Paper tube manufacturing and method for observing changes in paper tube manufacturing due to environmental changes

Abstract

The absorption and discharge of moisture from the outer surface of the paper tube is left to the user to wind onto the material after delivery, and the above configuration suppresses the discharge and absorption of moisture from the inner surface of the paper tube, thereby reducing the occurrence of wrinkles in the winded material after delivery, and also suppresses the expansion of the outer diameter of the paper tube due to moisture absorption, thereby reducing the occurrence of deformation such as steps on the outer surface of the paper tube. [Solution] The present invention relates to a paper tube winding core 1 for winding a sheet-like material onto its outer surface, comprising a paper tube 2 and a moisture-proof sheet 3, wherein the moisture-proof sheet 3 is provided on the inner surface side of the paper tube 2, thereby suppressing the evaporation of moisture from the paper tube 2 from the inner surface 21 to the outside of the paper tube 2 and the absorption of moisture from the outside of the paper tube 2 through the inner surface 21 of the paper tube 2.

Description

Technical Field

[0001] The present invention relates to a paper tube core for paper tubes and a method for observing changes in the paper tube core associated with environmental changes.

Background Art

[0002] In the paper tube manufacturing industry, in order to prevent the occurrence of blocking due to the transfer of moisture from the paper tube side to the wound objects such as water-absorbent nylon films and papers wound around the paper tube (paper tube core) by users such as film manufacturers, the destination of the paper tube after shipment, and to further prevent the occurrence of dimensional changes and warping of the paper tube due to environmental changes at the destination after the paper tube is shipped, a moisture-proof sheet (moisture-proof sheet) is arranged on the outer peripheral surface side (upper layer side) of the paper tube to block the transfer of moisture from the paper tube side to the wound object (Patent Documents 1 and 2).

[0003] However, despite the above-mentioned device, there have been reports from users of the paper tube that wrinkles have occurred in the above-mentioned wound objects. Paper tube manufacturers usually acclimatize the paper tube (paper tube core) to the natural environment for several days, that is, after curing, the moisture-proof sheet is arranged on the outer peripheral surface side of the paper tube. Therefore, it is difficult to consider the transfer of moisture from the paper tube (paper tube core) to the wound object. For many paper tube manufacturers, the dominant perception is that the occurrence of the above-mentioned wrinkles is due to the inappropriate winding method of the user of the wound object onto the paper tube, and generally the cause of the occurrence of wrinkles is attributed to the user side of the paper tube.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, after hearing from users, the inventor of this invention learned that users were taking sufficient care in winding the material onto the paper tubes. As a paper tube manufacturer, the inventor thought it would be premature to dismiss the occurrence of the wrinkles as being due to improper winding by the users, as other paper tube manufacturers have done. Therefore, after diligent research, the inventor of this invention discovered that after delivery to the user, moisture evaporates from the inner surface of the paper tube, causing the diameter of the paper tube to shrink and wrinkle the wound material. Furthermore, it was discovered that when paper tubes are delivered after being thoroughly dried, the moisture absorbed by the paper tube from the inner circumferential surface after delivery causes the diameter of the area on the outer circumferential surface of the paper tube to expand relative to the area on the tube end where the material is not wound, relative to the area on the tube end where the material is wound (the area where the diameter cannot expand due to being tightened by the material) in the axial center, creating a step between the two areas. The inventor, through his unconventional thinking, concluded that, regarding paper tube cores, since the discharge and absorption of moisture from the outer surface of the paper tube is suppressed by the material wound onto it by the user after delivery, it would be more appropriate to suppress the discharge and absorption of moisture from the inner surface of the paper tube rather than the outer surface. Based on the above findings, the inventors have attempted to suppress the occurrence of wrinkles in the material wound on a paper tube core by changing their approach. [Means for solving the problem]

[0006] The present invention provides a paper tube winding core for winding a sheet-like material onto its outer surface, comprising a paper tube and a moisture-proof sheet, wherein the moisture-proof sheet is provided on the inner surface side of the paper tube, thereby suppressing the evaporation of moisture from the inner surface of the paper tube to the outside of the paper tube and the absorption of moisture from the outside of the paper tube through the inner surface of the paper tube. Furthermore, in the present invention, the inner circumferential surface side of the paper tube is defined as a position not exceeding 30% of the thickness of the paper tube from the inner circumferential surface toward the outer circumferential surface of the paper tube, and the moisture-proof sheet is not provided on the outer circumferential surface side of the paper tube, i.e., in the range not exceeding 70% of the thickness of the paper tube from the outer circumferential surface toward the inner circumferential surface of the paper tube. The moisture-proof sheet provides a paper tube core with a moisture permeability of 25 g / m²·24 hours or less when placed in an environment of 40 degrees Celsius and 90 percent relative humidity for 24 hours. Furthermore, in the present invention, the paper tube is formed by spirally laminating multiple strip-shaped paper tapes, with the outer surface of the paper tube being the upper layer of the laminated paper tapes and the inner circumferential surface of the paper tube being the lower layer of the laminated paper tapes, and the moisture-proof sheet is a moisture-proof sheet such as aluminum sandpaper formed in a strip shape, and the moisture-proof sheet is placed on the bottom layer in place of the bottommost paper tape among the multiple paper tapes, placed on the layer immediately above the bottommost paper tape, or placed on the upper layer with one or two pieces of paper tape sandwiched between it and the bottommost paper tape, thereby providing a paper tube winding core in which the moisture content of the paper tube does not exceed 8 percent. The moisture-proof sheets described above, such as aluminum sandpaper, include sheets such as aluminum sandpaper, moisture-proof transparent vapor-deposited barrier film sheets, moisture-proof barrier film sheets, moisture-proof aluminum vapor-deposited film sheets, poly-sand kraft paper, and paper-based moisture-proof materials. Paper-based moisture-proof materials refer to paper such as kraft paper, neutral paper, liner, or paper tube base paper to which a resin has been applied as a moisture-proof coating agent. Here, it specifically refers to paper to which an appropriate amount of moisture-proof coating agent (resin) has been applied to function as a moisture-proof sheet. The aluminum sandpaper described above is a sheet to which paper such as kraft paper is laminated to both sides of aluminum foil with a well-known adhesive or a resin such as polyethylene. The resin such as polyethylene includes polypropylene, polyethylene terephthalate, and polybutylene terephthalate in addition to polyethylene. The paper such as kraft paper described above includes liner and paper tube base paper in addition to kraft paper. Furthermore, the paper such as kraft paper described above also includes neutral paper other than kraft paper, liner, and paper tube base paper. The above-mentioned transparent vapor-deposited barrier film is a film in which a barrier material such as aluminum oxide is vapor-deposited onto a base material such as polyester. The above-mentioned base material such as polyester includes, in addition to those based on polyester, polyamide, nylon, polypropylene, polyethylene, or polystyrene. The above-mentioned barrier material such as aluminum oxide includes, in addition to those based on aluminum oxide (alumina), silica. The above-mentioned barrier film is a film in which a top coat treatment, i.e., a moisture-proof coating such as acrylic, is applied to the surface of the above-mentioned transparent vapor-deposited barrier film. The above-mentioned moisture-proof coating such as acrylic includes, in addition to acrylic, polyurethane, copolymer (acrylate polyurethane), or silicone. The above-mentioned aluminum vapor-deposited film is a film material such as polyethylene terephthalate on which aluminum is vapor-deposited. The above-mentioned film material such as polyethylene terephthalate includes, in addition to polyethylene terephthalate film, films such as unoriented polypropylene, biaxially oriented polypropylene, polyethylene, cellophane, or paper.The above-mentioned polysand kraft paper is made by laminating kraft paper or other paper to a base paper using an adhesive and a resin such as polyethylene. The kraft paper and other papers include neutral papers other than kraft paper, liner, and paper tube base paper. In addition to polyethylene, the above-mentioned resins such as polyethylene include polypropylene, polyethylene terephthalate, and polybutylene terephthalate. Furthermore, the present invention provides a method for observing changes in a paper tube core due to environmental changes, by attaching a pressure sensor to the outer surface of the paper tube core, observing the changes in pressure applied to the outer surface of the paper tube core in response to changes in the temperature and humidity of the environment in which the paper tube core is placed, and investigating the effect on the paper tube core, such as a change in the diameter of the paper tube core. Furthermore, the present invention provides a method for observing changes in a paper tube core according to claim 1 in response to environmental changes, by attaching a pressure sensor to the outer surface of the paper tube core and investigating the effect on the paper tube core due to the expansion and contraction of the object being wound in response to changes in the temperature and humidity of the environment in which the object being wound is placed. [Effects of the Invention]

