JP6783566B2 - Glass interleaving paper and its manufacturing method - Google Patents

Description

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

In the distribution process in which a plurality of glass plates are laminated, stored and transported, a slip sheet is generally sandwiched between the glass plates for the purpose of preventing the glass plates from cracking, scratching the surface of the glass plates, and contaminating the glass plates. In recent years, with the diversification of glass applications, a high degree of cleaning of the glass plate surface has been required, so that the quality requirement for interleaving paper is also increasing. In particular, high quality (cleanliness) is required for glass plates used for panels of smartphones and tablets that are operated by human hands.

In the conventional glass interleaving paper, resin components such as silicone contained in the interleaving paper and which cannot be easily removed by cleaning when adhering to the glass surface may adhere to the glass surface and cause contamination of the glass surface. Are known. Such contamination causes a great obstacle in processing such as vapor deposition, metal film treatment, and plating on the surface of the glass plate, particularly on the surface of the chemically strengthened glass plate whose demand has been increasing dramatically in recent years.

Under these circumstances, a glass interleaving paper having a silicone content of 0.1 ppm or less has been proposed as an interleaving paper in which the adhesion of organic substances to the glass plate is prevented (see International Publication No. 2014/104187). However, in this glass interleaving paper, it is necessary to use raw material pulp having an extremely small amount of silicone, and it is necessary to spend a great deal of cost and labor in preparing the raw material pulp. Therefore, there is a demand for the development of a glass interleaving paper that can reduce the adhesion of the resin component to the glass plate without adjusting the silicone content of the raw material pulp.

International Publication No. 2014/104187

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 capable of reducing adhesion of a resin component to a glass plate, and a method for producing such a glass interleaving paper. That is.

The invention made to solve the above problems has a base paper containing pulp fiber as a main component and a surfactant and a sizing agent added therein, and the SP value of the sizing agent is 7 or more and 10 or less. It is a glass interleaving paper.

Since the glass interleaving paper contains a surfactant and a sizing agent having a predetermined SP value, it is possible to reduce the adhesion of a resin component such as silicone to the glass plate. The reason for this is not clear, but the following reasons can be inferred. The SP value of silicone such as silicone oil is usually 7 or more and 10 or less. Therefore, the same sizing agent having an SP value of 7 or more and 10 or less has high compatibility with silicone, and together with the surfactant, a micellar structure formed with silicone as a core as a core can be formed particularly finely. it can. Since this fine micellar structure is strongly adhered to the pulp fiber surface in the obtained glass interleaving paper, adhesion of silicone or the like to the glass surface is suppressed. Further, even when silicone or the like adheres to the glass surface, it adheres as a micellar structure together with the surfactant or the like, so that it can be washed off relatively easily by washing with water or the like.

It is preferable that the sizing agent is a rosin-based sizing agent. By using a rosin-based sizing agent having a predetermined SP value, the contamination prevention function of the glass plate surface can be further enhanced. The rosin-based sizing agent is conventionally known in the paper manufacturing field as long as it satisfies a predetermined SP value, and is not particularly limited. Examples of rosin-based substances include fortified rosins obtained by modifying rosins such as gum rosin, wood rosin, and tall oil rosin with α, β-unsaturated carboxylic acids such as fumaric acid, maleic acid, and acrylic acid, or rosins thereof, and the above-mentioned rosins. Examples thereof include rosin esters obtained by reacting polyhydric alcohols such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and diglycerin. In addition, the rosin-based sizing agent includes those obtained by emulsifying these alone or a mixture thereof, and those obtained by emulsifying alone and then mixing them. Further, the above-mentioned emulsified product to which various polymers are added in order to further improve the size expression is also included.

It is preferable that the surfactant is a nonionic surfactant. By using a nonionic surfactant, the stain prevention function on the surface of the glass plate can be further enhanced. Nonionic surfactants include fatty acid esters of polyhydric alcohols, alkylene oxide adducts of fatty acid esters of polyhydric alcohols, alkylene oxide adducts of fatty acid amides and fatty acid amides, alkylene oxide adducts of alkylamines, alcohols and alcohols. The alkylene oxide adduct of the above, a polyalkylene glycol having an oxyalkylene group having 2 to 4 carbon atoms as a constituent unit, and preferably a polyalkylene glycol having an oxyalkylene group having 3 to 4 carbon atoms as a constituent unit. Among these, a liquid self-emulsifying surfactant that is fatty acid-based and does not contain silicone is more preferable.

