JP5683180B2 - Moisture-proof paper - Google Patents

Description

  The present invention relates to moisture-proof paper. In particular, the present invention relates to moisture-proof paper suitable for packaging such as PPC (plain paper copy) paper.

  When a copy sheet used for dry copying absorbs moisture, the coefficient of friction increases, and a plurality of copy sheets may overlap and be fed into the copying machine during copying. For this reason, the copy paper is packaged with moisture-proof paper to prevent moisture absorption at the distribution and storage stage. Other than such copy paper, for example, articles that dislike moisture such as metal products are similarly packaged with moisture-proof paper.

  As such moisture-proof paper, conventionally, a paper sheet laminated with polyolefin such as polyethylene or polypropylene as a moisture-proof layer is used. Such a moisture-proof paper is excellent in moisture resistance by having a moisture-proof layer of polyolefin, but the base paper layer and the moisture-proof layer cannot be easily separated and are difficult to recycle. Accordingly, various types of moisture-proof paper that can easily dissolve or disaggregate the moisture-proof layer in water or an alkaline solution have been developed (see Japanese Patent No. 4354661 and Japanese Patent Laid-Open No. 9-6779).

  However, when recycling moisture-proof paper having a moisture-proof layer that can be dissolved or disaggregated, if some moisture-proof layer components remain on the surface of the base paper layer, the quality of the recycled paper will deteriorate. There is a disadvantage that it must be removed, which is very time-consuming. In addition, such a moisture-proof paper has a disadvantage that it is difficult to separate the moisture-proof layer at home or office.

Japanese Patent No. 4354661 JP-A-9-67795

  The present invention has been made in view of these disadvantages. The moisture-proof layer can be easily separated from the base paper layer, and both the base paper layer and the moisture-proof layer can be easily recycled. It is an object of the present invention to provide a moisture-proof paper that does not easily peel off.

The invention made to solve the above problems is
A base paper layer,
A moisture-proof paper comprising a moisture-proof layer made of synthetic resin laminated on one surface side of the base paper layer,
The moisture-proof layer is laminated in a pseudo-adhesive state on the base paper layer by an extrusion lamination method,
A moisture-proof paper, wherein a peel strength between the base paper layer and the moisture-proof layer is 0.02 N / 5 cm or more and 5 N / 5 cm or less.

  In the moisture-proof paper of the present invention, the moisture-proof layer can be laminated on the base paper layer by an extrusion laminating method, thereby improving the moisture-proof property. Since the base paper layer and the moisture-proof layer are laminated in a pseudo-adhesive state with a peel strength of 5 N / 5 cm or less, they can be easily separated by pulling them with human hands. Can be recycled efficiently. Moreover, since it is possible to suppress the moisture-proof layer from being mixed into the separated base paper layer, it is possible to produce high-quality recycled paper by recycling. Furthermore, by setting the peel strength between the base paper layer and the moisture-proof layer to 0.02 N / 5 cm or more, it is possible to suppress the moisture-proof layer from being peeled off from the base paper layer at the time of packaging and transporting the article to be packaged. .

  The tensile strength of the moisture barrier layer is preferably 0.45 kN / m or more and 1.5 kN / m or less. When the tensile strength of the moisture-proof layer is 0.45 kN / m or more, for example, the moisture-proof paper is used as a wrapping paper, and the portion where the moisture-proof layer and the base paper layer are bonded with an adhesive is peeled off and unpacked. In this case, the moisture-proof layer can be peeled off without breaking the base paper layer, and mixing of the adhesive into the base paper layer can be suppressed. Thereby, when the base paper layer is used as a raw material for recycled paper, the mixing of the adhesive into the raw material can be further reduced. Further, when the tensile strength of the moisture-proof layer is 1.5 kN / m or less, the moisture-proof layer is not unnecessarily thick and the moisture-proof paper is easily folded.

  The synthetic resin constituting the moisture-proof paper may include polypropylene. By using polypropylene for the moisture-proof layer, the moisture-proof property of the moisture-proof paper can be further improved. Further, by using polypropylene, it is possible to make the moisture-proof layer more difficult to tear and to further prevent the adhesive from remaining on the base paper layer side.

