JPS63254135A - Polyester film - Google Patents

Abstract

PURPOSE:To obtain a biaxially oriented polyester film having excellent slipperiness and chipping resistance, by containing spherical fine particles and cocoon- shaped fine inert particles. CONSTITUTION:A biaxially oriented film containing (A) spherical fine particles and (B) cocoon-shaped fine particles at a weight ratio to satisfy the formula 0.01<=A/B<=100 (A and B are weight). The round fine particles having the average major axis (DAL) and average minor axis (DAW) and cocoon-shaped fine particles having the average major axis (DBL) and average minor axis (DBW) expressed by the formulas 0.1mu<=DAL<=5mu, 1.0<=DAL/DAW<=1.2, 0.1mu<=DBL<=5mu and 1.4<=DBL/DBW<=1.9 are used. The total amount of the components (A) and (B) is 0.01-5wt.%. Silica, titanium dioxide or silicone is used as the components (A) and (B).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a polyester film, and more particularly to a biaxially oriented polyester film containing fine particles having a specific shape and having excellent slip properties and abrasion resistance.

[Prior Art] Polyester films, represented by polyethylene terephthalate films, have excellent physical properties.

Because of its chemical properties, it is used in a wide range of applications, such as magnetic tape, condensers, photography, and packaging.

It is used for 0f-IP etc.

In a polyester film, its slipperiness and abrasion resistance are major factors that determine the workability of the film manufacturing process and processing process in each application, as well as the quality of the product.

If these are insufficient, for example, when applying a magnetic layer to the surface of a polyester film and using it as a magnetic tape,
During application of the magnetic layer, the friction between the rolling roll and the surface of the film is intense, and the surface of the film is also abraded, and in extreme cases, wrinkles, scratches, etc. may occur on the surface of the film.

In addition, even after the magnetic layer and coated film are slit and processed into audio, video or computer tapes, etc., many guide parts, playback heads etc. Significant wear occurs between the polyester film, causing scratches, distortion, and even white powder deposits due to scratches on the surface of the polyester film, which is often a major cause of missing magnetic recording signals, that is, dropouts. .

Conventionally, many methods have been proposed to reduce the friction coefficient of polyester by adding fine particles to the polyester, but the affinity between the fine particles and the polyester is insufficient, and the transparency and abrasion resistance of the film deteriorate. was also not satisfactory. To further explain this method, as a means to improve the surface properties of polyester,
□Conventional ■ A method in which part or all of the catalyst used during polyester synthesis is precipitated during the reaction process (internal particle precipitation method) ■ A method in which fine particles such as calcium carbonate or silicon oxide are added during or after polymerization (external particle precipitation method) A number of methods have been proposed.

However, in the internal particle precipitation method (2), since the particles are metal salts of the polyester component, the affinity with polyester is good to some extent, but on the other hand, the method generates particles during the reaction, so the amount of particles is 2 particles. It is difficult to control the size of the particles and prevent the formation of coarse particles.

On the other hand, in the method (2), if the particle size, amount added, etc. are appropriately selected, and if coarse particles are added with fine particles from which coarse particles have been removed by a sieving machine, excellent lubricity can be achieved.

However, since the affinity between the inorganic particles and the organic component polyester is not sufficient, peeling occurs at the interface between the particles and the polyester during stretching, etc., and voids are generated.

If these voids exist in the polyester film, they may cause contact between the polyester films or between the polyester film and other groups, or particles may easily separate from the polyester film due to damage to the polyester film, for example. Like small particles, it causes white powder and dropouts in magnetic tape films. Furthermore, the presence of large voids around the particles impairs the transparency of the polyester film. Therefore, the lack of affinity between inorganic particles and polynisdel is a problem that must be solved in terms of wear resistance and transparency.

To improve the affinity between inorganic particles and polyester, surface treatment using a coupling reaction between inorganic particles and silane compounds or titanate compounds, for example, has been proposed, but the treatment process is complex and the effects are not expected. There were various problems such as not being able to cut the edges.