It is preferable that the pulp fiber is dry pulp. The dry pulp refers to pulp having a drying history, which is once dried after the production of raw material pulp. The glass interleaving paper is preferably single-gloss paper. The single-glossy paper is usually obtained by heating and drying with a Yankee dryer after papermaking, and one side is made into a highly glossy glossy surface. During heating and drying with a Yankee dryer, the resin content such as silicone remaining in the base paper moves to the non-glossy surface side together with the evaporating water. In particular, in the glass interleaving paper, since a fine micellar structure is formed by using a specific sizing agent, it efficiently moves to the non-glossy surface side and is firmly fixed to the pulp fiber surface. .. Therefore, the amount of resin such as silicone remaining on the glossy surface is reduced, and even if the glossy surface is in close contact with the glass surface, it is difficult for the resin content such as silicone to transfer to the glass. Further, since the non-glossy surface has low smoothness and the surface is uneven, the adhesion to the glass is low, and the transferred resin component such as silicone is firmly fixed to the pulp fiber, so that the non-glossy surface is transferred to the glass. Is reduced.

Another invention made to solve the above problems includes a step of making a pulp slurry containing pulp fiber as a main component and a surfactant and a sizing agent, and the SP value of the sizing agent is 7 or more and 10 or less. Yes, the content of the surfactant in the pulp slurry with respect to the pulp fiber is 0.1 kg / pulp t or more and 6 kg / pulp t or less, and the content of the sizing agent in the pulp slurry with respect to the pulp fiber is 3 kg / pulp t or more and 8 kg. / A method for producing glass interleaving paper having pulp t or less.

According to the manufacturing method, a glass interleaving paper in which a surfactant and a sizing agent having a predetermined SP value are embedded in a base paper to reduce adhesion of a resin such as silicone to a glass plate. Obtainable. Further, according to the production method, at the time of papermaking, a sizing agent having a predetermined SP value and a surfactant form a fine micelle structure centered on silicone, which is an oil component, and the micelle structure is formed. Because it is fine, it is easily discharged to the outside of the system (outside the base paper). As a result, the oil content itself such as silicone remaining on the base paper can be reduced, and a glass interleaving paper in which the adhesion of the resin content to the glass substrate is reduced can be obtained.

According to the present invention, it is possible to provide a glass interleaving paper capable of reducing adhesion of a resin component to a glass plate, and a method for producing such a glass interleaving paper.

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

<Glass interleaving paper>
The glass interleaving paper has a base paper containing pulp fiber as a main component and a surfactant and a sizing agent added therein, and the SP value of the sizing agent is 7 or more and 10 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 fibers are not particularly limited, and are broad-leaved bleached kraft pulp (LBKP), coniferous bleached kraft pulp (NBKP), broad-leaved unbleached kraft pulp (LUKP), coniferous unbleached kraft pulp (NUKP), waste paper pulp (DIP), One type or a mixture of two or more types of mechanical pulp (TMP) and the like can be used.

In particular, pulp that can be preferably used is from wood to pulp in a paper machine that combines a known circular net or long net and a multi-cylinder dryer, a pulp machine, or a pulp machine that combines a sheet forming device and another hot air drying device. The raw pulp obtained through the chemical conversion step is dried, and the dry pulp dried to a water content of 3 to 25% (per absolute dry pulp weight), preferably 5 to 20% is preferable. Used. Dry pulp dried to 5 to 20% of water is not only effective in reducing the expansion and contraction rate when made into paper, but also extremely effective in reducing the water absorption rate. Furthermore, it is made into glass by making it as a single-gloss paper. Dimensional stability suitable for interleaving paper can be obtained.

Furthermore, dry pulp tends to retain the entangled state of pulp fibers formed in a wet state even after drying, and is compared with paper made from raw pulp obtained through a pulping process from wet wood having no drying history. However, the cushioning property and smoothness required when used as a glass interleaving paper are likely to be exhibited, and in particular, the void ratio after papermaking is likely to be high as a single-gloss paper, and the desired action and effect in the present invention are exhibited. It is presumed to be.

