High-grip paper tube and method for manufacturing the same

Abstract

To provide a cardboard core with high gripping properties without tackiness.SOLUTION: A gripping area 2 of a cardboard core 1 of the present invention is a coating layer of acrylic-styrene resin which is provided in a range in which the central angle of the cardboard core 1 is 150 degrees or less in the circumferential direction of the cardboard core 1. The length of the gripping area 2 in the circumferential direction of the cardboard core 1 is 20 mm, and a sheet material 3 is made of OPP with a width of 90 mm, a thickness of 50 μm, and a length of 200 mm in the winding direction for the cardboard core that has a diameter of 100 mm and a width of 90 mm in the axial direction. When pulled at a pulling speed of 20 mm per minute in an environment of 23 degrees Celsius and 50% RH toward the radially outward direction of the cardboard core 1, the force required to peel the sheet material 3 is 20 N or less. When the sheet material 3 is wound around the cardboard core 1 by 140 mm and pulled at the pulling speed in an environment of the above temperature and relative humidity, the friction resistance of the gripping area 2 against sliding of the sheet material in the circumferential direction of the cardboard core 1, i.e., the winding direction of the sheet material, is 120 N or more.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a high-grip paper tube and a method for manufacturing the same.

Background Art

[0002] Regarding a paper tube that is a winding core for a sheet material such as a plastic film, in order to surely fix the end portion of the sheet material where the winding of the sheet material starts and to impart a gripping property that does not allow the sheet material to rotate idly with respect to the paper tube when winding the sheet material, conventionally, a pressure-sensitive adhesive layer extending parallel to the central axis of the paper tube is disposed on the paper tube surface, and it has been proposed to fix the above-mentioned end portion of the sheet material to the paper tube surface with the pressure-sensitive adhesive layer (Patent Documents 1 and 2).

[0003] Furthermore, due to the ease of acquisition, a commercially available double-sided tape is frequently used as a specific fixing means for the above-mentioned end portion when winding the sheet material around the paper tube. The double-sided tape has adhesive layers on both the front and back surfaces. The double-sided tape was pasted on the paper tube surface along the axial direction of the paper tube, and the above-mentioned end portion of the sheet material was fixed to the paper tube surface via the double-sided tape. The conventional problems of using the above double-sided tape will be described.

[0004] The first problem is that the supplier of the sheet material who purchased the paper tube was forced to manually paste the above double-sided tape one by one on each paper tube. Also, since the above adhesive layer has tack (stickiness), it is covered with a release paper (separator) so that it does not accidentally stick to other objects or foreign substances such as dust adhere. When pasting the double-sided tape on the paper tube, the operator is also forced to remove the release paper covering the double-sided tape from the double-sided tape. Regarding the above problem of tackiness, sufficient countermeasures have not been taken even in the paper tubes provided with the above pressure-sensitive adhesive layers of Patent Documents 1 and 2, and there is no disclosure of specific solutions for tackiness in Patent Documents 1 and 2.

[0005] The second problem is that when manually attaching the double-sided tape to the paper tube as described above, it is not easy to attach the double-sided tape straight and accurately along the direction of the central axis of the paper tube. Whether it is an inexperienced operator or a skilled operator, it is often the case that the double-sided tape cannot be attached accurately and needs to be reattached. Such reattachment not only requires preparing a new double-sided tape but also forces the preparation of a new paper tube itself, and the cost is approximately twice that when reattachment is not required.

[0006] The reason for the above cost increase is that when peeling the double-sided tape from the paper tube to reattach it, the surface of the paper tube is damaged, making the paper tube defective. Even if the defective paper tube is reused and the double-sided tape is attached straight, the rough surface of the paper tube causes subtle undulations on the double-sided tape attached to it. When the sheet material end is fixed to the paper tube surface through the double-sided tape, wrinkles and slack occur, and it cannot be attached neatly. Therefore, the paper tube from which the double-sided tape has been peeled off once is discarded.

[0007] The third problem is that when it becomes necessary to reattach (re-fix) the above sheet material to the above double-sided tape and the sheet material is peeled off from the double-sided tape, a part of the double-sided tape is torn and adheres to the sheet side, which may cause foreign matter contamination depending on the use when trying to use the sheet material. That is, when a person who purchases a sheet material wound around a paper tube uses the sheet material for, for example, packaging, there is a risk of contamination of the packaged item due to the sheet material with the double-sided tape attached.

[0008] The fourth problem is that due to the thickness of the double-sided tape attached to the paper tube surface, steps occur over several turns on the wound sheet material, causing wrinkles in the sheet material. Therefore, the section with such steps of the sheet material is discarded, resulting in a loss of several meters depending on the thickness of the wound sheet material.

[0009] Proposals have also been made to eliminate the above-mentioned tackiness problem of the conventional method and make the release paper unnecessary (Patent Documents 3 to 5). In particular, those disclosed in Patent Documents 4 and 5 disclose specific means (adhesives) that do not generate tackiness until water is applied, that is, they are not sticky except when the sheet material is wound up, and are considered extremely useful means for eliminating double-sided tape.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0011] However, the inventor of the present invention was not satisfied with the usefulness of the inventions disclosed in the above-mentioned Patent Documents 4 and 5, and after intensive research, created the present invention. The present invention has a grip property that does not cause idling when the sheet material is wound up, and avoids tackiness regardless of the application of water by eliminating the adhesive.