[0007] This invention relates to a paper tube core, in which the absorption and discharge of moisture from the outer surface of the paper tube is left to the material wound by the user after delivery, and the discharge and absorption of moisture from the inner surface of the paper tube is suppressed with the above configuration, thereby suppressing the shrinkage of the outer diameter of the paper tube due to moisture discharge and reducing the occurrence of wrinkles in the material wound by the paper tube core after delivery. Furthermore, the expansion of the outer diameter of the paper tube due to moisture absorption is suppressed, thereby reducing the occurrence of deformation such as steps on the outer surface of the paper tube. In particular, the present invention (Claim 4) makes it possible to accurately grasp the effect of changes in temperature and humidity of the paper core after manufacturing on the paper core, which can cause wrinkles in the material being wound and deformation of the paper core, by measuring the pressure applied to the outer surface of the paper core. Furthermore, the present invention (claim 5) makes it possible to accurately grasp the effect of the expansion and contraction of the material being wound on the paper tube core due to changes in temperature and humidity in the environment in which the material is placed, by measuring the pressure applied to the outer surface of the paper tube. [Brief explanation of the drawing]

[0008] [Figure 1] (A) is a schematic end view of a paper tube constituting a paper tube winding core according to the present invention, and (B) is a schematic end view of a paper tube winding core in which a moisture-proof sheet is provided on the paper tube of (A). [Figure 2] (A) is a partially cutaway schematic side view showing one step in the manufacturing process of the paper tube core shown in Figure 1(B), and (B) is a partially cutaway schematic perspective view of the paper tube core formed through the manufacturing process of (A). [Figure 3] (A) is a schematic side view of a paper tube core showing a method for measuring the pressure exerted on the paper tube core by the material being wound (film) (arrangement of pressure sensors when using one pressure sensor), (B) is a schematic end view of the paper tube core in (A), and (C) is a front view showing a temperature and humidity measuring instrument used for temperature and humidity measurement performed together with the pressure measurement in (A). [Figure 4] (A) shows a schematic side view of a paper tube core illustrating a method for measuring the pressure exerted on the paper tube core by the material being wound (film) (arrangement of pressure sensors when using 8 pressure sensors), and (B) shows a schematic end view of the paper tube core shown in (A). [Figure 5] (A) is a side view (photograph) of a paper tube core with the pressure sensor shown in Figure 3 attached, and (B) is a partially cutaway perspective view (photograph) of a paper tube core during pressure measurement, as shown in Figure 3. [Figure 6] (A) is an explanatory diagram (graph) showing the relationship between the temperature, humidity, and pressure applied to a conventional paper tube winding core without a moisture-proof sheet, measured using the apparatus shown in Figures 3 and 5. (B) is a plan view (photograph) of the film wound onto the paper tube winding core from which the graph in (A) was taken. [Figure 7] Figures 3 to 6 show explanatory diagrams (graphs) illustrating the changes in temperature, humidity, and water vapor content over time in the environment (constant temperature room) where the paper tube core is placed during measurement using the methods and means shown. [Figure 8](A) is a schematic perspective view of a paper tube core showing the outer diameter and the moisture measurement positions, (B) is a schematic longitudinal sectional view of a paper tube core showing the measurement positions of the comparative example, (C) is a schematic longitudinal sectional view of a paper tube core showing the measurement positions of the example, (D) is a schematic sectional view showing the moisture movement of a paper tube core without a moisture-proof sheet (moisture-proof material) around which the winding object is wound, (E) is a schematic sectional view showing the moisture movement of a paper tube core with a moisture-proof sheet (moisture-proof material) around which the winding object is wound [Figure 9] An explanatory diagram (photo) showing the size of the wrinkles generated at one end of each of the (roll-shaped) films wound around each of the paper tube cores which are the comparative example and the example. [Figure 10] An explanatory diagram (photo) showing the state of being unwound from the paper tube core for confirmation of wrinkle generation for each film in Fig. 9. [Figure 11] An explanatory diagram (photo) showing the vicinity of both ends of the film in the width direction of the film orthogonal to the longitudinal direction with the axial direction of the paper tube as the longitudinal direction for each film in Fig. 10. [Figure 12] An explanatory diagram showing graphs of the relationship between moisture and the outer diameter of the paper tube at each position near both tube ends of the paper tube and at the center in the axial direction of the paper tube for each of the paper tube cores with different moisture contents which are the comparative example. [Figure 13] An explanatory diagram showing graphs of the relationship between moisture and the outer diameter of the paper tube at each position near both tube ends of the paper tube and at the center in the axial direction of the paper tube for each of the paper tube cores with different moisture contents which are the example. [Figure 14] An explanatory diagram showing graphs of the relationship between moisture and the outer diameter of the paper tube at each position near both tube ends of the paper tube and at the center in the axial direction of the paper tube for each of the paper tube cores with different moisture contents which are the example. [Figure 15] An explanatory diagram showing graphs of the change in the pressure applied to the surface of the paper tube core over time for each of the paper tube cores which are the comparative example and the example. [Figure 16] An explanatory diagram extracted from the graph shown in Fig. 15, which is the graph of the comparative example. [Figure 17] An explanatory diagram extracted from the graph shown in Fig. 15, which is the graph of the example. [Figure 18] [[ID=~30]]An explanatory diagram extracted from the graph shown in Fig. 15, which is the graph of the example. [Figure 19] (A) is an explanatory drawing showing an image of a film in a deployed state with wrinkles across the entire width, (B) is an explanatory drawing showing an actual photograph of the film in (A), (C) is an explanatory drawing showing an image of a film in a deployed state with wrinkles near both ends of the film in the axial direction of the paper tube, and (D) is an explanatory drawing showing an actual photograph of the film in (C).

Embodiments for Carrying out the Invention

[0009] Hereinafter, preferred embodiments of the present invention will be described based on the drawings. (Configuration of the paper tube core 1) This paper tube core 1 includes a paper tube 2 (shown by a dashed line in Fig. 1(A)) that winds a sheet-like winding object around its outer peripheral surface, and a moisture-proof sheet 3 (shown by a dashed line in Fig. 1(B)). [[ID=1,5]]In this example, the paper tube 2 is formed in the shape of a hollow cylinder, that is, a cylindrical shape. Note that the paper tube 2 may be formed in the shape of a hollow prism, that is, a square tube shape. For example, the paper tube 2 may be a cylindrical body with a square cross-section when viewed from the end face.

[0010] The moisture-proof sheet 3 is a sheet having moisture-proof properties and is arranged on the inner peripheral surface side of the paper tube 2 in the radial direction r of the paper tube 2. That is, the moisture-proof sheet 3 is provided on the paper tube 2 closer to the inner peripheral surface 21 of the paper tube 2 than the outer peripheral surface 22 of the paper tube 2. More preferably, the above-mentioned inner peripheral surface side of the paper tube 2 is a position within a range a1 that does not exceed 30% of the thickness of the paper tube 2 from the inner peripheral surface 21 to the outer peripheral surface 22 of the paper tube 2 in the radial direction r of the paper tube 2, and the moisture-proof sheet 3 is inserted (arranged) at this position. In Figs. 1(A) and (B), o indicates the central axis (virtual axis) of the cylindrical paper tube 2.

