JP3172026B2 - Easy adhesion 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 an easily-adhesive polyester film, and more particularly to an easily-adhesive polyester film having excellent adhesion, blocking resistance, abrasion resistance and the like, and having a low chargeability.

[0002]

2. Description of the Related Art Biaxially oriented polyester films represented by biaxially oriented polyethylene terephthalate films are:
Due to its excellent physical and chemical properties, it is widely used especially as a base film for magnetic recording media. And
Recently, for the purpose of improving the adhesiveness with the magnetic layer and simplifying the process of producing the magnetic tape (improving the production efficiency), the easily-adhesive polyester film obtained by applying the easily-adhesive layer to the biaxially oriented polyester film is becoming mainstream. is there.

In the production of magnetic tapes, the speed of the process has been increased and the coating method has been shifted to use a die coater in order to improve productivity. This shift is a more severe (easy to cut) condition for the base film and the coated magnetic layer from the viewpoint of the cutability. Also, from the viewpoint of charging, the speeding up of the process is in the direction of easier charging.

[0004] The shavings of the base film in this step are:
The cause of dropout (D / O) and the cause of coating streaks at the time of coating the magnetic layer, while the shaving of the magnetic layer directly or quadratically causes the D / O. Further, the deterioration of the charging property makes it easy for the shaving powder or external foreign matter to adhere to the base film, and causes D / O due to the foreign matter. In particular, high-density recording has been performed on magnetic recording media, and even smaller adhered foreign substances and coating defects have caused D / O.

[0005] From these viewpoints, as an easily adhesive polyester film, excellent adhesion, blocking resistance,
There has been a demand for an easily-adhesive polyester film having abrasion resistance and having a property of low chargeability.

Various easy adhesives have been studied and proposed for imparting adhesiveness, but the purpose is to balance adhesiveness, blocking properties, coating properties and the like. From the viewpoint of abrasion resistance,
No measures have been taken.

On the other hand, various types of lubricants and surface properties have been studied and proposed for plain base films (films to which no easy-adhesive is applied) from the viewpoint of abrasion resistance. However, regarding the abrasion resistance when an easy-adhesive layer is applied thereon, since the easy-adhesive directly contacts the metal roll or the die coater, the behavior is considerably different from the sharpness of the plain product, Further, it was difficult to improve the abrasion resistance of the magnetic layer only from the viewpoint of the lubricant in the base film or the surface properties.

In order to improve the chargeability, a conductive film in which a conductive material is kneaded into a base film or an antistatic agent is added to an easily adhesive layer has been proposed, but from the viewpoint of abrasion resistance. Sufficient characteristics have not been obtained.

[0009]

The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the base polyester film and the easy-adhesive layer have a specific composition, and by combining them, the excellent properties can be obtained. The present inventors have found that it is possible to obtain an easily-adhesive polyester film having improved adhesiveness, blocking resistance, and abrasion resistance, and having a property of low chargeability.

[0010]

That is, the present invention provides (A) heat-resistant polymer particles and (B) alumina particles and / or
Alternatively, on at least one surface of the biaxially oriented polyester film containing colloidal silica particles, (C) 5 to 18 mol% of sulfonic acid groups in the molecule (per total dicarboxylic acid components), and a secondary transition point of 50 to 85 ° C. aqueous polyester resin and (D) an average particle size of 10 to 200 parts by weight based on 100 parts by weight of the aqueous polyester resin.
The thickness of the layer (nm) and the average particle size (n) of the colloid particles (D) are provided.
m) satisfies the following formula (1), and the surface roughness SRz of the film is 50 to 500 nm.

[0011]

0.3 ≦ (thickness of coating layer / average particle size of colloidal particles) ≦ 3.0─── (1) The polyester in the present invention is composed of an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol. Is a polyester having a main glycol component. Such polyesters are substantially linear and have film-forming properties, especially by melt-forming.

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, anthracene dicarboxylic acid and the like. Can be mentioned.

Examples of the aliphatic glycol include those having 2 carbon atoms such as ethylene glycol, trimethylene glycol, tetramethylene glycol, pentamethyl glycol, hexamethyl glycol, decamethylene glycol and the like.
And alicyclic diols such as polymethylene glycol or cyclohexane dimethanol.

As the polyester in the present invention, those containing alkylene terephthalate and / or alkylene naphthalate as a main component are preferably used.

