JPH079647A - Laminate polyester film - Google Patents

Abstract

PURPOSE:To obtain a film whose abrasion resistance at traveling repeatedly is excellent and deterioration of image quality at dubbing is low by adding monoclinic or tetragonal zirconium oxide particle in one upmost outer layer of a laminate film consisting of two-layer structure. CONSTITUTION:As a polyester for constituting a laminate film, polyethylene terephthalate or polyethylene-2,6-naphthalene dicarboxylate which can form the film is preferable. Ordinarily, zirconium oxide particle can be obtained from zirconium ore to be produced naturally. The zirconium oxide particle can be produced by melting zircon sand, making oxy-zirconium chloride, and burning zirconium hydroxide. The zirconium oxide particle has a monoclinic or tetragonal crystal structure, and the monoclinic system and the tetragonal system may be mixed. The zirconium oxide particle is added in at least one utmost outer layer of the laminate film consisting of at least two-layer structure.

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 magnetic recording medium containing zirconium oxide particles having a specific crystal structure, which is particularly excellent in abrasion resistance during repeated running. The present invention relates to a laminated polyester film that causes little deterioration in image quality during dubbing for use.

[0002]

2. Description of the Related Art Generally, polyester such as polyethylene terephthalate has excellent mechanical properties and chemical properties, and is widely used as a molded product such as a film or a fiber.

However, when the polyester is processed into a molded product, there is a problem that productivity is lowered due to lack of slipperiness. As a way to improve such problems,
Conventionally, a method has been performed in which inert particles are dispersed in polyester to give unevenness to the surface of a molded product.

For example, JP-A-52-86471 discloses inorganic particles whose specific surface area is defined, and JP-A-59-171.
In Japanese Patent No. 623, a method using spherical colloidal silica having a diameter of 0.1 to 1 μm is proposed. However, since inactive particles generally lack affinity with the polyester,
Although these methods are effective in solving the problem of slipperiness, when formed into molded products, the wear resistance and scratch resistance cannot be made to a satisfactory level.

When the wear resistance of a molded product, for example, a film for magnetic tape is low, abrasion powder of the film is apt to be generated during the manufacturing process of the magnetic tape, resulting in coating omission in the process of applying the magnetic layer, resulting in , Cause magnetic recording dropout. In addition, when using a magnetic tape, in most cases, it is run while contacting with a recording / reproducing device, etc., so abrasion powder generated at the time of contact adheres to the magnetic body, and during recording / reproducing, dropout (drop / drop) of magnetic recording occurs. Out). Further, the generation of scrapes in the calendering process in the step of applying the magnetic layer significantly deteriorates workability in manufacturing the magnetic recording film.

When a molded product, for example, a film for a magnetic tape has low abrasion resistance, when a foreign substance is generated during the manufacturing process of the magnetic tape, a scratch is easily formed on the film surface, and as a result, the magnetic recording It causes dropouts, etc., and easily scratches the film surface when using magnetic tape at high speeds. Furthermore, in the application of magnetic recording media, with the increase in process speed such as the process of coating a magnetic layer and subsequently dubbing a video tape etc. to manufacture a soft tape etc., there is a drawback that the film surface is scratched by a contacting roll or guide. there were. In addition, the image quality is deteriorated during the dubbing, and the image quality when the video tape is formed, that is, S / N
There is a drawback that the (signal / noise ratio) is insufficient.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to provide a film which is excellent in abrasion resistance during repeated running and has little deterioration in image quality during dubbing.

[0008]

DISCLOSURE OF THE INVENTION The above-mentioned object of the present invention is to provide a laminated film in which monoclinic and / or tetragonal zirconium oxide particles are contained in at least one outermost layer of a laminated film having at least a two-layer structure. Polyester film.

As the polyester constituting the laminated film in the present invention, any polyester can be used so long as it can form a film, for example, polyethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene 2 , 6-naphthalene dicarboxylate, polyethylene-1,2-bis (2-chlorophenoxine) ethane-
Preferred are 4,4'-dicarboxylate and the like, with polyethylene terephthalate or polyethylene-2,6-naphthalene dicarboxylate being particularly preferred.

