JPH06322152A - Polyester film - Google Patents

Abstract

PURPOSE:To obtain the subject film consisting essentially of a specific polyester, forming fine projection on the surface, excellent in abrasion resistance and effect for suppressing occurrence of powder in travelling a roll made of plastic and having biaxial orientation. CONSTITUTION:The objective film is a biaxially oriented film consisting essentially of a polyester A composed partially or wholly of a thermoplastic resin having <=70 deg.C crystalline parameter DELTATcg and has <=20, preferably <=15 ratio (Rt/Ra) of surface roughness Ra and Rt of at least either one surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film, and more particularly to a polyester film having fine projections formed on its surface.

[0002]

2. Description of the Related Art A polyester film containing substantially spherical silica particles derived from colloidal silica in order to form fine projections on the film surface is known (for example, JP-A-59-171623). Gazette). Further, a polyester film in which a thin layer containing particles for forming surface protrusions is laminated on a base layer is also known (for example, JP-A-2-77431).

[0003]

Polyester films are widely used for various purposes. However, the above conventional polyester film, the film processing step,
For example, when the roll used in the printing process in packaging applications, the magnetic layer application step in magnetic media applications, VTR running, or the thermal transfer layer application in thermal transfer applications is a metal, the film is not scratched, so-called good. However, when the roll is made of plastic, it has become a problem that powder generated by the roll being scraped by running adheres to the roll when the roll is made of plastic.

An object of the present invention is to solve the above problems and to provide a polyester film which does not generate powder even when running on a plastic roll at a high speed while maintaining the abrasion resistance of the film itself.

[0005]

The polyester film of the present invention for this purpose is a biaxially oriented film containing polyester A as a main component, and the polyester A is partially or wholly crystalline parameter. ΔTcg is 70
It is made of a thermoplastic resin having a temperature of not more than 0 ° C. and has a ratio of surface roughness Ra to Rt of at least one surface of the film, Rt / Ra of 20 or less.

The type of thermoplastic resin that constitutes a part or all of the polyester A is not particularly limited, but the crystallization parameter ΔTcg is 70 ° C. or lower, preferably 60 ° C. or lower, and more preferably 55 ° C. or lower. is necessary. If the crystallization parameter ΔTcg is larger than the above range, abrasion resistance and powder generation on the film surface become poor, which is not preferable. The heat of fusion (change in enthalpy of fusion) measured by a differential scanning calorimeter of polyester A is 7.5 cal.
When the crystallinity is not less than / g, abrasion resistance and powder generation are further improved, which is extremely desirable. Two or more kinds of polyesters may be mixed, or a copolymerized polymer may be used, as long as the present invention is not impaired.

As the polyester A, the crystal nucleating agent effect is enhanced by devising the catalyst composition at the time of polymerization,
The use of polyethylene terephthalate having a small Tcg value is particularly effective in obtaining the film of the present invention.

As an example, it is particularly preferable to use antimony trioxide as a polymerization catalyst, magnesium acetate as an ester exchange catalyst, and a phosphonate such as dimethylphenylphosphonate as a phosphorus compound in order to achieve the object of the present invention. The method for producing the polyester A is not limited to the above.

The polyester film of the present invention need not contain particles such as inorganic or organic particles, but may contain them. However, the concentration at that time is 1% or less with respect to the total weight of the polyester A, and preferably 0.
When it is 5% or less, powder generation becomes better, which is desirable.

The film of the present invention contains the above composition as a main component, but may be blended with other polymers within a range not impairing the object of the present invention, and may also contain an antioxidant, a heat stabilizer and a lubricant. Organic additives such as UV absorbers and antistatic agents may be added to the extent that they are usually added.

The polyester film of the present invention may be used as a single layer of a biaxially oriented film containing polyester A as a main component, or as a laminated film laminated on at least one side of a film containing polyester B as a main component. You may be asked.

In this case, the polyester B constituting the layer B (base layer portion) is not particularly limited, but ethylene terephthalate
Ethylene α, β-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylate, ethylene 2,6-naphthalene
When at least one structural unit selected from the above-mentioned unit etc. is the main constituent component, wear resistance is further improved, and less powder is generated when running on a plastic roll (hereinafter referred to as powder generation). Is desirable. Also,
When the polyester B constituting the present invention is crystalline, mechanical strength, dimensional stability and the like are further improved, which is desirable.

