JP2013075751A - Winding body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good-looking winding body for winding up a film having a super smooth surface in which a pimple fault caused by a step of a start of winding is suppressed, and wrinkles are also suppressed.SOLUTION: The winding body includes: a core body 1; a winding-up core having a coating layer 2 formed on a surface of the core body; and the film 4 wound around the winding-up core. The surface hardness of the coating layer is not lower than 45 degrees and lower than 60 degrees, and a centerline average surface roughness Ra of the film is equal to or lower than 20 nm.

Description

  The present invention relates to a winding body having a film wound around a winding core having a core body and a coating layer provided on the surface of the core body. More specifically, the present invention relates to a wound body in which defects and wrinkles due to steps such as film edges at the beginning of winding are suppressed.

  A paper tube, a metal tube, an FRP tube, or the like is used as a core used for winding the film. To wind a film around the core, the film tip is placed on the surface of the core, for example, using a double-sided tape. A method of adhering and fixing, or a method of winding and fixing the film tip region around the outer periphery of the core by a plurality of times is adopted. By the way, when the film is wound around the core by these methods, step marks such as wrinkles and creases caused by steps corresponding to the thickness of the film edge and the double-sided tape are generated in the film winding start region. In particular, when the film is wound, in order to prevent bamboo shoots (the film from shifting in a conical shape in the width direction of the wound film) to prevent the film from becoming conical, step marks are noticeably generated. . If the wound film is used for applications that do not allow slight defects such as optical films, such as anti-reflection films for displays, anti-glare films, and electromagnetic wave cut films, This area is inevitably removed as a defective product, which causes a decrease in product yield.

Then, in order to prevent a trace of a step from remaining in the film at the beginning of winding, a winding core (Patent Document 1) in which a foamed resin sheet is wound around the outer peripheral surface, and the outer peripheral surface has a compressive stress of 0.01 to 0.1 kgf / cm ² . There have been proposed a winding core (Patent Document 2) covered with a foamed resin cushion material, and a winding core (Patent Document 3) whose outer peripheral surface is covered with rubber having a rubber hardness of 60 to 75 degrees.
However, with a winding core in which a foamed resin-based sheet or cushion material is wound around the outer peripheral surface, when the film tip is fixed and wound around the surface of the foam constituting the coating layer, The foam itself pressed by the film is distorted and wrinkles are generated. The wrinkle moves as the film is wound, so that when the film is wound once, the wrinkle of the foam is pressed to the position where the film tip is fixed. There was a problem that the film remained in the position and transferred to a film wound on the film, resulting in a defect. In addition, since a foamed resin-based sheet or cushion material is wound around the outer peripheral surface of the core, there is a problem that a joint is generated and a step mark of the joint remains on the film. On the other hand, the winding core coated with hard rubber as in Patent Document 3 has a problem in that it cannot absorb the step corresponding to the thickness of the film edge or the double-sided tape, and a step mark remains in a considerable length portion.

In order to solve these problems, a technique has been reported in which a core layer is provided with a coating layer, and the coating layer is formed of a gel having a Young's modulus of 1 kPa to 2,000 kPa (Patent Document 4).
By the way, as for an optical film used as a support for a touch panel or the like, for example, a film having a thickness of about 50 to 250 μm is generally used in order to obtain necessary strength, but excellent transparency is required. Therefore, in many cases, the film having an ultra-smooth surface is usually used with the ultra-smooth surface without minimizing the internal additive particles or using any additive particles. As reported in Fig. 4, in the technology using a very soft coating layer, wrinkles may occur due to slight tension variations during winding, and the effect of suppressing wrinkles is still insufficient. Newly found that the request cannot be met. Moreover, in these prior arts, the pimple-like defect (protruding bulge) caused by the step at the beginning of winding has not been completely solved.

JP-A-5-53249 Japanese Patent Laid-Open No. 9-142739 No. 7-39912 JP 2005-96927 A

  The present invention is a wound body in which a film having an ultra-smooth surface is wound, and pimple-like defects (protruding bulges) caused by a step at the beginning of winding are suppressed, and at the same time, wrinkles are suppressed, Is intended to provide a good wound body.

