JP2020065834A - Paper cylinder - Google Patents

Abstract

To provide a paper cylinder that has a reduced environmental load and excellent water resistance.SOLUTION: A paper cylinder includes: an inner layer formed by winding first rectangular base paper so that long sides thereof are opposite to each other; an outer layer formed by winding second rectangular base paper so that long sides thereof are opposite to each other; and an adhesive layer for causing the inner layer to adhere to the outer layer, where a long side opposite edge of the inner layer and a long side opposite edge of the outer layer are shifted in a circumferential direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a paper tube, and particularly to a paper tube having excellent water resistance.

Since plastic is inexpensive and easy to mold, it is widely used as a material for various products, and more than 300 million tons of plastic products are produced annually.
Many plastic products are properly disposed of, but due to poor management or illegal dumping, some of them are discharged to the environment as garbage and eventually reach the sea. It is estimated that the amount of plastic waste that flows into the ocean exceeds 8 million tons per year. Most of these plastic wastes are non-biodegradable, so most of them accumulate in the ocean, and it is predicted that by 2050, the total amount of plastics in the ocean will exceed the total amount of fish (by weight).

  The movement to prevent environmental destruction due to plastic waste has begun, and it is required to replace plastic disposable products with materials that have a low impact on the environment. Among them, plastic straws consume 500 million in the United States and more than 1 billion in the world per day, but death cases due to accidental ingestion of seabirds and sea turtles have been reported, and environmental protection groups have , Have begun an exercise calling for not to use plastic straws.

  As an alternative material for a plastic straw that has a low impact on the environment, paper is drawing attention along with biodegradable plastics. For example, Patent Documents 1 and 2 propose a paper straw.

JP, 6-133840, A JP, 2009-233348, A

  An object of the present invention is to provide a paper cylinder having a low environmental load and excellent water resistance.

Means for solving the problems of the present invention are as follows.
1. An inner layer formed by winding so that the long sides of the first rectangular base paper face each other,
An outer layer formed by winding so that the long sides of the second rectangular base paper face each other,
An adhesive layer for bonding the inner layer and the outer layer,
A paper cylinder, wherein a long side facing edge of the inner layer and a long side facing edge of the outer layer are displaced in a circumferential direction.
2. The first and second rectangular base papers have a water resistant surface and a non-water resistant surface,
The inner surface is formed from the water resistant surface of the first rectangular base paper, and the outer surface is formed from the water resistant surface of the second rectangular base paper. The paper cylinder described in.
3. The adhesive layer comprises a first adhesive layer provided on the first rectangular base paper and a second adhesive layer provided on the second rectangular base paper. And 1. Or 2. The paper cylinder described in.
4. 1. The basis weight of the first and second rectangular base papers is 50 g / m ² or more and 200 g / m ² or less. The paper cylinder according to any one of to 3.
5. The length of the short side of the first rectangular base paper is 95% or more and 99.5% or less of the length of the short side of the second rectangular base paper. ~ 4. The paper cylinder according to any one of 1.
6. 1. The inner diameter is 3 mm or more and 25 mm or less. ~ 5. The paper cylinder according to any one of 1.
7. 1. The long side facing edge of the first rectangular base paper and the long side facing edge of the second rectangular base paper are displaced by 0.5 mm or more in the circumferential direction. ~ 6. The paper cylinder according to any one of 1.

  The paper cylinder of the present invention is mainly made of paper, and has a small load on the environment. In the paper cylinder of the present invention, the long side facing edges of the inner layer and the long side facing edges of the outer layer are provided at positions displaced in the circumferential direction, so that water leakage on the wall surface of the paper tube can be prevented. As the first and second rectangular base papers, a base paper having a water-resistant surface and a non-water-resistant surface is used, and the inner surface and the outer surface of the paper tube are laminated so that they are water-resistant surfaces, and the wall surface of the paper tube It is possible to manufacture a paper cylinder having excellent water resistance in which water hardly penetrates. At this time, since the non-water resistant surfaces having excellent adhesiveness are adhered to each other, it is possible to obtain a paper cylinder in which the inner layer and the outer layer are firmly adhered and are not easily peeled off. A first adhesive layer is provided on the first rectangular base paper, a second adhesive layer is provided on the second rectangular base paper, and the first adhesive layer and the second adhesive layer are bonded together. By this, the adhesive layer can be formed in the circumferential direction without any gap, and even if there is a gap into which water can enter between the opposite edges of the long side, this water can be applied to the adhesive layer side surface of the rectangular base paper. It is possible to prevent direct contact.