If the water content of the pulp is dried to less than 3%, the pulp fiber deteriorates, which may not be suitable. If the water content exceeds 25%, the water content in the pulp fiber molecule cannot be removed. , The quality is equivalent to that of the raw material pulp obtained through the pulping process and does not contribute to the improvement of dimensional stability, which may be unsuitable.

Among these pulp fibers, softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP), which are bleached to a low resin content on a glass plate that requires a degree of cleanliness, are preferable, and LBKP is preferable. More preferred. The content of LBKP in the total pulp fiber is preferably 80% by mass or more, more preferably 95% by mass or more, still more preferably 100% by mass.

As the lower limit of the freeness of the pulp fiber, 450 mL is preferable, 500 mL is more preferable, and 520 mL is further preferable. On the other hand, as the upper limit, 650 mL is preferable, 600 mL is more preferable, and 550 mL is further preferable. If the freeness is less than the above lower limit, the density increases, so that the resin component tends to remain in the base paper, and the adhesion of the resin component to the glass plate may not be sufficiently reduced. On the contrary, when the freeness exceeds the above upper limit, the formation unevenness due to the binding of the pulp fibers is likely to occur, and the resin component may be likely to remain partially, and as a result, the resin component adheres to the glass plate. May not be reduced sufficiently.

(Surfactant)
In the pulp slurry, the surfactant forms a micellar structure with a resin component such as silicone as a core together with a sizing agent, and a part of the surfactant is discharged to the outside of the base paper during papermaking and a part of the surfactant is inside the base paper. Remains in. Further, the surfactant existing as a micelle structure together with the resin component in the base paper can be easily washed away even when it adheres to the surface of the glass plate because it is a highly wet surfactant. Therefore, the detergency and cleanliness of the glass plate can be improved.

Examples of the above-mentioned surfactant include cationic surfactants (alkyltrimethylammonium salt, alkylbenzyldimethylammonium salt, etc.), anionic surfactants (alkylsulfate, alkylbenzenesulfonate, etc.), and amphoteric surfactants (alkyldimethyl). Aminoxide, alkylcarboxybetaine, etc.), nonionic surfactants, etc. can be mentioned, but nonionic surfactants are more preferable. By using a nonionic surfactant in combination with a size agent having a pH of 7 or more and 10 or less, the micellar structure having an oil component such as silicone as a core becomes finer and is easily discharged to the outside of the base paper during papermaking. At the same time, the cleanability when it adheres to the glass plate is improved.

Examples of the nonionic surfactant include fatty acid esters such as polyoxyalkylene fatty acid esters, higher alcohol-based surfactants such as polyoxyalkylene alkyl ether, and alkylphenol-based surfactants such as polyoxyethylene nonylphenyl ether. be able to. Among these, fatty acid esters are preferable from the viewpoint of being able to further improve the cleanliness of the glass plate.

(Size agent)
The above-mentioned sizing agent having an SP value of 7 or more and 10 or less has high compatibility with silicone, and together with a surfactant, can form a micellar structure formed with silicone as a nucleus in a particularly fine size. .. Since this fine micellar structure is strongly adhered to the pulp fiber surface in the obtained glass interleaving paper, adhesion of silicone or the like to the glass surface is suppressed. Further, even when silicone or the like adheres to the glass surface, it adheres as a micellar structure together with the surfactant or the like, so that it can be washed off relatively easily by washing with water or the like.

As the lower limit of the SP value, 8 is preferable, 8.5 is more preferable, and 9 is further preferable. Further, the upper limit of the SP value is more preferably 9.5. When the SP value is in the above range, the cleanliness of the glass interleaving paper can be further improved because a finer micellar structure can be formed with silicone or the like.

The SP value (Solubility parameter) refers to the square root (unit (cal: cm ^-3 ) ^1/2 ) of the aggregation energy density of a two-component regular solution (Regular solution), and is referred to as "latest paper processing." It can be calculated by the method described in lines 523 to 524 of "Handbook" (issued by Tech Times on August 20, 1988).

