JPH1110812A - Para-aramid film roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a roll wherein there is no deformation on the appearance and the wound shape of the roll, and there is no generation of wrinkles on a film even when the roll of a para-aramid film is stored for a long period of time until it is supplied to a customer for manufacturing. SOLUTION: It is a roll of a para-aramid film 2 with a thickness of 1-9 μm, and a sheet-form moisture-absorbing materials 3a, 3b, 3c are arranged in a manner to be in contact with the surface of the roll, and the roll and the moisture-absorbing materials are wrapped and packaged using a packaging film 4. By this method, even in the case of a thin para-aramide film which has an unevenness in the thickness in the width direction, there is no generation of defects in the appearance and the wound shape of the roll during a long term storage, and vertical wrinkles do not generate on the film as well, and a slip of the winding and the generation of wrinkles, etc., do not generate during transport, and for these reasons, when the film is worked, process troubles due to the generation of wrinkles, etc., do not generate, and also, problems which lower the characteristics and the quality of a final product do not generate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a para-aramid film, and more particularly to a roll (film roll) of a para-aramid film.

[0002]

2. Description of the Related Art In order to protect a roll of a highly hygroscopic film such as a nylon film from absorbing moisture during storage or transportation before use, it is known to provide means such as moisture-proof packaging. Further, even for a polyester film having relatively low hygroscopicity, when it is used for applications requiring high-precision processing such as a magnetic tape, moisture-proof packaging is performed.

In recent years, a para-aramid film, which has attracted attention for its heat resistance and high mechanical properties, can satisfy the rigidity and heat resistance required for handling even a thin film. And aramid have been used as a base film for magnetic tapes for high-density recording, but aramid has an intermediate moisture absorption property between nylon and polyester, and the expansion of the film due to moisture absorption cannot be ignored,
Particularly in the case of a thin film, deformation of the film roll and wrinkling of the film often occur during storage.

[0004]

It has already been proposed to pack a roll of para-aramid film in a moisture-proof manner in order to prevent the deformation and wrinkling of the roll during storage, but the penetration of a small amount of moisture cannot be prevented. A continuous sharp wrinkle (hereinafter, referred to as "vertical wrinkle") along the winding direction of the roll occurs not only on the roll surface but also on the inner layer film. This is the cause of poor product performance. Furthermore, in addition to moisture-proof packaging, it has been practiced to simultaneously seal a desiccant such as silica gel inside the core cylinder around which the film is wound, but it was not effective for some reason.

[0005]

Means for Solving the Problems The present inventors have accumulated various analyzes and studies on the rolls of para-aramid film, and as a result, clarified the problem that the effects of the conventional moisture-proof packaging and the desiccant were not obtained. The present invention has been completed. That is, an object of the present invention is a roll of a para-aramid film having a thickness of 1 to 9 μm, in which a sheet-shaped hygroscopic material is disposed in contact with the surface of the roll, and the roll and the hygroscopic material are included using a packaging film. And a para-aramid film roll packaged.

The para-aramid film to which the present invention is directed is a film having a thickness in the range of 1 to 9 μm. If the thickness exceeds 9 μm, the rigidity of the film increases,
Therefore, the occurrence of vertical wrinkles, which is the subject of the present invention, is small. The para-aramid film of the present invention may be a film having a thickness variation in the width direction, and 1% of the average thickness.
In a roll of a film having the above-mentioned thickness variation in the width direction, the roll is particularly largely deformed due to moisture absorption, and the vertical wrinkles often reach the inner layer. Therefore, the effects of the present invention are remarkable, and this is a preferred embodiment. . A film having a thickness unevenness in the width direction exceeding 10% is not suitable for use in high-grade applications, and thus is not an object of the present invention.

[0007] The para-aramid of the present invention is an aromatic polyamide-based polymer substantially composed of units selected from the group consisting of the following structural units. —NH—Ar ₁ —NH— (1) —CO—Ar ₂ —CO— (2) —NH—Ar ₃ —CO— (3) wherein Ar ₁ , Ar ₂ , and Ar ₃ are each at least one. A divalent group containing an aromatic ring, (1) and (2)
Are substantially equimolar when present in the polymer.