[Purpose of the invention] In view of the above-mentioned circumstances, the inventors of the present invention have investigated the slipperiness.

Excellent abrasion resistance and the shape of the protrusions on the film surface.

As a result of extensive research in order to obtain a biaxially oriented polyester film that has excellent size distribution, etc. and has properties suitable for various uses, we have found that a polyester film containing particles with a specific shape can be created by combining particles and polyester. It has been discovered that the peeling at the interface between the two is improved and the film has good characteristics, and the present invention has been achieved.

Therefore, an object of the present invention is to provide a biaxially oriented polyester film with small voids and excellent slipperiness and abrasion resistance.

-〇- [Structure/effect of the invention] According to the present invention, an object of the present invention is to provide polyester with
This is achieved by a biaxially oriented polyester film characterized by containing true spherical fine particles (A) and cocoon-shaped fine particles (8) in an amount ratio satisfying the following formula %.

The polyester in the present invention is a polyester containing an aromatic dicarboxylic acid as a main acid component and an aliphatic glycol as a main glycol component.

Such polyesters are substantially linear and have film forming properties, particularly by melt molding. Examples of aromatic dicarboxylic acids include terephthalic acid,
Examples include naphthalenedicarboxylic acid, isophthalic acid, diphenylethanedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic phenylsulfonedicarboxylic acid, and anthracenedicarboxylic acid. Examples of aliphatic glycols include ethylene glycol, trimethylene glycol, and tetramethylene glycol.

Examples include alkylene glycols having 2 to 10 carbon atoms such as pentamethylene glycol, hexamethylene glycol and decamethylene glycol, and alicyclic diols such as cyclohexane dimetatool.

In the present invention, examples of the polyester include alkylene terephthalate and/or alkylene naphthalate-1 to
Preferably, the main component is

Among such polyesters, for example, not only polyethylene terephthalate and polyethylene-2,6-naphthalate, but also terephthalic acid and/or 2,6-naphthalenedicarboxylic acid account for 80 mol% or more of the total dicarboxylic acid component, and all glycol A copolymer in which 80 mol% or more of the components is ethylene glycol is preferred. In this case, up to 20 mol% of the total acid component can be the above-mentioned aromatic dicarboxylic acids other than terephthalic acid and/or 2,6-naphthalene dicarboxylic acid, and also aliphatic dicarboxylic acids such as adipic acid, cepatic acid, etc. ; It can be an alicyclic dicarboxylic acid such as cyclohexane-1,4-dicarboxylic acid. In addition, up to 20 mol% of the total glycol component can be the above-mentioned glycols other than ethylene glycol, or aromatic diols such as hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane, etc.; , 4-dihydroxymethylbenzene and other aliphatic diols having an aromatic ring: polyethylene glycol, polypropylene glycol.

It can also be a polyalkylene glycol (polyoxyalkylene glycol) such as polytetramethylene glycol.

Furthermore, in the polyester used in the present invention, a component derived from an oxycarboxylic acid such as an aromatic oxyM:ω-hydrococicaproic acid such as hydroxybenzoic acid, a dicarboxylic acid component and an oxycarboxylic acid component such as an aliphatic oxyacid such as ω-hydrococcaproic acid is added. Those copolymerized or combined in an amount of 20 mol % or less based on the total amount of acid components are also included.

Furthermore, the polyester in the present invention contains a trifunctional or higher functional polycarboxylic acid or polyhydroxy compound, such as trimeriso-1-acid, in a substantially linear amount, for example, 2 mol % or less based on the total acid components. Copolymers of pentaethritol and the like are also included.

Furthermore, the polyester in the present invention includes, for example, pigments,
Other additives such as dyes, ultraviolet absorbers, heat stabilizers, light stabilizers, antioxidants, and light shielding agents (eg, carbon black, titanium dioxide, etc.) can also be included as required.

The truly spherical fine particles (A) referred to in the present invention preferably have a ratio of the major axis to the minor axis (major axis/minor axis) of 1.0 to 1.2, and the average major axis (D^[) and the average The particle size ratio (D AL/D AW) to the short diameter (with DA) is also i. o~1
, 2 is preferable. In addition, when the true spherical fine particles referred to in the present invention are defined by the following volume shape coefficient, 0.36
- π/6 is preferable.

