JP3238589B2 - Biaxially oriented 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 biaxially oriented laminated polyester film, and more particularly, to at least one surface layer having uniform surface roughness, slip resistance, abrasion resistance, scratch resistance and the like in the width direction. The present invention relates to a biaxially oriented laminated polyester film.

[0002]

2. Description of the Related Art Biaxially oriented polyester films are used in many applications such as magnetic tapes, electrical applications, photographic applications, metallizing applications and packaging applications because of their excellent properties. In particular, because of its high strength and elastic modulus, it is widely used as a base film for magnetic recording media, for example, video tapes, audio tapes, computer tapes, floppy disks, and the like.

[0003] In recent years, these fields of application have increased the recording density,
There is an increasing demand for higher quality, and accordingly, there is an increasing demand for a polyester film as a base to have a flat surface.

However, when the film surface is flat, the coefficient of friction of the film becomes high in, for example, a magnetic tape application, causing problems such as running failure and scratching. Also, if the film surface becomes flat, the film roll in the process of winding the film into a roll during film production will be significantly deteriorated, making it difficult to obtain a film roll with a good roll shape, and in addition, increasing productivity. As a result, it is necessary to increase the film winding speed and increase the width. However, with the increase in speed and width, there is a problem that it is difficult to obtain a film roll having an even better winding shape.

[0005] As described above, it is necessary to simultaneously solve the problems caused by the planarization of the film surface.

Therefore, a laminated film having different front and back surfaces with different surface roughness of the film surface, that is, a front and back different area layer film in which one surface (front surface) is flat and the other surface (back surface) is rough has been proposed. I have. This film is effective when the required flatness is only on one side of the film and the other side may be rough. For example, in the case of a base film of a magnetic tape, if a magnetic layer is provided on the surface of the film and the rough surface is used as the running surface, the film is slippery from the viewpoint of improving the electromagnetic conversion characteristics in terms of flatness and running characteristics of the film. This makes it possible to obtain a better base film for magnetic tape. However, in recent years, the base film has been required to be flatter than the surface roughness of the roughened surface, and the base film has been increasingly flattened.

Under these circumstances, variations in film surface roughness become apparent as differences in film characteristics, and in particular, variations in surface roughness in the film width direction cause differences in ease of winding. Is coming.

For example, in the production of magnetic tape, which is one of the main uses of polyester films, a long polyester film having a wide width (for example, 300 to 1500 mm width) is subjected to a treatment such as coating a magnetic layer and calendering. After obtaining a wide web, for example, 8mm, slit into a tape width such as 1/2 inch, tens of tapes are simultaneously wound into a length of several thousand meters to several hundred meters to form a pancake, At that time, if there is a difference in the surface roughness in the width direction of the base wide polyester film, a slit tape having a different surface roughness can be obtained. And when the slit product is wound up under the conditions that match the surface roughness of the flat part,
Since the base surface of the rough slit product is more slippery (excellent in running property) than the flat base product of the slit product, the end surface of the rough slit product (pancake) tends to shift, resulting in winding Appearance becomes bad, and product yield decreases. Furthermore, when the end face shift is remarkable, the pancake is broken on the way, and the process must be stopped. On the other hand, if winding is performed under conditions that match the surface roughness of the rough part, the slit product in the rough part can be wound neatly, but the slit product in the flat part is less slippery (runnability) than the rough part. (Hump-like projections) occur, or the winding shape deteriorates (the winding does not become a clean circular shape, but becomes partially square). Lower it.

If the surface roughness differs in the width direction of the wide film as described above, it becomes difficult to obtain the same good winding shape in all the slit products as described above.

[0010]

The present inventor has studied the variation of the surface roughness in the film width direction. As a result, when the film surface roughness is laterally stretched by the tenter method, the lubricant is uniformly dispersed in the film. It has been found that even if it is contained, it tends to be flatter as it is closer to the side end compared to the center of the tenter. The reason is considered as follows.

[0011] Polyester films are generally manufactured by a sequential biaxial stretching method, and are made to have a vertical-horizontal, vertical-horizontal-
It is stretched and manufactured in multiple stages such as vertical, vertical-horizontal-vertical-horizontal, horizontal-vertical, vertical-vertical-horizontal, etc. In these processes,
The transverse stretching step is usually performed by a tenter method. The tenter method is a method in which a film is guided to a tenter and both ends are gripped with a clip-like material, and the clips at both ends are laterally stretched during transport to thereby stretch the film to a predetermined magnification.

In this tenter method, during the transverse stretching, a contraction stress acts on the film to be conveyed in the longitudinal direction in accordance with the transverse stretching. However, both ends held by the clip and the center where the restraining force by the clip is relatively weak. There is a difference in the action of the shrinkage stress between the part and the part, and the way of molecular orientation progresses. This phenomenon is called Boeing, but compared to both ends,
This is because the center part is delayed with respect to the tenter flow direction. This is because if you draw a horizontal line on the surface of the film before entering the tenter, this straight line will be deformed in the tenter and become a concave line on the film that has left the tenter. I understand. It is considered that the difference in how the molecular orientation progresses due to the bowing causes a difference in surface properties and other characteristics in the tenter width direction.

