JP2002211803A - Film roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film roll capable of preventing the occurrence of a black belt and depression during storage. SOLUTION: This film roll is constituted such that knurling is applied to a side end part to wind a film 1 around a winding core 2, a difference in thickness in the direction of width of the film 1 is 5 μm or less except in a knurling part, and a thickness of the knurling is 3 to 15 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film roll provided with knurling (fine irregularities, also referred to as embossing, knurling, etc.) on a side edge of a film web and wound around a core. It is about.

[0002]

2. Description of the Related Art In winding a web, it is known that a web is given a certain thickness of knurling to prevent a winding shift and a loosening. For example, Japanese Patent Application Laid-Open No. 4-85248 discloses an apparatus for winding a continuous web having embossed portions on both sides in the width direction while pressing a touch roll toward a core. JP-A-8-2441
No. 13 discloses an apparatus for performing knurling on both ends of a web. Japanese Patent Publication No. 19452/1993 discloses that the preferable thickness of the knurling is preferably 5% or more and 50% or less of the web thickness. Japanese Patent Application Laid-Open No. 8-262621 discloses a method of imparting knurling downstream of a touch roll. Japanese Patent Application Laid-Open No. 9-319029 discloses that the height of the emboss is 5 to 40 μm. Japanese Patent Application Laid-Open No. H8-244035 discloses that knurling is pre-empted. Japanese Patent Application Laid-Open No. 11-262950 discloses that the shape of the teeth of a knurl roller is pyramidal.

By the way, a thin film, for example, having a thickness of 2
When a film having a thickness of 5 to 100 μm is wound into a roll and stored, a thick unevenness called a black band is generated on the center of the core. When the film is required to have strict quality such as optical use, the change in the optical properties of the film due to the black band also becomes a problem. In order to prevent the occurrence of the black band, as shown in FIG. 5, there is a method of increasing the thickness of the film in the width direction at both ends and reducing the thickness at the center.

[0004]

However, when the film roll is stored, there is a problem that a depression is formed on the upper portion with the passage of time. A typical example of the depression 3 occurs on both sides of the top of the roll placed horizontally as shown in FIG. 3 or on the top and possibly both sides as shown in FIG.

[0005] It is an object of the present invention to provide a film roll which, during storage, is free of depressions in addition to black bands.

[0006]

Means for Solving the Problems The present inventor has conducted intensive studies in order to solve the above-mentioned problems, and has first confirmed that deformation due to the depression is also a problem as an optical film or the like. In pursuit of the cause of this collapse, the reason for the collapse in the winding form is that the film has a low buckling strength with respect to the curvature of the winding diameter, so that a pattern with a large thickness difference that forms a bottom shape in the width direction and It has been found that when the knurling is thick, the air layer at the center in the width direction is crushed, resulting in the formation of a depression. Therefore, the bottom of the ship in the width direction thick pattern at the time of film formation is reduced. Specifically, the thickness difference in the width direction is 5 μm or less, and the knurling thickness is 3 to 1
By controlling it to 0 μm, it prevents collapse even after storage,
A good film roll without black belt was successfully obtained.

The present invention has been made based on these findings, and is a film roll in which a knurling is provided on a side end and a film is wound around a core, and the film roll in the width direction of the film is provided. 5μ thickness difference except for knurling
m or less, and the thickness of the knurling is 3 to 15 μm.
And a film roll.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The material of the film to which the present invention is applied is not limited. Examples thereof include cellulose acetate such as cellulose triacetate, and plastic films such as polyester such as polyethylene terephthalate and polyethylene naphthalate. This film to be a bulk roll has a width of about 600 to 3500 mm, usually about 1000 to 1600 mm, and a thickness of 25 to 10 on average.
About 0 μm, preferably about 25 to 55 μm, and
Winding length is about 500-10000m, usually 2000-6
It is about 000 m.

In the present invention, the thickness difference in the width direction of the film, that is, the thickness difference between the maximum thickness portion and the minimum thickness portion excluding the knurling portion is 5 μm or less, preferably 1 to 5 μm.
m, particularly preferably 1 to 4 μm. This thickness difference is usually provided by making the central part thinner and the side edges thicker.

