Aluminum laminated paper tube and method for manufacturing the same

Abstract

Provided is a cylindrical paper molded article that is lightweight yet excellent in durability, airtightness, and incombustibility. 【Solution means】An aluminum laminated paper tube 1 is constituted by a cylindrical middle layer 10 including one or a plurality of paper layers, an inner layer 20 including an aluminum foil provided on the inner surface side of the middle layer 10, and an outer layer 30 including an aluminum foil provided on the outer surface side of the middle layer 10.

Description

Technical Field

[0001] The present invention relates to a cylindrical paper tube laminated with aluminum foil and a method for manufacturing the same.

Background Art

[0002] Conventionally, corrugated cardboard laminated with aluminum foil has been used as a building material such as an air-conditioning duct (Patent Documents 1 and 2). For example, Patent Document 1 discloses a non-combustible corrugated cardboard in which the surface or back surface of a corrugated cardboard (core material) having a corrugated core portion formed of a combustible material is coated with aluminum foil. This non-combustible corrugated cardboard is carried into a construction site in a flat, unfolded state and can then be formed into a rectangular tube shape by folding along the creases.

[0003] Such aluminum-laminated corrugated cardboard is lightweight, yet excellent in durability, airtightness, and non-combustibility, and can be assembled into a rectangular tube shape on-site and used as an air-conditioning duct, so it has good workability at the construction site.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, although conventional aluminum-laminated corrugated cardboard is suitable for forming into a tube shape having corners such as a rectangular tube shape or other polygonal tube shapes, it has been difficult to form it into a cylindrical shape due to the nature of the corrugated cardboard. On the other hand, for example, there are also cylindrical air-conditioning ducts, so there is also a certain demand for cylindrical molded articles laminated with aluminum foil.

[0006] In addition, since conventional aluminum laminated cardboard is first manufactured as a plate-like unfolded product and then folded into a rectangular tube shape or the like for use as a duct, the length of the rectangular tube-shaped duct depends on the length of the unfolded cardboard. Since the length of the unfolded cardboard is limited according to the capacity of the manufacturing equipment, the length of the rectangular tube-shaped duct is naturally limited. For this reason, when a duct longer than the capacity of the cardboard manufacturing equipment is required, it is necessary to secure the desired length by connecting multiple ducts assembled from cardboard. However, when multiple ducts are connected, a problem occurs in that the airtightness, durability, and non-combustibility of the duct are reduced at the joints.

[0007] Therefore, an object of the present invention is to provide a cylindrical paper product that is excellent in durability, airtightness, and non-combustibility, and to provide a technique for manufacturing such a cylindrical paper product by a method that allows easy adjustment of its length. [Means for solving the problem]

[0008] The inventor of the present invention has intensively studied means for solving the problems of the conventional inventions, and has found that by using a cylindrical paper tube as a core material instead of cardboard and covering both the front and back sides of this paper tube with aluminum foil, a cylindrical paper molded product with excellent durability, airtightness, and non-flammability can be obtained. Based on the above findings, the inventor has come to the conclusion that the problems of the conventional technology can be solved, and has completed the present invention. Specifically, the present invention has the following configuration or steps.

[0009] The first aspect of the present invention relates to a paper tube 1 laminated with an aluminum foil (also referred to as an "aluminum laminated paper tube"). The aluminum laminated paper tube 1 according to the present invention has a cylindrical middle layer 10 including one or more paper layers, an inner layer 20 including an aluminum foil provided on the inner surface side of the middle layer 10, and an outer layer 30 including an aluminum foil provided on the outer surface side of the middle layer 10. Here, the "cylindrical shape" is not limited to the case where the cross-sectional shape of the hollow portion is a perfect circle, but includes those having a cross-sectional shape of the hollow portion that approximates a shape such as an ellipse, a rounded square, or an oval without corners. Thus, a cylindrical paper tube formed of one or more thick papers is adopted as the middle layer 10 (core material portion) of the aluminum laminated paper tube 1. And in the present invention, the front and back sides of this paper tube are covered with aluminum foil. By attaching aluminum foil to both sides of the paper tube in this way, a cylindrical molded product that is lightweight yet excellent in durability, airtightness, and non-combustibility can be obtained. The aluminum laminated paper tube 1 according to the present invention can be suitably used as a building material such as an air-conditioning duct.