The present inventor further studied to reduce or eliminate the fluctuation of the surface characteristics in the film width direction.
When the layer thickness of the surface layer changes in the laminated film, the surface roughness of the surface layer of the same lubricant composition changes with the change, and this phenomenon is considered as the vertical and horizontal refractive index. When applied in proportion to the difference or the orientation angle,
The present inventors have found that fluctuations in surface roughness in the film width direction can be reduced, and have reached the present invention.

[0014]

That SUMMARY OF THE INVENTION The present invention is co
A laminated polyester film formed by extrusion.
I, at least the thickness of one surface layer changes along less and the film width direction 3μm or 0.02 [mu] m, and a surface roughness Ra of the surface layer of a and in the film width direction 3~40nm A biaxially oriented laminated polyester film having a variation of 5% / 500 mm or less.

The polyester in the present invention is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component. Such polyesters are substantially linear and have film forming properties, especially film forming by melt molding. Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid, isophthalic acid, diphenoxyethane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenyl sulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, and anthracene dicarboxylic acid. Can be. As the aliphatic glycol, for example, a polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol or the like, or an alicyclic group such as cyclohexanedimethanol. Diols and the like can be mentioned.

In the present invention, a polyester containing alkylene terephthalate and / or alkylene naphthalate as a main component is preferably used.

Among such polyesters, in particular, polyethylene terephthalate and polyethylene-2,6-naphthalate, for example, 80% by mole or more of the total dicarboxylic acid component contains terephthalic acid and / or 2,6-
Naphthalenedicarboxylic acid, 8 of all glycol components
A copolymer in which 0 mol% or more is ethylene glycol is preferred. In this case, not more than 20 mol% of the total acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and also aliphatic dicarboxylic acids such as adipic acid and sebacic acid. An alicyclic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid; Further, 20 mol% or less of the total glycol component can be the above-mentioned glycols other than ethylene glycol. For example, aromatic diols such as hydroquinone, resorcinol and 2,2-bis (4-hydroxyphenyl) propane; , 4-
Aliphatic diols having an aromatic ring such as dihydroxydimethylbenzene; polyalkylene glycols (polyoxyalkylene glycols) such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol can also be used.

Further, the polyester in the present invention includes:
For example, aromatic oxyacids such as hydroxybenzoic acid, ω-
Also included are those which copolymerize or combine a component derived from an oxycarboxylic acid such as an aliphatic oxyacid such as hydroxycaproic acid at 20 mol% or less based on the total amount of the dicarboxylic acid component and the oxycarboxylic acid component.

Further, the polyester in the present invention includes:
An amount in the range that is substantially linear, for example, 2 for the total acid component
Also included are those obtained by copolymerizing a polycarboxylic acid or polyhydroxy compound having a functionality of 3 or more, such as trimellitic acid or pentaerythritol, in an amount of not more than mol%.

The above polyesters are known per se and can be produced by a method known per se.

In the present invention, the biaxially oriented laminated polyester film is composed of at least two layers, but may have three or more layers as long as the object of the present invention is not impaired.
The polyester in each layer may be the same or different.

The biaxially oriented laminated polyester film of the present invention has at least one surface layer having a surface roughness Ra of 3
４０40 nm. If the surface roughness Ra is too small,
When the film is wound up on a roll, bumps (bulges) are likely to occur even if the winding conditions are adjusted.
If it is larger than nm, the end face is likely to be misaligned when wound up on a roll, which is not preferable. From these points, the surface roughness Ra is preferably 4 nm or more, more preferably 5 nm or more, and 35 nm or less, and more preferably 25 nm or less.
The thickness is particularly preferably 15 nm or less.

The surface layer contains one or more inert particles (lubricants). In addition, inert particles may be contained in another surface layer (base layer) or in an inner layer (core layer) in the case of three or more layers. In this case, it is preferable that the base layer or the inner layer (core layer) below the surface layer contains inert particles so that when the surface is formed with this layer, the surface roughness is lower than the surface roughness Ra of the surface layer. . Furthermore, the surface roughness R of the base layer and the inner layer
a is 2 nm or more, especially 4n, from the surface roughness Ra of the surface layer.
m or less is preferable.