[0011] The moisture-proof sheet 3 may cover the inner peripheral surface 21 of the paper tube 2, but it is desirable to arrange it on the outer peripheral surface side of the paper tube 2 in the radial direction r of the paper tube 2 rather than on the inner peripheral surface 21 of the paper tube 2. This is to reduce the risk of damage to the moisture-proof sheet 3 due to contact between the moisture-proof sheet 3 and the above-mentioned manufacturing apparatus by avoiding the arrangement of the moisture-proof sheet 3 on the inner peripheral surface of the paper tube 2 that comes into direct contact with the manufacturing apparatus (mandrel) of the paper tube during the manufacture of the paper tube core 1.

[0012] On the other hand, the moisture-proof sheet 3 is not provided in the area a2 from the outer surface 22 of the paper tube 2 toward the inner surface 21 of the paper tube 2, in a range not exceeding 70% of the thickness of the paper tube 2. This is to allow moisture to be quickly discharged (evaporated) from the paper tube 2 through the outer surface 22 of the paper tube 2 before shipment of the paper tube core 1.

[0013] For the moisture-proof sheet 3 used in the paper tube core 1, it is best to select one that has a moisture permeability of 25 g / m²·24 hours or less when placed in an environment of 40 degrees Celsius and 90 percent relative humidity for 24 hours. Aluminum sandpaper is the most suitable material for moisture barrier sheet 3. Aluminum sandpaper is a sheet made by laminating paper, such as kraft paper, to both sides of aluminum foil with a well-known adhesive and / or a molten resin such as polyethylene. In this example, the aluminum sandpaper used for moisture barrier sheet 3 is a sheet made by laminating kraft paper to both sides of aluminum foil with molten polyethylene. In addition to polyethylene, polypropylene, polyethylene terephthalate, or polybutylene terephthalate can be used as the molten resin. In addition to kraft paper, liners or core paper can be used as the paper laminated to the aluminum foil mentioned above. Furthermore, neutral paper other than kraft paper, liners, and core paper may also be used as the paper laminated to the aluminum foil.

[0014] In addition to the aluminum sandpaper mentioned above, moisture barrier sheet 3 can also be made of a transparent vapor-deposited barrier film, a barrier film, an aluminum vapor-deposited film, polysand kraft paper, or a paper-based moisture barrier material. A paper-based moisture barrier material is made by applying a moisture barrier coating to paper such as kraft paper, neutral paper, liner, or paper tube base paper, and in this invention, it refers to paper to which a sufficient amount of resin is applied to function as a moisture barrier sheet (to impart moisture barrier performance). Specifically, kraft paper, neutral paper, liner, or paper tube base paper to which a moisture barrier coating (resin) is applied so that the moisture permeability does not exceed 25 g / m²·24 hours can be used as a paper-based moisture barrier material. Furthermore, the transparent vapor-deposited barrier film described above is a film in which a barrier material such as aluminum oxide is vapor-deposited onto a base material such as polyester. In addition to polyester, the base material such as polyester can be polyamide, nylon, polypropylene, polyethylene, or polystyrene. In addition to aluminum oxide (alumina) as the barrier material, silica can be used as the barrier material.

[0015] The barrier film described above is a film in which a topcoat treatment, i.e., a moisture-proof coating such as acrylic, is applied to the surface of the transparent vapor-deposited barrier film described above. In addition to acrylic, the moisture-proof coating can be made of polyurethane, copolymer (acrylate polyurethane), or silicone. The above-mentioned aluminum-metallized film is obtained by depositing aluminum onto a film material such as polyethylene terephthalate. In addition to polyethylene terephthalate, other films such as unoriented polypropylene, biaxially oriented polypropylene, polyethylene, or cellophane can be used as the film material, and paper may also be used.

[0016] The above-mentioned polysand kraft paper is made by laminating another kraft paper onto a base kraft paper using a well-known adhesive and / or by melting a resin such as polyethylene. In addition to the kraft paper mentioned above, other papers such as liner paper or paper tube base paper can be used, and furthermore, neutral papers other than the kraft paper, liner paper, and paper tube base paper can also be used. In addition, polypropylene, polyethylene terephthalate, or polybutylene terephthalate can be used as the resin other than polyethylene.

[0017] (Manufacturing method for paper tube core 1) The paper tube core 1 according to the present invention can be manufactured using a well-known general method for manufacturing paper tubes. For example, the present invention can be implemented in a spiral paper tube (Figure 2(B)) in which multiple strip-shaped paper tapes are layered spirally, and the paper tube core according to the present invention can be manufactured using a well-known method for manufacturing spiral paper tubes (Figure 2(A)). In a spiral paper tube, multiple paper tapes 20 are wound diagonally around a cylindrical rod called a mandrel m with respect to the direction in which the mandrel m extends.

[0018] Of the paper tapes 20, all paper tapes 20 except for the paper tape 20 (20a) that contacts the mandrel m have a well-known adhesive (water-soluble emulsion adhesive) applied to one side facing the mandrel m, and the paper tapes 20 are overlapped with a offset relative to the direction in which the mandrel m stretches. A pair of pulleys p are positioned next to the mandrel m, with an annular belt b stretched over both pulleys p. Between the two pulleys p, a portion (one section) of the annular belt b is passed to both pulleys p in a twisted state and wrapped around the outer surface of the mandrel m. The annular belt b circulates due to the rotation of the pulleys p, which are driven by a power source such as an electric motor (not shown).

[0019] As each strip of paper tape 20, which is wound spirally around the mandrel m with appropriate tension applied without any slack, passes between the two pulleys p, it is pressed down by the belt b and securely bonded to itself with the adhesive, forming a cylindrical paper tube 2. As shown in Figure 2(A), a strip of moisture-proof sheet 3 (the tape with spots in Figure 2(A)) coated with adhesive is placed directly on top of the bottom layer of paper tape 20 (20a) that forms the inner surface of the paper tube 2 after its formation, in place of the other paper tapes 20, and is bonded to the bottom layer of paper tape 20a with adhesive.

[0020] Furthermore, another paper tape 20 may be wrapped around the position of the moisture-proof sheet 3 (tape 30) in Figure 2(A), and the tape 30 designated as the moisture-proof sheet 3 may be superimposed on the other paper tape 20 (instead of the paper tape 20b in Figure 2(A)). Additionally, a paper tape 20 may be wrapped around the position of the tape 30 designated as the moisture-proof sheet 3 in Figure 2(A), and the tape 30 designated as the moisture-proof sheet 3 may be wrapped around the position of 20c (directly above the paper tape 20b in Figure 2(A)) instead of the paper tape 20 indicated as 20c in Figure 2(A). Alternatively, another paper tape 20 may be wrapped around the position of the tape 30 designated as the moisture-proof sheet 3 in Figure 2(A), and the tape 30 designated as the moisture-proof sheet 3 may be wrapped around the paper tape 20 indicated as 20d in Figure 2(A). Alternatively, if there are no issues with contact with the mandrel m, a moisture-proof sheet 3 may be placed in place of the bottom layer of paper tape 20 (20a), and the moisture-proof sheet 3 may provide the inner surface of the paper tube core 1.

[0021] The moisture-proof sheet 3 is not provided on the paper tube core 1 in place of the paper tape 20x which is positioned as the uppermost layer in the radial direction in Figure 2(A) and provides the outer surface of the paper tube core 1, nor is it provided in place of the paper tape 20 located near the paper tape 20x that provides the outer surface. Nor does it cover (wrap) the outer surface of the paper tube 2 which is entirely made of paper tape 20. As described above, by avoiding the placement of the moisture-proof sheet 3 on the outer surface of the paper tube 2, the discharge (evaporation) of moisture from the paper tube through the outer surface of the paper tube 2 before shipment (before the material to be wound is wound) is not hindered.