In the case of a biaxially oriented film obtained by laminating the A layer containing polyester A as a main component on at least one surface of the polyester B layer as described above, the abrasion resistance of the film and the generation of powder are further improved. It is desirable because it becomes good. The degree of this orientation is not particularly limited, but wear resistance and powder generation are more favorable when the Young's modulus, which is a measure of the degree of molecular orientation of the polymer, is 350 kg / mm ² or more in both the longitudinal and width directions. Therefore, it is particularly desirable.

When used as a laminated film, the thickness t of the A layer is 0.02 to 3 μm, preferably 0.05 to 2 μm.
m, and more preferably 0.1 to 1 μm. If the thickness t of the A layer is smaller than the above range, the abrasion resistance of the film becomes poor, and conversely if the thickness t is large, powder generation becomes poor, which is not preferable.

The ratio of the surface roughness Ra to Rt of at least one surface of the film of the present invention, Rt / Ra, is required to be 20 or less, preferably 15 or less. Rt
If / Ra is larger than the above range, powder generation becomes poor, which is not preferable.

In the film containing polyester A as a main component, the diameter d of spherulites present in the unstretched film before biaxial stretching is preferably in the range of 0.03 to 0.45 μm. More preferably 0.10 to 0.30 μ
When it is in the range of m, powder generation becomes particularly good, which is desirable.

In the film of the present invention, the average height of the surface protrusions formed on at least one surface is 20 to 800 n.
m, especially in the range of 30 to 600 nm is preferable because the film has particularly good abrasion resistance and powder generation.

[0018] The present invention film is desirably large projections number H1 of at least one surface 200/200 cm ² or less, the abrasion resistance of the film, especially for 100/200 cm ² or less, since dust generation becomes particularly good .

Next, a method for producing the film of the present invention will be described.

Pellets of polyester A, of which the thermoplastic resin having a crystallization parameter ΔTcg of 70 ° C. or less constitutes a part or the whole thereof, are dried and then fed to a known melt extruder and extruded from a slit-shaped die. Cool on a casting roll to make an unstretched film. In the case of a laminated film, the pellets of polyester A and the pellets of polyester B are dried and then supplied to different melt extruders, and polyester A is mixed with polyester using a two- or three-layer manifold or a merge block. B on at least one side of B
Alternatively, a three-layer sheet is extruded. In this case, a method of stacking using a merge block having a rectangular merge cross section is effective for thinly and uniformly depositing a resin that is easily crystallized as in the present invention.

Further, in order to more efficiently obtain a film which meets the object of the present invention, it is a particularly effective means to subject at least one surface of the unstretched film after casting to a heat treatment and then to carry out biaxial stretching. . Here, the unstretched film refers to a state immediately after being extruded from the die and not yet cooled and solidified, to a film slightly stretched (up to about 2 times) in the uniaxial direction. The heat treatment method is not particularly limited, but a method of heat-treating the surface of the casting drum which does not contact the drum with a radiation heater or the like, or a method of heat treatment with a radiation heater or the like between rolls is preferable. The treatment conditions include a temperature of 100 to 250 ° C. and 0.5 to 1
Heat treatment for 50 seconds is desirable.

Next, this unstretched film is biaxially stretched and biaxially oriented. As a stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. However, a sequential biaxial stretching method of first stretching in the longitudinal direction and then in the width direction is used, and the stretching in the longitudinal direction is divided into two or more stages, and the total longitudinal stretching ratio is 3.5 to 5.5 times. The method is also effective for obtaining the surface morphology within the range of the present invention and the spherulite diameter within the desired range without stretching breakage. The temperature in the longitudinal direction, which is 10 to 30 ° C. higher than the glass transition point Tg of polyester A, is effective for obtaining the surface morphology and the desired range of spherulite diameter within the range of the present invention. Longitudinal stretching speed is 5000-5
The range of 0000% / min is preferable.

Stretching in the width direction is also carried out in two stages, which is effective for uniformly stretching a thin and uniform layer of a resin which is easy to crystallize as in the present invention, and has a surface morphology within the scope of the present invention, and is also desirable. It is also effective in obtaining a range of spherulite diameters. A method using a stenter is preferable as the method.
The total draw ratio is in the range of 3.5 times to 5.0 times, which is effective for uniformly drawing a layer in which a resin that is easy to crystallize as in the present invention is thinly and uniformly laminated. It is also effective in obtaining the surface morphology of s and the spherulite diameter in the desired range. The stretching speed in the width direction is 1000 to 20000% /
The range of minutes is preferred.