Wax compounds with an SP value of 7.5 (“Size Pine W-116H” from Arakawa Industrial Co., Ltd.) and rosin compounds with an SP value of 8.5 (Misawa Ceramics) are examples of sizing agents with an SP value of 7 or more and 10 or less. "RF size 880L-50"), rosin compound with SP value of 9.3 ("Size Pine E-50" by Arakawa Chemical Industries, Ltd.), polyethyleneimine resin with SP value of 9.7 (BASF) Japan's "Polymin SN") and the like can be mentioned.

Among the above sizing agents, rosin-based sizing agents (rosin-based compounds) are preferable. When a rosin-based sizing agent is used, the contamination prevention function of the glass plate surface can be further enhanced because a finer micellar structure can be formed with silicone or the like.

The sizing agent is preferably an alkaline sizing agent. The reason is as follows. The surface pH of the glass interleaving paper is preferably adjusted to 3 or more and 6 or less, more preferably 3 or more and 5 or less. If a sulfuric acid band is added so that the pH of the paper surface is less than 3, the pulp fibers are agglomerated and flocs are likely to be generated, resulting in poor formation and easy scratches during transportation of the glass plate. It is desirable not to add the sulfuric acid band in consideration of the formation, but it may be added in consideration of the dryer peelability and fixability. By using such a sizing agent, the surface pH of the glass interleaving paper can be effectively adjusted to a suitable range. Examples of such an alkaline sizing agent include a reaction product of rosin (abietic acid) represented by the following formula and maleic anhydride (maleic anhydride).

Since this maleinated rosin has a plurality of carboxy groups (including an acid anhydride group) in one molecule, it has high fixability to pulp fibers, and a micelle structure centered on a resin component is formed on the pulp fiber surface. Can be strongly attached to. Therefore, when such a sizing agent is used, it is possible to further reduce the adhesion of the micellar resin component to the surface of the glass plate. Specific examples of such alkaline maleated rosin include "Size Pine E", "Size Pine E-50", "Size Pine E-K", and "Size Pine E-K-" manufactured by Arakawa Chemical Industries, Ltd. 50 ”and the like.

Further, it is preferable to use a nonionic surfactant as the surfactant and a nonionic sizing agent as the sizing agent. By using both nonionic components in this way, the affinity with silicone and the like is further enhanced, and a finer micellar structure can be formed. Therefore, in this case, the micelle structure can be effectively discharged to the outside of the base paper during papermaking to reduce the resin content, and the micelle structure remaining in the base paper is also on the pulp fiber surface. It adheres strongly and can suppress adhesion to the glass plate. Examples of the nonionic sizing agent include "Size Pine E", "Size Pine E-50", "Size Pine EK", and "Size Pine E-K-50" manufactured by Arakawa Chemicals. it can.

(Other ingredients, etc.)
In the base paper of the glass interleaving paper, an internal additive other than the above-mentioned surfactant and sizing agent can be internally added. Examples of such an internal additive include a sulfate band, an antifoaming agent, a dryer release agent, and the like. However, in order to reduce the transfer of these internal additives to the glass plate, it is preferable that the amount is as small as possible within a range that does not affect the peeling of the dryer or the like.

The glass interleaving paper may have another coating layer or the like in addition to the above base paper, but it is preferably composed of only the above base paper. Since the glass interleaving paper is composed of only the base paper, it is possible to further suppress the adhesion of the resin component to the glass plate.

(Smoothness, etc.)
The glass interleaving paper is preferably single-gloss paper. The single glossy paper is usually obtained by heating and drying with a Yankee dryer, and refers to a paper in which only one side is a glossy surface (a glossy surface). By heating and drying with a Yankee dryer, the silicone and the like remaining in the base paper are melted and fixed together with the sizing agent and the like. As a result, the glass interleaving paper has a reduced adhesion of resin to the surface of the glass plate. Further, during heating and drying with a Yankee dryer, the resin component such as silicone remaining in the base paper moves to the non-glossy surface side together with the evaporating water. Therefore, particularly on the non-glossy surface side, in addition to having good adhesion to the glass plate surface, adhesion of the resin component to the glass plate surface is reduced.

Whether or not it is a single-gloss paper can also be defined by the smoothness of the front surface and the back surface. For example, a paper having a Beck smoothness (seconds) on the front surface 5 times or more, preferably 10 times or more the Beck smoothness (seconds) on the back surface can be regarded as a single glossy paper.