Among these polyesters, in particular, polyethylene terephthalate, polyethylene {2,6} naphthalate, terephthalic acid and / or 2,6-naphthalenedicarboxylic acid account for at least 80 mol% of all dicarboxylic acid components, and 80% of total glycol components. A copolymer in which at least mol% is ethylene glycol is preferred. At that time, 2 of all acid components
0 mol% or less 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, sebacic acid, etc .; It can be an alicyclic dicarboxylic acid such as 4-dicarboxylic acid. Further, 20 mol% or less of the total glycol component can be the above-mentioned glycol other than ethylene glycol. For example, hydroquinone, resorcinol, 2,2─
Aromatic diols such as bis (4-hydroxyphenyl) propane; aliphatic diols having an aromatic ring such as 1,4-dihydroxydimethylbenzene; polyalkylene glycols (polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.) Oxyalkylene glycol) and the like.

The polyester in the present invention includes:
For example, aromatic oxyacids such as hydroxybenzoic acid, ω─
Also included are those obtained by copolymerizing an oxycarboxylic acid component such as an aliphatic oxyacid such as hydroxycaproic acid in an amount of 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:
A tri- or higher functional polycarboxylic acid component or a polyhydroxy compound component such as trimellitic acid or pentaerythritol may be used in a substantially linear range, for example, an amount of 2 mol% or less based on the total acid component. Polymerized ones are also included.

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

As the above-mentioned polyester, those having an intrinsic viscosity of 0.4 to about 0.9 measured at 35 ° C. as a solution in o-chlorophenol are preferred.

In the present invention, the particles contained in the biaxially oriented polyester film include (A) heat-resistant polymer particles and (B) alumina particles and / or colloidal silica particles. By combining these particles, a film having excellent abrasion resistance can be obtained. Other particles may be added to these particles, but combinations of other particles,
The combination of the particles (A) or the particles (B) and other particles does not provide sufficient abrasion resistance.

The heat-resistant polymer particles (A) have a 5% heat reduction temperature of 310 ° C. or more in a nitrogen gas atmosphere,
Particles composed of a polymer having a temperature of 30 ° C. or higher, particularly 350 ° C. or higher are preferred. Examples of such particles include silicone resin particles, crosslinked acrylic resin particles, crosslinked polystyrene particles, Teflon particles, polyimide particles and the like.
Among them, silicone resin particles are preferred.

The average particle size of the heat-resistant polymer particles (A) is preferably from 0.3 to 1.2 μm, more preferably from 0.4 to 0.8 μm. 0.005 to 0.3% by weight, more preferably 0.01 to
It is preferably 0.15% by weight, particularly preferably 0.02 to 0.05% by weight.

The heat-resistant polymer particles (A) further include
The volume shape factor (f) represented by the following equation (2) is 0.4 to
It is preferably in the range of π / 6.

[0024]

F = V / D ³ ───── (2) where f = volume shape factor V = average particle volume (μm ³ ) D = average maximum particle size (μm)

The alumina particles (B) can have various crystal forms, but preferably have at least one crystal form selected from the α, θ, and γ types, and particularly the θ type crystal form. Or a crystal form in which a small proportion of the α-form crystal form is contained in the γ-form crystal form is preferable. Such alumina particles are not particularly limited by the manufacturing method, and can be manufactured by a conventionally known method.

The colloidal silica particles (B) preferably contain 100 to 3000 ppm of Na by weight. When the content of Na is out of the above range, the effect of improving scratch resistance is poor, the independent existence ratio of particles in the film is reduced, and the abrasion resistance is likely to be deteriorated. For the production of the colloidal silica particles, there are methods such as a dialysis method, an electrolysis method, a salt precipitation method, and a method of producing an active silica sol by using an ion exchange resin using sodium silicate as a starting material, followed by polymerization, and the like. The most preferred is an ion exchange resin polymerization method.

The average particle size of the alumina particles and / or colloidal silica particles (B) is preferably from 0.02 to 0.3 μm, more preferably from 0.05 to 0.25 μm. 0.05 to 1.0% by weight, more preferably 0.1 to 0.5% by weight, especially 0.15 to 0.5% by weight.
Preferably, it is 4% by weight.

