Core, raw material roll, and manufacturing method of raw material roll

Abstract

The present invention relates to a roll core, a raw material roll, and a manufacturing method of a raw material roll. The present invention provides a roll core or the like capable of reducing a film depression caused by a joint between cushioning materials and a level difference mark of a film caused by a level difference of a length direction end surface of the film. A roll core (100) includes a cylindrical body (10), a cushioning layer (40) covering an outer peripheral surface of the cylindrical body (10), and an adhesive member (30) disposed between the outer peripheral surface of the cylindrical body (10) and the cushioning layer (40). A 25% compression stress of the cushioning layer (40) is 80 to 120 kPa, and the cushioning layer (40) is a foamed resin layer containing 50% by mass or more of an ethylene-vinyl acetate copolymer.

Description

Technical Field

[0001] This invention relates to a core, a raw material roll, and a method for manufacturing the raw material roll. Background Technology

[0002] When transporting or storing long strips of film, the film is usually wound onto a cylindrical core to form a roll.

[0003] As described in Patent Document 1, a type of core used in this case is known to have a cylindrical body and a cushioning material covering the outer circumferential surface of the cylindrical body.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 3964892 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] However, in the past, sometimes the surface of the wound film was dented due to the seam of the buffer material on the outer circumference of the cylinder, or uneven marks were produced on the part wound on it due to the height difference of the end face of the film in the length direction.

[0009] The present invention was made in view of the above-mentioned problems, and its object is to provide a core that can reduce membrane depressions caused by seams between cushioning materials and membrane height difference marks caused by height differences of the membrane end faces along the length direction.

[0010] Methods for solving problems

[0011] One aspect of the present invention provides a core comprising a cylindrical body, a buffer layer covering the outer peripheral surface of the cylindrical body, and an adhesive member disposed between the outer peripheral surface of the cylindrical body and the buffer layer. The buffer layer has a 25% compressive stress of 80 to 120 kPa, and the buffer layer is a foamed resin layer containing 50% by mass or more of an ethylene-vinyl acetate copolymer.

[0012] The thickness of the buffer layer can be, for example, 0.5 to 3 mm.

[0013] The adhesive component can be, for example, a single-layer adhesive layer.

[0014] The adhesive component may, for example, have a pair of adhesive layers and a substrate layer disposed between the pair of adhesive layers.

[0015] The adhesive layer may be, for example, an acrylic adhesive layer.

[0016] One aspect of the invention is the winding core, for example, used for winding optical films.

[0017] One aspect of the present invention is a raw material roll comprising a core as described above and an optical film wound around the outer peripheral surface of the core.

[0018] One aspect of the present invention is a method for manufacturing a raw material roll, comprising a step of winding an optical film on the outer peripheral surface of the aforementioned roll core.

[0019] Invention Effects

[0020] According to the present invention, a core can be provided that can reduce membrane depressions caused by seams between cushioning materials and membrane height difference marks caused by height differences at the end faces along the length of the membrane. Attached Figure Description

[0021] Figure 1 This is a perspective view of the core 100 according to one embodiment of the present invention.

[0022] Figure 2 yes Figure 1 A cross-sectional view of the axial central portion of the core.

[0023] Figure 3 (a) and (b) are sectional views of an example of the adhesive member 30, respectively.

[0024] Figure 4 This is a schematic cross-sectional view illustrating the indentation YY of the film F wound on the core 100 caused by the seam Y of the laminate 50.

[0025] Figure 5 This is a schematic cross-sectional view illustrating the indentation QQ of the membrane F wound on the core 100, caused by the corner Q of the inner peripheral end IE of the membrane F.

[0026] Explanation of reference numerals in the attached figures

[0027] 10 cylindrical body, 30 adhesive components, 32 and 36 adhesive layers, 34 substrate layer, 40 buffer layer, 20 hub components, 100 core, F film. Detailed Implementation

[0028] (Roller core)

[0029] The embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a perspective view of the core 100 according to one embodiment of the present invention. Figure 2 This is a cross-sectional view of the axial center section of the core.

[0030] The core 100 of this embodiment mainly includes a cylindrical body 10, a laminated body 50 (adhesive member 30 and buffer layer 40) and a hub member 20.

[0031] The cylindrical body 10 is a cylinder with a circular cross-section. The outer diameter of the cylindrical body 10 can be, for example, 70 to 400 mm. The thickness of the cylindrical body 10 can be 2 to 10 mm. The axial length of the cylindrical body 10 can be appropriately adjusted to match the length of the wound film, for example, it can be 300 to 2500 mm.