In the present invention, in order to secure good mechanical performance and dimensional stability, Ar ₁ , Ar ₂ and A
Each of r ₃ must be a para-oriented group. Here, the para-oriented type means that the bonding direction of the main chain in the aromatic ring is located at the para-position, or the bonding direction of the main chains at both ends is coaxial or parallel in a residue composed of two or more aromatic rings. It means there is. Representative examples of such a divalent aromatic group include the following chemical formula 1.

[0009]

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Here, X is —O—, —CH ₂ —, —S
It is a group selected from O ₂ —, —S—, and —CO—.
Further, some of the hydrogen atoms of these aromatic rings may be substituted with groups such as a halogen group, a nitro group, a sulfone group, an alkyl group and an alkoxy group. Ar ₁ , Ar _2, and Ar ₃ may be at least two types, and may be the same or different from each other.

The polymer used in the present invention can be produced from a diamine, a dicarboxylic acid or an aminocarboxylic acid corresponding to each structural unit by a method known hitherto. Specifically, a method is used in which a carboxylic acid group is first derived into an acid halide, an acid imidazolide, an ester, and the like, and then reacted with an amino group. And a solid phase polymerization method. In the aromatic polyamide used in the present invention, groups other than those described above may be copolymerized in an amount of about 10 mol% or less, or other polymers may be blended. The most typical aromatic polyamide used in the present invention is poly-p-phenylene terephthalamide (PPTA).

Since para-aramid has a high melting point and cannot be melt-molded, it is dissolved in a solvent to prepare a solution (hereinafter referred to as "dope"), and formed into a film by a wet method, a dry method, or a dry-wet method. In the case of PPTA which is hardly soluble in an organic solvent, a polymer is dissolved in a strong inorganic acid such as concentrated sulfuric acid to form a dope, and a film is formed by a wet method.
As disclosed in Japanese Patent No. 4118, a method of once extruding in a liquid crystal state, optically isotropic, and then solidifying is preferably used. On the other hand, for example, in an aromatic polyamide soluble in an organic solvent such as chloro-substituted PPTA, hydrochloric acid by-produced during the polymerization is neutralized to make the polymerization reaction mixture as it is, and the wet method or the dry method, or the dry-wet method A film forming method is preferably used.

The method of forming the dope into a film is not particularly limited in the practice of the present invention, and may be a method of extruding directly from a die into a coagulation bath, a method of once casting from a die onto an endless belt, After coating the dope thereon with a doctor knife or other methods, there is a method of evaporating the solvent on a belt or guiding the solvent together with the belt to a coagulation bath for wet coagulation. If necessary, the film formed in this manner is subjected to a neutralization treatment of an acid produced as a by-product at the time of polymerization or an acid used for dissolution, and then water or hot water is used to remove a dissolution aid such as a solvent or an inorganic salt. Then, if necessary, the substrate is washed with an organic solvent.

The washed film is dried, but can be stretched prior to drying if desired. That is, the wet film before drying is applied in a direction of 1.01 to 1.0.
By stretching about four times, mechanical properties can be improved. Drying of the film is usually preferably performed under tension, under constant length, or while slightly stretching. As a method for performing such drying, for example, drying can be performed by fixing to a tenter dryer or a metal frame. The drying temperature is usually in the range of 100C to 300C.

The dried film is subjected to a heat treatment at 300 ° C. or more and 500 ° C. or less, if necessary, and then wound on a core to form a film roll. Here, the heat treatment can be performed under tension, under constant length, or in a relaxed state, and can be performed in two or more stages by a combination of these. In winding the film into a roll, it is also a preferred embodiment to wind the film while meandering in order to reduce the occurrence of uneven thickness and so-called gauge bands on the roll due to uneven thickness in the width direction of the film. In winding, it is also preferable to cut out the edges of the film and align the end faces of the roll.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments of the present invention, but the present invention is not limited thereto. FIG. 1 is a cross-sectional view showing an aramid film roll of the present invention. An aramid film 2 is wound on a core 1 in a roll shape, and is covered with a sheet-shaped hygroscopic material 3a and a packaging film 4; One end is wound and sealed with an adhesive tape 5.