[0010] In the aluminum laminated paper tube 1 according to the present invention, it is preferable that the inner layer 20 and the outer layer 30 include overlapping portions 20a and 30a where the aluminum foils partially overlap. By attaching the aluminum foils in this partially overlapping manner, it becomes difficult for the paper portions to be exposed on the front and back sides, so that durability, airtightness, and non-combustibility can be improved.

[0011] In the aluminum laminated paper tube 1 according to the present invention, it is preferable that the inner layer 20 and the outer layer 30 are formed by spirally winding a strip-shaped aluminum foil around the middle layer 10. By attaching the strip-shaped aluminum foil to the middle layer 10 (paper tube) by spiral winding in this way, the inner layer 20 and the outer layer 30 can be formed without gaps by a single strip-shaped aluminum foil sheet, so that the aluminum laminated paper tube 1 can be efficiently manufactured.

[0012] In the aluminum laminated paper tube 1 according to the present invention, the width (W2) of the aluminum foil forming the inner layer 20 may be shorter than the width (W3) of the aluminum foil forming the outer layer 30. In this way, by making the width of the aluminum foil forming the inner layer 20 relatively narrow, it leads to an improvement in the strength of the entire aluminum laminated paper tube 1. On the other hand, by maintaining the width of the aluminum foil forming the outer layer 30 relatively wide, the number of joints when the aluminum laminated paper tube 1 is viewed externally is reduced, so the appearance of the aluminum laminated paper tube 1 can be improved.

[0013] In the aluminum laminated paper tube 1 according to the present invention, conversely, the width (W3) of the aluminum foil forming the outer layer 30 may be shorter than the width (W2) of the aluminum foil forming the inner layer 20. In this way, by making the width of the aluminum foil forming the outer layer 30 relatively narrow, the airtightness and incombustibility of the aluminum laminated paper tube 1 can be further improved. On the other hand, by maintaining the width of the aluminum foil forming the inner layer 20 relatively wide, the amount of the aluminum foil material can be reduced or the number of winding times of the aluminum foil can be reduced, so the manufacturing cost of the aluminum laminated paper tube 1 can be suppressed.

[0014] The second aspect of the present invention relates to a method for manufacturing the aluminum laminated paper tube 1. The manufacturing method according to the second aspect of the present invention basically relates to a method for efficiently manufacturing the aluminum laminated paper tube 1 according to the first aspect described above. In the manufacturing method according to the present invention, first, an inner layer 20 is formed by spirally winding a strip-shaped aluminum foil 20' around a winding rod 40 having a circular cross-section (including a cylindrical cross-section) (first step). Next, a middle layer 10 is formed by spirally winding one or more layers of strip-shaped cardboard 10' on the inner layer 20 wound around the winding rod 40 (second step). Further, an outer layer 30 is formed by spirally winding a strip-shaped aluminum foil 30' on the middle layer 10 wound around the winding rod 40 (third step). Then, the raw tube 1' including the inner layer 20, the middle layer 10, and the outer layer 30 is cut to a predetermined length (fourth step). Thereby, a cylindrical aluminum laminated paper tube 1 of a predetermined length is obtained. In this way, by the method of spirally winding around the winding rod 40, the length of the aluminum laminated paper tube 1 can be easily adjusted from short to long by forming the cardboard middle layer 10 (paper tube), the aluminum inner layer 20, and the aluminum outer layer 30.

[0015] In the manufacturing method according to the present invention, in the step of forming the outer layer 30 (third step), it is preferable to spirally wind a strip-shaped aluminum foil on the middle layer 10 so that the side edge of the paper forming the middle layer 10 and the side edge of the aluminum foil forming the outer layer 30 do not overlap. If the boundary line (side edge) between the cardboard forming the middle layer 10 and the aluminum foil forming the outer layer 30 overlaps, there is a possibility that gas or liquid may reach the middle layer 10 beyond the outer layer 30 and further affect the inner layer 20. Therefore, by intentionally preventing the joints between the middle layer 10 and the outer layer 30 from overlapping, the durability, airtightness, and incombustibility of the aluminum laminated paper tube 1 can be maintained.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide a cylindrical paper molded article that is lightweight yet excellent in durability, airtightness, and incombustibility. Further, according to the present invention, a cylindrical paper molded article can be manufactured by a method in which its length can be easily adjusted.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below, and also includes those appropriately modified by those skilled in the art within an obvious range from the following embodiments. In the specification of the present application, “A to B” means “A or more and B or less”.

