JPH0957872A - Film roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow wrinkle to scarcely occur near a winding core by forming a film to have a specific thickness and permitting the thermal expansion coefficients of the core and the film to satisfy a specific formula. SOLUTION: The film thickness is 20μm or less, and the thermal expansion coefficients of a winding core and the film satisfy a formula |αTF-αTC| <=15.0×10<-6> , where αTF is the thermal expansion coefficient (/ deg.C)<1> of the film, and αTC is the thermal expansion coefficient (/ deg.C) of the core. The base material of the core is formed particularly of fiber-reinforced plastic with a light weight and effective at the point of handling. Particularly, polyester resin having a main structural unit of at least one type selected from ethylene terephthalate. ethylene α,β-bis(2-chromium phenoxy)ethane-4,4'-dicarboxylate, ethylene 2,6- naphthalate unit. has remarkable wrinkle preventing curing. The method for winding the film is preferably a surface winding type capable of controlling a contact pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film roll formed by winding a thin film. Specifically, in a film roll made of a film having a film thickness of 20 μm or less, by reducing the absolute value of the difference in the coefficient of thermal expansion between the winding core and the film, the film is generated near the winding core due to temperature change. The present invention relates to a film roll capable of preventing wrinkles.

[0002]

2. Description of the Related Art When the film thickness exceeds 20 .mu.m, the air layer entrapped between the film layers during film winding is large, so that the deformation due to the thermal expansion or contraction of the film is absorbed in this air layer and the film near the winding core is absorbed. The "wrinkles" that occur on the skin are unlikely to occur. However, if the film thickness is 20 μm or less, “wrinkles” that occur over time are likely to occur. In order to prevent the occurrence of such "wrinkles",
It is known to reduce the air layer caught between the film layers during film winding (see, for example, JP-A-57-57).
193322). However, if the air layer is small, the deformation due to the thermal expansion or contraction of the film due to the temperature change cannot be completely absorbed in the air layer, and especially in the vicinity of the winding core, if the distortion amount due to the deformation becomes large, "wrinkles" are generated. .

It is also known to form regular irregularities on the winding core in order to prevent the irregularities of the winding core from being transferred to the film surface (for example, JP-A-62-2).
No. 22976). However, no change in temperature of the winding core has been suggested, and the occurrence of "wrinkles" as described above cannot be avoided.

[0004]

The above-mentioned conventional film rolls are intended to prevent wrinkles that occur over time. However, during the distribution process of the film, the film is in roll form and is placed under various environments. When the temperature changes, the film expands or contracts, and if the amount of deformation exceeds the amount that can be absorbed by the air layer interposed between the film and film layers, the amount of distortion increases and "wrinkles" near the winding core.
Cause the occurrence of. For this reason, the film roll may not be usable in the film processing in the subsequent process. For example, when a wrinkled film roll is used as a base film for a magnetic recording medium in which the flatness of the film is strictly required, coating unevenness of the magnetic layer is caused in the magnetic tape manufacturing process, and the yield is remarkably reduced. Also,
When used as a film for capacitors, there were various problems such as surface defects in the wrinkles, which markedly deteriorated the electrical characteristics.

As a method for preventing such "wrinkles", various resin films have been proposed which seek thermal stability of the film, but they have not been solved yet.

An object of the present invention is to solve the above problems and to provide a film roll which is less likely to cause "wrinkles" near the winding core.

[0007]

The above-mentioned objects of the present invention are as follows.
In a film roll having a film and a winding core, a film roll having a film thickness of 20 μm or less, and a thermal expansion coefficient of the winding core and the film satisfying the following formula (1) is achieved.

| Α _TF −α _TC | ≦ 15.0 × 10 ⁻⁶ (1) α _TF : thermal expansion coefficient of film (/ ° C.) α _TC : thermal expansion coefficient of winding core (/ ° C.)