These polyesters have, as copolymerization components, dicarboxylic acids such as adipic acid, isophthalic acid, sebacic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid and ester-forming derivatives thereof, polyethylene glycol, diethylene glycol, Dioxy compounds such as hexamethylene glycol, neopetyl glycol, polypropylene glycol, oxycarboxylic acids such as Ρ- (β-oxyethoxy) benzoic acid and ester-forming derivatives thereof may be copolymerized. The zirconium oxide particles in the present invention can be usually obtained from naturally occurring zirconium ore, that is, zircon sand or badderite. Examples of the production method include a method in which the above-mentioned zircon sand is melted, passed through zirconium oxychloride, and calcined to give zirconium hydroxide.

The zirconium oxide particles thus obtained have various forms depending on the production conditions, such as monoclinic crystal, tetragonal crystal, cubic crystal, rhombohedral crystal, orthorhombic crystal, and a mixture of these crystal phases. It has been known. Also, in general,
As a stabilizer, calcium oxide, magnesium oxide,
Zirconium oxide particles have also been used, including yttrium oxide and the like.

The zirconium oxide particles in the present invention are
The crystal structure is monoclinic or tetragonal. Monoclinic and tetragonal may be mixed.

The crystal structure of such zirconium oxide particles has a diffraction angle of 2 in which the diffraction X-ray appears in the X-ray diffraction method.
It can be identified from the value of θ. A plurality of sets of standard 2θ values are known for each crystal structure. For example, the main 2θ values in the case of monoclinic crystals are 24.0, 24.4, 28.2, 3 and 2.
1.5, 34.2, 34.4, 35.3, 40.7, 4
9.3, 50.1, 50.6, 54.1, 55.4, and in the tetragonal system, 29.8, 34.0, 34.8, 49.
5, 50.1, 59.4 (degrees) and the like.

Such zirconium oxide particles can be obtained by, for example, a wet method among the above-mentioned production methods, by setting the firing temperature to about 500 ° C. to 2000 ° C.

In order to obtain good scratch resistance when formed into a film, the content of crystal structures other than monoclinic and tetragonal is preferably less than 50 wt%, particularly preferably 30.
It is less than wt%.

The content of zirconium oxide particles in the laminated film of the present invention is as follows:
0.01 to 30 parts by weight is preferable, and 0.05 to 10 parts by weight is particularly preferable.

The zirconium oxide particles used in the present invention have an average particle diameter of 0.0, which is less likely to cause film breakage during film production, has a small film surface roughness, and has good electrical characteristics.
05-3 μm, particularly 0.005-0.3 μm is preferable.

The polyester used in the laminated film of the present invention is prepared, for example, by a method in which zirconium oxide particles are mixed and stirred with a glycol solvent which is a target polyester starting material to obtain a dispersion slurry, which is added to a reaction system of thermoplastic polyester. Obtainable. The treatment method at this time may be, for example, ultrasonic waves or the like, instead of stirring, and a medium type mill such as a sand grinder may be used. In addition to the method of directly adding to the above-mentioned polymerization reaction system in blending with polyester,
For example, a method in which zirconium oxide particles are kneaded into a molten polyester is also possible. The former may be added to the polymerization reaction system at any time, but is preferably from before the transesterification reaction to before the pressure reduction of the polycondensation reaction. In the case of the latter kneading, a method of drying the particles and kneading into the polyester or a method of directly kneading in a slurry state under reduced pressure may be used. In consideration of dispersibility, a method of directly kneading in a kneader having a high shearing force in a slurry state under reduced pressure is preferable.

Particles other than the zirconium oxide particles of the present invention may be used in combination in order to obtain the running property of the film.

Examples of such particles include inorganic particles such as calcium carbonate, titanium oxide, silicon oxide and calcium phosphate, crosslinked polymer particles such as silicone, styrene-divinylbenzene copolymer and ethylvinylbenzene-divinylbenzene copolymer. Alternatively, there may be mentioned inactive particles such as so-called internal particles deposited by a polyester polymerization reaction system containing at least one of an alkali metal and an alkaline earth metal and phosphorus as a part of its constituent components.