As a specific lower limit of the Beck smoothness of the surface (glossy surface), 50 seconds is preferable, 100 seconds is more preferable, and 150 seconds is further preferable. On the other hand, the upper limit may be 300 seconds or 200 seconds. Further, as the lower limit of the Beck smoothness of the back surface (non-glossy surface), 1 second is preferable, 2 seconds is more preferable, and 5 seconds is further preferable. On the other hand, the upper limit may be 30 seconds, 20 seconds, or 10 seconds.

(Basis weight)
As the lower limit of the basis weight of the glass interleaving paper, 30 g / m ² is preferable, and 40 g / m ² is more preferable. On the other hand, as the upper limit, 100 g / m ² is preferable, and 80 g / m ² is more preferable. If the basis weight is less than the above lower limit, the cushioning property may decrease. On the contrary, when the basis weight exceeds the above upper limit, the handleability is lowered and the cost is high.

(How to use, etc.)
The glass interleaving paper is used as a glass interleaving paper that protects the glass plates by inserting them between a plurality of glass plates during transportation or storage of the glass plates. That is, the laminated body in which the glass interleaving paper and the glass plate are alternately laminated is transported or stored. Examples of the glass plate include a glass substrate used for flat panel displays such as LCD TVs, plasma TVs, tablets, and smartphones. When inserting the glass interleaving paper, the surface on the side of the glass plate where it is desired that there is little adhesion of scratches or foreign matter (for example, the surface on which the transparent conductive film is processed) and the glass It is preferable to insert the interleaving paper so that it is in contact with the glossy surface of the interleaving paper. The glossy surface has high adhesion to the glass plate, and as described above, the amount of the resin component on the glossy surface side is reduced in the glass interleaving paper. Therefore, it is possible to effectively suppress scratches on the surface in contact with the glossy surface and adhesion of foreign matter.

As described above, the glass interleaving paper can reduce the adhesion of the resin component to the surface of the glass plate and improve the cleanliness of the surface of the glass plate. Therefore, the glass interleaving paper can be particularly preferably used as a glass interleaving paper for a glass plate for a tablet or a smartphone, which is visually recognized by a person at a short distance and requires particularly high cleanliness.

<Manufacturing method of glass interleaving paper>
The method for producing the glass interleaving paper is not particularly limited, but it can be effectively produced by the following method. That is, the method for producing a glass interleaving paper according to an embodiment of the present invention includes a step of making a pulp slurry containing pulp fibers as a main component and a surfactant and a sizing agent, and the SP value of the sizing agent is 7. The content of the surfactant in the pulp slurry is 0.1 kg / pulp t or more and 6 kg / pulp t or less, and the content of the sizing agent in the pulp slurry in the pulp fiber is 3 kg / or less. Pulp t or more and 8 kg / pulp t or less. The "pulp t" refers to the amount added to the dried pulp fiber 1t.

According to the manufacturing method, a glass interleaving paper in which a surfactant and a sizing agent having a predetermined SP value are embedded in the base paper to reduce the adhesion of resin such as silicone to the glass plate. Obtainable. Further, according to the production method, at the time of papermaking, a sizing agent having a predetermined SP value and a surfactant form a fine micelle structure centered on silicone, which is an oil component, and the micelle structure is formed. Because it is fine, it is easily discharged to the outside of the system (outside the base paper). As a result, the oil content itself such as silicone remaining on the base paper can be reduced, and a glass interleaving paper in which the adhesion of the resin content to the glass substrate is reduced can be obtained.

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

The lower limit of the content of the surfactant in the pulp slurry with respect to the pulp fiber is 0.1 kg / pulp t, preferably 0.3 kg / pulp t, more preferably 0.5 kg / pulp t, 0.8 kg / kg / pulp. Pulp t is more preferable, and 1 kg / pulp t is particularly preferable. On the other hand, the upper limit is 6 kg / pulp t, but 4 kg / pulp t is preferable, 2 kg / pulp t is preferable, and 1.5 kg / pulp t is preferable. When the amount of the surfactant added is less than the above lower limit, the resin content in the pulp slurry is not sufficiently discharged to the outside of the system, and the remaining micellar structure is not sufficiently fixed to the pulp fibers. Adhesion of resin to the board is not sufficiently reduced. On the other hand, if the amount of the surfactant added exceeds the above upper limit, the effect may reach a plateau, the amount of the surfactant adhering to the glass plate may increase, and the cleanliness may decrease.

