Paper tube

Abstract

To provide a paper cylinder having a new structure.SOLUTION: A rectangular paper base material including a first surface and a second surface, the paper base material including a first bonding region located along one side of the first surface and a second bonding region located away from the one side, the first bonding region and the second bonding region being bonded to each other in a state of being bent with the first surface as an inner side to form a tubular non-bonding region, the paper substrate is wound around the non-bonded region as an axis, and the first surface and the second surface are bonded in at least a part of the wound paper substrate.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a paper tube, and more particularly to a paper tube having excellent water resistance and oil resistance. [Background technology]

[0002] Paper tubes are used as containers, reel cores, furniture materials, building materials, etc. In particular, in recent years, they have been attracting attention as an alternative to plastic containers from the viewpoints of reducing environmental impact, recyclability, etc. Paper tubes are usually formed either by spiral winding, in which a plurality of strip-shaped base paper sheets are spirally wound with offset from one another, or by flat winding, in which strip-shaped base paper sheets are wound in parallel. Whether spirally wound or flat-wound, paper tubes have problems with water resistance and oil resistance because the side edge surfaces of the paper are exposed to the inside of the paper tube, and liquids (water, oil) can penetrate through the exposed side edge surfaces, causing peeling, etc. Therefore, methods have been proposed to improve the water resistance and oil resistance of paper tubes, such as skive hemming (Patent Document 1) and a method of protecting the side edge surfaces with edge-protecting sheaves (Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 4-83637 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-233348 Summary of the Invention [Problem to be solved by the invention]

[0004] The objective is to provide a paper tube with a novel structure. Another objective is to provide a paper tube with excellent water resistance and oil resistance. [Means for solving the problem]

[0005] The means for solving the problems of the present invention are as follows. 1. A rectangular paper substrate having a first surface and a second surface, The paper substrate has a first bonding area located along one side on the first surface and a second bonding area located away from the one side, the first bonding region and the second bonding region are bonded together in a bent state with the first surface facing inward, thereby forming a cylindrical non-bonded region; A paper tube characterized in that the paper base material is wound around the non-bonded region as an axis, and the first surface and the second surface are bonded in at least a portion of the wound area. 2. The paper substrate has a heat seal layer located on the first surface side, 1. The paper tube described in 1., which is joined by heat sealing. 3. The basis weight of the paper base material is 20 g / m 2 More than 200g / m 2 The paper tube according to 1. or 2., characterized in that: 4. A paper tube according to any one of 1. to 3., characterized in that the inner surface of the paper tube is water-resistant, oil-resistant, or both. 5. The paper tube according to any one of 1. to 4., wherein the paper base material is bonded via a biodegradable resin. 6. A paper tube according to any one of 1. to 5., characterized in that it is used to contain a liquid. 7. A first joining process in which a rectangular paper substrate having a first surface and a second surface, a first joining region located along one side of the first surface, and a second joining region located away from the one side, is bent with the first surface facing inward to join the first joining region and the second joining region and form a cylindrical non-joined region; a winding step of winding the paper base material around the non-bonded region; a second joining step of joining the first surface and the second surface of at least a portion of the wound paper base material; A method for manufacturing a paper tube, comprising: 8. The paper substrate has a heat seal layer located on the first surface side, 7. The method for manufacturing a paper tube according to 7., characterized in that the joining is carried out by heat sealing. [Effects of the Invention]