Examples of such inert particles include (1) silicon dioxide (including hydrate, diatomaceous earth, silica sand, quartz and the like);
(2) alumina (crystal form: including α, β, γ, δ, θ, κ, etc.); (3) silicate containing at least 30% by weight of SiO ₂ (for example, amorphous or crystalline clay) Minerals, aluminosilicates (including calcined and hydrated), hot asbestos,
(Zircon, fly ash, etc.); (4) Mg, Zn, Z
(5) Ca and Ba sulfates; (6) Li, Ba, and Ca phosphates (including mono- and di-hydrogen salts); (7) Li, Na , And K
(8) terephthalates of Ca, Ba, Zn, and Mn; (9) Mg, Ca, Ba, Zn, C
(10) titanates of d, Pb, Sr, Mn, Fe, Co, and Ni; (10) chromates of Ba and Pb; (1
1) carbon (for example, carbon black, graphite, etc.); (12) glass (for example, glass powder, glass beads, etc.); (13) carbonate of Mg; (14) carbonate of Ca;
(15) fluorite; (16) ZnS; and (17) heat-resistant polymer particles (for example, silicone resin particles, crosslinked acrylic particles, crosslinked polystyrene particles, crosslinked polyester particles, Teflon particles, polyimide particles, melamine resin particles, etc.). Etc. are exemplified.

The average particle size of the inert particles is 0.05 to 3 μm.
m, more preferably 0.08 to 0.9 μm, especially 0.09 to 0.1 μm.
Preferably it is 49 μm. The content of the inert particles is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, particularly preferably 0.6% by weight or more, and 8% by weight or less, further 3% by weight or less, particularly preferably 0.9% by weight
The following is preferred.

In the biaxially oriented laminated polyester film of the present invention, the variation in the surface roughness Ra in the film width direction must be 5% / 500 mm or less.
When this variation is larger than 5% / 500 mm, when the slit product is wound under the winding condition suitable for the surface roughness Ra of the wide film, bumps are generated in the slit product having a small surface roughness Ra. When the slit product is wound under a winding condition suitable for the smaller surface roughness Ra of the wide film, wrinkles are easily formed in the slit product having a large surface roughness Ra, or the hardness of the winding is reduced. Because of the softness, the end face is likely to be misaligned, and in any case, the winding shape is unfavorably deteriorated. From these points, the variation in the surface roughness Ra in the film width direction is preferably 3% / 500 mm or less, more preferably 1% / 500 mm or less.

In the biaxially oriented laminated polyester film of the present invention, it is necessary that at least one surface layer has a thickness of 0.02 μm or more and 3 μm or less. When the thickness of the surface layer is less than 0.02 μm, the surface roughness Ra greatly changes with only a slight change in the thickness of the layer,
The dispersion of the surface roughness Ra increases, the number of protrusions due to the inactive particles decreases, and the slipperiness deteriorates, which is not preferable. If the surface roughness Ra is to be increased, the amount of the inert particles to be added becomes too large for the thickness of the layer, and the particles are easily shaved during traveling or the like. On the other hand, when the thickness is more than 3 μm, the change in the surface roughness Ra when the thickness of the surface layer is changed in the width direction becomes too small, and it becomes difficult to make the surface roughness Ra uniform in the width direction, which is not preferable. . From these points, the thickness of the surface layer is preferably 0.05 μm or more, more preferably 0.07 μm or more, and particularly preferably 0.2 μm or more, and less than 2.5 μm, further 2 μm or less, particularly 1 μm or less. It is preferably 0.45 μm or less.

The thickness of the surface layer varies in the film width direction and the refractive index in the longitudinal direction (n _MD ) and the refractive index in the width direction (n _MD ).
_TD ) (birefringence: Δn = n _MD −n _TD ), the thickness increases, especially the thickness t _{A of the} minimum birefringence part (A part) and the maximum birefringence part of the surface layer. (Part B) thickness t
It is preferable that _B satisfies the following expression 1.

[0029]

(Equation 4)

(Where t _A : thickness (μm) of the surface layer of part A) t _B : thickness (μm) of the surface layer of part B Δn _A : longitudinal refractive index n _MD and width direction refractive index n of part A Difference from _TD (birefringence: n _MD −n _TD ) Δn _B : Difference between longitudinal refractive index n _MD and width direction refractive index n _{TD of} part B (birefringence: n _MD −n _TD ) L: (Distance in the film width direction from part A to part B (m) D: Average particle size (μm) of lubricant contained in the surface layer.)

The birefringence index (Δn = n _MD −
n _TD ) takes a positive value when the longitudinal refractive index (n _MD ) is larger than the width direction refractive index (n _TD ), while it takes a negative value when it is smaller than the width direction refractive index (n _TD ). . The above equation 1 is also applied when the value takes a negative value.

(T_B-T_A) / T_AIs [(Δn_B−Δn
_A) / 2 × D] × √L, the film width
It is not possible to compensate for changes in physical properties in
It will be sufficient and not preferable. From this point, (t_B−
t_A) / T_AIs [(Δn_B−Δn _A) / D] × √L or more
Is more preferable, and [(Δn_B−Δn_A) /0.75×
D] × ΔL or more, and [(Δn_B−Δ
n_A) /0.5×D] × ΔL or more. other
One, (t_B-T_A) / T_AIs [20 (Δn_B−Δn_A)
/ D] × ΔL, the surface in the film width direction
The difference in layer thickness becomes too large, which causes
The uniformity of surface roughness deteriorates, which is not preferable.
The change in the thickness ratio with other layers is large, and the thickness unevenness is not bad
Is not preferred. From this point, (t_B-T_A) / T_AIs
[10 (Δn_B−Δn_A) / D] × √L or less is preferred
And [5 (Δn_B−Δn_A) / D] × ΔL or less
preferable.

