JP2812136B2 - Biaxially oriented laminated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a biaxially oriented laminated film.

[0002]

2. Description of the Related Art As a biaxially oriented laminated film, there is known a film composed of at least three or more layers and comprising a particle-containing layer having a projection-forming ability and a layer not containing particles having a projection-forming ability. (For example, Japanese Patent Application Laid-Open No. Hei 5-3185)
No. 9).

However, in the conventional biaxially oriented film described above, for example, a process of applying a magnetic layer for a magnetic medium, a calendering process, or a process of dubbing a produced video tape or the like to produce a soft tape or the like is required. With the increase, there was a disadvantage that the film surface was damaged by the contacting roll or guide. Also, in the conventional one,
To reduce the image quality during dubbing, the image quality when videotaped, that is, S / N (signal / noise ratio)
Also had the disadvantage of being insufficient. The present invention solves such a problem, and in particular, hardly damages a film in a high-speed process (hereinafter, referred to as excellent in scratch resistance), and furthermore, has less deterioration in image quality during dubbing (hereinafter, referred to as excellent in dubbing resistance).
An object is to provide a biaxially oriented laminated film.

[0004]

According to the present invention, there is provided a biaxially oriented laminated film comprising a layer B containing monodisperse particles having a particle size of 0.01 to 3 μm and an aggregated particle having a primary particle size of 5 to 100 nm. And a layer A containing at least a layer A containing the primary particle size d of the aggregated particles and the layer A
Is 0.1d ≦ t ≦ 50d, the particle diameter d1 of the monodisperse particles and the layer B containing the monodisperse particles.
Has a thickness t1 of 0.1d1 ≦ t1 ≦ 10d1.

The polymer constituting the biaxially oriented laminated film of the present invention is not particularly limited, but polyester is preferred from the viewpoint of scratch resistance and dubbing resistance. The polyester is not particularly limited, but ethylene terephthalate, ethylene α, β-bis (2-chlorophenoxy)
Ethane-4,4'-dicarboxylate, ethylene 2,
It is preferable to use at least one structural unit selected from 6-naphthalate units as a main component because scratch resistance and dubbing resistance are further improved. Above all,
Polyester containing ethylene terephthalate as a main component is particularly preferable because the dubbing resistance and the scratch resistance are further improved. In addition, two or more types of polyesters may be mixed or a copolymer may be used within a range not to impair the present invention.

The biaxially oriented laminated film of the present invention has a layer containing agglomerated particles and a layer containing monodisperse particles, and the polymer constituting either layer has a problem of scratch resistance and dubbing resistance. The above polymers are preferred. In addition, even when a layer containing no aggregated particles or monodispersed particles is provided, the above polymer is preferable from the viewpoint of scratch resistance and dubbing resistance.

The biaxially oriented layer film of the present invention has at least a two-layer structure of a layer B containing monodisperse particles and a layer A containing agglomerated particles. A layered film having at least a two-layer structure in which the layer B has no monodisperse particles or the layer A has no aggregated particles, or a monolayer film, cannot satisfy the dubbing resistance and the scratch resistance. The layer B may have a two-layer structure or more containing monodisperse particles in at least one layer, or a three-layer structure or more containing monodisperse particles on both sides of the layer C. Further, the layer A may be provided on both front and back surfaces.

[0008] The primary particle size of the aggregated particles contained in layer A of the biaxially oriented laminated film of the present invention is 5 to 100 nm, preferably 10 to 80 nm, more preferably 10 to 60 nm.
m. The secondary particle size is not particularly limited.
It is preferably from 0 to 800 nm, more preferably from 25 to 6 nm.
00 nm, more preferably 30 to 500 nm. If the primary particle size is outside the above range, both the scratch resistance and the dubbing resistance will not be good.

The content of the agglomerated particles is not particularly limited, but is preferably 0.01 to 3% by weight, more preferably 0.05 to 2% by weight, and even more preferably 0.1% by weight of the layer containing the agglomerated particles. １1% by weight.