The lower limit of the content of the sizing agent in the pulp slurry with respect to the pulp fiber is 3 kg / pulp t, but 4 kg / pulp t is preferable. On the other hand, this upper limit is 8 kg / pulp t, but 6 kg / pulp t is preferable, and 5 kg / pulp t is more preferable. If the amount of the sizing agent added is less than the above lower limit, the resin content in the pulp slurry is not sufficiently discharged to the outside of the system, and the remaining micellar structure is not sufficiently fixed to the pulp fibers. Adhesion of resin to the resin is not sufficiently reduced. On the other hand, if the amount of the sizing agent added exceeds the above upper limit, the effect may reach a plateau, the amount of the sizing agent adhering to the glass plate may increase, and the cleanliness may decrease.

In the pulp slurry, other internal additives other than the above-mentioned surfactant and sizing agent may be added, but the amount of the other internal additives added is preferably 10 kg / pulp t or less, preferably 8 kg /. Pulp or less is more preferable. By reducing the amount of other internal additives added, the resin content in the base paper can be reduced, and the adhesion of the resin content to the glass plate can be reduced.

The above-mentioned paper making can be performed by a known method using a long net paper machine or the like.

In the production method, it is preferable to further include a step of heating and drying the pulp slurry (base paper) after the papermaking step with a Yankee dryer. By heating and drying with a Yankee dryer, the silicone and the like remaining in the base paper are melted together with the sizing agent and the like, and are firmly fixed to the pulp fibers. As a result, it is possible to obtain a glass interleaving paper in which the adhesion of the resin component to the glass plate surface is further reduced. Further, when the resin component such as silicone remaining in the base paper is dried by heating with a Yankee dryer, it moves to the non-glossy surface side together with the evaporating water. Therefore, particularly on the non-glossy surface side, in addition to having good adhesion to the glass plate surface, adhesion of the resin component to the glass plate surface is reduced.

<Other Embodiments>
The glass interleaving paper of the present invention and the method for producing the same are not limited to the description of the above-described embodiment. For example, the drying after papermaking can be done by a dryer other than the Yankee dryer.

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

The quality and performance evaluation methods performed in this example are as follows.

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

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

[Freeness (mL)]
The obtained glass interleaving paper was disintegrated in accordance with JIS-P8220 to obtain dissociated pulp, and the dissociated pulp was measured in accordance with JIS-P8121.

[Amount of foreign matter adhering to the glass plate (before cleaning)]
Forty-six non-alkali glass plates for liquid crystal display with a size of 650 x 550 x 0.7 mm were prepared, each glass piece was immersed in a 0.01 mol / liter NaOH aqueous solution for 30 seconds, washed with water, and sprayed with a nitrogen blower. And dried. Next, the glass plates were divided into 23 sets of 2 sheets each, and each of the obtained glass interleaving papers was sandwiched between the two glass plates and placed flat on a transport pallet. Then, in this state, it was kept in a constant temperature and humidity atmosphere of 20 ° C. and 80% RH for 10 days. Next, of each of the two glass plates, the glass plate on the surface in contact with the glossy surface and the non-glossy surface is cut out into a 10 × 10 cm square to prevent foreign matter from adhering to the surface in contact with the glossy surface and the non-glossy surface. The judgment was made visually according to the following criteria.
⊚: No stains or scratches were found on both the glossy surface and the non-glossy surface side.
◯: When illuminated with light, a slight oil film-like adhesion is observed, but it is judged that there is no problem in using it.
Δ: Slight oil film-like adhesion was observed, but it is judged that there is no problem in use.
X: Oil film-like stains are scattered.

[Amount of foreign matter adhering to the glass plate (after cleaning)]
The glass plate cut out according to the above [Amount of foreign matter adhering to the glass plate (before cleaning)] is further washed with water in a shower for 30 seconds under running water of pure water (3 liters / minute) at 20 ° C., and then with a nitrogen blower. It was dried. Next, the adhesion of foreign matter on the glossy surface and the non-glossy surface of the glass plate was visually determined. The evaluation criteria are the same as the above [Amount of foreign matter adhering to the glass plate (before cleaning)].