The present invention employs the following configuration in order to solve the above problems.
(1) A winding core having a winding core body and a coating layer provided on the surface of the winding core body, and a film wound around the winding core, the surface hardness of the coating layer being 45 degrees As mentioned above, the winding body which is less than 60 degree | times and whose centerline average surface roughness Ra of this film is 20 nm or less.
(2) The wound body according to (1), wherein the coating layer has a step, and the step height is 25 to 300 μm.
(3) The winding body according to (1) or (2), wherein the coating layer is made of synthetic polymer rubber, and the thickness of the coating layer is 0.5 to 5 mm.
(4) The wound body according to any one of (1) to (3), wherein the film is a polyester film containing substantially no particles.

  According to the present invention, it is a wound body in which a film having an ultra-smooth surface is wound, and the pimple-like defects caused by the step at the beginning of winding are suppressed, and at the same time, wrinkles are suppressed, and the wound appearance is good. Can be provided.

(A) is a schematic perspective view which shows the winding core which concerns on embodiment of this invention, (b) is the schematic sectional drawing, (c) is a schematic sectional drawing of the winding body by which the film was wound around the winding core. It is.

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1A is a schematic perspective view showing a winding core according to a preferred embodiment of the present invention, and FIG. 1B is a schematic cross-sectional view thereof. FIG.1 (c) is a schematic sectional drawing of the winding body by which the film was wound around the winding core. The winding core includes a core body 1 and a coating layer 2 formed on the outer periphery of the core body 1 at least in a film winding region for winding the film 4. The core body 1 can be made of any material as long as it has the strength and rigidity necessary for winding and holding the film 4, and specifically, a resin tube such as an FRP tube or ABS, or a metal tube. Paper tubes, etc. are used. The covering layer 2 is provided to absorb a step caused by a film end of a film wound around a winding core or a step caused by a double-sided tape for film adhesion, and is formed of an elastic body having a surface hardness of 45 degrees or more and less than 60 degrees. Yes.
Furthermore, in order to further enhance the effect of absorbing the step on the film cut surface, it is more preferable to provide the coating layer 2 with a step 3 that matches the shape of the film cut surface.
Hereafter, each component which comprises the winding body of this invention is demonstrated in detail.

<Winding core>
The winding core in the present invention is obtained by providing a coating layer 2 having a specific hardness on the surface of the core body 1 described above.

[Coating layer]
(surface hardness)
The coating layer 2 in the present invention has a surface hardness of 45 degrees or more and less than 60 degrees. When the surface hardness of the coating layer 2 is in the above numerical range, the wound shape is excellent. Moreover, for example, a highly smooth film that can be used as an optical film has a problem that due to the influence of gravity or the like, winding deviation occurs inside the roll over time, and fine scratches are generated on the film surface. This problem can be suppressed. The smaller the surface hardness, the greater the effect of absorbing the step due to the film edge and the step due to the double-sided tape for film adhesion, but if it is too low, the core tends to wrinkle. Moreover, it exists in the tendency for a film surface crack to generate | occur | produce easily as mentioned above. Furthermore, there is a problem that it is difficult to obtain an elastic body, the coating layer 2 is easily peeled off or damaged, and handling becomes difficult. From this viewpoint, the surface hardness of the coating layer 2 is preferably 48 degrees or more. On the other hand, if the surface hardness is too high, a step defect due to the film end tends to occur, and a pimple-like defect due to this tends to occur. From this viewpoint, the surface hardness of the coating layer 2 is preferably 56 degrees or less, more preferably 52 degrees or less.
In order to obtain such surface hardness, the material and thickness of the coating layer may be appropriately adjusted.

(Material)
The elastic body used for the coating layer 2 in the present invention is not particularly limited as long as it satisfies the numerical range of the surface hardness, but synthetic polymer rubber is preferable from the viewpoint of easy procurement and easy processing. . Examples of such synthetic polymer rubber include styrene butadiene rubber, acrylonitrile butadiene rubber (NBR), chloroprene rubber, butyl rubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber, silicone rubber, fluorine rubber, urethane rubber, among others. Acrylic nitrile butadiene rubber is advantageous in terms of cost and is preferable. Moreover, it is also preferable to use an adhesive (adhesive synthetic polymer rubber), for example, butyl rubber, as the elastic body for forming the coating layer, whereby the occurrence of pimple-like defects can be suppressed to a higher degree. . Moreover, when winding a film around the outer peripheral surface of a coating layer, it becomes possible to wind without fixing the film front-end | tip with a double-sided tape, and the film 4 winding operation | work with respect to a core can be simplified.

(Thickness)
When the thickness of the coating layer 2 is reduced, the step absorption effect is reduced. On the other hand, when the thickness is increased, the cost is increased and the surface is easily damaged. Therefore, the thickness is preferably selected to be about 0.5 to 5 mm, and more preferably about 1 to 3 mm. More preferably, it is selected.