Means for Solving the Problems

[0012] In the present invention, there is provided a paper tube having a grip region on its outer peripheral surface for gripping an end portion of a sheet material to be wound and preventing the sheet material from idling. The sheet material is any one of a plastic film, a metal foil, a cloth, and a non-woven fabric. The grip region is at least one strip-shaped region extending along the axial direction of the paper tube or is composed of a plurality of regions intermittently provided along the axial direction. The grip region is a resin layer provided in a range where the central angle of the paper tube in the circumferential direction of the paper tube is 150 degrees or less. The resin of the resin layer is at least one solid resin of an acrylic resin, an acrylic-styrene resin, a polyurethane resin, an alkyd resin, and a silicone resin. For a paper tube set to a diameter of 100 mm and an axial width of 90 mm, the sheet material is biaxially stretched polypropylene with a width of 90 mm, a thickness of 50 μm, and a length in the winding direction of 200 mm. In the axial direction of the paper tube, the grip region has the same length as the length of the paper tube 1. In the circumferential direction of the paper tube, the length of the grip region is 20 mm. The leading end side, which is the start end side of the winding of the sheet material, is attached to the entire grip region. When pulled from the grip region in the radially outward direction of the paper tube at a tensile speed of 20 mm per minute in an environment of 23 degrees Celsius and 50% RH, the force required for peeling the sheet material in the radially outward direction of the paper tube is 20 N or less. The sheet material is wound around the paper tube by 140 mm. When the position of the rear end side of the sheet material that is not wound around the paper tube is pulled in the radially outward direction of the paper tube at the above tensile speed in the above environment, a high-grip paper tube is provided in which the frictional resistance against the sliding of the sheet material on the surface of the paper tube is 120 N or more. Furthermore, the present invention can provide a high-grip paper tube in which the resin layer constituting the grip region is a coating layer of the acrylic-styrene resin or the acrylic resin having a minimum film-forming temperature of 0 degrees Celsius or more and 2 degrees Celsius or less and a glass transition temperature of -10 degrees Celsius or more and 0 degrees Celsius or less. Furthermore, in the present invention, the resin of the resin layer is an acrylic-styrene copolymer or an acrylic ester. In the grip region, the amount of the resin is 11.5 g or more per square meter, and the thickness of the resin layer in the grip region is 20 μm or less. Thus, the high-grip paper tube according to claim 2 can be provided. Still further, in the present invention, a resin liquid is sprayed onto the surface of the paper tube, and after spraying, the resin liquid on the surface of the paper tube is dried, so that the grip region is formed as a coating layer made of the solid content of the resin. Thus, a method for manufacturing the high-grip paper tube can be provided, wherein the resin liquid contains the resin constituting the resin layer. Furthermore still, in the present invention, the resin liquid is a dilution of an emulsion of the water-soluble resin with water, and the grip region is formed as a coating layer made of the solid content of the resin by natural drying. Thus, a method for manufacturing the high-grip paper tube can be provided. Also, in the present invention, prior to the spraying of the resin liquid, plasma irradiation is applied to at least the region of the surface of the paper tube that forms the grip region. Thus, a method for manufacturing the high-grip paper tube according to claim 4 can be provided.

Advantages of the Invention

[0013] The present invention can ensure the grip property required when winding a sheet material around a paper tube while eliminating tackiness. By forming the grip region, the present invention can impart to the paper tube a grip property that allows the sheet material to be wound without idling. In particular, in the present invention, it is not necessary to apply water to exhibit the grip property. By implementing the present invention, it is not necessary to use a double-sided tape on the paper tube, and the above-described first to fourth problems caused by using the double-sided tape can be solved. Specifically, by implementing the present invention, the labor of pasting the double-sided tape can be saved. For example, when the paper tube has a length of 2 m, it was extremely difficult to paste the double-sided tape straight, but this problem has been eliminated. By implementing the present invention, when the sheet material is rewound, the sheet material is cleanly peeled off from the grip region, and the sheet material can be used until the end. Moreover, by implementing the present invention, the peelability is excellent, enabling the reuse of the paper tube without damaging it. When using the sheet material wound around the paper tube or recycling the used sheet material, the mixing of foreign substances can be reduced. That is, by implementing the present invention, the fear of contaminating the objects in contact with the sheet material can be reduced. By implementing the present invention, the labor involved in pasting the double-sided tape is avoided, and the problem of pasting failure on the paper tube, which often occurs with the double-sided tape, is solved. And by implementing the present invention, the above-mentioned step marks, which were prominent in the use of the double-sided tape, can be reduced, and for the wound sheet material, the section that was discarded as excess, i.e., the lower winding, during use can be reduced. In particular, by adopting an acrylic-styrene resin that is water-soluble in the grip area, the use of solvents is eliminated, making it environmentally friendly. According to the present invention described in claims 4 to 6, specific means for manufacturing the high-grip paper tube according to the above-mentioned present invention can be provided.

Brief Explanation of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0015] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. (Overview) In the high-grip paper tube according to the present invention, an acrylic-styrene resin film is coated on the surface (outer peripheral surface) of the paper tube 1 in parallel with the central axis of the paper tube 1 to form a grip region 2. The resin film is formed by spraying fine particles of the resin dissolved in water onto the paper tube surface (Figs. 1 and 3). In the circumferential direction of the paper tube 1, the grip region 2 exhibits grip property (frictional resistance) to grip the end portion (start of winding) of the sheet material 3 wound around the paper tube and prevent the sheet material 3 from idling, and has low tackiness (stickiness) to facilitate the peeling of the end portion of the sheet material 3 (plastic film) wound around the paper tube 1 in the radial direction (outside diameter direction) of the paper tube 1 (Fig. 2). By making the grip region 2 an acrylic-styrene resin film instead of adhesion by an adhesive, the tackiness is suppressed as described above.

