JPH06298953A - Biaxially oriented film - Google Patents

Abstract

(57) [Summary] [Structure] A phosphon compound having simultaneously a carboxyl group and a phosphonic acid group in its chemical structure, and a primary particle size of 5 to 100.
A biaxially oriented film, which contains agglomerated particles of nm. [Effect] Since a compound with a specific chemical structure and agglomerated particles are used, the loss of agglomerated particles is reduced, the film surface is less likely to be scratched, and excellent image quality and dropout characteristics are obtained when used for magnetic media. You can

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a biaxially oriented film.

[0002]

2. Description of the Related Art As a biaxially oriented film, for example, a biaxially oriented polyester film, a film in which agglomerated particles are contained in polyester is known (for example, JP-A-3-
6239).

[0003]

However, in the above-mentioned conventional biaxially oriented film, for example, a soft tape or the like is manufactured by applying a magnetic layer in a magnetic medium application, a calendering step, or by dubbing the resulting video tape or the like. There has been a drawback in that the film surface is scratched by the contacting rolls or guides with the increase in the process speed of the process. Further, the conventional one has a drawback that the image quality when formed into a video tape, that is, the S / N (signal / noise ratio) is insufficient because of the deterioration of the image quality during the dubbing. The present invention solves such a problem, and in particular, a biaxially oriented film in which a film is less likely to be scratched in a high-speed process (hereinafter referred to as excellent in scratch resistance) and has little deterioration in image quality during dubbing (hereinafter referred to as excellent in dubbing resistance) The purpose is to provide.

[0004]

The biaxially oriented film of the present invention for this purpose comprises a phosphon compound having a carboxyl group and a phosphonic acid group at the same time in its chemical structure, and agglomerated particles having a primary particle size of 5 to 100 nm. It is characterized by containing.

The polymer constituting the biaxially oriented film of the present invention is not particularly limited, but polyester is preferable. The polyester is not particularly limited, but at least one selected from ethylene terephthalate, ethylene α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate, and ethylene 2,6-naphthalate unit.
It is preferable to use various kinds of structural units as main constituents because scratch resistance and dubbing resistance are further improved. Of these, polyesters containing ethylene terephthalate as a main constituent component are particularly preferable because the dubbing resistance and scratch resistance are further improved. Two or more kinds of polyesters may be mixed, or a copolymerized polymer may be used, as long as the present invention is not impaired.

The biaxially oriented film of the present invention contains at least one kind of aggregated particles. Depending on the case, you may contain 2 or more types of aggregated particles. If the agglomerated particles are not contained, scratch resistance deteriorates.

The primary particle size of the agglomerated particles is 5 to 100 nm, preferably 10 to 80 nm, more preferably 10 to 60 nm.
nm. If the primary particle diameter is out of the above range, both scratch resistance and dubbing resistance are not good. Also,
The agglomerated secondary particle size is not particularly limited, but scratch resistance,
From the viewpoint of dubbing resistance, 20-800 nm, and further 25-
It is preferably 600 nm, and more preferably 30 to 500 nm.

Although the content of the agglomerated particles is not particularly limited,
0.01 to 3% by weight, preferably 0.05 to 2% by weight,
Scratch resistance and dubbing resistance are particularly good when the content is more preferably 0.1 to 1% by weight.

The type of aggregated particles is not particularly limited,
Zirconia, silica, alumina and the like are preferably used. Among them, zirconia, δ-alumina, θ-alumina and γ-alumina have particularly good scratch resistance and dubbing resistance. Two or more types of aggregated particles having different types or different primary particle sizes may be used in combination.

Further, in the present invention, in addition to the agglomerated particles,
It is necessary to contain a compound having both a carboxyl group and a phosphonic acid group in its chemical structure. By containing this compound, the adhesiveness between the polymer and the agglomerated particles is improved, the falling of particles is reduced, and the scratch resistance and dubbing resistance are improved. Therefore, the compound having both a carboxyl group and a phosphonic acid group in the chemical structure may be used alone in the polymer, but it is more preferable to use the aggregated particles in the surface-treated state.