In the present invention, in order to mix the heat-resistant polymer particles and the alumina particles and / or the colloidal silica particles with the polyester intimately, these particles are added before or during the polymerization of the polyester, and the mixture is added to the reaction vessel. The polyester may be kneaded, or may be sufficiently kneaded with the polyester in an extruder when pelletizing after completion of polymerization or when melt extruding into a sheet.

The biaxially oriented polyester film of the present invention can be basically produced from the above polyester by a known method. That is, the melted polyester is extruded into a sheet by an extruder, solidified by cooling, then sequentially or simultaneously biaxially stretched, and further heat-treated under tension or limited shrinkage. If necessary, the heat-treated film can be produced by a method of re-heating.

For example, the melting point (Tm: ° C.) to (Tm + 7)
0) The polyester is melted at a temperature of ° C. to have an intrinsic viscosity of 0.3.
An unstretched film of 5 to 0.9 dl / g is obtained, and the unstretched film is uniaxially (longitudinal or transverse) (Tg─1
0) to (Tg + 70) ° C. (however, 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 the longitudinal direction). In the case, the second stretching is in the transverse direction).
It can be produced by stretching at a temperature of (° 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.

Further, the biaxially oriented film has (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 230 ° C. The heat fixing time is, for example, 1 to 60 seconds.

In the present invention, the poultice layer (adhesive layer) provided on at least one side of the biaxially oriented polyester film
Is (C) 5-18 mol% of sulfonic acid groups in the molecule
A layer mainly composed of an aqueous polyester resin (water-soluble or water-dispersible polyester resin) having a second transition point of 50 to 85 ° C. (per total didicarboxylic acid component) and (D) colloid particles.

The sulfonate group in the aqueous polyester resin (C) is a group represented by ─SO ₃ M (where M is a metal atom, an ammonium group or a quaternary amine in an equivalent amount to ─SO ₃ ) The ratio is preferably 5 to 18 mol%, preferably 8 to 8 mol%, based on all dicarboxylic acid components.
It is 15 mol%, particularly preferably 9 to 12 mol%. If this proportion is less than 5 mol%, the water dispersibility and coatability of the polyester resin will be poor, while if it exceeds 18 mol%, the adhesion and blocking resistance will be reduced.

To introduce a sulfonate group into the polymer molecule, a functional compound having a sulfonate group, for example, 5-Na sulfoisophthalic acid, 5-ammonium sulfoisophthalic acid, 4-Na sulfoisoisophthalic acid,
A dicarboxylic acid component having a sulfonic acid group such as methylammonium sulfoisophthalic acid, 2-Na sulfoisophthalic acid, 5-K sulfoisophthalic acid, 4-K sulfoisophthalic acid, and 2-K sulfoterephthalic acid;

[0035]

Embedded image

It is preferable to use a dihydroxy compound component having a sulfonic acid group. Among these, a dicarboxylic acid component having a sulfonate group is preferable, and two or more of these can be used.

As the acid component constituting the aqueous polyester resin, terephthalic acid, isophthalic acid, phthalic acid,
Examples thereof include 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid, and dimer acid. Two or more of these components can be used. Further, together with these components, unsaturated polybasic acids such as maleic acid, fumaric acid, itaconic acid and the like, p-hydroxybenzoic acid, p─ (β
Hydroxycarboxylic acids such as (hydroxyethoxy) benzoic acid can be used in small proportions. The proportion of unsaturated polybasic acid component or hydroxycarboxylic acid component is at most 10 mo
1%, preferably 5 mol% or less. As the dihydroxy compound component, ethylene glycol, 1,4
─butanediol, neopentyl glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, xylylene glycol, dimethylolpropionic acid, glycerin, trimethylolpropane, poly (ethylene oxide) Examples thereof include glycol, poly (tetramethylene oxide) glycol, and an alkylene oxide adduct of bisphenol A.
Two or more of these components can be used.

The aqueous polyester resin has a secondary transition point (DSC method) of 50 to 85 ° C., preferably 60 to 80 ° C.
° C, more preferably 65-75 ° C. If the secondary transition point is less than 50 ° C., the abrasion resistance and blocking resistance decrease, while if it exceeds 85 ° C., the adhesiveness and coatability decrease.

The aqueous polyester resin can be produced by a method known as a method for producing polyester. At this time, the types and proportions of the dicarboxylic acid component and the dihydroxy compound component may be appropriately selected from the above-mentioned polymer characteristics. The number average molecular weight of the aqueous polyester resin can be freely selected, but is preferably from 5,000 to 28,000.