[0022] (Method for detecting changes in paper tube cores due to environmental changes) Figures 3(A)(B) and 4(A)(B) show examples of measuring the pressure exerted on the paper tube core 1 by the wound material (film f) as it is wound. On the outer surface 22 of the paper tube core 1, Figures 3(A)(B) show an example in which the pressure sensor s1 of the pressure measuring device s is attached to one location in the circumferential direction of the paper tube core 1, near one of the tube ends 23, while Figures 4(A)(B) show an example in which the pressure sensors s1 are attached to four locations in the circumferential direction of the paper tube core 1, near both tube ends 23. In the example shown in Figures 4(A) and 4(B), the pressure sensors s1 are arranged so that the distance between them is 90 degrees in the circumferential direction of the paper tube core 1 at both ends 23, and a total of eight pressure sensors s1 are attached to one paper tube core 1.

[0023] In Figure 4(B), which shows the left tube end 23 of the paper tube core 1 in Figure 4(A), 41 indicates the mounting position of a reference pressure sensor s1, 42 indicates the mounting position of another pressure sensor s1 located 90 degrees clockwise from the reference mounting position 41, 43 indicates the mounting position of yet another pressure sensor s1 located another 90 degrees clockwise from position 42 (180 degrees from the reference position 41), and 44 indicates the mounting position of yet yet another pressure sensor s1 located another 90 degrees clockwise from position 43 (270 degrees from the reference position 41). The arrangement of the pressure sensors s1 located closer to the right tube end 23, as viewed from the right tube end 23, is the same as in Figure 4(B) (however, it is symmetrical to the arrangement in Figure 4(B)).

[0024] The above-mentioned reference mounting position 41 is adjacent to the adhesive portion 24 that adheres the end of the film f, which is the material to be wound, to the surface of the paper tube 2, which is the starting point of winding. On the outer surface of the paper tube 2, the adhesive portion 24 is a region formed in the shape of a line that extends along the axial direction of the paper tube 2, that is, the direction in which the paper tube 2 extends. The adhesive portion 24 may be formed by attaching double-sided tape to the paper tube 2, or it may be formed by applying a water-soluble polymer to the paper tube 2 as described in Japanese Patent Application Publication No. 2018-30713. In addition, even if the adhesive portion 24 is not provided, the reference position 41 can be set while avoiding the adhesive portion 24 and adjacent to the reference position 41, as in the example in Figures 3 and 4 above, while avoiding the region that will be the starting point of winding.

[0025] The pressure measuring device s comprises the pressure sensor s1 (Figures 3(A)(B), 4(A)(B), and 5(A)), software for processing pressure measurement data and a computer (not shown) on which the software is installed, an interface s2 for connecting the pressure sensor s1 to the computer, and a connection cord (USB) s3 (Figure 5(B)). The pressure sensor s1 is preferably a thin type suitable for measuring the above pressure when the film f is wound up. In this example, a pressure sensor s1 with a total length of 228 mm, a total width of 14 mm, and a maximum thickness of 0.2 mm was used. A pressure sensor s1 that is used for measuring the half-shutter pressure during the manufacture of commercially available cameras can be used as such. After attaching the pressure sensor s1 to the outer surface of the paper tube core 1 with cellophane tape, the film f to be wound onto the paper tube core 1 is wound, and the pressure is measured. In addition to the cellophane tape, commercially available double-sided tape can be used to fix the pressure sensor s1 to the paper tube core 1.

[0026] In parallel with the measurement of the pressure, the temperature and humidity of the environment in which the paper tube core 1 is placed are also measured. A commercially available thermometer / hygrometer t can be used to measure the temperature and humidity (Figure 3(C)). The thermometer / hygrometer t comprises a main unit t2 equipped with a display unit for displaying temperature and humidity, and a temperature / humidity sensor t1 connected to the main unit t2. In this example, the main unit t2 is connected to the computer in the same manner as the pressure sensor s1, so that the changes in pressure and temperature / humidity are displayed on the same screen (Figure 6). Note that the temperature / humidity sensor t1 only needs to be placed near the temperature / humidity sensor t1 so as to be able to measure the temperature and humidity of the environment in which the paper tube core 1 is placed, and does not need to be attached to the paper tube core 1.

[0027] In the examples in Figures 3(A) and 3(B), the (axial) length of the paper tube 2 is 40 mm longer than the width (left-right) length of the film f, and the mounting position 41 of the pressure sensor s1 on the outer surface 22 of the paper tube 2 is the same as the mounting position 41 in Figure 4, which is adjacent to the adhesive part 24 that adheres the end of the film f, which is the starting point of winding, to the surface of the paper tube 2. On the other hand, in the example in Figure 4, the (axial) length of the paper tube 2 is the same as the width (left-right) length of the film f, and the base end (sensor handle) of the pressure sensor protrudes from the tube end 23 of the paper tube 2. In both examples in Figures 3 and 4, the temperature and humidity at the slit (cut) of the paper tube in the paper tube storage room are measured, and the changes in film pressure and temperature / humidity were measured for 24 hours after slitting. It is possible to use eight pressure sensors simultaneously in the arrangement shown in Figure 4, but in addition to the arrangement in Figure 4, it is possible to perform pressure measurement by selecting from the following three patterns. Pattern 1: On one side of the paper tube in the axial direction (either left or right), measure four points at 90-degree intervals around the circumference of the paper tube as shown in Figure 4(B). Pattern 2: On both the axial (left and right) sides of the paper tube, measurements are taken at two locations on each side (four locations in total, left and right) at 180-degree intervals around the circumference of the paper tube. Pattern 3: Measure two points on one axial side of the paper tube (either left or right) at 180-degree intervals around the circumference of the paper tube. In all of the above patterns, the temperature and humidity of the storage environment for the paper tubes shall also be measured simultaneously, and the changes in pressure, temperature, and humidity shall be recorded. In the analysis method using the apparatus configured as described above, it is possible to visualize how much the film pressure affects the paper tube (initial pressure can be confirmed), to confirm whether pressure changes occur during the 24 hours after slitting (24-hour pressure measurement is possible), to extract and graph the pressure values ​​for those 24 hours to visualize them (preliminary values ​​can be reported), and to check the changes in pressure values ​​under different conditions (comparison is possible under eight different conditions). The configuration shown in Figures 3(A) and 3(B) uses one pressure sensor per paper tube, allowing for the detection of pressure differences under varying conditions of the paper tubes (e.g., paper tubes with high and low moisture content). Although not shown in the diagram, one pressure sensor can be attached to each axial (left and right) end of the paper tube to detect the presence or absence of a pressure difference between the left and right sides, or multiple pressure sensors can be attached to the same side (left and right) to increase the amount of data and improve the reliability of the pressure values.

[0028] The decrease in pressure applied to the paper tube core as measured above indicates a contraction in the diameter of the paper tube core 1, while an increase in this pressure indicates an expansion in the diameter of the paper tube core. By observing the relationship between the above pressure and the temperature and humidity of the environment in which the paper tube core is placed, appropriate management of the paper tube 2 and film f can be performed. Figure 6(A) shows an example of a graph illustrating the pressure changes and temperature / humidity changes of a conventional paper tube (paper tube core 1) without a moisture-proof sheet, as measured above. Humidity is relative humidity, and temperature is in degrees Celsius (the same applies to the examples and comparative examples described later). Figure 6(A) shows data collected on the outer surface of the paper tube core 1 by placing a pressure sensor s1 near the left tube end 23, as shown in Figures 3(A) and 3(B), and a pressure sensor s1 near the right tube end 23. The two pressure sensors s1 measured the change in the outer surface pressure of the paper tube core 1.