  In the moisture-proof paper, the synthetic resin has a Vicat softening point of 139 ° C. or higher and 155 ° C. or lower. By using a synthetic resin having a Vicat softening point in the above range for the moisture-proof layer, the peel strength between the base paper layer and the moisture-proof layer can be adjusted to an appropriate range, and it is easy to peel off manually, and the moisture-proof layer is difficult to peel off during use. It can be moisture-proof paper.

  In the moisture-proof paper, the average thickness of the moisture-proof layer is preferably 10 μm or more and 50 μm or less. By setting the thickness of the moisture-proof layer to 10 μm or more, the moisture-proof property and strength of the moisture-proof paper can be further increased. By setting the thickness of the moisture-proof layer to 50 μm or less, the moisture-proof layer does not become thicker than necessary, and the moisture-proof paper is easily folded.

The moisture-proof paper preferably has a moisture permeability of 20 g / (m ² · 24 h) or more and 50 g / (m ² · 24 h) or less. By setting the moisture permeability to 50 g / (m ² · 24 h) or less, it can be used as a wrapping paper for copy paper that requires high moisture resistance. Further, by setting the moisture permeability to 20 g / (m ² · 24 h) or more, the moisture-proof layer does not become thicker than necessary, and the moisture-proof paper is easily folded.

  In the moisture-proof paper, the moisture resistance of the moisture-proof layer is preferably 0.01 or more and 0.8 or less. By setting the static friction coefficient within the above range, generation of static electricity due to friction between moisture-proof paper used as wrapping paper and an article to be packaged can be suppressed.

  In the moisture-proof paper, the paper material constituting the base paper layer may be kraft paper. By making the base paper layer craft paper, the strength of the moisture-proof paper can be further increased.

  Since the moisture-proof paper has the above characteristics, it can be suitably used for packaging PPC paper.

  Here, the “pseudo-bonded state” means that the base paper layer and the moisture-proof layer are bonded in a normal use state, but when peeling both, they are easily peeled off by simply pulling them manually, and simply overlapped. It means a state where it cannot be re-adhered only by pressing. The pseudo-adhesion state is different from the normal lamination with an adhesive material in that it is “a state where it cannot be re-adhered simply by overlapping and pressing”.

  As described above, according to the moisture-proof paper of the present invention, since the base paper layer and the moisture-proof layer can be easily peeled manually, both the base paper layer and the moisture-proof layer can be easily recycled. On the other hand, it is possible to prevent the moisture-proof layer from being peeled off from the base paper layer during packaging or transportation.

It is a cross-sectional schematic diagram of the moisture-proof paper which concerns on one Embodiment of this invention. It is a process schematic diagram which shows one Example of the manufacturing method of the moisture-proof paper of this invention.

  Hereinafter, a moisture-proof paper according to an embodiment of the present invention will be described with reference to the drawings as appropriate. Since the moisture-proof paper of the present invention has a high moisture-proof property, it is preferably used as a wrapping paper for copy paper. As shown in FIG. 1, the moisture-proof paper 1 includes a base paper layer 2 and a moisture-proof layer 3 laminated on one surface side of the base paper layer 2.

  The paper used as the base paper layer 2 is not particularly limited. For example, kraft paper such as unbleached kraft paper, semi-bleached kraft paper, bleached kraft paper, high quality paper, medium quality paper, pure white roll, glassine paper, thermal paper, Examples include pressure-sensitive paper, Japanese paper, synthetic paper, tracing paper, various coated papers, paperboard, and liner paper. Of these, kraft paper is preferred from the viewpoint of strength and economy.

  As the base paper layer 2, either non-recycled paper or recycled paper can be used. When the recycled paper is used, the used paper content of the base paper layer 2 is preferably 5% or more, particularly preferably 30% or more, from the viewpoints of economy and environmental load. On the other hand, from the viewpoint of ensuring the strength of the moisture-proof paper 1, the used paper content of the base paper layer 2 is preferably 50% or less.

