JP2017065927A - Web material winding method and winding core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce step marks due to a compression stress difference generated in the surface of a web material at a winding end of a web material when winding the web material around a winding core provided with a buffer material in the outer peripheral surface.SOLUTION: A winding method of a web material of this invention includes a step of sticking an end of a web material 30 on a buffer material 20 formed on the outer peripheral surface of a winding core body 10 and a step of winding the web material around the winding core body while adding tension to the web material, the buffer material consisting of a soft foam resin with a compression stress of 0.02 MPa or less under a compression strain of 20%, the thickness (t) of the buffer material set to 0.2≥t/t≥0.1 when the thickness of the web material is t, and the buffer material having a relation of σ/σ≤6 when compression strain is σunder a compression strain of α% (20≤α≤60) and compression strain is σat a compression strain of α% (α+t/t×100)%.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a winding method for winding a web material around a winding core, and a winding core for winding the web material.

  In order to wind up a web material such as a film or a sheet in a roll shape, a method is generally used in which the tip of the web material is fixed to the outer peripheral surface of a cylindrical core with an adhesive or the like, and then the core is rotated and wound. It has been.

  By the way, since the surface of the core is generally hard, when a web material having plasticity is wound into a roll, a step is generated between the outer peripheral surface of the core and the winding end of the web material. An irreversible deformation occurs due to the level difference in the web material wound around. And since the same deformation is also transferred to the web material wound around the deformed web material, there is a problem that an irreversible step mark such as a distortion occurs in the web material over several to several tens of laps from the beginning of winding. was there. Generation | occurrence | production of such a level | step difference will reduce the flatness of a web material, and has become a cause of a product loss and cost increase.

  In order to reduce the occurrence of such step marks, Patent Document 1 discloses a technique of providing a cushioning material on the outer peripheral surface of the core. According to this technique, since the step by the thickness of a web material is relieve | moderated because the winding edge part of a web material sinks in a buffer material, a level | step difference trace can be reduced.

JP 2005-1624378 A

  However, in the conventional method, even when a soft material is used for the cushioning material, as described later, due to the difference in compressive stress when the web material is wound around the winding core at the winding end of the web material, There is a difference in the amount of subsidence, and as a result, there is a new step mark (hereinafter referred to as “step mark due to compressive stress difference”) different from the step mark caused by the end step of the conventional web material. It has arisen as a serious problem.

  The present invention has been made in view of the above problems, and its main purpose is to wind the web material around a winding core provided with a cushioning material on the outer peripheral surface as a measure against a step mark caused by an end step of the web material. At the same time, it is to reduce a level difference mark due to a difference in compressive stress, which is a new problem occurring on the surface of the web material at the winding end of the web material.

A web material winding method according to the present invention is a winding method for winding a web material around a winding core, and the winding core has a cushioning material formed on the outer peripheral surface of the winding core body. The step of attaching the end of the web material and the step of winding the web material around the core body while applying tension to the web material, and the cushioning material has a compressive stress of 0% at a compressive strain of 20%. 0.02 MPa or less of soft foamed resin, and the thickness (t ₁ ) of the cushioning material is set to 0.2 ≧ t ₂ / t ₁ ≧ 0.1, where t ₂ is the thickness of the web material to be wound. In the compressive stress-strain curve, the buffer material has a compressive stress at a compressive strain of α% (20 ≦ α ≦ 60) as σa and _a compressive stress at _a compressive strain of (α + t ₂ / t ₁ × 100)%. When σ _b , σ _b / σ _a ≦ 6.

In a preferred embodiment, the thickness (t ₁ ) of the cushioning material is set to 0.15 ≧ t ₂ / t ₁ ≧ 0.1, where t ₂ is the thickness of the web material to be wound, cushioning material, compressive stress - in strain curve, the compressive stress in the compressive strain α% (20 ≦ α ≦ 65 ) and sigma _a compressive strain compressive stress in _{(α + t 2 / t 1} × 100)% σ b Σ _b / σ _a ≦ 4.

  According to the present invention, when the web material is wound around the winding core provided with a cushioning material as a measure against a step mark caused by the end step of the web material on the outer peripheral surface, the web material is wound at the winding end of the web material. The step mark due to the difference in compressive stress generated on the surface of the film can be reduced.

(A)-(d) is the expanded sectional view which showed typically the process of winding up a web material on the conventional winding core. It is the graph which showed the compressive stress-distortion curve of the conventional buffer material. It is sectional drawing which showed typically the structure of the winding core in one Embodiment of this invention. (A)-(e) is the expanded sectional view which showed typically the process of winding up a web material on the winding core in one Embodiment of this invention. It is the graph which showed the compressive stress-strain curve of the buffer material in one Embodiment of this invention. It is the graph which expanded and showed a part of compressive stress-strain curve of the shock absorbing material in one Embodiment of this invention. It is the photograph which image | photographed the surface of the shock absorbing material when coin was pressed on the surface of the shock absorbing material used for the Example of this invention, and the shock absorbing material was sunk to 85% of compression distortion, and the coin was removed.

  Before describing the embodiments of the present invention, the background to the idea of the present invention will be described.

  1A to 1D are enlarged cross-sectional views schematically showing a process of winding a web material around a conventional winding core. The core includes a cylindrical core body and a buffer material formed on the outer peripheral surface of the core body. In FIGS. 1A to 1D, the core body is omitted, and only the cushioning material 20 formed on the outer peripheral surface of the core body is displayed. Further, the curvature of the surface of the buffer material 20 is omitted.

  FIG. 1A shows a state in which the end of the web material 30 is attached to the surface of the cushioning material 20. Here, a case where the thickness of the buffer material 20 is 500 μm and the thickness of the web material 30 is 100 μm will be described as an example.