FIG. 3 is a partially exploded view of the paper tube according to the embodiment of the present invention. FIG. 3 is a cross-sectional view of a paper cylinder that is an embodiment of the present invention.

<Paper tube>
The paper tube of the present invention has an inner layer formed by winding the first rectangular base paper so that the long sides thereof face each other, and an outer layer formed by winding so that the long sides of the second rectangular base paper face each other. And the long side facing edge of the inner layer and the long side facing edge of the outer layer are fixed in a state of being displaced in the circumferential direction.

FIG. 1 shows a partially exploded view of a paper cylinder which is one embodiment of the present invention, and FIG. 2 shows a sectional view thereof. 1 and 2 are schematic diagrams, and do not accurately represent the dimensions of the paper tube of the present invention.
The paper cylinder 1 which is one embodiment has an inner layer 11, an outer layer 12, and an adhesive layer 13 (not shown in FIG. 1). The inner layer 11 is made of a first rectangular base paper 110 and has long side facing edges 111 whose long sides face each other. The outer layer 12 is made of the second rectangular base paper 120 and has long side facing edges 121 whose long sides face each other. 1 illustrates the inner layer 11 so as to project from the outer layer 12 in order to facilitate understanding of the structure of the paper cylinder, the lengths of the inner layer and the outer layer of the paper cylinder of the present invention are the same.

  In the paper tube 1 which is one embodiment, the first and second rectangular base papers 110 and 120 have water resistant surfaces 112 and 122 and non-water resistant surfaces 113 and 123, respectively. The paper tube 1 has a water resistant surface 112 of the first rectangular base paper on the inner surface and a water resistant surface 122 of the second rectangular base paper on the outer surface. In the paper tube 1 which is one embodiment, both the inner surface and the outer surface exposed to the outside are formed of the water resistant surfaces 112 and 122, and it is difficult for water to permeate the inside of the wall surface of the paper tube 1, so that the water contact with It is also difficult to fluff. Further, in the paper tube 1 according to one embodiment, the non-water resistant surfaces 113 and 123, which are more excellent in adhesiveness than the water resistant surface, are bonded with the adhesive 13, so that the inner layer 11 and the outer layer 12 are separated from each other. Hard and has excellent water resistance.

  In the paper cylinder of the present invention, the long side facing edge of the inner layer and the long side facing edge of the outer layer are fixed in a state of being displaced in the circumferential direction. In the paper tube of the present invention, the long side facing edge of the inner layer and the long side facing edge of the outer layer, which are likely to cause a gap, are fixed in a state of being displaced in the circumferential direction, so that water leakage on the wall surface of the paper tube is prevented. Can be prevented. The gap between the long side facing edge of the inner layer and the long side facing edge of the outer layer is preferably 0.5 mm or more in the circumferential direction, more preferably 1.0 mm or more, and 2.0 mm or more. Is more preferable. In addition, it is preferable that the long side facing edges of the inner layer and the outer layer have a small gap between the facing long sides. It is more preferably 0.01 mm or less, and most preferably contact with no space.

The adhesive layer bonds the first rectangular base paper and the second rectangular base paper together.
The adhesive layer is provided on one or both of the first rectangular base paper and the second rectangular base paper by coating or the like. At this time, for example, if the adhesive layer is provided only on the first rectangular base paper, the adhesive layer provided on the first rectangular base paper exists between the long side facing edges of the outer layer, but There is no adhesive layer between the opposite edges of the long sides. Then, if there is a gap into which water can enter between the opposite edges of the long sides of the inner layer, the water that has entered from the gap may come into contact with the adhesive layer side surface of the second rectangular base paper.
In order to prevent water that has entered the gap between the opposite edges of the long sides from directly contacting the adhesive layer side surface of the rectangular base paper, the first adhesive layer and the second rectangular base paper on the first rectangular base paper. It is preferable that a second adhesive layer is provided on the shaped base paper and the first and second adhesive layers are bonded together. With such a configuration, the adhesive layer can be provided seamlessly in the circumferential direction of the paper cylinder, and water that has entered the gap between the long side opposing edges directly contacts the adhesive layer side surface of the rectangular base paper. It is possible to prevent contact.