[0019] FIG. 1 shows an aluminum laminated paper tube 1 according to an embodiment of the present invention. Further, FIG. 2 shows the cross-sectional structure of the aluminum laminated paper tube 1 along the line II-II shown in FIG. 1. As shown in FIG. 1, the aluminum laminated paper tube 1 has a cylindrical shape as a whole, and a hollow 2 is formed around its central axis L. The aluminum laminated paper tube 1 mainly includes a middle layer 10, an inner layer 20 formed on the inner surface side of the middle layer 10, and an outer layer 30 formed on the outer surface side of the middle layer 10. Note that the ratio of the length in the direction of the central axis L to the diameter of the aluminum laminated paper tube 1 shown in FIG. 1 is an example, and the ratio of the length to the diameter can be appropriately changed according to its use.

[0020] The middle layer 10 is a layer serving as a core material and is formed of single or multiple layers of cardboard. As the middle layer 10, a general paper tube can be adopted. As the cardboard constituting the paper tube, for example, one or more of kraft paper, recycled paper, paperboard (coated board), laminated paper, chipboard paper, straw board, or synthetic paper can be adopted. Examples of the material of the cardboard constituting the paper tube are wood pulp such as kraft pulp and chemical pulp, recycled pulp such as waste paper pulp, non-wood pulp such as bagasse pulp and straw pulp, and synthetic resins such as polyethylene and polypropylene. From the viewpoint of improving the strength and durability of the aluminum laminate paper tube 1, it is preferable that the middle layer 10 is formed by stacking multiple layers of cardboard. For example, in the example shown in FIG. 2, the middle layer 10 is formed by joining four layers of cardboard, namely, the first layer 11, the second layer 12, the third layer 13, and the fourth layer 14, with an adhesive. Thus, the middle layer 10 can have a four-layer structure, but it is not limited thereto and may have a two-layer or three-layer structure, or it is also possible to stack five or more layers of cardboard. The total thickness of the middle layer 10 can be, for example, 3 to 20 mm, and among them, it is preferably 5 mm or more, and particularly preferably 10 mm or more. To adjust the total thickness of the middle layer 10, the number of stacked layers of cardboard and the thickness of each layer may be adjusted.

[0021] The inner layer 20 is a layer for covering the inner surface of the middle layer 10 serving as a core material and is formed of single or multiple layers of aluminum foil. By covering the entire inner surface of the middle layer 10 with aluminum foil without gaps, the durability, airtightness, and non-combustibility of the paper tube can be improved. As the aluminum foil of the inner layer 20, either pure aluminum foil or alloy aluminum foil can be adopted. Also, the thickness of the aluminum foil of the inner layer 20 is preferably 10 μm or more, more preferably 50 μm or more, and particularly preferably 100 μm or more. Specifically, the thickness of the aluminum foil is preferably 50 to 300 μm, and particularly preferably 100 to 200 μm.

[0022] The outer layer 30 is a layer for covering the outer surface of the middle layer 10 serving as the core material, and is formed of one or more layers of aluminum foil in the same manner as the inner layer 20. By covering the entire outer surface of the middle layer 10 with aluminum foil without gaps, the durability, airtightness, and non-combustibility of the paper tube are further improved. As the aluminum foil of the outer layer 30, either pure aluminum foil or alloy aluminum foil may be employed in the same manner as the inner layer 20. Also, the thickness of the aluminum foil of the outer layer 30 is preferably 10 μm or more, more preferably 50 μm or more, and particularly preferably 100 μm or more, the same as the inner layer 20. Specifically, the thickness of the aluminum foil is preferably 50 to 300 μm, and particularly preferably 100 to 200 μm.

[0023] As described above, both the inner layer 20 and the outer layer 30 are formed of aluminum foil. These aluminum foils are adhered to the middle layer 10 formed of a paper tube using an adhesive. Examples of the adhesive are epoxy resin adhesive, polyurethane adhesive, silicone-based adhesive, acrylic-based adhesive, hot melt adhesive, and contact cement. Among them, from the viewpoint of excellent durability, airtightness, non-combustibility, water resistance, and moisture resistance, it is preferable to use an epoxy resin adhesive or a polyurethane adhesive for adhering the aluminum foil to the paper tube.

[0024] Figure 3 shows an example of a method for industrially manufacturing the aluminum laminated paper tube 1. As shown in Figure 3, the manufacturing equipment for the aluminum laminated paper tube 1 includes a winding rod 40, a spiral winding machine 50, a support base 60, and a cutter 70. In Figure 3, the winding rod 40 is arranged within the range indicated by the double arrows.