The basis weight of the base paper layer 2 is not particularly limited, but is preferably 50 g / m ² or more from the viewpoint of ensuring the strength of the moisture-proof paper 1, and from the viewpoint of ensuring ease of folding and economy at the time of packaging, 100 g / m ² or less is preferable. In the case of using recycled paper having a used paper content of 5% or more and 50% or less as the base paper layer 2, the basis weight is preferably 75 g / m ² or more from the viewpoint of securing the strength of the moisture-proof paper. When non-recycled paper is used as the base paper layer 2, the basis weight is preferably 75 g / m ² or less from the viewpoint of economy and environmental load.

  The synthetic resin used for the moisture-proof layer 3 coated on the base paper layer 2 is not particularly limited. For example, polyethylene, polypropylene, polymethylpentene, ethylene-vinyl acetate resin, ethylene-ethyl acrylate resin, ethylene-acrylic acid. Examples include resins, ethylene-methacrylic acid resins, ethylene-methyl acrylate resins, ionomer resins, polyvinyl alcohol, and polyesters. Among these, polyolefin resins such as polyethylene and polypropylene are preferable from the viewpoint of moisture resistance, and polypropylene is particularly preferable from the viewpoint of ensuring the strength of moisture-proof paper.

  Although it does not specifically limit as a Vicat softening point of the synthetic resin used for the moisture-proof layer 3, 139 degreeC or more and 155 degrees C or less are preferable. When a synthetic resin having a Vicat softening point of less than 139 ° C. is used for the moisture-proof layer, the peel strength between the base paper layer and the moisture-proof layer becomes too high, and the base paper layer and the moisture-proof layer may not be peeled manually. On the other hand, when a synthetic resin having a Vicat softening point exceeding 155 ° C. is used for the moisture-proof layer, the peel strength between the base paper layer and the moisture-proof layer becomes too small, and the moisture-proof layer may be peeled off when the moisture-proof paper is used.

  As a commercial product of the synthetic resin used for the moisture-proof layer 3, as polyethylene, “PES-20 (trade name)”, Nippon Unicar Co., Ltd., “NUC-8505 (trade name)” Nippon Unicar Co., Ltd., “Suntech LDL1850A” (Trade name) “Asahi Kasei Chemicals Co., Ltd.”, “Hedrocene 342 (trade name)” Asahi Kasei Chemicals Co., Ltd., and “FW163 (trade name)” Chisso Co., Ltd. "FW363A (trade name)" Sumitomo Chemical Co., Ltd., "LR510 (trade name)" Showa Denko KK, "LR710-3 (trade name)" Showa Denko KK, "LA 221 (product) Name) "Mitsui Petrochemical Industry Co., Ltd.", "FL25E (Product Name)" Mitsubishi Oil Chemical Co., Ltd., "FL25T (Product Name)" Mitsubishi Oil Chemical Co., Ltd., "MFW2971 (Product) ) "Mitsui Petrochemical Industry Co., Ltd., etc. As ethylene-vinyl acetate," EVA530 (trade name) "Tosoh Corporation," EVA541 (trade name) "Tosoh Corporation," EVA625 (trade name) " “Tosoh Corporation”, “EVA633 (trade name)” Tosoh Corporation. Among these, “FW163 (trade name)” Chisso Corporation, “F3990 (trade name)” Chisso Corporation, “FW363A (trade name)” Sumitomo Chemical Industries whose Vicat softening point is 139 ° C. or higher and 155 ° C. or lower. "LR510 (trade name)" Showa Denko KK, "LR710-3 (trade name)" Showa Denko KK, "LA221 (trade name)" Mitsui Petrochemical Co., Ltd., "FL25E ( (Product name) “Mitsubishi Yuka Co., Ltd.” and “FL25T (product name)” Mitsubishi Yuka Co., Ltd. are preferred. These can be used alone or in combination of two or more.