(2) φ-□ The average diameter of such truly spherical fine particles is preferably 0.1 to 5μ, more preferably 0.2 to 2μ. In addition, in order to sharpen the distribution of protrusions on the film surface, the relative standard deviation of the particle size defined below is preferably 0.7 or less, and more preferably 0.
．． It is preferably 5 or less.

Relative standard deviation where dl: Maximum major axis of each particle (μ) D8: Number average value of maximum major axis of particles (μ) n: Number of particles.

11- The cocoon-shaped fine particles (B) referred to in the present invention are particles having a constricted shape in which spherical particles are combined.
A typical example is shown in FIG. 2, but the constriction shown in FIGS. 1-2 may have a gentle shape as shown in FIGS. 1-3.

The average minor axis (DBΔ) and average major axis (D
BL) ratio (D BL/D BW) is 1.4 to 1
．． It is preferably in the range of 9. Further, the average particle diameter of the cocoon-shaped fine particles is preferably 0.1 to 5μ, more preferably 0.2 to 2μ.
μ is preferred. Furthermore, the relative standard deviation of the long axis of the cocoon-shaped fine particles defined by the following formula is preferably 0.7 or less, more preferably 0.5 or less.

Relative standard deviation where dl: maximum major axis of each particle (μ) D [number average value of maximum major axis of two particles (μ) n is the number of two particles.

121 Average major axis (DAL) and average minor axis (DAW) of true spherical particles in the present invention, average major axis (DBL) of cocoon-shaped fine particles
), the average short diameter (DBΔ), and the relative standard deviation can be determined by photographing each fine particle with an electron microscope at a magnification of, for example, 10,000 to 50,000 times, and then measuring and calculating the respective diameters.

The true spherical fine particles and cocoon-shaped fine particles in the present invention are not particularly limited in composition as long as they are insoluble in polyester and do not substantially deform during melting or stretching of polyester, and may be organic or inorganic. good. Specific examples of true spherical particles or cocoon-shaped particles include silica and titanium dioxide.

Silicone (polyorganosiloxane) and the like are preferred due to their ease of availability and dispersibility in polyester.

The method for producing true spherical particles and cocoon-shaped particles is not limited in any way. Examples of methods for producing truly spherical fine particles include a method for producing silica by hydrolyzing ethyl orthosilicate followed by a condensation treatment; a method for producing silicone (polyorganosiloxane) by hydrolyzing organochlorosilane and then subjecting it to a condensation treatment. etc. - As a method for manufacturing Manryo-shaped fine particles, for example, as a method similar to the conditions for producing true spherical fine particles as shown below, 1 to 10 mμ
An example of a manufacturing method is to aggregate or grow ultrafine particles of about 100 mL to form primary spherical particles, and then to combine two spherical particles to further grow the particles. Even if a small amount of aggregates of three or more spherical particles generated as a by-product during production are mixed into the cocoon-shaped fine particles, there is no problem as long as the effects of the present invention are not impaired.

In the present invention, true spherical fine particles (A) and cocoon-shaped fine particles (B)
The total content of o, oi for polyester
-5% by weight is preferred, 0.05-3% by weight is more preferred, and 0.1-1% by weight is particularly preferred. Further, the weight ratio (A/B) between the true spherical fine particles (A) and the cocoon-shaped fine particles (8) in the present invention is o, oi~100, but 0.02
-50 is preferable, and 0.03-30 is especially preferable. If this weight ratio is less than 0.01, it is practically difficult to manufacture particles, and if it exceeds 100, it is essentially the same as containing only true spherical fine particles, and it is difficult to improve the abrasion resistance. There are limits in terms of

The true spherical fine particles (A) and the two-type fine particle mark) may be made of the same material or different materials, and the combination of cable materials is not particularly limited. For example, examples include a combination of silica as true spherical fine particles, silica as cocoon-shaped fine particles, a combination of silica as true spherical fine particles, and silicone as cocoon-shaped fine particles, a combination of silica and silicone as true spherical fine particles, and a combination of silicone as cocoon-shaped fine particles. can.

