JPS61177227A - Orientated polyester film - Google Patents

Abstract

PURPOSE:To improve the electromagnetic conversion characteristics and running characteristics in oriented polyester film employed as substrate of video tapes such as metallization type tapes, vacuum evaporation type tapes and the like by a method wherein specified particles of silica or titanium oxide and specified particles of calcium carbonate are employed in polyester. CONSTITUTION:Polyester, in which 0.01-0.5wt% of particles of either silica or titanium oxide with a mean particle size of 0.01-0.1mum and 0.005-0.3wt% of particles of calcium carbonate with a mean particle size of 0.01-0.1mum are contained, is orientated. Crystalline polyester such as polyethylene terephthalate, polyalkylene naphthalate or the like is employed as the polyester. Especially polyethylene terephthalate is preferable. The resultant film has excellent electromagnetic conversion characteristics for video tapes, the surface smoothness of which is requested, such as metallization type tapes, vacuum evaporation type tapes and the like and at the same time has favorable slipperiness, wear resistance and a durable running property. In addition, extremely few coarse particles, which cause to occur drop outs, are produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an oriented polyester film that is excellent in smoothness, running characteristics, and abrasion resistance, and particularly has excellent electromagnetic conversion characteristics when used as a magnetic recording substrate.

In general, polyesters such as polyethylene terephthalate are used for textiles, molded products, magnetic tapes, floppy disks, photographs, condensers, and packaging because of their excellent physical and chemical properties. It is widely used in a variety of applications, including for films such as X-ray film, microfilm, etc. When these films are used, their slipperiness and abrasion resistance are major factors that determine the workability of the film manufacturing process and processing process for each application, as well as the quality of the product. ing. In particular, when a magnetic layer is applied to the surface of a polyester film and used as a magnetic tape, the friction and abrasion between the coating roll and the film surface during application of the magnetic layer is extremely severe, causing wrinkles and scratches on the film surface. It's easy to do. Furthermore, even after the film coated with the magnetic layer is slit and processed into audio, video, or computer tapes, there are many guide parts, playback heads, etc. when pulling out from a reel or cassette, winding it up, or performing other operations. Significant friction ν and wear occur between the two, causing scratches and distortion, as well as complete precipitation of white powdery substances due to scratches on the surface of the polyester film, which is often a major cause of missing magnetic recording signals, that is, dropouts. . In addition, when used repeatedly as a magnetic tape, the coefficient of friction between it and the metal guide roller increases with the number of times it is used, and in extreme cases, the guide roller may wind up the tape, or the tape and playback head may become loose. A so-called squeal may occur between the guide rollers, deteriorating the running characteristics. Among these, metal-coated and vapor-deposited magnetic tapes that require a high S/N ratio, such as video tapes that require surface smoothness, have very thin magnetic layers, so the base film used is The surface morphology of the it magnetic layer becomes the surface morphology of the it magnetic layer. Therefore, if the surface roughness of the base film is rough, the electromagnetic conversion characteristics of the videotape will deteriorate significantly after the metal magnetic material has been completely coated or vapor-deposited. A base film with a completely smooth mirror surface free of insoluble particles is preferable, or the magnetic layer formed on such a base film maintains its mirror surface as it is, so it has good processability such as slipperiness and abrasion resistance. It is extremely poor, and the running durability is also extremely poor.

In general, to improve the slipperiness, abrasion resistance, and running durability of films, a method is adopted in which the surface of the film is made uneven to reduce the contact area with guide rolls, etc.3. Methods for forming surface irregularities include a method in which insoluble particles are precipitated from a contact residue of a polymer used as a film raw material, a method in which inert inorganic particles are added, and the like. Generally speaking, the larger the size of the particles in these raw polymers, the greater the effect of improving slipperiness.However, magnetic tapes, especially metal-coated and vapor-deposited types, require surface smoothness. For precision applications such as video tapes, the large particles themselves can cause defects such as dropouts, and the electromagnetic conversion characteristics can also be significantly deteriorated, so the unevenness on the film surface must be as fine as possible. Currently, there are demands to satisfy contradictory characteristics at the same time.

(Problems to be Solved by the Invention) The object of the present invention is particularly when an oriented polyester film is used as a base material for a magnetic tape, particularly a videotape base material that meets all requirements for surface smoothness such as a metal coated type or a vapor deposited type. The object of the present invention is to provide an oriented polyester film having good electromagnetic conversion properties and good running properties.

