JPH0625440A - Biaxially oriented polyester film - Google Patents

Abstract

PURPOSE:To obtain the subject film improved in traveling properties and abrasion resistance by adding crosslinked polymer particles having a specified mean particle diameter and a specified surfactant coverage. CONSTITUTION:This film is one containing 0.01-3wt.% crosslinked polymer particles having a mean particle diameter of 0.01-3mum and a surfactant coverage as defined by the equation (wherein the surfactant coverage (%) is the area (m<2>/g) of the crosslinked polymer particles covered by the surfactant, and the specific surface area (m<2>/g) of the crosslinked polymer particles is one measured by the BET method) of 5% or above. The crosslinked polymer which can be applied can be obtained by the emulsion copolymerization of a monovinyl compound containing only one aliphatic unsaturation in the molecule (e.g. acrylic acid) with a crosslinking compound containing at least two aliphatic unsaturations in the molecule (e.g. divinylbenzene) in the presence of a surfactant.

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 crosslinked polymer particles having improved dispersibility 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 the application, the high-class orientation became remarkable, and it was strongly desired that the film surface be uniform. Further, there is a long-awaited demand for improvement in wear characteristics, and it is necessary to satisfy these points to a high degree particularly in magnetic recording applications where strict quality is required. Conventionally, as a means for improving the running property and abrasion resistance of a polyester film, a method in which particles are contained in the film and the surface thereof is appropriately roughened is known, and some improvement has been made. , But not enough results have been obtained. For example, when so-called precipitated particles are used as particles from a catalyst residue at the time of polyester production, the precipitated particles are easily broken by stretching, so that the running property and abrasion resistance are poor, and the recycling is difficult. 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. However, when used as a magnetic recording medium, for example, deterioration of electromagnetic conversion characteristics and frequent occurrence of dropouts often occur because the particle size distribution of these particles is wide and particles are likely to fall off. Cause it.

In order to overcome these problems, it has been proposed to use organic crosslinked polymer fine particles having an excellent affinity with polyester. However, in general, organic crosslinked polymer fine particles have poor heat resistance and are easily softened during polyester polymerization or melt molding, and due to these, they do not always show good dispersibility in polyester and often aggregate to behave as coarse particles. As in the case of the above-mentioned inorganic particles, when used for a magnetic recording medium, for example,
This often causes deterioration of electromagnetic conversion characteristics and frequent dropouts. 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]

SUMMARY OF THE INVENTION In view of such circumstances, the inventors of the present invention have at the same time highly satisfied running property and wear resistance,
As a result of extensive studies to provide an excellent biaxially oriented polyester film that can sufficiently satisfy various properties required as a film, if certain specific crosslinked polymer particles are blended, it is necessary to satisfy such required properties. The present invention has been completed and the present invention has been completed. That is, the gist of the present invention comprises 0.01 to 3% by weight of crosslinked polymer particles having an average particle size of 0.01 to 3 μm and a coverage of a surfactant defined by the following formula of 5% or more. It exists in a biaxially oriented polyester film.

[0005]

[Equation 2] [In the above formula, the area occupied by the surfactant is the area occupied by the surfactant (m ² / g) on the surface of the crosslinked polymer particles, and the specific surface area is BET.
Represents the specific surface area (m ² / g) of the crosslinked polymer particles measured by the method]

The present invention will be described in detail below. The polyester referred to in the present invention is a polyester obtained by using aromatic dicarboxylic acid or its ester and glycol as main starting materials, and 80% or more of repeating structural units are ethylene terephthalate units or ethylene-2,6.
-Refers to polyesters with naphthalate units. Then, the other third component may be contained under the condition not deviating from the above range. As the aromatic dicarboxylic acid component,
For example, in addition to terephthalic acid and 2,6-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 a glycol component, other than ethylene glycol,
For example, diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol or the like may be used alone or in combination of two or more.