[0032] There are no particular limitations on the material of the cylindrical body 10; for example, it can be a metal such as aluminum alloy; fiber-reinforced resin, polyvinyl chloride resin, or ABS resin. Examples of aluminum alloys include Al-Mg-Si alloys such as A6061. Examples of fibers forming the fiber-reinforced resin include paper fiber, glass fiber, and carbon fiber. Examples of resins forming the fiber-reinforced resin include epoxy resins and phenolic resins (Bakelite). These materials have high Young's modulus of elasticity, making them easy to produce strength even when lightweight.

[0033] A laminate 50 is wound around the outer circumferential surface of the cylindrical body 10 along the circumferential direction. The laminate 50 has an adhesive member 30 and a buffer layer 40 in sequence from the side of the cylindrical body 10.

[0034] The laminates 50 are wound around the cylindrical body 10 without overlapping each other. The laminates 50 have a seam Y on the outer circumferential surface of the cylindrical body 10, where one end face faces the other end face. Without the wrapping film, the interval of the seam Y, that is, the interval between the facing end faces of the laminates 50, can be the same or different along the entire axial length of the cylindrical body 10.

[0035] Regarding the maximum spacing of seam Y, in the area where the membrane is wound, it can be set to less than 5 mm, is suitable to be less than 2 mm, and is even more suitable to be less than 1 mm. In addition, the spacing of seam Y is preferably set to 0 mm, but it can also be more than 0.3 mm or more, or more than 0.5 mm.

[0036] A buffer layer 40 is provided on the cylindrical body 10 in such a way as to cover the outer circumferential surface of the cylindrical body 10. The so-called buffer layer refers to a layer that has a buffering effect, that is, it absorbs impact due to its elasticity.

[0037] The buffer layer 40 is a layer of foamed resin containing 50% by mass or more of ethylene vinyl acetate copolymer. The 25% compressive stress of the buffer layer 40 is 80-120 kPa. The buffer layer 40 may contain 70% by mass or more of ethylene vinyl acetate copolymer, or it may contain 80% by mass or more. The buffer layer 40 may contain less than 100% by mass of ethylene vinyl acetate copolymer.

[0038] The so-called 25% compressive stress is the stress required to reduce the thickness of the buffer layer 40 by 25% of the total thickness. This 25% compressive stress can be controlled using the content of the ethylene-vinyl acetate copolymer, the foaming ratio, etc. It should be noted that the 25% compressive stress is determined according to JISK 6767. The foaming ratio can be, for example, approximately 5 to 20 times.

[0039] There is no particular limitation on the thickness of the buffer layer 40; for example, it can be 0.3–10 mm, but 0.5–3 mm is more suitable. This thickness is the value measured when the stress is 0.

[0040] The adhesive member 30 is disposed between the cylindrical body 10 and the buffer layer 40. The adhesive member 30 is peelable and can be peeled off from the cylindrical body 10 together with the buffer layer 40.

[0041] exist Figure 3 In (a) and (b), each shows an example of the adhesive member 30.

[0042] Figure 3 In (a), the adhesive member 30 is a single-layer adhesive layer 32. One side of the adhesive layer 32 is in contact with the cylindrical body 10, and the other side of the adhesive layer 32 is in contact with the buffer layer 40.

[0043] Examples of adhesive layers 32 include (meth)acrylic adhesives, urethane adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, polyether adhesives, fluorinated adhesives, and rubber adhesives. Among these, (meth)acrylic adhesives are preferred from the viewpoints of transparency, adhesion, and reprocessability.

[0044] The thickness of the adhesive layer 32 can be set to, for example, 5 to 50 μm.

[0045] Figure 3 In (b), the adhesive member 30 has a pair of adhesive layers 32 and 36 and a substrate layer 34 disposed between the pair of adhesive layers 32 and 36. The upper surface of the adhesive layer 32 contacts the lower surface of the buffer layer 40, and the lower surface of the adhesive layer 32 contacts the upper surface of the substrate layer 34. The upper surface of the adhesive layer 36 contacts the lower surface of the substrate layer 34, and the lower surface of the adhesive layer 36 contacts the outer peripheral surface of the cylindrical body 10. The thickness and material of the adhesive layers 32 and 36 in this configuration can be set to be similar to... Figure 3 The adhesive layer 32 is the same as that in (a). It should be noted that the thickness and material of the adhesive layer 32 and adhesive layer 36 can be the same or different from each other.

[0046] The substrate layer 34 may include, for example, polyolefin resins such as polyethylene and polypropylene; cyclic polyolefin resins such as norbornene polymers; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; (meth)acrylic acid resins such as poly(meth)acrylate and poly(meth)acrylate; cellulose ester resins such as triacetyl cellulose, diacetyl cellulose and cellulose acetate propionate; vinyl alcohol resins such as polyvinyl alcohol and polyvinyl acetate; polycarbonate resins; polystyrene resins; polyaryl ester resins; polysulfone resins; polyethersulfone resins; polyamide resins; polyimide resins; polyetherketone resins; polyphenylene sulfide resins; polyphenylene ether resins; and blends and copolymers thereof.