The chemical structure of the phosphon compound having a carboxyl group and a phosphonic acid group at the same time in the chemical structure is not particularly limited, but compounds represented by the following formulas are preferable examples.

(HO) ₂ P (O) -R-COOH Here, R is an alkyl group having 1 to about 10 carbon atoms, which may have an unsaturated bond, and may be chain-like or branched. Good.
Further, it may have an aromatic, that is, a benzene ring. As a preferable structure, a compound represented by the following formula is exemplified.

(HO) ₂ P (O) CH ₂ CH ₂ COOH In the biaxially oriented film of the present invention, from the viewpoint of scratch resistance and dubbing resistance, in addition to the above-mentioned at least one kind of agglomerated particles, It preferably contains non-aggregated particles. The non-aggregated monodisperse particles include, but are not particularly limited to, at least one kind selected from calcium carbonate particles, crosslinked organic particles, colloidal silica particles, and titanium oxide particles, and in some cases, two or more kinds of particles. It is preferable. In that case, a preferable combination includes calcium carbonate particles and cross-linked organic particles.

The crystal form of the calcium carbonate particles is as follows:
Although not particularly limited, calcite type, vaterite type and the like are exemplified. The crosslinked organic particles are not particularly limited, but in the case of divinylbenzene copolymer particles having a degree of crosslinking of 50% or more, preferably 60% or more, more preferably 75% or more, scratch resistance and dubbing resistance are particularly high. It is preferable because it becomes good.

The particle size of the monodisperse particles is not particularly limited, but the average particle size is 0.1 to 2 μm, preferably 0.1.
It is 2 to 1.5 μm, more preferably 0.3 to 1 μm. The content of the monodisperse particles is not particularly limited, but the scratch resistance is 0.01 to 10% by weight, preferably 0.05 to 8% by weight, more preferably 0.1 to 6% by weight, Dubbing resistance becomes particularly good.

The biaxially oriented film of the present invention comprises the above-mentioned polymer, agglomerated particles and a phosphon compound as main components, but may be blended with other polymers within a range not impairing the object of the present invention. Organic and inorganic additives such as antioxidants, heat stabilizers, lubricants, and ultraviolet absorbers may be added to the extent that they are usually added.

The biaxially oriented film of the present invention is a film obtained by biaxially orienting the above composition. A uniaxial or non-oriented film is not preferable because scratch resistance becomes poor. The degree of this orientation is not particularly limited, but especially when the Young's modulus, which is a measure of the degree of molecular orientation of the polymer, is 350 kg / mm ² or more in both the longitudinal direction and the width direction, scratch resistance is further improved. preferable. Young's modulus, which is a measure of the degree of molecular orientation, is usually 1500 kg.
/ Mm ² is a manufacturing limit.

Further, in the film of the present invention, even if the Young's modulus is within the above range, a part of the film in the thickness direction, for example, the polymer molecules near the surface layer are not oriented or uniaxially oriented, that is, When the molecular orientation of the entire portion in the thickness direction is biaxial orientation, scratch resistance and dubbing resistance are further improved. Especially scratch resistance and dubbing resistance are better when the molecular orientation measured by Abbe refractometer, laser refractometer, total reflection laser Raman method, etc. is biaxial orientation on both front and back surfaces. Becomes

In the biaxially oriented film of the present invention, from the viewpoint of scratch resistance and dubbing resistance, the film containing the agglomerated particles and the phosphon compound is one outermost layer of a laminated film having at least a two-layer structure. It is preferable. In addition, when the biaxially oriented film of the present invention has a structure of three or more layers, from the viewpoint of scratch resistance and dubbing resistance, the film containing the agglomerated particles and the phosphon compound has a three-layer structure. It is preferable to be one outermost layer of In that case, the thickness of the film layer containing agglomerated particles is not particularly limited, but from the viewpoint of scratch resistance and dubbing resistance, it is 0.005 to 3 μm, preferably 0.01 to 2 μm, and more preferably 0. 02 ~
It is 1 μm.