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 (A) as a crosslinking agent in the molecule. The crosslinked polymer particles used in the present invention can be obtained by copolymerizing one or more compounds having an aliphatic unsaturated bond (B) with an emulsion polymerization method in the presence of a specific amount of a surfactant. The emulsion polymerization method here refers to emulsion polymerization in a broad sense that also includes the concept of seed emulsion polymerization and the like. Examples of the compound (A) used in the present invention include acrylic acid, methacrylic acid and their alkyl or glycidyl esters, maleic anhydride and its alkyl derivatives, vinyl glycidyl ether, vinyl acetate, styrene, and alkyl-substituted styrene. You can
Further, as the compound (B), divinylbenzene, divinyl sulfone, ethylene glycol dimethacrylate,
1,4 butanediol diacrylate etc. can be mentioned. One or more kinds of the compounds (A) and (B) are used, but a compound having a nitrogen atom or ethylene may be copolymerized.

Surfactants for coating the crosslinked polymer particles used in the present invention include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylsulfosuccinates, alkylnaphthalene sulfonates, alkyldiphenyl ether disulfonates, Anionic surfactants such as alkyl phosphates, polyoxyethylene alkyl or alkylallyl sulfate ester salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene derivatives, polyoxyethylene-oxypropylene block copolymers , Nonionic surfactants such as sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, and glycerin fatty acid ester Alkylamine salts, cationic surfactants and alkyl betaines, such as quaternary ammonium salts, amphoteric surfactants such as amine oxides. Among them, anionic surfactants typified by alkyldiphenyl ether disulphonic acid salts are particularly preferably used.

The coverage of the surfactant on the surface of the crosslinked polymer particles used in the present invention is 5% or more, preferably 10% or more. If the surface coverage of the crosslinked polymer particles with the surfactant is less than 5%, the improvement of the dispersibility in the polyester is hardly achieved. The average particle size of the cross-linked polymer particles coated with the surfactant used in the present invention is 0.01 to 3 μm, preferably 0.05 to 2 μm, and more preferably 0.1 to 1.
It is 5 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, when it exceeds 3 μm, the surface roughness becomes too large, which is not preferable. In the present invention, the ratio (Dw / Dn) of the weight average particle diameter (Dw) to the number average particle diameter (Dn) of the crosslinked polymer particles is usually 1.
It is 3 or less, preferably 1.2 or less, and more preferably 1.1 or less. If this value exceeds 1.3, the uniformity of the film surface may be impaired. The particles to be used may or may not be porous, but the former is preferred because it has a better affinity with polyester.

The glass transition temperature of the crosslinked polymer particles used in the present invention is usually 90 ° C. or higher, preferably 110 ° C. or higher. Particles having a glass transition temperature of less than 90 ° C may be deformed by a strong stress during stretching. One embodiment of the production of crosslinked polymer particles having a specific coverage in the present invention is as follows. That is, after dissolving a predetermined amount of a surfactant and a predetermined amount of a water-soluble polymerization initiator such as hydrogen peroxide or potassium persulfate in an aqueous medium, a predetermined amount of the compounds (A) and (B) is dissolved. Is added. Thereafter, the decomposition initiation temperature of the polymerization initiator or higher, preferably 30 to
The reaction is carried out at 90 ° C. for about 3 to 10 hours with stirring. In this case, since the particles are obtained as a uniformly dispersed water slurry, it is preferable to substitute the ethylene glycol slurry for blending with the polyester or take out the particles as dried particles. In any case, the method for producing the crosslinked polymer particles does not matter as long as the gist of the present invention is satisfied.

In the present invention, the content of the crosslinked polymer particles in the polyester is 0.01 to 3% by weight,
It is preferably 0.05 to 2% by weight. Compounding amount 0.0
If it is less than 1% by weight, the slipperiness and abrasion resistance of the film are insufficient, and conversely, if it exceeds 3% by weight, the surface roughness of the film becomes too large and the electromagnetic properties deteriorate, which is not preferable. The method of blending the crosslinked polymer particles used in the present invention with the polyester film-forming raw material is not particularly limited,
A known method can be adopted. For example, when the particles are obtained as an ethylene glycol slurry dispersion, the polycondensation reaction is carried out at any stage of the polyester production process, preferably after the esterification or transesterification reaction and before the polycondensation reaction is started. You should proceed.

