JPH0664034A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To provide a polyester film wherein dispersibility and affinity of incorporated particles are improved. CONSTITUTION:The title film is a film prepd. by drawing a polyester contg. 0.01-3wt.% particles wherein the surface of a crosslinked polymer particle with a mean particle diameter of 0.01-3mum, a particle size distribution value (r) of at most 1.3 and a particle diameter ratio of 1.0-1.1 is treated with an aluminum oxide particle and the degree of deformation by drawing of the crosslinked polymer particle is 1.2-5.0.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biaxially oriented polyester film containing composite crosslinked polymer particles having improved dispersibility and affinity in polyester.

[0002]

2. Description of the Related Art Polyesters, particularly polyester films made from polyethylene terephthalate as raw materials, have been widely used as industrial materials because of their excellent physical and chemical properties. In each application, the preference for high grade has become remarkable, and it has been strongly desired that the film surface be uniform. Further, for example, it is desired to improve friction between the films or when the film and the base material are brought into contact with each other at a high speed, abrasion of the surface layer of the film due to abrasion, and generation of abrasion powder due to dropout of particles. Especially in magnetic recording applications where strict quality is required, it is necessary to satisfy these points to a high degree.

Conventionally, as a means for improving the running property, abrasion resistance and scratch resistance of a polyester film, a method of appropriately roughening the surface of the film has been known, and some improvements have been made. Not enough results have been obtained. For example, when using so-called precipitated particles from catalyst residues during polyester production as fine particles,
Since the precipitated particles are easily broken by stretching, the running property and wear resistance are poor, and it is difficult to recycle the precipitated particles.
When inert inorganic compound particles are added to polyesters such as silicon oxide, barium sulfate, titanium dioxide, and calcium phosphate, the particles are not broken or deformed by stretching, and relatively steep projections can be provided. You can
Although the runnability is improved, the particle size distribution is generally wide and particles easily fall off. Therefore, when it is used for a magnetic recording medium, for example, electromagnetic characteristics are often deteriorated and dropouts frequently occur. As described above, a polyester film satisfying a high level of surface uniformity, running property and abrasion resistance of the film has not been obtained so far.

[0004]

In view of the above situation, the inventors of the present invention have excellent running properties and abrasion resistance at the same time, and can sufficiently satisfy various properties required when the film is formed. As a result of intensive studies to provide a biaxially oriented polyester film, it is possible to satisfy the required properties by compounding a composite crosslinked polymer particle having a specific degree of deformation covered with a specific particle. That is, the present invention has been completed.

That is, the gist of the present invention is that the average particle size is 0.
0.01 to 3% by weight of particles obtained by treating the surface of crosslinked polymer particles having a particle size distribution value (r) of 1.3 to 3 μm and a particle size ratio of 1.0 to 1.1 with aluminum oxide particles. A biaxially oriented polyester film, which is a film obtained by stretching the contained polyester, wherein the degree of deformation of the crosslinked polymer particles due to the stretching is 1.2 to 5.0.

The present invention will be described in detail below. The polyester referred to in the present invention is a polyester obtained from an aromatic dicarboxylic acid or its ester and glycol as main starting materials, and has 80% of its repeating structural units.
Above are ethylene terephthalate units or ethylene-
Refers to polyesters having 2,6-naphthalate units. And, under the conditions that do not deviate from the above range,
You may contain the other 3rd component. Examples of the aromatic dicarboxylic acid component include terephthalic acid and 2,6-
Other than naphthalenedicarboxylic acid, for example, isophthalic acid, phthalic acid, adipic acid, sebacic acid, oxycarboxylic acid (for example, p-oxyethoxybenzoic acid, etc.) and the like can be used. As the glycol component, in addition to ethylene glycol, for example, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexane dimethanol, neopentyl glycol, etc., may be used alone or in combination of two or more. Can be used.

An important constituent of the present invention is the use of composite crosslinked polymer particles which are surface-treated with aluminum oxide particles as particles to be incorporated in polyester and which can be appropriately deformed by stretching. In the present invention, a crosslinked polymer particle having a particle size ratio before stretching of 1.0 to 1.1,
Deformation degree (as defined in Examples) is 1.2 to 5.0, preferably 1.2 to by applying stretching stress.
Composite crosslinked polymer particles having a ratio of 4.0, more preferably 1.5 to 3.0 are used. When the degree of deformation is less than 1.2, voids are generated at the interface between the particles and the polyester due to strong stress during stretching, and the particles are likely to fall off, which is not preferable. If the degree of deformation exceeds 5.0, the particles are excessively deformed and sharp projections cannot be formed on the film surface, which is not preferable.

