JPS63128030A - Oriented polyester film - Google Patents

Abstract

PURPOSE:To provide the titled film outstanding in lubricity and wear resistance, insignificant in coarse asperities, thus suitable as a base for magnetic recording materials, containing specified proportions of inert particles with each specific average size, size distribution and shape. CONSTITUTION:Such inert particles that the average size fall between 0.05 and 5mum, size variation <=25% and area ratio to the circumscribed circle defined by formula [(projected sectional area of the particle/circumscribed circle area for the particle)X100]>=60% is incorporated in a polyester followed by its formation according to the conventional processes, thus obtaining the objective film containing 0.05-0.5wt% of said inert particles. It is recommended that said particles be of calcium carbonate, being incorporated before the completion of the initial condensation in the form of an ethylene glycol slurry.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to oriented polyester films.

More specifically, the present invention relates to an oriented polyester film that has excellent slip resistance and abrasion resistance, and has a small number of coarse projections, especially when used as a substrate for magnetic recording materials.

(Prior Art) Polyesters such as polyethylene terephthalate are generally used for textiles, molded products, and other applications due to their excellent physical and chemical properties.

For magnetic tapes, floppy disks, and photographs.

:l For packaging - X-ray film.

It is also widely used in a variety of applications, including for films such as microfilm. When used for these films, the slipperiness and abrasion are custom-made depending on the workability of the film manufacturing process and the processing process for each application.
Furthermore, it is a major factor that determines the quality of the product. 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, and wrinkles and scratches are likely to occur on the film surface. Furthermore, even after slitting the film coated with the magnetic layer and processing it into audio, video, or computer tapes, there are many guide parts, playback heads, etc. when pulling out from a leaf or cassette, winding it up, or other operations. Significant friction and abrasion occurs between the polyester film and the polyester film, causing scratches and distortion, as well as the precipitation of white powdery substances due to scratches on the surface of the polyester film, which can be a major cause of missing magnetic recording signals, that is, dropouts. many. Further, coarse protrusions caused by coarse particles contained in the additive particles often cause defects such as dropouts.

Conventionally, to improve the slipperiness and abrasion resistance of films, a method has been adopted in which the surface of the film is made uneven to reduce the contact area with guide rolls, etc.
As a method for forming this surface irregularity, a method is used in which insoluble particles are precipitated from a polymer residue used as a film raw material, a method in which inert inorganic particles or organic particles are added, etc. The particles in these raw polymers.

Generally, the larger the particle size, the greater the effect of improving slipperiness, but in precision applications such as magnetic tape, the large particle size itself can cause defects such as dropouts. Furthermore, since special orders for electromagnetic conversion are significantly deteriorated, it is necessary to precisely adjust the shape, density, height, etc. of the irregularities on the film surface.

Conventionally, the particle size distribution of particles has been considered only from the viewpoint of the average particle diameter, and the particle size distribution of each particle has not been controlled, which has the disadvantage that it is difficult to obtain a film surface shape as designed. Furthermore, regarding the shape of a single particle, considering the necessity of precisely adjusting the film surface shape, evaluation using the conventionally used volumetric shape coefficient alone is insufficient.

(Problems to be Solved by the Invention) The present invention eliminates the drawbacks of the prior art, particularly when an oriented polyester film is used as a base material for a magnetic tape, and has excellent V slip properties and abrasion resistance. It is an object of the present invention to provide an oriented polyester film having a small number of coarse protrusions.

(Means for Solving the Problems) The present invention has an average particle diameter of 0.05 μm or more and less than 5.0 μm, a variation degree of particle diameter of 25% or less, and an area with respect to a circumscribed circle represented by the following formula. Inert particles with a ratio of 60% or more t-o, o o sum s or more 0.
It is an oriented polyester film containing 5 fold fIk% or less.

The polyester used in the present invention is a crystalline polyester with polyethylene terephthalate, polyalkylene naphthalate, etc., and although it is not particularly limited, polyethylene terephthalate is particularly suitable, and in particular, 80 mol% or more of its repeating units are ethylene terephthalate. The other copolymer components include iso7
1%/acid.

p-β-oxyethoxybenzoic acid, 2,6-naphthalene dicarboxylic acid, 4,4'-dicarboxyl diphenyl, 4,4'-dicarboxyl benzophenone.