As shown in FIG. 1B, when the web material 30 is wound around the cushioning material 20 while applying tension to the web material 30, when the cushioning material 20 is made of a soft material, It sinks into the cushioning material 20 by the thickness. At this time, the thickness of the region 20a of the cushioning material 20 in which the web material 30 sinks is 400 μm (compression strain is 20%). However, since the compressive strain of the buffer material 20 is elastic deformation, the buffer material 20 in contact with the end of the web material 30 is dragged by the sink of the web material 30 and sinks in the same manner. The cushioning material 20 in a region slightly away from the end of the stub does not sink. As a result, as shown in FIG. 1B, a groove 40 is formed on the surface of the cushioning material 20 in contact with the end of the web material 30 of the cushioning material 20. The web member 30 receives a compressive stress σ ₁ at a compressive strain of 20% from the buffer member 20.

As illustrated in FIG. 1C, when the second layer web material 30 </ b> B is wound on the first layer web material 30 </ b> A, the web material 30 further sinks into the buffer material 20. At this time, if the thickness of the region 20a of the cushioning material 20 in which the overlapping portion of the first layer web material 30A and the second layer web material 30B sinks is 200 μm, the compressive strain of the region 20a is 60%. Become. On the other hand, the thickness of the region 20b of the cushioning material 20 in which the web material 30B of the second layer is submerged is 300 μm, and the compressive strain of the region 20b is 40%. Therefore, the web material 30 in the portion where the first-layer web material 30A and the second-layer web material 30B overlap each other receives a compressive stress σ ₃ at 60% compressive strain from the cushioning material 20. On the other hand, the web material 30 having only the second-layer web material 30 </ b> B receives the compressive stress σ ₂ at the compression strain of 40% from the buffer material 20.

However, as shown in FIG. 2, the cushioning material 20 usually has a characteristic that the compressive stress increases as the compressive strain increases in the compressive stress-strain curve. Therefore, as shown in FIG. 1C, the compressive stress σ ₃ (compression strain 60%) received by the web material 30 in the portion where the first-layer web material 30A and the second-layer web material 30B overlap, There is a large difference from the compressive stress σ ₂ (compression strain 40%) received by the web material 30 of only the second-layer web material 30B. Therefore, the web material 30 having only the second-layer web material 30B is more likely to sink than the web material 30 where the first-layer web material 30A and the second-layer web material 30B overlap. As a result, as shown in FIG. 1C, there is a step between the surface of the first layer web material 30A in the region 20a and the surface of the buffer material 20 in the region 20b at the end of the first layer web material 30A. 50 will occur. Further, due to the step 50, a step 50 is also generated on the surface of the second-layer web material 30B at the end of the first-layer web material 30A.

Further, as shown in FIG. 1D, when the third layer web material 30 </ b> C is wound on the second layer web material 30 </ b> B, the web material 30 further sinks into the buffer material 20. At this time, if the thickness of the region 20a of the cushioning material 20 in which the overlapped portions of the first to third layer web materials 30A to 30C are sunk is 100 μm, the compressive strain of the region 20a is 80%. On the other hand, the thickness of the region 20b of the cushioning material 20 in which the overlapped portions of the second layer and the third layer web materials 30B and 30C sink is 200 μm, and the compressive strain of the region 20b is 60%. Therefore, the web material 30 in the portion where the first to third layer web materials 30 </ b> A to 30 </ b> C overlap receives the compressive stress σ ₅ at the compression strain of 80% from the buffer material 20. On the other hand, the web material 30 in the portion where the second-layer and third-layer web materials 30 </ b> B and 30 </ b> C overlap each other receives a compressive stress σ ₄ at 60% compressive strain from the buffer material 20.

Accordingly, as shown in FIG. 2, the compressive stress σ ₅ (compression strain 80%) received by the web material 30 in the portion where the web materials 30A to 30C of the first layer to the third layer are overlapped, and the second and third layers. There is an even greater difference from the compressive stress σ ₄ (compressive strain 60%) received by the web material 30 where the web materials 30B, 30C overlap. Therefore, the web material 30 in the portion where the first to third layer web materials 30A to 30C overlap is submerged than the web material 30 where the second and third layer web materials 30B and 30C overlap. It becomes easy. As a result, as shown in FIG. 1 (d), at the end of the first-layer web material 30A, the surface of the first-layer web material 30A in the region 20a and the surface of the buffer material 20 in the region 20b A larger step 50 is produced. Therefore, at the end of the first layer web material 30A, the web material 30 is wound while the step 50 remains on the surface of the second and third layer web materials 30B and 30C.

  As described above, as a measure against a step mark caused by an end step of the conventional web material, even when the soft cushioning material 20 is provided on the outer peripheral surface of the core body, the first to n-th layer web materials 30 overlap. If there is a large difference between the compressive stress received by the portion and the compressive stress received by the portion where the second to n-th layer web materials 30 overlap, the second layer is formed at the end of the first layer web material 30A. The web material 30 is wound while the step 50 is generated on the surface of the web material 30 in the nth layer. As a result, a step mark due to a difference in compressive stress similar to the step mark caused by the end step of the conventional web material 30 is generated in the web material 30.

  In addition, although the level difference trace by such a compressive stress difference is a level which can be discovered by careful visual inspection by a skilled person, for example, when a level difference trace due to such a compressive stress difference occurs in a thin film optical film or the like. Since this leads to quality degradation not only as a geometric distortion but also as an optical distortion, it is an especially important problem to be solved.