A film roll satisfying the following formula (2) is preferable.

| Α _TF −α _TC | ≦ 8.0 × 10 ⁻⁶ (2) α _TF : thermal expansion coefficient of film (/ ° C.) α _TC : thermal expansion coefficient of winding core (/ ° C.)

The coefficient of thermal expansion of the film can be achieved at a desired value by appropriately adjusting the draw ratio, the drawing temperature, the heat treatment temperature, the heat treatment time, etc. in the film manufacturing process, and the coefficient of thermal expansion of the winding core is obtained. A desired value can be achieved by appropriately adjusting the molding temperature, the molding time, the annealing temperature, the annealing time and the like in the process.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The film of the present invention has a three-dimensional surface roughness (SRa) of 0.02 on at least one side.
It is preferably not more than 0.1 μm, more preferably 0.1 μm or less.
It is not more than 01 μm. If the amount exceeds this range, the unevenness of the film surface becomes large, and the electromagnetic conversion characteristics may be remarkably deteriorated as a base film for a magnetic recording medium which requires a strict flatness of the film.

The surface roughness (Ra) of the winding core according to the present invention is preferably 0.5 μm or less, more preferably 0.2 μm or less. If the thickness exceeds the above range, the irregularities on the surface of the winding core are transferred to the surface of the film to be wound, so that as a base film for a magnetic recording medium in which the flatness of the film is strictly required, the electromagnetic conversion characteristics are significantly deteriorated. It may happen. The method for setting the surface roughness (Ra) of the winding core in such a range is as follows.
Although not particularly limited, a desired surface roughness can be obtained by using a hard resin such as an epoxy resin for the core surface and precisely grinding the surface. In particular, if a buffing process is performed after grinding, more accurate finishing can be achieved. Further, it is preferable that the three-dimensional surface roughness (SRa) of at least one surface of the film is smaller than the surface roughness (Ra) of the winding core. When the surface roughness of the take-up core is equal to or less than the surface roughness of the film, air is accumulated when the film is attached to the take-up core, and “wrinkles” may occur if the film is wound as it is. is there.

The elastic modulus (Ya) in the axial direction of the winding core is preferably 1000 kg / mm ² or more, more preferably 1500 kg / mm ² or more. If a take-up core that is less than this range is used, the take-up core may be deformed due to the tension and contact pressure applied when the film is taken up. The circumferential elastic modulus (Yr) of the winding core is also 100.
It is preferably 0 kg / mm ² or more, and more preferably 1500 kg / mm ² or more. If a winding core less than this range is used, the winding core may be deformed as described above. The method for adjusting the strength of the winding core to such a range is not particularly limited, but for example, in the case of a fiber reinforced plastic core, it can be adjusted by appropriately selecting the amount of carbon fiber yarn in the base material, and the base material The desired strength can also be obtained by adjusting the thickness of the.

The base material of the winding core in the present invention is not particularly limited, but it is desirable to use a material having high strength such as fiber reinforced plastic, aluminum or iron. In particular, the core made of fiber reinforced plastic is lightweight and is effective in handling.

The resin in the present invention is not particularly limited, and specific examples thereof include polyester resin, polyamide resin, polyolefin resin, polyphenylene sulfide resin, and the like.
Ethylene terephthalate, ethylene α, β-bis (2-
Chlorphenoxy) ethane-4,4'-dicarboxylate, ethylene 2,6-naphthalate units in the case of a polyester resin having at least one main structural unit as a main structural unit, to prevent "wrinkle" in the film roll of the present invention. It is desirable because the effect becomes remarkable. It should be noted that two or more kinds of resins may be mixed for the purpose of increasing the strength or a copolymerization polymer may be used within a range that does not impair the object of the present invention.

Further, in order to improve the handling property of the film, it is common to add inert particles as a lubricant, and the inert particles include colloidal silica, calcium carbonate, titanium dioxide, alumina, aluminum silicate, Particles such as crosslinked polystyrene and silicone are used.