In the above formula 1, the portion A and the portion B are usually the same film and are located at positions separated in the film width direction (direction perpendicular to the vertical direction), and at least 100 mm apart. From the viewpoint of easy measurement, a position separated by 300 mm or more is preferable, a position separated by 500 mm or more is more preferable, and a position separated by 900 mm or more is particularly preferable.

The thickness of the surface layer preferably satisfies a specific relationship with the inert particles contained in the surface layer. That is, the thickness t (μm) of the surface layer and the average particle diameter D (μm) of the inert particles contained in the surface layer
And the content W (wt%) preferably satisfies the following formulas (2) and (3).

[0035]

(Equation 5)

When (D × W) exceeds 2, the amount of particles in the surface layer increases, and the surface layer is liable to be shaved and the surface roughness is unfavorably increased. From this point, (D × W)
Is preferably 1.4 or less, more preferably 0.6 or less, and particularly preferably 0.2 or less. On the other hand, when (D × W) is less than 0.01, the amount of particles in the surface layer becomes small, and the slipperiness and blocking become poor, which is not preferable. From this point, (D × W) is equal to 0.
Preferably at least 02, more preferably at least 0.04,
0.08 or more is particularly preferable.

If (t / ΔD) is less than 0.1, the thickness of the surface layer is too small for the particle size, so that the particles are liable to fall off, or scraping occurs during the process. Not preferred. In this respect, (t / ΔD) is preferably equal to or greater than 0.2, more preferably equal to or greater than 0.25, and particularly preferably equal to or greater than 0.3. On the other hand, when (t / √D) exceeds 4, the thickness of the surface layer is too large for the particle size, and the surface roughness Ra is hardly changed even when the thickness of the surface layer is changed, and the effect of the present invention is not improved. It is not preferable because it is difficult to exhibit. From this point,
(T / ΔD) is preferably 2 or less, more preferably less than 1, and particularly preferably 0.5 or less.

In the present invention, when the width of the film is narrow (for example, 2000 mm or less), the surface thickness of the biaxially oriented polyester film changes in the film width direction and becomes larger as the orientation angle becomes larger. Preferably, the thickness satisfies a specific relationship with the orientation angle. That is, the minimum orientation angle (A 'part) of the surface layer
'And orientation angle up unit (B' thickness t _A and portion) of the thickness t _B 'preferably satisfies the following formula 4.

[0039]

(Equation 6)

(Where, t _A ': thickness of the surface layer in the A' part (μm) t _B ': thickness of the surface layer in the B' part (μm) θ _A ': orientation angle of the A' part (°) θ _B ′: Orientation angle of part B ′ (°) L ′: Distance (m) in the film width direction from part A ′ to part B ′)

Here, the orientation angle refers to the angle of inclination between the axis parallel to the longitudinal direction (longitudinal direction) of the film and the principal orientation axis.

In the present invention, the overall thickness of the biaxially oriented laminated polyester film has a certain thickness according to the purpose. Therefore, the thickness of the other layer (other surface layer, base layer, or inner layer) varies within a range where the entire thickness is maintained at a constant thickness in response to the thickness variation of the surface layer in the film width direction. May be.

The total thickness of the biaxially oriented laminated polyester film is usually from 1 to 300 μm, preferably from 2 to 8 μm.
0 μm, more preferably 2 to 25 μm, particularly preferably 4 to 17 μm. And base layer or inner layer (core layer)
Is preferably thicker than the surface layer.

If the overall film thickness becomes too thin,
The range in which the thickness of the surface layer can be changed becomes narrower, so that the roughness cannot be adjusted due to the change in the thickness of the surface layer, which is not preferable.
On the other hand, if the overall film thickness is too large, the ratio of the surface layer to the base layer becomes too small, making it difficult to produce a laminated film, and the thickness of the surface layer tends to vary, which is not preferable.

The biaxially oriented laminated polyester film of the present invention can be produced by a conventionally known method except that the properties of the surface layer in the film width direction are made uniform. For example, it can be manufactured by first producing a laminated non-oriented film and then biaxially orienting the film.

[0046] The laminated unoriented film is Ki de be produced by the production method of the accumulated laminated film conventionally, and the film layer forming the front <br/> surface layer, and the film layer forming a core layer and can be produced in the way <br/> method of the co-pressing and out you laminated in a molten state of the polyester. The co-extrusion method is not easy most express the effects of the present invention.