[0025] As shown in Fig. 3, first, a strip-shaped aluminum foil 20' for forming the inner layer 20 is drawn out from a roll around which the strip-shaped aluminum foil is wound, and this strip-shaped aluminum foil 20' is wound obliquely around a winding rod 40 having a circular cross-section. At this time, a tension is applied to the strip-shaped aluminum foil 20' in the longitudinal direction thereof. Note that the diameter of this winding rod 40 corresponds to the diameter of the hollow 2 of the finally obtained aluminum laminated paper tube 1. Further, the cross-sectional shape of the winding rod 40 is not limited to a perfect circle, and may be a shape approximated to a circle without corners such as an ellipse, a rounded square, or an oval.

[0026] Also, this winding rod 40 is rotating in a fixed direction with its central axis as the rotation axis. Therefore, by winding the strip-shaped aluminum foil 20' obliquely around this winding rod 40, the strip-shaped aluminum foil 20' is drawn out from the roll as the winding rod 40 rotates, and gradually extends spirally in the direction of the white arrow shown in Fig. 3.

[0027] Also, when winding the strip-shaped aluminum foil 20' around the winding rod 40, in order to prevent gaps from occurring, the winding position and winding angle of the aluminum foil 20' with respect to the winding rod 40 may be adjusted so that the aluminum foils 20' partially overlap each other. As a result, an overlapping portion 20a in which the strip-shaped aluminum foil 20' partially overlaps in two layers is formed in the inner layer 20 of the finally obtained aluminum laminated paper tube 1.

[0028] Also, an adhesive such as an epoxy resin adhesive is applied entirely to the surface side (that is, the side opposite to the surface that contacts the winding rod 40) of the strip-shaped aluminum foil 20' drawn out from the roll. In addition to serving to bond the partially overlapped aluminum foils 20' to each other, this adhesive also serves to bond these aluminum foils 20' and the strip-shaped cardboard 10' when the strip-shaped cardboard 10' is placed on top of the aluminum foil 20'.

[0029] Next, as shown in FIG. 3, a strip-shaped cardboard 10' composed of a plurality of layers for forming the middle layer 10 (paper tube) is spirally wound obliquely on an aluminum foil 20' spirally wound around a winding rod 40. At this time, a tension is applied to the strip-shaped cardboard 10' in the longitudinal direction thereof. In the example shown in FIG. 3, the strip-shaped cardboard 10' is composed of four layers, namely, a first layer 11' to a fourth layer 14', in the same manner as the example shown in FIG. 2. Further, an adhesive is applied in advance between the respective layers 11' to 14' of the cardboard 10'. Therefore, by drying the adhesive after winding the cardboard 10' around the winding rod 40, the cardboard 10' is solidified spirally according to the shape of the winding rod 40 and becomes a cylindrical paper tube. As described above, since an adhesive is applied in advance to the aluminum foil 20' located on the inner surface side of the cardboard 10', the cardboard 10' and the aluminum foil 20' are joined to each other by winding the cardboard 10' on the aluminum foil 20'. Thereby, the inner surface side of the paper tube can be covered with the aluminum foil 20'.

[0030] Subsequently, as shown in FIG. 3, a strip-shaped aluminum foil 30' for forming the outer layer 30 is pulled out from a roll around which the strip-shaped aluminum foil is wound, and this strip-shaped aluminum foil 30' is spirally wound obliquely on the cardboard 10' spirally wound around the winding rod 40. At this time, a tension is applied to the strip-shaped aluminum foil 30' in the longitudinal direction thereof.

[0031] Also, when winding the strip-shaped aluminum foil 30' around the winding rod 40, in order to prevent gaps from occurring, it is advisable to adjust the winding position and winding angle of the aluminum foil 30' with respect to the winding rod 40 so that the aluminum foils 30' partially overlap each other. Thereby, an overlapping portion 30a in which the strip-shaped aluminum foil 30' partially overlaps in two layers is formed in the outer layer 30 of the final aluminum laminated paper tube 1.

[0032] In addition, an adhesive such as an epoxy resin adhesive is entirely applied to the back side of the strip-shaped aluminum foil 30' pulled out from the roll (that is, the surface that contacts the cardboard 10' wound around the winding rod 40). This adhesive not only serves to join the partially overlapped aluminum foils 30' together, but also serves to join the aluminum foil 30' and the cardboard 10' overlapped thereunder. In this way, the outer surface side of the paper tube formed by the cardboard 10' can be covered with the aluminum foil 30'.

