JPH10305542A - Gas barrier polyester film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas barrier polyester film having excellent processability and gas barrier properties. SOLUTION: A gas barrier layer is provided on an A-surface of a base film made of polyester resin. When surface roughnesses of A and B surfaces of the film are indicated by ARa, BRa, ARa<BRa, ARa<=0.05 μm, 0.02 μm<=BRa<=0.37 μm are satisfied. And, maximum heat shrinkage factor of lengthwise and lateral directions of the film are 50 to 500 g/mm<2> , and heat shrinkage factor of a lengthwise direction at 190 deg.C of the film is a range of -1.5 to 6%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film for a gas barrier, and more particularly to an inorganic thin film or an inorganic oxide film formed on a base film made of a polyester resin by a vapor deposition method, an electron beam method, a gas phase polymerization method, a sputtering method, or the like. The present invention relates to a polyester film for a gas barrier, which can exhibit good gas barrier properties by providing the same.

[0002]

2. Description of the Related Art Conventionally, various films for gas barrier have been proposed, but it has been difficult to achieve both good gas barrier properties and good workability, especially good yield.

[0003] In the gas barrier film, the characteristics of the base film, particularly the gas barrier layer provided on the base film, are the gas barrier properties of the obtained gas barrier film, the processability in processing the gas barrier film, and furthermore, The quality of the gas barrier property resulting from the workability greatly affects the quality.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to control and define various characteristics of a base film, thereby providing excellent film forming properties of a base film, excellent workability when forming a film for a gas barrier, and excellent gas barrier properties. An object of the present invention is to provide a polyester film for a gas barrier which can achieve excellent gas barrier properties when the film is used as a film.

[0005]

In order to solve the above-mentioned problems, a polyester film for a gas barrier according to the present invention has a gas barrier layer on the A side of a base film made of a polyester resin, and has a gas barrier layer on the A side of the base film. When the surface roughness of the surface B is ARa and BRa, respectively, it satisfies ARa <BRa, ARa ≦ 0.05 μm, 0.02 μm ≦ BRa ≦ 0.3 μm, and the maximum in the longitudinal and width directions of the base film. Each heat shrinkage stress is 50 g / mm ^{2 to} 500 g / mm
^{2, wherein} the heat shrinkage in the longitudinal direction at 190 ° C. of the base film is in the range of −1.5% to 6%.

In such a polyester film for a gas barrier, by making the surface A of the base film a relatively flat surface having a surface roughness of a specific value or less, the adhesion to the gas barrier layer is improved and the gas barrier of the thin film is improved. Even in the case of a layer, a desired layer form can be easily maintained, and good gas barrier properties are exhibited. In addition, B of base film
By making the surface a surface in a specific range having a relatively large surface roughness, the friction coefficient is suppressed to be low, the running property and the handling property are improved, and the workability when the film is used as a gas barrier film can be maintained well. In addition, good gas barrier properties can be ensured by preventing the surface roughness from becoming too large. Further, by controlling the maximum heat shrinkage stress and the heat shrinkage rate of the base film in the optimum ranges, it is possible to exhibit excellent gas barrier properties by cooperating with the gas barrier layer while ensuring good workability.

[0007] By keeping all these characteristics within a predetermined range, a polyester film for gas barrier can be obtained as
Comprehensively, it is possible to achieve both excellent workability and excellent gas barrier properties.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the polyester film for gas barrier of the present invention will be described below. The polyester film for a gas barrier according to the present invention has a base film made of a polyester resin, and a gas barrier layer provided on the A surface of the base film.

Examples of the polyester resin constituting the base film include, as an acid component, an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; and a fatty acid such as adipic acid, sebacic acid, dodecadionic acid, and azelaic acid. Alicyclic dicarboxylic acids such as aliphatic dicarboxylic acids and cyclohexane dicarboxylic acids; and aliphatic diols such as ethylene glycol, diethylene glycol and butanediol as alcohol components, and polymers obtained by combining one or more of these acid components and alcohol components. Can be used. Also, a blend of two or more of such polymers may be used. Among them, polyethylene terephthalate or polyethylene-2,6-naphthalate is preferred in terms of mechanical properties.