The type of the aggregated particles is not particularly limited,
Zirconia, chain silica, alumina and the like are preferably used. Among them, zirconia, δ-alumina and θ-alumina have particularly good scratch resistance and dubbing resistance. Agglomerated particles should be different in type or primary diameter.
More than one kind may be used in combination. Further, in order to improve the adhesiveness between the aggregated particles and the polymer, the aggregated particles are provided with a sulfonic acid compound (a compound having a carboxyl group and a sulfonic acid group simultaneously in a chemical structure) and a phosphonic acid compound (a carboxyl group in the chemical structure). A compound having a phosphonic acid group simultaneously),
Surface treatment may be performed with a polyacrylic acid compound or the like.

The particle diameter of the monodispersed particles contained in the layer B of the biaxially oriented laminated film of the present invention is 0.01 to 3 μm, preferably 0.05 to 2 μm, more preferably 0.1 to 1 μm.
μm. If the particle size is outside the above range, both the scratch resistance and the dubbing resistance will not be good.

The content of the monodisperse particles is not particularly limited, but may be 0.01 to 10% by weight of the layer containing the monodisperse particles.
Is more preferably 0.05 to 8% by weight, more preferably 0.1 to 6% by weight.

The type of the monodispersed particles is not particularly limited, but is preferably at least one type selected from calcium carbonate particles, silica, organic particles, and titanium oxide, and in some cases, two or more types. Among them, calcium carbonate particles, silica and organic particles are preferred.

The crystal form of calcium carbonate is not particularly limited, but preferred examples thereof include a calcite type and a vaterite type. The organic particles are not particularly limited. However, divinylbenzene copolymer particles or silicone particles are preferable since scratch resistance and dubbing resistance are particularly improved. In the case of divinylbenzene copolymer particles, the degree of crosslinking is preferably 50% or more, more preferably 60% or more, and even more preferably 75% or more.
Here, the degree of crosslinking is the weight% of the crosslinkable composition in the organic particle composition. For example, a compound having two vinyl groups in one chemical structure (divinyl compound) acts as a crosslinking agent. The degree of crosslinking is the weight percent of the divinyl compound in the total composition.

The biaxially oriented film of the present invention comprises the above-mentioned polymer, agglomerated particles and monodisperse particles as main components. Other types of polymers may be blended as long as the object of the present invention is not impaired. Further, organic or 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 in which the above composition is biaxially oriented. A uniaxial or non-oriented film is not preferred because scratch resistance becomes poor. Although the degree of this orientation is not particularly limited, the scratch resistance is further improved 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. preferable. The Young's modulus, which is a measure of the degree of molecular orientation, is usually 1500 kg.
/ Mm ² is the manufacturing limit.

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

The relationship between the primary particle size d of the aggregated particles contained in the layer A and the layer thickness t of the layer A is 0.1 d ≦ t ≦ 50 d, preferably 0.2 d ≦ t ≦ 40 d, and more preferably 0.1 d ≦ t ≦ 40 d. 5d
≦ t ≦ 30d. If the relationship between the primary particle size of the aggregated particles and the thickness of the layer A is out of the above range, the scratch resistance and the dubbing resistance cannot be improved.

The relationship between the particle diameter d1 of the monodisperse particles and the thickness t1 of the layer B containing the monodisperse particles is 0.1d1 ≦
t1 ≦ 10d1, preferably 0.2d1 ≦ t1 ≦ 8d
1, more preferably 0.3d1 ≦ t1 ≦ 5d1. If the relationship between the particle size of the monodispersed particles and the thickness of the layer B is out of the above range, the scratch resistance and the dubbing resistance cannot be improved.

The thickness of the layer A of the biaxially oriented film of the present invention is not particularly limited, but is preferably from 5 to 500 nm, more preferably from 10 to 300 nm, from the viewpoint of scratch resistance and dubbing resistance. Preferably 10 to 200
nm. Further, the thickness of the layer B containing monodisperse particles of the biaxially oriented layered film of the present invention is not particularly limited. However, from the viewpoint of scratch resistance and dubbing resistance, the thickness is 0.01%.
To 5 μm, more preferably 0.05 to 3 μm.
m, more preferably 0.1 to 1 μm.