(Means for solving the problem) The present invention provides polyester with an average particle size of 0.01 to 0.
．． This is an oriented polyester film containing 0.01 to 0.5 M of silica particles of 1 μm in total and 0.005 to 0.3 M of calcium carbonate particles Th with an average particle diameter of 0.01 to 0.1 μm.

The oriented polyester film of the present invention has an ultra-smooth surface, and is also improved in processability such as slip resistance and abrasion resistance, and durability when silica particles or calcium carbonate particles are used alone or when other particles are added. In particular, when used for video tapes that require surface smoothness, such as metal-coated type and vapor-deposited type, there are fewer defects such as dropouts, and the electromagnetic conversion characteristics are extremely excellent. We have found that this is suitable and have arrived at the present invention.

The polyester used in the method of the present invention is a crystalline polyester of polyethylene terephthalate, polyalkylene naphthalate, etc., and although not particularly limited, polyethylene terephthalate is particularly suitable, especially 80 moles of repeating units thereof. The upper part consists of ethylene terephthalate, and other copolymerized components include isophthalic acid, P-β-oxyethoxybenzoic acid, and 2.6
-7thalenedicarboxylic acid, 4,4'-dicarboxyldiphenyl, 4,4'-dicarboxylbenzophenone, bis(4-carboxylphenyl)ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid , dicarboxylic acid components such as cyclohexane-1,4-dicarboxylic acid, propylene glycol, butanediol,
Glycol components such as neopentyl glycol, diethylene glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polyethylene glycol, polytetramethylene glycol, oxycarboxylic acid components such as P-oxybenzoic acid, etc. are optionally used. I can do something. In addition, a small amount of a compound containing an amide bond, urethane bond, ether bond, carbonate bond, etc. may be included as a copolymerization component.

The method for producing the polyester includes a so-called direct polymerization method in which aromatic dicarboxylic acid and glycol are directly reacted;
Any production method can be applied, such as the so-called transesterification method in which dimethyl ester of aromatic dicarboxylic acid and glycol are transesterified. The film may be either a uniaxially oriented film or a biaxially oriented film, but a biaxially oriented film is particularly preferred.

In the present invention, inert inorganic fine particles lj to be added
The average particle size of silica 2 and titanium oxide, which are the first components of
O, O8 to 0.09 μm is more preferable. Particularly preferred is 0.0+-0.08 μm. If it is less than 0.0.1# shoulder, it is not preferable because slipperiness, abrasion resistance ν, and running durability deteriorate significantly. On the other hand, 0. If it exceeds I#*, the electromagnetic conversion characteristics will be insufficient for magnetic tapes, especially video tapes that require surface smoothness such as metal-coated type and vapor-deposited type, and are not preferred. Also, the amount added is 0. It is necessary to set it as O1-0.5 weight%, and 0.05-0.8 weight% is more preferable.

If it is less than 0.01% by weight, slipperiness, abrasion resistance, and running durability are significantly deteriorated, which is not preferable. On the other hand, if it exceeds 0.5% by weight, the electromagnetic conversion characteristics will be insufficient for magnetic tapes, especially video tapes that require surface smoothness such as metal coating type 2 and vapor deposition type, which is not preferred.

The average particle diameter of calcium carbonate, which is the second component of the inert inorganic fine particles to be added, must be 0.01 to Q, I#m, and preferably O, Oa to 0.09 μm. Particularly preferably, it is 0.0 to 0.08 μm. If the thickness is less than 0.01 μm, slipperiness, abrasion resistance, and running durability are significantly deteriorated, which is not preferable. On the other hand, if it exceeds 0.1 .mu.m, the electromagnetic conversion properties will be insufficient for magnetic tapes, especially video tapes such as metal-coated type and vapor-deposited type that require full surface smoothness, and are not preferred.

In addition, the amount added is o, o o with respect to the polyester.
Must be 5-0.3% by weight, 0.05-0.2
% by weight is more preferred. If it is less than 0.005% by weight, slipperiness, abrasion resistance, and running durability are significantly deteriorated, which is not preferable. On the other hand, if it exceeds 0.3% by weight, the electromagnetic conversion properties will be insufficient for use in magnetic tapes, especially video tapes that require surface smoothness such as metal coated type and vapor deposited type, which is undesirable.

