
In the glass interleaving paper, it is preferable to perform a flattening process with a calendar on both sides. By performing the flattening process in this way, the surface roughness of the glass interleaving paper can be reduced, and contamination of the glass when the glass interleaving paper is inserted between the glass plates can be suppressed. In addition, the flattening treatment increases the bond between the fibers, and the moisture absorption rate of the glass interleaving paper decreases. Accordingly, the glass interleaving paper is prevented from being deformed by absorbing moisture even in a high humidity environment, and the curl degree can be kept stable. As the flattening apparatus in this case, for example, various calendars composed of a combination of a metal roll and an elastic roll such as a super calendar, a gloss calendar, and a soft compact calendar can be used as appropriate in an on-machine or off-machine specification.

  Hereinafter, although the numerical characteristic of the glass interleaving paper of this invention is described, unless otherwise indicated, the characteristic in "the standard state for paper, paperboard, and pulp-humidity control and a test" of JIS-P8111 (1998) It is.

(Basis weight)
The basis weight of the glass interleaving paper is preferably 30 g / m ² or more and 70 g / m ² or less, and more preferably 40 g / m ² or more and 55 g / m ² or less. When the basis weight is less than the above range, the glass interleaving paper may not exhibit sufficient uprightness and may have reduced buffering properties. On the other hand, when the basis weight exceeds the above range, in the glass interleaving paper, handling property may be lowered and production cost may be increased.

(Tensity)
The tension of the glass interleaving paper is preferably 0.55 g / cm ³ or more and 1.2 g / cm ³ or less, more preferably 0.6 g / cm ³ or more and 1.2 g / cm ³ or less, and 0.7 g / cm ^{3. 3 to} 1.1 g / cm ³ is particularly preferable. When the tightness is less than the above range, the entanglement between the fibers is reduced, and the curl may be easily changed due to a change in humidity. On the other hand, when the tension exceeds the above range, the fiber-to-fiber bond of the glass interleaving paper tends to become dense, and the curl may change even if a little moisture is absorbed, and the stability of the curl is likely to decrease. In addition to this, when the glass interleaving paper is inserted between the glass plates, the glass may be easily damaged due to uneven formation.

  To adjust the tension, a conventionally known technique may be used. For example, a method of reducing compression by reducing a press pressure or a calendar pressure, a method of selecting a tree species from which a bulky pulp fiber is obtained, a fiber such as a bulking agent There is a method of containing an intermolecular binding inhibitor.

(Curl height)
In the glass interleaving paper, the average curl height at the four corners is preferably 5 mm or more and 20 mm or less, more preferably 8 mm or more and 15 mm or less when cut into a 300 mm square having one side as the paper making direction. . By controlling the curl height within the above range, the glass interleaving paper can achieve both uprightness and curl stability against humidity change. When the curl height is less than the above range, the glass interleaving paper may not exhibit sufficient uprightness. On the other hand, when the curl height exceeds the above range, the curl degree becomes too strong, and the stability of the curl of the glass interleaving paper may be lowered.

  To improve the curl height, adjust the dehydration method (number of foils, degree of vacuum, etc.) with a wire to increase the difference between the content of one side of the short fiber and the content of the other side, dryer There are a method of increasing the drying balance of the front and back by changing the vapor pressure of the material, a method of improving the fibrillation rate, a method of reducing the filler content, and the like.

(Aspect ratio of tensile strength)
The ratio of the tensile strength in the longitudinal direction and the tensile strength in the transverse direction (Y / T ratio) of the glass interleaving paper is preferably 0.40 or more and 0.85 or less, and more preferably 0.50 or more and 0.70 or less. . When the Y / T ratio is less than the above range, the degree of curling becomes too strong in the glass interleaving paper, and the stability of curling with respect to the humidity of the glass interleaving paper may be lowered. On the other hand, when the Y / T ratio exceeds the above range, the glass interleaving sheet is likely to be curled with the papermaking direction and the vertical direction as the axial direction. The curl tends to change due to moisture absorption and release, and the stability of the curl against humidity may be reduced.