The crosslinked polymer particles applicable to the present invention include one or more monovinyl compounds (A) having only one aliphatic unsaturated bond in the molecule and two or more monovinyl compounds as a crosslinking agent in the molecule. A compound having an aliphatic unsaturated bond (B)
The crosslinked polymer particles used in the present invention can be obtained by copolymerizing one or more of them with an emulsion polymerization method. The emulsion polymerization method as used herein refers to emulsion polymerization in a broad sense including concepts such as soap-free emulsion polymerization and seed emulsion polymerization. As the compound (A) used in the present invention, acrylic acid,
Methacrylic acid and alkyl or glycidyl esters thereof, maleic anhydride and its alkyl derivatives,
Examples thereof include vinyl glycidyl ether, vinyl acetate, styrene, and alkyl-substituted styrene. Examples of the compound (B) include divinylbenzene, divinyl sulfone, ethylene glycol dimethacrylate, 1,4 butanediol diacrylate and the like. One or more kinds of the compounds (A) and (B) are used, but a compound having a nitrogen atom or ethylene may be copolymerized. In that case, hydrogen peroxide, potassium persulfate, potassium persulfate-sodium thiosulfate, or the like can be used as the polymerization initiator.

As a dispersion aid during the polymerization of crosslinked polymer particles, a fatty acid salt, an alkyl sulfate ester salt, an alkylbenzene sulfonate, an alkylsulfosuccinate, an alkylnaphthalene sulfonate, an alkyl diphenyl ether disulfonate, an alkyl phosphate, Anionic surfactant such as polyoxyethylene alkyl or alkylallyl sulfate ester salt, polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethylene derivative, polyoxyethylene-oxypropylene block copolymer, sorbitan fatty acid ester, Nonionic surfactants such as polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, etc. and alkylamine salts, 4th Cationic surfactants and alkyl betaines such as ammonium salts, amphoteric surfactants such as amine oxides. Among them, anionic surfactants typified by alkyldiphenyl ether disulfonate are preferably used. A surfactant is preferable since it prevents aggregation of particles and improves dispersibility when the particles are blended with polyester.

The amount of the surfactant based on the crosslinked polymer particles is usually 0.001 to 0.20% (relative to particles), preferably 0.005 to 0.15%. This value is 0.001%
If it is less than the above range, the dispersibility in polyester may be poor.
Further, if it exceeds 0.20%, coarse foreign matter may be generated due to the surfactant. In any case, the crosslinked polymer particles used in the present invention have a crosslinked structure and are substantially insoluble even at high temperatures during the production or molding of polyester,
It is infusible and has heat resistance. Specifically, the weight loss rate after heat treatment at 300 ° C. for 30 minutes under nitrogen gas flow is usually 30% by weight or less, preferably 20% by weight or less. Further, in the present invention, it is necessary to select the composition so as to obtain easily deformable property. For that purpose, the glass transition temperature of the crosslinked polymer particles is lowered, for example, 95 ° C. or lower, preferably 85 ° C. The copolymerization component, especially the compound (A), is selected. Specifically, it is preferable to introduce a compound having a glass transition temperature of 0 ° C. or lower when a polymer is obtained only from the copolymerization component.
Examples of such a compound include, but are not limited to, an alkyl ester of acrylic acid having 2 to 4 carbon atoms and an alkyl ester of methacrylic acid having 6 to 12 carbon atoms.

Further, the degree of cross-linking has a great influence on the easy deformability, but in the present invention, it is preferable that the degree of cross-linking is relatively low within the range where heat resistance is allowed. Specifically, the weight ratio of the component (B) in the copolymer is 0.5 to 20%, preferably 1 to 15%. The average particle size of the crosslinked polymer particles used in the present invention is 0.01 to 3 μm, preferably 0.1 to 2 μm. If the average particle size is less than 0.01 μm, the running property and abrasion resistance of the film are insufficient. On the other hand, if the thickness exceeds 3 μm, the surface roughness becomes too large, and for example, for magnetic recording media, the electrical characteristics deteriorate, and for capacitor dielectrics, the withstand voltage characteristics deteriorate. In the present invention, the particle size distribution value (r) of the crosslinked polymer particles is 1.3 or less, preferably 1.2 or less, more preferably 1.1 or less. If this value exceeds 1.3, a uniform film surface cannot be obtained, which is not preferable.

The crosslinked polymer particles to be used may or may not be porous, but it is preferable that the particles are porous because they are more compatible with polyester. The greatest feature of the present invention is that composite crosslinked polymer particles obtained by surface-treating the above crosslinked polymer particles with aluminum oxide particles are used. When the crosslinked polymer particles are used alone, the particles often aggregate, especially when the functional group density of the particles is low or when the amount of the polyester compounded is large. This is particularly remarkable when the stirring strength during polyester polymerization is weak. However, when the composite crosslinked polymer particles surface-treated with such specific inorganic particles are used, not only the dispersibility in polyester can be significantly improved, but also the polyester film containing the particles has scratch resistance. Enjoy the unexpected effect of being improved.