[0006] The present invention can provide a novel paper cylinder and a method for manufacturing the same. In the paper tube of the present invention, the side edges of the paper are not exposed on the inside of the paper tube, so liquids do not penetrate through the side edges. Paper tubes whose inner surface (the first surface of the paper base material) is water-resistant and oil-resistant are particularly excellent at preventing liquid penetration, and can also be used for containing liquids. Paper tubes with a coated heat-seal layer can be re-disintegrated, making them easy to recycle as waste paper. Paper tubes that are bonded via biodegradable resin have very little environmental impact because both the base paper and the heat seal layer are biodegradable. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a paper substrate used in the present invention. [Figure 2] 4A to 4C are diagrams illustrating the manufacturing process of the paper cylinder of the present invention. [Figure 3] 4A to 4C are diagrams illustrating the manufacturing process of the paper cylinder of the present invention. [Figure 4] 4A to 4C are diagrams illustrating the manufacturing process of the paper cylinder of the present invention. [Figure 5] 4A to 4C are diagrams illustrating the manufacturing process of the paper cylinder of the present invention. [Figure 6] 4A to 4C are diagrams illustrating the manufacturing process of the paper cylinder of the present invention. [Figure 7] Schematic diagram of a paper tube of the present invention. [Figure 8] Schematic diagram of a cross section perpendicular to the axis of a paper tube of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] "Paper tube manufacturing method" An example of a method for manufacturing a paper tube of the present invention will be described in the order of steps with reference to the drawings. Note that the drawings do not reflect actual dimensions; for example, the paper substrate 100 is shown thicker than it actually is to facilitate understanding.

[0009] A paper substrate 100 to be used in the present invention is prepared in advance (FIG. 1). The paper substrate 100 is rectangular and has a first side 110 and a second side 120 . A first bonding region 111 and a second bonding region 112 are located on the first surface 110, and the portion sandwiched between the first bonding region 111 and the second bonding region 112 becomes a non-bonded region 113 of the paper tube. The first bonding area 111 is located along one side S of the paper base material 100. The first bonding area 111 can be located away from the side S, but it is preferable that it is located in contact with the side S to prevent winding defects such as curling. The second bonding region 112 is located away from the side S. The second bonding region 112 is a region that is bonded to the first bonding region 111 while facing the first bonding region 111, and is located parallel to the first bonding region 111 and has the same width as the first bonding region 111.

[0010] ·First joining process A core C is placed between the first bonding region 111 and the second bonding region 112 of the paper base material 100 (FIG. 2), and the paper base material is bent with the first surface 110 facing inward so as to be wound around the core C (FIG. 3), and the first bonding region 111 and the second bonding region 112 are bonded together (FIG. 4). In FIGS. 2 to 7, (a) is a perspective view, and (b) is a view seen from a direction parallel to the axial direction of the core C (the axial direction of the paper tube). In (b), the first bonding region 111 and the second bonding region 112 are shown with hatching to have a thickness, but this is merely to indicate their position; the first bonding region 111 and the second bonding region 112 are located on the first surface 110 and do not have a specific thickness. The width W1 of the first bonding region 111 (equal to the width of the second bonding region) is not particularly limited, but is preferably 1 mm or more, more preferably 2 mm or more, to ensure a strong bond. When a heat-seal layer (described later) is laminated only on the first surface 110 of the paper substrate 100, the second surface 120 (non-heat-seal layer) of the cylindrical non-bonding region 113 and the second surface 120 (non-heat-seal layer) of the first bonding region 111 or second bonding region 112 (in the winding method of this example, the second surface 120 of the first bonding region 111) will overlap in the subsequent winding process. This overlapping portion will not contribute to bonding (unbonded) in the second bonding process (described later), resulting in insufficient strength. Therefore, it is preferable to adjust this length to be equal to or less than a certain value. Therefore, the width W1 of the first bonding region 111 is preferably equal to or less than the circumference of the circumscribed circle of the inner surface of the resulting paper tube.

[0011] The first bonding region 111 and the second bonding region 112 are bonded to form a cylindrical non-bonded region 113. The distance L between the first bonding region 111 and the second bonding region 112 is the length of the inner circumference of the cylindrical non-bonded region 113, and is also approximately equal to the length of the inner circumference of the resulting paper tube. Therefore, the distance L between the first bonding region 111 and the second bonding region 112 is adjusted to be equal to or greater than the length of the inner circumference of the resulting paper tube. However, if the distance L between the first bonding region 111 and the second bonding region 112 is too long, freewheeling may occur at the beginning of winding. Therefore, the distance L between the first bonding region 111 and the second bonding region 112 is preferably 1.5 times or less, more preferably 1.4 times or less, even more preferably 1.3 times or less, and even more preferably 1.2 times or less, of the inner circumference of the resulting paper tube.