Further, the number of surface projections on the layer A side of the biaxially oriented layered film of the present invention is not particularly limited, but from the viewpoint of scratch resistance and dubbing resistance, 2.0 × 10 ³ to 1.
It is preferably 0 × 10 ⁷ / mm ² , more preferably 5.0 × 10 ^{3 to} 5.0 × 10 ⁶ / mm ² , and still more preferably 1.0 × 10 ^{4 to} 1.0 × 10 ⁶ / mm ² . mm ² .

Next, the method for producing the biaxially oriented laminated film of the present invention will be described.

First, as a method of causing the polyester to contain agglomerated particles or monodispersed particles, it is preferable to disperse in the form of a slurry in ethylene glycol, which is a diol component, and polymerize this ethylene glycol with a predetermined dicarboxylic acid component. Also, a method of directly mixing the water slurry of the particles with predetermined polyester pellets and kneading the polyester with a vent-type twin-screw extruder is very effective for further improving the effect of the present invention. .

As a method of adjusting the content of particles, a method of preparing a high-concentration master by the above method and diluting it with a polyester substantially free of particles at the time of forming a film to adjust the content of particles. Is valid.

Next, pellets containing a predetermined amount of particles are dried as necessary, then supplied to a known extruder for melt lamination, extruded from a slit die into a sheet, and cooled and solidified on a casting roll. To make an unstretched film. That is, two or three extruders, two or three
The molten polyester is laminated using a layer manifold or a merging block. In this case, a method of installing a static mixer and a gear pump in the polymer channel containing the aggregated particles and the monodispersed particles is effective for further improving the effect of the present invention.

Next, the unstretched film is biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, using a sequential biaxial stretching method in which stretching in the longitudinal direction and then in the width direction is performed first, the 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
And the longitudinal stretching speed is preferably in the range of 5,000 to 50,000% / min. As the 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 larger than the longitudinal ratio, 3.5 to 6.5 times, and the stretching speed in the width direction is 1000 to 20,000%. / Min is preferred.

Next, the stretched film is heat-treated. The heat treatment temperature in this case is 170 to 210 ° C., particularly 170 to 2 ° C.
The time at 00 ° C. is preferably in the range of 0.5 to 60 seconds.

[0028]

[Method for measuring physical properties and method for evaluating effects] The method for measuring characteristic values and the method for evaluating effects according to the present invention are as follows.

(1) Primary particle size, secondary particle size, average particle size of monodispersed particles of the aggregated particles The cross section of the film was measured by using a transmission electron microscope (TEM).
Observe at 000-100,000 times. The thickness of the section of the TEM is about 100 nm, and measurement is performed in 100 or more visual fields at different locations. The primary particle size of the agglomerated particles is the smallest unit of the indivisible particles of the agglomerated particles, the secondary particle size is the number average diameter of the equivalent circle equivalent diameter for the agglomerate, and the particle size of the monodisperse particles is the equivalent circle for the particles. It is the volume average diameter of the equivalent diameter.

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

(3) Lamination Thickness of Laminated Film Using a secondary ion mass spectrometer (SIMS), an element and polyester originating from the particles having the highest concentration among the particles in the film having a depth of 10 μm from the surface layer. The carbon element concentration ratio (M ⁺ / C ⁻ ) is defined as the particle concentration and the depth from the surface is 1
Analysis in the thickness direction is performed up to 0 μm. 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 which has once reached the maximum value starts to decrease again. Based on this concentration distribution curve, the depth at which the surface layer particle concentration was の of the local maximum value (this depth was deeper than the local maximum value) was determined, and this was defined as the lamination thickness. The conditions are as follows.

Measuring device Secondary ion mass spectrometer (SIMS) ATOMI, Germany
A-DIDA3000 manufactured by KA 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 When the particles most contained in the range from the surface layer to the depth of 10 μm are organic polymer particles, it is difficult to measure by SIMS. Therefore, XPS (X-ray photoelectron spectroscopy) is performed while etching from the surface layer. , IR (infrared spectroscopy) or the like may be used to measure the same depth profile as above to determine the lamination thickness.
The lamination thickness can also be determined by recognizing the interface from a change in particle concentration or a difference in contrast due to a difference in polymer by cross-sectional observation using an electron microscope or the like. Further, after the laminated polymer is peeled off, the laminated thickness can be determined using a thin film step measuring device.