The method for producing the aluminum oxide particles used in the present invention is, for example, a thermal decomposition method, that is, a method of flame hydrolysis using anhydrous aluminum chloride as a raw material, or an ammonium alum thermal decomposition method, that is, a method of using aluminum hydroxide as a raw material and sulfuric acid. And aluminum sulphate, followed by reaction with ammonium sulphate and baking as alum. The crystal form of aluminum oxide obtained by these methods is γ
Type or δ type is preferable, and δ type is more preferable. The primary particle size of aluminum oxide is usually in the range of 5 to 40 nm, but since it often forms agglomerates of more than 0.5 μm, it is desirable to appropriately crush and use it. The average particle size of the secondary aggregate of the aluminum oxide particles for surface-treating the crosslinked polymer particles of the present invention is preferably smaller than the average particle size of the crosslinked polymer particles, specifically 1 /
It is preferably 2 or less, more preferably ⅕ or less, particularly preferably 1/10 or less, and the average particle size is 0.03 to 0.2 μm, preferably 0.03 to 0.1 μm.
m. If the average particle size of the secondary aggregate of aluminum oxide particles exceeds 0.2 μm, the effect of improving dispersibility during polyester polymerization may be insufficient.

The amount of aluminum oxide particles used is preferably 0.1 to 2 times, more preferably 0.3 to 1 times the weight of the crosslinked polymer particles. If this value is less than 0.1 times, it tends to be difficult to improve the dispersibility. Further, even if this value exceeds the double amount, the dispersibility is no longer improved, and the slittability of the film may be deteriorated due to the aluminum oxide particles. As a method of treating the surface of the crosslinked polymer particles with aluminum oxide particles,
For example, when the zeta potential value of the crosslinked polymer particles dispersed in the aqueous solution is negatively (−) charged, an aqueous solution of aluminum oxide particles having a positive zeta potential value in the aqueous solution (+) is added, Examples include a method of treating for 3 to 5 hours with stirring,
By such treatment, the surface of the crosslinked polymer particles is covered with aluminum oxide particles.

In the present invention, the compounding amount of the composite crosslinked polymer particles surface-treated with aluminum oxide particles in the polyester is 0.01 to 3% by weight, preferably 0.0
It is 5 to 2% by weight. If the blending amount is less than 0.01% by weight, the slipperiness and abrasion resistance of the film are insufficient, and conversely 3
If the content is more than weight%, the surface roughness of the film becomes too large and the electromagnetic characteristics deteriorate, which is not preferable. As described above, in the present invention, a specific composite cross-linked polymer particle is used, but the effect can be particularly remarkably exhibited when the following requirements are combined. First, in the case of a film containing 80 mol% or more of ethylene terephthalate units, the refractive index in the thickness direction of the film containing the particles is 1.4.
It is to be 92 or more. ． When the refractive index in the thickness direction of the film is 1.492 or more, the effect of improving slipperiness and abrasion resistance becomes remarkable, and the adhesiveness to the magnetic layer can be improved, which is preferable. Such a refractive index is preferably 1.494 to 1.505. In the case of sequential biaxial stretching, the film having such physical properties has a longitudinal stretching temperature of 85 to 115 ° C. which is higher than the normal stretching temperature by 5 to 30 ° C.
It can be obtained by setting the degree.

The refractive index (n_TD) And the longitudinal direction
Refractive index of (n_MD) And (Δn; n _TD-N_MD) Is 0.0
When it is 10 or more, the cutting property is particularly excellent and the magnetic tape base is excellent.
-Suitable as a film. Cutability mentioned above
When slitting a magnetic tape with a shear cutter, etc.
If the cutting property is poor, the cut end will be streaky.
Turns up, or mustache or powder is generated from the cut end.
It When such a phenomenon occurs, white powder adheres to the tape,
Deteriorate electromagnetic conversion characteristics or induce dropout
It Δn is preferably 0.020 or more, more preferably
0.025 or more, particularly preferably 0.035 or more
is there. If Δn is too large, heat shrinkage etc.
Therefore, the upper limit of Δn is 0.060.
It is preferable that Furthermore, polyester film
The intrinsic viscosity of 0.52 to 0.62 is preferable,
4-0.59 is more preferable. When in this range,
The cuttability of the film and the productivity of the film are improved.