[0012] ·Winding process The paper substrate 100 is wound around the non-bonded region 113 (FIG. 5). In this manufacturing method, the paper substrate 100 is wound with the first side 110 facing inward, but the paper substrate 100 can also be wound with the second side 120 facing inward.

[0013] ·Second joining process The first surface 110 and the second surface 120 are joined together in at least a portion of the wound paper substrate 100 (FIG. 6). The wound shape is fixed by joining the first surface 110 and the second surface 120 of the wound paper base material 100. Then, it can be removed from the core C to obtain the paper tube 1 (Fig. 7). In the second joining step, it is sufficient to join at least a part of the wound paper base material 100, but from the viewpoint of improving the strength of the paper tube, it is preferable to join the entire surface. The second joining step can also be carried out simultaneously with the winding step. Since the paper tube 1 is formed by being wound around the core C, a paper tube 1 of a desired shape can be manufactured by changing the shape of the core C. The cross-sectional shape and size of the core C can be set according to the use of the paper tube 1, and can be, for example, circular, elliptical, rectangular, hexagonal, etc., and the size of the circumscribed circle can be, for example, 3 mm or more and 200 mm or less. In addition, the thickness of the side surface of the paper tube 1 can also be, for example, 100 μm or more and 50 mm or less, depending on the use of the paper tube 1, etc.

[0014] "Paper cylinder" A schematic cross-sectional view of a paper cylinder 1 of the present invention is shown in FIG. The side S of the paper tube 1 where the first bonding region 111 is located is embedded inside the wall surface of the paper tube 1 and is not exposed to the inner surface of the paper tube 1. In the paper tube 1 of the present invention, the side end surfaces of the paper base material 100 that constitutes the paper tube 1 are not exposed to the inner surface, so liquid does not penetrate from the side end surfaces.

[0015] The inner surface of the paper tube 1 is formed by the first surface 110 of the paper substrate 100. Therefore, it is preferable that at least the portion of the first surface 110 of the paper substrate 100 that will become the non-bonded region 113 has either water resistance or oil resistance, or both, and it is more preferable that the entire first surface 110 has either water resistance or oil resistance, or both. If at least the portion of the first surface 110 of the paper substrate 100 that will become the non-bonded region 113 has water resistance / oil resistance, it is possible to impart water resistance / oil resistance to the inner surface of the resulting paper tube, making it suitable for use, for example, in applications where liquids are contained. In the present invention, being water resistant means that the water absorbency according to JIS P 8140:1998 "Paper and paperboard - Test method for water absorbency - Cobb method" is 13 g / m or more. 2 Oil resistance means that the oil absorption rate when mineral oil is used instead of water in the Cobb method is 13 g / m or less. 2 Furthermore, containing a liquid means containing something that has fluidity when filled or stored, and includes, for example, something that becomes solid by freezing after being filled with a liquid, or something that is solid when filled but becomes liquid due to dissolution, seepage, condensation, etc. during storage.

[0016] Furthermore, if at least a portion of the surface that will become the outer surface of the paper tube 1 (second surface 120 in the winding method of this example) that is the opposite side to one side S and that is the width of one circumference of the paper tube has either water resistance, oil resistance, or both, then the outer surface of the paper tube 1 can also be made water resistant, oil resistant, or both. Furthermore, in this example, the side end surface of the other side of the paper substrate 100 is exposed on the outer periphery of the paper tube 1, but by folding the other side toward the surface that will become the inner side when winding the paper tube 1 (first surface 110 in the winding method of this example), the side end surface of the other side can be embedded inside the paper tube 1. With this configuration, excellent water resistance and oil resistance can also be imparted to the outer surface of the paper tube, making it suitable for use, for example, in applications where it will be immersed in liquid.