(4) Molecular Orientation on Film Surface Using a sodium D line (589 nm) as a light source, the molecular orientation was measured using an Abbe refractometer. The measurement was performed at 25 ° C. and 65% RH using methylene iodide as the mounting solution. The biaxial orientation of the polymer is determined by setting the refractive index in the longitudinal, width, and thickness directions to N.
_1, when the N _2, N _3, 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 used as one criterion. Further, the refractive index may be measured using a laser refractometer. Further, when measurement is difficult by this method, a total reflection laser Raman method can be used. Measurement of laser total reflection Raman was performed by Raman manufactured by Jobin-Yvon.
The total reflection Raman spectrum was measured by the orU-1000 Raman system.
5cm ^-1 (skeleton vibration of benzene ring) and 1730cm
⁻¹ (stretching vibration of carbonyl group) Band intensity ratio of polarization measurement ratio (YY / XX ratio, etc. Here, YY: Raman light detection parallel to Y with laser polarization direction set to Y, 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 the polymer can be determined by converting the parameters obtained from the Raman measurement into the refractive index in the longitudinal direction and the width direction, and from the absolute value, difference, and the like. The total reflection Raman crystallization index of the surface was defined as the half-value width of 1730 cm ⁻¹ which is the stretching vibration of the carbonyl group. The measurement conditions in this case are as follows.

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

Detector PM: RCA31034 / Ph
oton Counting System (Hama
matsu C1230) (supply 1600
V) Measurement conditions 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,
Using an Instron type tensile tester, 25
It measured at 65 degreeC and 65% RH.

(6) Number of Surface Protrusions In a scanning electron microscope of a two-detector system, a measured value of the height of the projections when scanning with the height of the flat surface of the film surface set to 0 is sent to the image processing apparatus, and the image processing is performed. Reconstruct the film surface projection image on the device. Next, the highest value among the binarized individual projection portions is defined as the projection height, and this is obtained for each individual projection. This measurement was repeated 500 times in different places, and the height of 20 nm or more was defined as a protrusion, and the number of protrusions was determined. The magnification of the scanning electron microscope is
Select a value between 1000 and 100,000 times. In some cases, a high-precision optical interference type three-dimensional surface analyzer (WYKO)
The height information obtained using a TOPO-3D (manufactured by Sharp Corporation, objective lens: 40 to 200 times) may be read as the SEM value and used.

(7) Scratch Resistance A film obtained by slitting a film into a tape having a width of 1/2 inch is run on guide pins (surface roughness: 100 nm in Ra) using a tape running tester ( Travel speed 2
50 m / min, 1 pass of the number of runs, winding angle: 60 °, running tension: 90 g). At this time, the scratches in the film were observed with a microscope, and the number of scratches having a width of 1 μm or more per tape width was determined to be excellent when less than two, and when not less than two and less than ten were good, and when ten or more, the defects were poor. Although excellent is desirable, even good is practically usable. In the case of the film in which the layer A containing the aggregated particles was present, the surface was evaluated.

(8) Dubbing Resistance A magnetic paint having the following composition is applied to the film by a gravure roll, magnetically oriented, and dried. In addition, a small test calendar device (steel roll / nylon roll,
After performing a calendering process at a temperature of 70 ° C. and a linear pressure of 200 kg / cm, curing is performed at 70 ° C. for 48 hours. The raw tape was slit into 1/2 inch to prepare a pancake. A length of 250 m from this pancake was incorporated into a VTR cassette to form 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 the reproduced signal was subjected to chroma S / S with a color video noise measuring instrument.
N was measured and set to A. After dubbing the pancake of the master tape on which the same signal as described above was recorded to the pancake of the same sample tape (unrecorded) as in the measurement of A using a magnetic field transfer type video software high-speed printing system (sprinter) The chroma S / N of the tape was measured in the same manner as described above, and was designated as B. Chroma S / N by this dubbing
When the decrease (AB) is less than 3 dB, the anti-dubbing property:
Excellent, when it was 3 dB or more and less than 5 dB, it was judged as good, and when 5 dB or more, it was judged as bad. Although excellent is desirable, even good is practically usable. For the film having the layer A containing the aggregated particles on only one side, the opposite side of the layer A was evaluated.