The sizing agents used in the examples are shown below.
Sizing agent A: Wax compound with SP value of 7.5 (Arakawa Kogyo Co., Ltd. "Size Pine W-116H")
Sizing agent B: Rosin compound with SP value of 8.5 (Misawa Ceramics Co., Ltd. "RF size 880L-50")
Sizing agent C: Rosin compound with SP value of 9.3 ("Size Pine E-50" by Arakawa Chemical Industries, Ltd.)
Sizing agent D: Polyethyleneimine resin with SP value of 9.7 ("Polymin SN" from BSF Japan)
Sizing agent a: Fluorine compound with SP value of 6.2 (“Asahi Guard AG-550” manufactured by Meisei Chemicals Co., Ltd.)
Sizing agent b: Fluorine-based water repellent with SP value of 7.2 (polychlorotrifluoroethylene aqueous dispersion)
Sizing agent c: Polystyrene-acrylic copolymer with SP value of 10.5 ("Polymaron 1308S" from Arakawa Chemical Industries, Ltd.)
Sizing agent d: Polyvinyl alcohol-based resin with an SP value of 23.4 (Kuraray's "Kuraray Poval PVA-117")

The surfactants used in the examples are shown below.
Nonionic surfactant: Fatty acid ester (DF6300 from Seiko PMC)
Cationic surfactant: Polyalkylene polyamine fatty acid epichlorohydrin (Softon P-400 manufactured by Toho Chemical Industry Co., Ltd.)
Anionic surfactant: Sulfuric acid ester (Hitenol LA10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)

[Example 1]
To the raw material pulp of LBKP, 4.5 kg / pulp t of sizing agent A as a sizing agent, 1 kg / pulp t of a nonionic surfactant, and 5 kg / pulp t of a sulfuric acid band were added to obtain a pulp slurry as a raw material. It was. This pulp slurry was made with a long net paper machine, and the wire surface was made a glossy surface (surface) with a Yankee dryer to obtain the glass interleaving paper of Example 1. The basis weight of the glass interleaving paper of Example 1 was 60.0 g / m ² , and the freeness was 530 mL. The Beck smoothness on the front surface was 164 seconds, and the Beck smoothness on the back surface was 7 seconds.

[Examples 2 to 17, Comparative Examples 1 to 6]
The glass interleaving papers of Examples 2 to 17 and Comparative Examples 1 to 6 were obtained in the same manner as in Example 1 except that the types and amounts of the added sizing agents and surfactants were as shown in Table 1. The freeness, basis weight and Beck smoothness (front surface and back surface) of each glass interleaving paper were the same as in Example 1.

[Evaluation]
For each of the obtained glass interleaving papers, the amount of foreign matter adhering to the glass plate was evaluated by the above method. The evaluation results are shown in Table 1.

As shown in Table 1, it can be seen that the glass interleaving paper of each example has less foreign matter adhering to the glass plate, and the adhering foreign matter is also efficiently removed by cleaning.

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 (5)

It has a base paper that is mainly composed of pulp fiber and has a surfactant and a sizing agent inside.
The above pulp fibers consist only of hardwood bleached kraft pulp.
A glass interleaving paper having an SP value of 7 or more and 10 or less of the above sizing agent. The glass interleaving paper according to claim 1, wherein the sizing agent is a rosin-based sizing agent. The glass interleaving paper according to claim 1 or 2, wherein the surfactant is a nonionic surfactant. The pulp fiber is dry pulp,
The glass interleaving paper according to claim 1, claim 2 or claim 3, which is a single glossy paper. Including the step of making a pulp slurry containing pulp fiber as a main component and a surfactant and a sizing agent.
The above pulp fibers consist only of hardwood bleached kraft pulp.
The SP value of the above sizing agent is 7 or more and 10 or less.
The content of the surfactant in the pulp slurry with respect to the pulp fiber is 0.1 kg / pulp t or more and 6 kg / pulp t or less.
A method for producing a glass interleaving paper in which the content of the sizing agent in the pulp slurry with respect to pulp fibers is 3 kg / pulp t or more and 8 kg / pulp t or less.