The particle size of these particles is preferably larger than that of the zirconium oxide particles of the present invention, and is 0.1 to 2 μm.
m is preferred. The addition amount is 1
0.005 to 10 parts by weight is preferable with respect to 00 parts by weight.

In the laminated polyester film of the present invention, the film containing zirconium oxide particles must be at least one outermost layer of the laminated film having at least a two-layer structure, from the viewpoint of abrasion resistance and dubbing resistance. Is.

Further, when the laminated polyester film of the present invention has a structure of three or more layers, it is more preferable from the viewpoint of abrasion resistance and dubbing resistance. At this time, the film containing zirconium oxide particles has a three-layer structure. It is preferably at least one outermost layer of the laminated film. Further, it is particularly preferable that the particles are contained in both outermost layers.

When particles other than zirconium oxide particles are contained, the particles A may be contained in the same layer as the zirconium oxide particles or may be contained in different layers. It is particularly preferable from the viewpoint of dubbing property that (1) the zirconium oxide particles and the particles A are contained in at least the same outermost layer on one side, and the relationship between the film layer thickness t and the particle diameter d of the particles A is 0. .2d ≦ t ≦
10d, more preferably 0.5d ≦ t ≦ 5d, even more preferably 0.5d ≦ t ≦ 3d, or (2) the thickness t of the film layer containing the particle A and the particle size of the particle A. The relationship of d is 0.2d ≦ t ≦ 10d, more preferably 0.5d ≦ t ≦ 5d, still more preferably 0.5d ≦ t ≦.
3d, and a layer containing zirconium oxide particles was present as an outermost layer on the outer side thereof, and the outermost layer had a thickness of 0.
005 to 1 μm, more preferably 0.01 to 0.5 μm
m, and more preferably 0.02 to 0.3 μm.

The biaxially oriented film of the present invention has a number of projections of at least 2 × 2 × from the viewpoint of dubbing resistance and abrasion resistance.
It is preferably 10 ^{3 to} 5 × 10 ⁵ pieces / mm ² . The number of protrusions on at least one side is 3 × 10 ³ to 4 × 1
0 ⁵ pieces / mm ^{2 and} more preferably 5 × 10 ^{3 to} 3 × 10 ⁵
The number of pieces / mm ² .

Next, a method for producing the film of the present invention will be described.

Polyester containing zirconium oxide particles and, if necessary, other particles in a predetermined amount is dried, if necessary, then fed to a known extruder for melt lamination, and extruded in a sheet form from a slit die, An unstretched film is prepared by cooling and solidifying on a casting roll. That is, two or three extruders, two or three layers of manifolds or merging blocks are used to laminate the molten polyester using the molten blocks. In this case, the method of installing the static mixer and the gear pump in the polymer channel containing the agglomerated particles is effective for further improving the effect of the present invention.

Next, this unstretched film is biaxially stretched to be biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, a sequential secondary stretching method of first stretching in the longitudinal direction and then in the width direction is used, and stretching in the longitudinal direction is divided into three or more stages, with a longitudinal stretching temperature of 80 to 150 ° C. and a total longitudinal stretching ratio of 3.0. ~ 5.5
The double and longitudinal stretching speeds are preferably in the range of 5,000 to 50,000% / min. As a stretching method in the width direction, a method using a stenter is preferable, the stretching temperature is 80 to 160 ° C., the stretching ratio in the width direction is 3.5 to 6.5 times larger than the longitudinal ratio, and the stretching speed in the width direction is 1000 to 20000%. The range of / minute is preferred.

Next, this stretched film is heat-treated. The heat treatment temperature in this case is 170 to 200 ° C., especially 170 to 1
The range of 0.5 to 60 seconds at 90 ° C. is suitable.

[0030]

EXAMPLES The present invention will now be described in more detail with reference to examples. The physical properties in the examples were measured as follows.

(1) Evaluation of Average Particle Diameter of Particles A cross section of a film was cut with an ultrathin section having a thickness of 0.1 μm and observed with a transmission electron microscope at a magnification of 100,000 times or more,
Particle 1 for the smallest unit (primary particle) that cannot be divided
The area average diameter of 000 pieces (μm) was evaluated.