[0047] The thickness of the substrate layer 34 can be 1–100 μm, with 20–50 μm being suitable.

[0048] In such Figure 3 When the adhesive component 30 shown in (a) is a single layer, it is easy to manufacture due to its simple structure, which can reduce the manufacturing cost of the core.

[0049] On the other hand, in such Figure 3 In the case where the adhesive member 30 shown in (b) has a three-layer structure, since a material with strong adhesion to the buffer layer 40 can be used as the adhesive layer 32, and a material with strong adhesion to the cylinder 10 can be used as the adhesive layer 36, the bonding strength between the buffer layer 40 and the cylinder 10 is easily improved. Furthermore, when the worn buffer layer 40 is peeled off from the cylinder 10 after the core has been used, the buffer layer 40 is less prone to breakage due to the presence of the substrate layer 34, and can be easily peeled off from the cylinder 10 together with the substrate layer 34. Therefore, the re-application of the buffer layer 40 becomes easy, and the reuse of the cylinder 10 is also facilitated.

[0050] exist Figure 1 In the cylindrical body 10, hub members 20 are respectively embedded at both ends along the axial direction. The hub member 20 has a large-diameter cylindrical portion 22 housed within the cylindrical body 10 and a small-diameter cylindrical portion 24 with an outer diameter smaller than that of the large-diameter portion. By increasing the outer diameter of the large-diameter cylindrical portion 22 without changing the outer diameter of the small-diameter cylindrical portion 24 at both ends of the hub member 20, the radius of curvature of the membrane in the wound state can be increased, making it easier to suppress membrane curling and unevenness marks.

[0051] The material of the hub component 20 can be appropriately selected in the same way as the cylindrical body.

[0052] (Manufacturing method of the core)

[0053] Next, an example of the manufacturing method of the aforementioned core 100 will be described.

[0054] Prepare a laminate 50 containing a buffer layer 40 and an adhesive member 30, as well as a cylindrical body 10. The outer adhesive surface of the adhesive member 30 of the laminate 50 is suitable for pre-protection with a release sheet. The laminate 50 is pre-cut to the size of one circumference of the outer perimeter of the cylindrical body 10 × the axial length of the cylindrical body.

[0055] Peel off the release sheet from the adhesive side of the cut-out laminate 50, and attach the laminate 50 to the outer peripheral surface of the cylindrical body 10. At this time, the laminate 50 is attached to the outer peripheral surface of the cylindrical body 10 in a manner that the end faces of the laminate 50 face each other and the laminates do not overlap. By operating in this manner, the aforementioned core 100 can be manufactured.

[0056] Various films can be wound onto the core 100 in this embodiment. Examples of films include optical films such as polarizers, retardation films, and protective films. The material of the protective film can be the same as that of the substrate layer 34 described above. The thickness of the optical film can be, for example, 25 to 300 μm. The length of the film can be, for example, 30 to 10,000 m.

[0057] By winding a film on the outer circumferential surface of the buffer layer 40 of this type of core 100, raw material rolls of various films can be obtained.

[0058] (Effects)

[0059] According to the core of this embodiment, since the foamed resin layer with a specific 25% compressive stress and a specific composition serves as a buffer layer, it is possible to reduce the indentation of the film caused by the seams between the buffer materials and the height difference marks of the film caused by the height difference of the end face in the length direction of the film.

[0060] The present invention is not limited to the above-described embodiments, and various modifications can be adopted.

[0061] For example, the shape is not limited to that of a cylindrical body, hub component, etc., and can be appropriately deformed to match the support device of the core used. In addition, the core may not have a hub component.

[0062] Example

[0063] (Example 1)

[0064] Prepare an aluminum alloy cylindrical body with an outer diameter of 252mm and a length of 1360mm. Fix wheel hub components to both ends of the cylindrical body.

[0065] A foamed resin layer (sponge sheet: 2 mm thick) containing 94% by mass of ethylene vinyl acetate copolymer was prepared as a cushioning layer. The 25% compressive stress of this cushioning layer was 100 kPa.

[0066] An acrylic adhesive layer (20 μm thick) with a release sheet is adhered to the buffer layer to obtain a laminate. The laminate is cut to match the area of ​​the outer circumferential surface of the cylinder. The release sheet is peeled off from the cut laminate, and the buffer layer is adhered to the outer circumferential surface of the cylinder via the adhesive layer to obtain the core of Example 1. The gap of the seam Y is 1 mm.

[0067] A 148 μm thick, 1600 μm polarizing film was wound onto a core to obtain a raw material roll of polarizing film. The raw material roll was then left to stand for 30 days.