[0029] In Figure 6(A), the dashed line g1 is a graph showing the temperature change measured by the above temperature and humidity meter, and the dashed line g2 is a graph showing the humidity change measured by the above temperature and humidity meter. Also in Figure 6(A), the dashed line g3 is a graph showing the pressure change measured by the pressure sensor s1 located near the right end 23 of the pipe, and the solid line g4 is a graph showing the pressure change measured by the pressure sensor s1 located near the left end 23 of the pipe. Figure 6(B) shows the film f used for measurement in Figure 6(A). The film f (PET aluminum vapor-deposited film) was wound onto a paper tube 2 with an inner diameter of 76.2 mm and a thickness of 10 mm, without a moisture-proof sheet 3, and was photographed after being unwound from the paper tube 2.

[0030] The measurement results shown in Figure 6(A) indicate that the pressure on the paper tube core 1 decreased in conjunction with the decrease in temperature and humidity. Specifically, a decrease in pressure at the tube end 23 was confirmed during the period when the temperature and humidity decreased, and it is thought that the diameter of the paper tube core 1 contracted during this period, leading to the formation of wrinkles on the film f shown by the arrows in Figure 6(B). In Figure 6(B), the top is the winding direction of the film onto the paper tube core 1.

[0031] (Examples and comparative examples) Next, we will discuss specific examples, namely, examples and comparative examples. In this example, we investigated the relationship between temperature, humidity, and the wrinkles that occur in the film f with and without the moisture barrier sheet 3 for a paper tube core in an example where aluminum sandpaper with a moisture permeability of 0.2 g / m²·24 hours or less was provided as a moisture barrier sheet 3 at the positions indicated by spots in Figure 2(A), and for a paper tube core in a comparative example where the moisture barrier sheet 3 was not provided. In the tables described later, "φ76.2×12" indicates the inner diameter (76.2 mm) and thickness (12 mm) of the paper tube 2. "NC-H" indicates paper tube core 1, a comparative example without the moisture-proof sheet 3. "NC-BL" indicates paper tube core 1, an example with the moisture-proof sheet 3, as shown in Figure 2(A). Table 1 shows the evaluation levels and evaluation items, and Table 2 shows the temperature and humidity setting conditions as the evaluation method.

[0032] [Table 1]

[0033] [Table 2]

[0034] Figure 7 shows the changes in temperature, humidity, and water vapor content in the environment where the paper tube core 1 is placed, as an evaluation method. Table 3 shows the wrinkle formation (wrinkle confirmation) and its considerations for elapsed time 1 to 3 days (#1 to #3), and Table 4 shows the wrinkle formation (wrinkle confirmation) and its considerations for elapsed time 4 to 6 days (#4 to #6).

[0035] [Table 3]

[0036] [Table 4]

[0037] Table 5 summarizes the state of the film f being wound up.

[0038] [Table 5]

[0039] For each film roll in the comparative examples and examples, the temperature and humidity were sequentially changed as shown in Table 2, and the maximum height of the wrinkles that occurred in the final environment of 10 degrees Celsius and 10 percent relative humidity is shown in Figure 9. Figure 10 shows the unfolded state of the film after being unwound from each paper tube. Looking at Figure 10, it can be seen that wrinkles occurred along the entire width in the axial direction of the film f when it was unfolded in the axial direction of the paper tube in the comparative examples, φ76.2×12NC-H moisture content 10 percent (upper left) and φ76.2×12NC-H moisture content 9 percent (upper center).

[0040] In particular, with respect to the φ76.2×12NC-H film f with 9 percent moisture content (Figure 10, upper center), Figure 19(B), which shows an actual image of the wrinkles in Figure 19(A), clearly shows the wrinkles v that extend across the entire width. Figures 19(C) and (D) show the image of the wrinkles v that appear only near the ends in the width direction (the axis w of the paper tube) and their actual images.

[0041] In the examples shown in Table 5, the middle section of Figure 10, and the lower section of Figure 10, no wrinkles were observed across the entire width of the film, confirming the effectiveness of the moisture-proof sheet. Figure 11 shows the actual wrinkle conditions at the ends of the film wound onto each paper tube. Furthermore, the location of wrinkles in the film relative to the winding direction was investigated using the formula shown in Equation 1 below. Specific values ​​obtained by substituting the film thickness into Equation 1 are shown in Table 6.

[0042]

number

[0043] In the formula shown in equation 1 above, L is the total length (m) of the film f (winding film) to be wound, D is the outer diameter (m) of the film f (film roll) wound onto the paper tube 2, d is the outer diameter (m) of the paper tube core 1, t is the thickness of the film f, and π is the ratio of a circle's circumference to its diameter (pi). Calculation examples are shown in Table 6.

[0044] [Table 6]

[0045] Table 7 shows the changes in the condition of the paper tube before and after evaluation. In Table 7, the center of the paper tube refers to the position of arrow u2, which is the central arrow among the three arrows shown in Figure 8(A). In Table 7, "the same position as before the test" refers to the position of arrow u2, which is located in the axial center as shown in Figure 8(A). The values ​​measured at the positions of arrows u1 and u3 on the left and right of Figure 8(A) are shown in Tables 8 and 9.

[0046] [Table 7]

[0047] Table 8 shows the changes before and after evaluation of the paper tube without the moisture-proof sheet 3 at each position in the paper tube axis direction indicated by the arrows in Figure 8(A), and Table 9 shows the changes before and after evaluation of the paper tube with the moisture-proof sheet 3 at each position in the paper tube axis direction indicated by the arrows in Figure 8(A). A summary of the evaluation results is provided in Table 10. In Tables 8 and 9, "No. side" refers to the position of arrow u1 in Figure 8(A), and "No. opposite side" refers to the position of arrow u3 in Figure 8(A).

[0048] [Table 8]

[0049] [Table 9]

[0050] [Table 10]

[0051] Figure 12 shows the changes in the paper tube without the moisture barrier sheet 3 at the inner diameter r1 on the No. side (position of arrow u1 in Figure 8(A)), the inner diameter r2 in the center, and the inner diameter r3 on the opposite side of the No. (position of arrow u3 in Figure 8(A)), as shown in Figure 8(B). Figures 13 and 14 show the changes in the paper tube with the moisture barrier sheet 3. From Figure 12, it can be seen that in the comparative example paper tube, the outer diameter and moisture content of the paper tube decrease uniformly at both ends and in the center (r1≒r2≒r3). Therefore, it is considered that wrinkles occurred in the film over the entire width in the comparative example.

[0052] Figure 13 shows that the outer and inner diameters r10 and r30 and moisture content change at both ends of the paper tube, while the outer and inner diameters r20 and moisture content change are small in the center of the paper tube. Therefore, in the examples with 10% and 9% moisture content, it is thought that wrinkles occurred in the film only near both ends of the paper tube. Furthermore, Figure 14 shows that, as with the paper tubes with 8%, 7%, and 6% moisture content, the initial moisture content is low, resulting in small changes in moisture content and suppressed shrinkage of the outer and inner diameters. Therefore, it is desirable to keep the moisture content of the paper tube at 8% or less, and particularly preferable to keep it at 7% or less.

[0053] Next, let's summarize the above considerations from the perspective of water movement. The movement of moisture (discharge from the paper tube) in a paper tube without the moisture barrier sheet 3 is shown by arrows in Figure 8(D), and the movement of moisture (discharge from the paper tube) in a paper tube equipped with the moisture barrier sheet 3 is shown by arrows in Figure 8(E). As can be seen from the moisture movement shown in Figure 8(D), in each comparative example (φ76.2×12NC-H) with paper tube moisture content of 10%, 9%, and 8%, the moisture content of the paper tube decreased rapidly under the conditions of 40 degrees Celsius and 10 percent relative humidity, and 30 degrees Celsius and 10 percent relative humidity. It can be inferred that, along with this decrease, the outer and inner diameters r1, r2, and r3 of the paper tube also contracted significantly. In other words, in the paper tubes of the above comparative examples that do not have the moisture-proof sheet 3, as shown in Figure 8(D), moisture was released from the inner surface of the paper tube, causing the outer diameter (and inner diameter) to contract to the axial center of the paper tube, and as mentioned above, it is thought that wrinkles occurred across the entire width of the film (r1≒r2≒r3).