Bis(4-carboxylphenyl)ethane, adipic acid, sepacic acid, 5-sodium sulfoiphthalic acid,
V dicarboxylic acid component such as chlorohexane-1,4-dicarboxylic acid, propylene glycol.

Butanedio-/I/, neopentyl glyco-/L/, diethylene glycol, V-chlorohexane dimetatool.

Ethylene oxide adduct of bisphenol A.

polyethylene glycol, polypropylene glycol,
Glycol components such as polytetramethylene glycol, p
- Oxycarboxylic acid components such as oxybenzoic acid and the like can be arbitrarily selected and used.

In addition, compounds containing +m amide bonds, urethane bonds, ether bonds, carbonate bonds, etc. may also be included as copolymerization components.

The method for producing the polyester includes the so-called direct shaking 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.

The average particle diameter in the present invention is the one obtained by observation with a scanning electron microscope, but for the purpose of the present invention, the average particle diameter is 0.
．． 05 μm or more and less than 5.0 μm is preferable, but 0.1 μm
A range of m to 2.5 μm is particularly preferred. If the average particle diameter is less than 0.05 μm, the effect of improving slipperiness and abrasion resistance will be insufficient, which is not preferable. On the other hand, if it is 5.0 μm or more, it is not preferable because it may cause coarse protrusions on the film surface.

Further, the degree of dispersion of the average particle diameter is preferably 25 inches or less, particularly preferably 20 inches or less, considering the necessity of precisely adjusting the film surface profile.

In other words, if the particle size distribution is very close to monochromatic, the height and shape of the protrusions formed on the film surface are close to uniform, which corresponds to the intention of the present invention.

Regarding the shape of the particles, it is preferable that the shape of a single particle or a composite of particles formed by aggregation of primary particles is extremely similar to a true sphere.

That is, if the added particles are spherical, it is thought that the shapes of the protrusions formed on the film surface will be extremely similar.

In order to accurately define the particle shape based on this background, it is effective to combine observation using an F-type electron microscope and an image analysis device. The ratio of the area of the circle circumscribing the projected diagram of the particle to the area was determined as the area ratio to the circumscribed circle. Since the projected shape of the particle is very similar to a circle, it follows that the core particle is very similar to a sphere, but the area ratio with respect to the circumscribed circle is 10
Close to 0%. In the present invention, it is preferable that the area ratio determined as described above is 60% or more, preferably 70% or more. Particles with an area ratio of less than 60% have a shape that is quite different from a spherical shape, and when such particles are added, the protrusion-shaped water on the film surface obtained is irregular, and the film surface shape is It does not meet the purpose of the present invention, which is intended to prepare It111 by rectification.

Further, the amount of particles added is preferably 0.005 to 0.5 IJi% or less relative to the polymer.

More preferably, it is 0.01 to 0.5% by weight. If the amount added is less than 0.005 wtIk%, the particle haze in the polymer will be small, resulting in a low protrusion density on the film surface, resulting in insufficient IVP and abrasion resistance.

On the other hand, the amount added is 0.5 weight tons! If it exceeds 2, it causes agglomeration within one particle of the polymer, which is unsuitable in terms of the number of coarse protrusions.

The inert particles used in the present invention are not particularly limited to inorganic particles or organic particles as long as they satisfy the above conditions, but include calcium carbonate, silica resin, silicon oxide,
Barium fIt acid and titanium oxide are preferred.

The particle components of these inert particles are not limited in any way by manufacturing method or other aspects as long as they satisfy the conditions specified above, and both natural products and synthetic products can be used. Further, these particles may be used alone, but two or more particles may be used in combination.

In the method of adding inert particles to polyester in the present invention, they can be added at any stage in the polyester production process, but it is particularly preferable to add them before the initial condensation is completed. In addition, the method of adding inert particles to the polyester manufacturing process may be either in the form of a slurry or in the form of a powder, but from the viewpoint of preventing single particles from scattering, and improving the accuracy and uniformity of the particle size, it is preferable to add the inert particles in the form of a slurry. It is preferable to add it in portions, and it is particularly preferable to add it as a slurry of ethylene glycol (EG). When dividing into a slurry, it is necessary to carry out uniform fractionation so as to reproduce the original primary particles of each particle as much as possible. In order to obtain particles having a predetermined average particle size, classification of commercially available ammonium granules, p-filtration, and other treatments may be employed.