[0016] (Paper tube 1) The above paper tube 1 winds up a plastic film, a metal foil, a cloth, or a non-woven fabric as the sheet material 3. As the paper tube 1, an existing paper tube in circulation can be adopted, and a paper tube having dimensions (diameter and length) suitable for the size of the sheet material 3 to be wound, that is, the length, width, and thickness of the sheet material 3, can be adopted. Particularly for the high-grip paper tube according to the present invention, a plastic film (resin film) is suitable as the sheet material 3 to be wound. However, it is also possible to use the high-grip paper tube according to the present invention for winding a sheet material 3 other than plastic.

[0017] (Grip region 2) In this example, the above grip region 2 is a single strip-shaped region extending along the axial direction of the paper tube 1. However, the grip region 2 may be configured not only as a continuously extending strip-shaped region but also as a region intermittently extending in the axial direction of the paper tube 1, that is, an intermittent region, or a plurality of scattered regions (illustration is omitted). Further, whether the grip region 2 is a continuously extending strip-shaped region or an intermittently extending region as described above, it may be implemented such that two or more grip regions 2 extend in parallel along the axial direction of the paper tube 1.

[0018] The grip region 2 is a resin layer provided in a range where the central angle of the paper tube 1 is 150 degrees or less in the circumferential direction of the paper tube 1. On the premise of the above central angle range, it is desirable that the line width (the length in the circumferential direction of the paper tube 1) of the line presented by the grip region 2 extending in the axial direction is 20 mm or more. However, as long as appropriate grip performance can be exhibited, it is not excluded to implement with a line width smaller than the above. However, in the axial direction of the paper tube 1, the grip region 2 may be shorter than the paper tube 1.

[0019] Taking the above acrylic resin and acrylic-styrene resin as examples of the resin of the resin layer constituting the grip region 2, the amount of the resin is preferably 11.5 g or more per square meter in terms of conversion, and the thickness of the resin layer is preferably 20 μm or less. Specifically, when forming the grip region 2 by applying (spraying) a resin liquid obtained by diluting a resin emulsion with a solid content of about 50% (by weight) so that the resin emulsion: water = 90:10 to the paper tube 1, it is desirable that the coating amount before drying exceeds 25 g in terms of per square meter. However, as long as the thickness of the resin layer after drying of the above resin liquid is 20 μm or less, more preferably 10 μm or less.

[0020] The resin of the resin layer constituting the grip region 2 is at least one solid resin of an acrylic resin, an acrylic-styrene resin, a polyurethane resin, an alkyd resin, and a silicone resin, and satisfies the following conditions.

[0021] (Conditions for the resin constituting the resin layer of the grip region 2) When the diameter of the paper tube 1 is set to 100 mm, the axial width of the paper tube 1 is set to 90 mm, and the sheet material 3 is set to biaxially stretched polypropylene (OPP) with a width of 90 mm, a thickness of 50 μm, and a winding direction length of 200 mm, a resin that satisfies the following conditions is adopted.

[0022] That is, with respect to the axial direction (longitudinal direction) of the paper tube 1, the grip region 2 is assumed to have the same length as the length of the paper tube 1. With respect to the circumferential direction of the paper tube 1, the length of the grip region 2 is 20 mm. The leading end 3a side, which is the start end side of the winding of the sheet material 3, is attached to the entire grip region 2 (Fig. 2(A)). Using an autograph, in an environment of 23 degrees Celsius and 50% RH, when gripping (clamping) and pulling a position pa that is not attached to the grip region 2 from the grip region in the radially outward direction of the paper tube (the direction of the white arrow in Fig. 2(A), i.e., upward) at a tensile speed of 20 mm per minute, the force required for peeling the sheet material in the radially outward direction of the paper tube is set to 20 N or less (peelability). The sheet material 3 is wound around the paper tube 1 by 140 mm (Fig. 2(B)). Grasping (clamping) the position pb on the rear end side of the sheet material 3 that is not wound around the paper tube 1, and at the same tensile speed of 20 mm per minute in the same environment of 23 degrees Celsius and 50% RH as above, when pulling in the radially outward direction of the paper tube 1 (the direction of the white arrow in Fig. 2(B), i.e., upward) at the position pb (precisely, the rear end 3b of the wound sheet material 3), the frictional resistance against the sliding of the sheet material on the surface of the paper tube is set to 120 N or more (holding force). The above 140 mm is the length between the leading end 3a and the rear end 3b of the sheet material 3. The length from the central position 2a of the grip region 2 in the circumferential direction of the paper tube 1 to the rear end 3b of the sheet material 3 is 130 mm (Fig. 1(B)). The length from the central position 2a of the grip region 2 in the circumferential direction of the paper tube 1 to the rear end 3b of the sheet material 3 is the length of a circumference (the outer circumference of the paper tube 1) with a central angle θ of 150 degrees with respect to the center o (central axis) of the paper tube 1.