Thus, the present invention uses certain cross-linked polymeric particles, the effect of which is particularly pronounced when such particles are combined with some of the following requirements. First, 80 mol% ethylene terephthalate unit
In the case of a film containing the above, the refractive index in the thickness direction of the film is set to 1.492 or more. At this time, the effect of improving the slipperiness and wear resistance becomes remarkable, and the adhesiveness with the magnetic layer also improves. The refractive index in the thickness direction of the film is preferably 1.494 to 1.505. The film having such physical properties is, for example, in the case of sequential biaxial stretching, the longitudinal stretching temperature is 85 to 115 ° C. which is higher than the normal stretching temperature by 5 to 30 ° C.
It can be obtained by setting the temperature to about ° C.

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 better and the magnetic tape
It is suitable as a film. Cutability here
Is to slit the magnetic tape with a shear cutter, etc.
If the cutting property is poor, the cut end is streaky.
Curling up, whiskers or powder from the cut
To do. When such a phenomenon occurs, white powder adheres to the tape.
The electromagnetic conversion characteristics and dropouts.
Wake up. Δn is preferably 0.020 or more, more preferably
It is preferably 0.025 or more, particularly preferably 0.035 or more.
Above. If Δn is too large, heat shrinkage
Because of inconvenience, the upper limit of Δn is 0.060.
It is preferable. Furthermore, the limit of polyester film
The viscosity is preferably 0.52 to 0.62, and 0.54 to
0.59 is more preferable. The lower the intrinsic viscosity,
Rum has good cutting properties, but intrinsic viscosity is less than 0.52
In the case of, the film breakage tends to occur during film formation.
There is a direction. On the other hand, when the intrinsic viscosity exceeds 0.62,
The effect of improving the cuttability of the film may be insufficient.

The second combination in which the effect of the present invention is 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 of the film is 900 kg / mm. ² or more, preferably 1000 kg / mm ² or more, further 1100 kg
/ Mm ² or more. Usually, when strongly stretched to have such a high strength, 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 decreases. There is a tendency. Such a high-strength film can be obtained, for example, by the following film forming method. That is, a substantially non-oriented unstretched sheet is stretched in the longitudinal direction 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, biaxial stretching is carried out sequentially in the longitudinal and transverse directions or simultaneous biaxial stretching, and at a temperature of 110 to 180 ° C, 1.05 to 1.05 in the longitudinal direction.
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 particles are blended in a film containing 80 mol% or more of polyethylene-2,6-naphthalate units. Among the polyester films, polyethylene-
A film containing 80 mol% or more of 2,6-naphthalate units has attracted attention because of its excellent mechanical strength and heat resistance, but it is often used under more severe conditions in terms of running speed and tension of the film. Therefore, improvement in wear resistance is particularly desired. In particular, the sum of the Young's modulus in the machine direction and the Young's modulus in the machine direction of the film containing the particles used in the present invention is 1300 kg / mm ² or more, and further 1400 kg.
/ Mm ² or more, particularly 1500 kg / mm ² or more, the effect of improving the wear resistance becomes remarkable. In the case of polyethylene-2,6-naphthalate, such a high-strength film can be obtained by the same method as that for polyethylene terephthalate except that the stretching temperature is increased. That is, a substantially non-oriented unstretched sheet is treated at 90 ° C to 180 ° C.
3.0 to 6.0 times in the vertical direction at 0 ° C, and then 3. in the horizontal direction.
It is a method of stretching 0 to 6.0 times and heat treating at 180 to 260 ° C. Of course, a method of sequentially biaxially stretching in the longitudinal and transverse directions or simultaneous biaxial stretching, re-stretching 1.05 to 4.0 times in the longitudinal direction at a temperature of 140 ° C. to 200 ° C., and then performing a heat treatment 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.

In the present invention, it is possible to further improve the running property, abrasion resistance, scratch resistance and the like of the film by using one or more other particles in combination within the 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 allowed to exist, and the polycondensation reaction is carried out in the presence or absence of the 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 that are added to the polyester from the outside. 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. Particles used in combination in the present invention, when the average particle size is larger than the average particle size of the crosslinked polymer particles of the present invention,
The amount is preferably equal to or less than that of the crosslinked polymer particles, and 0.005 to
0.5 times by weight is more preferable, and 0.01 to 0.3 times by weight is particularly preferable. On the other hand, when the average particle size is smaller than the average particle size of the crosslinked polymer particles of the present invention, the amount is preferably equal to or more than that of the crosslinked polymer particles, and more preferably 1 to 20 times the weight.