The second combination in which the effects of the present invention are particularly exerted is, in the case of a film containing 80 mol% or more of ethylene terephthalate units, the sum of the Young's modulus in the machine direction and the Young's modulus in the cross direction. 900 kg / mm ² or more, preferably 1000 kg / mm ² or more, more preferably 1
This is the case of 100 kg / mm ² or more. Usually, when strongly stretched to have a high strength like this, the particles easily fall off from the film surface layer and wear resistance deteriorates, but when the particles of the present invention are used, such a particle falling phenomenon is significantly reduced. Be improved. In addition, such a high-strength film can be obtained by, for example, the following film forming method. 2. A substantially non-oriented unstretched sheet is longitudinally stretched at 80 ° C to 120 ° C.
It is a method of stretching 0 to 6.0 times, then 3.0 to 6.0 times in the transverse direction, and heat treating at 170 to 240 ° C. Of course, after biaxial stretching in the longitudinal and transverse directions or simultaneous biaxial stretching, 1.05 to 1.05 in the longitudinal direction at a temperature of 110 ° C to 180 ° C.
A method of performing heat treatment after performing re-stretching 2.5 times can also be adopted. At this time, a method such as heat setting before re-longitudinal stretching, longitudinal relaxation after re-longitudinal stretching, or before or after re-longitudinal stretching and fine stretching in the longitudinal direction can be appropriately adopted. Further, re-stretching may be performed in the transverse direction as well.

The third combination in which the effects of the present invention are particularly exerted is when the composite crosslinked polymer particles are blended with a film containing 80 mol% or more of polyethylene-2,6-naphthalate units. 80% by mole of polyethylene-2,6-naphthalate units among polyester films
Films containing the above have attracted attention because they are excellent in mechanical strength and heat resistance, but since the film is often used under more severe conditions in terms of running speed and tension of the film, abrasion resistance is particularly high. Improvement is desired.
In particular, the sum of the Young's modulus in the machine direction and the Young's modulus in the cross direction of such a film containing the particles is 1300 kg / mm ² or more,
When it is more preferably 1400 kg / mm ² or more, and particularly preferably 1500 kg / mm ² or more, the effect of improving the abrasion resistance is remarkable. In the case of polyethylene-2,6-naphthalate, such a high-strength film can be obtained by the same method as for polyethylene terephthalate except that the stretching temperature is increased. A substantially non-oriented unstretched sheet at 90 ° C. to 180 ° C. in the machine direction of 3.0 to 6.0.
Double, and then stretched 3.0 to 6.0 times in the transverse direction, 180 ° C
This is a method of heat treatment at 260 ° C. Of course, after sequential biaxial stretching in the longitudinal and transverse directions or simultaneous biaxial stretching,
A method of re-stretching 1.05 to 4.0 times in the machine direction at a temperature of 0 ° C. to 200 ° C. and then heat treating can also be adopted. On this occasion,
Techniques such as heat setting before re-longitudinal stretching, longitudinal relaxation after re-longitudinal stretching, and fine magnification longitudinal stretching before or after re-longitudinal stretching can also be appropriately adopted. Further, re-stretching may be performed in the transverse direction as well.

As described above, in the present invention, by using a specific amount of the specific composite crosslinked polymer particles,
The properties of the polyester film can be improved, but the effects can be made more remarkable in the above three cases. In the present invention, it is possible to further improve the running property and abrasion resistance of the film by using one or more kinds of other particles in combination within a range not exceeding the gist thereof. Precipitated particles can be mentioned as one of such particles. The term "precipitated particles" as used herein refers to particles that are precipitated in the reaction system by polymerizing a system using an alkali metal or alkaline earth metal compound as a transesterification catalyst by a conventional method. Alternatively, terephthalic acid may be added during the transesterification reaction or polycondensation reaction to cause precipitation. In these cases, one or more phosphorous compounds such as phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, ethyl acid phosphate, phosphorous acid, trimethyl phosphite, triethyl phosphite, and tributyl phosphite are used. May be present. In addition, the inert substance particles can be deposited by these methods even when the esterification step is performed. For example, before or after the completion of the esterification reaction, an alkali metal or alkaline earth metal compound is present,
The polycondensation reaction is carried out in the presence or absence of a phosphorus compound. In any case, the precipitated particles referred to in the present invention contain one or more elements such as calcium, lithium, antimony and phosphorus.

Additive particles can also be used as one of the particles used in combination. The term "added particles" as used herein refers to particles added to the polyester from the outside, and specifically, kaolin, talc, carbon black, molybdenum sulfide,
Examples thereof include gypsum, aluminum oxide, barium sulfate, lithium fluoride, calcium fluoride, zeolite, calcium phosphate, silicon dioxide and titanium dioxide. When the average particle size of the particles used in the present invention is larger than the average particle size of the composite crosslinked polymer particles of the present invention, the amount is preferably equal to or less than that of the crosslinked polymer particles.
005 to 0.5 times the weight is more preferable, and 0.01 to
A weight of 0.3 times is particularly preferable. On the other hand, when the average particle size is smaller than the average particle size of the composite crosslinked polymer particles of the present invention, the same amount or more as the crosslinked polymer particles is preferable, and 1 to 20.
Double weight is more preferable.