  From this knowledge, the inventor of the present application, as a cushioning material, the compressive stress received by the overlapping portion of the first to n-th layer web materials 30 and the second to n-th layer web materials 30 overlapped. By using a material having a small difference from the compressive stress received by the portion, the step 50 generated on the surface of the second-layer to n-th web material 30 at the end of the first-layer web material 30 is reduced. The present inventors have come up with the present invention by thinking that step marks due to the difference in compressive stress can be reduced.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment. Moreover, it can change suitably in the range which does not deviate from the range which has the effect of this invention.

  FIG. 3 is a cross-sectional view schematically showing the configuration of the core 1 in one embodiment of the present invention. As shown in FIG. 3, the core 1 in the present embodiment has a cushioning material 20 formed on the outer peripheral surface of a cylindrical core body 10.

  In the present embodiment, the cushioning material 20 is attached to the end portion of the web material 30 on the cushioning material 20, and when the web material 30 is wound around the core body while applying tension, the end portion of the web material 30. However, it is preferable to be made of a material soft enough to sink into the buffer material 20. As the material of the buffer material 20 having such characteristics, a soft foam resin having a compressive stress of 0.02 MPa or less at a compressive strain of 20% is suitable. Here, the compressive stress is a value measured according to JISK6767. If the cushioning material 20 is made of a material having a compressive stress of more than 0.02 MPa at a compression strain of 20%, the amount of sinking of the web material 30 into the cushioning material 20 is insufficient, and the end step of the conventional web material is reduced. It is not possible to sufficiently reduce the level difference caused by.

  The buffer material 20 can be formed on the outer peripheral surface of the core body 10 by applying an adhesive or the like to the outer peripheral surface of the core body 10 or the surface of the buffer material 20, for example. Or you may affix the buffer material 20 on the outer peripheral surface of the core main body 10 via a double-sided adhesive tape.

  4A to 4D are enlarged cross-sectional views schematically showing a step of winding the web material 30 around the core 1 in the present embodiment. 4A to 4D, the core body 10 is omitted, and only the cushioning material 20 formed on the outer peripheral surface of the core body 10 is displayed. Further, the curvature of the surface of the buffer material 20 is omitted.

  FIG. 4A shows a state in which the end portion of the web material 30 is attached to the surface of the cushioning material 20. Here, as in FIG. 1A, the case where the thickness of the cushioning material 20 is 500 μm and the thickness of the web material 30 is 100 μm will be described as an example, but the thickness of the cushioning material 20 and the thickness of the web material 30 are Of course, it is not limited to these sizes.

  In addition, sticking the edge part of the web material 30 to the buffer material 20 surface is performed by sticking an adhesive tape on the surface of the buffer material 20, and sticking the edge part of the web material 30 to this adhesive tape, for example. Can do. Alternatively, as the buffer material 20, a material having a sticky surface may be used.

As illustrated in FIG. 4B, when the web material 30 is wound around the cushioning material 20 while applying tension to the web material 30, the web material 30 sinks into the cushioning material 20 by the thickness. At this time, the thickness of the region 20a in which the web material 30 of the cushioning material 20 sinks is 400 μm (compression strain is 20%). Then, the web material 30 receives a compressive stress σ ₁ at a compressive strain of 20% from the buffer material 20.

As shown in FIG. 4C, when the second layer web material 30 </ b> B is wound on the first layer web material 30 </ b> A, the web material 30 further sinks into the buffer material 20. At this time, if the thickness of the region 20a of the cushioning material 20 in which the overlapping portion of the first layer web material 30A and the second layer web material 30B sinks is 200 μm, the compressive strain of the region 20a is 60%. Become. On the other hand, the thickness of the region 20b of the cushioning material 20 in which the web material 30B of the second layer is submerged is 300 μm, and the compressive strain of the region 20b is 40%. Therefore, the web material 30 in the portion where the first-layer web material 30A and the second-layer web material 30B overlap each other receives a compressive stress σ ₃ at 60% compressive strain from the cushioning material 20. On the other hand, the web material 30 having only the second-layer web material 30 </ b> B receives the compressive stress σ ₂ at the compression strain of 40% from the buffer material 20.

Further, as shown in FIG. 4D, when the third layer web material 30 </ b> C is wound on the second layer web material 30 </ b> B, the web material 30 further sinks into the buffer material 20. At this time, if the thickness of the region 20a of the cushioning material 20 in which the overlapped portions of the first to third layer web materials 30A to 30C are sunk is 100 μm, the compressive strain of the region 20a is 80%. On the other hand, the thickness of the region 20b of the cushioning material 20 in which the overlapped portions of the second layer and the third layer web materials 30B and 30C sink is 200 μm, and the compressive strain of the region 20b is 60%. Therefore, the web material 30 in the portion where the first to third layer web materials 30 </ b> A to 30 </ b> C overlap receives the compressive stress σ ₅ at the compression strain of 80% from the buffer material 20. On the other hand, the web material 30 in the portion where the second-layer and third-layer web materials 30 </ b> B and 30 </ b> C overlap each other receives a compressive stress σ ₄ at 60% compressive strain from the buffer material 20.

  FIG. 5 is a graph showing a compressive stress-strain curve of the buffer material 20 in the present embodiment.

As shown in FIG. 5, the cushioning material 20 in the present embodiment has a characteristic that the gradient of the compressive stress-strain curve (change in compressive stress) is small in the range A where the compressive strain is 20% to 80%. Thereby, in the state illustrated in FIG. 4C, the compressive stress σ ₃ (from the cushioning material 20 received by the portion of the web material 30 where the first-layer web material 30A and the second-layer web material 30B overlap with each other). The difference between the compressive stress σ ₂ (compressive strain 40%) that the web material 30 of only the second layer web material 30B receives from the cushioning material 20 is very small. Therefore, at the end of the first layer web material 30A, there is no step due to the difference in compressive stress between the surface of the first layer web material 30A in the region 20a and the surface of the buffer material 20 in the region 20b. . As a result, there is no step mark due to the difference in compressive stress on the surface of the second layer web material 30B at the end of the first layer web material 30A.