(Step)
The covering layer 2 in the present invention is preferably provided with a step 3 as shown in FIG. The step 3 is provided in order to match the shape of the film cut surface, and the height thereof is appropriately equivalent to the thickness of the film to be wound, preferably about 25 to 300 μm, more preferably about 50 to 250 μm.

<Winding body>
In the wound body of the present invention, as shown in FIG. 1B, a film 4 is wound around a winding core having a core body 1 and a coating layer 2 provided on the surface of the core body. It is what was done.

[the film]
(Surface roughness)
The center line average surface roughness Ra of the film 4 in the present invention is 20 nm or less. Here, the center line average surface roughness is a value measured according to JIS B 0601-2001, as will be described later. When a film having such a center line average surface roughness in the above numerical range is wound around the above-described winding core to create a wound body, a wound body having an excellent winding shape is obtained. When the surface roughness is too large, it tends to cause winding deviation. From such a viewpoint, the surface roughness is preferably 15 nm or less.
In order to achieve such surface roughness, the particles and film thickness added to the film, the particles and coating layer thickness added to the coating layer that may be provided on the film, and the film forming conditions (stretch ratio, stretching temperature, heat setting) Temperature) and the like may be adjusted as appropriate.

(Material)
The film 4 in the present invention is not particularly limited as a resin constituting the film. However, when used for optical applications, for example, from the viewpoint of mechanical properties, heat resistance, handling properties, and the like, a cycloolefin resin film and a polycarbonate resin. A film, a polyester film, etc. are mentioned, A polyester film is preferable from the surface of versatility.

In the present invention, the polyester constituting the polyester film is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Examples of the polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene-2,6-naphthalate. The polyester may be a copolymer of these copolymers or a blend thereof with a small proportion of other resins. Among these polyesters, polyethylene terephthalate and polyethylene-2,6-naphthalate are particularly preferable because of a good balance between mechanical properties and optical properties.
Polyester films are highly rigid and are likely to wrinkle. Therefore, using the wound body of the present invention is effective in suppressing the wrinkle problem.

(particle)
The film in the present invention may contain appropriate particles as necessary, but from the viewpoint of improving transparency, it is better that the number of particles in the film is small, and substantially no particles are contained (film) 10 ppm or less, preferably 5 ppm or less). When using particles, as the particles, those conventionally known as a slipperiness imparting agent for polyester films can be used. Examples include calcium carbonate, calcium oxide, aluminum oxide, kaolin, silicon oxide, zinc oxide, carbon black, silicon carbide, tin oxide, crosslinked acrylic resin particles, crosslinked polystyrene resin particles, melamine resin particles, and crosslinked silicone resin particles. it can.

(Thickness)
The thickness of the film in the present invention is preferably 25 to 300 μm, particularly 50 to 250 μm, in order to obtain strength required when used as a support for optical films such as hard coats, touch panels, and antiglare treatments. It is preferable that

(Coating layer)
In the present invention, for the purpose of improving the slipperiness, adhesion and the like of the film, it is preferable to have a coating layer made of a polymer resin and fine particles on one side or both sides. In addition, what is necessary is just to adjust the aspect of the microparticles | fine-particles in this coating layer so that the surface roughness of a film may become the range mentioned above.

<Method for manufacturing winding core>
In the present invention, the method for forming the winding core by providing the core body 1 with the coating layer 2 is not particularly limited, and examples thereof include the following methods.
The winding core is manufactured using a molded product obtained by extruding an unvulcanized rubber containing a vulcanizing agent or a crosslinking agent on the outer periphery of a core rod (core body) using an extruder, or a calender roll machine. It can be performed by a method in which a molded product obtained by winding a sheet-like unvulcanized rubber around the outer periphery of the core rod is heated and vulcanized or crosslinked.