Further, in the present invention, two or more kinds of composite crosslinked polymer particles having different average particle diameters may be used. In particular, it is a further preferred embodiment to combine the crosslinked polymer particles of large particles and the crosslinked polymer particles of small particles for the purpose of improving winding characteristics and running properties. Here, the crosslinked polymer particles of large particles refer to those having an average particle size of 0.5 to 2 μm, and the content thereof is particularly preferably 0.005 to 0.15% by weight, while the crosslinked polymer particles of small particles are used. The particles refer to those having an average particle size of 0.10 to 0.8 μm and a content of 0.2.
0 to 3.0% by weight is particularly preferred.

In the production of the polyester containing the specific composite crosslinked polymer particles of the present invention, the particles and the additive particles used in combination are preferably added during the polyester synthesis reaction. Particularly, it is preferably added after the completion of the transesterification reaction or the esterification reaction and before the start of the polycondensation reaction. The particles to be added are usually added as a slurry of ethylene glycol, but they may be subjected to treatments such as crushing, dispersion, classification and filtration in advance, if necessary.
The concentration of the slurry in the added ethylene glycol is 5 to 5
The amount is 0% by weight, preferably 10 to 40%. When the particle concentration of the slurry is less than 3% by weight, the amount of ethylene glycol used increases and the basic unit of ethylene glycol increases. Further, when a slurry having a particle concentration of more than 50% by weight is added, the dispersibility of particles tends to deteriorate.
As the polycondensation reaction catalyst for polyester synthesis, S
Commonly used catalysts such as b, Ti, Ge, Sn and Si compounds are used.

The film of the present invention, which is particularly suitable for magnetic recording media, can be obtained for the first time by the combination of specific particles and specific film physical properties. The film surface roughness is the center line average roughness (Ra). Is usually 0.00
5 to 0.1 μm, preferably 0.007 to 0.08 μm, and more preferably 0.01 to 0.03 μm. Further, the ratio (Rt / Ra) of the maximum protrusion height (Rt) to the center line average roughness (Ra) of the film of the present invention is preferably 15 or less, more preferably 12 or less, and more preferably 5 or more. Particularly preferred is 10 or less. Rt / Ra value is 1
When it exceeds 5, the uniformity of the base film surface tends to be poor, and the running property or abrasion resistance may be poor. Further, the film of the present invention may be a single layer or a laminated film of two or more layers as long as it satisfies the constituent requirements of the present invention. The film of the present invention is used not only as a base film for videotape but also for audio and floppy.
It can also be particularly effective when used as that for a disc. Of course, if necessary, for the dielectric of the capacitor,
It can also be used for packaging, plate making, and other purposes.

[0024]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. The measuring methods and definitions of various physical properties and characteristics in the examples are as follows. In Examples and Comparative Examples, “part” means “part by weight”.

(1) Average particle size and particle size distribution value The particle size with an integrated volume fraction of 50% in the equivalent spherical distribution measured with an electron microscope was taken as the average particle size. The particle size distribution value (r) was calculated from the following formula. Particle size distribution value (r) = d ₂₅ / d ₇₅ (In the above formula, d ₂₅ and d ₇₅ are the cumulative volume of the particle group measured from the large particle side, and the particle size corresponds to 25% and 75% of the total volume, respectively. (2) Mean particle size of secondary agglomerate Centrifugal sedimentation particle size distribution analyzer manufactured by Shimadzu (SA-CP)
Equivalent spherical distribution measured by type 3) 5
The particle size of 0% was taken as the average particle size. (3) Weight reduction rate Using a thermal analyzer DT-20Bs manufactured by Shimadzu Corporation, under nitrogen gas flow (200 ml / min), from room temperature to 300 ° C at a heating rate of 10 ° C / min, 300 ° C-30 min. The weight reduction rate after the holding was determined.

(4) Glass transition temperature Differential scanning calorimeter (DSC-Thermal Analy manufactured by DuPont
st 200 type) was used, and the glass transition temperature was defined as the starting point of the change in the amount of heat of the DSC curve when the temperature was raised at a rate of 16 ° C./min. (5) Particle size ratio The particles blended in the polyester were observed with a scanning electron microscope, and the maximum diameter and the minimum diameter were calculated for each particle and the ratio was calculated. This value was obtained for at least 100 particles and the arithmetic mean was used as the degree of deformation. (6) Deformation degree A small piece of film was fixedly molded with an epoxy resin and then cut with a microtome, and the cross section in the longitudinal direction of the film was observed. With respect to the particles existing within 5 μm from the film surface, the maximum diameter and the minimum diameter were obtained for each particle and the ratio thereof was calculated.
This value was obtained for at least 100 particles and the arithmetic mean was used as the degree of deformation.

(7) Zeta potential of particles Using a zeta potential measuring device (ELS-800 type, manufactured by Otsuka Electronics Co., Ltd.), particles were added to pure water to prepare a dilute slurry, which was measured by a usual electrophoresis method. (8) Apparent average particle size and particle dispersibility of cross-linked polymer particles in the polymer The polymer is cut into ultra-thin sections of about 800 Å with an ultra-thin film preparation device, and then observed with a transmission electron microscope to obtain the average particle size. The diameter was calculated. The particle dispersibility was determined as follows. ◯: Almost no secondary aggregated particles were observed and the purpose was achieved. Δ: Slight secondary aggregation exists and the purpose is not achieved. X: Most of the particles are secondary agglomerated particles and do not achieve the purpose. (9) Intrinsic Viscosity of Film Polymer-1 g in phenol / tetrachloroethane = 50
Dissolve in 100 ml of a mixed solvent of 50/50 (weight ratio) and
It was measured at 0 ° C.

(10) Refractive Index of Film Using an Abbe refractometer manufactured by Atago Optical Co., Ltd., the refractive index in the thickness direction (nα), the refractive index in the width direction (n _TD ) and the refractive index in the longitudinal direction (n) are used. _MD ) was measured. The refractive index was measured using sodium D line. (11) Young's modulus (tensile modulus) manufactured by Intesco Co., Ltd. Tensile tester Intesco Model 20
Using the 01 type, a sample film having a length of 300 mm and a width of 20 mm was pulled at a strain rate of 10% / min in a room adjusted to a temperature of 23 ° C. and a humidity of 50% RH, and the initial tensile stress-strain curve was obtained. Young's modulus (E) was calculated by the following equation using the linear portion. E = Δσ / Δε (where E, Δσ, and Δε are Young's modulus (kg
/ Mm ² ), the stress difference due to the original average cross-sectional area between two points on the straight line, and the strain difference between the same two points) (12) Average roughness of film surface and uniformity of roughness Japanese Industrial Standard JIS According to the method described in B0601, a surface roughness measuring device (SE- manufactured by Kosaka Laboratory Ltd.)
3F) was used to determine the centerline average roughness (Ra) and maximum height (Rt). The radius of the stylus used was 2.
0 μm, load is 30 mg, cutoff value is 0.0
It is 8 mm. The smaller Rt / Ra, the more uniform the surface.

(13) Runnability It was evaluated by the slip property of the film. The slidability is 53 g (T) when the film is wound around a fixed hard chrome-plated metal roll (diameter 6 mm) at an angle (θ) of 135 °.
The load of ₂ ) was applied to one end and run at a speed of 1 m / min, the resistance force (T ₁ , g) at the other end was measured, and the friction coefficient (μd) during running was determined by the following formula. _{μd = 0.424 · ln (T 1} /53) (14) Aluminum was deposited on the coarse protrusions number film surface, using a Nikon Opti photo interference microscope, was measured by double beam method. The measurement wavelength was 0.54 μm, and the number of projections (projection height of 0.81 μm or more) showing interference fringes of the third order or more was measured over an area of 100 cm ² to obtain the number of coarse projections. (15) Affinity By exposing the periphery of the composite crosslinked polymer particles in the film according to the method of the above (6), the major axis of at least 100 particles and the major axis of voids around the particles are measured, and The average value of the ratio (major axis of void / major axis of composite crosslinked polymer particles) was evaluated according to the following three-stage criteria. ◯: Void ratio ≦ 0.50 or less Δ: 0.51 ≦ void ratio ≦ 1.00 ×: void ratio ≧ 1.01

(16) Wear characteristics Fixed pin made of hard chrome with a diameter of 6 mm (material SU
S420-J2, finishing 0.2S), wrap a film with a width of 10mm and contact it at an angle of 135 °, the speed is 11.4.
A film of 200 m was run over a total of 5000 m at m / min and an initial tension of 300 g, the amount of abrasion white powder adhering to the pins was visually evaluated, and evaluation was performed for each rank shown below. Rank A: No adhesion Rank B: Small amount adhesion Rank C: Small amount (more than Rank B) adhesion Rank D: Very much adhesion (17) Film winding characteristics Roll during polyester film winding operation The overall judgment was good or bad such as winding deviation, wrinkles and winding appearance.