(Smoothness)
In the glass interleaving paper, the Beck smoothness on one side relative to the Beck smoothness on the other side is preferably 1.2 times or more and 40 times or less, and more preferably 2 times or more and 35 times or less. It is more preferably 5 times or more and 30 times or less, and particularly preferably 10 times or more and 30 times or less. Thus, by increasing the Beck smoothness of one surface side than the other surface side and increasing the contact area between the pulp fibers, the area where the moisture in the air and the pulp fibers present on the one surface side come into contact with each other And the glass interleaving paper is less likely to absorb moisture on one side compared to the other side. As a result, the glass interleaving paper is likely to stably develop curl with one side facing inward. Moreover, by setting the ratio of the smoothness between the one surface side and the other surface side within the above range, a preferable curl degree can be achieved, and the uprightness and handling property of the glass interleaving paper can be further improved. When the smoothness ratio is less than the above range, a sufficient curl shape is hardly exhibited, and the uprightness of the glass interleaving paper may be reduced. On the contrary, when the smoothness ratio exceeds the above range, the curl degree becomes too strong, and the stability of the glass interleaving paper against the humidity of the curl may be lowered.

  As specific Beck smoothness for obtaining a suitable curl degree and stability of the curl with respect to humidity, one side is preferably 10 seconds or more and 1,000 seconds or less, more preferably 50 seconds or more and 600 seconds or less. 100 seconds or more and 400 seconds or less is more preferable. The other surface side is preferably 1 second to 500 seconds, more preferably 2 seconds to 200 seconds, and even more preferably 5 seconds to 50 seconds.

(Moisture percentage)
In the glass interleaving paper, in addition to setting the density within the above range, the moisture content is preferably 2% or more and 8% or less, and more preferably 3% or more and 7% or less. By adjusting the density and moisture content of the glass interleaving paper to the above ranges, in the glass interleaving paper, it is possible to achieve an appropriate degree of curling, as well as to suppress the generation of static electricity and to exhibit appropriate air permeability. , Handling is enhanced. When the moisture content is less than the above range, the glass interleaving paper may be difficult to adjust curl or may be likely to generate static electricity. Moreover, there exists a possibility that handling property at the time of using a vacuum device may fall because air permeability becomes high. On the other hand, when the moisture content exceeds the above range, the adhesiveness between the glass plate and the glass interleaving paper is increased by containing a large amount of moisture, and the handling property may be lowered.

  The moisture content can be controlled by adjusting the linear pressure in the compression / dehydration process using a roll press after papermaking, adjusting the vapor pressure of the Yankee dryer, and the like.

  The air resistance of the glass interleaving paper is preferably 5 seconds or more and 30 seconds or less in order to ensure good handling when using a vacuum device. The air resistance can be measured by the Gurley method described in JIS-P8117 (2009).

(Stiffness (longitudinal direction))
The stiffness of the glass interleaving paper in the longitudinal direction is preferably 20 or more and 80 or less, and more preferably 25 or more and 70 or less. By setting the rigidity in the longitudinal direction of the glass interleaving paper within the above range, more excellent uprightness can be exhibited, and the handling property of the glass interleaving paper is further enhanced. When the stiffness is less than the above range, the uprightness and handling properties of the glass interleaving paper may be reduced. On the other hand, when the stiffness exceeds the above range, handling properties may be deteriorated, for example, it becomes difficult to wind up the glass interleaving paper.

(Surface roughness)
The glass interleaving paper preferably has a surface roughness within a certain range in order to prevent damage to the glass when the glass interleaving paper is inserted between the glass plates. Specifically, the value measured according to JIS-P8151 with soft backing and clamp pressure of 1 MPa using PPS TESTER (model number: SE-115 Lorenzen & Bettley) is 1.0 μm or more and 10.0 μm. The following is preferable. When the surface roughness exceeds the above range, there is a possibility that the glass plate is easily damaged when the glass interleaf is inserted between the glass plates. On the other hand, when the surface roughness is less than the above range, it may be difficult to produce the glass interleaving paper.