[0017] The uses of the paper tube of the present invention are not particularly limited, and can be used as, for example, containers for storing food and beverages, medicines, cosmetics, stationery, clothing, etc.; shafts of writing instruments, makeup brushes, lipstick, etc.; core members for storing ink for writing instruments; paper straws; parts for furniture, home appliances, etc.; materials for construction, civil engineering, agriculture, and horticulture, etc.; cores for windings, etc.

[0018] ·Paper base material The paper substrate 100 used in the present invention is not particularly limited as long as it can be wound to form a paper tube 1. The basis weight of the paper substrate 100 is 20 g / m 2 More than 200g / m 2 A basis weight of 20 g / m or less is preferred. 2 By setting the basis weight at 200 g / m or more, breakage during the manufacture of the paper tube can be prevented. 2 The basis weight of the paper substrate 100 is 24 g / m or less, which makes it easy to wind. 2 More preferably, 28 g / m 2 More preferably, 32 g / m 2 More preferably, 180 g / m 2 Less than 160 g / m is more preferable. 2 More preferably, 140 g / m 2 Even more preferably, 120 g / m 2 Even more preferably, 100 g / m 2 Even more preferred are the following:

[0019] The paper substrate 100 comprises at least base paper. ·Base paper The base paper is a sheet containing pulp and optionally containing fillers, auxiliaries, and the like. The pulp contained in the base paper is not particularly limited, but when the paper tube is used for applications in which it will come into contact with food and beverages that are ingested orally, chemical pulps such as LBKP and NBKP, which are less likely to be contaminated with foreign matter, are preferred, and a small amount of recycled paper pulp is also preferred. Specifically, the ratio of chemical pulp to the total pulp is preferably 70% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, and most preferably 100% by weight. Furthermore, the ratio of recycled paper pulp to the total pulp is preferably 10% by weight or less, more preferably 5% by weight or less, even more preferably 3% by weight or less, and most preferably 0% by weight.

[0020] In order to produce paper tubes with a brown appearance and natural texture, it is preferable to use unbleached pulp, such as unbleached kraft pulp (NUKP, LUKP) or mechanical pulp (GP, TMP, etc.), which does not undergo a bleaching process during the pulp manufacturing process. Paper tubes with this appearance can evoke an organic, natural feel, and an image of safety and security. When unbleached pulp is used, it is preferable to blend 70% or more by weight of unbleached pulp with respect to the total pulp, more preferably 80% or more by weight, even more preferably 90% or more by weight, and most preferably 100% by weight.

[0021] Heat seal layer By using a paper substrate 100 having a heat seal layer on at least the first surface 110, the sheets can be joined by heat sealing. It is preferable to provide a heat seal layer on both surfaces. Although the heat seal layer can be partially formed only in the area to be joined, it is preferable to provide it on the entire surface. The heat-sealing layer may be a coating layer or a laminate layer, and may have either or both water resistance and oil resistance.

[0022] The thermoplastic resin contained in the heat seal layer can be any known resin without any particular limitation. For example, polyethylene (PE), polypropylene (PP), polyvinyl alcohol (PVA), polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), polybutylene succinate (PBS), etc. can be used. Among these, biodegradable resins are preferred. Note that a biodegradable resin is a resin that can be decomposed by microorganisms into at least water and carbon dioxide, and has an aerobic biodegradation rate of 50% or more in 6 months, as measured according to a method in accordance with ISO-14855-2 (2018).

[0023] When the heat seal layer is a coated layer, the coating amount per side of the heat seal layer is 3 g / m2 in dry weight. 2 More than 20g / m 2 The coating weight per side is preferably 3 g / m2 or less in dry weight. 2 If it is less than 20 g / m, the heat sealability may be reduced. 2 Above this value, the heat sealability is almost saturated and there is almost no further improvement, resulting in an increase in costs. The heat seal layer, which is a coating layer, may be a single layer or may be composed of two or more layers. By constructing the heat seal layer with two or more coating layers, defects such as coating unevenness can be reduced compared to a single layer. When the heat seal layer is constructed with two or more coating layers, it is preferable that the total dry weight of the heat seal layers on one side is within the above range, and the dry weight coating amount per layer is 2 g / m2 or more. 2 It is preferable that this is equal to or greater than this.