It is preferable to remove coarse particles from the true spherical fine particles and cocoon-shaped fine particles in the present invention using a purification process before incorporating them into polyester. Examples of the classification means include wet or dry centrifuges, filtration, and the like. Two or more of these means may be used in combination for stepwise purification.

True spherical particles and cocoon-shaped particles can be added to polyester at any time and by any method, but the best method is to add them as a glycol slurry before the polymerization reaction of the polyester reaction, especially before the end of the transesterification or esterification reaction. preferable.

For polyester film, use the above polyester as is,
Alternatively, it can be obtained by diluting it with a polyester (a polyester that does not contain true spherical particles and/or cocoon-shaped particles in a predetermined proportion) and forming a film. Other polyesters used for dilution include, for example, polyesters produced by conventional precipitation or addition methods or particle-free polyesters.

The polyester film of the present invention has unevenness units on the film surface consisting of anisotropic protrusions caused by cocoon-shaped fine particles and depressions adjacent to the protrusions, which improves the slipperiness of the film.
More preferred from the viewpoint of abrasion resistance. The shape of the unevenness unit is the second
As shown in FIG. 1 or FIG. 2-2, the anisotropic protrusion may have a depression on the long axis side or may have a depression on the short axis side of the anisotropic protrusion.

The method of forming the uneven units is that they are not formed by conventional mechanical stamping such as embossing, but are formed by deformation of the film itself during the process of stretching the film, such as the following stretching conditions: .

Formation of uneven units having depressions and depressions adjacent to the long axis side By setting the heating temperature to a low temperature and setting the stretching ratio to a high value, and then performing second axial stretching (stretching in the width direction of the film), the anisotropic protrusions caused by the cocoon-shaped particles and the long axis of these protrusions are Adjacent depressions can be formed on the sides.

Formation of uneven units having depressions and depressions adjacent to the short axis side By setting the heating to a high temperature or (and) setting the stretching ratio to a low value, and then performing second axial stretching (stretching in the width direction of the membrane), the anisotropic protrusions caused by the cocoon-shaped fine particles and this A depression can be formed adjacent to the long axis side of the protrusion.

For film stretching, the normal machine axis direction (first axis direction)
After stretching in the width direction (second axis direction), high-stage (multi-stage) stretching can be performed in which the film is further stretched in the -axis stretching direction and/or the second axis stretching direction. Even if the shape of the uneven unit consisting of the protrusions and depressions on the surface is slightly deformed, the effect of the present invention is maintained because it remains as it is.

The polyester film of the present invention has an uneven unit consisting of at least anisotropic protrusions on its surface, and in some cases, the anisotropic protrusions and depressions adjacent to the anisotropic protrusions, so that the polyester film does not come in contact with other films or with devices that come into contact with the film. The area can be reduced, and it is flat and has excellent sliding effect and wear resistance. Furthermore, compared to conventional polyester films whose surfaces have protrusions formed by mere particles, the film has the advantage of improved abrasion resistance. It should be noted that, as long as the effects of the present invention are not impaired, protrusions caused by externally added particles insoluble in polyester and/or internally precipitated particles precipitated during polyester synthesis may be used, as long as the effects of the present invention are not impaired. There is no problem even if uneven units having depressions with the particles as cores are mixed on the surface of the polyester film.

The polyester film of the present invention has various advantages such as a flat surface, excellent slipperiness, and better abrasion resistance than conventional polyester films, so it can be used for various purposes. It can be particularly preferably used in the field of magnetic tapes, etc., which require wear resistance.

[Example] Hereinafter, the present invention will be specifically explained by giving examples. In addition, each characteristic value in the Examples was measured according to the following method.

1) Particle size and shape After photographing the particles with an electron microscope at a magnification of 10,000 to 50,000 times,
The average diameter,
Find the average major axis and average minor axis.