Although the intrinsic viscosity of the polymer is not particularly limited, it is preferably in the range of 0.4 to 1.8.

Various additives may be added to the polyester resin as required. As the additive, various inorganic and organic particles can be used, and the particle shape is also,
Various shapes such as true spherical particles, aggregated particles, scale-like particles, and beaded particles can be used. As the organic particles, those made of a non-thermoplastic resin such as cross-linked polystyrene, cross-linked acrylic resin, fluororesin, and imide resin can also be used. Of course, thermoplastic resins such as various kinds of nylon, polyethylene, polypropylene, polystyrene, 4-methylpentene-1, and silicone resin can also be used.

The base film made of the polyester-based resin as described above is constituted so that its characteristics are controlled as follows.

First, the surface on which the gas barrier layer is provided is designated as A
Surface, the opposite surface is defined as surface B, and the surface roughness of surface A is ARa, B
When the surface roughness is set to BRa, it is necessary to satisfy ARa <BRa, ARa ≦ 0.05 μm, and 0.02 μm ≦ BRa ≦ 0.3 μm.

If ARa> 0.05 μm, it may be difficult to form a desired thin film gas barrier layer, and the gas barrier properties become insufficient. Also, BRa <0.
When the thickness is 02 μm, the friction coefficient of this surface increases, and the running property and the handling property deteriorate, so that the workability becomes insufficient. Further, when BRa> 0.3 μm, the surface roughness becomes too large, which is considered to have an adverse effect on the back surface during barrier processing. However, the gas barrier property is deteriorated, and especially when a water-based paint is applied to the B surface. The coatability of the film deteriorates, and the gas barrier property also becomes insufficient.

The base film having the different surface roughnesses on the side A and the side B can be typically formed by a laminated film formed by a co-extrusion method. That is, by adjusting the particles contained in the film layer forming the A surface and the film layer forming the B surface, the A and B surfaces having a desired surface roughness can be easily formed.

The maximum heat shrinkage stress in the longitudinal direction and the width direction of the base film is 50 g / mm ^{2 to} 500 g, respectively.
/ Mm ² . If the maximum heat shrinkage stress is less than 50 g / mm ² , the base film itself is easily stretched, so that it becomes difficult to handle when processing into a gas barrier film, and it becomes difficult to provide a desired gas barrier layer. As a result, gas barrier properties may be insufficient. Conversely, if the maximum heat shrinkage stress exceeds 500 g / mm ² , the heat shrinkage stress is too high, which may cause deformation of the base film itself or deformation of the gas barrier layer during processing. As a result, the gas barrier property may be insufficient.

Further, the heat shrinkage in the longitudinal direction at 190 ° C. of the base film must be in the range of -1.5% to 6%. When the heat shrinkage exceeds 6%, the deformation of the film at the time of processing becomes large, and it becomes difficult to provide a desired gas barrier layer, and as a result, the gas barrier property may be insufficient. On the other hand, if it is less than -1.5%, that is, if the elongation of the film exceeds 1.5%, it becomes difficult to uniformly form a thin gas barrier layer.

As described above, in the present invention, all of the surface roughness of the surface A and the surface B of the base film, the maximum heat shrinkage stress in the longitudinal direction and the width direction, and the heat shrinkage rate in the longitudinal direction are controlled within predetermined ranges. Is done. A gas barrier layer is provided on side A of the base film.

The method for forming the gas barrier layer is not particularly limited, and may be, for example, a vapor deposition method, an electron beam method, a gas phase polymerization method, a sputtering method, or the like.

As the gas barrier layer, for example, an inorganic thin film or an inorganic oxide thin film (transparent thin film, opaque thin film) can be formed, and an organic resin-based gas barrier layer can be further provided thereon.

As the inorganic gas barrier layer, for example,
_{Al, Al 2 Ox, SiOx,} MgOx, alone of such CaOx, the mixture can be used, these resistance heating high-frequency induction heating, it is possible to form a desired film by vacuum deposition by electron beam heating. The thickness is preferably in the range of 50 to 2000 angstroms. When the inorganic gas barrier layer is provided, it is preferable to perform a glow discharge treatment in advance, or to provide a polymer thin film of various acrylics or modified acrylics by a gas phase polymerization method, since the barrier properties are further improved.