In practicing the present invention, the material of the core 1 is not particularly limited, and fiber reinforced plastic (FR) made of a combination of glass fiber and epoxy resin, paper and phenol resin, carbon fiber and epoxy resin, and the like.
P), a metal such as stainless steel, a paper core impregnated with a resin, or a resin layer formed on the surface thereof, such as those conventionally used, are used as long as the effects of the present invention are not impaired. .

[0018] The sheet-shaped hygroscopic material may be integrally processed by means such as enclosing the hygroscopic agent in paper, nonwoven fabric, a porous film, or the like, or may be a sheet-like hygroscopic agent sealed between porous resin plates. The difference between conventional silica gel and the like stored in a bag is that the surface area and the film roll surface can be arranged widely and in contact with the roll. It is considered to have a favorable effect.

Examples of the hygroscopic agent include calcium chloride, calcium sulfate, activated alumina, zeolite, molecular sieves, and those obtained by complexing them with pulp,
A solid absorbent such as silica gel is suitable, and the type thereof is not limited as long as the object of the present invention is not impaired.
In FIG. 1, the sheet-shaped hygroscopic material 3a is arranged along both end surfaces of the roll 2 so as to cover almost the entire surface. However, it is not always necessary to arrange the sheet-shaped hygroscopic material 3a on both surfaces. However, the effect of the present invention can often be achieved even with a part thereof.

As shown in FIG. 2, it is also a preferred embodiment to arrange a sheet-shaped hygroscopic material 3b around the outermost layer of the roll 2. In this case, the sheet-shaped hygroscopic material 3b
Although it is preferable that the surface of the outermost layer of the roll 2 is completely covered, the effect of the present invention is often achieved even with a part of the outermost layer. Of course, it is also a preferred embodiment to arrange a sheet-shaped hygroscopic material simultaneously on the roll end face and the outermost layer of the roll.

If it is not desirable for the sheet-shaped moisture absorbent to directly contact the film roll, as shown in FIG. 3, the roll 2 is temporarily covered with a moisture-permeable sheet 7 and the moisture absorbent 3c is placed thereon. Then, wrapping with a wrapping film 4 from above may be preferably performed. Examples of the moisture-permeable sheet include a microporous film, synthetic paper, and a nonwoven fabric.

As the packaging film for carrying out the present invention, general-purpose polyethylene, polypropylene, polyester and the like are used. In order to further enhance the effect of the present invention, the packaging film has a moisture permeability of 10 g / m ^2.・
24 hr · atm or less, preferably 5 g / m ² · 24 h
It is a preferred embodiment to use a moisture-proof film of r · atm or less.

Examples of the moisture-proof film include a polyacrylonitrile film, a polyvinylidene chloride film, a polyvinylidene fluoride film, a para-aramid film, and the like, and a coextrusion method or a coating method of polyethylene or polypropylene and polyvinylidene chloride. Examples thereof include a composite film, a film in which cellophane is coated with polyvinylidene chloride, a film in which metal aluminum is laminated on a polyethylene film, a polyester film, or the like. The thickness of the packaging film is not particularly limited, but if the film is too thin, it may be damaged during handling or transportation, and if the film is too thick, the rigidity of the film is increased and handling problems are likely to occur, and usually 10 μm to 200 μm. It is selected within the range of the degree.

The method of sealing the packaging film is not particularly limited, as long as it can substantially prevent or suppress the invasion of moisture.
As shown in FIG. 2, a method of attaching or sticking to the core, a method of folding both ends of the film into the inner surface of the core, and pressing and sealing with a pad of the core, forming the packaging film 4 into a bag shape as shown in FIG. Adhesion method such as heating 4a is optionally used.