[0054] As can be seen from the moisture movement shown in Figure 8(E), in the examples (φ76.2×10NC-BL) with paper tube moisture content of 10%, 9%, 8%, 7%, and 6% under the conditions of 40°C / 10% relative humidity and 30°C / 10% relative humidity, the moisture content of the paper tube decreased under the conditions of 40°C / 10% relative humidity and 30°C / 10% relative humidity, and it is thought that the outer diameter (and inner diameters r10, r30) of the paper tube also contracted with this decrease. However, by providing a moisture-proof sheet on the inner circumferential surface of the paper tube, the release of moisture from the inner circumferential surface of the paper tube was suppressed, and the change in the outer diameter (and inner diameter) of the central part in the axial direction of the paper tube was suppressed, and as a result, it is presumed that no wrinkles occurred in the central part of the paper tube (r10 <r20>r30).

[0055] Figure 15 shows graphs illustrating the pressure changes over time for NC-H (solid line) and NC-BL (dotted line) tubes of the same size with a moisture content of 6 percent (φ76.2×12), NC-WBL (double-dotted line) tubes with a moisture content of 10 percent, and NC-H (triple-dotted line), NC-BL (quadruple-dotted line), and NC-WBL (dashed line) tubes of the same size with a moisture content of 10 percent (φ76.2×10). The "NC-WBL" mentioned above is a configuration in which the tape 30 in Figure 2(A) and the 20x in the same figure are replaced with a moisture-proof sheet 3 (aluminum sandpaper with a moisture permeability of 0.2 g / m²·24 hours or less). In other words, "NC-WBL" is a configuration in which the moisture-proof sheet 3 is placed both near the inner circumference and on the outer circumference of the paper tube.

[0056] Figure 16 shows the graphs (solid line) for NC-H with a paper tube moisture content of 6 percent and a φ76.2 × 12 tube, and the graph (dotted line) for NC-H with a paper tube moisture content of 10 percent and a φ76.2 × 10 tube, extracted from Figure 15. The evaluation is as shown in Figure 16. Furthermore, Figure 17 extracts the graphs (single dashed line) for NC-BL with a paper tube moisture content of 6 percent and a diameter of φ76.2 × 12 and a diameter of NC-BL with a paper tube moisture content of 10 percent (quadred dashed line) from Figure 15, and their evaluations are as shown in Figure 17. Figure 18 shows graphs extracted from Figure 15, all assuming a paper tube moisture content of 10 percent: a dashed-dotted line for φ76.2×12 NC-WBL, a dashed-dotted line for φ76.2×10 NC-WBL, and a dashed line for φ76.2×10 NC-WBL.

[0057] Looking at the graphs of NC-WBL for φ76.2×12 (10% moisture content), shown by the dashed and dotted lines in Figure 18, and the graph of NC-WBL for φ76.2×10 (10% moisture content), shown by the dashed line (after 70 hours), it can be seen that even when the moisture barrier sheet 3 (aluminum sandpaper) is placed on both the inner and outer surfaces of the paper tube, there is not much difference compared to the example where the moisture barrier sheet 3 is placed only on the inner surface 21 of the paper tube 2 (Figures 1(B) and 2(A)). This shows that placing the moisture barrier sheet 3 on both the inside and outside of the paper tube does not provide a greater effect than a paper tube with the moisture barrier sheet placed only on the inner surface.

[0058] Regarding the NC-WBL mentioned above, it can be inferred from the pressure waveform that moisture does not easily escape from the paper tube, but the problem is the low initial pressure. In this regard, it is thought that the pressure value is low because the paper tube has a high moisture content and its strength has decreased. In other words, the above problem is that the strength of the paper tube decreases due to moisture (the paper tube becomes softer due to moisture), so there is a concern that the material being wound (film, etc.) will expand and contract in response to environmental changes, and the paper tube will not be able to withstand the internal stress and will deform. As a countermeasure, it is conceivable to provide paper tubes with low moisture content, i.e., dried paper tubes, from which moisture has been sufficiently removed before shipment, but in paper tubes (NC-WBL) that have moisture-proof sheets 3 on both the inner and outer surfaces of the paper tube, it is difficult to remove moisture and dry the paper tube, and it is understood that this will increase the cost due to the increased drying time.

[0059] Regarding the comparative examples and examples described above, the specifications of the paper core 1 that are most preferable for reducing wrinkles are summarized below. 1) Thickness of the paper tube (paper tube core 1) Both 10mm and 12mm thicknesses are acceptable. The pressure values ​​also indicate that the 10mm thickness is strong enough, and it offers good cost performance. Furthermore, the specifications described herein refer to the paper tube core 1 used as a comparative example and example, and do not preclude the use of paper tube thicknesses other than 10 mm or 12 mm within the scope of achieving the effects of the present invention. 2) Setting up the barrier layer The inclusion of a barrier layer, i.e., a moisture-proof sheet 3, is essential. Based on the above results, the moisture-proof sheet 3 can be placed in the innermost layer of the paper tube, that is, simply by placing it at the position indicated by 30 (indicated by the dots) in Figure 2(A), to obtain sufficient wrinkle suppression.

[0060] 3) Setting of paper tube moisture content (factory setting) The moisture content of the paper tubes at the time of factory shipment shall not exceed 8 percent. It is particularly preferable to set the moisture content of the paper tubes at the time of factory shipment to 7 percent or less. In other words, since the maximum length of wrinkles from the end face of the paper tube is approximately the same at 8 percent to 6 percent moisture content (50 to 45 mm), the preferred moisture content of the paper tubes is set to 7 percent or less as described above.

[0061] 4) Adhesive Regarding the adhesive applied to secure the film (winding) end to the paper tube before winding, there is some concern that using a hand-applied water-soluble adhesive might introduce moisture into the paper tube. However, based on previous findings, no results have shown that hand-applied water-soluble adhesives significantly affect wrinkle formation, and therefore, the use of hand-applied water-soluble adhesives is considered acceptable. This hand-applied water-soluble adhesive consists of vinyl acetate, polyvinyl alcohol, and acrylic resin dissolved in an aqueous solution.

[0062] However, it is generally undesirable to apply moisture to the surface of the paper tube core 1, which has been dried at the time of shipment, and there are concerns that wrinkles may occur due to warping of the paper tube caused by differences in moisture content at different points on the surface of the paper tube. Furthermore, with hand-applied water-soluble adhesives, since they are applied by hand, there are inconsistencies in the thickness of the applied adhesive, and there are concerns that the winding of the film may be affected by these inconsistencies, causing wrinkles. Taking the above concerns into account, it is preferable to use double-sided tape with a stable thickness. In addition, since double-sided tape has a base material, it may have an effect on the film such as leaving steps, and considering this effect, it is even more preferable to use double-sided tape without a base material.

[0063] To prevent the shrinkage described above from occurring in dry environments, the paper tubes were shipped after being dried to the maximum extent. However, after the material to be wound was placed on them, the paper tubes absorbed moisture, resulting in a step (deformation of the paper tube) on the outer surface of the paper tube due to the pressure difference between the axially wound portion of the paper tube and the unwound portions at both ends of the paper tube. In this invention, by supplying the moisture-proof material (moisture-proof sheet 3) to the entire axial area of ​​the paper tube in a shallow layer on the inner circumferential surface side of the paper tube, the discharge of moisture from the inner circumferential surface side of the paper tube can be prevented. On the other hand, the discharge of moisture from the outer circumferential surface side of the paper tube is blocked by the material being wound. This suppresses deformation of the paper tube and prevents wrinkle formation in the material being wound. When drying paper tubes for shipment, if moisture-proof material (moisture-proof sheet 3) is placed on both the inner and outer sides of the paper tube as described above, it becomes difficult for moisture to drain, and the drying process takes longer. However, by placing the moisture-proof material (moisture-proof sheet 3) only on the inner side of the paper tube, the above problem before shipment can be avoided.