The inert particles may be contained in the resin at any stage before the melt extrusion step, for example, before, during or after the polymerization of the resin polymer. It may also be performed during the melt extrusion preparation step. Further, as a method of incorporating the particles into the resin, for example,
When it is contained in the polyester, it is preferable to disperse the particles in the form of slurry in ethylene glycol which is a diol component and polymerize the ethylene glycol with a predetermined dicarboxylic acid component. When the particles are added, for example, if the water sol or alcohol sol obtained during the synthesis is added without once drying, the dispersibility of the particles is very good and the electromagnetic conversion characteristics can be improved. Also effective is a method in which an aqueous slurry of particles is directly mixed with a predetermined polyester pellet and supplied to a vent type twin-screw kneading extruder and kneaded into polyester. As a method of adjusting the content of particles, it is effective to prepare a high-concentration particle master by the above method, and dilute it with a polyester that does not substantially contain particles during film formation to adjust the content of particles. Is.

In the film of the present invention, different polymers may be blended for the purpose of increasing the strength, etc., within the range that does not impair the object of the present invention, and an antioxidant, a heat stabilizer, and an ultraviolet ray. Organic additives such as absorbers, light-shielding agents and antistatic agents may be added to the extent that they are usually added.

Next, a method for obtaining the film roll of the present invention will be described. There are a center wind method and a surface wind method as a method of winding the above film into a roll. Either method may be selected to obtain the roll of the present invention. The surface wind method, in which the pressure can be controlled, is preferable. The winding conditions are not particularly limited, but the following conditions are generally used. That is, the winding tension is 8 to 12 kg /
m, winding contact pressure 30 to 60 kg / m, winding speed 100 to 200 m
The value of / minute is preferable in terms of the appearance of the film roll. In particular, when winding a film with a width of 1 m and a length of 10,000 m, the winding tension is 10 to 12 kg / m and the winding contact pressure is 40 to 60.
The range of Kg / m and the winding speed of 130 to 180 m / min is preferable in terms of preventing wrinkles that occur over time.

[0021]

【Example】

[Measurement method of physical properties and evaluation method of effect] (1) Film surface roughness (SRa) Three-dimensional fine shape measuring instrument (Model ET-30H of Kosaka Laboratory)
K) and three-dimensional surface roughness analysis system (model MARM
EC-3D) was used to measure the three-dimensional surface roughness (center plane average roughness). The conditions were as follows, and the value was an average value of 20 measurements.

-Stylus tip radius: 0.5 μm-Stylus load: 4 mg-Vertical magnification: 50,000 times-Horizontal magnification: 200 times-Cutoff: 0.25 mm-Feeding pitch: 5 μm-Measuring length: 500 μm・ Measuring area: 0.197 mm ²・ Measuring speed: 100 μm / sec

(2) Thermal expansion coefficient (α _TF ) of the film The measurement was performed according to the measuring method of JIS K 7197.

(3) Coefficient of thermal expansion (α _TC ) of the winding core A core having an outer diameter of 167 mm, an inner diameter of 152.5 mm and a length of 50 mm is placed on an L-shaped surface plate inclined 5 ° from the horizontal, and the temperature is 60 ° C.
The test core heated to the above was gradually cooled, and the outer diameter displacement of the test core with respect to the temperature change was measured with a dial gauge.

(4) Surface roughness (Ra) of winding core According to JIS B 0601, a surface roughness meter Surfcom 111A manufactured by Tokyo Seimitsu Co., Ltd. was used to cut off 0.2.
The center line average roughness was measured at 3 points at 5 mm, and the average value was taken as the surface roughness.

(5) Axial elastic modulus (Ya) of winding core Outer diameter 167 mm, inner diameter 152.5 mm, length 1200 m
The core of m was supported so that the distance between fulcrums was 900 mm, a load was applied to the center of the core, and the elastic modulus in the axial direction was calculated from the load-deflection ratio.