There are no limitations on the manufacturing method or other aspects of these particle components as long as they satisfy the conditions specified above. Further, the relationship between the average particle diameter and the amount added of each particle component can be arbitrarily selected as long as it satisfies the conditions specified above. As calcium carbonate, both natural products and synthetic products can be used. For example, any of heavy calcium carbonate, light calcium carbonate, and colloidal calcium carbonate may be used.

These particles may be used without surface treatment and are not particularly limited.

Further, the crystal shape of each particle is not particularly limited, but it is preferable to use particles with a volume shape coefficient in the range of 0.08 to /6.

[However, the volumetric shape factor f is expressed by the following equation.

f=v/D3 In the formula, V indicates the particle volume (μm), and D indicates the maximum diameter (μm) of the particle on the projection plane P. ] The volume shape factor represents the degree of agglomeration of particles, and ff
The closer it gets to /6, the more it becomes lumpy or spherical.

Is the average particle size of calcium carbonate particles silica particles? It does not matter whether the particle size is larger or smaller than the average particle size of the particles and the titanium oxide particles, but it is more preferable that the particle size is larger than the average particle size of the particles and the titanium oxide particles.

The average particle diameter referred to herein refers to the diameter multiplied by 3 at the cumulative 50% point of the uniform spherical diameter particle size distribution calculated based on Stokes' formula.

The method of adding fine particles to polyester according to the second aspect of the present invention is that they can be added at any stage of the polyester production process, but it is particularly clever to add them before the initial condensation is completed. Fine particles can be added to the polyester manufacturing process either in the form of a slurry or powder, but it is preferable to disperse them in a slurry to prevent particles from scattering and improve supply accuracy and uniformity. It is preferable to add it as a slurry of ethylene glycol (EG) at <,%. When dispersing in slurry form, it is necessary to perform uniform dispersion so as to reproduce the original primary particles of each particle as much as possible. In addition, in order to obtain particles with a predetermined average particle size,
It is also possible to adopt pulverization treatment or classification operation of commercially available fine particles.

When adding the particles as a slurry, 5 in the slurry
It is particularly preferable to add particles with a particle diameter of .mu.m or larger to 0.5% by weight or less based on the total particles in order to reduce the amount of coarse particles.

In addition, when the particles are added as a slurry to the polyester manufacturing process, the silica or titanium oxide slurry and the calcium carbonate slurry may be added at the same time or may be added separately. If they are added at the same time, they may be added from separate supply ports, or they may be added after uniformly mixing both slurries before adding them to the polyester manufacturing process.

Also, individual particles within the range of non-agglomeration? Polyester containing a high concentration may be prepared separately in advance and then blended to a predetermined particle concentration.

Even if it contains fine particles precipitated during the polyester manufacturing process, so-called internal particles, as long as the average particle size and needle content are such that it does not increase the number of coarse particles and does not have a negative effect on surface smoothness. I don't mind. In addition, when the purpose of the film is such that only one side of the film comes into contact with a metal roll, only the contacting side can contain the inert inorganic particles of the present invention, and the other side can contain inert inorganic particles depending on the purpose. Alternatively, it may be a separate layer that does not contain it.

(Example) Next, Example 2 of the present invention and all comparative examples will be shown.Unless otherwise specified, parts in the examples mean all parts by weight.

In addition, the measurement method used is shown below.

(1) Processability of the film When the film is rubbed on a purple metal guide roll and run at high speed for a long time, the magnitude of the tape tension after the guide roll is rubbed against a constant supply tension. The amount of white powder generated on the surface of the guide roll was evaluated on a five-point scale, and the following rankings were used:

(a) Smoothness Grade 1...Tension is applied (many scratches) Grade 2...Tension is slightly weak (many scratches and scratches) Grade 3...
Medium tension (with some scratches) Grade 4: Tension is slightly low (no scratches) Grade 5: Low tension (no scratches at all) (B) Abrasion resistance: Grade 1: white powder 2nd grade with very high white powder generation... 8th grade with a lot of white powder generation... Some white powder generation 4th grade... Almost no white powder generation 5th grade... No white powder generation at all Under an atmosphere of 65 cm, polyester The entire surface of the rough side of the film was coated with a commercially available household VTR guide pin (maximum protrusion height measured with a stylus surface roughness meter was 0.15μ chips, center line average roughness was o, oosμN) with a surface roughness of 8. /4π (unit: radian), constant load of 50 grams, tension applied, Kranfuke angular velocity: 8. The increase in the dynamic friction coefficient and static friction coefficient from the initial dynamic friction coefficient and initial static friction coefficient, respectively, when the film is rotated at Orpm and reciprocated 100 times (
Δμkd i- and Δμks ) are evaluated in five stages and expressed in the following ranking.