  In the present invention, the length and diameter of the paper cylinder are not particularly limited, and can be appropriately adjusted according to the application. For example, since the paper tube of the present invention has excellent water resistance, it can be suitably used for food and drink such as straws and muddlers, and applications where it comes into contact with the mouth (hereinafter referred to as tableware applications). When the paper tube of the present invention is used for these tableware applications, the length may be about 12 to 25 cm and the inner diameter may be about 3 to 25 mm.

<Rectangular base paper / paper cylinder base paper>
In the present invention, the rectangular base paper is manufactured by cutting the base paper for a paper cylinder into a predetermined length (long side) and width (short side) to form a rectangular shape. The lengths of the long side and the short side of the rectangular base paper are not particularly limited, and can be appropriately adjusted according to the length and diameter of the paper cylinder to be manufactured. However, in the paper tube, the circumference of the inner layer is slightly shorter than that of the outer layer, and therefore the length of the short side of the first rectangular base paper as the inner layer is the short side of the second rectangular base paper. It is preferably 95% or more and 99.5% or less of the length. By making the length of the short side of the first rectangular base paper shorter than the length of the short side of the second rectangular base paper, narrowing the gap between the long side facing edge of the inner layer and the long side facing edge of the outer layer You can The first rectangular base paper forming the inner layer and the second rectangular base paper forming the outer layer may be the same base paper or different base papers.

The basis weight of the rectangular base paper is preferably 50 g / m ² or more and 200 g / m ² or less. When the basis weight is less than 50 g / m ² , the rigidity of the obtained paper cylinder may be insufficient. If the grammage exceeds 200 g / m ² , winding may be difficult. The basis weight of the rectangular base paper is more preferably 70 g / m ² or more and 180 g / m ² or less, and further preferably 80 g / m ² or more and 150 g / m ² or less.

  Both sides of the first and second rectangular base papers may be water resistant surfaces, but it is more preferable that one surface is a water resistant surface and the other surface is a non-water resistant surface. By using the paper tube base paper having the water resistant surface and the non-water resistant surface and bonding the non-water resistant surfaces to each other, the paper tube base paper can be firmly bonded. Further, since the outer surface and the inner surface of the obtained paper cylinder are formed of water resistant surfaces, it is possible to obtain a paper cylinder in which water hardly permeates.

Here, in the present invention, the water resistant surface means a surface having a water absorption value of 20 g / m ² or less obtained by the Cobb method (contact time 30 seconds) defined in JIS P8140, and the non-water resistant surface. , The backside of the water resistant surface and having a larger Cobb water absorption value than the water resistant surface.
The water resistant surface preferably has a water absorption value of 15 g / m ² or less, and more preferably 10 g / m ² or less. Further, the water absorption value of the non-water resistant surface is preferably 1 g / m ² or more, more preferably 3 g / m ² or more, more preferably 5 g / m ² or more, larger than the water absorption value of the water resistant surface. Is more preferable.

  As a paper cylinder base paper having a water resistant surface and a non-water resistant surface, it can be used without particular limitation, for example, only one surface of the base paper, coated with a water resistant resin, a water resistant layer by laminating etc. What was formed, what applied the coating liquid containing an externally added sizing agent, and made it a size surface etc. can be used.

-Base paper Base paper consists of pulp, fillers, various auxiliaries, etc.
When the paper tube of the present invention is used for tableware, it is preferable to use, as each material, one that has been approved as a food additive or has obtained FDA certification and is suitable for food safety.

Examples of pulp include bleached kraft pulp of conifer (NBKP), unbleached kraft pulp of conifer (NUKP), bleached kraft pulp of hardwood (LBKP), unbleached kraft pulp of hardwood (LUKP), sulfite pulp (SP), and the like. Wood chemical pulp, ground pulp (GP), refiner ground pulp (RGP), stone ground pulp (SGP), chemiground pulp (CGP), semi-chemical pulp (SCP), thermomechanical pulp (TMP), chemithermomechanical Mechanical pulp of wood such as pulp (CTMP), non-wood pulp obtained from kenaf, bagasse, bamboo, hemp, straw, etc., used paper pulp from which the ink contained in the used paper is removed in the deinking process It is possible to appropriately mix and use known pulp.
However, when the paper tube of the present invention is used for tableware, it is preferable to use chemical pulp such as LBKP and NBKP in which foreign matter is unlikely to occur, and it is preferable that the amount of used paper pulp is small. Specifically, the blending amount of the chemical pulp is preferably 80% or more, and particularly preferably 100%.