In the production of laminated non-oriented films having different layer thicknesses in the film width direction by co-extrusion, two or three or more manifolds are used in co-extrusion molding.
This can be achieved by changing the width of the die slit gap just before the outermost layer polymer merges with the other layer polymer in the width direction. Further, another method such as a feed block method may be adopted.

In the case of two layers, the surface layer opposite to the surface layer is formed of a base layer.

The film laminated by the above-mentioned method can be further made according to the conventional method of manufacturing a biaxially oriented film, and a biaxially oriented film can be obtained. For example, polyester is melted and co-extruded at a temperature of melting point (Tm: ° C.) to (Tm + 70) ° C. and has an intrinsic viscosity of 0.35 to 0.35.
A laminated unstretched film of 0.9 dl / g was obtained, and the laminated unstretched film was uniaxially (longitudinal or transverse) (Tg
-10) to (Tg + 70) ° C. (Tg: glass transition temperature of polyester) at a magnification of 2.5 to 5.0 times, and then in a direction perpendicular to the above-mentioned stretching direction (the first-stage stretching is a longitudinal direction). In the case of, the second-stage stretching is in the transverse direction).
It can be produced by stretching at a temperature of g (° C.) to (Tg + 70) ° C. at a magnification of 2.5 to 5.0 times. In this case, the area stretching ratio is preferably 9 to 22 times, more preferably 12 to 22 times. The stretching means may be either simultaneous biaxial stretching or sequential biaxial stretching. Of these, sequential biaxial stretching using a stenter for transverse stretching is preferred because the effect is most likely to be exhibited.

Further, the biaxially oriented film is (Tg + 7
0) It can be heat-set at a temperature of from 0 ° C. to Tm (° C.).
For example, a polyethylene terephthalate film is preferably heat-set at 190 to 240 ° C. The heat fixing time is, for example, 1 to 60 seconds.

The various physical properties and characteristics in the present invention are measured and defined as follows.

(1) Average Particle Diameter (Equivalent Area Circle Diameter) The following method is used to measure the equivalent area circle diameter of particles. 1) When the average particle diameter of the area circle equivalent diameter is determined from the powder. 2) When the average particle diameter of the area circle equivalent diameter of the particles in the film is determined.

1) In the case of powder The powder is scattered on an electron microscope sample stand so that individual particles do not overlap as much as possible, and a gold thin film deposition layer is formed on this surface with a thickness of 200 to 300 Å by a gold sputtering apparatus. Formed, and, for example, 100
Observation is performed at a magnification of 00 to 30,000, and the major axis, minor axis, and area circle equivalent diameter of at least 100 particles are determined using Luzex 500 manufactured by Nippon Regulator Co., Ltd. Then, the average particle size is calculated from these values.

2) From particles in the film: A small piece of the sample film was fixed on a sample table for a scanning electron microscope, and a sputtering device (JFC-
The film surface is subjected to ion etching under the following conditions using a 1100 type ion etching apparatus). The conditions are as follows: the sample is placed in a bell jar, the degree of vacuum is raised to a vacuum of about 10 ⁻³ Torr, the voltage is 0.25 kV, and the current is 1
Perform ion etching at 2.5 mA for about 10 minutes. Further, the film surface is subjected to gold sputtering with the same apparatus, observed at a magnification of 10,000 to 30,000 with a scanning electron microscope, and the average particle diameter is calculated in the same manner as in 1).

(2) Flatness of the film surface Ra (center line average roughness) is measured according to JIS B0601. Using a stylus type surface roughness meter (SURFCORDER SE-30C) manufactured by Kosaka Laboratory Co., Ltd., a chart (film surface roughness curve) is obtained under the condition of a needle radius of 2 μm and a load of 30 mg. A portion of the measured length L is extracted from the film surface roughness curve in the direction of the center line, and the center line of the extracted portion is set as the X axis, and the direction of the vertical magnification is set as the Y axis, and the roughness curve Y = f (x) In the expression, the value (Ra: nm) given by the following equation is defined as the roughness of the film surface.

[0056]

(Equation 7)

In the present invention, Ra is expressed as an average of five values excluding the largest value and the smallest value, with the measurement length being 1.0 mm and the cutoff value being 0.08 mm.

(3) Orientation Angle Using a polarizing microscope, the longitudinal direction (longitudinal direction) of the film
The angle of deviation of the main orientation axis from the axis parallel to is measured and defined as the orientation angle.

(4) Refractive Index and Birefringence Using sodium D line (589 nm) as a light source, methylene iodide was used as a mount liquid, and the Abbe refractometer was used to measure the refractive index in the longitudinal and width directions of the film. Measure. The difference (Δ) between the refractive index in the longitudinal direction (n _MD ) and the refractive index in the width direction (n _TD )
n = n _MD −n _TD ) is obtained and is defined as a birefringence.