  The tensile strength of the moisture-proof layer 3 is not particularly limited, but is preferably 0.45 kN / m or more, particularly preferably 0.50 kN / m or more. By setting the tensile strength of the moisture-proof layer to 0.45 kN / m or more, for example, the moisture-proof paper is used as a wrapping paper, and the portion where the moisture-proof layer and the base paper layer are bonded with an adhesive is peeled off and unpacked. In this case, the moisture-proof layer can be peeled off without breaking the base paper layer, and mixing of the adhesive into the base paper layer can be suppressed. Thereby, when the base paper layer is used as a raw material for recycled paper, the mixing of the adhesive into the raw material can be further reduced. Further, the tensile strength of the moisture-proof layer is preferably 1.5 kN / m or less, and particularly preferably 1.0 kN / m or less. By setting the tensile strength to 1.5 kN / m or less, the moisture-proof layer can be prevented from becoming too thick and the moisture-proof paper can be easily folded.

  The tensile strength of the moisture-proof layer 3 is a value obtained by cutting out a test piece having a width of 15 mm and conducting a tensile test based on JIS-P8113 and converting the obtained maximum tensile load into a width of 1 m.

  The moisture-proof layer 3 may contain an ultraviolet absorber. Thereby, when the moisture-proof paper is used as a wrapping paper for copy paper, discoloration of the copy paper due to ultraviolet rays can be suppressed.

  Further, the moisture-proof layer 3 may contain an antistatic agent. As a result, when the moisture-proof paper is used as a wrapping paper for copy paper, the copy paper can be prevented from being charged, and double feeding when using the copy paper in the copying machine can be suppressed.

  The tear strength of the moisture-proof layer 3 is not particularly limited, but is preferably 5N or more, particularly preferably 10N or more. When the tear strength of the moisture-proof layer 3 is in the above range, the moisture-proof layer 3 is difficult to tear in the middle of peeling the moisture-proof layer 3 from the base paper layer 2, so that the moisture-proof layer 3 is easily peeled from the base paper layer 2. Further, the tear strength of the moisture-proof layer 3 is preferably 20 N or less, and particularly preferably 15 N or less. By making the tear strength of the moisture-proof layer 3 within this range, it is possible to ensure the economics of the moisture-proof paper and to make the packaging easy by suppressing the thickness of the moisture-proof paper.

  The tear strength of the moisture-proof layer 3 is based on JIS-K7128-2, with a 20 mm notch perpendicular to the long side of the 75 mm × 63 mm rectangular test piece cut out from the moisture-proof layer 3. Is a value measured by an Elmendorf tear tester.

  Although it does not specifically limit as a minimum of the average thickness of the moisture-proof layer 3, It is preferable to set it as 10 micrometers from a viewpoint of ensuring required intensity | strength and moisture-proof property when using as moisture-proof paper. The upper limit of the thickness of the moisture-proof layer 3 is preferably 50 μm from the viewpoints of pressing the moisture-proof paper to a certain thickness and ensuring ease of packaging and from the viewpoint of economy.

  The static friction coefficient of the moisture-proof layer 3 is not particularly limited, but is preferably 0.01 or more and 0.8 or less, and particularly preferably 0.01 or more and 0.6 or less. By making a static friction coefficient into the said range, generation | occurrence | production of the static electricity by the friction with the moisture-proof paper 1 used as a wrapping paper and a to-be-packaged object can be suppressed.

  The coefficient of static friction of the moisture-proof layer 3 is a value measured by superimposing the surfaces of the moisture-proof layer 3 on the basis of JIS-K7125.

  The base paper layer 2 and the moisture-proof layer 3 are in a pseudo-adhesive state. The peel strength between the base paper layer 2 and the moisture-proof layer 3 is required to be 5 N / 5 cm or less and is preferably 4 N / 5 cm or less from the viewpoint of easy peeling of the moisture-proof layer 3 from the base paper layer 2. . The peel strength is required to be 0.02 N / 5 cm or more and 0.05 N / 5 cm or more from the viewpoint of making it difficult to peel the moisture-proof layer 3 from the base paper layer 2 during packaging and transportation. preferable.

  The measurement of the peel strength is performed using a test piece cut from the moisture-proof paper 1 into a width of 50 mm and a length of 200 mm and conditioned according to JIS-P8111. Adhere the side of the base paper layer 2 of this test piece to the metal plate with double-sided tape, set the metal plate so that the length direction of the test piece is vertical, and peel off the moisture-proof layer 3 on the lower part of the test piece. Wind up and chuck. The chucked portion is pulled upward at 300 mm / min to proceed with peeling, the stress during this period is measured, and the average value of this stress is taken as the peeling strength.