  Fillers include talc, kaolin, calcined kaolin, clay, heavy calcium carbonate, light calcium carbonate, white carbon, zeolite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica, aluminum hydroxide. , Use known fillers such as inorganic fillers such as calcium hydroxide, magnesium hydroxide, zinc hydroxide, barium sulfate and calcium sulfate, organic fillers such as urea-formalin resin, polystyrene resin, phenol resin and fine hollow particles. You can The filler is not an essential material and may not be used.

  Examples of various auxiliary agents include rosin, alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA) and other internally added size agents, polyacrylamide-based polymers, polyvinyl alcohol-based polymers, cationized starch, various modified starches, Urea / formalin resin, melamine / formalin resin and other dry paper strengthening agents, polyamide polyamine epichlorohydrin resin, polyamine epichlorohydrin resin, polyamide epichlorohydrin resin, polyvinylamine resin, polyethylene imine resin and other wet paper strength enhancers, retention agents, filters Aqueous improvers, coagulants, sulfuric acid bands, bulking agents, dyes, optical brighteners, pH adjusters, defoamers, UV inhibitors, anti-fading agents, pitch control agents, slime control agents, etc. It can be appropriately selected and used accordingly.

・ Papermaking process The method of manufacturing (papermaking) base paper and the type of papermaking machine are not particularly limited, and there are fourdrinier paper machines, twin wire paper machines, cylinder paper machines, gap formers, hybrid formers (on-top machines). A known manufacturing (papermaking) method such as a former) or a paper machine can be selected.
Further, the pH during papermaking may be any of an acidic region (acidic papermaking), a pseudo-neutral region (pseudo-neutral papermaking), a neutral region (neutral papermaking), and an alkaline region (alkaline papermaking). After that, an alkaline chemical may be applied to the surface of the paper layer.

-Water-resistant surface When a composition containing a water-resistant resin is applied to the base paper to form a water-resistant layer by coating, laminating, etc., the water-resistant resin should be a water-resistant surface that satisfies the value of water absorption according to the Cobb method described above. The obtained resin can be used without particular limitation. For example, polyethylene, polypropylene, and their derivatives such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, and vinyl chloride-vinyl acetate copolymer polyolefins, silicones, acrylics, epoxies, polyesters, cellulose. A paint containing a water-resistant resin such as a water-based resin or a urethane-based resin can be used. Of these, biodegradable water resistant resins are preferable from the viewpoint of the environment. Also, if a transparent or white waterproof layer is provided on a white base paper, defects such as pinholes are hard to find, so the waterproof layer may be colored in a color other than white by a pigment, a dye, or the like. preferable. By coating or laminating such a composition on only one side of the base paper, it is possible to manufacture a paper cylinder base paper having a water resistant surface and a non-water resistant surface.
The composition forming the water resistant layer may include a pigment, a dye, a curing agent, a leveling agent, a solvent, etc., in addition to the water resistant resin. When a solvent is contained, it is preferable that the solvent is water because it is excellent in safety.

In addition, when a size surface is formed by applying a coating liquid containing an externally added sizing agent to a base paper, as the externally added sizing agent, it is possible to obtain a water resistant surface that satisfies the value of the water absorption by the Cobb method Can be used without particular limitation. For example, various sizing agents such as rosin, alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), styrene-maleic acid copolymer, styrene-acrylic acid copolymer, and olefin can be used. By coating the coating liquid containing such an externally added sizing agent on only one surface of the base paper, it is possible to manufacture a paper cylinder base paper having a water resistant surface and a non-water resistant surface. At this time, the other surface of the base paper is not required to be coated with the coating liquid containing the externally added sizing agent, and may be coated with the coating liquid not containing the externally added sizing agent.
The concentration of the externally added sizing agent in the coating liquid can be appropriately adjusted according to the coating method and the required water resistance, but the amount of the sizing agent to be applied is 0.01 g / m ² or more and 1.0 g / m ² or more. It is preferably ² or less. In addition to the externally added sizing agent, the coating liquid containing the externally added sizing agent is usually used as a surface treatment agent for starch, oxidized starch, modified starch, carboxymethyl cellulose, polyacrylamide, polyvinyl alcohol, modified polyvinyl alcohol, etc. Water-soluble polymer, a paper strength enhancer for the purpose of improving surface strength, and the like.