[0023] Regarding the peelability of the above resin conditions, as shown in Fig. 2(A), it is the uppermost point on the outer circumference of the paper tube 1 fixed in a state where the central position 3a of the grip region 2 is laid horizontally with respect to the circumferential direction of the paper tube 1. Also, regarding the holding force of the above resin conditions, as shown in Fig. 2(B), the paper tube 1 is set so that the rear end 3b of the winding of the sheet material 3 wound around the paper tube 1 by the above 140 mm from the leading end 3a of the sheet material 3 becomes the uppermost point of the paper tube 1. As shown by the dashed line in Fig. 2(B), when the sheet material 3 is pulled, the rear end 3b side of the wound sheet material 3 separates from the outer peripheral surface of the paper tube 1. In each of the peelability test (Fig. 2(A)) and the holding force (gripability) test (Fig. 2(B)), the gripping length, that is, the height pt from the top of the paper tube 1 of the gripping position (clamp position) was set to 50 mm in each case.

[0024] In particular, the resin of the resin layer constituting the grip region 2 is an acrylic-styrene resin or an acrylic resin that satisfies the above conditions, with the minimum film-forming temperature (MFT) being higher than -2°C and lower than 3°C and the glass transition temperature (Tg) being higher than -10°C and 0°C.

[0025] (Matters regarding the implementation of the resin constituting the resin layer of the grip region 2) For the resin of the resin layer constituting the grip region 2, an acrylic-styrene copolymer or an acrylate ester having MFT and Tg within the above ranges is adopted. The amount of the resin constituting the grip region 2 is preferably 11.5 g or more per square meter in terms of conversion, and the thickness of the layer of the grip region is preferably 20 μm or less. However, even if it is a polyurethane resin, an alkyd resin, or a silicone resin, those having MFT and Tg within the above ranges can be adopted as the resin constituting the grip region 2.

[0026] In addition, acrylate esters include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-dimethylaminoethyl acrylate, 2-vitroxyethyl acrylate, etc. As long as the above conditions are satisfied, any acrylate ester can be adopted.

[0027] In the description of the conditions of the resin mentioned above, the biaxially stretched polypropylene (OPP) used as the sheet material 3 was exemplified to specify the properties of the resin forming the grip region 2. As the use of the paper tube 1, the sheet material 3 (product) wound around the paper tube 1 may be plastics other than OPP, metal foil, cloth, or non-woven fabric as described above. Also, regarding the width of the paper tube 1 and the grip region 2 (the length in the circumferential direction of the paper tube 1) and the dimensions of the sheet material 3 in the above description of the resin, they were exemplified to specify the properties of the resin forming the grip region 2, and may be changed to appropriate dimensions as necessary in actual implementation.

[0028] As the use of the paper tube 3, it can be used for winding film products (sheet material 3) such as for packaging, industrial use, and optical use. For example, regarding the above sheet material 3, examples of the plastics other than OPP include general-purpose films represented by PVC, PE, CPP, OPS, PVA, vinylon, polyvinylidene chloride, and PO, and high-functional films represented by acrylic, PET, nylon, PC, silicone rubber, and polyurethane.

[0029] (Method for manufacturing a high-grip paper tube according to the present invention) The above high-grip paper tube can be manufactured using the high-grip paper tube manufacturing apparatus (grip region forming apparatus) shown in FIG. 3. The high-grip paper tube manufacturing apparatus is an apparatus for forming the grip region 2 with respect to a paper tube before it is formed as a paper tube and cut to a predetermined length, or a paper tube after being cut to a predetermined length. The high-grip paper tube manufacturing apparatus may be formed separately from a conventional paper tube apparatus and attached to the conventional paper tube apparatus, or may be incorporated into the conventional paper tube apparatus as a part of a conventional general paper tube apparatus.

[0030] In this example, the above high-grip paper tube manufacturing apparatus includes a plasma irradiation apparatus 4, an inkjet apparatus 5, a spray coating apparatus 6, a separator attaching apparatus 7, and a conveyor 8. The plasma irradiation device 4, the inkjet device 5, the spray coating device 6, and the separator attaching device 7 are arranged above the conveyor 8 in order from the upstream side to the downstream side of the conveyor 8, and are positioned above the paper tube 1 transported by the conveyor 8.

[0031] The conveyor 8 constitutes a transfer line for moving the paper tube 1 along the axial direction of the paper tube 1. In the above arrangement, the plasma irradiation device 4, the inkjet device 5, the spray coating device 6, and the separator attaching device 7 are placed in the middle of the transfer path of the transfer line, and perform processing on the paper tubes being transferred respectively. That is, the plasma irradiation device 4, the inkjet device 5, the spray coating device 6, and the separator attaching device 7 perform necessary processing on the paper tube 1 from above the paper tube 1 in the middle of the feeding path of the paper tube 1 by the conveyor 8. The configuration of each part will be specifically described.

[0032] For the above conveyor 8, an existing one that can transfer the paper tube 1 straight along the longitudinal direction of the paper tube 1 may be adopted. For example, a conveyor that is generally called a trough (belt) conveyor and has a concave center in a cross-sectional view perpendicular to the transfer direction can transfer the paper tube 1 straight and stably, and is suitable for the above conveyor 8. However, as long as the above conveyor 8 can move the paper tube 1 straight and stably, a known conveyor other than the above trough conveyor may be adopted and implemented.