= 19-2) Size of the depression After depositing a thin layer of aluminum on the surface of one stretched film,
Magnification of 90 using a differential interference microscope (differential interference microscope R type)
A photograph is taken at 0x magnification, and it is observed that the long diameter of the depression adjacent to the anisotropic protrusion formed by the cocoon-shaped particles is 2μ or more.

3) Film surface roughness (Ra) is a value defined in JIS'-BO601 as center line average roughness (Ra), and in the present invention, a stylus type surface roughness meter (SURFCORDER5E-30C) Measure using The measurement conditions are as follows.

(a) Stylus tip radius: 2μ (b) Measuring pressure: 30mg (C) Cutoff: 0.25mm (d) Measuring length 20.5mm (e) How to summarize the data - Repeatedly measure the data 5 times , the largest value is 1
This is expressed as the average value of the remaining four data.

4) Coefficient of friction of film (μk) Measured as follows using the apparatus shown in FIG. In Fig. 3, 1 is an unwinding reel, 2 is a tension controller, 3, 5.6, 8° 9 and 11 are free rollers, 4 is a tension detector (inlet), and 7 is a fixed rod made of stainless steel SUS 304 iR. (Outer diameter 5mmφ), 10
is a tension detector (outlet), 12 is a guide roller,
Reference numeral 13 indicates a take-up reel.

In an environment with a temperature of 20°C and a humidity of 60%, a film cut to a width of 172 inches was held with a fixing rod of 7 (surface roughness 0.3 μm).
angle θ-(152/180)π radians (152°)
and move (friction) at a speed of 200 c/min. The outlet tension when tension controller 1 to roller 2 are adjusted so that the inlet tension T1 is 35g (
T2:g) is detected by the outlet tension detector after the film has traveled 90 m, and the running friction coefficient μk is calculated using the following formula.

μk −(2,303/θ) log (T2/T
I ) = 0.8681 IOg (T2/35) 5) Abrasion evaluation - ■ A 172 inch wide film surface was brought into contact with a 5 mmφ stainless steel fixing pin (surface roughness 0.58) at an angle of 150°, and the speed was 2 m/min. It is moved back and forth about 15 cm at a speed of about 15 cm, causing friction (at this time, the tension T1 on the entry side was set to 60 g).

This operation is repeated, and after 40 reciprocating measurements, the degree of scratches that have occurred on the rubbed surface is visually determined.

At this time, there are almost no scratches.

Judgment is made on a four-point scale: ◯ if there are few scratches,

6) Evaluation of abrasion resistance - ■ The abrasion resistance of the running surface of the film is evaluated using a 5-stage mini super calendar. The calendar is a 5-stage calendar with nylon rolls and steel rolls, and the processing temperature is 8.
At 0℃, the linear pressure applied to the film is 200KCI/Cm,
The film was run at a speed of 50 m/min. After running the running film for a length of 4000 m, the abrasion resistance of the film was evaluated based on the dirt that adhered to the top roller of the calendar.

4-level judgment> ◎ No stains on the nylon roll ○ Almost no stains on the nylon roll △ Nylon roll gets dirty × Nylon roll is very dirty Example 1 Spherical silica with an average major axis of 0.5 μ and an average minor axis of 0.45 μ
．． Polyethylene terephthalate with an intrinsic viscosity of 0.60 dl/g (orthochlorophenol, 35°C) containing 1% by weight and 0.1% by weight of both types of silica with an average major axis of 0.8 μ and an average minor axis of 0.5 μ After drying at °C,
The mixture was melt-extruded at 290°C and rapidly solidified on a casting drum maintained at 40'C to obtain an unstretched film.

Subsequently, the unstretched film was preheated to 70°C with a heating roller, and then heated with an infrared heater and rolled in the longitudinal direction for 3
．． It was stretched 6 times. 4. Laterally at a temperature of 90°C.
After stretching to 0 times, heat treatment is performed at 200℃, and the thickness is 15
A film of μ was obtained.

The properties of this film are shown in Table 1, and it had a low coefficient of friction and good abrasion resistance.