<Adhesive>
The paper cylinder of the present invention has an inner layer and an outer layer bonded together with an adhesive. As this adhesive, a known adhesive can be used without particular limitation. For example, a vinyl acetate-based, polyvinyl alcohol-based, starch-based, acrylic-based, or epoxy-based adhesive can be used. Of these, water-soluble or water-dispersible adhesives are preferable because they have a small environmental load during production and can be used safely for tableware applications. Water-dispersible adhesives are water-soluble adhesives. It is more preferable than the above because the solid content concentration can be increased and the time until the water evaporates and the adhesive strength is developed can be shortened. Further, an adhesive that is biodegradable is preferable because it has a low environmental load. As described above, it is preferable to provide an adhesive layer on both the first and second rectangular base papers, but the adhesive used strongly adheres the first and second rectangular base papers. There is no particular limitation as long as it is possible, and an adhesive layer made of the same or different adhesive can be provided on each of the first and second rectangular base papers.

The coating amount of the adhesive layer is not particularly limited as long as it can firmly bond the first rectangular base paper and the second rectangular base paper, but for example, 0.1 g / m ^{2 in} dry weight. The above is 10 g / m ² or less.

-Manufacturing method The method for manufacturing the paper cylinder of the present invention is not particularly limited, and examples thereof include the following methods.
First, an adhesive layer is provided on either or both of the first and second rectangular base papers cut into a predetermined size, and these are bonded in a state shifted in the short side direction. Then, the paper cylinder can be manufactured by winding the paper in a tubular shape so that the deviation fits, and bonding the two rectangular base papers with the exposed adhesive layer.
Further, in the above method, two strip-shaped base papers are stuck together in a state of being displaced in the width direction, wound in a tubular shape so that the deviation fits, and stuck together with an adhesive, and then cut in the length direction. As a result, a paper cylinder can be manufactured. At this time, a paper cylinder can be continuously manufactured by providing a device for slitting, applying an adhesive, laminating, cylinder processing, and cutting continuously to the papermaking line.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the following examples.
"Example 1"
Obtained base paper having a basis weight of 104 g / ^{m 2,} polyethylene (Ube Maruzen Polyethylene Co., L716) was laminated to a 16g / ^{m 2,} the polyethylene side water surface, the base paper side paper tube base paper is non-waterproof surface It was Incidentally, the water absorbency by the Cobb's method (contact time 30 seconds) as defined in JIS P8140 is, water surface 0.14 g / ^{m 2,} the non-water side was 23.3 g / ^{m 2.}
From this cardboard base paper, a first rectangular base paper having a long side length of 20 cm and a short side length of 25.1 mm, a long side length of 20 cm, and a short side length of 25.8 mm. To obtain a rectangular base paper.

  After coating the non-water resistant surface of the first rectangular base paper and the second rectangular base paper with a polyvinyl acetate adhesive, shift the second rectangular base paper by 2 mm in the short side direction to form the first rectangular shape. A paper cylinder having a diameter of about 8 mm was obtained by sticking it to a base paper, winding it in a tubular shape so that this deviation fits, and bonding two rectangular base papers with the exposed adhesive layer.

"Example 2"
Instead of polyethylene, a water-resistant varnish (manufactured by Sakuramiya Chemical Co., Ltd., containing vinyl chloride-vinyl acetate copolymer) was applied at 5.1 g / m ² to form a paper cylinder base paper having a water-resistant surface. A paper cylinder having a diameter of about 8 mm was obtained in the same manner as in Example 1 except for the above. Incidentally, the water absorbency by the paper tube for Cobb method specified in the base paper of JIS P8140 (contact time 30 seconds), the water surface is 1.55 g / ^{m 2,} the non-water side was 18.9 g / ^{m 2} .

