JP3235694B2 - Laminated polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated polyester film, and more particularly, to a polyester film having good antistatic properties in which a polyaniline component containing at least a sulfonic acid group is laminated on one side of the polyester film.

[0002]

2. Description of the Related Art Polyester films are excellent in heat resistance, dimensional stability, mechanical strength and the like, and are used in a large amount and in a wide range. However, it has been pointed out that one of the obstacles in use of the polyester film is caused by static electricity. In particular, there is a demand for an inexpensive polyester film free from static electricity in a low humidity environment.

[0003]

SUMMARY OF THE INVENTION The present invention has been accomplished as a result of intensive studies in view of the above circumstances, and the object of the present invention is to make use of the excellent point of the original polyester film and to solve the drawback of the polyester film. An object of the present invention is to provide an inexpensive polyester film that overcomes obstacles.

[0004]

The above object can be attained by a laminated polyester film wherein a polyaniline containing a sulfonic acid group is laminated on at least one surface of the polyester film.

[0005] Further, for example, in applications where the adhesion between the base polyester film and the magnetic layer or other laminate is strongly required, at least one layer of polyester, polyurethane, polyacrylate having an anionic group or the like is coated. Preferably, a laminated polyester film is characterized in that a copolymerized polyester containing a sulfonic acid group is laminated on at least one surface of the laminated polyester film, and the copolymer is used as an anchor coat of polyaniline. The use of polyester improves the adhesion of the polyaniline to the substrate.

[0006] The laminated polyester film of the present invention, particularly when used for magnetic recording media, has good quality due to its antistatic properties and the effect of improving adhesiveness.

Further, the laminated polyester film of the present invention has a surface resistance of a surface of the laminated polyester film on which polyaniline having a sulfonic acid group is laminated, of 2
In the case of a laminated polyester having a degree of 10 ⁷ to 10 ¹¹ Ω / □ at 3 ° C. and a relative humidity of 15%, it is possible to provide the most economical polyester film which can overcome the above-mentioned electrostatic obstacle.

In the polyester film of the present invention, 90 mol% or more, preferably 95 mol% or more of the repeating unit is ethylene terephthalate or ethylene-2,6.
-Naphthalate, and may contain a known copolymer component as another component. In order to form fine projections on the film surface, known inert fine particles such as silica, calcium carbonate, kaolin, and alumina may be contained as a lubricant.

The polyaniline containing a sulfonic acid group in the present invention is represented by the general formula (Chemical Formula 1).

[0010]

Embedded image

(In the formula (1), R 1, R 2 and R 3 are a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and x is 50 to 2
000, preferably an integer of 100 to 1500. The compound represented by the general formula (Formula 1) used in the present invention is described in J. Am. Am. Chem. Soc. , 1991, 11
It can be manufactured according to the method described in 3,2665-2666. Compounds to which the present invention is applicable are those in which sulfonic acid groups are introduced into the aromatic ring at a ratio of 1/10 to 4/5, preferably 2/5 to 3/5. Since these are dispersed or dissolved in water, a coating method is most preferable as a lamination method, but is not limited thereto.

In the present invention, the term "copolymerized polyester containing sulfonic acid groups" means that the monomer containing sulfonic acid groups in the dicarboxylic acid component is one component, and the ratio of the monomer containing sulfonic acid groups to the total acid components is 1%. ~ 50 mol%
Is a copolymerized polyester. As the sulfonic acid group-containing dicarboxylic acid, 5-sodium sulfoisophthalic acid is preferred. Other carboxylic acid-based terephthalic acid, isophthalic acid, p-β-oxyethoxybenzoic acid, 2,6-naphthalenedicarboxylic acid,
Examples thereof include 4'-dicarboxydiphenyl, 4,4'-dicarboxylbenzophenone, bis (4-carboxylphenyl) ethane, adipic acid, sebacic acid, and cyclohexane-1,4-dicarboxylic acid. On the other hand, examples of the glycol-based component include, in addition to ethylene glycol, propylene glycol, butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, an ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like. Can be In addition, a small amount of a compound containing an amide bond, a urethane bond, an ether bond, a carbonate bond or the like may be contained as a copolymer component.