[0064] (Example of change) In the above embodiment, aluminum sandpaper was used for the moisture barrier sheet 3. However, other materials such as the aforementioned transparent vapor-deposited barrier film, barrier film, aluminum vapor-deposited film, polysand kraft paper, and the aforementioned paper-based moisture barrier material can also be used as the moisture barrier sheet 3. As mentioned above, any sheet other than those described above may be used as the moisture barrier sheet 3, as long as it has a moisture permeability of 25 g / m²·24 hours or less when placed in an environment of 40 degrees Celsius and 90 percent relative humidity for 24 hours. Furthermore, while aluminum foil offers the best moisture-proof performance, using aluminum foil results in paper tubes becoming industrial waste that cannot be recycled. Therefore, from an environmental perspective, it is preferable to use moisture-proof sheets 3 made of materials other than aluminum foil.

[0065] Table 11 shows the relationship and characteristics of moisture permeability and paper tube moisture of moisture barrier sheet 3. As the moisture barrier sheet 3, polysand kraft paper with a moisture permeability of 25 g / m²·24 hours or less under conditions of 40 degrees Celsius and 90 percent relative humidity shall be used. In particular, it is possible to use polysand kraft paper with a moisture permeability of 5.0 g / m²·24 hours or more, but it is preferable to use polysand kraft paper with a moisture permeability of 5.0 g / m²·24 hours or less, and it is even more preferable to use polysand kraft paper with a moisture permeability of 2.0 g / m²·24 hours or less, as can be seen from the characteristics column of Table 11.

[0066] [Table 11]

[0067] Regarding moisture content in the paper tube, it is necessary to manage it based on the moisture permeability value. In this regard, Table 12 shows the relationship between moisture content in the paper tube and wrinkles that occurred in the wound film for the materials considered for use as moisture barrier sheet 3. Table 12 also shows the results of testing each moisture barrier material (moisture barrier sheet 3) under conditions of 40 degrees Celsius and 90 percent relative humidity. In Table 12, × indicates that when the film f wound onto the paper tube core 1 was unwound and spread out, wrinkles occurred along the entire width in the direction of the film roll (paper tube) axis (film width direction), △ indicates that wrinkles occurred only within a range of 10 cm or less from both ends in the width direction of the film, ○ indicates that wrinkles occurred only within a range of 5 cm or less from both ends in the width direction of the film, and ◎ indicates that no wrinkles occurred.

[0068] [Table 12]

[0069] As shown in Table 12, when the paper core moisture content was set to 10 percent, the aluminum sandpaper, barrier film, transparent vapor-deposited barrier film, and aluminum vapor-deposited film, each with the moisture permeability listed in the table, showed wrinkles in the range of 10 cm or less from both ends in the width direction (Figure 19(C)), but no wrinkles were observed in the range of more than 10 cm from both ends in the width direction of the film (rolled material). On the other hand, when the paper core moisture content was set to 10 percent, the polysand kraft paper and the paper-based moisture-proof material used as a comparison as a moisture-proof sheet, as well as those without a moisture-proof sheet, all showed wrinkles across the entire width (entire area) of the unfolded rolled material (Figure 19(A)(B)).

[0070] As shown in Table 12, when the paper core moisture content was 9 percent, wrinkles were observed in the aluminum sandpaper, barrier film, and transparent vapor-deposited barrier film within a range of 5 cm or less from both ends in the width direction (Figure 19(C)), but no wrinkles were observed in the range exceeding 5 cm from both ends in the width direction. When the paper core moisture content was 9 percent, wrinkles were observed in the aluminum vapor-deposited film within a range of 10 cm or less from both ends in the width direction (Figure 19(C)), but no wrinkles were observed in the range exceeding 10 cm from both ends in the width direction. On the other hand, when the moisture content of the paper core was set to 9 percent, wrinkles were observed across the entire width (entire area) of the unfolded rolled material in all cases, including those using the polysand kraft paper and the comparative paper moisture-proof material as moisture-proof sheets, as well as those without a moisture-proof sheet, all of which had the moisture permeability described in Table 13 (Figure 19(A)(B)).

[0071] As shown in Table 12, when the paper core moisture content was 8 percent, no wrinkles were observed in the aluminum sandpaper, barrier film, or transparent vapor-deposited barrier film across the entire area of ​​the unfolded roll. When the paper core moisture content was 8 percent, the aluminum vapor-deposited film with the moisture permeability described in Table 12 showed wrinkles in the area up to 5 cm from both ends in the width direction (Figure 19(C)), but no wrinkles were observed in the area beyond 5 cm from both ends in the width direction. When the paper core moisture content was 8 percent, the polysand kraft paper with the moisture permeability described in Table 13 showed wrinkles in the area up to 10 cm from both ends in the width direction (Figure 19(C)), but no wrinkles were observed in the area beyond 10 cm from both ends in the width direction of the film (rolled material). When the paper core moisture content was set to 8 percent, wrinkles were observed across the entire width (entire area) of the unfolded rolled material in both cases: when using the comparative paper moisture-proof material with the moisture permeability described in Table 12 as a moisture-proof sheet, and when not using a moisture-proof sheet (Figure 19(A)(B)).

[0072] As shown in Table 12, when the paper core moisture content was set to 7 percent, no wrinkles were observed in the entire area of ​​the unfolded rolled material for the aluminum sandpaper, barrier film, transparent vapor-deposited barrier film, and aluminum vapor-deposited film, each with the moisture permeability listed in the table. When the paper core moisture content was set to 7 percent, the polysand kraft paper with the moisture permeability listed in Table 12 showed wrinkles in the area up to 5 cm from both ends in the width direction (Figure 19(C)), but no wrinkles were observed in the area beyond 5 cm from both ends in the width direction of the film (rolled material). When the paper core moisture content was set to 7 percent, wrinkles were observed across the entire width (entire area) of the unfolded rolled material in both cases: when using the comparative paper moisture-proof material with the moisture permeability described in Table 12 as a moisture-proof sheet, and when not using a moisture-proof sheet (Figure 19(A)(B)).

[0073] As shown in Table 12, when the paper core moisture content was set to 6 percent, no wrinkles were observed in the entire area of ​​the unfolded rolled material for the aluminum sandpaper, barrier film, transparent vapor-deposited barrier film, aluminum vapor-deposited film, and polysand kraft paper, each of which has the moisture permeability listed in Table 12. When the paper core moisture content was set to 6 percent, wrinkles were observed in the range of 10 cm or less from both ends in the width direction (Figure 19(C)) for the comparative paper moisture-proof materials with the moisture permeability listed in Table 12, either using a moisture-proof sheet or not using a moisture-proof sheet, but no wrinkles were observed in the range of 10 cm or less from both ends in the width direction.

[0074] From the results shown in Table 12, it can be seen that for aluminum sandpaper with a moisture permeability of 0.2 / m²·24 hours or less, barrier films with a moisture permeability of 0.2 / m²·24 hours to 1.0 / m²·24 hours, and transparent vapor-deposited barrier films with a moisture permeability of 0.5 / m²·24 hours to 2.0 / m²·24 hours, it is preferable to have a paper core moisture content of 8 percent or less. For aluminum vapor-deposited films with a moisture permeability of 2.0 / m²·24 hours to 5.0 / m²·24 hours, it is preferable to have a paper core moisture content of 7 percent or less. For polysand kraft paper with a moisture permeability of 15 / m²·24 hours to 25 / m²·24 hours, it is preferable to have a paper core moisture content of 6 percent or less. Table 12 provides examples of polysandcraft paper with a moisture permeability in the range of 15 g / m²·24 hours to 25 g / m²·24 hours, but this does not exclude polysandcraft paper with a moisture permeability of less than 15 g / m²·24 hours.