Similarly, in the state illustrated in FIG. 4D, the compressive stress σ ₅ (compressive strain 80) that the web material 30 in the portion where the web materials 30 </ b> A to 30 </ b> B of the first to third layers overlap is received from the cushioning material 20. %) And the compressive stress σ ₂ (compressive strain 40%) that the web material 30 of only the second layer and the third layer web material 30B, 30C receives from the cushioning material 20 is very small. Therefore, a step due to a difference in compressive stress does not newly occur on the surface of the second layer and the third layer web members 30B and 30C at the end of the first layer web member 30A.

By the way, when the thickness of the buffer material 20 is t ₁ and the thickness of the web material 30 is t ₂ , the compressive strain of the region 20a of the buffer material 20 in the portion where the web material 30 of the first layer to the n-th layer overlaps, The difference from the compressive strain of the region 20b of the buffer material 20 where the second to n-th layer web materials 30 overlap is always t ₂ / t ₁ × 100 (%). For example, in the example shown in FIGS. 4A to 4D, when the thickness t ₁ of the buffer material 20 is 500 μm and the thickness t ₂ of the web material 30 is 100 μm, the compression strain of the region 20 a of the buffer material 20 The difference from the compressive strain in the region 20b is always 20%.

Therefore, as shown in FIG. 6, the compressive stress when the compressive strain is α% is σ _a, and the compressive stress when the compressive strain is larger than the compressive strain α% by t ₂ / t ₁ × 100 (%) is σ _b . If the difference between σ _a and σ _b is small, the difference in compressive stress (σ _b −σ _a ) that the web material 30 receives is always small during the process of winding the web material 30 around the core 1. Can be maintained. Thereby, the level | step difference trace by a compressive-stress difference can be reduced.

In the present invention, if the ratio of compressive stress (σ _a / σ _b ) is 6 or less (σ _a / σ _b ≦ 6) during the step of winding the web material 30 around the core 1, the step due to the difference in compressive stress. Scratches can be effectively reduced. If σ _a / σ _b exceeds 6, the difference in compressive stress received by the web material 30 becomes large, and it becomes difficult to effectively reduce the level difference marks due to the compressive stress difference. If σa / σ _b ≦ 4, it is possible to more effectively reduce step marks due to the difference in compressive stress.

As described above, when the thickness of the buffer material 20 is t ₁ and the thickness of the web material 30 is t ₂ , the difference between the compressive strain generated in the region 20a and the region 20b of the buffer material 20 is t ₂ / t _1. × 100 (%). Therefore, if the thickness (t ₁ ) of the cushioning material 20 is sufficiently thicker than the thickness (t ₂ ) of the web material 30, that is, if t ₂ / t ₁ × 100 (%) is small, the compressive strain is reduced. Since the difference is small, it is difficult to cause a problem that a step mark due to a compressive stress difference occurs.

Therefore, the step mark due to the difference in compressive stress, which is a problem in the present invention, is that t ₂ / t ₁ ≧ 0.1 when the thickness (t ₁ ) of the buffer material 20 is t _2. Appears when set to. If the thickness (t ₁ ) of the cushioning material 20 is too thin with respect to the thickness (t ₂ ) of the web material 30, the difference in compressive strain generated between the region 20 a and the region 20 b of the cushioning material 20 increases. As a result, it becomes difficult to find the buffer material 20 that satisfies σ _a / σ _b ≦ 6. Therefore, the effect of reducing the step mark due to the compressive stress difference according to the present invention is effective when the thickness (t ₁ ) of the buffer material 20 is set to 0.2 ≧ t ₂ / t ₁ ≧ 0.1. Demonstrated.

  By the way, as shown in FIG. 5, the shock absorbing material 20 in this embodiment is elastically deforming in the range A where the compressive strain is 20% to 80%. Therefore, the cushioning material 20 in contact with the end of the web material 30 is dragged by the sinking of the web material 30 and sinks in the same manner, but the cushioning material 20 in a region slightly away from the end of the web material 30 is Don't sink. As a result, as shown in FIGS. 4B to 4D, the groove 40 remains on the surface of the cushioning material 20 in contact with the end of the web material 30 of the cushioning material 20. If the groove 40 remains, the web material 30 may buckle so as to fill a gap in the groove 40 when a large stress is applied to the web material 30 due to winding.

  However, as shown in FIG. 4E, by winding the web material 30C of the fourth layer on the web material 30C of the third layer and further sinking the web material 30 into the cushioning material 20. The groove 40 can be eliminated for the following reason.

  In the example shown in FIG. 4 (e), the thickness of the region 20a of the cushioning material 20 in which the overlapped portions of the first to fourth layers of the web materials 30A to 30D are 75 μm, and the compressive strain of the region 20a Will be 85%. On the other hand, the thickness of the region 20b of the cushioning material 20 in which the overlapping portions of the second to fourth layer web materials 30B to 30D are sunk is 175 μm, and the compressive strain of the region 20b is 65%.

As shown in FIG. 5, the cushioning material 20 in the present embodiment has a yield point S that indicates plastic deformation at a compressive strain of 85% in the compressive stress-strain curve. The compressive stress at the yield point is σ _s .

  Therefore, in FIG.4 (e), the area | region 20a of the shock absorbing material 20 into which the part which the web materials 30A-30D of the 1st layer-the 4th layer overlapped sank changes from an elastic deformation to a plastic deformation. As a result, the cushioning material 20 that has been dragged by the sinking of the web material 30A and released together with the end of the web material 30A is released from the adhering to the end portion of the web material 30A, thereby remaining in the elastic deformation process. Disappears. Thereby, buckling of the web material 30 resulting from the groove part 40 can be prevented.