The colloid particles (D) include:
Examples include inorganic inert particles such as silicon oxide (including colloidal silica), tin oxide, zirconium oxide, titanium oxide, aluminum oxide, kaolin, talc, carbon, silicon carbide, calcium carbonate, barium sulfate, and metal colloid. Among them, colloidal silica is preferred. In addition, silicone resin particles, cross-linked acrylic resin particles,
Organic inert particles such as cross-linked polystyrene particles, cross-linked polyester particles, Teflon particles, and polyimide particles are exemplified.

The average particle size of the colloid particles (D) is 10
２００200 nm, preferably 30-150 nm, more preferably 50-120 nm. This average particle size is 10n
If it is less than m, the particles are too small to exert sufficient effects on blocking resistance and abrasion resistance of the magnetic layer.
If it exceeds 0 nm, the particles are easily chipped off, and the chipping resistance of the base deteriorates. The colloid particles (D)
It is preferable that the volume shape factor (f) represented by the formula (2) is in the range of 0.4 to π / 6.

The amount of the colloidal particles (D) is 5 to 20 parts by weight based on 100 parts by weight of the aqueous polyester resin.
0 parts by weight, preferably 10 to 100 parts by weight, more preferably 20 to 70 parts by weight. If the amount is less than 5 parts by weight, the effect on the blocking resistance and the abrasion resistance of the magnetic layer will not be sufficiently exhibited, while if it exceeds 200 parts by weight, the particles will easily aggregate and the abrasion resistance of the base will be poor.

If necessary, other resins, antistatic agents, lubricants, fillers, coloring agents, ultraviolet absorbers, antioxidants, surfactants may be added to the coating liquid for forming the easily adhesive layer, preferably the aqueous coating liquid. ,
In order to improve the heat resistance and blocking resistance of the easy contacting agent, a crosslinking agent such as melamine, epoxy, and aziridine compound may be added. The aqueous coating liquid may contain a small amount of an organic solvent.

The solid content concentration of the coating solution can be arbitrarily determined.
It is 1 to 15 wt%, preferably 2 to 12 wt%, and more preferably 4 to 10 wt%.

The amount of Wet applied is not particularly limited.
Traveling film (single film) 1m ² per 0.5
The thickness is preferably 30 g, more preferably 1 to 20 g, and the coating thickness after Dry is 20 to 200 nm, and more preferably 30 to 200 g.
150 nm, especially 40 to 120 nm, is preferred.

Further, the coating thickness (n
m) represents the relationship between the average particle size (nm) of the colloid particles and the following equation (1).

[0047]

0.3 ≦ (thickness of coating layer / average particle size of colloid particles) ≦ 3.0３ (1) Preferably, the relationship of the following formula (3) is satisfied.

[0048]

0.4 ≦ (thickness of coating layer / average particle size of colloid particles) ≦ 2.0─── (3) More preferably, the relationship of the following formula (4) is satisfied.

[0049]

0.5 ≦ (thickness of coating layer / average particle size of colloid particles) ≦ 1.5─── (4) (Thickness of coating layer / Average particle size of colloid particles)
Is less than 0.3, the particles are liable to be scraped off and the abrasion resistance of the base is deteriorated. On the other hand, when it is more than 3.0, the effects on the blocking resistance and the abrasion resistance of the magnetic layer cannot be sufficiently exhibited.

As a coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a reverse coating method, a roll brushing method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method, or the like may be used alone or in combination.

The coating solution may be applied to a biaxially oriented polyester film, but is preferably applied to a vertically uniaxially stretched polyester film.

The uniaxially stretched polyester film coated with the aqueous coating solution is dried, stretched in the horizontal direction, and optionally stretched again in the longitudinal direction.
Next, it is led to a step such as a heat setting treatment. For example, a longitudinally uniaxially stretched polyester film coated with an aqueous coating solution is guided to a stenter and is horizontally stretched, if desired, re-longitudinal stretched, and thermally fixed. During this time, the coating solution dries and forms a continuous film on the film. Drying may be performed before or during the transverse stretching.

The easily adhesive polyester film of the present invention has a surface roughness SRz of 50 to 500 nm, preferably 100 to 400 nm, and more preferably 150 to 300 nm.
nm. If the surface roughness SR _Z is less than 50 nm, the abrasion resistance of the base against the metal roll is deteriorated.
If it exceeds 00 nm, the base will have poor abrasion resistance to the die coater.