(2) Analysis of Crystal Structure of Zirconium Oxide Particles Analysis was carried out by X-ray diffraction measurement (wide-angle X-ray diffraction method). The X-ray generator used was RU-200B manufactured by Rigaku Denki Co., Ltd., and the X-ray source was CuKα rays. The goniometer is a 2155D type manufactured by Rigaku Denki Co., Ltd., and the counting and recording device is a RAD-B manufactured by Rigaku Denki Co., Ltd.
Used mold. The obtained diffraction pattern was analyzed using the JCPDS standard data as a reference to determine the crystal structure.

(3) Lamination Thickness of Laminated Film Using a secondary ion mass spectrometer (SIMS), an element and polyester derived from the highest concentration of particles in the film in the depth range of 3000 nm from the surface layer Using the concentration ratio (M ⁺ / C ⁻ ) of the carbon element as the particle concentration, the analysis in the thickness direction from the surface to a depth of 3000 nm is performed. In the surface layer, the particle concentration is low due to the interface of the surface, and the particle concentration increases as the distance from the surface increases. In the case of the film of the present invention, the particle concentration once reaching the maximum value starts to decrease again. Based on this concentration distribution curve, the depth at which the surface layer particle concentration becomes ½ of the maximum value (this depth is deeper than the maximum value) was determined and used as the laminated thickness. The conditions are as follows.

Measuring device Secondary ion quality analyzer (SIMS) Germany, ATOMIKA
A-DIDA 3000 measurement conditions Primary ion species O ₂ ⁺ Primary ion acceleration voltage 12 kV Primary ion current 200 nA Raster area 400 μm □ Analysis area Gate 30% Measurement vacuum 6.0 × 10 ^-9 Tool E-GUN 0. 5kV-3.0A

When the particles contained most in the depth range of 3000 nm from the surface layer are zirconium oxide particles, it is difficult to measure by SIMS. Therefore, while etching from the surface layer, XPS (X-ray photoelectron spectroscopy), IR (red Depth profile similar to the above may be measured by external spectroscopy) to determine the layer thickness, or the interface can be recognized from the difference in particle concentration and the difference in contrast due to the difference in polymer by cross-sectional observation with an electron microscope. The laminated thickness can also be determined. Further, after peeling the laminated polymer, the laminated thickness can be obtained by using a thin film step measuring device.

(4) Evaluation of surface irregularities According to JISB-0601, using a surfcom surface roughness meter, needle diameter 2 μm, load 70 mg, measurement reference length 0.25 m
The center line average roughness (Ra) was measured under the conditions of m and cutoff of 0.08 mm.

(5) Abrasion resistance (a) Abrasion resistance 1 A slit of tape having a film width of 1/2 inch was used to guide a guide pin (surface roughness: Ra 100 nm). ) Run on (running speed 10
00m / min, 15 passes, winding angle: 60 °,
Running tension: 60g). At this time, the scratches in the film are observed with a microscope, and scratches with a width of 2.5 μm or more are less than 2 per tape width in A grade, 2 or more and less than 3 in B grade, 3 or more in 1
Less than 0 was C grade, 10 or more was D grade, and B grade or higher was passed.

(B) Abrasion resistance 2 (repeated running) Using the same film and the same tester as in (a), after repeatedly running 100 times at a wrapping angle of 180 ° and a running speed of 3.3 cm / sec, the guide was used. White shavings (white powder) attached to the parts
Is visually determined. The evaluation criteria are as follows. Class A: The amount of white powder generated is very small. Class B: The amount of white powder generated is small. Class C: A large amount of white powder is generated. Class D: The amount of white powder generated is very large.

(6) Dubbing resistance The film is coated with a magnetic coating composition having the following composition by a gravure roll, magnetically oriented, and dried. In addition, a small test calendar device (steel roll / nylon roll,
(5 stages), temperature: 70 ° C., linear pressure: 200 kg / cm, and then calendaring is performed at 70 ° C. for 48 hours. The above tape raw material was slit to 1/2 inch to prepare a pancake. A length of 250 m from this pancake was incorporated into a VTR cassette to obtain a VTR cassette tape.