The moisture permeability of the moisture-proof paper 1 is not particularly limited, but is preferably 20 g / (m ² · 24 h) or more and 50 g / (m ² · 24 h) or less. If the moisture permeability is 50 g / (m ² · 24 h) or less, it can be suitably used as a wrapping paper for copy paper that requires high moisture resistance. As a result, when using copy paper in a copying machine, copy paper Double feeding due to moisture absorption can be suppressed. Further, by setting the moisture permeability to 20 g / (m ² · 24 h) or more, the moisture-proof layer does not become thicker than necessary, and the moisture-proof paper is easily folded.

  The moisture-proof paper has excellent moisture resistance and recyclability as described above, and can be used for packaging of various products. The moisture-proof paper can be suitably used for packaging of PPC paper that is particularly required to be moisture-proof and has a large amount of use and a high demand for recycling.

(Method of manufacturing the moisture-proof paper)
The moisture-proof paper is manufactured by an extrusion laminating method. In order to obtain a good pseudo-adhesive state, the moisture-proof layer 3 is laminated on the base paper layer 2 by an extrusion laminating method. Hereinafter, the moisture-proof paper manufacturing method will be described with reference to FIG. In FIG. 2, the pressing roll 11 and the cooling roll 12 are disposed opposite to each other at both sides of the T die 10 vertically below. The base paper layer 2 is supplied between the pressure roll 11 and the cooling roll 12 from a feed roll (not shown). The molten resin 13 extruded from the T die 10 is supplied between the pressure roll 11 and the cooling roll 12 so as to overlap the upper side of the base paper layer 2. In this way, the base paper layer 2 and the molten resin 13 are pressure-bonded between the pressure-bonding roll 11 and the cooling roll 12 to be in a pseudo-bonded state, thereby forming the moisture-proof paper 1. The formed moisture-proof paper 1 is taken up by a take-up roll (not shown) through a guide roll 14.

  The thickness of the moisture-proof layer 3 can be appropriately adjusted by the extrusion temperature and extrusion speed of the molten resin, the feed speed of the base paper layer 2, the pressure applied between the pressure-bonding roll 11 and the cooling roll 12, and the like.

  Further, the peel strength of the moisture-proof layer 3 can be adjusted mainly by the extrusion temperature of the molten resin 13. Although this extrusion temperature is not specifically limited, 180 to 340 degreeC is preferable from a viewpoint of obtaining a more favorable pseudo-adhesion state. When the moisture-proof layer 3 is polyethylene, it is preferably 180 ° C. or higher and 280 ° C. or lower, and particularly preferably 190 ° C. or higher and 210 ° C. or lower. When the moisture-proof layer 3 is polypropylene, 270 ° C. or higher and 340 ° C. or lower is preferable, and 310 ° C. or higher and 330 ° C. or lower is particularly preferable.

  Although it does not specifically limit as the cooling roll 12 used in the case of extrusion lamination, In order to obtain the pseudo-adhesion state of the base paper layer 2 and the moisture-proof layer 3, what gave the surface of the cooling roll 12 a semi mirror finish, or a mirror It is preferable to use a finishing roll, and it is more preferable to use a cooling roll 12 having a mirror finish.

  The method for adjusting the peel strength between the base paper layer 2 and the moisture-proof layer 3 is not limited to the method for selecting the type of finish on the surface of the cooling roll 12 and the method for adjusting the extrusion temperature of the moisture-proof layer 3, and various methods are available. Can be used. For example, a method of adjusting the lamination pressure of the resin for the moisture-proof layer 3 to be extruded and the base paper layer 2, a method of selecting the material of the moisture-proof layer 3 and the base paper layer 2, and the like can be mentioned.

  Hereinafter, the present invention will be described in detail based on examples.