The surface roughness Ra of the easily adhesive polyester film in the present invention is not particularly limited. However, when used as a base film of a magnetic recording medium, from the viewpoint of electromagnetic conversion characteristics, it is preferably 40 nm or less, more preferably 20 nm.
The thickness is particularly preferably 15 nm or less.

The thickness of the easily adhesive polyester film in the present invention is preferably in the range of 4 to 100 μm for magnetic tapes, and 25 to 100 μm for floppy disks.
１００100 μm is preferred.

The easily adhesive polyester film of the present invention can be used for various coatings such as UV ink, offset ink,
High adhesion to chemical matte paint, diazo paint, magnetic paint, etc., especially strong adhesion to magnetic paint,
And it shows good blocking resistance without tackiness. In addition, the easy-to-contact layer has excellent abrasion resistance. For example, since there is almost no shavings generated during the coating process of magnetic paint, and the chargeability is low, little shavings and extraneous foreign substances are almost absorbed by the film. Without dropout (D
/ O) is obtained. This low charging property is particularly exhibited when an easy-adhesion layer is provided on both surfaces of the film, such as a floppy disk.

The physical property values and characteristics in the present invention are measured as follows. (1) Secondary transition point The secondary transition point of the polyester resin is determined by using a DSC at a heating rate of 20 ° C./min. (2) Average particle size of particles CP # 50 Centrifugal Particle Size Analyzer manufactured by Shimadzu Corporation (Centrifugal)
The measurement is performed using a Particle Size Analyzer. The particle size corresponding to 50% by mass is read from the integrated curve of the particles of each particle size and its abundance calculated on the basis of the obtained centrifugal sedimentation curve, and this value is defined as the above average particle size (Book "particle size measurement Technology, published by The Nikkan Kogyo Shimbun, 1975, pp. 242 to 247).

(3) Surface roughness SRz Needle diameter 2 μm using a three-dimensional roughness meter (manufactured by Kosaka Laboratories)
R, stylus pressure 30 mg, measurement length 1 mm, sampling pitch 2 μm, cutoff 0.25 mm, vertical magnification 20,000 times, horizontal magnification 200 times, biaxially oriented polyester film under the conditions of 100 scanning lines A three-dimensional image of the profile of the protrusions on the surface of. 5 points for the thus obtained profile from high protrusions order and 5 keeping score from a low order of valleys, determined both (projections and valleys) respective heights average value, defines the difference between SR _Z.

(4) Blade Sharpening Using the apparatus shown in FIG. 1, a sample film slit to a half inch width is directed at a 6 ° angle to a blade (a blade for an industrial razor testing machine manufactured by GKI, USA). The blade is run for 40 m at a tension of 300 g and a running speed of 100 m / min, and the abrasion resistance is evaluated based on the amount of shaving powder adhering to the blade edge.

This evaluation method corresponds well to the generation of shaving powder of a die coater in a coating step in the production of a magnetic tape.

<Judgment> ：: The shaving powder is slightly adhered. ○: The shaving powder is slightly adhered. △: The shaving powder is slightly adhered. ×: The shaved powder is considerably adhered.

(5) Sharpening of Metal Pin Using the apparatus shown in FIG. 2, a sample film slit to a 1/2 inch width was wound around a 6φ SUS fixing pin (surface roughness Ra = 15 nm) at a winding angle of 30 °. Run for 40m at a tension of 300g and running speed of 100m / min.
The abrasion resistance is evaluated based on the amount of shaving powder adhering to the SUS fixing pin.

This evaluation method corresponds well to the generation of metal roll (pass roll) shavings in the film and magnetic tape manufacturing processes.

<Judgment> ：: Little shavings adhered. ○: A little shavings adhered. △: A little shavings adhered. ×: Shaved powder considerably adhered.

(6) Running Friction Charging Using the apparatus shown in FIG. 3, a sample film slit to a 1/2 inch width was wound around a 6φ SUS fixing pin (surface roughness Ra = 15 nm) at a winding angle of 105 °. The film is run for 20 m at a tension of 100 g and a running speed of 2 m / min, and the surface potential of the film after pin friction is measured with a surface electrometer (Model 341-JX manufactured by TREK).

This evaluation method corresponds well to film charging with a metal roll (pass roll) in the film and magnetic tape manufacturing processes.