(5) Layer Thickness Regarding the thickness of each layer of the laminated polyester film, attention was paid to the difference in the type and amount of the lubricant contained in each layer. Obtained by using a method of searching for a boundary surface by observation of a cross section with a transmission electron microscope.

(6) Winding properties (i) Roll winding form A When a film is wound into a wide and long roll shape having a width of 1000 mm and a length of 5000 m and a width of 500 mm and a length of 9000 m, it is easy to obtain a product having a good winding shape. To evaluate. ◎: When winding at a winding speed of 200 m / min into a wide and long roll, even if the winding conditions (tension, contact pressure, etc.) are changed,
Good rolls can be obtained over a fairly wide range. ：: When the winding conditions (tension, contact pressure, etc.) are changed at a winding speed of 200 m / min, wrinkles are easily formed, bumps (bump-shaped projections) are easily generated, and the condition range for good winding is narrow. Under certain conditions, an almost good roll is obtained. Δ: At a winding speed of 200 m / min, even if the winding conditions are variously changed, wrinkles and bumps appear, and an end face shift occurs, so that a good winding shape cannot be obtained. When the winding speed is set to 50 m / min, an almost good winding shape can be obtained by setting the winding conditions to specific conditions, but the speed is low, and it is somewhat insufficient industrially. ×: The winding speed (200 m / min, the winding speed 50 m / min, the winding conditions (tension, contact pressure, etc.) were variously changed,
Strong wrinkles, bumps (bumps),
A good rolled shape cannot be obtained due to displacement of the end face.

(Ii) Winding property B during magnetic tape production [Manufacture of magnetic tape] 100 parts by weight of γ-Fe ₂ O ₃ (hereinafter simply referred to as “parts”) and the following composition were ball milled for 12 hours. It was kneaded and dispersed.

Polyester polyurethane 12 parts Vinyl chloride-vinyl acetate-maleic anhydride copolymer 10 parts α-alumina 5 parts Carbon black 1 part Butyl acetate 70 parts Methyl ethyl ketone 35 parts Cyclohexane 100 parts After dispersion further fatty acid: oleic acid 1 part Fatty acid : 1 part of palmitic acid 1 part of fatty acid ester (amyl stearate) was added and kneaded for 10 to 30 minutes. Further, 7 parts of a 25% ethyl acetate solution of a triisocyanate compound was added,
The magnetic coating solution is prepared by high-speed shearing dispersion for one hour.

The obtained coating solution is applied onto a polyester film so that the dry film thickness becomes 2.5 μm (applied to the surface [rear surface or substrate layer surface] opposite to the surface layer characterized in the present invention). ).

Next, after performing orientation treatment in a DC magnetic field,
Dry at 00 ° C. After drying, a calendering treatment is performed, and a slit is formed to a width of 1/2 inch to obtain a magnetic tape.

[Evaluation of Winding Yield] Winding property is evaluated when slitting to a 1/2 inch width as described above. In the production of magnetic tapes, a large number of dozens of tapes each having a width of 1/2 inch are taken from a wide raw material of about 300 to 1500 mm, and the state of the winding shape at this time is determined based on the following. (Double-circle): At a winding speed of 300 m / min, the whole number can be wound neatly in a wide range of conditions such as the tension of the slitter. ：: When the conditions such as the tension of the slitter are changed at a winding speed of 300 m / min, there are conditions under which a good number of windings can be obtained, but the range is narrow. However, at a winding speed of 100 m / min, winding can be performed clearly over a wide range. Δ: When the conditions such as the tension of the slitter are changed at a winding speed of 300 m / min, there is no condition that the winding appearance of all the windings is good, but the end face deviation within 0.5 mm is partially observed, or Weak winding irregularities and deformation (bumps, etc.)
Is obtained (pancake) of a degree that can be seen, and is judged to be a usable level somehow. At 100 m / min, the conditions are narrow, but a beautiful winding can be obtained. ×: Even if the slitter conditions were changed at a winding speed of 300 m / min, a large end face deviation occurred, or unevenness and deformation (bumps, bumps, etc.) of the winding appeared strongly. , The whole is not a good roll,
Some unusable things (pancakes) come out. 1
Even at a winding speed of 00 m / min, even if the slitter conditions are changed, deviation of the end face (around 0.5 mm) is observed, and slight unevenness and deformation of the winding (such as bumps) are observed. XX: Even if the slitter conditions were changed at 300 m / min or 100 m / min, a large end face deviation occurred, and unevenness / deformation (bumps) of the winding appeared strongly, resulting in good winding. I can't get a figure.

[0067]

The present invention will be further described below with reference to examples.

Examples 1-3 and Comparative Example 1 Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer and Table 1 as a lubricant The polymer was polymerized in the usual manner by adding the additive particles shown in (1) and the intrinsic viscosity (orthochlorophenol, 35 ° C.) 0.62 dl /
g of polyethylene terephthalate for the surface layer and the core layer was obtained.