[0075] Table 13 shows the relationship between wrinkles in a film wound onto a paper tube core 1 without a moisture-proof sheet 3 (internal moisture-proofing material) and the moisture content of the paper tube, while Table 14 shows the relationship between wrinkles in a film wound onto a paper tube core 1 with a barrier film as a moisture-proof sheet 3 and the moisture content of the paper tube. In Tables 13 and 14, the number of wrinkles (m) refers to the remaining number of m when even slight wrinkle formation is observed, i.e., the length of film remaining on the paper tube (see Equation 1), and the maximum width of the wrinkles is the maximum width of the wrinkles in the film width direction (paper tube axis direction). Dry conditions of 10 degrees Celsius and 30 percent relative humidity were set to simulate winter conditions in Japan, and 40 degrees Celsius and 10 percent relative humidity were set to simulate a desert climate that does not actually exist in Japan, in order to intentionally induce wrinkles.

[0076] [Table 13]

[0077] [Table 14]

[0078] Tables 13 and 14 show that, under a setting of 40 degrees Celsius and 10 percent relative humidity, in the range of 8 percent to 10 percent moisture content of the paper tube, the paper tube core equipped with a moisture-proof sheet (internal moisture-proofing material) shows a value an order of magnitude smaller in the maximum wrinkle width compared to the paper tube core 1 without the moisture-proof sheet 3, and the amount of wrinkles is more than 40 m shorter. Specifically, under a setting of 40 degrees Celsius and 10 percent relative humidity, at a paper tube moisture content of 8 percent, the paper tube core 1 equipped with the moisture-proof sheet 3 shows a wrinkle length of 230 m and a maximum wrinkle width of 5.0 cm, while the paper tube core 1 without the moisture-proof sheet 3 shows a wrinkle length of 270 m and a maximum wrinkle width of 33 cm.

[0079] As described above, the difference between the paper tube core 1 equipped with the moisture-proof sheet 3 and the paper tube core 1 without the moisture-proof sheet 3 becomes more pronounced as the moisture content of the paper tube increases. Specifically, at a setting of 40 degrees Celsius and 10 percent relative humidity, with a paper tube moisture content of 9 percent, the paper tube core 1 equipped with the moisture-proof sheet 3 produced 381 m of material with a maximum width of 7.5 cm, while the paper tube core 1 without the moisture-proof sheet 3 produced 491 m of material with a maximum width of 70 cm. With a paper tube moisture content of 10 percent, the paper tube core 1 equipped with the moisture-proof sheet 3 produced 343 m of material with a maximum width of 12.0 cm, while the paper tube core 1 without the moisture-proof sheet 3 produced 450 m of material with a maximum width of 70 cm.

[0080] Furthermore, from Tables 13 and 14, it can be seen that, at a setting of 10 degrees Celsius and 30 percent relative humidity, in the range of 8 percent to 10 percent moisture content of the paper tube, the paper tube core 1 equipped with the moisture barrier sheet 3 (internal moisture barrier material) shows a maximum wrinkle width that is more than an order of magnitude smaller than that of the paper tube core 1 without the moisture barrier sheet 3, and the amount of wrinkles that occur is more than 190 m shorter. Specifically, at a setting of 10 degrees Celsius and 30 percent relative humidity, with a paper tube moisture content of 8 percent, the paper tube core 1 equipped with the moisture barrier sheet 3 shows a wrinkle length of 0 m and a maximum wrinkle width of 0 cm, while the paper tube core 1 without the moisture barrier sheet 3 shows a wrinkle length of 190 m and a maximum wrinkle width of 28 cm.

[0081] As described above, even at a setting of 10 degrees Celsius and 30 percent relative humidity, the above difference between the paper tube core 1 equipped with the moisture-proof sheet 3 and the paper tube core 1 without the moisture-proof sheet 3 becomes more pronounced as the moisture content of the paper tube increases. Specifically, at a setting of 10 degrees Celsius and 30 percent relative humidity, with a paper tube moisture content of 9 percent, the paper tube core 1 equipped with the moisture-proof sheet 3 produced 30 m of material with a maximum width of 2.5 cm, while the paper tube core 1 without the moisture-proof sheet 3 produced 400 m of material with a maximum width of 70 cm. With a paper tube moisture content of 10 percent, the paper tube core 1 equipped with the moisture-proof sheet 3 produced 70 m of material with a maximum width of 5.0 cm, while the paper tube core 1 without the moisture-proof sheet 3 produced 380 m of material with a maximum width of 70 cm.

[0082] Based on the results in Tables 13 and 14 described above, it can be said that, under both environmental conditions of 40 degrees Celsius and 10 percent relative humidity, and 10 degrees Celsius and 30 percent relative humidity, the paper tube core 1 equipped with the moisture-proof sheet 3 (barrier film) reliably suppresses the occurrence of wrinkles compared to the paper tube core 1 without the moisture-proof sheet 3. [Explanation of symbols]

[0083] 1. Paper tube core 2 Paper tube 3. Moisture-proof sheet 20 paper tapes 21 (Inner surface of paper tube 2) 22 Outer surface (of paper tube 2) b belt m mandrel p pulley

Claims

1. A paper tube core for winding a sheet-like material onto its outer surface, It consists of a paper tube and a moisture-proof sheet. A paper tube core is provided with the moisture-proof sheet on the inner circumferential surface side of the paper tube, thereby suppressing the evaporation of moisture from the paper tube from the inner circumferential surface to the outside of the paper tube and the absorption of moisture from the outside of the paper tube through the inner circumferential surface of the paper tube.

2. The inner circumferential surface side of the paper tube is defined as a position that does not exceed 30% of the thickness of the paper tube, extending from the inner circumferential surface of the paper tube toward the outer circumferential surface of the paper tube. The moisture-proof sheet is not provided on the outer surface side of the paper tube, that is, in the area from the outer surface of the paper tube toward the inner surface of the paper tube, not exceeding 70% of the thickness of the paper tube. The paper core winding material according to claim 1, wherein the moisture barrier sheet has a moisture permeability of 25 g / m² / 24 hours or less when placed in an environment of 40 degrees Celsius and 90 percent relative humidity for 24 hours.

3. The aforementioned paper tube is formed by stacking multiple strip-shaped paper tapes in a spiral pattern, with the outer surface of the paper tube being the upper layer of the stacked paper tapes, and the inner circumferential surface of the paper tube being the lower layer of the stacked paper tapes. The moisture-proof sheet is a sheet with moisture-proof properties, such as aluminum sandpaper, formed in a strip shape. The moisture-proof sheet is either placed on the bottom layer of the multiple paper tapes in place of the bottommost paper tape, placed directly above the bottommost paper tape, or placed on the upper layer with one or two paper tapes in between it and the bottommost paper tape. The paper core winding core according to claim 2, wherein the moisture content of the paper core, i.e., the water content of the paper core, does not exceed 8 percent.

4. A method for observing changes in a paper tube core in response to environmental changes, as described in claim 1, comprising attaching a pressure sensor to the outer surface of the paper tube core, observing the change in pressure applied to the outer surface of the paper tube core in response to changes in the temperature and humidity of the environment in which the paper tube core is placed, and investigating the effect on the paper tube core, namely changes in the diameter of the paper tube core.

5. A method for observing changes in a paper tube core according to claim 1 in response to environmental changes, comprising attaching a pressure sensor to the outer surface of the paper tube core and investigating the effect on the paper tube core due to the expansion and contraction of the object being wound in response to changes in the temperature and humidity of the environment in which the object being wound is placed.

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