Further, the monodisperse particles other than the agglomerated particles may be contained in the same layer as the agglomerated particles or may be contained in a different layer, but in terms of scratch resistance and dubbing resistance. It is particularly preferable that the agglomerated particles and the monodisperse particles are contained in the same outermost surface layer on at least one surface side, and the relationship between the film layer thickness t and the particle diameter d of the monodisperse particles
0.2d ≦ t ≦ 10d, preferably 0.5d ≦ t ≦ 5
d, more preferably 0.5d ≦ t ≦ 3d, or the relationship between the thickness t of the film layer containing the monodisperse particles and the particle diameter d of the monodisperse particles is 0.2d ≦ t ≦ 10d, Preferably 0.5d ≦ t ≦ 5d, more preferably 0.5d
≦ t ≦ 3d, a layer containing agglomerated particles is present as the outermost layer on the outer side, and the thickness of the outermost layer is 0.005
˜1 μm, preferably 0.01 to 0.5 μm, and more preferably 0.02 to 0.3 μm.

The polymer constituting the layers other than the film layer containing the aggregated particles and the phosphon compound in the laminated structure is not particularly limited, but polyester is preferable. The polyester is not particularly limited, but ethylene terephthalate, ethylene α, β-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylate, ethylene 2,6
-When at least one structural unit selected from naphthalate units is the main constituent component, scratch resistance and dubbing resistance are better, which is preferable. Of these, polyesters containing ethylene terephthalate as a main constituent component are particularly preferable because the dubbing resistance and scratch resistance are further improved.

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

Next, the method for producing the film of the present invention will be described in the case of a laminated polyester film.

First, the agglomerated particles and the phosphon compound are mixed and then dispersed in an ethylene glycol slurry. Then, this ethylene glycol is polymerized with a predetermined dicarboxylic acid component. Further, a method of directly kneading the particle slurry into a predetermined polyester by using a vent type twin-screw kneading extruder is also very effective in further improving the effect of the present invention.

As a method for controlling the content of particles, it is effective to prepare a high-concentration master by the above method and dilute it with a polyester which does not substantially contain particles at the time of film formation.

Next, pellets containing a predetermined amount of particles are dried, if necessary, and then supplied to a known extruder for melt lamination, extruded into a sheet form from a slit die, and cooled and solidified on a casting roll. To make an unstretched film. Ie 2 or 3 extruders, 2 or 3
Laminated polyester in the melt is laminated using a manifold or confluence block of layers. 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 and biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, a sequential biaxial 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, the longitudinal stretching temperature is 80 to 150 ° C., and the total longitudinal stretching ratio is 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.

[0029]

[Physical property measuring method and effect evaluating method] The characteristic value measuring method and effect evaluating method of the present invention are as follows.

(1) Primary particle size of agglomerated particles, secondary particle size of agglomerated particles, average particle size of monodisperse particles The cross section of the film was measured by using a transmission electron microscope (TEM).
Observe at a magnification of 0,000 times or more. Section thickness of TEM is about 1
It is set to 00 nm, and the location is changed to measure 100 fields or more.
The primary particle size of the agglomerated particles is the average value of equivalent circle equivalent diameters of the smallest unit of the agglomerated particles that cannot be divided, the secondary particle size of the agglomerates, and the particle size of the monodisperse particles of the monodisperse particles. .

(2) Content of Particles A solvent in which the polyester is dissolved but not the particles is selected is selected, the particles are centrifuged from the polyester, and the ratio (% by weight) to the total weight of the particles is taken as the particle content.
In some cases, the combined use of infrared spectroscopy is also effective.

(3) Degree of cross-linking of cross-linked particles It is represented by the weight percentage of the cross-linking component with respect to the total weight of the monomer.