(6) Circumferential Elastic Modulus (Yr) of Winding Core A core having an outer diameter of 167 mm, an inner diameter of 152.5 mm and a length of 50 mm is placed between two flat plates, and a load is applied to the center to apply a load- The elastic modulus in the circumferential direction was calculated from the deflection ratio.

(7) Evaluation of "wrinkle" due to temperature change After leaving the film roll for 7 days under the conditions of temperature 40 ° C and humidity 65%, it was carried into the condition of temperature 25 ° C, humidity 65%,
After standing for 6 hours, a film of 300 m was unwound from the winding core, and the presence or absence of “wrinkles” due to temperature change was confirmed.
The "wrinkles" were all checked visually. The "wrinkle" was judged by the following method.

◎: Free tension without wrinkles ○: Free tension with wrinkles disappears at 3 kg / m tension ×: Free tension with wrinkles even at 3 kg / m tension What does not disappear

Example 1 As additives, 0.1% of divinylbenzene / styrene copolymer crosslinked particles having an average particle size of 0.3 μ and 0.8 μ respectively were added.
Polyethylene terephthalate containing 5% by weight and 0.01% by weight was prepared, melt-extruded from an extruder, and cast on a cooling roll through a slit die to obtain an unstretched sheet. This unstretched film was stretched 4.0 times in the longitudinal direction at 90 ° C. This uniaxially stretched film was stretched 4.2 times in the width direction at the same temperature as in the longitudinal direction using a tenter, and further stretched 1.5 times in the longitudinal direction at 150 ° C.,
Heat treatment at 180 ℃ for 5 seconds under constant length, film thickness 4
A film raw material having a film surface roughness (SRa) of 0.011 μm was obtained. This raw film is used as a fiber reinforced plastic (FWP) core A (Tenryu Kogyo Co., Ltd. FWP-
201) using a surface center wind type slitter, a film roll having a width of 1 m and a length of 10,000 m has a winding tension of 10 kg / m, a winding contact pressure of 50 kg / m, and a winding speed of 1
Winded up at 50 m / min.

Example 2 Polyethylene 2,6-naphthalate containing 0.3% by weight of colloidal silica particles having an average particle size of 0.2 μ and 0.01% by weight of calcium carbonate particles having an average particle size of 0.8 μ as additives. It was prepared, melt-extruded from an extruder, and cast on a cooling roll through a slit die to obtain an unstretched sheet. This unstretched film was stretched 4.1 times in the longitudinal direction at 135 ° C. This uniaxially stretched film was stretched 4.5 times in the width direction at 115 ° C. using a tenter, and further stretched 1.2 times at 150 ° C. in the longitudinal direction, and then 180 times under a constant length.
The film was heat-treated at 5 ° C. for 5 seconds to obtain a film original film having a film thickness of 4 μm and a film surface roughness (SRa) of 0.008 μm. This film original fabric was slit under the same conditions as in Example 1 to obtain a film roll.

Example 3 An aromatic polyamide solution polymerized from N-methylpyrrolidone, 2-chloroparaphenylenediamine, 4,4'-diaminodiphenyl ether and terephthalic acid chloride was uniformly distributed at 30 ° C on a surface-polished metal drum. It was cast and dried in an atmosphere of 150 ° C. for 5 minutes. The film was peeled from the belt and continuously immersed in a water tank at 20 ° C. for about 10 minutes to extract the solvent and the inorganic salt and stretched 1.05 times in the longitudinal direction. Further, the film was introduced into a tenter and stretched 1.1 times in the width direction at 300 ° C. to obtain a film original film having a thickness of 4 μm and a film surface roughness (SRa) of 0.003 μm. This film original fabric was slit under the same conditions as in Example 1 to obtain a film roll.

Example 4 The same as Example 1 except that the winding core was changed to a fiber reinforced plastic (FWP) core B (FWP-01 manufactured by Tenryu Kogyo KK) when the film roll of Example 1 was obtained. A film roll was obtained under the conditions.