1st class: Increase in friction coefficient 0.20 or more 2nd class: 0.
15-0.20 8th grade...0.10-0.15 4th grade...0.05-0.10 5th grade...less than 0.05 (3) Average particle size Centrifugal sedimentation manufactured by Takasu Seisakusho The value at the cumulative 50% point of P in the uniform sphere diameter distribution obtained by a particle size distribution analyzer (CP-50 type) is used.

(4) Film surface smoothness (TAB) The film surface was measured using a stylus-type 8-dimensional surface roughness meter manufactured by Koita Institute Co., Ltd. (SE-8AK).
)k, under the conditions of needle radius 2 μm 1 load 70 mm,
The film is measured over a reference length of 1 m with a cutoff value of 0.251 in the longitudinal direction, and when 2 /J m >-, data in the height direction is imported into an external storage device with a quantization width of 0.00812 μm. Such measurements are carried out 150 times in succession at 2 μm intervals in the transverse force direction of the film, that is, over a width of 0.8 mm in the transverse direction of the film.

At this time, the data in the height direction h(i, j) (i=
1-500. j = 1 to 150), the value obtained by calculating the following formula and expressed in μm is TA
R [Three-Dimensional Average Roughness].

・・・・・・・・・ (1) 6) Number of coarse particles in the film Place a small amount of the film between two cover glasses.
After melt-pressing at 0°C and quenching, it was observed using a phase contrast microscope and processed using an image analysis processing device Luzex 500 (manufactured by Nippon Regulator) to determine the number of particles with a maximum length of 5 μm or more in the particle image. (The number of particles per measurement area of 4.8 m2) is counted and ranked according to the number of particles as follows.

1st grade...51 pieces or more/48 fins 2 2nd grade...21-50 pieces/4.8 fins 2 3rd grade...11-20 pieces/4.8 fi"4th grade...4
~lO pieces/4.8■2 Grade 5...0 to 8 pieces/4.8■2 (6) Electromagnetic conversion characteristics (S/N ratio) S/N ratio Fi50 when the above film is made into a full magnetic tape
% white level signal is measured at the optimum recording current for each tape, and the signal-to-noise ratio (S
Using a video noise measuring device, the S/N ratio of each tape relative to a commercially available standard tape was evaluated on a five-level scale and expressed in the following rankings.

Grade 1...S/N ratio Grade 2...S/N ratio Slightly grade 8...S/N ratio Grade 4...S
/N ratio: Slightly high Grade 5...S/N ratio: Large example l.

A continuous esterification reactor consisting of a two-stage complete mixing tank equipped with an agitator, a dephlegmator, a raw material inlet and a product outlet is used, and the esterification reaction product in the first esterification reactor is The molar ratio of EG to terephthalic acid (TPA) was adjusted to 1.7 in the existing system, and antimony trioxide was added per unit of TPA using an antimony atom.
EG slurry of TPA containing ppm was continuously fed.

At the same time, the KG solution of magnesium acetate tetrahydrate and the EG bath solution of sodium acetate pass through the reactor through a supply port different from the TPA EG slurry supply port. and Na atoms were continuously supplied at concentrations of 10 ppm and 10 ppm, and the average residence time was 4.5 hours at normal pressure.
The reaction was carried out at a temperature of 255°C.

All of this reaction product was continuously taken out of the yarn and supplied to the second esterification reactor. 0.5 parts by weight of E, G, . . . )limethyl phosphate in EG solution 1 p atom based on the polyester unit in the reaction product passing through the second esterification reactor is 64° ppm2? and EG slurry of silica with an average particle size of 0.04 μm and an average particle size of 0.
．． Calcilla carbonate spring EG slurry of 0.8 μm gold, silica, and calcium carbonate of 0.25% by weight and 0.15% by weight, respectively, were continuously supplied from separate Ω supply ports, and the average residence time was 5.5% at normal pressure. The reaction was carried out for 0 hours at a temperature of 260°C.

The esterification reaction product is continuously supplied to a two-stage continuous polycondensation reactor equipped with a stirrer, a partial condenser, a raw material inlet, and a product outlet for polycondensation. Polyester was obtained.