Further, the web material 30 in the portion where the first to fourth layer web materials 30 </ b> A to 30 </ b> D overlap is subjected to the compressive stress σ _{s at} the compressive strain of 85%, that is, the compressive stress at the yield point S. The region 20a of the cushioning material 20 in which the overlapped portions of the first to fourth layer web materials 30A to 30D sinks occupies most of the entire circumference of the cushioning material 20, and thus the web material wound around the core 1 30 receives a very large compressive stress σs from almost the entire circumference of the buffer material 20. Thereby, even if it uses a soft material for the buffer material 20, it can prevent that the buffer material 20 deform | transforms by winding of the web material 30, and can also prevent that the web material 30 buckles.

In the present embodiment, the yield point of the cushioning material 20 is preferably generated when the compressive strain is 90% or less. If the yield point occurs when the compressive strain exceeds 90%, an abrupt stress change occurs, which causes local stress to be applied to the web material 30, which may damage the web material 30, which is not preferable. The compressive stress σ _{s at} the yield point S is preferably 10 MPa or more. When the compressive stress σ _{s at the} yield point S is smaller than 10 MPa, it is difficult to prevent the buffer material 20 from being deformed due to the web material 30 being tightened. The compressive stress σ _{s at} the yield point S is preferably 70 MPa or less. If the compressive stress σ _{s at the} yield point S exceeds 70 MPa, the compressive stress σ _s exceeds or approaches the yield strength of the web material 30, which may cause plastic deformation of the web material 30, which is not preferable.

As described above, in the web material winding method of the present invention, the cushioning material 20 formed on the outer peripheral surface of the core body reduces step marks caused by the end step of the conventional web material 30. In addition, a soft foamed resin having a compressive stress of 0.02 MPa or less at a compressive strain of 20% is employed. When the web material 30 is wound around the core provided with the soft cushioning material 20, a step mark due to a newly generated difference in compressive stress is caused by the thickness of the cushioning material 20 (t ₁ ). It becomes apparent when 0.2 ≧ t ₂ / t ₁ ≧ 0.1 for a thickness (t ₂ ) of 30. Then, in the range of the thickness of such a cushioning member 20, as a buffer material 20, compressive stress - in strain curve, the compressive stress and sigma _a of compressive strain α% (20 ≦ α ≦ 60 ), compressive strain (alpha + t ₂ When the compressive stress at / t ₁ × 100)% is σ _b , a material having _a compressive stress ratio (σ _b / σ _a ) of at least 6 or less is used. The step marks due to the difference in compressive stress generated on the surface of the web member 30 can be reduced.

Further, when the thickness (t ₁ ) of the buffer material is set to 0.15 ≧ t ₂ / t ₁ ≧ 0.1 with respect to the thickness (t ₂ ) of the web material to be wound, the compressive stress in the compressive strain α% (20 ≦ α ≦ 65 ) and sigma _a, when the compressive strain was _b compressive stress sigma in _{(α + t 2 / t 1} × 100)%, compression stress ratio (sigma _b / By using a material having a characteristic of σ _a ) of at least 4 or less, step marks due to a difference in compressive stress generated on the surface of the web material 30 can be reduced at the winding end of the web material 30.

  Moreover, the shock absorbing material 20 in this embodiment has the yield point S which shows a plastic deformation at a compressive strain of 90% or less in the compressive stress-strain curve, and the compressive stress at the yield point S is 10 MPa or more. Is preferred.

  By using the cushioning material 20 having such characteristics, it is possible to further reduce the step marks due to the difference in compressive stress, and even if a soft material is used for the cushioning material 20, the seat of the web material 30 generated by the tightening of the web material 30. Bending can be reduced.

  A winding core for winding a web material in another embodiment of the present invention has a winding core body and a cushioning material 20 formed on the outer peripheral surface of the winding core body, and the cushioning material 20 has the following characteristics. .

That is, the buffer material 20 is made of a soft foamed resin having a compressive stress of 20% or less at a compression strain of 0.02 MPa or less, and the thickness (t ₁ ) of the buffer material 20 is when the thickness of the web material 30 to be wound is t _2. 0.2 ≧ t ₂ / t ₁ ≧ 0.1, and the cushioning material 20 has a compressive stress of σ _a when the compressive strain is α% (20 ≦ α ≦ 60) in the compressive stress-strain curve. Σ _b / σ _a ≦ 6, where σ _b is the compressive stress when the compressive strain is (α + t ₂ / t ₁ × 100)%.

  Hereinafter, although the example and the example of the present invention are given and the composition and effect of the present invention are further explained, the present invention is not limited to these examples.

Example 1
A core body made of ABS resin having an inner diameter of 3 inches (outside diameter of about 88 mm) was prepared, and a cushioning material made of polyurethane foam (material A) having open cells was attached to the outer peripheral surface of the core body.

  The buffer material used in this example had a thickness of 750 μm and a compressive stress of 0.020 MPa at a compressive strain of 20%.

  The core body was mounted on a winding device, and a biaxially stretched PET film (with an aluminum vapor deposition film) having a thickness of 75 μm was wound 320 m at a winding tension of 66 N and a winding speed of 150 m / min. The wound PET film was allowed to stand at room temperature for 24 hours, and then a step mark at the winding end of the PET film when unrolled was visually confirmed.

(Comparative Example 1)
A core body made of ABS resin having an inner diameter of 3 inches (outside diameter of about 88 mm) was prepared, and a cushioning material (material B) made of polyethylene foam was attached to the outer peripheral surface of the core body.