In recent years, improvement in scratch resistance has been demanded,
It is particularly preferable to select aluminum oxide as the particles to be used in combination. Especially the average particle size of the secondary aggregate is 0.5 μm
The following is preferable, a delta type or gamma type of 0.1 μm or less is more preferable, and a delta type of 0.1 μm or less is particularly preferably used. As a method for producing these particles, 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, aluminum hydroxide is used as a raw material and reacted with sulfuric acid to form aluminum sulfate. Then, a method of reacting with ammonium sulfate and baking it as ammonium alum can be mentioned. The primary particle size of aluminum oxide obtained by these methods is usually 5
Although it is in the range of ˜40 nm, it often forms aggregates exceeding 0.5 μm, so it is desirable to use it after appropriately crushing. In the present invention, two or more kinds of crosslinked polymer particles having different average particle sizes may be used, and in particular, for the purpose of improving winding characteristics and running property, large particle crosslinked polymer particles and small particle crosslinked polymer particles are used. Are preferably combined. Here, the large cross-linked polymer particles mean those having an average particle size of 0.5 to 2 μm, and the content thereof is 0.005 to
0.15 wt% is particularly preferable, on the other hand, small cross-linked polymer particles refer to those having an average particle size of 0.10 to 0.8 μm, and the content is 0.20 to 3.0 wt%. Particularly preferred.

Thus, by blending the specific crosslinked polymer particles and other particles such as aluminum oxide particles as required, an extremely excellent polyester film particularly suitable for a magnetic recording medium can be obtained. It will be possible.
The particles used in the present invention 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 may be subjected to treatments such as crushing, dispersing, classifying and filtering in advance, if necessary. The slurry concentration in the added ethylene glycol is usually 5 to 50% 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 unit consumption of ethylene glycol increases. Further, when a slurry having a particle concentration of more than 50% by weight is added, the dispersibility of particles may be deteriorated. As the polycondensation reaction catalyst for polyester synthesis, a commonly used catalyst such as Sb, Ti, Ge, Sn and Si compounds is used.

The center line average roughness (Ra) of the film surface of the present invention is preferably 0.005 to 0.1 μm,
007-0.08 μm is more preferable, and 0.01-
0.03 μm is particularly preferable. Further, the ratio of the maximum protrusion height (Rt) to the center line average roughness (Ra), Rt / Ra, of the film of the present invention is preferably 15 or less, 12
The following is more preferable, and 5 or more and 10 or less is particularly preferable. If the Rt / Ra value exceeds 15, the running property or wear resistance tends to be poor. The film of the present invention is a single layer or 2 if it satisfies the constitutional requirements of the present invention.
It may be a laminated film having more than one layer. The film of the present invention is not only prized as a base film for video tapes, but also particularly effective when used as a base film for audios and floppy disks. Of course, it can be used for a dielectric of a capacitor, for packaging, for plate making, and for other purposes, if necessary.

[0021]

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 Shimadzu's centrifugal sedimentation type particle size distribution measuring device (SA-CP
Equivalent spherical distribution measured by type 3) 5
The particle size d _{50 of} 0% was taken as the average particle size. This value is the weight average particle size (Dw), but at the same time, the number average particle size (Dn).
Was also obtained and the ratio (Dw / Dn) of both was used as an index of the particle size distribution.

(2) Coverage (coverage of surfactant on the surface of cross-linked polymer particles) X-ray fluorescence analysis method (Rigaku Denki System 3370)
-Type fluorescent X-ray analyzer) to determine the content of S element in the surfactant on the particle surface to determine the amount of surfactant on the particle surface, and the specific surface area of particles measured by the BET method and the molecular occupation of the surfactant. The coverage was calculated from the area.