<Laminate>
The laminate of the present invention is formed by alternately laminating glass plates and the glass interleaving paper. Examples of the glass plate include glass substrates used in flat panel displays such as liquid crystal televisions and plasma televisions. As this glass substrate, a large substrate having a side of 1,500 mm or more can be used. According to the said laminated body, the glass plate is protected by the said glass interleaving paper, and it is excellent in workability | operativity, such as insertion and extraction of a glass plate and glass interleaving paper.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

  In addition, the evaluation method of quality and performance performed in the present Example is as follows.

[Freeness (unit: ml)]
The glass interleaving paper was disaggregated by the method described in JIS-P8220 (1998) to obtain disaggregated pulp, and this disaggregated pulp was measured in accordance with the “pulp freeness test method” described in JIS-P8121.

[Fibrosis rate (unit:%)]
The glass interleaving paper was disaggregated by the method described in JIS-P8220 (1998) to obtain disaggregated pulp, and FiberLab. (Kajaani) was used for measurement.

[Basis weight (unit: g / m ² )]
It was measured in accordance with “Paper and paperboard—Method for measuring basis weight” described in JIS-P8124 (1998).

[Intensity (Unit: g / cm ³ )]
It was measured in accordance with “Paper and paperboard—Test method for thickness and density” described in JIS-P8118 (1998).

[Curl height (unit: mm)]
The glass interleaving paper was cut into a 300 mm square with the paper making direction as one side, and left for 1 hour in an environment of a temperature of 23 ° C. and a humidity of 50%. Then, the glass interleaving paper cut | disconnected so that the other surface side might contact was put on the flat surface (plate). That is, the glass interleaving paper was placed so that one side faced up, the height from the plate surface at the four corners was measured, and an average value was obtained for 10 specimens.

[Aspect ratio of tensile strength]
The tensile strength in the longitudinal direction and the transverse direction is measured in accordance with “Paper and paperboard—Test method for tensile properties—Part 2: Constant speed extension method” described in JIS-P8113 (2006), and the Y / T ratio is measured. Was obtained by the following equation.
Y / T ratio = tensile strength (horizontal direction) / tensile strength (longitudinal direction)

[Uprightness]
The operation | work which inserts a glass slip sheet between glass plates using the vacuum apparatus was performed in 20 glass slip sheets, and the following references | standards evaluated.
(Double-circle): After inserting glass interleaving paper between glass plates, 90% or more are maintained upright.
○: After inserting the glass slip sheet between the glass plates, the upright is maintained at 70% or more and less than 90%.
X: After inserting the glass slip between the glass plates, less than 70% is maintained upright.

[Curl stability]
Following the curl height test, the degree of curl deformation after the glass interleaving paper was left in an environment of a temperature of 23 ° C. and a humidity of 65% for 1 hour was evaluated according to the following criteria.
A: No curl deformation is observed.
○: Curled deformation is hardly observed.
Δ: Some curl deformation is observed.
X: The curl is greatly deformed and the stability is insufficient.

[Example 1]
3 kg / t of saponified rosin and 3 kg / t of sulfuric acid band as sizing agents were added to a pulp slurry containing NBKP and LBKP to obtain a raw material slurry. In addition, the compounding ratio of used NBKP and LBKP is 10:90. In addition, the raw material pulp was beaten so that the content of short fibers having a fiber length of less than 1.2 mm in the disaggregated pulp obtained by disaggregating the glass interleaf after papermaking was 75% by mass.