Further, the magnetic recording medium referred to in the present invention is a magnetic tape such as a video tape, an audio tape, a digital video tape, a digital audio tape, a floppy disk, a magnetic card or the like, on which a magnetic recording means is applied on a polyester film. It is. The surface resistance of the film of the present invention on which the polyaniline containing a sulfonic acid group is laminated is 10 ⁷ under an environment of 23 ° C. and 15% relative humidity.
It is necessary to be 〜１０10 ¹¹ Ω / □. This range is the most advantageous in terms of productivity and unit consumption without static electricity disturbance, and can provide a polyester film economically.

[0014]

The present invention will now be described by way of examples, which should not be construed as limiting the invention. In addition, in the example sentences, simply “parts” indicates parts by weight. The evaluation method used in the present invention is also shown below. (1) Surface resistance Measured by Takeda Riken Co., Ltd.
The measurement was performed at 3 ° C. and 15% RH.

(2) Average particle size of lubricant: Centrifugal sedimentation type particle size distribution analyzer (SA-CP, manufactured by Shimadzu Corporation)
The value at the integrated 50% point in the equivalent sphere diameter distribution obtained in 3) was used.

(3) Surface Smoothness The film surface of the upper layer was measured using a stylus type three-dimensional surface roughness meter (SE-3AK, manufactured by Kosaka Laboratories) under the conditions of a needle radius of 2 μm and a load of 30 mg in the longitudinal direction of the film. Measured over a measurement length of 1 mm with a cut-off value of 0.25 mm and 2 μm
Quantization width 0.00312 μm every other height direction data
To load the data into an external storage device. Such measurement is continuously performed at 2 μm intervals in the lateral direction of the film.
The measurement was performed over the width of 0.3 mm in the transverse direction of the film. The data in the height direction at this time is represented by h (i,
j) [i = 1 to 500, j = 1 to 150],
The value obtained by performing the calculation according to the following equation is expressed in units of μm, and is defined as TAR (three-dimensional average roughness).

[0017]

(Equation 1)

(4) Smoothness ASTM-D18 is obtained by superimposing the upper layers of two films.
Measured under the conditions of a temperature of 23 ° C., a relative humidity of 65% and a tensile speed of 200 m / min according to 94-63T, and the dynamic friction coefficient (μ
Indicated in d).

(5) Number of Coarse Protrusions Aluminum was vapor-deposited on the film surface of the upper layer, and a visual field of 5 mm ² or more was observed using a two-beam interference microscope (the light source was monochromatic light having a wavelength of 546 nm). The number of second or higher order interference rings was counted, converted to the number per 1 mm ² and displayed.

(6) Coating for evaluation of adhesion Co-γ-Fe ₂ O ₃ 100 parts Vinyl chloride / vinyl acetate copolymer 15 parts Urethane-modified saturated polyester resin 15 parts α-alumina (average particle diameter 0.5 μm) 3 Part Carbon black (average particle diameter 0.08 μm) 2 parts Toluene 105 parts Methyl ethyl ketone 105 parts Cyclohexanone 105 parts After mixing and dispersing for 12 hours using a ball mill with the above ingredients, 1 part palmitic acid 2 parts dodecyl stearate 2 parts oleic acid 2 parts Was added and mixed for an additional 30 minutes. Next, 10 parts of a 75% solids solution of a triisocyanate compound in ethyl acetate was added and mixed for an additional hour to prepare a paint for evaluation. Evaluation of adhesiveness The thickness of the paint for evaluation was 3 μm after drying on the test film.
After applying a magnetic field orientation treatment, drying at 60 ° C., calendering at 100 ° C., curing at 60 ° C. for 72 hours, and then applying 23 ° C. to the coated surface of the obtained film. Scotch tape (“No. 610” manufactured by 3M) under the atmosphere of × 50% RH (width 10 mm × length 1)
0 cm) was applied so that air bubbles did not enter, and a roll was pressed on this. Subsequently, 360 degree peeling was performed at a tensile speed of 1000 cm / min using Tensilon manufactured by Toyo Baldwin. The space between the chucks was 18 cm, and the adhesive portion was 5 cm.

(7) Blocking resistance Two films (3 cm × 3 cm) coated with sulfonic acid group-containing polyaniline were superposed on each other, and were coated with silicone rubber of 6 cm × 6 cm and the same size with a thickness of 7 mm. Sandwiched by both sides of the glass plate. This is 2k
After a load of g was applied and the film was allowed to stand in an atmosphere of 50 ° C. × 85% RH for 48 hours, the adhesion state when the film was peeled was observed. ：: No adhesion was observed at all. Δ: Adhesion of the film occurred in some places. ×: Adhesion occurred at the entire surface.

