JPH05170943A - Polyester film - Google Patents

Abstract

PURPOSE:To provide the subject film containing specific fine particles and specific inert particles at a specific ratio, giving no damage on a plastic guide, having excellent abrasion resistance and scratch resistance and useful for magnetic recording medium, etc. CONSTITUTION:The objective film contains (A) 0.05-1wt.% of fine particles composed of multiple oxides of formula (x+y+z=1; y+z>=0.2; (x) is 0.2-0.8; (y) is 0-0.8; (z) is 0-0.8) and having a specific surface area of 40-100m<2>/g and an average secondary particle diameter of 0.05-0.30mum and (B) preferably 0.01-2wt.% of one or more kinds of inert particles such as calcium carbonate having an average particle diameter of 0.3-1.2mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film, and more particularly, it has excellent abrasion resistance and scratch resistance when used as a base film of a magnetic recording medium.
Further, it relates to a polyester film which does not damage the plastic guide.

[0002]

2. Description of the Related Art Biaxially oriented polyester films represented by polyethylene terephthalate films are widely used for magnetic recording media because of their excellent physical and chemical properties.

In a biaxially oriented polyester film, its slipperiness and abrasion resistance are major factors that affect the workability of the film manufacturing process and processing process, and the product quality. If these are insufficient, for example, when a magnetic layer is applied to the surface of a biaxially oriented polyester film and used as a magnetic tape, friction between the coating roll and the film surface is severe, and shavings are generated, or scratches are generated on the film surface. .. Also, VTR
Even when used for a data cartridge or the like, shavings or scratches are generated in the process of winding the cassette at a high speed, which causes dropout (D / O).

Particularly for VTR applications, metal guides or plastic guides whose surfaces are not sufficiently finished may be used for guide posts fixed in the cassette for the purpose of cost reduction recently. The surface of these guide posts is extremely rough. Therefore, for example, a method of adding inorganic particles such as silicon oxide, titanium dioxide, calcium carbonate, talc, clay and calcined kaolin (see, for example, JP-A-54-54).
57562) or a method of precipitating fine particles containing calcium, lithium or phosphorus in a polymerization system (see, for example, Japanese Patent Publication No. 52-32914), using a film having improved slipperiness and sharpness. Moreover, with a magnetic tape that does not have a back coat, shavings and scratches occur in the process of winding it in the cassette at high speed,
The frequency of D / O increases.

In order to solve such a problem, a method of reducing scratches on the post guide by adding particles of porous alumina, silica or titania having a high porosity (see, for example, JP-A-62-43450). Is proposed. However, even in this method, when the film is run at a higher speed, the effect is reduced in the case of silica particles, and the effect of scratch resistance is sufficient in the case of alumina particles, but the particle hardness is high, so the plastic guide is damaged. As a result, problems such as abrasion powder are generated.

[0006]

In view of the above situation, the present inventor has found that the polyester film for a magnetic recording medium has good abrasion resistance and scratch resistance even when a rough metal guide or a plastic guide is used. The present invention has been accomplished as a result of intensive research aimed at preventing the plastic guide from being damaged and exhibiting excellent properties.

[0007]

That is, the present invention comprises a complex oxide represented by the following formula and having a specific surface area of 40-
100 m ² / g, the average particle size of secondary particles is 0.05 to 0.
A polyester containing 0.05 to 1% by weight of fine particles (A) having a size of 30 μm, and further containing at least one kind of inert particles (B) having an average particle size of 0.3 to 1.2 μm. It is a film.

[0008]

Embedded image (Al ₂ O ₃ ) _x (TiO ₂ ) _y (SiO ₂ ) _z (where x, y, and z are molar ratios, and x + y + z =
1, y + z ≧ 0.2, x = 0.2 to 0.8, y = 0 to
0.8 and z = 0 to 0.8. )

The polyester in the present invention is a polyester having an aromatic dicarboxylic acid as a main acid component and an aromatic glycol as a main glycol component. Such polyesters are substantially linear and have film forming properties, especially film formation by melt molding. Examples of the aromatic dicarboxylic acid include terephthalic acid, naphthalenedicarboxylic acid, isophthalic acid, diphenoxyethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenylketonedicarboxylic acid and anthracenedicarboxylic acid. You can Examples of the aliphatic glycols include polymethylene glycol having 2 to 10 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, decamethylene glycol, and fats such as cyclohexanedimethanol. Examples thereof include cyclic diols.

In the present invention, polyesters containing alkylene terephthalate and / or alkylene naphthalate as a main constituent are preferably used as the polyester.

Among such polyesters, not only polyethylene terephthalate and polyethylene-2,6-naphthalate but also, for example, 80 mol% or more of the total dicarboxylic acid component is terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, A copolymer in which 80 mol% or more of all glycol components is ethylene glycol is preferable. 20 mol% or less of the total acid component can be the above aromatic dicarboxylic acids other than terephthalic acid and / or 2,6-naphthalenedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid and sebacic acid. A cycloaliphatic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid. Further, 20 mol% or less of the total glycol component may be the above-mentioned glycol other than ethylene glycol, or an aromatic diol such as hydroquinone, resorcin, 2,2-bis (4-hydroxyphenyl) propane, etc .; 1 An aliphatic diol having an aromatic ring such as 4-dihydroxydimethylbenzene; a polyalkylene glycol (polyoxyalkylene glycol) such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like can also be used.

In the polyester of the present invention, a component derived from an oxycarboxylic acid such as an aromatic oxyacid such as hydroxybenzoic acid or an aliphatic oxyacid such as ω-hydroxycaproic acid, a dicarboxylic acid component and an oxycarboxylic acid are used. Those which are copolymerized or bonded at 20 mol% or less based on the total amount of the acid component are also included.

Further, in the polyester of the present invention, a polycarboxylic acid or polyhydroxy compound having a functionality of 3 or more, such as trimellitate, can be used in an amount in a substantially linear range, for example, an amount of 2 mol% or less based on the total acid component. Also included are those obtained by copolymerizing acid, pentaerythritol and the like.

The above polyester is known per se and can be produced by a method known per se.

The polyester preferably has an intrinsic viscosity of about 0.4 to about 0.9, which is obtained by measuring at 35 ° C. as a solution in o-chlorophenol.

In the present invention, the fine particles (A) contained in the polyester film are composed of a complex oxide represented by the following formula.

[0017]

Embedded image (Al ₂ O ₃ ) _x (TiO ₂ ) _y (SiO ₂ ) _z (where x, y, and z are molar ratios, and x + y + z =
1, y + z ≧ 0.2, x = 0.2 to 0.8, y = 0 to
0.8 and z = 0 to 0.8. )

In the above, the molar ratio of Al ₂ O ₃ (x)
Is less than 0.2, the hardness of the particles is insufficient and the scratch resistance is poor. On the other hand, when it is more than 0.8, the hardness of the particles is too high and the plastic guide is damaged. Also, TiO
_When the molar ratio (y) of ₂ exceeds 0.8, shavings are often generated, while when the molar ratio (z) of SiO ₂ exceeds 0.8, the hardness of the particles is insufficient and the scratch resistance is inferior. become. Further, when the sum of the molar ratio (y) of TiO _{2 and} the molar ratio (z) of SiO ₂ is less than 0.2, the hardness of the particles is high and the plastic guide is damaged.

Fine particles (A) composed of the complex oxide
Can be synthesized, for example, by simultaneously supplying vapors of aluminum chloride, titanium tetrachloride and silicon tetrachloride into an oxyhydrogen flame and performing high temperature hydrolysis, but the production method is not particularly limited.

The fine particles made of the composite oxide (A) in the present invention has a specific surface area of 40 to 100 m ² / g, it is necessary and preferably 50~90m ² / g. When the specific surface area is less than 40 m ² / g, the primary particle diameter becomes too large and the scratch resistance is good, but shavings are likely to occur, and the plastic guide is frequently damaged. On the other hand, if it exceeds 100 m ² / g,
The primary particle diameter becomes too small, and the particles cannot form sufficient projections any more, and the effect of improving scratch resistance is lost.

Further, in the fine particles (A) made of the complex oxide, the average particle diameter of secondary particles is 0.05 to 0.3 μm.
Must be If the average particle size is less than 0.05 μm, the fine particles become too fine, and it becomes impossible to form fine protrusions necessary for scratch resistance and abrasion resistance.
On the other hand, when it is larger than 0.3 μm, the agglomeration of the particles is too large and shavings are likely to occur.

In the present invention, the content of the fine particles (A) is 0.05 to 1% by weight based on the polyester.
If this content is less than 0.05% by weight, the effect of adding fine particles becomes small, while if it exceeds 1% by weight, overlapping of the fine particles in the film is observed and shavings are likely to occur.

In the present invention, in addition to the fine particles (A) made of the above composite oxide, it is necessary to include inert particles (B) having an average particle size larger than this. The average particle size of the inert particles (B) is 0.3 to 1.2 μm. If the inert particles (B) are not present, the coefficient of friction with respect to various guides becomes high, which not only deteriorates scratch resistance and abrasion powder resistance, but also makes handling difficult in the manufacturing process of the biaxially oriented polyester film. In addition, the running property deteriorates when used as a base film for a magnetic recording medium. However, when particles larger than 1.2 μm are used, only a film having insufficient planar flatness can be obtained.

In the present invention, the content of the inert particles (B) is preferably 0.005 to 5% by weight, more preferably 0.01 to 2% by weight, based on the polyester. If this content is too small, the coefficient of friction will be high, and the action of the particles will not be sufficient. On the other hand, if it is too large, the dispersibility in the polymer will be insufficient and the abrasion resistance will deteriorate.

In the present invention, it is not necessary to specifically limit the type of the inert particles (B), and the particles (B) can be used.
As, for example, calcium carbonate, silicon dioxide, titanium oxide, aluminum oxide, inorganic inert particles such as kaolin,
Examples thereof include organic inert particles such as silicone and cross-linked polystyrene, and particles internally deposited by a polymerization catalyst.

The polyester of the present invention is melt-extruded at a temperature of, for example, a melting point (Tm: ° C.) to (Tm + 70) ° C. and an intrinsic viscosity of 0.35 to 0.9 dl / g.
Of unstretched film, and the unstretched film is uniaxially (longitudinal or lateral) (Tg-10) to (Tg + 7).
At a temperature of 0) ° C. (however, Tg: glass transition temperature of polyester), the film is stretched at a draw ratio of 2.5 to 5.0, and then in a direction perpendicular to the stretching direction (when the first stage stretching is the longitudinal direction,
The second stage drawing is in the transverse direction) and Tg (° C)-(Tg + 7
It can be produced by stretching at a temperature of 0) ° C. and a draw ratio of 2.5 to 5.0. In this case, the area stretch ratio is 9 to 22 times,
Further, it is preferably 12 to 22 times. The stretching means may be simultaneous biaxial stretching or sequential biaxial stretching.

Further, the polyester film has (Tg +
It can be heat-set at a temperature of 70) to Tm (° C). For example, polyethylene terephthalate film is preferably heat set at 190 to 230 ° C. The heat setting time is, for example, 1 to 60 seconds.

The reason why the polyester film of the present invention is excellent in abrasion resistance and scratch resistance is not clear, but the fine particles (A) are probably suitable for the particle shape, hardness and degree of aggregation. Seems to be the main reason. For example, the hardness of the particles is harder than silicon dioxide and more scratch resistant, and is softer than aluminum oxide and does not damage the plastic guide. Furthermore, it produces less shavings than titanium oxide.

[0029]

EXAMPLES The present invention will be described in more detail below with reference to examples. In addition, each characteristic value in an Example is based on the following method.