[0033] The paper tube 1 transferred by the conveyor 8 first passes under the plasma irradiation device 4, and the surface of the paper tube 1 is irradiated with plasma (plasma irradiation step). For the plasma irradiation device 4, a known one in circulation may be adopted. For the plasma irradiation device 4, a well-known plasma shower irradiation device that can shower the plasma on at least the part forming the grip region 2 of the paper tube 1 may be used. By irradiating the plasma with the plasma irradiation device 4, the surface of the paper tube can be modified, the adhesion to the resin on the surface of the paper tube can be enhanced, and the coating characteristics by the above resin and the marking by the inkjet device can be surely performed.

[0034] After passing under the plasma irradiation device 4 and being plasma-irradiated, the inkjet device 5 performs marking by jetting ink onto the paper tube 1 to color it (marking step) on the part that passes under the inkjet device 5 of the paper tube 1. In this example, the inkjet device 5 performs marking by pre-coloring the part that forms the grip area 2 in red. When the remaining amount of the sheet material used for winding around the paper tube 1 becomes small, the red marking can be seen through from the transparent sheet material remaining on the paper tube 1, and the consumption of the sheet material can be known. The marking is not limited to the above red color and may be colored with other colors. Also, if marking is not required, it can be implemented without using the above inkjet device 5.

[0035] The inkjet device 4 jets ink continuously or intermittently toward the paper tube 1 based on the same principle as an industrial marker or a commercially available inkjet printer. The inkjet device 4 sprays ink onto the paper tube 1 along the axial direction of the paper tube 1, and applies a linear marking extending along the axial direction or a dashed-line marking extending along the axial direction to the position on the surface of the paper tube 1 that forms the grip area 2.

[0036] Specifically for the inkjet device 4, a device called a continuous type (continuous discharge type) can be adopted. In the continuous type inkjet device 4, the ink continuously extruded from the nozzle by a pump becomes fine droplets by an ultrasonic oscillator, the ink droplets are charged by an electrode, and are bent in orbit by a deflection electrode according to the need for printing (marking) and reach the paper tube surface. The ink that is not bent by the deflection electrode is sucked into a recovery port called a gutter, returned to the ink tank, and reused.

[0037] In addition, an on-demand type, which discharges the necessary amount of ink droplets only when needed during printing (marking), may be adopted. In the above-described on-demand type inkjet device 4, capillary action is utilized for ink supply after discharge, and thus high-viscosity ink cannot be used. Therefore, the continuous type is suitable for using high-viscosity ink. The on-demand type is classified into a piezo method, a thermal method, and an electrostatic method by applying pressure to ink droplets. However, any method may be adopted as long as appropriate marking can be performed.

[0038] When the portion of the paper tube 1 marked by the inkjet device 4 passes below the spray coating device 6, the spray coating device 6 sprays a resin liquid in which an emulsion of the water-soluble resin is diluted with water onto the portion (resin spraying step). That is, the spray coating device 6 sprays the resin liquid from the spray nozzle of the spray coating device 6 onto the marked portion of the paper tube 1.

[0039] The spray coating device 6 continuously or intermittently sprays (atomizes and sprays) the resin liquid onto the paper tube 1 along the axial direction of the paper tube 1 in the same manner as the marking to the position where the marking is formed, adheres the resin liquid in a line shape extending along the axial direction, or adheres the resin liquid in a broken line shape extending along the axial direction. It is preferable to adhere the resin liquid to the surface of the paper tube 1 so as to cover the marking. In addition, it is desirable to adopt a known spray (atomizer) compatible with high-viscosity resin for the spray coating device 6.

[0040] After spraying, the resin liquid on the surface of the paper tube 1 is naturally dried at room temperature (drying step), and the grip region 2 is formed as a coating layer composed only of the solid content of the resin, that is, only the solid content of the resin. The grip region 2 is a region of a resin layer that covers the surface of the paper tube 1 as a coating layer as described above without penetrating the paper material constituting the paper tube 1.

[0041] When the region formed as the dried grip region 2 passes under the separator sticking device 7, it comes into contact with the separator (release paper) supplied by the separator sticking device 7, and the strip-shaped separator is successively stuck to the grip region 2, covering the grip region 2 (separator sticking process). The separator is wound around a bobbin (not shown) of the separator sticking device 7 and held as a web. Due to the contact with the grip region 2, the separator is successively pulled out from the bobbin and stuck to the grip region 2. Through the above-mentioned respective processes, a high-grip paper tube is completed.

[0042] Regarding the arrangement intervals of the respective devices constituting the above-mentioned high-grip paper tube manufacturing apparatus, there is no particular limitation as long as a high-grip paper tube can be appropriately manufactured (as long as an existing paper tube can be appropriately processed). In this example, the interval t1 between the plasma irradiation device 4 and the paper tube 1 on the conveyor 8 is set to 40 mm, the interval t2 between the inkjet device 5 and the paper tube 1 on the conveyor 8 is set to 50 mm, the interval t3 between the spray coating device 6 and the paper tube 1 on the conveyor 8 is set to 65 mm, the interval t4 between the spray coating device 6 and the uppermost part (each of the left and right edges) of the conveyor 8 is set to 80 mm, the interval t5 between the inkjet device 5 and the spray coating device 6 is set to 140 mm, and the interval t6 between the spray coating device 6 and the separator sticking device 7 is set to 110 mm. However, the above-mentioned intervals between the devices constituting the high-grip paper tube manufacturing apparatus are examples, and it is possible to implement with numerical values other than the above. In particular, in accordance with the dimensions of the paper tube 1 and the transfer speed of the conveyor 8, the respective intervals between the devices constituting the high-grip paper tube manufacturing apparatus may be set to appropriate sizes.