(18) Magnetic Tape Characteristics First, a magnetic tape was manufactured. That is, the magnetic fine powder 20
0 parts, polyurethane resin 30 parts, nitrocellulose 10
Parts, vinyl chloride-cellulose acetate copolymer 10 parts, lecithin 5 parts, cyclohexanone 100 parts, methyl isobutyl ketone 100 parts, and methyl ethyl ketone 300 parts are mixed and dispersed in a ball mill for 48 hours, and then 5 parts of polyisocyanate compound is added to the magnetic paint. After applying this to a polyester film, the coating was magnetically oriented before the coating was sufficiently dried and solidified, and then dried to form a magnetic layer having a thickness of 2 μm. Then, this coated film was rolled using a five-step super calender composed of a mirror-finished metal roll and a polyester-based composite resin roll, with a roll temperature of 85 ° C. and a linear pressure of 250 kg / cm, traveling speed 80 m / mi
Under the condition of n, it was repeatedly run 7 times over 5000 m, the amount of white powder adhering to the resin roll was visually evaluated, and the evaluation was performed according to the ranks shown below. ○: Almost no white powder adhered to the resin roll △: Very slight white powder adhered ×: Obvious white powder adhered Next, the calendered tape was slit into a 1/2 inch width After that, the following magnetic tape characteristics were evaluated at a constant speed with an NV-3700 type video deck manufactured by Matsushita Electric.

(I) Electromagnetic conversion characteristics (VTR head output) The VTR head output at a measurement frequency of 4 MHz was measured with a synchroscope, and compared with a reference tape, and evaluated according to the ranks shown below. ⊚: very good than standard tape 〇: equivalent to standard tape △: inferior to standard tape ×: obviously inferior to standard tape and unusable for practical use (II) maximum dropout number A video tape on which a signal of 4.4 MHz was recorded was reproduced, and the number of dropouts was measured by a dropout counter of Okura Industry Co., Ltd. for about 20 minutes and converted into the number of dropouts per minute. The measurement was repeated 20 times, and the maximum converted value was taken as the maximum number of dropouts.

(19) Scratch resistance A magnetic tape slit to a width of 1/2 inch has a diameter of 6 mm.
Wrap the film around the hard chrome plated metal pin (finish 3S) of 135 °, traveling speed 3m / sec, tension 5
The base film surface of the magnetic tape was rubbed once with 0 g. Next, aluminum was vacuum-deposited on the abraded surface to a thickness of about 1000Å, and the amount of scratches was visually observed, and the following judgment was made. Rank 1: Extremely large amount of scratches Rank 2: Large amount of scratches Rank 3: Intermediate amount of scratches 2, 4 Rank 4: Small amount of scratches Rank 5: No scratches

Example 1 [Production of composite crosslinked polymer particles] 1500 parts by weight of demineralized water, 3.2 parts by weight of water-soluble polymerization initiator potassium persulfate, and sodium lauryl sulfate as a dispersion stabilizer (trade name: Emer-
0.06 parts by weight of the product (L0 Kao Co., Ltd.) was added and uniformly dissolved, and then a mixed solution of 70 parts by weight of ethylene glycol monomethacrylate, 20 parts by weight of n-butyl acrylate and 10 parts by weight of divinylbenzene was added.
Then, the polymerization reaction was carried out at 70 ° C. for 12 hours while stirring in a nitrogen gas atmosphere. The reaction rate was 98%, the average particle size of the particles obtained was 0.50 μm, and the particle size distribution value (r) was 1.2.
3, the weight loss rate is 5.2%, the glass transition temperature is 112
C., the particle size ratio was 1.03. The zeta potential of the obtained particles was -20 mV, and the pH at that time was 6.0. When the obtained particles were observed with an electron microscope, they were almost spherical.

Then, 50 parts by weight of δ-type alumina particles having a primary particle size of 0.02 μm are added to 500 parts by weight of demineralized water and dispersed by a homomixer, and then 0.5 part by weight of ethyl acid phosphate is added to adjust the pH to 5.0. The mixture was crushed and crushed with a sand grinder to obtain a particle-containing water slurry. The average secondary particle diameter of the particles was 0.06 μm, and the zeta potential was +30 mV. Next, 1600 parts by weight of the above-mentioned cross-linked polymer particle-containing water slurry and 550 parts by weight of δ-type alumina particle-containing water slurry were added and kept under stirring for -4 hours to coat the surface of the cross-linked polymer particles with δ-type alumina particles. . Further, 1500 parts of ethylene glycol was added, and water was distilled off under heating and reduced pressure to obtain an ethylene glycol slurry.

[Production of Polyester] 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol and 0.09 part of magnesium acetate tetrahydrate are placed in a reactor, heated and heated to distill off methanol to carry out a transesterification reaction. It took 4 hours from the start to raise the temperature to 230 ° C. to substantially end the transesterification reaction. Then, 4 parts of the above slurry was added. After the slurry was added, 0.03 part of phosphoric acid and 0.04 part of antimony trioxide were further added to obtain 4
A polycondensation reaction was performed for a time to obtain polyethylene terephthalate having an intrinsic viscosity of 0.61. When the particles in the polymer were observed by a transmission electron microscope, it was observed that the δ-type alumina particles were coated on the surface layer of the crosslinked polymer particles,
The dispersibility of the particles was extremely good. The apparent average particle size of the particles was 0.55 μm. Then, the obtained polyester is dried and melt-extruded at 290 ° C.,
Amorphous sheet is obtained, 93 in the sheet flow direction (vertical direction)
Stretched 3.5 times at ℃ and 3.5 times at 110 ℃ in the transverse direction,
Heat treatment was performed at 20 ° C. for 3 seconds to obtain a film having a thickness of 15 μm. The Young's modulus of the obtained film is 43 in the longitudinal direction.
0 kg / mm ^2, the transverse direction was 440 kg / mm ^2. The intrinsic viscosity of the film was 0.59. A magnetic layer was applied to the obtained film to obtain a magnetic tape, and its characteristics were measured.