<Judgment> ：: Film surface potential (absolute value) is less than 1 kv ：: Film surface potential (absolute value) is 1 kv or more to 2 kv
Less than Δ: Film surface potential (absolute value) is 2 kv or more to 3 kv
Less than ×: Film surface potential (absolute value) is 3 kv or more

(7) Adhesion (Evaluation of MAG scratches) The following magnetic coating was applied to the coated surface of the sample film using a Meyer bar so that the thickness after drying was about 4 μm, and dried at 100 ° C. for 3 minutes. . Thereafter, aging is performed at 60 ° C. for 24 hours.

[Evaluation magnetic coating material] Polyester resin Byron 20SS 30 parts by weight (manufactured by Toyobo) PVC / vinyl acetate resin Esrec A 10 parts by weight (manufactured by Sekisui Chemical) Dispersant Ratio P 3 parts by weight (manufactured by Riken Vitamin) ) 260 parts by weight of a magnetic agent CTX-970 (manufactured by Toda Kogyo Co., Ltd.) is dissolved in a mixed solvent of methyl ethyl ketone / toluene / methyl isobutyl ketone to make a 30% liquid, and dispersed by a sand grinder for 2 hours. Then the crosslinking agent Coronate L
12 parts by weight (in terms of solid content) are added, and the mixture is stirred well to obtain a magnetic paint.

The magnetic paint-coated surface thus obtained was scratched under a load of 1 kg with a scratch tester stretched with highly rigid fibers (Kevlar yarn), and the scratches on the magnetic paint-coated surface were evaluated.

This evaluation method corresponds well to the abrasion (MAG scratch) of the magnetic surface after the application of the magnetic layer in the production of a magnetic tape.

<Judgment> ：: MAG is not peeled at all ：: MAG is slightly peeled △: MAG is considerably peeled ×: MAG is completely peeled

(8) Coatability The coating surface of the film provided with the easy-adhesion layer is visually observed, and the coating unevenness is evaluated.

<Judgment> ：: Almost no coating spots ：: Some coating spots Δ: Slightly high spots ×: Quite a lot of spots

[0075]

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

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 an average particle size of 0.6 μm as a lubricant
0.03% by weight of silicone resin particles and an average particle size of 0.
To the mixture was added 0.2% by weight of alumina particles of 15 μm θ-type crystals and polymerized by a conventional method to obtain polyethylene terephthalate having an intrinsic viscosity (orthochlorophenol, 35 ° C.) of 0.62.

The polyethylene terephthalate pellets were dried at 170 ° C. for 3 hours and then supplied to an extruder popper.
Melt at a melting temperature of 280-300 ° C, pass this molten polymer through a 1 mm slit die for surface finishing 0.3 s
Extruded on a rotating cooling drum with a surface temperature of 20 ° C.
An unstretched film of 050 μm was obtained.

The unstretched film thus obtained was preheated at 75 ° C., and further cooled between low-speed and high-speed rolls.
mm, heat it with an IR heater with a surface temperature of 900 ° C from above, stretch 3.7 times, cool rapidly, and copolymerize terephthalic acid, 5Na sulfoisophthalic acid (11 mol%), and ethylene glycol diethylene glycol. A composition comprising 100 parts by weight of a polyester resin (secondary transition point (Tg) = 70 ° C.), 50 parts by weight of colloidal silica having an average particle size of 80 nm, and 8 parts by weight of a polyoxyethylene nonyl phenyl ether having an HLB of 12.8. A water-based coating solution (solid content: 6.0 wt%) was applied to both surfaces of a uniaxially stretched film by a reverse coater so that the dry coating thickness after biaxial stretching was 60 nm (solid content conversion),
The film was stretched 3.8 times in the transverse direction at 5 ° C. The obtained biaxially stretched film was heat-set at a temperature of 220 ° C. for 5 seconds,
Thus, a biaxially oriented polyester film having a thickness of m was obtained. Table 1 shows the properties of this film.

[Examples 2 to 3, Comparative Examples 1 to 5] Example 1
Was changed to the lubricant particles shown in Tables 1 and 2,
Further, the particle (A) has an average particle diameter of 0.2 to 1.5 μm, the addition amount is in the range of 0.005 to 0.5 wt%, and the particle (B) has an average particle diameter of 0.02 to 0.3 μm. In the same manner as in Example 1 except that the addition amount was in the range of 0.05 to 1.0 wt%, and the surface roughness SRz of the obtained film was adjusted to the values shown in Tables 1 and 2. An axially-oriented adhesive polyester film was obtained. Tables 1 and 2 show the properties of these films.