(Composition of magnetic coating) Co-containing iron oxide: 100 parts by weight Vinyl chloride / vinyl acetate copolymer: 10 parts by weight Polyurethane elastomer: 10 parts by weight Polyisocyanate: 5 parts by weight Lecithin: 1 part by weight Parts-methyl ethyl ketone: 75 parts by weight-methyl isobutyl ketone: 75 parts by weight-toluene: 75 parts by weight-carbon black: 2 parts by weight-lauric acid: 1.5 parts by weight

A 100% chroma signal was recorded on this tape by a television test waveform generator using a home VTR, and from the reproduced signal, a chroma S /
N was measured and designated as A. Also, after dubbing the master tape pancake on which the same signal is recorded as above to the same sample tape (unrecorded) pancake on which A was measured using a video software high-speed printing system (sprinter) of the magnetic field transfer method, The chroma S / N of the tape was measured in the same manner as above and designated as B. If the decrease in chroma S / N (A-B) due to this dubbing is less than 3 dB, the dubbing resistance is excellent,
The case of 3 dB or more and less than 5 dB was judged to be good, and the case of 5 dB or more was judged to be defective. Good is desirable, but good is practically usable.

Example 1 Zirconium oxide particles having a monoclinic crystal structure were dispersed in ethylene glycol, and the ethylene glycol slurry was polymerized with terephthalic acid to obtain master pellets of particle-containing polyethylene terephthalate. Further, similarly, polyethylene terephthalate master pellets containing calcium carbonate having an average particle diameter of 0.8 μm and polyethylene terephthalate master pellets containing no particles were obtained.

These polymers are mixed (polymer A: inorganic particles, zirconium oxide, calcium carbonate, polymer B:
Particle-free, calcium carbonate), and dried under reduced pressure (3 Torr) at 180 ° C. for 8 hours, and then extruder 1 and extruder 2 respectively.
Supply Polymer A and Polymer B to 285 ℃, 28
Melted at 0 ° C. After high-precision filtration of these polymers,
Three layers were laminated at the rectangular junction (lamination structure: polymer A /
Polymer B / Polymer A).

This was wound around a casting drum having a surface temperature of 25 ° C. by an electrostatically applied casting method and cooled and solidified to prepare an unstretched film. At this time, the ratio of the die slit gap / unstretched film thickness was set to 10. The total thickness and the thickness of the thermoplastic resin A layer were adjusted by adjusting the discharge rate of each extruder.

This unstretched film was stretched 3.5 times in the longitudinal direction at a temperature of 85 ° C. This stretching was performed in four stages with two sets of roll peripheral speed differences. This uniaxially stretched film was stretched 5.5 times in the width direction at 95 ° C. at a stretching rate of 2000% / min using a stenter and heat-treated at 190 ° C. for 3 seconds under a constant length to give a biaxial film having a total thickness of 15 μm. An oriented laminated film was obtained. The characteristics of this film are as shown in Table 1,
The abrasion resistance and dubbing resistance were good.

Examples 2 to 4, Comparative Examples 1 to 4 In the same manner as in Example 1, the kind of zirconium oxide particles,
Particle size, addition amount, and type of particles other than the particles, particle size,
Films with different addition amounts were obtained. As shown in Table 1, the film in the range of the present invention has good abrasion resistance and dubbing resistance, but those other than that cannot satisfy both abrasion resistance and dubbing resistance.

[0047]

[Table 1]

[0048]

According to the laminated polyester film of the present invention, since zirconium oxide particles having a specific crystal structure are used, it is excellent in abrasion resistance during repeated running, the surface of the film is not easily scratched, and it is used for magnetic recording media. In this case, excellent image quality can be obtained.

Claims (3)

[Claims] 1. A laminated polyester film, wherein monoclinic and / or tetragonal zirconium oxide particles are contained in at least one outermost layer of a laminated film having at least a two-layer structure. 2. A laminated polyester film, wherein monoclinic and / or tetragonal zirconium oxide particles are contained in at least one outermost layer of a laminated film having at least a three-layer structure. 3. The number of projections on at least one side is 2 × 10 ³ to
The laminated polyester film according to claim 1, which has a density of 5 × 10 ⁵ pieces / mm ² .