Next, the polyethylene terephthalate for the surface layer and the core layer was dried at 170 ° C. for 3 hours, supplied to separate extruders of a coextrusion film forming machine, and coextruded from a three-layer die to obtain a laminated unstretched film. Was. In order to make it possible to change the thickness ratio of each layer in the film width direction, the die spacing of each layer in the die portion of the manifold type three-layer die can be appropriately adjusted in the film width direction.

The unstretched film thus obtained was successively biaxially stretched at a longitudinal stretching ratio of 4.0 times and a transverse stretching ratio of 3.8 times. At this time, the temperature of the low-speed side stretching roll in longitudinal stretching is 66 ° C., and the IR heater is heated (surface temperature: 830 ° C.).
The transverse stretching was carried out at 97 ° C. using a stenter, and further heat-treated at 220 ° C.

The resulting biaxially oriented laminated film had a film width of 4.5 m at the point where it exited the stenter, and the width direction center of the film and 1000 m from the center.
A slit film having a width of 1000 mm was wound on a roll with a length of 5000 m under the same conditions to obtain four film rolls. All of Examples 1 to 3 had good winding and good winding appearance. On the other hand, in the case of Comparative Example 1, the one on the center side was wound up and the winding appearance was good, but the one on the side end side was insufficient in winding property and the winding appearance was also poor.

Of these film rolls, the center side (roll 1) and the side end side (roll 2) were coated with a magnetic layer by the above-described method, subjected to a calendering treatment, and then a 1/2 inch width. And rolled up into a pancake under the same conditions. Table 1 shows these characteristics.

Example 4 and Comparative Example 2 An ethylene glycol slurry containing crosslinked polystyrene particles was prepared, and this was subjected to a transesterification reaction with dimethyl terephthalate using manganese acetate as a transesterification catalyst. Was subjected to polycondensation using antimony trioxide as a polymerization catalyst and phosphorous acid as a stabilizer to obtain polyethylene terephthalate for a surface layer having an intrinsic viscosity of 0.70 dl / g.

The procedure was the same as described above except that the crosslinked polystyrene particles were not used, to produce polyethylene terephthalate having an intrinsic viscosity of 0.62 dl / g and containing substantially no inert particles, and used as a core layer.

Next, the polyethylene terephthalate for the surface layer and the core layer was dried under reduced pressure at 180 ° C. for 3 hours, respectively, and then supplied to separate extruders of a co-extrusion film forming machine. A stretched film was obtained. In order to make it possible to change the thickness ratio of each layer in the film width direction, the die spacing of each layer in the die part of the manifold type three-layer die can be appropriately adjusted in the film width direction.

The laminated unstretched film thus obtained was successively biaxially stretched at a longitudinal stretching ratio of 4.5 times and a transverse stretching ratio of 3.6 times. At this time, the temperature of the low-speed side stretching roll in longitudinal stretching is 66 ° C., and the IR heater is heated (surface temperature: 830 ° C.).
The transverse stretching was carried out at 100 ° C. using a stenter, and a heat treatment was further performed at 200 ° C. for 5 seconds.

The obtained biaxially oriented laminated film has a film width of 4.5 m at the position where the film exits the stenter. From this, four film rolls each having a width of 1000 mm are provided in the width direction of the stenter as in Example 1. Slit as
It was wound up to 000 mm width x 5000 m.

Further, the magnetic layer was applied by the above-mentioned method, subjected to a calendering treatment and the like, and then slit into a 1/2 inch width. The characteristics are shown in Table 2.

Example 5 Manganese acetate was used as a transesterification catalyst between dimethyl terephthalate and ethylene glycol, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer, and additive particles shown in Table 2 as a lubricant. And polymerized in a conventional manner, with an intrinsic viscosity of 0.67 dl / g
Of polyethylene terephthalate for the surface layer and for the core layer having an intrinsic viscosity of 0.60 dl / g.

Next, the polyethylene terephthalate for the surface layer and the core layer was dried at 170 ° C. for 3 hours, supplied to separate extruders of a co-extrusion film forming machine, and co-extruded from a three-layer die to obtain a laminated unstretched film. Was. In order to make it possible to change the thickness ratio of each layer in the film width direction, the die spacing of each layer in the die portion of the manifold type three-layer die can be appropriately adjusted in the film width direction.

The laminated unstretched film thus obtained was successively biaxially stretched at a longitudinal stretching ratio of 3.7 times and a transverse stretching ratio of 3.8 times. At this time, the temperature of the low-speed side stretching roll in the longitudinal stretching was 72 ° C., and the IR heater was heated (surface temperature: 830 ° C.).
The transverse stretching was carried out at 102 ° C. using a stenter, and further heat-treated at 220 ° C.

The resulting biaxially oriented laminated film had a film width of 4.5 m at the point where it exited the stenter. From this, four film rolls having a width of 1000 mm were taken in the width direction of the stenter as in Example 1. Slit as
It was wound up to 000 mm x 5000 m.