As the organic resin, various olefins,
Modified olefins, nylon, modified nylon and the like can be used, and among them, polyvinyl alcohol, polyvinylidene chloride, ethylene vinyl alcohol copolymer, polyacrylonitrile, etc. can be preferably used,
These can be provided by a gas phase polymerization method or various coating methods. The thickness is preferably in the range of 5 ° to 5 μm.

In the polyester film for a gas barrier according to the present invention, a water-based paint may be applied to the side B of the base film, and the water-based paint may be stretched together with the base film during stretching. The water-based paint is not particularly limited, and may be selected according to the purpose, for example, further improving the gas barrier property, or improving the handling property and the antistatic property of the base film.
However, from the viewpoint of preventing trouble during processing, it is preferable that the water-based paint does not contain inorganic lubricant particles. When a lubricant is added, organic particles having a softening temperature of 180 ° C. or lower are preferred.

The polyester film for a gas barrier according to the present invention as described above can be produced, for example, by the following method. In the polyester resin, added during polymerization,
Two or more types of raw materials to which a predetermined amount of particles are added as necessary are combined by a method such as addition at the time of melt-kneading or mixing of a high-concentration particle master raw material with a predetermined amount of raw material.
After drying to 50 ppm or less, it is melted using an extruder. 2
At least one kind of molten resin is laminated, extruded into a sheet shape from a die, and cooled on a cooling roll. The obtained sheet is stretched in the longitudinal direction at 70 to 120 ° C. by 2.5 to 7 times, and further stretched in the width direction at 80 to 150 ° C. by 2.5 to 7 times. 100-150 ° C in the longitudinal direction again if necessary
May be stretched 1.05 to 3 times. Also, the stretching may be sequential stretching, but stretching in the longitudinal direction and the width direction at the same time,
This is preferable because there are few surface defects such as scratches and the barrier properties are stable. Re-stretching in the longitudinal direction and / or the width direction may be further added to the simultaneous biaxial stretching. The heat treatment is not particularly limited, but is usually performed at a temperature of 100 to 250 ° C., as necessary, with a relaxation treatment of 0 to 15%.

By forming a base film comprising such a laminated film, the surface A having the surface roughness specified in the present invention can be obtained.
The B-side can be obtained, and it is possible to control the maximum heat shrinkage stress and the heat shrinkage in a predetermined range.

A predetermined gas barrier layer may be provided on the obtained base film, and if necessary, an aqueous paint layer may be provided on the side B of the base film during or after the film formation.

[Measurement method] The measurement method of each characteristic used in the description of the present invention is as follows. (1) Surface roughness The center line average roughness was measured according to JIS-B-0601.

(2) Maximum heat shrinkage stress A tension of 40 g / mm ² was applied at room temperature, the temperature was raised at 10 ° C./min, and the maximum shrinkage stress was measured.

(3) Heat Shrinkage The heat shrinkage after heating at 190 ° C. for 30 minutes was measured according to JIS-C2318.

(4) Gas Barrier Property A film provided with a 150 ° aluminum oxide thin film on the surface A was measured for the amount of oxygen and moisture per m ² for 24 hours.

(5) Film-forming properties When a film having a width of 2.5 m and a thickness of 12 μm was wound up at 40,000 m at 200 m / min, a wrinkle was evaluated as x, and a wrinkle-free film was evaluated as o.