(1) Average particle size of particles 1) When determining the average particle size from a granular body Shimadzu CP-50 type Centrifugal particle size analyzer (Centrifugal Particle S
ize Analyser). The particle diameter corresponding to 50 mass% is read from the integrated curve of particles of each particle diameter calculated based on the obtained centrifugal sedimentation curve and the abundance thereof, and this value is taken as the above average particle diameter (Book Technology ", published by Nikkan Kogyo Shimbun, 1975, pp. 242-247).

2) Obtaining the average particle size from the particles in the film A small piece of the sample film is fixed on a sample stand for a scanning electron microscope, and a sputtering device (JFC-made by JEOL Ltd.) is used.
The film surface is subjected to ion etching treatment under the following conditions using a 1100 type ion etching apparatus). The condition is that the sample is placed in a bell jar and the degree of vacuum is raised to a vacuum state of about 10 ^-3 Torr. Voltage 0.25kV, current 1
Ion etching is performed at 2.5 mA for about 10 minutes. Further, gold sputtering is applied to the film surface with the same apparatus, and it is observed with a scanning electron microscope to 50,000 to 10,000.
Observed at double magnification, the equivalent spherical diameter distribution of at least 100 particles is determined by Luzex 500 manufactured by Nippon Regulator Co., Ltd., and calculated from the weight cumulative 50%.

(2) Specific surface area of powder, total pore volume BET was measured by using Autosorb-1 manufactured by Kantachrome Co., Ltd.
The specific surface area and total pore volume are measured by the method.

(3) Coefficient of running friction of film (μk) It is measured as follows using the apparatus shown in FIG.
In FIG. 1, 1 is an unwind reel, 2 is a tension controller, 3, 5, 6, 8, 9 and 11 are free rollers, 4 is a tension detector (inlet), and 7 is a fixing rod made of stainless steel SUS304 (outside). Diameter 5mmφ, surface roughness Ra =
0.02 μm), 10 is a tension detector (exit), 1
Reference numeral 2 is a guide roller, and 13 is a take-up reel.

At a temperature of 20 ° C. and a humidity of 60%, the width is 1 /
The film cut into 2 inches is attached to a fixed rod of 7 at an angle θ =
(152/180) π radians (152 °) are brought into contact and moved (rubbed) at a speed of 200 cm per minute. When the tension controller 2 is adjusted so that the inlet tension T ₁ becomes 35 g, the outlet tension (T ₂ : g) is detected by the outlet tension detector after the film has run 90 m, and the running friction coefficient μk is calculated by the following formula. calculate.

[0035] μk = (2.303 / θ) log (T 2 / T 1) = 0.868log (T 2/35)

(4) Flatness of the film surface Ra (center line average roughness) is measured according to JIS B 0601 by a Tokyo Seimitsu Co., Ltd. stylus surface roughness meter (SU).
Using RFCOM3B), lay a chart (film surface roughness curve) under the conditions of a needle radius of 2μ and a load of 0.07g,
From the obtained film surface roughness curve, a portion of the measurement length L is extracted in the direction of its center line, the center line of this extracted portion is taken as the X axis, and the direction of longitudinal magnification is taken as the Y axis.
= F (x), the value (R
a: μm) is defined as the flatness of the film surface.

[0037]

[Equation 1]

In the present invention, 8 pieces are measured with a reference length of 0.25 mm, and Ra is expressed as an average value of 5 pieces obtained by removing 3 pieces from the larger value.

(5) Scratch resistance and abrasion resistance In a device similar to that used in FIG. 1 used for measuring the running friction coefficient μk, the winding angle was set to 30 ° and the inlet tension was set to 50 g at a speed of 300 m / min. Drive for 300m. The shavings adhering to the fixed rod 7 after running and the scratches of the tape after running are evaluated. At this time, as a fixing rod, a 6φ tape guide (surface roughness Ra = 0.15 μm) obtained by bending a SUS sintered plate into a cylindrical shape and having an insufficient surface finish
A is used as the method A, and a 6φ tape guide made of carbon black-containing polyacetal is used as the method B.