[0068] (Example 2)

[0069] Except for using a foamed resin layer containing 60% by mass of ethylene vinyl acetate copolymer as a buffer layer, the configuration is the same as in Example 1. The 25% compressive stress of this buffer layer is 105 kPa.

[0070] (Comparative Example 1)

[0071] Except for using a foamed resin layer containing 65% by mass of ethylene vinyl acetate copolymer as a buffer layer, the configuration is the same as in Example 1. The 25% compressive stress of this buffer layer is 130 kPa.

[0072] (Comparative Example 2)

[0073] Except for using a foamed resin layer containing 60% by mass of ethylene vinyl acetate copolymer as a buffer layer, the configuration is the same as in Example 1. The 25% compressive stress of this buffer layer is 70 kPa.

[0074] (Comparative Example 3)

[0075] Except for using a foamed resin layer containing 90% by mass of polyolefin as a buffer layer, it is configured the same as in Example 1. The 25% compressive stress of this buffer layer is 34 kPa.

[0076] (evaluate)

[0077] After placement, the entire polarizing film was pulled out from the raw material roll. The condition of the surface of the inner circumferential end of the film was visually inspected.

[0078] (The indentation of the membrane caused by seam Y)

[0079] Due to the seam Y of the buffer layer 40, in the membrane F, as... Figure 4As shown, recesses YY extending linearly along the axial direction of the core 100 are formed in the membrane F at approximately constant intervals in the circumferential direction. These recesses YY are formed from the inner circumferential end of the membrane F winding towards the outer circumferential end within a specified length in the circumferential direction. The circumferential length range of the membranes with formed recesses YY was visually determined for each embodiment and comparative example. Cases with lengths less than 5 m are designated as A, cases with lengths of 5 m or more but less than 10 m are designated as B, and cases with lengths of 10 m or more are designated as C.

[0080] (Elevation difference marks)

[0081] like Figure 5 As shown, the inner circumferential end IE of the membrane F is fixed to the laminate 50 (buffer layer) by double-sided adhesive tape T. Because the membrane F wound on the inner circumferential end IE is pressed against the height difference (angle Q) of the end face of the inner circumferential end IE, a linear mark (called a height difference mark QQ) extending axially along the core is formed in the membrane F due to the angle Q of the end face. This height difference mark QQ is formed from the inner circumferential end of the membrane F towards the outer circumferential end within a specified length along the circumferential direction. The circumferential length range in which the height difference mark QQ is formed was visually determined for the membranes of each embodiment and comparative example. Cases with a length less than 5m are designated as A, cases with a length of 5m or more but less than 10m are designated as B, and cases with a length of 10m or more are designated as C.

[0082] (Transformation)

[0083] Deformation of the membrane, excluding dents and unevenness marks, was observed visually.

[0084] Let A be the case where the film is deformed except for depressions and unevenness marks, B be the case where the morphology of the buffer layer is transferred to the film, and C be the case where wrinkles are generated throughout the film.

[0085] The results are shown in Table 1.

[0086] [Table 1]

[0087]

[0088] According to the embodiments, it has been confirmed that the indentation of the membrane caused by the seams between the buffer materials and the height difference marks of the membrane caused by the height difference of the end face in the length direction of the membrane can be reduced, and the deformation of the membrane other than these is not easily generated.

Claims

1. A roll core comprising a cylindrical body and a laminate, the laminate having a cushion layer covering an outer circumferential surface of the cylindrical body, and an adhesive member disposed between the outer circumferential surface of the cylindrical body and the cushion layer, the laminate being wound along a circumferential direction on the outer circumferential surface of the cylindrical body, and having a joint where one end surface faces another end surface on the outer circumferential surface of the cylindrical body, a maximum interval of the joint being 5 mm or less, a 25% compression stress of the cushion layer being 80 kPa to 120 kPa, the cushion layer being a foamed resin layer containing 50% by mass or more of an ethylene-vinyl acetate copolymer.

2. The roll core according to claim 1, wherein a thickness of the cushion layer is 0.5 mm to 3 mm.

3. The roll core according to claim 1 or 2, wherein the adhesive member is a single adhesive layer.

4. The roll core according to claim 1 or 2, wherein the adhesive member has a pair of adhesive layers and a base material layer disposed between the pair of adhesive layers.

5. The roll core according to claim 3, wherein the adhesive layer is an acrylic adhesive layer.

6. The roll core according to claim 4, wherein the adhesive layer is an acrylic adhesive layer.

7. The roll core according to claim 1 or 2, which is used for winding of an optical film.

8. A raw material roll comprising the roll core according to any one of claims 1 to 7, and an optical film wound on the outer circumferential surface of the roll core.

9. A method for manufacturing a raw material roll, comprising a step of winding an optical film on the outer circumferential surface of the roll core according to any one of claims 1 to 7.

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