(4) Molecular orientation of film surface The measurement was carried out using an Abbe refractometer with sodium D line (589 nm) as a light source. Methylene iodide was used as the mount solution, and measurement was performed at 25 ° C. and 65% RH. The biaxial orientation of a polymer has a refractive index of N in the longitudinal direction, the width direction, and the thickness direction.
_{When 1} , N ₂ and N ₃ are used, the absolute value of (N ₁ −N ₂ ) is 0.07 or less, and N ₃ / [(N ₁ + N ₂ ) / 2] is 0.95 or less. Can be a standard. Further, the refractive index may be measured using a laser type refractometer. Further, when the measurement is difficult by this method, the total reflection laser Raman method can be used. Laser total reflection Raman is measured by Jobin-Yvon Raman.
OrU-1000 Raman system measures the total reflection Raman spectrum, for example, in the case of PET, 161
5 cm ^-1 (skeleton vibration of benzene ring) and 1730 cm
Polarization measurement ratio of band intensity ratio of ^-1 (stretching vibration of carbonyl group) (YY / XX ratio, etc. where YY: Raman light detection parallel to Y with X as the laser polarization direction, X
X: Raman light detection parallel to X, where X is the polarization direction of the laser, corresponds to the molecular orientation.
The biaxial orientation of a polymer can be determined by converting the parameters obtained from Raman measurement into the refractive index in the longitudinal direction and the refractive index in the width direction, and the absolute value or difference thereof. Further, the half-value width of 1730 cm ^-1 , which is the stretching vibration of the carbonyl group, was used as the total reflection Raman crystallization index of the surface. The measurement conditions in this case are as follows.

Light source Argon ion laser (514
5A) Setting of sample The surface of the film was pressed against a total reflection prism, and the incident angle of the laser on the prism (angle with the film thickness direction) was set to 60 °.

Detector PM: RCA31034 / Ph
oton Counting System (Hama
matsu C1230) (supply 1600)
V) Measurement condition SLIT 1000 μm LASER 100 mW GATE TIME 1.0 sec SCAN SPEED 12 cm ⁻¹ / min SAMPLING INTERVAL 0.2 cm
^-1 REPEAT TIME 6

(5) Young's modulus According to the method specified in JIS-Z-1702,
25 using an Instron type tensile tester
It was measured at 65 ° C. and 65% RH.

(6) Lamination Thickness of Laminated Film Using a secondary ion mass spectrometer (SIMS), an element derived from the highest concentration of particles in the film in the depth range of 3000 nm from the surface layer and the polyester The concentration ratio (M ⁺ / C ⁻ ) of the carbon element is used as the particle concentration, and analysis is performed in the thickness direction from the surface to a depth of 3000 nm. 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 surface particle concentration is 1 / maximum
A depth of 2 (the depth is deeper than the maximum value) was obtained and used as the laminated thickness. The conditions are as follows.

Measuring Device Secondary Ion Mass Spectrometer (SIMS) ATOMI, Germany
KA Co. A-DIDA3000 Measurement conditions Primary ion species 0 ₂ ⁺ Primary ion acceleration voltage 12 kV Primary ion current 200 nA Raster area 400 μm □ Analysis area Gate 30% Measurement vacuum degree 6.0 × 10 ⁻⁹ Torr E-GUN 0 .5 kV-3.0 A If the particles contained most in the depth range of 3000 nm from the surface layer are organic polymer particles, it is difficult to measure by SIMS, so XPS (X
It is also possible to measure the depth profile in the same way as above by using line photoelectron spectroscopy), IR (infrared spectroscopy), etc., and determine the stack thickness. Also, by observing the cross section with an electron microscope, etc., changes in particle concentration and differences in polymers. It is also possible to recognize the interface from the difference in contrast due to and obtain the laminated thickness. Furthermore, after peeling the laminated polymer, the laminated thickness can be obtained using a thin film step measuring machine.

(7) Scratch resistance A film slit into a tape having a width of 1/2 inch is run on a guide pin (surface roughness: Ra of 100 nm) using a tape running tester ( Traveling speed 2
50m / min, 1 pass, wrapping angle: 60 °, running tension: 90g). At this time, the scratches in the film were observed with a microscope, and it was judged that scratches having a width of 1 μm or more per tape width were less than 2 and excellent, 2 or more and less than 10 were good, and 10 or more were defective. Good is desirable, but good is practically usable.