  The buffer material used in Comparative Example 1 had a thickness of 750 mm and a compressive stress of 0.35 MPa at a compressive strain of 20%.

  The core body was mounted on a winding device, and a biaxially stretched PET film (with an aluminum vapor deposition film) having a thickness of 75 μm was wound 320 m at a winding tension of 66 N and a winding speed of 150 m / min. The wound PET film was allowed to stand at room temperature for 24 hours, and then a step mark at the winding end of the PET film when unrolled was visually confirmed.

(Comparative Example 2)
A core body made of ABS resin having an inner diameter of 3 inches (outside diameter of about 88 mm) was prepared, and a cushioning material (material C) made of polyurethane foam was attached to the outer peripheral surface of the core body.

  The buffer material used in Comparative Example 2 had a thickness of 750 mm and a compressive stress of 0.012 MPa at a compressive strain of 20%.

  The core body was mounted on a winding device, and a biaxially stretched PET film (with an aluminum vapor deposition film) having a thickness of 75 μm was wound 320 m at a winding tension of 66 N and a winding speed of 150 m / min. The wound PET film was allowed to stand at room temperature for 24 hours, and then a step mark at the winding end of the PET film when unrolled was visually confirmed.

  Table 1 is a table showing the results of evaluating the occurrence of step marks in Example 1, Comparative Example 1, and Comparative Example 2.

  As shown in Table 1, in Example 1, step marks were confirmed up to about 1 m (for four laps), but were not confirmed in further laps. On the other hand, in Comparative Example 1 and Comparative Example 2, step marks were confirmed up to 25 m (about 100 laps) and 10 m (about 40 laps), respectively.

Here, Example 1, Comparative Example 1, Comparative Example 2, the thickness of the buffer material _{(t 1),} the ratio between the thickness of the PET film _{(t 2) (t 2 /} t 1) are all 0.1 It is. Accordingly, Table 1, compressive strain alpha% and (20 ≦ α ≦ 70) in the compression stress (sigma _a), the ratio of compressive strain (α + 10)% in compressive stress _{(σ b) (σ b /} σ a ). For example, in Example 1 of Table 1, the compression stress ratio (σ _b / σ _a ) in the column where the compression strain α is 20% is the compression stress (σ _b = 0.024 MPa) when the compression strain is 30%, It represents the ratio (σ _b / σ _a = 1.2) of compressive stress (σ _a = 0.020 MPa) when the strain is 20%.

As shown in Table 1, in Example 1, when the compressive strain α (%) is in the range of 20 ≦ α ≦ 70, the upper limit value of the compressive stress ratio (σ _b / σ _a ) is 2.7 (α = 70). %)Met. Therefore, the buffer material used in Example 1 always has a small difference (σ _b −σ _a ) in the compressive stress applied to the web material during the process of winding the web material (PET film) around the core. _b / σ _a ≦ 2.7), which is considered to reduce the level difference due to the difference in compressive stress.

In contrast, in Comparative Example 1, although the upper limit value of the compressive stress ratio (σ _b / σ _a ) is as small as 2.2 (α = 70%), the compressive stress at 20% compressive strain of the buffer material Is as large as 0.35 MPa, so when winding the web material around the core body, the end portion of the web material is not enough to sink into the cushioning material, and as a result, the end step of the conventional web material is caused. It is thought that a stepped trace was generated.

In Comparative Example 2, the upper limit value of the compressive stress ratio (σ _b / σ _a ) is 6.8 (α = 70) although the compressive stress at 20% compressive strain of the buffer material is as small as 0.012 MPa. Therefore, it is considered that the generation of step marks due to the difference in compressive stress could not be sufficiently reduced.

(Example 2)
The PET film when unrolled after winding the same PET film (thickness 75 μm) as above in the same manner as in Example 1 except that the thickness of the buffer material (material A) was 550 μm. Step traces at the winding end were visually confirmed.

(Comparative Example 3)
The PET film when unrolled after winding the same PET film (thickness 75 μm) as above in the same manner as in Comparative Example 1 except that the thickness of the buffer material (material B) was 550 μm. Step traces at the winding end were visually confirmed.

(Comparative Example 4)
The PET film when unrolled after winding the same PET film (thickness 75 μm) as above in the same manner as in Comparative Example 2 except that the thickness of the buffer material (material C) was 550 μm. Step traces at the winding end were visually confirmed.

  Table 2 is a table showing the results of evaluating the occurrence of step marks in Example 1, Comparative Example 1, and Comparative Example 2.

  As shown in Table 2, in Example 2, step marks were confirmed up to about 1 m (for four laps), but were not confirmed in further laps. On the other hand, in Comparative Example 3 and Comparative Example 4, step marks were confirmed up to 30 m (about 120 laps) and 20 m (about 80 laps), respectively.

Here, Example 2, Comparative Example 3, Comparative Example 4, the thickness of the buffer material _{(t 1),} the ratio between the thickness of the PET film _{(t 2) (t 2 /} t 1) are all 0.15 It is. Therefore, Table 2, compressive strain alpha% and (20 ≦ α ≦ 65) in the compression stress (sigma _a), the ratio of compressive strain (α + 15)% in compressive stress _{(σ b) (σ b /} σ a ). For example, in Example 2 of Table 2, the compressive stress ratio (σ _b / σ _a ) in the column where the compressive strain α is 20% is the compressive stress (σ _b = 0.028 MPa) when the compressive strain is 35%. It represents the ratio (σ _b / σ _a = 1.4) of compressive stress (σ _a = 0.020 MPa) when the strain is 20%.