(Example 1)
The moisture-proof paper of Example 1 was produced by laminating a moisture-proof layer on the base paper layer by the extrusion lamination method under the following conditions. The production conditions were set so that the moisture-proof layer had a thickness of 15 μm.
-Base paper layer: unbleached kraft paper (basis weight 70 g / m ² )
-Moisture-proof layer material: Polypropylene ("FW163" manufactured by Chisso Corporation)
-Cooling roll: mirror finish-Extrusion temperature: 340 ° C

(Examples 2 to 5 and Comparative Examples 1 and 2)
Except that the production conditions were as described in Table 1, moisture-proof papers of Examples 2 to 5 and Comparative Examples 1 and 2 were obtained by the extrusion laminating method in the same manner as in Example 1. The production conditions were set so that the average thickness of the moisture-proof layer was the value shown in Table 1. In addition, “PES-20” manufactured by Nippon Unicar Co., Ltd. was used for the polyethylene of Example 4, and “EVA541” manufactured by Tosoh Corporation was used for the ethylene-vinyl acetate resin of Example 5.

(Comparative Example 3)
A commercially available polyethylene laminated paper in which a polyethylene moisture-proof layer was laminated on the base paper layer by a dry lamination method was used as the moisture-proof paper of Comparative Example 3.

(Comparative Example 4)
The applicant's product “Tokebara (trade name)” in which a water dissociable moisture-proof layer was formed on the base paper layer by a coating method was used as the moisture-proof paper of Comparative Example 4.

<Evaluation>
The following various evaluations were performed on the moisture-proof papers of the examples and comparative examples by the following methods.

(Average thickness of moisture barrier)
The cross sections of the moisture-proof papers of Examples 1 to 5 and Comparative Examples 1 to 3 were observed using an optical microscope, the thickness of the moisture-proof layer was measured at 10 locations, and the arithmetic average of the measured values was the average thickness of the moisture-proof layer. Say it.

(Peeling strength between base paper layer and moisture-proof layer)
Test pieces having a width of 50 mm and a length of 200 mm were cut from the moisture-proof papers of Examples 1 to 5 and Comparative Examples 1 and 2. According to JIS-P8111, this test piece was kept in a room adjusted to a room temperature of 23 ° C. and a humidity of 50% for 24 hours to adjust the humidity. Adhere one side of this test piece to the metal plate with double-sided tape, set the metal plate so that the length direction of the test piece is in the vertical direction, peel off the moisture-proof layer on the lower part of the test piece and wind up I chucked. The chucked portion was pulled upward at 300 mm / min to proceed with peeling, and the stress during this time was measured. The average value of this stress was taken as the peel strength.

(Tensile strength)
From the moisture-proof layer peeled off from the moisture-proof paper of Examples 1 to 5 and Comparative Examples 1 and 2, a test piece having a width of 15 mm was cut out based on JIS-P8113, and a tensile test was performed. The value obtained by converting the obtained maximum tensile load into a width of 1 m was taken as the tensile strength.

(Breathable)
The moisture permeability test of the moisture-proof papers of Examples 1 to 5 and Comparative Examples 1 to 4 was performed according to the following procedure based on the method B of JIS-Z0208. A circular test piece having a diameter of 70 mm was cut out from each moisture-proof paper, and a portion having a diameter of 60 mm at the center of the test piece was taken as a measurement range. This was set in a moisture permeable cup containing calcium chloride with the moisture-proof layer on the outside, and the periphery was sealed with a sealant. This moisture permeable cup was placed in a thermostatic chamber, adjusted to a temperature of 40 ° C. and a humidity of 90%, and held for 24 hours. The moisture permeable cup was taken out into a room adjusted to a room temperature of 23 ° C. and a humidity of 50%, and its mass was measured with an analytical balance. The moisture permeable cup was returned to the constant temperature and humidity chamber and further maintained for 24 hours, and then the mass of the moisture permeable cup was measured again. The increased mass of the moisture permeable cup was calculated from these two mass measurements, and the moisture permeability was calculated from the following formula (1).
Moisture permeability = 240 × M / (T × S) (unit: (g / m ² · 24 h)) (1)
S: Moisture permeable area (cm ² )
T: Time during which the moisture permeable cup was held in the constant temperature and humidity chamber (= 24 h)
M: Mass of moisture permeable cup (mg)

(Static friction coefficient test)
Using the test pieces collected from the moisture-proof papers of Examples 1 to 5 and Comparative Examples 1 and 2, the static friction coefficient of each moisture-proof paper was measured based on JIS-K7175 with the moisture-proof layers overlapped.