Further, the magnetic layer was applied by the above-mentioned method, subjected to calendering treatment and the like, slit into a 1/2 inch width, and wound up to 5000 m. The characteristics are shown in Table 2.

Example 6 In Example 5, biaxially stretching was carried out successively at a longitudinal stretching ratio of 3.4 times and a transverse stretching ratio of 4.3 times under the stretching conditions. The temperature was set to 76 ° C., the heating was performed in combination with the IR heater, the transverse stretching temperature was set to 107 ° C., and the thickness ratio of the surface layer was adjusted.
The characteristics are shown in Table 2.

[0085]

[Table 1]

[0086]

[Table 2]

Examples 7 to 11 Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst,
Phosphorous acid is added as a stabilizer, and the additive particles shown in Table 3 are further added as a lubricant, and polymerized by a conventional method, and polyethylene having an intrinsic viscosity (orthochlorophenol, 35 ° C.) of 0.62 dl / g for the surface layer and the core layer. Terephthalate was obtained.

Next, the polyethylene terephthalate for the surface layer and the core layer was dried at 170 ° C. for 3 hours, supplied to separate extruders of a co-extrusion film forming machine, and co-extruded from a three-layer die to obtain a laminated unstretched film. Was. In order to change the distribution of the thickness ratio of each layer in the film width direction,
In the die part of the three-layer die of the manifold type, the distance between the die of each layer can be appropriately adjusted in the film width direction.

The laminated unstretched film thus obtained was successively biaxially stretched at a longitudinal stretching ratio of 4.1 times and a transverse stretching ratio of 3.7 times. At this time, the temperature of the low-speed side stretching roll in longitudinal stretching is 66 ° C., and the IR heater is heated (surface temperature: 830 ° C.).
The transverse stretching was carried out at 97 ° C. using a stenter, and further heat-treated at 220 ° C.

The obtained biaxially oriented laminated film had a film width of 1.2 m after leaving the stenter, a center in the width direction of the film and 500 mm from the center.
The separated portions were slit, and a slit film having a width of 500 mm was wound around a roll with a length of 9000 m to obtain two film rolls.

One of these film rolls was coated with a magnetic layer by the method described above, subjected to a calendering treatment, slit into a 1/2 inch width, and wound up under the same conditions. Table 3 shows these characteristics.

[0092]

[Table 3]

[0093]

According to the present invention, it is possible to provide a biaxially oriented laminated polyester film in which variations in surface characteristics in the width direction are reduced.

────────────────────────────────────────────────── (5) References JP-A-5-309714 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B29C 47 / 00-47/96

Claims (5)

(57) [Claims] 1. A laminated polyester formed by co-extrusion.
A telfilm, wherein at least one surface layer has a thickness of 0.02 μm or more and 3 μm or less and varies in the film width direction.
Turned into and, and the surface roughness Ra of the surface layer 3 to 40
nm and the variation in the film width direction is 5% / 500 mm
A biaxially oriented laminated polyester film characterized by the following. 2. A method according to claim 1, wherein the thickness of the surface layer is a refractive index in the longitudinal direction (n _MD ).
2. The biaxially oriented laminated polyester film according to claim 1, wherein the larger the difference (birefringence: Δn) between the refractive index (n _TD ) and the width direction (birefringence: Δn), the greater the difference. 3. A birefringence smallest portion of the surface layer thickness of t _A and birefringence maximum of (A portion) (B portion) of the thickness t _B and is represented by the following formula 1
The biaxially oriented laminated polyester film according to claim 1 or 2, which satisfies the following. (Equation 1) (However, t _A : thickness of surface layer of part A (μm) t _B : thickness of surface layer of part B (μm) Δn _A : difference between longitudinal refractive index n _MD and width direction refractive index n _TD of part A Difference (birefringence: n _MD −n _TD ) Δn _B : Difference between longitudinal refractive index n _MD and width direction refractive index n _{TD of} part B (birefringence: n _MD −n _TD ) L: from part A (Distance in the film width direction to part B (m) D: Average particle size (μm) of lubricant contained in surface layer.) 4. The thickness t (μm) of the surface layer and the average particle diameter D (μm) and the content W (wt%) of the inert particles contained in the surface layer are expressed by the following formulas (2) and (3). Claim 1, which satisfies
4. The biaxially oriented laminated polyester film according to 2 or 3. (Equation 2) 5. The claims and the orientation angle up unit 'thickness t _A of (part orientation angle minimum portion of the surface layer A)' and (B 'part) of the thickness t _B' satisfy the following equation 4 1 Or the biaxially oriented laminated polyester film according to 2. (Equation 3) (However, t _A ': _A' portion of the surface layer having a thickness _{(μm) t B ': B} ' of the surface layer having a thickness (μm) θ _A: orientation angle 'A' section (°) θ _B ': (Orientation angle (°) of part B ′ L ′: distance (m) in the film width direction from part A ′ to part B ′.)