[Examples 4 and 5, Comparative Examples 6 and 9] Example 1
Was obtained in the same manner as in Example 1 except that the resin composition shown in Tables 1 and 2 and the polyester resin adjusted to the secondary transition point were used instead of the aqueous polyester resin in Example 1. Tables 1 and 2 show the properties of these films.

Examples 6 and 7, Comparative Examples 10 and 15 Example 1 was repeated except that the average particle size, weight ratio, and coating thickness of the colloidal particles in Example 1 were set to the values shown in Tables 1 and 3.
In the same manner as in the above, a biaxially oriented easy-adhesive polyester film was obtained. The properties of these films are shown in Tables 1 and 3.

[0082]

[Table 1]

[0083]

[Table 2]

[0084]

[Table 3]

As is clear from these tables, the composition according to the present invention has excellent adhesiveness and blocking resistance, has excellent abrasion resistance, and has low chargeability. It is useful as a base film for recording media.

[0086]

The easily adhesive polyester film of the present invention has excellent adhesiveness, blocking resistance and abrasion resistance,
In addition, the film has characteristics of low chargeability, and particularly has excellent characteristics as a film for a magnetic recording medium.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a blade scraping evaluation device.

FIG. 2 is a schematic diagram of a metal pin scraping evaluation device.

FIG. 3 is a schematic view of an apparatus for measuring running frictional electrification with a metal pin.

[Description of Signs] 1 Unwinding reel 2 Tension controller 3, 5, 6, 8, 9, 11 Free roller 4 Tension detector (entrance) 7 Blade 7'SUS fixing pin 10 Tension detector (exit) 12 Guide roller 13 Take-up reel 14 Film surface electrometer

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Teruo Takahashi 3-37-19 Koyama, Sagamihara City, Kanagawa Prefecture Inside the Sagamihara Research Center, Teijin Limited (56) References JP-A-5-179032 (JP, A) Hei 5-84880 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 C08J 7/04

Claims (8)

(57) [Claims] 1. At least one surface of a biaxially oriented polyester film containing (A) heat-resistant polymer particles and (B) alumina particles and / or colloidal silica particles,
(C) 5-18 mol% (per total dicarboxylic acid component) of sulfonic acid groups in the molecule, and the secondary transition point is 50
An aqueous polyester resin having a mean particle size of 10 to 200 nm; and (D) an aqueous polyester resin having a mean particle size of 10 to 200 nm based on 100 parts by weight of the aqueous polyester. An easily adhesive polyester, wherein the thickness (nm) and the average particle size (nm) of the colloidal particles (D) satisfy the following formula (1), and the film has a surface roughness SRz of 50 to 500 nm. the film. 0.3 ≦ (thickness of coating layer / average particle size of colloid particles) ≦ 3.0３ (1) 2. The easily adhesive polyester film according to claim 1, wherein (A) the heat-resistant polymer particles are silicone resin particles. 3. The heat-resistant polymer particles (A) have an average particle diameter of 0.3 to 1.2 μm and a content of 0.005 to 0.005.
3. The easily adhesive polyester film according to claim 1, wherein the amount is 0.3% by weight. 4. The polyester film according to claim 1, wherein the (B) alumina particles are alumina particles of θ-type crystals. 5. The method according to claim 1, wherein (B) the alumina particles and / or the colloidal silica particles have an average particle size of 0.02 to 0.3 μm and a content of 0.05 to 1.0% by weight. 4. The easily adhesive polyester film according to 4. 6. The easily adhesive polyester film according to claim 1, wherein (D) the colloidal particles are colloidal silica. 7. The method according to claim 1, wherein (A) the heat-resistant polymer particles are silicone resin particles, (B) the alumina particles are θ-type alumina particles, and (D) the colloidal particles are colloidal silica. Easily adhesive polyester film. 8. The sulfonate group in the aqueous polyester resin (C) is ─SO ₃ M (where M represents a metal atom, an ammonium group or a quaternary amine in an equivalent amount to ─SO ₃ ).
The easily adhesive polyester film according to claim 1, which is a group represented by the formula: