JPS62253631A - Polyester film - Google Patents

Abstract

PURPOSE:The titled biaxially oriented film, obtained by containing respective specific amounts of two kinds of anatase type titanium dioxide of different particle diameters, having improved surface smoothness, slipperiness, winding characteristic as well as abrasion resistance and suitable for magnetic recording tapes. CONSTITUTION:A polyester film, preferably polyethylene terephthalate based or polyethylene naphthalate based film containing (A) 0.01-1.0wt%, preferably 0.1-0.7wt% anatase type titanium dioxide having 0.01-0.30mum, preferably 0.05-0.27mum average particle diameter and (B) 0.002-0.5wt%, preferably 0.005-0.09wt% anatase type titanium dioxide having 0.31-1.0mum, preferably 0.35-0.70mum average particle diameter.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a biaxially oriented polyester film that is smooth and has highly improved winding workability.

<Prior art and problems to be solved by the invention> Polyesters, represented by polyethylene terephthalate, are used for magnetic recording and capacitors due to their excellent mechanical properties, electrical properties, chemical resistance, and dimensional stability. When polyester film is used as a base material in many fields such as printing, packaging, plate making, electrical disconnection, and photographic film, the required properties differ depending on each application, but they are universally required. The characteristic is workability when handling the film, and in order to improve this, it is necessary to reduce the slipperiness of the film, that is, the coefficient of friction.

In addition, when a magnetic layer is applied to the surface of the film as a base film for audio, video, and computer applications, which have been growing rapidly in recent years, and used as a magnetic recording medium,
If the slipperiness and abrasion resistance are poor, the friction and abrasion between the coating roll and the film surface during application of the magnetic layer will be severe, and scratches will easily occur on the film surface.

In addition, the film after applying the magnetic layer can be used for audio, video,
Even after processing it into products such as computer tape,
During winding up of drawers from reels, cassettes, etc., significant friction and wear occurs between the many guide parts, recording and playback heads, etc., and white powdery substances are generated due to scratches on the surface of the polyester film, etc. , magnetic recording layer A-
@-77'l Ara-91 V-lops 〒It is often ^10 to red 100 reasons.

In order to improve these properties required of a polyester film, a method generally employed is to add inactive fine particles to the polyester in order to impart irregularities to the surface of the film.

This method can be broadly divided into two. One of these methods is the precipitation method, in which one or more metal compounds soluble in ethylene glycol, such as calsulam compounds and lithium compounds, are added before and after the transesterification or esterification reaction to form fine particles insoluble in polyester. This is a method of precipitating it as Another method that is compared to the precipitation method is the addition method, in which calcilum carbonate, calcilum sulfate, kaolin, silica, titanium dioxide, etc. are added as they are or after being made into fine particles during polyester synthesis or molding. . Generally speaking, the larger the particle size of the particles in polyester, the greater the effect of improving lubricity, but for precision applications such as magnetic tape, especially video, the particles themselves are large, causing dropouts and other problems. Therefore, the particles contained in the polyester must be as fine as possible. However, it is currently extremely difficult to simultaneously satisfy these contradictory characteristics.

Means for Solving the Problems> The present inventors and others have discovered that as the precision of magnetic recording tapes continues to advance, improvements in the slipperiness and abrasion resistance of magnetic tape films are increasingly required. In light of the increasing demand for magnetic tapes, we have developed a complete film for magnetic tape that has a smooth film surface, excellent lubricity and abrasion resistance, fewer defects such as dropouts, and excellent workability during film production, especially in terms of winding properties. In other words, the gist of the present invention is that the average particle size is 0.0/~0.3θ
μm rutile titanium dioxide Q, 07~/, 0% by weight
and a biaxially stretched polyester film characterized by containing 0.00.2 to 0.3% by weight of anatase titanium dioxide, which is rumored to have an average particle size of 0.3/ to 7.0μ.

The present invention will be explained in detail below.

The polyester referred to in the present invention refers to an aromatic dicarboxylic acid such as terephthalic acid, isophthalic acid, naphthalene, 6-dicarboxylic acid, or an ester thereof and a glycol such as ethylene glycol, diethylene glycol, tetramethylene glycol, neopentyl glycol, etc. It is a polyester that can be obtained by polycondensing.

Polyester can be obtained by direct polycondensation of aromatic dicarboxylic acid and glycol, or by polycondensation after transesterification of aromatic dicarboxylic acid dialkyl ester and glycol, or by polycondensation after polycondensation of aromatic dicarboxylic acid dialkyl ester and glycol. It can also be obtained by methods such as polycondensation.

Typical examples of such polymers include polyethylene terephthalate and polyethylene-296-naphthalate. This polymer may be a homopolymer or may be a copolymer of a third component. In any case, in the present invention, polyesters having ethylene terephthalate units and/or ethylene co,/--naphthalate units of Sθ mol or more are preferable. The purpose is to add specific amounts of anatase titanium dioxide.

The average particle size of anatase titanium dioxide, which has a small particle size, is 0. θ/~0. ．． It needs to be 30 μm, and more preferably the average particle size is 0.05 to θ and 27 μm.

If the average particle diameter is less than 0.074 m, the effect of improving lubricity and abrasion resistance will be insufficient, so it is not preferable. On the other hand, if the average particle size is 0. .: If it exceeds 10 μm, the smoothness of the film surface decreases and large particles, which cause dropouts, increase, which is not desirable.

The amount added to polyester is 0.0/~~/, O
It is necessary to make it wt%, and preferably the amount added is Q, /~
θ. 711% is good. If the amount added is less than 7wt4, the effect of improving slipperiness and abrasion resistance will be insufficient, which is not preferable. Conversely, the amount added is i.

If it exceeds 11%, it is not preferable because the smoothness of the film surface decreases and the contamination of coarse particles that causes dropouts increases.0 The average particle size of anatase titanium dioxide with a large particle size is 0.37~ The average particle diameter θ is preferably in the range of 35 to 0.70 μm. Average particle size 0
．． If the thickness is less than 37 μm, the effect of improving wear resistance and winding properties will be insufficient, which is not preferable. If the average particle size exceeds a density of /0μ, the smoothness of the film decreases and the number of large particles, which causes dropouts, increases, which is not preferable.

Further, the amount added to the polyester is 0.00 to 0,
s Must be 11%, preferably o, o o
s~0.3wt%, preferably 0.00! t~
-0.09vtt%. Addition amount is 0.002vt%
If it is less than 11%, the improvement effect on abrasion resistance and winding properties will be insufficient, so it is undesirable. If it exceeds 11%, the smoothness of the film surface will decrease and the roughness will cause dropouts. This is not preferred because it increases the amount of particles mixed in.

In order to improve lubricity, wear resistance and winding properties, the difference in average particle size between small particle size anatase type titanium dioxide and large particle size anatase type titanium dioxide should be at least 0.70.
It is desirable that the thickness is μm or more.

The anatase-warm titanium dioxide used in the present invention is not limited in any way, including its manufacturing method, as long as it satisfies the conditions specified above. Moreover, a material without surface treatment may be used, or a material with surface treatment may be used. ◇ Regarding the volume shape coefficient, it is preferable to use a material whose value is in the range of 0.70 to π/6.

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

IP-V/D" where V is the particle volume (μm") and D is the maximum diameter (μm) of the particle in the projected plane. ] The volume shape factor represents the degree of sphericity of the particle, and is π/
The closer it gets to 6, the more spherical it becomes.

The average particle size here refers to the cumulative (
Weight basis) Use the value of rOchi.

The titanium dioxide used in the present invention is preferably added after the esterification reaction and before the polycondensation.

However, when adding particles to the polyester manufacturing process, it is usually preferable to add the particles as an ethylene glycol slurry from the viewpoint of automation, ease of metering, improved dispersibility, and simplification of the recovery system. Common. When dispersing particles into a slurry, it is necessary to disperse them into a state of primary particles with as little agglomeration as possible. In this way, in order to uniformly disperse the particles to the state of primary particles, any method such as dispersion, crushing, pulverization, classification, F3m, etc. can be adopted as necessary. Also, particles with a predetermined average particle size can be used. In order to obtain this, methods such as pulverization, classification, and filtration of reprinted particles may be employed.

When adding the particles as an ethylene glycol slurry,
It is particularly preferable to add coarse particles of 2 μm or more in the slurry at a ratio of o, r weight % or less based on the total particles in order to reduce coarse protrusions on the surface of the film when it is made into a polyester film.

Large particles and small particles can be incorporated into polyester by simultaneously adding a predetermined amount of particles of different particle sizes during polyester production, or by separately producing particles of different particle sizes. An example of this is a method in which the components are mixed at the time of film formation, but any method may be used.

In the present invention, if necessary, inert particles may be added in addition to titanium dioxide as long as the average particle size and content are such that they do not increase the number of coarse particles and do not adversely affect the smoothness of the film surface. May be used together. In addition to the above-mentioned inert particles, fine particles precipitated by a reaction between a catalyst residue and a phosphorus compound in the reaction system can be used in combination.

In the present invention, known methods can be employed for polymerizing the polyester containing titanium dioxide. For example, as a catalyst for polycondensation reaction, one or more of antimony compounds, germanium compounds, titanium compounds, etc. are used, and 2Jθ~J
The reaction is allowed to proceed by heating to about CJO°C and distilling off ethylene glycol under reduced pressure.

In addition, when forming a film, a known film forming method such as 27
After melt-extruding polyester chips into a film at 0 to 3θθ℃, solidify after cooling at θ to 70℃ to form an amorphous sheet, and then sequentially or simultaneously biaxially stretched vertically and horizontally.
Methods such as heat treatment at 0°C (for example,
fl)-j6j? (method described in the above publication) can be adopted.

<Examples> Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples without exceeding the gist thereof.

In addition, various physical properties and characteristic lines are measured or defined as follows. “Part” in Examples
and "chi" mean "1 part by weight" and "part by weight", respectively.

(1) Average particle size Centrifugal sedimentation type particle size distribution measuring device 5A-CP manufactured by Shimadzu Corporation,
? 〇(2) Surface smoothness of film J Engineering S B80/-/971. Using the integrated (weight-based) 3θ value in the equivalent spherical diameter distribution measured by the shape. According to the method described.

The measurement was carried out using a surface roughness measuring machine model SE-71! ' (manufactured by Koita Institute). Stylus diameter μ, stylus pressure 30mg
g, cutoff value 0. Ottawa, and the measurement length was set to 1. Measurement was performed at 72 points, the maximum value and minimum value were cut, and the average value of 102 points was shown.

(3) Smoothness is represented by the coefficient of friction, and the coefficient of friction is ASTMD-/ff? ≠
The sample size at the time of 0 measurement, which was modified to allow measurement with a tape-shaped sample according to the above method, was width/jm, length 15θ, and the tensile speed was 10-. The measurements were carried out in an atmosphere with a temperature of C/C and a humidity of 6J±5%.

(4) Abrasion properties (evaluation of white powder) The film was run over a length of 500m using the running system shown in FIG. 1, and the amount of wear attached to the hard chrome fixing bottles in the 6th order shown in (I) was visually evaluated.

No adhesion at all ○ Slight adhesion Δ Large amount of adhesion × (5) Winding characteristics The appearance of the roll surface and roll end face when wound up into a roll was evaluated as follows.

There are almost no wrinkles or bulge-like defects on the roll surface, and the roll edges are evenly aligned: ○There are almost no wrinkles on the roll surface, but there are some bulge-like defects, and the roll end surfaces are slightly uneven. Items: Δ Wrinkles on the roll surface or roll end faces that are uneven; .

Measurement wavelength O, S≠ μm The number of protrusions in the interference group of the first order or higher is converted per 2 d. Example 1: 100 parts of dimethyl terephthalate, 60 parts of ethylene glycol, and 0.0 parts of magnesium acetate. 0? A portion of the mixture was placed in a reactor and heated to 230° C., substantially completing the transesterification reaction. Then, the average particle diameter θ1.
2S μm small particle anatase type titanium dioxide is pre-dispersed in ethylene glycol, classified and over-treated, and large particle anatase type titanium dioxide with an average particle diameter of o, p s μm is pre-dispersed in ethylene glycol. After thoroughly mixing and adding 0.0 wt% of ethyl acid phosphate dispersed, classified, and overtreated, ethyl acid phosphate
, 0 parts of o lI, 0 parts of antimony dioxide, and 5 parts of Oj were added and polycondensation was carried out for several hours to obtain a polyethylene terephthalate resin having an intrinsic viscosity of 0.66.