[0042]

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

Example 1 Zirconia (agglomerated particles) having a primary particle size of 40 nm was dispersed in ethylene glycol, and this ethylene glycol slurry was polymerized with terephthalic acid to obtain aggregated particle-containing polyethylene terephthalate pellets. In addition, particle size 0.8μ
m of calcium carbonate was dispersed in ethylene glycol, and the ethylene glycol slurry was polymerized with terephthalic acid to obtain polyethylene terephthalate pellets containing monodispersed particles. Further, a polyethylene terephthalate pellet containing no particles was obtained.

These polymers (polymer A: polymer containing zirconia particles, polymer B: polymer containing calcium carbonate particles, and polymer C: no particles) were dried at 180 ° C. for 8 hours under reduced pressure (3 Torr), and then extruder 1 Machine 2,
It was supplied to the extruder 3 and melted at 285 ° C, 280 ° C and 280 ° C. After each of these polymers was filtered with high precision, they were laminated at a merging ratio of 0.1 / 1/12/1 / 0.1 at a rectangular merging portion to form a five-layer lamination (A / B / C / B / A). ).

This was wound around a casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method, and cooled and solidified to produce an unstretched film. At this time, the ratio of die slit gap / unstretched film thickness was set to 10. Further, the discharge amount of each extruder was adjusted to adjust the layer A, the layer B, the layer C, and the total thickness.

This unstretched film was stretched 3.5 times in the longitudinal direction at a temperature of 90 ° C. This stretching was performed in four stages with a difference in peripheral speed between two sets of rolls. This uniaxially stretched film is stretched at a stretching speed of 2000% / min using a tenter at 105 ° C.
Then, the film was stretched 5.4 times in the width direction and heat-treated at 200 ° C. for 5 seconds under a constant length to obtain a biaxially oriented laminated film having a total thickness of 14.2 μm. The characteristics of this film are as shown in Table 1, and the scratch resistance and the dubbing resistance were good.

Example 2 to Example 6, Comparative Example 1, Comparative Example 2 In the same manner as in Example 1, the type of agglomerated particles, the primary particle size, the type of the monodispersed particles, the particle size, the thickness of each layer, etc. Was obtained. As shown in Tables 1 and 2, the films in the range of the present invention have good scratch resistance and dubbing resistance, but if they are not, they cannot achieve both scratch resistance and dubbing resistance.

[0048]

[Table 1]

[Table 2]

[0049]

According to the biaxially oriented film of the present invention, the agglomerated particles and the monodisperse particles are contained in different layers, and the thickness of each layer is within a specific range. The film surface of the layer A surface is hardly damaged, and particularly, when the layer A containing the aggregated particles is only one side, the magnetic layer is applied to the opposite surface to the layer A containing the aggregated particles,
When used for a magnetic medium, excellent image quality and dropout characteristics can be obtained.

Continuation of the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B32B 1/00-35/20 G11B 5/704 B29C 55/00-55/30

Claims (6)

(57) [Claims] 1. A biaxially oriented laminated film comprising at least a layer B containing monodisperse particles having a particle size of 0.01 to 3 μm and a layer A containing aggregated particles having a primary particle size of 5 to 100 nm. The primary particle size d of the particles and the thickness t of the layer A are 0.1d ≦ t ≦ 50d, the particle size d1 of the monodisperse particles and the layer B containing the monodisperse particles
Wherein the thickness t1 of the biaxially oriented laminated film is 0.1d1 ≦ t1 ≦ 10d1. 2. The biaxially oriented laminated film according to claim 1, wherein the layer A and the layer B are adjacent to each other. 3. The biaxially oriented laminated film according to claim 1, wherein a layer B is laminated on both sides of the layer C, and at least one layer B is adjacent to the layer A. 4. The biaxially oriented laminated film according to claim 1, wherein the layer A is provided on both sides. 5. The aggregated particles are zirconia, δ-alumina,
Claim 1 characterized by being selected from θ-alumina
The biaxially oriented laminated film according to claim 4. 6. The monodisperse particles comprising calcium carbonate, silica,
The biaxially oriented laminated film according to any one of claims 1 to 5, which is selected from organic particles.