In the example of FIG. 1, the cushioning material 6 is
Although it is installed to protect the end face of the film roll 2 from above, it is preferable to install a cushioning material, a pad for preventing the end face from collapsing on the roll end face or the outermost layer of the roll, and omit these installations. It is also possible. In addition, in order to prevent damage during transport and improve handling,
It is also a preferred embodiment to store in a container such as a cardboard box.

In practicing the present invention, there are no restrictions on dimensions such as the outer diameter of the film roll and the film width. The dimensions and materials of the core are not limited as long as the effects of the present invention are not impaired. Hereinafter, embodiments and effects of the present invention will be described with reference to examples, but the present invention is not limited thereto. The percentages and the like in the examples are on a weight basis unless otherwise specified.

<Method of measuring characteristics> The method of measuring characteristic values according to the present invention is as follows. (1) Measurement method of thickness and thickness unevenness The thickness unevenness of the film was measured by a digital electronic micrometer (K351C type manufactured by Anritsu Corporation) using a measuring element having a diameter of 2 mm in the width direction of the film. The average thickness is represented by the average value of all the measured values, and the thickness unevenness is represented by a percentage of the difference between the maximum value and the minimum value with respect to the average thickness. (2) Methods of measuring strength, elongation, and elasticity The strength, elongation, and elasticity are values measured using a constant-speed elongation type elongation meter at a measurement length of 100 mm and a tensile speed of 50 mm / min. (3) Method for measuring moisture permeability According to ASTM, F-372, a sample was subjected to a temperature of 40 ° C. and 90%.
After standing for at least 24 hours in an RH environment, the measurement was performed under the same conditions.

<Manufacture of Film Roll Used in Examples and Comparative Examples> 99.9% of PPTA was prepared by previously dispersing 0.04 μm silica particles with an ultrasonic homogenizer so as to be 0.3% with respect to PPTA. The polymer was dissolved in concentrated sulfuric acid so that the polymer concentration became 12%, and the dope of PPTA was adjusted.

This PPTA dope was cast on a tantalum endless belt moving at a speed of 10 m / min from the die. Then, the dope is subjected to a moisture absorption treatment simultaneously with heating on the belt to convert the dope from a liquid crystal phase to an isotropic phase.
After coagulation in 40% sulfuric acid at 40 ° C., neutralization, washing with water, stretching 1.1 times in the machine direction, stretching 1.1 times in the transverse direction with a clip tenter, Dry with hot air while keeping the film, and then hold the film with a tenter for 4 hours.
After a heat treatment at 30 ° C., a width of 60
The film was sent to a winder while meandering in mm, and both ends of the film were removed by slitting, and a roll having a width of 508 mm and a length of 5000 m as one roll was manufactured. The average thickness of the obtained PPTA film is 4.5 μm.
The film has a thickness unevenness of 4.8% with a period of about 60 mm in the width direction, and the physical properties of the film are strength 41, 42 kg / mm ² , elongation 14, 12% in the length direction and the width direction, respectively.
The elastic modulus was 1480 and 1490 kg / mm ² .

(Embodiment 1) As shown in FIG.
On both ends of the roll of TA film, a donut-shaped sheet in which silica gel is sealed in a polyethylene flash non-woven fabric ("Luxer" manufactured by Asahi Kasei Corporation) is placed so as to cover the entire end face, and a polyester film is formed on the dough sheet from above. Vapor permeability of 1.5 g / m ² · 24 hr · atm
The package was wrapped with the following moisture-proof film, and the end of the film was strongly fixed to the end of the core with an adhesive tape so as to maintain the hermetically sealed state as shown in the figure. The roll wrapped in this manner is stored in a cardboard box and placed in a constant temperature and humidity room at 30 ° C. and 80% RH.
Left for months. When the roll after standing was taken out and observed for the appearance of the roll and the deformation of the film, no abnormality such as wrinkles occurred on both the surface and the inner layer of the roll.

Comparative Example 1 Example 1 was repeated in exactly the same manner as in Example 1 except that no silica gel sheet was provided. After leaving for one month, the roll is about 2-3m on the surface.
Many sharp vertical wrinkles having a width of m were generated. These wrinkles continued to the inner layer in a convex shape in the length direction of the film, and could not be eliminated by a drying treatment or the like.