"Example 3"
A non-water resistant surface was prepared by coating oxidized starch (Japan Corn Starch SK100) at 2.1 g / m ² on one surface of a base paper having a basis weight of 80 g / m ² . Then, on the other surface of the base paper, a coating material was prepared by mixing oxidized starch (SK100, Nippon Corn Starch Co., Ltd.) and styrene acrylic sizing agent (PERGLUTIN A288, Kurita Water Industries Co., Ltd.) in a solid content weight ratio of 15: 3. A base paper for a paper cylinder was obtained by coating at 6 g / m ² to prepare a water resistant surface. A paper cylinder having a diameter of about 8 mm was obtained in the same manner as in Example 1 except that this paper for cylinder was used. Incidentally, the water absorbency by Cobb method specified in the paper tube for the base paper of JIS P8140 (contact time 30 seconds), the water surface is 18.7 g / ^{m 2,} the non-water side was 24.3 g / ^{m 2.}

"Example 4"
Paper was prepared in the same manner as in Example 3 except that the styrene acrylic sizing agent on the size side was AKD sizing agent (SEIKO PMC Co., Ltd. SE2366) and the coating amount was 2.5 g / m ^2. I got a tube. The water absorption of the size surface of the base paper for paper cylinders according to the Cobb method (contact time 30 seconds) specified in JIS P8140 was 16.7 g / m ² .

"Example 5"
A paper cylinder was prepared in the same manner as in Example 3 except that the size-modified oxidized starch was ethylene-modified polyvinyl alcohol (Kuraray Exceval RS4104), and the paper cylinder base paper with a coating amount of 2.6 g / m ² was used. Got The water absorbency of the size surface of this base paper for paper cylinders according to the Cobb method (contact time 30 seconds) specified in JIS P8140 was 14.8 g / m ² .

"Example 6"
For paper cylinders with ethylene-modified polyvinyl alcohol (Kuraray Exceval RS4104), styrene-acrylic sizing (AKD sizing) (SEIKO PMC Co., Ltd. SE2366) as the oxidized starch on the size surface and a coating amount of 2.7 g / m ² . A paper tube was obtained in the same manner as in Example 1 except that the base paper was used. The water absorbency of the size surface of this base paper for paper cylinders according to the Cobb method (contact time 30 seconds) specified in JIS P8140 was 13.6 g / m ² .

-Water resistance evaluation The paper cylinder manufactured in the above example was immersed in a cup of water at room temperature for 30 minutes, and the presence or absence of peeling was visually confirmed at the immersed portion.
All of the paper cylinders produced in Examples 1 to 6 did not cause peeling between the inner layer and the outer layer even after being immersed for 30 minutes, and could be suitably used as a paper straw.

1 Paper Tube 11 Inner Layer 111 Long Side Opposing Edge 12 of Inner Layer Outer Layer 121 Long Side Opposing Edge of Outer Layer 13 Adhesive Layer

110 first rectangular base paper 112 water resistant surface of first rectangular base paper 113 non-water resistant surface of first rectangular base paper

120 Second rectangular base paper 122 Water resistant surface of second rectangular base paper 123 Non-water resistant surface of second rectangular base paper

Claims (7)

An inner layer formed by winding so that the long sides of the first rectangular base paper face each other,
An outer layer formed by winding so that the long sides of the second rectangular base paper face each other,
An adhesive layer for bonding the inner layer and the outer layer,
A paper cylinder, wherein a long side facing edge of the inner layer and a long side facing edge of the outer layer are displaced in a circumferential direction. The first and second rectangular base papers have a water resistant surface and a non-water resistant surface,
The paper cylinder according to claim 1, wherein an inner surface is formed from the water resistant surface of the first rectangular base paper and an outer surface is formed from the water resistant surface of the second rectangular base paper.   The adhesive layer comprises a first adhesive layer provided on the first rectangular base paper and a second adhesive layer provided on the second rectangular base paper. The paper tube according to claim 1 or 2. The paper cylinder according to any one of claims 1 to 3, wherein the first and second rectangular base papers have a basis weight of 50 g / m ² or more and 200 g / m ² or less.   The length of the short side of the first rectangular base paper is 95% or more and 99.5% or less of the length of the short side of the second rectangular base paper. The paper cylinder described in any of the above.   The inner diameter is 3 mm or more and 25 mm or less, and the paper tube according to any one of claims 1 to 5.   7. The long side facing edge of the first rectangular base paper and the long side facing edge of the second rectangular base paper are displaced from each other by 0.5 mm or more in the circumferential direction. The paper cylinder according to any one of 1.

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