(Easy separation of moisture barrier)
Using the test pieces cut out from the moisture-proof papers of Examples 1 to 5 and Comparative Examples 1 and 2 to 50 cm × 50 cm, the base paper layer and the moisture-proof layer were peeled off manually to examine the ease of separation of the moisture-proof layer. “○” indicates that one of the base paper layer or the moisture-proof layer does not remain on the other side by visual inspection, and “X” indicates that one of the base paper layer or the moisture-proof layer remains on the other side even a little. did.

(Peeling resistance during transportation)
Exfoliation resistance at the time of conveyance was investigated using what was cut out from the moisture-proof paper of Examples 1-5 and Comparative Examples 1 and 2 as a wrapping paper. A package of 500 sheets of A4 copy paper was grasped with both hands and vibrated vigorously 100 times vertically and horizontally. After such vibrations, “◯” indicates that the moisture-proof layer was not peeled off from the base paper layer at all, and “X” indicates that the moisture-proof layer was peeled off even slightly from the base paper layer.

(Easy removal of adhesive)
The moisture-proof layer surface and the base paper layer surface of the test pieces cut out from Examples 1 to 5 and Comparative Examples 1 and 2 were bonded with a hot melt adhesive for packaging copy paper. The moisture-proof layer around the bonded portion was pulled to examine the ease of removal of the adhesive from the base paper layer. The case where the adhesive was peeled off from the base paper layer due to tearing of the base paper layer or the like, and the case where the moisture-proof layer was broken and the adhesive remained on the base paper layer 2 was indicated as “x”.

  Table 1 shows production conditions and evaluation results.

  From the results in Table 1, it was shown that the moisture-proof layer by the extrusion laminating method is superior in moisture permeability compared to the moisture-proof layer by other manufacturing methods. The peel strength between the base paper layer and the moisture-proof layer should be above a certain value so that the moisture-proof layer does not peel off from the base paper layer during transportation of the packaged article. In order to be able to peel off, it can be said that it is necessary to be below a certain value. In order to easily remove the adhesive from the base paper layer, it can be said that the tensile strength of the moisture-proof layer is also preferably a certain value or more.

  As described above, the moisture-proof paper of the present invention can easily peel off the base paper layer and the moisture-proof layer by hand, so that a wrapping paper such as PPC paper that can easily recycle both the base paper layer and the moisture-proof layer is used. Can be provided.

1 Moisture-proof paper
2 Base paper layer 3 Moisture-proof layer 10 T die 11 Pressure bonding roll 12 Cooling roll 13 Molten resin 14 Guide roll

Claims (7)

A base paper layer,
A moisture-proof paper comprising a moisture-proof layer made of synthetic resin laminated on one surface side of the base paper layer,
The paper material constituting the base paper layer is kraft paper,
The moisture-proof layer is laminated in a pseudo-adhesive state on the base paper layer by an extrusion lamination method,
Ri der peel strength 0.02 N / 5 cm or more 5N / 5 cm or less between the base paper layer and the moisture-proof layer,
The moisture- proof paper, wherein the moisture- proof layer has a tensile strength of 0.45 kN / m or more and 1.5 kN / m or less . The moisture-proof paper according to claim 1 , wherein the synthetic resin contains polypropylene. The moisture-proof paper according to claim 1 or 2 , wherein the synthetic resin has a Vicat softening point of 139 ° C or higher and 155 ° C or lower. The moisture-proof paper according to claim 1 , wherein the moisture-proof layer has an average thickness of 10 μm or more and 50 μm or less. The moisture-proof paper according to any one of claims 1 to 4 , wherein the moisture permeability is 20 g / (m ² · 24h) or more and 50 g / (m ² · 24h) or less. The moisture-proof paper according to any one of claims 1 to 5 , wherein the moisture-proof layer has a static friction coefficient of 0.01 or more and 0.8 or less. The moisture-proof paper according to any one of claims 1 to 6 , which is used for packaging PPC paper.

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