(Example 2) A sheet obtained by processing calcium chloride as a hygroscopic material and a pulp into a sheet, and sandwiching it between porous films (ID Corporation)
Is wound around the roll surface once around the entire width as shown in FIG. 2 and disposed as a moisture-proof film having a moisture permeability of 4.0 g / m ^2.
・ 24hr ・ atm Varilon CX, type 24
L (Asahi Kasei Kogyo Co., Ltd .: trademark, composite film of polyvinylidene chloride-based resin and polyethylene) was placed in a bag, excess air was removed, and the entrance was heat-sealed. A doughnut-shaped foamed polyethylene plate cut out from the top of the moisture-proof film as shown in FIG. 2 was fitted into a core as a cushioning material. For further protection, a donut-shaped plywood was fitted into the core and stored in a cardboard box. After leaving for 3 months in the same atmosphere as in Example 1, the roll was taken out and subjected to an appearance inspection. As a result, no abnormality such as wrinkles occurred on both the surface and the inner layer of the roll.

(Comparative Example 2) Example 2 was repeated in the same manner as in Example 2, except that silica gel housed in a paper bag was used as the hygroscopic material and inserted into the core cylinder. Similarly, when observation was performed after standing for 3 months, vertical wrinkles occurred, and the vertical wrinkles reached the inner layer of the film roll.

Example 3 The sheet-shaped hygroscopic material used in Example 2 was placed on the surface and both end surfaces of a film roll.
The package was wrapped with a polyethylene film having a thickness of 30 μm, and the end face of the wrapping film was fixed to the end of the core as in Example 1. After leaving it in a normal room for one month, it was taken out and the roll surface was observed. No abnormality was found at all.

Comparative Example 3 Example 3 was repeated in exactly the same manner except that no sheet-shaped hygroscopic material was provided. 1 in the room
The roll after standing for months had many vertical wrinkles, and the wrinkles had reached the inner layer.

[0036]

According to the present invention, during roll storage, the roll has no appearance or winding defects, does not have any vertical wrinkles on the film, and does not have a roll or wrinkles during transportation. Since there is no such problem, no process troubles such as wrinkles occur when processing the film, and no problems such as deterioration of the characteristics and quality of the final product do not occur. It is useful when used for thermal transfer sheets and the like that require high-speed, high-quality printing.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of one embodiment of the aramid film roll of the present invention.

FIG. 2 is a cross-sectional view of another embodiment of the aramid film roll of the present invention.

FIG. 3 is a sectional view of still another embodiment of the aramid film roll of the present invention.

[Explanation of symbols]

 Reference Signs List 1 core 2 aramid film 3a, 3b, 3c sheet-shaped hygroscopic material 4 packaging film 5 sealing tape 6 cushioning material 7 moisture-permeable sheet

Claims (6)

[Claims] 1. A roll of a para-aramid film having a thickness of 1 to 9 μm, wherein a sheet-shaped hygroscopic material is disposed in contact with the surface of the roll, and the roll and the hygroscopic material are included using a packaging film. A para-aramid film roll characterized by being wrapped. 2. The para-aramid film roll according to claim 1, wherein a sheet-shaped hygroscopic material is disposed on the surface of the roll via a microporous film or a nonwoven fabric. 3. The para-aramid film roll according to claim 1, wherein the sheet-shaped hygroscopic material is arranged along at least one side of the roll end face. 4. The para-aramid film roll according to claim 1, wherein the sheet-shaped hygroscopic material is wound and disposed around the outermost layer of the roll. 5. The packaging film has a thickness of 10 g / m ² · 24 h.
The para-aramid film roll according to any one of claims 1 to 4, which is a moisture-proof film having a water permeability of r · atm or less. 6. The para-aramid film has a width of 1 to 5 in the width direction.
The para-aramid film roll according to any one of claims 1 to 5, which has a thickness variation of 10%.