Although the shape of the knurling applied to the film is not particularly limited, it is, for example, an aggregate such as a truncated pyramid, a truncated cone, a hill, a waveform, a lattice, and an irregular shape. Each of the above shapes may be either a protrusion or a depression, and the knurling may be formed on one side of the web as shown in FIG. 6A or on both sides as shown in FIG. . The diameter of each protrusion or recess is about 50 to 1000 μm,
Usually, it is about 100 to 300 μm. The density is about 20 to 1000 pieces / cm ² , usually 50 to 200 pieces / cm ^2.
cm ² . The thickness of the knurling (the average value when there is a difference in height and variation) is AB in FIG.
This knurling thickness is about 3 to 15 μm in the present invention,
Preferably it is about 3 to 10 μm.

The ratio of the knurling thickness (AB) to the film thickness (B) is (AB) /B=0.05 to 0.2.
It is about 25, preferably about 0.05 to 0.15.

The width of the knurling applied to the film is 1
It is about 0.2 to 1.5% of the film width per book (one side), usually about 0.4 to 1.0%. The inner edge of the knurling is preferably within 30 mm, particularly within 15 mm from the edge of the film.

The outer diameter of the core is about 50 to 500 mm, usually about 100 to 300 mm.

The outer diameter of the film roll is from 250 to 1500
mm, usually about 400 to 1000 mm.

According to the present invention, a polymer solution film cast from a die is solidified while being transported while being supported by a belt-type or drum-type support, and is peeled off from the support and dried. It is effective for a film produced by a so-called solution casting method, and is particularly effective for a thin film of cellulose triacetate.

The film roll of the present invention requires extremely uniform optical characteristics and can be used as a protective film for a polarizing plate for precisely coating a functional film such as an antireflection layer.

The polarizing plate is composed of a stretched PVA film and a protective film sandwiching the film, and its performance is greatly affected by the flatness, optical characteristics and mechanical properties of the protective film. Generally, a protective film is required to have a smooth appearance, a uniform thickness, optical properties with small anisotropy, appropriate strength and flexibility, and physical properties with small dimensional changes.

[0018]

EXAMPLE 1 Film thickness of 40 μm or 80 μm and width of 1336 m
10 mm wide knurling at both ends of the cellulose triacetate film having a distance of 11 to 1 between the inner edge and the ear edge.
It was provided to be 5 mm. The initial winding tension of this film was 30 kg under the conditions shown in Table 1, and the winding end was 20 k.
The film was wound around a plastic core having a core diameter of 16.9 cm with a take-up length of 2600 m to obtain a film roll.

FIG. 1 shows the shape of the film roll.
In the figure, 1 is a film, and 2 is a winding core. Reference numeral 3 denotes a depression, and reference numeral 4 denotes a black belt.

Each film roll was stored for one month, and the state was measured. The results are shown in Table 1.

[0021]

[Table 1]

The depth D of the depression 3 is, as shown in FIG.
The thread 5 was stretched at both ends of the center of the depression 3 and the depth of the deepest portion was measured and found. The black belt portion 4 is seen through the portion, and the other portion looks black from the light reflecting portion. Further, the vertical diameter difference are those the difference _C 2 -C ₁ was determined by measuring the _{C 1} and _{C 2} in FIG. 1. The flatness of the polarizing plate is evaluated by sticking a protective film to the polarizing film, cutting out the polarizing film, and then reflecting the appearance by reflecting light.

[0023]

According to the present invention, it is possible to take up a roll having a good winding appearance with less collapse and no black belt even after storage. The film roll obtained by the present invention is 1
Depression within 15mm within 10 months, 10mm difference in vertical diameter
Within.

[Brief description of the drawings]

FIG. 1 is a perspective view of a film roll in which depressions and black bands have occurred.

FIG. 2 is a partial cross-sectional view illustrating a method for measuring the depth of depression.

FIG. 3 is a cross-sectional view of the film roll in a direction perpendicular to the axial direction, showing a depressed position.

FIG. 4 is a cross-sectional view of the film roll in a direction perpendicular to the axial direction showing a depressed position.

FIG. 5 is a cross-sectional view in the film width direction exaggerating a change in thickness.

FIG. 6 is a cross-sectional view of a film side end showing a knurling portion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Film 2 ... Core 3 ... Depressed part 4 ... Black belt part 5 ... Thread

Claims (2)

[Claims] 1. A film roll in which a film is wound around a core with knurling applied to a side end portion, wherein the difference in thickness in the width direction of the film is 5 μm excluding the knurling portion.
m or less, and the thickness of the knurling is 3 to 15 μm.
Film roll, characterized in that 2. The film roll according to claim 1, wherein the film has a thickness of 25 to 100 μm and is used as a protective film for a polarizing plate.