Comparative Example 1 (A) Preparation of Base Film: 4000 fine calcium carbonate particles having an average particle size of 0.5 μm
The polyethylene terephthalate dispersed at a concentration of ppm was melt-extruded at 290 ° C. and cooled with a cooling roll at 30 ° C. to obtain an unstretched film having a thickness of about 180 μm. The unstretched film was stretched 3.5 times in the longitudinal direction between a pair of rolls heated to 85 ° C. and having different peripheral speeds to obtain a base film. (B) Preparation of sulfonic acid group-containing polyaniline coating solution: 10 g of polyaniline (x = 400) in which sulfonic acid groups were introduced at a ratio of 1/2 to the aromatic ring was added to 1 liter of 0.1 M
It was dissolved in an aqueous trimethylamine solution with stirring. To this aqueous solution, 1 l of isopropanol was added while further stirring to prepare a coating solution.

(C) Preparation of laminated polyester film:
After passing the sulfonic acid group-containing polyaniline aqueous solution obtained in the above (B) through a filter having a pore size of 1.0 μm, the above (A)
Was applied to the surface of the base film obtained in the above by a bar coater method and dried at 70 ° C. with hot air. Next, 1
After stretching 3.5 times in the transverse direction at 30 ° C, 200-210
The resultant was heat-set at a temperature of 100 ° C. to obtain a biaxially stretched laminated polyester film having a thickness of 14.5 μm. The final coating amount of the coating agent (sulfonic acid group-containing polyaniline) on the film was about 0.04 g / m ² . Table 1 shows the physical properties of the obtained film.

Example 1 (A) Preparation of sulfonic acid group-containing polyester and aqueous dispersion: First, a sulfonic acid group-containing polyester was prepared by the following method. Dimethyl terephthalate 49 mol% as the dicarboxylic acid component, dimethyl isophthalate 49 using a molar% and 2 mole percent sodium 5-sulfoisophthalic acid with ethylene glycol 50 mol% and 50 mol% Neo pen chill glycol as glycol component ,
A transesterification reaction and a polycondensation reaction were performed by a conventional method. The glass transition temperature of the obtained sulfonic acid group-containing polyester was 69 ° C. The sulfonic acid group-containing polyester (300 parts) and n-butyl cellosolve (150 parts) were heated and stirred to form a viscous solution.
By gradually adding 0 parts, a uniform pale white aqueous dispersion having a solid content of 30% was obtained. This dispersion was further added to a mixture of equal amounts of water and isopropanol to prepare an aqueous dispersion of a sulfonic acid group-containing polyester having a solid content of 5%.

(B) Preparation of mixed coating solution Comparative Example 1 The coating solution of (B) and the aqueous dispersion of Example 1 (A) were in a ratio of 5: 1 (the weight ratio of polyaniline and polyester was 1: 1). ) To obtain the coating liquid of Example 1 . (C) Preparation of Film A base film was prepared in the same manner as in Comparative Example 1 except that the coating solution was changed, and then a laminated film was prepared. Adhesion amount of the final coating of the film was about 0.05 g / m ^2. Table 1 shows the physical properties of the obtained film.

Comparative Example 2 A film in which the coating liquid was not applied in Comparative Example 1 was used as Comparative Example 2 . Table 1 shows the physical properties of the obtained film.

As shown in Table 1, the laminated polyester film of the present invention has a small surface resistance even under low humidity while maintaining its original physical properties, and is excellent in antistatic properties and adhesiveness.

[0028]

The laminated polyester film of the present invention is
Since it has excellent antistatic properties at low humidity, it can be widely and suitably used as a substrate for magnetic recording media, general industrial films, various packaging films, and the like.

[0029]

[Table 1]

Continuation of the front page (56) References JP-A-4-328181 (JP, A) JP-A-1-139259 (JP, A) JP-A-5-504153 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) B32B 1/00-35/00

Claims (2)

(57) [Claims] 1. A sulfonic acid group-containing polyaniline and sulfonic acid on at least one surface of a polyester film.
A laminated polyester film, wherein a layer comprising a mixture with a group-containing polyester is laminated. 2. The laminated polyester film according to claim 1, wherein the polyaniline and the sulfone have a sulfonic acid group.
The surface resistance of the surface on which the layer made of the mixture with the acid group-containing polyester is laminated is 10 ⁷ at 23 ° C. and 15% relative humidity.
A laminated polyester film having a resistivity of from 10 to 10 ¹¹ Ω / □.