[0024] The coating method is not particularly limited, and coating can be performed using a known coating device and coating system. Examples of coating devices include blade coaters, bar coaters, air knife coaters, curtain coaters, spray coaters, roll coaters, reverse roll coaters, size press coaters, and gate roll coaters. The coating system may be either aqueous coating using a solvent such as water or solvent-based coating using a solvent such as an organic solvent, but aqueous coating is preferred from the viewpoint of safety and hygiene. When using aqueous coating, a water-dispersible resin or a water-soluble resin is used as the thermoplastic resin.

[0025] When the heat seal layer is a laminate layer, the thickness of the heat seal layer is preferably 7 μm or more and 100 μm or less. If the thickness is less than 7 μm, the heat sealability may not be ensured. On the other hand, if the thickness exceeds 100 μm, it is not preferable from the viewpoint of cost. The lamination method is not particularly limited, and various methods such as extrusion lamination, wet lamination, and dry lamination can be used as appropriate.

[0026] ·glue The paper substrate 100 can also be adhesively bonded. The adhesive is not particularly limited as long as it can adhere to a paper substrate, and known adhesives can be used, including solvent-based adhesives, emulsion-based adhesives, reactive adhesives, and hot-melt adhesives. Examples of adhesive resins suitable for adhering paper include vinyl acetate-based, polyvinyl alcohol-based, starch-based, acrylic-based, and epoxy-based adhesives. Among these, water-soluble or water-dispersible adhesives are preferred because they have a low environmental impact during production and are also safe. Water-dispersible adhesives are more preferred because they can achieve a higher solids concentration than water-soluble adhesives and can shorten the time it takes for water to evaporate and adhesive strength to develop. Furthermore, biodegradable adhesives are preferred because they reduce the environmental impact. The amount of adhesive to be applied is not particularly limited as long as it is an amount that can firmly bond the paper substrate 100. For example, the amount of adhesive to be applied is 0.1 g / m2 in terms of dry weight. 2 More than 10g / m 2 The following are included: [Explanation of symbols]

[0027] 1 paper tube 100 Paper base material 110 Page 1 111 1st junction area 112 Second junction area 113 Non-bonded area 120 Side 2 S side W1 Width of the first bonding area L: Distance between the first and second bonding areas C core

Claims

1. a rectangular paper substrate having a first surface and a second surface; The paper substrate has a first bonding area located along one side on the first surface and a second bonding area located away from the one side, the first bonding region and the second bonding region are bent and bonded together with the first surface facing inward, thereby forming a cylindrical non-bonded region; The paper base material is wound around the non-bonded region as an axis, and the first surface and the second surface are bonded to each other in at least a portion of the wound paper base material.

2. the paper substrate has a heat seal layer located on the first surface side, 2. The paper tube according to claim 1, wherein the paper tube is joined by heat sealing.

3. The basis weight of the paper base material is 20 g / m ２ More than 200g / m ２ 3. The paper tube according to claim 1, wherein the following is true:

4. 3. The paper tube according to claim 1, wherein the inner surface of the paper tube is water-resistant, oil-resistant, or both.

5. 3. The paper tube according to claim 1, wherein the paper base material is bonded via a biodegradable resin.

6. 5. The paper tube according to claim 4, which is for containing a liquid.

7. a first joining step of bending a rectangular paper substrate having a first surface and a second surface, the first surface being a first joining region located along one side of the first surface, and a second joining region located away from the one side, with the first surface facing inward to join the first joining region and the second joining region and form a cylindrical non-joined region; a winding step of winding the paper base material around the non-bonded region; a second joining step of joining the first surface and the second surface of at least a portion of the wound paper base material; A method for manufacturing a paper tube, comprising:

8. the paper substrate has a heat seal layer located on the first surface side, 8. The method for manufacturing a paper tube according to claim 7, wherein the joining is performed by heat sealing.

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