Example

[0043] Table 1 shows the examples and comparative examples of the present invention. Samples a1 to a3 are the resins of the examples, and samples b1 and b2 are the resins of the comparative examples. As shown in Table 1, the resins of samples a1 and a3 are acrylic-styrene copolymers, specifically, the resin of sample a1 has an MFT of 2 °C and a Tg of -2 °C, and the resin of sample a3 has an MFT of 0 °C and a Tg of 0 °C, respectively, both being acrylic-styrene copolymers. The resin of sample a2 is acrylic with an MFT of 0 °C and a Tg of -10 °C. The respective data of the following examples and comparative examples were obtained by using a paper tube 1 with a diameter of 100 mm (inner diameter 76 mm + thickness 12 mm) and an axial length of 90 mm (a common one used for winding OPP), setting the circumferential length of the paper tube 1 in the grip region 2 to 20 mm, and setting the axial length of the paper tube 1 to the same 90 mm as that of the paper tube 1.

[0044]

Table 1

[0045] In sample a1, a resin emulsion with a non-volatile content, i.e., a solid content, of 50.0% was employed, and a resin solution diluted so that the resin emulsion of sample a1: water = 90:10 was sprayed onto the paper tube 1 and naturally dried to form the grip region 2. In sample a2, a resin emulsion with a non-volatile content (solid content) of 49.5% was employed, and a resin solution diluted so that the resin emulsion of sample a2: water = 90:10 was sprayed onto the paper tube 1 and naturally dried to form the grip region 2. In sample a3, a resin emulsion with a non-volatile content (solid content) of 45% was employed, and a resin solution diluted so that the resin emulsion of sample a3: water = 95:5 was sprayed onto the paper tube 1 and naturally dried to form the grip region 2. In sample b1, a resin emulsion with a non-volatile content (solid content) of 58.0% was employed, and a resin solution diluted so that the resin emulsion of sample b1: water = 80:20 was sprayed onto the paper tube 1 and naturally dried to form the grip region 2. In Sample b2, a resin emulsion with a non-volatile content (solid content) of 52% was adopted, and a resin solution diluted so that the ratio of the resin emulsion to water in Sample b2 was 90:10 was sprayed onto paper tube 1 and naturally dried to form grip area 2.

[0046]

Table 2

[0047] Regarding Sample a1 in Table 1, the measurement results of the holding force (grip property) shown in Fig. 2(B) and the measurement results of the peelability (peeling property) shown in Fig. 2(A) are shown in Table 2. For the above measurements, an autograph, which is generally recognized as a universal testing machine, was used, and for both the holding force and the peelability, a tensile test was conducted in each direction shown in Fig. 2(A)(B) at a speed of 20 mm per minute. Under the temperature and humidity conditions shown in Table 2, for paper tube 1 provided with grip area 2 of Sample a1 regarding the above holding force, three tests were conducted, and as shown in Table 2, it was confirmed that in all cases, the holding force was less than 200 N (Newton) and the OPP sheet material 3 could not be peeled off. Also, for each of paper tubes 1 provided with grip area 2 of Sample a1 regarding the peelability (peeling property), three tests were conducted, and as shown in Table 2, it was confirmed that the force required for the peeling of the OPP sheet material 3 from the paper tube 1 was within the range of 5 to 10 N in all cases. From the measurement results shown in Table 2 above, it can be understood that the paper tube 1 provided with grip area 2 of Sample a1 is non-sticky, that is, its tackiness is low and suppressed, and it has a high grip property. Although the storage environment of the double-sided tape is usually 10°C to 40°C and relative humidity of 65% RH or less, as shown in Table 2, even under storage environments outside the said storage environment of the double-sided tape, namely 9°C and relative humidity of 80% RH and 50°C and relative humidity of 80% RH, Sample a1 showed the above excellent holding force and peelability. Regarding the test results of Sample a1 shown in Table 2, for the dimensions of the OPP sheet material 3 and other test conditions other than the above temperature and relative humidity, it is the same as described in the column of "Conditions of the resin constituting the resin layer in the grip area 2" and FIGS. 2(A)(B) mentioned above.

[0048]

Table 3

[0049] For each paper tube 1 having the grip area 2 of Sample a1, the center angle θ (FIG. 2(B)) of the paper tube 1 was set to 150 degrees for reference, and the measurement results of the holding force three times each for those other than 150 degrees are also shown in Table 3. In each data of the measurement test shown in Table 3, the resin emulsion of Sample a1 was diluted to a ratio of resin emulsion: water = 90:10, sprayed and dried, and the test environment was set to 23 degrees Celsius and 50% RH relative humidity. As shown in Table 3, with the center angle θ being 150 degrees, it was confirmed that a holding force was shown such that the OPP sheet material 3 could not be peeled off when the force was less than 200 N. Also, when the center angle θ was set to 120 degrees, in each case, a holding force was shown such that the OPP sheet material 3 could not be peeled off when the force was less than 200 N, and it was confirmed that when the center angle θ was 90 degrees, a force in the range of 140 N to 170 N was required to peel off the OPP sheet material 3. Regarding the test results of Sample a1 shown in Table 2, when the dimensions of the OPP sheet material 3 and the center angle θ of the test are other than 150 degrees, for the dimensions of the OPP sheet material 3 and other test conditions, it is the same as described in the column of "Conditions of the resin constituting the resin layer in the grip area 2" and FIGS. 2(A)(B) mentioned above.