<Manufacturing method of winding body>
The winding body in the present invention uses the winding core obtained as described above, and a continuous winding device (one piece) included in a film forming step of forming a biaxially stretched film by stretching a sheet-like film. This is a winding body in which a film is wound by a continuous winding device having two winding reels A and B and capable of continuous winding by alternately performing a switching operation. Further, in the film forming process, the wound film may be wound by a winding device in a slitter process in which the film once wound is wound back and subjected to slit, secondary processing or the like to a required size.
For example, in a continuous winding device, when a film wound around a winding core on the winding reeler side (assumed to be a reeler A) that has already started winding reaches a predetermined length, the film cutting device moves in the width direction. Acts laterally and winding is complete. At the same time, the film is wound on a reel B side winding core (generally, a double-sided adhesive tape for film adhesion is generally affixed to the winding core in advance) matched to the film conveyance speed, and wound. The take-up reeler switching operation is completed. After the switching operation, the winding core is switched from speed control to tension control, and a predetermined winding appearance can be obtained.
In order to wrap a film around a winding core, it is common to use a double-sided tape for film adhesion. In addition to a step due to a film edge, a step due to a double-sided tape can also cause a pimple-like defect. Therefore, it is also effective to use an adhesive material such as butyl rubber for the coating layer.

Hereinafter, the present invention will be described more specifically with reference to examples. The measurement items in the following examples were measured as follows.
(1) Surface Hardness Using a JIS spring type (durometer) hardness tester type A, the instrument was pressed lightly against the pressure surface against the rubber surface, and the hardness was measured (JIS K6253).
(2) Surface roughness of film Using a two-dimensional surface roughness measuring device (manufacturer: Kosaka Laboratory, type: Surfcorder SE-30D), centerline average surface roughness Ra was determined (JIS B 0601-2001). .
(3) Pimple-like defects As a method for determining pimple-like defects (protruding protrusions), the presence or absence of pimple-like defects was determined by visual observation during winding.
○: No pimple-like defect ×: There is a pimple-like defect.
(4) Wrinkle As a method for determining wrinkles, the presence or absence of wrinkles was visually determined on a film roll being wound.
○: No wrinkles ×: Wrinkles (5) Time-lapse surface scratches A method for determining time-lapse surface scratches was a product roll that had passed 48 hours after winding in an environment of 23 ° C. and 50% RH immediately after winding. Using Ayaha Engineering's iris + (light source LED), scratch-shaped defects detected in the transmission mode are counted for 0.5 mm or more, converted into the number per square meter, and Asked.
Number of surface scratches over time = (number of defects in time roll)-(number of defects immediately after winding)
○: Number of surface scratches with time is less than 5.0 / m ² ×: Number of surface scratches with time is 5.0 / m ² or more

[Examples 1-2, Comparative Examples 1-3]
Hereinafter, examples in which the winding core of the present invention is actually applied to a winding core for a winder of a film forming apparatus will be described. A winding core having the structure shown in FIG. 1 was applied to a winding core for a winder of a biaxially stretched polyester film production facility.
Here, the material of the core body, the material of the coating layer, the hardness, the thickness, the level difference of the coating layer, the material of the film, the center line average surface roughness, the presence or absence of particles, the thickness, etc. are as shown in Table 1. .
The winding conditions are as follows.
Film width: 2.5m
Winding length: 200m
Winding speed: 25 m / min Tension: 50 kg / m (constant)
Table 1 shows the results of visual observation of the pimple-like defects from the winding core, the presence or absence of wrinkles, and surface scratches. As shown in Table 1, according to the present invention, a roll-up body is obtained by winding a film having an ultra-smooth surface. There was no winding, and the winding body with the favorable winding appearance was able to be obtained.

(* 1) NBR: Acrylonitrile butadiene rubber (* 2) PET: Polyethylene terephthalate (* 3) The coating layer of the film is 90% by weight of polyester resin on both sides of the film, 5% by weight of silica particles with an average particle size of 40 nm, nonionic A coating layer composed of 5% by weight of a surfactant is provided with a thickness (dry) of 0.06 μm.

  The wound body in which the film such as the polyester film of the present invention is wound can largely suppress defects that are likely to occur in the innermost layer film and can improve the product yield. Since the cost can be reduced, it is useful for optical films such as anti-reflection films for displays, anti-glare films, electromagnetic wave cut films, conductive film substrates, etc. is there.

1: Core body 2: Cover layer 3: Step 4: Film

Claims (4)

  A winding core having a winding core body and a coating layer provided on the surface of the winding core body; and a film wound around the winding core, the surface hardness of the coating layer being 45 degrees or more, 60 A wound body having a center line average surface roughness Ra of 20 nm or less.   The wound body according to claim 1, wherein the coating layer has a step, and the step height is 25 to 300 μm.   The wound body according to claim 1 or 2, wherein the coating layer is made of a synthetic polymer rubber, and the thickness of the coating layer is 0.5 to 5 mm.   The wound body according to any one of claims 1 to 3, wherein the film is a polyester film containing substantially no particles.