[0032]

EXAMPLES Hereinafter, specific examples of the present invention will be described.
A description will be given in comparison with a comparative example. Examples 1 to 5 and Comparative Examples 1 to 5 To the raw materials A and B of polyethylene terephthalate having an intrinsic viscosity of 0.65, predetermined amounts of silica particles having respective particle diameters were added as shown in Tables 1 and 2 to adjust the water content to 20 ppm. After drying, 28
It was extruded at 0 ° C. into a laminated sheet of layers A and B and cooled on a roll at 30 ° C. The stretching condition in the longitudinal direction is a stretching temperature of 115.
℃, stretching ratio 3.8 times, stretching condition in the width direction is stretching temperature 12
The heat treatment temperature was 228 ° C. (Examples 1 to 3 and Comparative Examples 1 to 3), 200 ° C. and the draw ratio was 3.6 times.
C. (Comparative Example 4), 245 ° C. (Comparative Example 5), 219 ° C. (Example 4), and 234 ° C. (Example 5). The relaxation rate was 10% in Comparative Example 5, and 2.5% in the others.

Example 6 A water-based paint containing crosslinked acrylic particles having a softening temperature of 150 ° C. and a particle size of 1 μm was applied to an acrylic resin on a single-layer film stretched in the longitudinal direction, and then stretched in the width direction. Other conditions were the same as those in Example 1. However, the coating of the water-based paint has a coating thickness of 0.1% on the final film.
It was applied so as to have a thickness of 2 μm, and the gas barrier layer was applied on the non-coated surface (A surface).

Example 7 On the gas barrier layer of the polyester film for gas barrier obtained in Example 6, a polyvinyl alcohol film having a thickness of 500 ° was further provided by a gas phase polymerization method.

Example 8 A film was formed in the same manner as in Example 1 except that a polyethylene-2,6-naphthalate resin having an intrinsic viscosity of 0.68 was used. However, longitudinal stretching was performed at 105 ° C, and transverse stretching was performed at 110 ° C.

Example 9 A film was formed and evaluated under the same conditions as in Example 1 except that simultaneous biaxial stretching was performed at 98 ° C., 3 times in the longitudinal direction and 3.5 times in the width direction as stretching conditions.

Example 10 A film was formed and evaluated under the same conditions as in Example 1 except that a glow discharge treatment was performed before providing the aluminum oxide thin film.

The results are shown in Tables 1 and 2. As shown in Tables 1 and 2, the polyester films for gas barrier according to the examples within the range specified in the present invention exhibited excellent gas barrier properties and film-forming properties (workability), but not comparative examples. In the film according to the above, both the gas barrier property and the film forming property could not be satisfied at the same time.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

As described above, according to the polyester film for gas barrier of the present invention, by controlling various characteristics of the base film to a specific range, the film forming property of the base film and the polyester film for gas barrier can be improved. And the gas barrier properties of the resulting polyester film for gas barrier.

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI B32B 7/02 B32B 7/02 9/00 9/00 A 27/30 27/30 C 102 102 // B29K 27:00 67:00 B29L 7 : 00 9:00

Claims (8)

[Claims] 1. A base film made of a polyester resin having a gas barrier layer on the A surface, and when the surface roughness of the A surface and the B surface of the base film are ARa and BRa, respectively, ARa <BRa, ARa ≦ 0.05 μm, 0.02 μm ≦ BRa ≦ 0.3 μm, and the maximum heat shrinkage stress in the longitudinal and width directions of the base film is 50 g / mm ^{2 to} 500 g / mm, respectively.
^2. A polyester film for a gas barrier, wherein the heat shrinkage in the longitudinal direction at 190 ° C. of the base film is in a range of −1.5% to 6%. 2. The polyester film for a gas barrier according to claim 1, wherein the gas barrier layer comprises an oxide deposited film. 3. The polyester film for gas barrier according to claim 1, wherein a water-based paint is applied to the B side of the base film. 4. The polyester film for gas barrier according to claim 3, wherein the water-based paint does not contain lubricant particles. 5. The polyester film for gas barrier according to claim 1, wherein the surface A of the base film is subjected to a glow discharge treatment. 6. The polyester film for a gas barrier according to claim 1, wherein an organic resin-based gas barrier layer is further provided on the gas barrier layer. 7. The polyester film for a gas barrier according to claim 5, wherein the organic resin-based gas barrier layer is made of a polyvinyl alcohol-based resin or a polyvinylidene chloride-based resin. 8. The polyester film for a gas barrier according to claim 1, wherein the polyester film is at least simultaneously biaxially stretched.