[0033] Subsequently, with the original tube 1' composed of the aluminum foil 20' of the inner layer 20, the cardboard 10' of the middle layer 10, and the aluminum foil 30' of the outer layer 30 wound around the winding rod 40, the spiral winding machine 50 is used to wind and tighten this original tube 1'. Thereby, the adhesion state of each layer 10, 20, 30 of the original tube 1' is made stronger. This spiral winding machine 50 is a known device also used in the manufacture of general paper tubes. That is, the spiral winding machine 50 has belts attached to two rollers respectively, and by winding these belts around the winding rod 40 and each layer 10, 20, 30, the two rollers can be rotated as the winding rod 40 rotates, and at this time, a force in the direction of making each layer 10, 20, 30 more closely adhere to the original tube 1' can be applied.

[0034] Subsequently, a support base 60 for supporting the original tube 1' is provided at the end where the original tube 1' extends beyond the length of the winding rod 40. This support base 60 has the role of supporting the original tube 1' in a state where the winding rod 40 is not inserted into the hollow. By supporting the original tube 1' with the support base 60 even after passing through the winding rod 40, the original tube 1' will continue to extend along the extension line of the winding rod 40 (in the direction of the white arrow in Figure 3).

[0035] Also, as shown in FIG. 3, a gap is provided in the support base 60, and a cutter 70 is provided in this gap. This cutter 70 is a device for cutting the original tube 1' to a predetermined length. By cutting the original tube 1' with this cutter 70, individual aluminum laminated paper tubes 1 can be obtained. The position where the original tube 1' is cut by this cutter 70 can be freely adjusted. Therefore, according to the manufacturing method shown in FIG. 3, the length of the finally obtained aluminum laminated paper tube 1 can be adjusted relatively freely.

[0036] FIG. 4 schematically shows the widths of the aluminum foil 20' (inner layer 20), cardboard 10' (middle layer 10), and aluminum foil 30' (outer layer 30) that make up the original tube 1'. In FIG. 4, the width of the cardboard 10' is indicated by reference numeral W1, the width of the aluminum foil 20' is indicated by reference numeral W2, and the width of the aluminum foil 30' is indicated by reference numeral W3. In the example shown in FIG. 4, the widths W1, W2, and W3 of the respective materials 10', 20', and 30' are substantially equal (note that substantially equal means allowing an error within ±5%). Also, the cardboard 10' is composed of four layers 11' to 14', and the width of each layer is all W1 and substantially equal. In this way, by making the aluminum foil 20' forming the inner layer 20, the cardboard 10' forming the middle layer 10, and the aluminum foil 30' forming the outer layer 30 have substantially the same width, respectively, the procurement and processing of each material become easy, so the manufacturing cost of the aluminum laminated paper tube 1 can be suppressed.

[0037] As an example, the widths W1, W2, and W3 of the respective materials 10', 20', and 30' can be 80 to 150 mm, respectively. More specifically, the widths W1, W2, and W3 are 100 to 110 mm. Note that the widths W1, W2, and W3 of each material are not limited to those listed here and can be adjusted as appropriate.

[0038] Also, as shown in FIG. 4, when stacking each of the materials 10', 20', and 30', it is preferable that the side edges of a certain material and the side edges of the material above it in the thickness direction (cross-sectional direction) do not overlap. Specifically, the aluminum foil 20' forming the inner layer 20 and the cardboard 10' stacked thereon are arranged so that their side edges do not overlap with each other. Similarly, the cardboard 10' forming the middle layer 10 and the aluminum foil 30' stacked thereon are arranged so that their side edges do not overlap with each other. If the side edges of the materials arranged vertically overlap, there is a concern that the airtightness and incombustibility of the aluminum laminated paper tube 1 may decrease. Therefore, as shown in FIG. 4, it is preferable to intentionally shift the side edges of each material arranged vertically.

[0039] FIG. 5 shows a modified example of the example shown in FIG. 4. In the example shown in FIG. 5, the lateral width W2 of the aluminum foil 20' forming the inner layer 20 is shorter compared to the lateral width W1 of the cardboard 10' forming the middle layer 10 and the lateral width W3 of the aluminum foil 30' forming the outer layer 30. Specifically, the lateral width W2 of the aluminum foil 20' can be 20 - 70% or 30 - 60% with respect to the lateral width W3 (100%) of the aluminum foil 30'. By making the lateral width W2 of the aluminum foil 20' of the inner layer 20 shorter compared to the others in this way, it leads to an improvement in the strength of the entire aluminum laminated paper tube 1. On the other hand, by maintaining the lateral width of the aluminum foil 30' of the outer layer 30 wide, the number of joints when viewing the aluminum laminated paper tube 1 from the outside is reduced, so the appearance of the aluminum laminated paper tube 1 can be improved. In the example shown in FIG. 5, the lateral width W1 of the cardboard 10' and the lateral width W3 of the aluminum foil 30' are substantially equal.