The properties of the obtained polyester film are shown in */Table.

As shown in Table 1, the obtained film had very good surface smoothness, lubricity, abrasion resistance, winding properties, and number of coarse protrusions, and was at an extremely satisfactory level as a film for magnetic tape. .

The small particle anatase type used in the implementation example/
A lever-stretched polyester film was obtained in the same manner as in Table 1. The properties of the obtained polyester film are shown in Table 1. The properties of the obtained film were the same as those of Example 1. Comparative Example 1 Anatase titanium dioxide with an average particle size of 0.25 μm was predispersed in ethylene glycol, classified and filtered, and then θ,,ywt A biaxially stretched polyester film was obtained in the same manner as in Example 1 except that only % was added.

The properties of the obtained polyester film are shown in Table 1.
As shown in Table 1, the resulting film had poor abrasion resistance and winding properties, and was insufficient for magnetic tape properties.

Comparative Example λ 7 Natase type titanium dioxide with an average particle size o of 4 cs μm was previously dispersed in ethylene glycol, classified and overtreated, and 060% by weight was added with vinegar alone. A biaxially stretched polyester film was obtained by this method. The properties of the obtained polyester film are shown in Table 1. As shown in Table 1, the obtained film has poor slip properties, abrasion resistance, and winding properties, and is insufficient as a magnetic tape property. Comparative Example 3 Small particles with an average particle size of O, Sμm Anatase-type titanium dioxide is pre-dispersed in ethylene glycol, classified and filtered. Large particles of anatase-type titanium dioxide with wt% and average particle diameters of o and qs μm are pre-dispersed in ethylene glycol, classified and filtered. A biaxially stretched polyester film was obtained in the same manner as in Example 1, except that 0.07 wt% of the polyester resin was thoroughly mixed and added. The properties of the obtained polyester film are shown in Table 1. As shown in Table 1, the obtained film has satisfactory properties in terms of slipperiness and abrasion resistance, but it is inferior in terms of winding properties and the number of coarse protrusions, and is insufficient for use in magnetic tapes. be.

Comparative Example Small particle anatase type titanium dioxide with a Hiroshima average particle diameter of 0.5 μm was fractionally treated in ethylene glycol in advance, classified, -
The over-treated material is 0.3 wt% and the average particle size Q, lIj
0.7μm large particle anatase titanium dioxide dispersed in ethylene glycol, classified and filtered.
A biaxially stretched polyester film was obtained in the same manner as in Example except that the wt% was sufficiently mixed and added. The properties of the obtained polyester film are shown in Table 1.As shown in Table 1, the obtained film has satisfactory lubricity and abrasion resistance, but it has poor winding properties and coarse protrusions. They are inferior in number and are insufficient for magnetic tape applications.

<Effects of the Invention> As detailed above, the film of the present invention is a film containing specific amounts of small-particle anatase-type titanium dioxide with a specific particle size and large-particle anatase-type titanium dioxide with a specific particle size, It has the characteristics of excellent surface smoothness, slipperiness, and workability during film production, which are required for a polyester film for magnetic tapes, especially in terms of winding properties. It also has excellent abrasion resistance, and has a characteristic that the amount of white powder generated when running on the metal roll surface during magnetic tape manufacturing and magnetic tape use is extremely small, and there is no dropout when used for video cheese. Since it has the characteristic of having a significantly small number of coarse protrusions that cause generation, it can be used in a wide range of applications such as magnetic tapes, vapor deposition, capacitors, and packaging.

[Brief explanation of drawings]

Figure 7 is a schematic diagram showing the running system for evaluating wear resistance.
In the figure, (I) indicates 10 hard chrome fixing bottles, (■) indicates a tension meter, and σ is /JO''. Agent: Patent Attorney Cho Kagawa - Others/Names

Claims (1)

[Claims] (1) 0.01 to 1.0 wt% of anatase titanium dioxide with an average particle size of 0.01 to 0.30 μm and 0.002 to 1.0 wt% of anatase titanium dioxide with an average particle size of 0.31 to 1.0 μm Biaxially oriented polyester film characterized by containing 0.5 wt%