[Equation 3]

(3) Intrinsic viscosity of film 1 g of polymer was added to phenol / tetrachloroethane = 50
Dissolve in 100 ml of a mixed solvent of 50/50 (weight ratio) and
It was measured at 0 ° C. (4) Refractive index of film Using an Abbe refractometer manufactured by Atago Optical Co., Ltd., the refractive index (nα) in the thickness direction, the refractive index (n _TD ) in the width direction and the refractive index (n _MD ) in the longitudinal direction of the film were measured. It was measured. The sodium D line was used to measure the refractive index. (5) Young's modulus (tensile modulus) 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 ), stress difference due to the original average cross-sectional area between two points on the straight line, and strain difference between the same two points)

(6) Average Roughness of Film Surface and Uniformity of Roughness According to the method described in Japanese Industrial Standard JIS B0601, Kosaka Laboratory Ltd. surface roughness measuring machine (SE-
3F) was used to determine the centerline average roughness (Ra) and maximum height (Rt). The radius of the stylus used is 2.0μ
m, load is 30 mg, cut-off value is 0.08 m
m. The smaller Rt / Ra, the more uniform the surface. (7) Runnability It was evaluated by the slip property of the film. The slipperiness is determined by contacting the film around a fixed hard chrome-plated metal roll (diameter 6 mm) at an angle (θ) of 135 °, applying a load of 53 g) to one end, and running it at a speed of 1 m / min. The resistance force (T ₁ , g) was measured, and the friction coefficient (μd) during running was determined by the following formula. μd = 0.424 ・
ln (T _1/53)

(8) Number of Coarse Protrusions Aluminum was vapor-deposited on the surface of the film, and the number was measured by the two-beam method using a Nikon Optiphoto interference microscope. The number of projections (projection height of 0.81 μm or more) showing interference fringes of third order or more at a measurement wavelength of 0.54 μm was measured over an area of 100 cm ² , and the number of coarse projections was obtained. (9) 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

(10) Film winding characteristics The roll misalignment, wrinkling, winding appearance, etc. during the winding operation of the polyester film were evaluated comprehensively. (11) Magnetic Tape Properties 200 parts of magnetic fine powder, 30 parts of polyurethane resin, 10 parts of nitrocellulose, 10 parts of vinyl chloride-cellulose acetate copolymer, 5 parts of lecithin, 100 parts of cyclohexanone,
100 parts of methyl isobutyl ketone and 300 parts of methyl ethyl ketone were mixed and dispersed in a ball mill for 48 hours,
Add 5 parts of polyisocyanate compound to make a magnetic paint,
This was applied to a polyester film, 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 subjected to a roll temperature of 85 ° C., a linear pressure of 250 kg / cm, and a running speed of 80 using a five-stage super calender composed of a mirror-finished metal roll and a polyester-based composite resin roll.
The amount of white powder adhering to the resin roll was visually evaluated by repeatedly running 7 times over 5000 m under the condition of m / min, and evaluated according to the ranks shown below. ◯: Almost no white powder is seen on the resin roll Δ: Very slight white powder is seen ×: Clearly white powder is seen Next, the calendered film is 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.

(A) 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 the standard tape 〇… same as the standard tape △… inferior to the standard tape ×… obviously inferior to the standard tape and unusable for practical use (B) Maximum dropout number 4.4 MHz signal recorded The produced video tape was reproduced, and the number of dropouts was measured with 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.

(12) 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 crosslinked polymer particles] In 1500 parts of demineralized water, 3.2 parts of a water-soluble polymerization initiator potassium persulfate and anionic surfactant sodium lauryl sulfate (trade name: Emal 0
1 part (manufactured by Kao Corporation) was added and dissolved uniformly, and then a mixed solution of 65 parts of ethylene glycol dimethacrylate, 10 parts of methyl methacrylate, 5 parts of 1.4 butanediol diacrylate and 20 parts of divinylbenzene was added. Then, at 70 ° C. with stirring under a nitrogen gas atmosphere.
The polymerization reaction was carried out for 12 hours. The reaction rate was 98%, the average particle size of the obtained particles was 0.50 μm, and the particle size distribution value (Dw / D
n) was 1.05, and the coverage of the surfactant was 50%. In addition, when the obtained particles were observed with an electron microscope, they were almost spherical. 2000 parts of ethylene glycol was added to the water slurry of the obtained particles, 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 were placed in a reactor, heated and heated, and methanol was distilled off 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, after adding 8 parts of the above slurry, 0.03 part of phosphoric acid and 0.04 part of antimony trioxide were further added, and polycondensation reaction was carried out for 4 hours to obtain polyethylene terephthalate having an intrinsic viscosity of 0.61. When the inside was observed with a microscope, it was confirmed that the particles were uniformly dispersed.