The entire polymer was melt extruded at 290°C, stretched 3.5 times in the longitudinal direction at 90°C, and 3.5 times in the transverse direction at 130°C.
Table 1 shows the film properties of the 15 μm film obtained by heat treatment at 20°C. The obtained film t''i is particularly suitable for use in magnetic video tapes that require surface smoothness such as metal coated type 3 and vapor deposition type, and has excellent electromagnetic conversion characteristics, surface smoothness, slipperiness, abrasion resistance, number of coarse particles, and durability. It is good regardless of the running properties.

Comparative Examples 19 and 2 Same as Example 1 except that silica with an average particle size of 0.04 μm was used alone at 0.15% by weight of silica with an average particle size of 0.04 μm and calcium carbonate with an average particle size of 08 μm. Table 1 shows the physical properties of the film obtained by the method. The films obtained in these comparative examples had poor running durability and slipperiness, and neither of them were sufficient for use in video tapes that require surface smoothness, especially metal-coated type and vapor-deposited type. The quality is incredible.

Comparative Example 8 Table 1 shows the film properties of a film obtained in the same manner as in Example 1 except that the amount of calcium carbonate added was changed to 0.40% by weight. The film obtained in this comparative example was inferior in terms of coarse particles, and did not have sufficient quality for video tapes requiring surface smoothness such as metal coating type and vapor deposition type.

Comparative Example 4 Amount of silica added! The film properties of the film obtained in the same manner as in Example 1 except that k was changed to 1.20% by weight are shown in Table 1. The film obtained in this comparative example had poor electromagnetic characteristics, surface smoothness, and coarse particles. It does not have sufficient quality for video tapes that require surface smoothness, such as metal coating type v and vapor deposition type.

Example 2 A film obtained in the same manner as in Example 1 except that the average particle diameters of silica were changed to e o and os μm, and the amounts of silica and calcium carbonate added were changed to 0.20% by weight and 0.20% by weight, respectively. The physical properties of the film are shown in Table 1. The film obtained in this example has excellent electromagnetic characteristics, surface smoothness, slipperiness, abrasion resistance, and number of coarse particles, especially for use in video tapes that require surface smoothness, such as metal coating type υ and vapor deposition type. and running resistance, both of which are good.

Comparative Example 5 Table 1 shows the physical properties of a film obtained in the same manner as in Example 2, except that the average particle size of silica was changed to 35 μm around the side. The film obtained in this comparative example is inferior in terms of electromagnetic conversion characteristics, surface smoothness, and number of coarse particles, and is insufficient for video tape applications that require surface smoothness, especially metal-coated and vapor-deposited types. And yes & no quality.

・Example 3・ Added amounts of silica and calcium carbonate are both 0.10
Table 1 shows the physical properties of the film obtained in the same manner as in Example 1 except that the weight percentage was changed.

-21= The film obtained in this example has good electromagnetic characteristics, surface smoothness, slipperiness, abrasion resistance, coarse particle number ν, and running durability.

Example 4 Table 1 shows the physical properties of a film obtained in the same manner as in Example I, except that a layer of titanium oxide't O having an average particle diameter of 3.08 μm was used in an amount of 20% more by weight instead of the crimp force.

The film obtained in this example has good electromagnetic characteristics, surface smoothness, slipperiness, abrasion resistance, coarse particle number ν, and running durability.

(Effect of explanation) As described above, the film obtained by the present invention has excellent electromagnetic conversion characteristics especially for video tapes that require surface smoothness such as metal coated type and vapor deposited type, and also has slipperiness and It also has good abrasion resistance and running durability, and is characterized by extremely low generation of coarse particles that cause dropout defects.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic diagram of a tape tester for measuring the repeated running performance of a rough surface of a film. Each part will be briefly explained below. 1: Crank 2.4.6.8: Free roll 8.7: Tension detection device 9: Load 5: Commercially available VTR guide bin

Claims (2)

[Claims] (1) Average particle size in polyester is 0.01 to 0.1
0.01 to 0.5% by weight of at least one particle selected from silica and titanium oxide, and 0.0% by weight of calcium carbonate particles with an average particle size of 0.01 to 0.1 μm.
An oriented polyester film containing 0.05 to 0.3% by weight. (2) In the oriented polyester film described in claim 1, the oriented polyester film has electromagnetic conversion characteristics of grade 4 or higher.