As shown in Table 2, in Example 2, when the compressive strain α (%) is in the range of 20 ≦ α ≦ 65, the upper limit value of the compressive stress ratio (σ _b / σ _a ) is 4.2 (α = 65 %)Met. Therefore, the buffer material used in Example 2 always has a small difference (σ _b −σ _a ) in the compressive stress received by the web material during the step of winding the web material (PET film) around the core. _b / σ _a ≦ 4.2), which is considered to reduce the level difference due to the difference in compressive stress.

In contrast, in Comparative Example 3, although the upper limit value of the compressive stress ratio (σ _b / σ _a ) is as small as 3.3 (α = 65%), the compressive stress at 20% compressive strain of the buffer material Is as large as 0.35 MPa, so when winding the web material around the core body, the end portion of the web material is not enough to sink into the cushioning material, and as a result, the end step of the conventional web material is caused. It is thought that a stepped trace was generated.

In Comparative Example 4, the upper limit of the compressive stress ratio (σ _b / σ _a ) is 17.3 (α = 65%) even though the compressive stress at 20% compressive strain of the buffer material is as small as 0.012 MPa. ), It is considered that the generation of step marks due to the difference in compressive stress could not be sufficiently reduced.

(Example 3)
The PET film when unrolled after winding the same PET film (thickness 75 μm) as above in the same manner as in Example 1 except that the thickness of the buffer material (material A) was 370 μm. Step traces at the winding end were visually confirmed.

(Comparative Example 5)
The PET film when unrolled after winding the same PET film (thickness 75 μm) as above in the same manner as in Comparative Example 1 except that the thickness of the buffer material (material B) was 370 μm. Step traces at the winding end were visually confirmed.

(Comparative Example 6)
The PET film when unrolled after winding the same PET film (thickness 75 μm) as above in the same manner as in Comparative Example 2 except that the thickness of the buffer material (material C) was 370 μm. Step traces at the winding end were visually confirmed.

  Table 3 is a table showing the results of evaluating the occurrence of step marks in Example 3, Comparative Example 5, and Comparative Example 6.

  As shown in Table 3, in Example 3, step marks were confirmed up to about 2 m (eight laps), but were not confirmed in further laps. On the other hand, in Comparative Example 5 and Comparative Example 6, step marks were confirmed up to 50 m (about 200 laps) and 20 m (about 80 laps), respectively.

Here, Example 3, Comparative Example 5, Comparative Example 6, the thickness of the buffer material _{(t 1),} the ratio between the thickness of the PET film _{(t 2) (t 2 /} t 1) are all 0.2 It is. Accordingly, Table 3, compressive strain alpha% and (20 ≦ α ≦ 60) in the compression stress (sigma _a), the ratio of compressive strain (α + 20)% in compressive stress _{(σ b) (σ b /} σ a ). For example, in Example 3 of Table 3, the compression stress ratio (σ _b / σ _a ) in the column where the compression strain α is 20% is the compression stress (σ _b = 0.034 MPa) when the compression strain is 40%. It represents the ratio (σ _b / σ _a = 1.7) of compressive stress (σ _a = 0.020 MPa) when the strain is 20%.

As shown in Table 3, in Example 3, when the compressive strain α (%) is in the range of 20 ≦ α ≦ 60, the upper limit value of the compressive stress ratio (σ _b / σ _a ) is 6.1 (α = 60 %)Met. Therefore, the cushioning material used in Example 3 always has a small difference (σ _b −σ _a ) in the compressive stress experienced by the web material during the process of winding the web material (PET film) around the core. _b / σ _a ≦ 6.1), which is considered to reduce the step marks due to the difference in compressive stress.

On the other hand, in Comparative Example 5, although the upper limit value of the compressive stress ratio (σ _b / σ _a ) is as small as 4.1 (α = 60%), the compressive stress at 20% compressive strain of the buffer material Is as large as 0.35 MPa, so when winding the web material around the core body, the end portion of the web material is not enough to sink into the cushioning material, and as a result, the end step of the conventional web material is caused. It is thought that a stepped trace was generated.

In Comparative Example 6, the upper limit value of the compressive stress ratio (σ _b / σ _a ) is 31.7 (α = 60%) even though the compressive stress at 20% compressive strain of the buffer material is as small as 0.012 MPa. ), It is considered that the generation of step marks due to the difference in compressive stress could not be sufficiently reduced.

  From the above results, the cushioning material 20 formed on the outer peripheral surface of the core body has a compressive stress of 0.02 MPa at a compressive strain of 20% in order to reduce the level difference caused by the end step of the conventional web material. It can be seen that it is necessary to use the following soft foam resin.

Then, when winding the web material to the winding core the soft cushioning material is provided, in order to reduce the step difference mark by compressive stress difference newly generated, the thickness of the buffer material a (t _1), wound When 0.2 ≧ t ₂ / t ₁ ≧ 0.1 with respect to the thickness (t ₂ ) of the web material, the compression strain is α% (20 ≦ α ≦ 60) as a characteristic of the buffer material. the compressive stress and sigma _a, when the compressive strain of the compressive stress in the _{(α + t 2 / t 1} × 100)% and the sigma _b, compression stress ratio (σ _b / σ _a), must be at least 6 below It turns out that it is.

From the above results, when the thickness (t ₁ ) of the cushioning material is set to 0.15 ≧ t ₂ / t ₁ ≧ 0.1 with respect to the thickness (t ₂ ) of the web material to be wound, the cushioning as the characteristics of wood, a compressive stress as the sigma _a of compressive strain α% (20 ≦ α ≦ 65 ), when the compressive strain of the compressive stress in the _{(α + t 2 / t 1} × 100)% and the sigma _b, compressive stress By setting the ratio (σ _b / σ _a ) to at least 4 or less, it is possible to reduce step marks due to a difference in compressive stress newly generated when the web material is wound around the core provided with the buffer material. it can.