(Example) Next, Examples and Comparative Examples of the present invention will be shown. All parts in the examples mean parts by weight unless otherwise specified.

In addition, the measurement method used is shown below.

(1) The average particle size of inert particles was measured using a scanning electron beam (Hitachi S-510
Observe and photograph the cedar using a mold) and make an enlarged copy of it.

Further tracing was performed and 200 particles were randomly painted black. This image was placed in an image analyzer (Luzex Model 500, manufactured by Reco Co., Ltd.) to measure the diameter of the particles in the horizontal direction, and the average value was taken as the average particle diameter. Also 5
The degree of variation in particle diameter was calculated using the following formula.

(2) Randomly select 20 particles from the trace image used to measure the area ratio average particle diameter with respect to the circumscribed circle, and calculate the projected cross-sectional area of each particle by (
It was measured using the image analysis device used in 1).

In addition, the area ratio ftyK was determined using the above formula by calculating the area of the circle enclosing the particles of Sell et al.

(3) Surface flatness of the film Surfcom 300A type surface roughness #t (manufactured by Tokyo Seimitsu), needle F41tstn, weight 0.07f, fA5 constant reference length Q, 81m, cutoff 0.0811. The measured center line average roughness is expressed as RA (μtN)).

(4) Processability of film (sliding and abrasion resistance)
Gold FA is a tape-like roll of film slit into narrow widths.
When the tape is rubbed against a manufactured guide roll and run at high speed for a long period of time, the magnitude of the tape tension after the guide roll is rubbed and the amount of white powder generated on the guide roll surface are evaluated on a five-point scale for a constant supply tension. Expressed by ranking.

(B) Slip Note Grade 1: High strength (many scratches) Grade 2: Tension and medium thickness (quite a lot of scratches) Grade 3...
Medium tension (slightly scratches) Grade 4...Tension somewhat low (no scratches) Grade 5...
・Low tension (no scratches) (b) Abrasion resistance 1'4&... Very much white powder, grade 2 °・° Grade 3, with a lot of white powder... Grade 4, with some white powder...・No white powder generation at all Grade 5... No white powder generation at all 5) Durability Running property Using the equipment shown in Figure 1, the rough surface of a polyester film was coated in an atmosphere of 23°C and relative humidity of 65°C. The side surface was prepared using a commercially available household VTR guide bottle (maximum protrusion height measured with a stylus type surface roughness needle was 0.15 μm, center line average roughness was o).
, o o s μm) at an angle of 3/4π (unit: radian), and a constant load of 50 grams of tension was applied to the crank at an angular velocity of 8. The increase (Δμ
kd and Δμks) 1 to 5 and expressed as a first-order ranking.

1st class: Increase in friction coefficient 0.20 or more 2nd class: 0.
15-0.20 3rd grade...0.10-0.15 4th grade...0.05-0.10 5a...less than 0.05 (6) Number of coarse protrusions on the film surface Aluminum on the film surface After thinly vapor-depositing, the number of coarse protrusions larger than quadruple rings (number per 1 measurement area) was counted using a two-beam interference @Kin mirror.

The following rankings are used depending on the number of coarse protrusions.

1st grade...16 or more pieces/- 2nd grade...2 to 15 bows/- 3rd grade...8 to 11 pieces/tzJ 4th grade...4 to 7 pieces/- 5th grade...0 to 3 units/1 Example 1 A continuous esterification reactor consisting of a two-stage complete mixing chamber equipped with a decentralized stirring device, two raw material inlets, and a product outlet was used, and the first esterification reactor was The molar ratio of ethylene glycol (EG) to terephthalic acid (TPA) was adjusted to 1.7 in a system containing an esterification reaction product, and antimony trioxide was used as an antimony atom to form TPA.
An EG slurry of TPA containing 9289 ppm per unit was continuously fed.