[0050]

Table 4

[0051] Also, Table 4 shows the results of measuring the adhesion amount of the resin layer after drying by changing the dilution ratio of the resin liquid of Sample a1 in water and measuring the holding force and peelability. The test environment for the data shown in Table 4 was also set at 23°C and 50% RH.

[0052]

Table 5

[0053] Regarding the paper tube 1 having the grip region 2 of Sample a2 in Table 1, Table 5 shows the results of examining the holding force (where the central angle θ is 150 degrees) and peelability (adhesion angle 0 degrees) similar to those of Sample a1. The test environment for the data shown in Table 5 was also set at 23°C and 50% RH. Also, in Table 5, the measurement results for the central angle θ of 90 degrees and 120 degrees are shown together.

[0054] When the paper tube having the grip region 2 of Sample a2 was tested three times, as shown in Table 5, it was confirmed that all showed a holding force that could not peel off the OPP sheet material 3 when less than 200 N (Newton) at a central angle of 150 degrees, and the force required for peeling the OPP sheet material 3 from the paper tube 1 (peelability) was all within 5 N. It was also confirmed that when the central angle was set to 120 degrees and 90 degrees for the paper tube 1 of Sample a2, the results were almost the same as those of Sample a1. Regarding the resin of Sample a2, the dimensions of the OPP sheet material 3 and other test conditions are the same as those described in the column of "Conditions of the resin constituting the resin layer of the grip region 2" and FIGS. 2(A) and (B) above.

[0055]

Table 6

[0056] Also, Table 6 shows the results of measuring the adhesion amount of the resin layer after drying by changing the dilution ratio of the resin solution of Sample a2 in water, and measuring the holding force and peelability. The test environment for the data shown in Table 6 was also set at 23 degrees Celsius and 50% RH relative humidity.

[0057]

Table 7

[0058] Regarding the paper tube 1 provided with the grip region 2 of Sample a3 in Table 1, Table 7 shows the results of examining the same holding force (the central angle θ is 150 degrees) and peelability (adhesion angle 0 degrees) as those of Sample a1. The dilution ratio with respect to water is set such that the emulsion resin: water of Sample a3 is 95:5. The test environment for the data shown in Table 7 was set at 23 degrees Celsius and 50% RH relative humidity. Also, in Table 7, the measurement results for the central angle θ of 90 degrees and 120 degrees are also shown together.

[0059] When the paper tube provided with the grip region 2 of Sample a3 was tested three times, as shown in Table 7, it was confirmed that all showed a holding force that could not peel off the OPP sheet material 3 when less than 200 N (Newton) at a central angle of 150 degrees, and that the force required for peeling of the OPP sheet material 3 from the paper tube 1 (peelability) all fell within the range of 5 N to 10 N. It was also confirmed that when the central angle was set to 120 degrees and 90 degrees for the paper tube 1 of Sample a3, the results were almost the same as those of Samples a1 and a2. Regarding the resin of Sample a3, the dimensions of the OPP sheet material 3 and other test conditions are the same as those described in the column of "Conditions of the resin constituting the resin layer in the grip region 2" and FIGS. 2(A) and (B) above.

[0060]

Table 8

[0061] Table 8 also shows the results of measuring the adhesion amount of the resin layer after drying by changing the dilution ratio of the resin liquid of Sample a3 in water, and measuring the holding force and peelability.

[0062] Figure 4 shows the appearance of the sheet material peeled off by pulling the sheet material in the direction shown in FIG. 2(A) above, for the paper tube 1 according to the present invention having the grip region 2 formed by the resin layer of Sample a1 and a conventional double-sided tape, with the paper tube having the region where the tip of the sheet material 3 is fixed, and with the conditions other than the resin layer and the double-sided tape being the same as those of the paper tube 1 and the sheet material 3 of Sample a1 that were tested for the peelability and grip properties. As shown in Figure 4, when the sheet material was peeled off from the (high grip) paper tube of Sample a1, both the sheet material (film) and the surface of the paper tube were in as clean a state as before the sheet material was attached. That is, there was no breakage on the surface of the paper tube, and there was no clouding or sticking of paper pieces on the sheet material. On the other hand, for the paper tube with the double-sided tape, it can be confirmed from Figure 4 that after the sheet material was peeled off, there was breakage on the surface of the paper tube and broken paper scraps were attached to the sheet material.

[0063]

Table 9

[0064] The test results of the holding force and peelability for Samples b1 and b2 in Table 1 are shown in Table 9. From the test results shown in Table 9, it can be understood that for the resin layer constituting the grip region 2, Samples a1 to a3 having a glass transition temperature range of -10°C or more and 0°C or less are superior in peelability to Samples b1 and b2 having a glass transition temperature range outside this range (at -30°C and -60°C, respectively). Regarding the resins of Samples b1 and b2, the dimensions of the OPP sheet material 3 and other test conditions (including temperature and relative humidity) other than the glass transition temperature are the same as those of Samples a1 to a3 in Tables 1, 3 to 8, and are the same as those described in the column of "Conditions of the resin constituting the resin layer of the grip region 2" and FIGS. 2(A) and (B) above.