Example 5 The same as Example 1 except that when the film roll of Example 2 was obtained, the winding core was changed to a fiber reinforced plastic (FWP) core B (FWP-01 manufactured by Tenryu Kogyo KK). A film roll was obtained under the conditions.

Comparative Example 1 The original film of the film obtained in Example 1 was rewound at 200 ° C.
Was subjected to heat treatment for 10 minutes to obtain a film original film having a film thickness of 4 μm and a film surface roughness (SRa) of 0.011 μm. This raw fabric was slit under the same conditions as in Example 1 to obtain a film roll.

Comparative Example 2 When obtaining the film roll of Example 2, the winding core was a fiber reinforced plastic (FWP) core C (Tenryu Kogyo KK).
A film roll was obtained under the same conditions as in Example 2 except that the film roll was changed to (Production).

Comparative Example 3 When obtaining the film roll of Example 1, a film roll was obtained under the same conditions as in Example 1 except that the winding core was changed to a paper core (MA core manufactured by Showa Marutsu Co., Ltd.). It was

Comparative Example 4 In obtaining the film roll of Example 2, a polyvinyl chloride (PVC) core (manufactured by Showa Marutsu Co., Ltd.) was used as a winding core.
A film roll was obtained under the same conditions as in Example 2 except that

Table 1 summarizes the physical property values of the films and the winding cores and the occurrence of "wrinkles" due to temperature changes.

The film rolls of Examples 1 to 5 satisfying the requirements of the present invention do not cause "wrinkles" due to temperature change as shown in Table 1 and have no convex deformation portion on the film surface. On the other hand, the film rolls of Comparative Examples 1 to 4 are examples that do not satisfy the requirements of the present invention, but "wrinkles" occur due to temperature changes.

[0041]

[Table 1]

[0042]

Although the film roll of the present invention described above is a conventional thin film and smooth film, it has a "wrinkle" in the vicinity of the winding core caused by thermal expansion and contraction of the film due to environmental changes, especially temperature changes. Can be avoided,
Its industrial value is high.

Claims (10)

[Claims] 1. A film roll having a film and a winding core, wherein the film thickness is 20 μm or less, and the coefficient of thermal expansion of the winding core and the film satisfies the following formula (1). ｜ α _TF −α _TC ｜ ≦ 15.0 × 10 ^-6 (1) α _TF : Thermal expansion coefficient of film (/ ℃) α _TC : Thermal expansion coefficient of winding core (/ ℃) 2. The film roll according to claim 1, wherein the coefficient of thermal expansion of the winding core and the film satisfy the following expression (2). ｜ α _TF −α _TC ｜ ≦ 8.0 × 10 ^-6 (2) α _TF : Thermal expansion coefficient of film (/ ℃) α _TC : Thermal expansion coefficient of winding core (/ ℃) 3. The three-dimensional surface roughness (SRa) of at least one side of the film is 0.02 μm or less.
Alternatively, the film roll described in 2. 4. The surface roughness (Ra) of the winding core is 0.
The film roll according to claim 1, which has a thickness of 5 μm or less. 5. The film roll according to claim 1, wherein the three-dimensional surface roughness (SRa) of at least one surface of the film is smaller than the surface roughness (Ra) of the winding core. 6. The film roll according to claim 1, wherein the winding core has an axial elastic modulus (Ya) of 1000 kg / mm ² or more. 7. The elastic modulus (Yr) in the circumferential direction of the winding core.
Is 1000 kg / mm ² or more, The film roll according to claim 1. 8. The film roll according to claim 1, wherein the winding core is a core having a fiber reinforced plastic as a base material. 9. The film roll according to claim 1, wherein the base material is one selected from the group consisting of a polyester resin, a polyolefin resin, a polyamide resin, and a polyphenylene sulfide resin. 10. The polyester resin is ethylene terephthalate, ethylene 2,6 naphthalate, and ethylene α, β-bis (2-chlorophenoxy) ethane-.
The film roll according to claim 1, which is a resin having at least one selected from the group consisting of 4,4′-dicarboxylate as a main structural unit.