(8) Dubbing resistance A magnetic coating composition having the following composition is applied to a film 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 paint) 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 a chroma S /
N was measured and designated as A. After dubbing the pancake of the master tape recording the same signal as above to the pancake of the same sample tape (unrecorded) where A was measured using the 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. Chroma S / N by this dubbing
When the decrease (AB) was less than 3 dB, the dubbing resistance was excellent, and when 3 dB or more and less than 5 dB, it was judged as good and 5 dB or more was judged as poor. Good is desirable, but good is practically usable.

[0043]

EXAMPLES Next, the embodiments of the present invention will be explained based on examples.

Example 1 First, zirconia (aggregated particles) and 2-carboxyethylphosphonic acid were mixed and dispersed in ethylene glycol, and this ethylene glycol slurry was polymerized with terephthalic acid.
A master pellet of polyethylene terephthalate containing aggregated particles was prepared. Further, in the same manner, polyethylene terephthalate master pellets containing calcium carbonate and polyethylene terephthalate master pellets containing no particles were obtained.

These polymers were mixed in appropriate amounts (polymer A: particle-free, zirconia, 2-carboxyethylphosphonic acid, calcium carbonate, polymer B: particle-free, calcium carbonate), and dried under reduced pressure at 180 ° C. for 8 hours (3 Torr). After that, it is supplied to the extruder 1 and the extruder 2, respectively, at 282 ° C. and 2
Melted at 80 ° C. After high-precision filtration of these polymers, three layers were laminated at the rectangular junction (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. In addition, the total amount of thermoplastic resin A
The layer thickness was adjusted.

This unstretched film was stretched at a temperature of 85 ° C. in the longitudinal direction by a factor of 3.4. This stretching was carried out in four stages with the difference in peripheral speed between each pair of rolls. This uniaxially stretched film was stretched 5.2 times in the width direction at 95 ° C. at a stretching speed of 2000% / min using a stenter, and then heat-treated at 190 ° C. for 3 seconds under a constant length, and biaxially oriented with a total thickness of 15 μm. A laminated film was obtained. The characteristics of this film are as shown in Table 1,
The scratch resistance and dubbing resistance were good.

Examples 2 to 4, Comparative Examples 1 to 4 In the same manner as in Example 1, agglomerated particles and a phosphon compound-containing film were obtained. As shown in Table 1, the films in the scope of the present invention have good scratch resistance and dubbing resistance, but those other than those cannot satisfy both scratch resistance and dubbing resistance.

[0049]

[Table 1]

[0050]

According to the biaxially oriented film of the present invention, since a phosphon compound having a carboxyl group and a phosphonic acid group at the same time in its chemical structure and agglomerated particles are used, the film surface is not easily scratched and the magnetic medium When used, excellent image quality and dropout characteristics can be obtained.

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // B29K 105: 16 B29L 7:00 4F

Claims (7)

[Claims] 1. A phosphon compound having a carboxyl group and a phosphonic acid group at the same time in its chemical structure and having a primary particle size of 5 to 5.
A biaxially oriented film, which contains aggregated particles of 100 nm. 2. The biaxially oriented film according to claim 1, further comprising monodisperse particles having a particle size of 0.1 to 2 μm, in addition to the phosphon compound and the agglomerated particles. 3. The biaxially oriented film according to claim 1, wherein the film containing a phosphon compound and agglomerated particles is one outermost layer of a laminated film having at least a two-layer structure. . 4. The film according to claim 1, wherein the film containing a phosphon compound and agglomerated particles is one outermost layer of a laminated film having at least a three-layer structure. Axial oriented film. 5. The biaxially oriented film according to claim 1, wherein the aggregated particles are at least one kind selected from zirconia, alumina and silica. 6. The biaxially oriented film according to claim 2, wherein the monodisperse particles are at least one selected from calcium carbonate particles, crosslinked organic particles, colloidal silica particles, and titanium oxide particles. 7. The biaxially oriented film according to any one of claims 1 to 7, wherein the phosphon compound is represented by the following formula. (HO) ₂ P (O) CH ₂ CH ₂ COOH