[0065] (Summary of test results) From the test results of the paper tubes 1 with the grip regions 2 of the samples a1 to a3 shown in Tables 1 to 3, Table 5, Table 7 and FIG. 4 above, in the present invention, it was found that it is possible to provide a high-grip paper tube with excellent grip properties, that is, good peelability and suppressed tackiness. Particularly, although Samples b1 and b2 are not inferior to Samples a1 to a3 in terms of grip properties (holding power), in terms of peelability, Samples a1 to a3 with a glass transition temperature in the range of -10°C or higher and 0°C or lower can more reliably suppress the force required for peeling of the sheet material 3 to 20 N or less compared to Samples b1 and b2 outside this range. It can be said that tackiness is more reliably eliminated.

Explanation of reference numerals

[0066] 1 Paper tube 2 Grip region 3 Sheet material 4 Plasma irradiation device 5 Inkjet device 6 Spray coating device 7 Separator sticking device 8 Conveyor

Claims

1. A paper tube having a grip area on its outer peripheral surface for gripping the end of a sheet material to be wound and preventing the sheet material from idling. The sheet material is any one of a plastic film, a metal foil, a cloth, and a non-woven fabric. The grip area is a strip-shaped area extending along the axial direction of the paper tube or is composed of a plurality of areas intermittently provided along the axial direction. The grip area is a resin layer on the outer peripheral surface of the paper tube, and the circumferential length of the paper tube in the grip area is 150 degrees or less with respect to the central angle of the paper tube. The resin layer constituting the grip area is a layer of a solid resin of an acrylic-styrene copolymer having a minimum film-forming temperature of 2 degrees Celsius and a glass transition temperature of -2 degrees Celsius or a minimum film-forming temperature of 0 degrees Celsius and a glass transition temperature of 0 degrees Celsius. For a paper tube set to a diameter of 100 mm and an axial width of 90 mm, the sheet material is biaxially stretched polypropylene with a width of 90 mm, a thickness of 50 μm, and a winding direction length of 200 mm. In the axial direction of the paper tube, the grip area has the same length as the length of the paper tube 1. In the circumferential direction of the paper tube, the length of the grip area is 20 mm. The leading end side, which is the starting end side of the winding of the sheet material, is attached to the entire grip area. When pulled radially outward from the grip area of the paper tube at a tensile speed of 20 mm per minute in an environment of 23 degrees Celsius and 50% RH relative humidity, the force required for peeling the sheet material in the radially outward direction of the paper tube is 5 N to 10 N. The sheet material is wound around the paper tube by 140 mm. When the position of the rear end side of the sheet material that is not wound around the paper tube is pulled radially outward of the paper tube at the above-mentioned tensile speed in the above-mentioned environment, the frictional resistance against the sliding of the sheet material on the surface of the paper tube is 200 N or more. A high-grip paper tube.

2. A paper tube having a grip area on its outer peripheral surface for gripping the end of a sheet material to be wound and preventing the sheet material from idling. The entire base sheet material is any one of a plastic film, a metal foil, a cloth, and a non-woven fabric. The grip area is a strip-shaped area extending along the axial direction of the paper tube or is composed of a plurality of areas intermittently provided along the axial direction. The grip area is a resin layer on the outer peripheral surface of the paper tube, and the circumferential length of the paper tube in the grip area is 150 degrees or less with respect to the central angle of the paper tube. The resin layer constituting the grip region is a solid acrylic layer having a minimum film-forming temperature of 0°C and a glass transition temperature of -10°C. For a paper tube set with a diameter of 100 mm and an axial width of 90 mm, the sheet material is biaxially stretched polypropylene with a width of 90 mm, a thickness of 50 μm, and a length in the winding direction of 200 mm. In the axial direction of the paper tube, the grip region has the same length as the length of the paper tube 1. The length of the grip region in the circumferential direction of the paper tube is 20 mm. The front end side, which is the start end side of the winding of the sheet material, is attached to the entire grip region. When pulling radially outward from the grip region to the paper tube at a tensile speed of 20 mm per minute in an environment of 23°C and 50% RH relative humidity, the force required for peeling the sheet material radially outward from the paper tube is 5 N or less. The sheet material is wound around the paper tube for 140 mm. When the position of the rear end side of the sheet material that is not wound around the paper tube is pulled radially outward from the paper tube at the above-mentioned tensile speed in the above-mentioned environment, the frictional resistance against the sliding of the sheet material on the surface of the paper tube is 200 N or more. A high-grip paper tube.

3. The resin of the resin layer is an acrylic-styrene copolymer. In the grip region, the amount of the resin is 11.5 g or more per square meter in terms of conversion, and the thickness of the resin layer in the grip region is 20 μm or less. The high-grip paper tube according to claim 1.

4. The resin liquid is sprayed onto the surface of the paper tube, and after spraying, the resin liquid on the surface of the paper tube is dried, so that the grip region is formed as a coating layer made of the solid content of the resin. The resin liquid contains the resin constituting the resin layer. The manufacturing method of the high-grip paper tube according to claim 1 or 2.

5. The resin liquid is a dilution of an emulsion of the water-soluble resin with water, and the grip region is formed as a coating layer made of the solid content of the resin by natural drying. The manufacturing method of the high-grip paper tube according to claim 4.

6. Prior to the spraying of the resin liquid, plasma irradiation is performed on at least the region of the surface of the paper tube where the grip region is formed. The manufacturing method of the high-grip paper tube according to claim 4.

Images