Example 2 Using the crosslinked polymer particles coated with δ-type alumina particles used in Example 1, the refractive index in the thickness direction of the film was 1.4.
A film was obtained in the same manner as in Example 1 except that 90 was used.
Its characteristics were evaluated.

Example 3 A film was obtained in the same manner as in Example 1 except that the crosslinked polymer particles coated with δ-type alumina particles used in Example 1 were used and the birefringence of the film was set to 0.006. , Its characteristics were evaluated.

Comparative Example 1 A film was obtained in the same manner as in Example 1 except that the δ-type alumina particles were not used in the production of the crosslinked polymer particles of Example 1, and the characteristics thereof were evaluated. Comparative Example 2 A film was obtained in the same manner as in Example 1 except that fine silica particles were used in place of the δ-type alumina particles in the production of the crosslinked polymer particles of Example 1, and the characteristics thereof were evaluated. Comparative Example 3 In Example 1, the composition of the crosslinked polymer particles was changed to 70 parts by weight of ethylene glycol monomethacrylate and 20 parts of styrene.
A film was obtained in the same manner as in Example 1 except that the amount was 10 parts by weight and the amount of divinylbenzene was 10 parts by weight, and the characteristics thereof were evaluated. Example 4 After using the crosslinked polymer particles used in Example 1 and stretching in the longitudinal and transverse directions in the same manner as in the film production of Example 1, 13
The film was stretched 1.08 times in the machine direction at 0 ° C. to obtain a film reinforced in the machine direction and having a thickness of 9.8 μm, and its characteristics were evaluated.

Example 5 The transesterification reaction was carried out in the same manner as in Example 1 except that dimethyl-2,6-dimethylnaphthalate was used in place of dimethyl terephthalate in the production of the polyester of Example 1. It was Then, 4 parts of ethylene glycol slurry containing crosslinked polymer particles coated with δ-type alumina particles used in Example 1 was added, and phosphoric acid 0.03 was further added.
And 0.04 part of antimony trioxide were added and polycondensation reaction was carried out by a conventional method to obtain polyethylene having an intrinsic viscosity of 0.59.
2,6-naphthalate was obtained. Then the obtained polymer
Was solid-state polymerized at 0.3 mmHg and 235 ° C. for 7 hours to obtain polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.68. The polymer was extruded into a sheet at 295 ° C. from an extruder, and an amorphous sheet having a thickness of 100 μm was obtained by the electrostatic cooling method. Next, at 140 ℃ 4.2 times in the vertical direction,
After stretching 3.9 times in the transverse direction with a tenter, 5 at 220 ° C
Heat treatment is performed for 2 seconds and a thickness of 8 μm polyethylene-2,6
-A naphthalate film was obtained and its properties were evaluated.

Example 6 Using the particles used in Example 5, Young's modulus in the longitudinal direction was 10
A polyethylene-2,6-naphthalate film was obtained in the same manner as in Example 5 except that the amount was 10 kg / mm ^2, and its characteristics were evaluated. The results obtained above are summarized in Table 1 below.
~ 3.

[0042]

[Table 1] In Table 1 above, EGMM represents ethylene glycol monomethacrylate, ST represents styrene, n-BA represents n-butyl acrylate, and DVB represents divinylbenzene.

[0043]

[Table 2]

[0044]

[Table 3]

The films of Examples 1 to 7 satisfying the requirements of the present invention all have a uniform film surface and have good runnability,
It has excellent wear resistance. In particular, a film containing fine aluminum oxide particles is also excellent in scratch resistance and is suitable as a base film for magnetic recording media.

[0046]

The film of the present invention has a uniform and fine surface structure, is particularly excellent in abrasion resistance and running property, and is useful as an industrial material such as a base film for magnetic recording media. Yes, its industrial value is high.

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Claims (1)

[Claims] 1. A surface of cross-linked polymer particles having an average particle size of 0.01 to 3 μm, a particle size distribution value (r) of 1.3 or less, and a particle size ratio of 1.0 to 1.1 is aluminum oxide particles. A film obtained by stretching a polyester containing 0.01 to 3% by weight of treated particles, wherein the degree of deformation of the crosslinked polymer particles by stretching is 1.2 to 5.0. Biaxially oriented polyester film.