This raw material slurry was made with a long paper machine and dried on one side with a Yankee dryer, and then subjected to calendar treatment on both sides to obtain the glass interleaving paper of Example 1. In the glass interleaving paper of Example 1, the ratio of the other surface side content to the one surface side content of the short fibers is 0.82, the basis weight is 50 g / m ² , and the tension is 1.0 g / cm. ³ . Moreover, the disaggregation pulp freeness obtained by disaggregating the glass interleaving paper was 500 ml, and the fibril rate was 3.3%.

[Examples 2 to 5]
The glass interleaving papers of Examples 2 to 5 were produced in the same manner as in Example 1 except that the ratio of NBKP and LBKP in the raw material pulp was changed as shown in Table 1.

[Examples 6 to 9, 23 to 26, and Comparative Examples 1 and 2]
Examples 6 to 9 were the same as in Example 1 except that the ratio of NBKP and LBKP in the raw pulp and the linear pressure in the calendar process were adjusted so that the tension became the value shown in Table 1. Glass interleaving papers 23 to 26 and Comparative Examples 1 and 2 were produced.

[Examples 10 to 13 and Comparative Examples 3 and 4]
Other than adjusting the dehydration method (number of foils, degree of vacuum, etc.) with the wire so that the ratio of the content of the other surface to the content of one surface of the short fiber is the value shown in Table 1. The conditions were the same as in Example 1, and glass slip sheets of Examples 10 to 13 and Comparative Examples 7 and 8 were produced.

[Examples 14 to 18]
Glass interleaving papers of Examples 14 to 18 were manufactured in the same manner as in Example 1 except that the drying pressure on the front and back sides was adjusted by changing the vapor pressure of the dryer.

[Examples 19 and 20]
The same conditions as in Example 1 except that the J / W ratio (velocity ratio between the jetting raw material and the wire) was adjusted so that the Y / T ratio became the value shown in Table 1. 19 and 20 glass slip sheets were produced.

[Examples 21 and 22]
The conditions other than the adjustment of the raw pulp beating method (cutting, viscosity, etc.) so that the freeness and fibrillation rate of the disaggregated pulp are the values shown in Table 1 are the same as in Example 1. Glass slip sheets of Examples 21 and 22 were produced.

  The quality and performance of each slip sheet obtained by the method described above were evaluated. The evaluation results are shown in Table 1.

  As shown in Table 1, the glass interleaving papers of Examples 1 to 26 have good uprightness without strict adjustment of basis weight, raw material pulp, etc., and also in curl stability against humidity change. It turns out that it is excellent. In addition, the glass interleaving paper of Comparative Example 6 has high hardness, and when inserted between the glass plates, there is a risk of scratching the glass due to uneven formation or the like, which is also not suitable for practical use from this point.

  As described above, the glass interleaving paper of the present invention can be suitably used as interleaving paper for glass substrates used for flat panel displays such as liquid crystal televisions and plasma televisions.

Claims (5)

A glass interleaving paper obtained by papermaking a raw material mainly composed of pulp fiber,
The disaggregated pulp which disaggregated the glass interleaving paper contains the short fiber whose fiber length is less than 1.2 mm,
The content of the short fibers in the disaggregated pulp is 40% by mass or more,
A glass interleaving paper, wherein the ratio of the content ratio of the other surface side to the content ratio of one surface side of the short fiber is 0.61 or more and 0.92 or less.   The glass interleaving paper according to claim 1, wherein the disintegrated pulp has a freeness of 400 to 650 ml and a fibrillation rate of 2.5 to 4.5%.   The said disaggregation pulp contains softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP), and mass ratio of NBKP and LBKP is 2:98 or more and 20:80 or less, The claim 1 or Claim 2 Glass slip paper. The average curl height at the four corners when cut into a 300 mm square with one side as the paper making direction is 5 mm or more and 20 mm or less,
The glass interleaving paper according to claim 1, wherein the ratio of the tensile strength in the transverse direction to the tensile strength in the longitudinal direction is 0.40 or more and 0.85 or less. The laminated body by which a glass plate and the glass interleaving paper of any one of Claims 1-4 are laminated | stacked alternately.