At the same time, the EG bath solution of magnesium acetate tetrahydrate and the EG solution of sodium acetate ft are passed through the reactor from a supply port other than the TPA EG Softfree supply port.
PP and Na atoms were continuously supplied so that the total concentration was 10 ppm, and the average residence time was 4.5 hours at normal pressure, and the temperature was 2.
The reaction was carried out at 55°C.

This reaction product is continuously taken out of the system.

It was supplied to the second esterification reactor. The polyester unit in the reaction product passing through the second esterification reactor contains 0.5 kM parts of EG, 64 ppm as EG solution #1 kPM of J methyl phosphate and an average particle size of 1 .1 μm and the degree of variation in particle size is 1
700 ppm of spherical silica EG slurry with an area ratio of 94% to the circumscribed circle as silicon dioxide.
Continuously supplied from separate supply ports so that the average return time was 5.0 hours at normal pressure, 1 ML degree, 260°C.
I reacted with

The esterification rate of the reaction product in the 881st esterification reactor was 70%, and the esterification rate of the reaction product in the second esterification reactor was 98%.

The esterification reaction product was mixed with a stirring device for 1 minute at 111F! I
! .

Polycondensation was carried out by continuously feeding the mixture into two continuous polycondensation reactors each equipped with a 2-liter raw material inlet and a product outlet to obtain a polyester having an intrinsic viscosity of 0.620. The polymer and the polymer were melt extruded at 290°C and extruded at 90°C.
Table 1 shows the properties of a 15 μm film obtained by stretching 3.5 times in the longitudinal direction at 130°C and 3.5 times in the transverse direction at 130°C and then heat-treating at 220°C. The number of coarse protrusions is extremely small,
And easy m t! +: It can be seen that the quality is extremely high due to the p and running durability.

Comparative Examples 1 and 2 A case in which spherical silica with an average particle diameter of 0.96 μm, a particle size variation degree of 34%, and an area*94% was used in the method of Example 1, and a case in which spherical silica was used in the method of Example 1, and a case in which spherical silica was used with an average particle diameter of 0.96 μm, a particle size variation degree of 34%, and an area ratio of 56%. % amorphous silica was used in the same manner as in Practical Example 1. Table 1 shows the custom-made Toku-9 film. The film obtained in this comparative example is of low quality, with poor slipperiness and abrasion resistance, and a large number of coarse protrusions.

Example 2 A film obtained in the same manner as in Example 1 except that 1,001,000 pp of spherical silica with an average particle diameter of 0.32 μm and a particle size dispersion of 14×1 area ratio of 96% was added. The custom-made film is shown in Table 1. In this example, it can be seen that although the warm film is very smooth, it has relatively excellent sliding property 2 and abrasion resistance.

Comparative Example 3 Table 1 shows a custom-made film obtained in the same manner as in Example 2 except that spherical silica having a degree of variation of 32% was used. The film obtained in this comparative example had a coarse protrusion count of 1. Both slipperiness and abrasion resistance were somewhat unsatisfactory.

Below is a margin (effects of the invention) According to the present invention, 1 inert particles with adjusted particle size and shape! l:
By adding particles, an oriented polyester film having the following excellent properties can be obtained.

(1) The film has excellent processability, ie, lubricity and shore abrasion resistance.

('2) The number of coarse protrusions on the film surface is small.

(3) Pay close attention to the shape and height of the protrusions on the film surface! !
E can be adjusted.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a tape tester for measuring the repeated running performance of a rough film surface. Each part will be briefly explained below. 1: Crank 2.4, 6, 8: Free low 3.7: Tension detection device 58 Commercially available VTR guide pin 9: Load

Claims (1)

[Scope of Claims] The average particle diameter is 0.05 μm or more and less than 5.0 μm, the degree of variation in particle diameter is 25% or less, and the area ratio with respect to the circumscribed circle defined by the following formula is 60% or more. An oriented polyester film containing 0.005% by weight or more and 0.5% by weight or less of certain inert particles. [Area ratio to circumscribed circle] = (projected cross-sectional area of particle) / (
area of the circle circumscribing the particle) x 100