[0040] Figure 6 shows another modification of the example shown in Figure 4. In the example shown in Figure 6, the width W3 of the aluminum foil 30' forming the outer layer 30 is shorter compared to the width W1 of the cardboard 10' forming the middle layer 10 and the width W2 of the aluminum foil 20' forming the inner layer 20. Specifically, the width W3 of the aluminum foil 30' can be 20 - 70% or 30 - 60% with respect to the width W2 (100%) of the aluminum foil 20'. In this way, by making the width W3 of the aluminum foil 30' of the outer layer 30 shorter compared to the others, the airtightness and non-combustibility of the aluminum laminated paper tube 1 can be further improved. On the other hand, by maintaining the width W2 of the aluminum foil 20' forming the inner layer 20 relatively wide, the amount of aluminum foil material can be reduced or the number of windings of the aluminum foil can be reduced, so the manufacturing cost of the entire aluminum laminated paper tube 1 can be suppressed. Also, the aluminum foil 20' forming the inner layer 20 is first wound around the winding rod 40 as shown in Figure 3 and serves as the base for other materials. If the width of this aluminum foil 20' is short, the overlapping portion 20a of the aluminum foil 20' will be frequently formed, increasing the unevenness, so there is a possibility of distortion and wrinkles when other materials are wound on it. From this perspective as well, it is preferable to maintain the width of the aluminum foil 20' forming the inner layer 20 relatively wide. In the example shown in Figure 6, the width W1 of the cardboard 10' and the width W2 of the aluminum foil 20' are substantially equal.

[0041] As described above, in this specification of the present application, in order to express the content of the present invention, the embodiments of the present invention have been described with reference to the drawings. However, the present invention is not limited to the above embodiments, and includes obvious modification forms and improvement forms that those skilled in the art can make based on the matters described in this specification.

Explanation of Reference Numerals

[0042] 1... Aluminum laminated paper tube 1'... Original tube 2... Hollow 10... Middle layer 10'... Cardboard 11... First layer 12... Second layer 13... Third layer 14…Layer 4 20…Inner layer 20´…Aluminum foil 20a…Overlap part 30…Outer layer 30´…Aluminum foil 30a…Overlap part 40…Winding rod 50…Spiral winding machine 60…Support stand 70…Cutter

Claims

1. a cylindrical middle layer comprising one or more spirally wound layers of kraft paper; An innermost layer including an aluminum foil provided so as to cover the entire inner surface of the intermediate layer; The outermost layer includes an aluminum foil provided so as to cover the entire outer surface of the intermediate layer. Non-flammable aluminum laminated paper tube for air conditioning ducts.

2. The inner layer and the outer layer include an overlapping portion where aluminum foil is partially overlapped. The aluminum laminated paper tube according to claim 1.

3. The inner layer and the outer layer are each formed of a strip of aluminum foil wound spirally around the middle layer. The aluminum laminated paper tube according to claim 1 or 2.

4. The width of the aluminum foil forming the inner layer is shorter than the width of the aluminum foil forming the outer layer. The aluminum laminated paper tube according to claim 3.

5. The width of the aluminum foil forming the outer layer is shorter than the width of the aluminum foil forming the inner layer. The aluminum laminated paper tube according to claim 3.

6. A method for manufacturing a non-flammable aluminum laminated paper tube for an air conditioning duct, comprising the steps of: A step of forming an innermost layer by spirally winding a strip of aluminum foil around a winding rod having a circular cross section; forming a middle layer by spirally winding one or more layers of strip-shaped kraft paper onto the inner layer wound around the winding rod; forming an outermost layer by spirally winding a strip of aluminum foil on the middle layer wound around the winding rod; cutting the original tube including the inner layer, the middle layer, and the outer layer to a predetermined length. A manufacturing method for non-flammable aluminum laminated paper tubes for air conditioning ducts.

7. The step of forming the outer layer includes winding a strip of aluminum foil spirally around the intermediate layer so that the side edges of the paper forming the intermediate layer and the side edges of the aluminum foil forming the outer layer do not overlap. A method for manufacturing the aluminum laminated paper tube according to claim 6.

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