Examples 2 and 3 A film was obtained in exactly the same manner as in Example 1 except that the stretching conditions for the unstretched film were changed as follows.

In the case of Example 2, after preheating the unstretched film to 60°C with a heating roller,
While heating with an infrared heater, the film was stretched 4°6 times in the longitudinal direction. Subsequently, the film was stretched at 3.4 times in the transverse direction at a temperature of 90°C.

In the case of Example 3, after preheating the unstretched film to 90°C with a heating roller,
While heating with an infrared heater, the film was stretched 3.3 times in the longitudinal direction. Subsequently, it was stretched 3.4 times in the transverse direction at a temperature of 105°C.

In both of these two types of films, anisotropic protrusions caused by the preformed silica and depressions adjacent to the protrusions were observed. Example 2 had depressions in the long axis direction of the anisotropic protrusions, and Example 3 had depressions in the long axis direction of the anisotropic protrusions. There was a depression in the short axis direction of the anisotropic protrusion.

The properties of these films are shown in Table 1, and although they had low surface roughness Ra, they had small coefficients of friction and good abrasion resistance, which was equivalent to or better than that of Example 1.

Examples 4 to 6 and Comparative Example 1 A film No. 19 was prepared in the same manner as in Example 1 except that the particle sizes and contents of the spherical silica and the double-type silica were changed as shown in Table 1. The properties of the obtained film are shown in Table 1.

Comparative Examples 2 and 3 Films were obtained in exactly the same manner as in Examples 1 and 2, except that both types of silica were replaced with calcium carbonate (average particle size: 0.5μ, 0.25% by weight), which is ordinary bulk particles. . The surface projections of the obtained film had no anisotropy. The properties of the obtained films are shown in Table 1, and the properties were poor in all cases.

Examples 7 and 8 Films were obtained in exactly the same manner as in Example 1, except that the double-type silica was replaced with double-type titanium dioxide or double-type silicone having the average major axis and average minor axis shown in Table 1. The properties of the obtained film are shown in Table 1, and all were excellent.

[Brief explanation of drawings]

FIG. 1 shows the shape of cocoon-shaped fine particles, and shows the shapes of 1-1. Part 1-2
The figure is a model diagram where the short axis is the same but the long axis is different. FIG. 1-3 is a diagram when the constriction of FIG. 1-2 is gentle. FIG. 2 is a plan view of an asperity unit of anisotropic protrusions caused by cocoon-shaped fine particles on the film surface and depressions in contact with the protrusions. The shaded area indicates a depression, and Figure 2-1 shows an uneven unit having a depression in the long axis direction of the anisotropic protrusion, and Figure 2-2 shows an uneven unit having a depression in the short axis direction of the anisotropic protrusion. It is. FIG. 3 is a schematic diagram of an apparatus for measuring the coefficient of dynamic friction (μk) of a film. = 28- Procedural amendment June 2, 1986

Claims (1)

[Claims] 1. True spherical fine particles (A) and cocoon-shaped fine particles (B) are contained in polyester according to the following formula: 0.01≦A/B≦100 [Here, A and B are true spherical fine particles ( A), cocoon-shaped fine particles (
B) represents the weight. ] A biaxially oriented polyester film characterized by containing the following in a satisfying ratio. 2. Average major axis (DAL) and average minor axis (DAL) of true spherical fine particles
DAW) and the average major axis (DBL) and average minor axis (DBW) of the cocoon-shaped fine particles satisfy the following formula. 0.1 (μ)≦DAL≦5 (μ) 1.0≦DAL/DAW≦1.2 0.1 (μ)≦DBL≦5 (μ) 1.4≦DBL/DBW≦1.9 3. The biaxially oriented polyester film according to claim 1, wherein the total content of the true spherical fine particles (A) and the cocoon-shaped fine particles (B) is 0.01 to 5% by weight based on the polyester. 4. The true spherical fine particles (A) and the cocoon-shaped fine particles (B) each contain at least one of silica, titanium dioxide, and silicone.
The biaxially oriented polyester film according to any one of claims 1 to 3, which is a seed.