[Production of Polyester Film] After drying the obtained polyester, it is melt-extruded at 290 ° C. to obtain an amorphous sheet, which is 3.5 times at 93 ° C. in the sheet flow direction (longitudinal direction) and 110 in the transverse direction. Stretched 3.5 times at ℃, 220
A heat treatment was carried out at ℃ for 3 seconds to obtain a film having a thickness of 15 μm. The Young's modulus of the obtained film is 430 kg in the longitudinal direction.
/ Mm ² , and the horizontal 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 A film was obtained in the same manner as in Example 1 except that the crosslinked polymer particles used in Example 1 were used and the refractive index in the thickness direction of the film was set to 1.490, and the characteristics thereof were evaluated. did. Example 3 A film was obtained in the same manner as in Example 1 except that the crosslinked polymer particles used in Example 1 were used and the birefringence of the film was set to 0.006, and the characteristics thereof were evaluated.

Comparative Example 1 A film was obtained in the same manner as in Example 1 except that the coverage of the crosslinked polymer particles used in Example 1 was 2%, and its characteristics were evaluated. Comparative Example 2 Kaolin particles having an average particle size of 0.45 μm and a particle size distribution value (Dw / Dn) = 1.35 in Example 1 were used, and the content was as shown in Table 2 except that the content was as shown in Table 2. Then, a polyethylene terephthalate film was obtained, and its characteristics were evaluated.

Example 4 Along with the cross-linked polymer particles used in Example 1, the primary particle size was 0.
A film was obtained in the same manner as in Example 1 except that delta-type aluminum oxide having an average secondary particle diameter of 02 μm and 0.08 μm was blended as shown in Table 2, and its properties were evaluated. The intrinsic viscosity of the film was 0.59. Example 5 After using the crosslinked polymer particles used in Example 1 and stretching in the machine 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 6 The transesterification reaction was carried out in the same manner as in Example 1 except that dimethyl-2,6-dimethylnaphthalate was used instead of dimethyl terephthalate in the production of the polyester of Example 1. Then, 8 parts of the ethylene glycol slurry containing the crosslinked polymer particles used in Example 1 was added,
Further, 0.03 part of phosphoric acid and 0.04 part of antimony trioxide were added and polycondensation reaction was carried out by an ordinary method to obtain an intrinsic viscosity of 0.5.
Polyethylene-2,6-naphthalate of 9 was obtained. The obtained polymer is subjected to solid-state polymerization at 0.3 mmHg and 235 ° C. for 7 hours to obtain polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.68, extruded into a sheet at 295 ° C. from an extruder and cooled by electrostatic application. An amorphous sheet having a thickness of 100 μm was obtained by using the 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.

Comparative Example 2 Using the particles used in Comparative Example 1, a film was obtained in the same manner as in Example 6 and its characteristics were evaluated. Example 7 Along with the crosslinked polymer particles used in Example 5, a primary particle size of 0.
Delta-type aluminum oxide having an average secondary particle size of 02 μm and an average secondary particle size of 0.08 μm was blended as shown in Table 2, and the Young's modulus in the longitudinal direction was 1010 kg / mm ² in the same manner as in Example 6. A polyethylene-2,6-naphthalate film was obtained and its characteristics were evaluated.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

EFFECT OF THE INVENTION The film of the present invention has a uniform and fine surface structure, is excellent in abrasion resistance and running property, can be applied to various uses, and has a high industrial value.

Claims (1)

[Claims] 1. A crosslinked polymer particle having an average particle size of 0.01 to 3 μm and a coverage of a surfactant defined by the following formula of 5% or more is contained in an amount of 0.01 to 3% by weight. Axial oriented polyester film. [Equation 1] [In the above formula, the area occupied by the surfactant is the area occupied by the surfactant (m ² / g) on the surface of the crosslinked polymer particles, and the specific surface area is BET.
Represents the specific surface area (m ² / g) of the crosslinked polymer particles measured by the method]