<Judgment of shavings> ◎: No shavings are observed ○: Slightly shavings are seen △: Presence of shavings is visible at a glance ×: Shavings are severely adhered

<Scratch Judgment> ⊚: No scratches were found ◯: 1 to 5 scratches were found Δ: 6 to 15 scratches were found ×: 16 or more scratches were found

(6) Scratch resistance of plastic guide Scratch resistance and abrasion resistance measurement The film was run for 1000 m under the same conditions as in Method B, and then the tape guide made of polyacetal was taken out and the scratched state was visually evaluated.

⊚: No scratches were observed ○: Slight scratches were observed Δ: Scratches were visible at a glance ×: Scratches were remarkable

[0044]

Examples 1 to 5 and Comparative Examples 1 to 9 Dimethyl terephthalate and ethylene glycol, manganese acetate as a transesterification catalyst, antimony trioxide as a polymerization catalyst, phosphorous acid as a stabilizer, and a lubricant as shown in Table 1. The particles shown were added and polymerized by a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity of 0.62 (orthochlorophenol, 35 ° C.).

The polyethylene terephthalate pellets were dried at 170 ° C. for 3 hours and then fed to an extruder hopper,
Melt at a melting temperature of 280 to 300 ° C., and surface finish this molten polymer through a 1 mm slit die for 0.3 s.
Extruded on a rotating cooling drum with a surface temperature of 20 ° C.
An unstretched film of 00 μm was obtained.

The unstretched film thus obtained is preheated at 75 ° C., and further 15 m between low speed and high speed rolls.
From above, it was heated with one IR heater having a surface temperature of 900 ° C., stretched to 3.6 times, rapidly cooled, then supplied to a stenter, and stretched laterally to 3.9 times at 105 ° C. ..
The obtained biaxially oriented film was heat set at a temperature of 205 ° C. for 5 seconds to obtain a heat set biaxially oriented film having a thickness of 14 μm.

On the other hand, 100 parts by weight of γ-Fe ₂ O ₃ (hereinafter simply referred to as “part”) and the following composition were mixed with a ball mill to obtain 12 parts.
Kneading and dispersion were performed for an hour.

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 Cyclohexanone 100 parts Further dispersed fatty acid oleic acid 1 part Palmitic acid 1 part Fatty acid ester (amyl stearate) 1 part

Add and knead for 15 to 30 minutes. Further, 7 parts of a 25% ethyl acetate solution of a triisocyanate compound was added, and the mixture was subjected to high speed shear dispersion for 1 hour to prepare a magnetic coating solution.

The obtained coating solution was applied onto the above-mentioned biaxially oriented polyester film having a thickness of 14 μm to give a dry film thickness of 3.5 μm.
Was applied so that

Then, after orientation treatment in a DC magnetic field, 10
It was dried at 0 ° C. After drying, calendering treatment was performed and slit to a width of 1/2 inch to obtain a magnetic tape having a thickness of 17.5 μm. The characteristics of this tape are shown in Table 1.

[0052]

[Table 1]

[0053]

According to the present invention, it is possible to provide a polyester film which is excellent in abrasion resistance and scratch resistance and which does not damage the plastic guide. The polyester film is particularly useful as a base film for magnetic recording media. Is.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus for measuring a running friction coefficient of a film.

[Explanation of symbols] 1 unwind reel 2 tension controller 4 tension detector (entrance) 7 fixed rod 10 tension detector (exit) 12 guide roller 13 take-up reel

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B29L 7:00 4F C08L 67:00

Claims (2)

[Claims] 1. Fine particles of a complex oxide represented by the following formula having a specific surface area of 40 to 100 m ² / g and an average secondary particle diameter of 0.05 to 0.30 μm
5 to 1% by weight, further having an average particle size of 0.3 to 1.2μ
A polyester film containing at least one of m inactive particles. Embedded image (Al ₂ O ₃ ) _x (TiO ₂ ) _y (SiO ₂ ) _z (where x, y, and z are molar ratios, and x + y + z =
1, y + z ≧ 0.2, x = 0.2 to 0.8, y = 0 to
0.8 and z = 0 to 0.8. ) 2. The polyester film according to claim 1, wherein the content of the inert particles is 0.005 to 5% by weight.