  Further, in Examples 1 to 3 described above, even when a soft material having a compressive stress of 20% or less at a compressive strain of 0.02 MPa or less is used as the buffer material, the buffer material is deformed by winding the web material. No buckling of the web material was observed. This is because the web material is submerged in the cushioning material until the compressive strain exceeding the yield point indicating the plastic deformation of the cushioning material, and wound on the winding core, so that the web material wound on the winding core is almost the same as the cushioning material. This is thought to be due to a very large compressive stress from the entire circumference. The yield point of the buffer material (material A) used in Examples 1 to 3 was generated with a compressive strain of 85%, and the compressive stress at this yield point was 15 MPa.

  FIG. 7 shows the buffer when the coin is removed after the coin is pressed against the surface of the cushioning material 20 used in the first to third embodiments to sink the cushioning material 20 to a compression strain of 85%. It is the photograph which image | photographed the surface of the material 20. FIG. As shown in FIG. 7, it can be seen that coin-shaped dents due to plastic deformation of the buffer material 20 remain on the surface of the buffer material 20.

  As mentioned above, although this invention was demonstrated by suitable embodiment, such description is not a limitation matter and of course various modifications are possible.

  For example, in the above embodiment, the relationship between the compressive strain of the cushioning material 20 in the winding process of the web material 30 and the compressive stress that the web material 30 receives from the cushioning material 20 using FIGS. However, the number of windings of the web material shown here is only an example for explanation. Of course, the number of windings of the web material and the relationship between the opening and the compression strain and the compressive stress are unambiguous. It is not determined by.

  Moreover, in the said Example, although PET film was demonstrated to the example as the web material 30, it is not limited to this, Of course, this invention is applicable also to another polyester film, a polyethylene film, etc.

1 core 10 core body 20 cushioning material 30 web material 40 groove 50 step

A web material winding method according to the present invention is a winding method for winding a web material around a winding core, and the winding core has a cushioning material formed on the outer peripheral surface of the winding core body. The step of attaching the end of the web material and the step of winding the web material around the core body while applying tension to the web material, and the cushioning material has a compressive stress of 0% at a compressive strain of 20%. 0.02 MPa or less of soft foamed resin, and the thickness (t ₁ ) of the cushioning material is set to 0.2 ≧ t ₂ / t ₁ ≧ 0.1, where t ₂ is the thickness of the web material to be wound. In the compressive stress-strain curve, the buffer material has a compressive stress at a compressive strain of α% (20 ≦ α ≦ 60) as σa and _a compressive stress at _a compressive strain of (α + t ₂ / t ₁ × 100)%. When σ _b is set, σ _b / σ _a ≦ 4, and the web material is the winding core In the step of winding around the body, the compressive strain of the cushioning material when the overlapping portion of the first to nth layer web materials sinks into the cushioning material, and the second to nth layer web materials A difference from the compressive strain of the buffer material when the overlapped portion sinks into the buffer material is t ₂ / t ₁ × 100 (%) .

Claims (5)

A winding method for winding a web material around a core,
The core has a buffer material formed on the outer peripheral surface of the core body,
A step of affixing an end of the web material on the cushioning material;
Winding the web material around the core body while applying tension to the web material,
The buffer material is made of a soft foamed resin having a compressive stress of 0.02 MPa or less at a compressive strain of 20%,
The thickness (t ₁ ) of the cushioning material is set to 0.2 ≧ t ₂ / t ₁ ≧ 0.1, where t ₂ is the thickness of the web material to be wound,
In the compression stress-strain curve, the buffer material has a compressive stress of σ _a when the compressive strain is α% (20 ≦ α ≦ 60), and the compressive stress when the compressive strain is (α + t ₂ / t ₁ × 100)%. _A web material winding method in which σ _b / σ _a ≦ 6 when _b . The thickness (t ₁ ) of the cushioning material is set to 0.15 ≧ t ₂ / t ₁ ≧ 0.1, where t ₂ is the thickness of the web material to be wound,
In the compressive stress-strain curve, the buffer material has a compressive stress of σ _a when the compressive strain is α% (20 ≦ α ≦ 65), and the compressive stress when the compressive strain is (α + t ₂ / t ₁ × 100)%. when it is _b, a σ _{b /} σ _a ≦ 4, winding method of a web material according to claim 1.   In the step of winding the web material around the core body, the web material is sunk into the buffer material until the compression strain exceeds the yield point indicating the plastic deformation of the buffer material, and is wound around the core body. The web material winding method according to claim 1 or 2. A winding core for winding web material,
A core body,
Having a cushioning material formed on the outer peripheral surface of the core body,
The buffer material is made of a soft foamed resin having a compressive stress of 0.02 MPa or less at a compressive strain of 20%,
The thickness (t ₁ ) of the cushioning material is set to 0.2 ≧ t ₂ / t ₁ ≧ 0.1, where t ₂ is the thickness of the web material to be wound,
In the compression stress-strain curve, the buffer material has a compressive stress of σ _a when the compressive strain is α% (20 ≦ α ≦ 60), and the compressive stress when the compressive strain is (α + t ₂ / t ₁ × 100)%. _A winding core where σ _b / σ _a ≦ 6 when _b . The thickness (t ₁ ) of the cushioning material is set to 0.15 ≧ t ₂ / t ₁ ≧ 0.1, where t ₂ is the thickness of the web material to be wound,
In the compressive stress-strain curve, the buffer material has a compressive stress of σ _a when the compressive strain is α% (20 ≦ α ≦ 65), and the compressive stress when the compressive strain is (α + t ₂ / t ₁ × 100)%. _The core according to claim 4, wherein σ _b / σ _a ≦ 4 when _b .