The stretching temperature in the width direction is the glass transition point T of polyester A (polyester B in the case of a laminated film).
A temperature of 10 to 30 ° C. higher than g is also effective for obtaining the surface morphology and the desired range of spherulite diameter within the range of the present invention.
Alternatively, the biaxially stretched film may be further stretched in at least one direction.

Next, this stretched film is heat-treated. The heat treatment temperature in this case is 20 to 8 from the melting point of polyester A.
A temperature range of 0 ° C. lower and a time range of 0.5 to 60 seconds are also effective for obtaining the surface morphology and the desired range of spherulite diameter within the range of the present invention.

[0026]

According to the polyester film of the present invention, when the crystallinity of the polyester is specified and appropriate production conditions are used, projections are formed on the surface of the film by crystallization without relying on the contained particles. Moreover, the formed protrusions are fine and uniform, and it is presumed that the effect of the present invention was obtained as a result of suppressing the generation of voids.

[0027]

[Physical property measuring method and effect evaluating method] The characteristic value measuring method and effect evaluating method of the present invention are as follows.

(1) Average diameter of spherulites The cross section of the film is observed by an optical or electron microscope, and the measurement is repeated until a total of 100 spherulites can be observed, and the obtained values are averaged to obtain spherulites. The average diameter was used.

(2) Content of Particles A solvent in which the thermoplastic resin is dissolved and the particles are not dissolved is selected, the particles are centrifuged from polyester, and the ratio (% by weight) to the total weight of the particles is taken as the particle content. .
In some cases, the combined use of infrared spectroscopy is also effective.

(3) Crystallization parameter ΔTcg, heat of fusion It was measured using DSC (Differential Scanning Calorimeter) II type manufactured by Perkin-Elmer. The measurement conditions of DSC are as follows. That is, 10 mg of the sample was set in the DSC device, and 3
After melting for 5 minutes at a temperature of 00 ° C., it is quenched in liquid nitrogen. The temperature of this quenched sample is raised at 10 ° C./min, and the glass transition point Tg is detected. The temperature was further raised, and the crystallization exothermic peak temperature from the glass state was set as the cold crystallization temperature Tcc. The temperature was further raised and the heat of fusion was determined from the melting peak. Here, the difference between Tcc and Tg (Tcc-Tg) is defined as the crystallization parameter ΔTcg.

(4) Average Height of Surface Protrusion 2 Detector type scanning electron microscope [ESM-3200,
Elionix Co., Ltd.] and cross-section measuring device [PMS-1,
Elionix Co., Ltd.], the height of the flat surface of the film surface is measured as 0, and the measured height of the projection is measured by an image processing apparatus [IBAS2000, Carl Zeiss Co., Ltd.].
Manufactured] to reconstruct the film surface projection image on the image processing device. Next, the equivalent circle diameter is calculated from the area of each protrusion obtained by binarizing the protrusion portion in this surface protrusion image, and this is made the average diameter of the protrusion. In addition, the highest value among the binarized individual projection portions is set as the height of the projection, and this is obtained for each projection. This measurement was repeated 500 times at different places to determine the number of protrusions, and the average value of the heights of all the measured protrusions was taken as the average height. In addition, the standard deviation of the height distribution was calculated based on the height data of each protrusion. The magnification of the scanning electron microscope is 1000
Select a value between ~ 8000 times. In some cases, the height information obtained using a high-precision optical interference type three-dimensional surface analyzer (TOPO-3D manufactured by WYKO, objective lens: 40 to 200 times, use of a high resolution camera is effective) is used for the SEM. You may read and use it for the value of.

(5) Centerline average surface roughness Ra and maximum height Rt Measurement was performed using a high precision thin film step measuring instrument ET-10 manufactured by Kosaka Laboratory. The conditions are as follows, and the average value of 20 measurements was used as the value.・ Stylus tip radius: 0.5 μm ・ Stylus load: 5 mg ・ Measurement length: 1 mm ・ Cutoff value: 0.08 mm Ra and Rt are defined, for example, by Jiro Nara, “Measurement / Evaluation of Surface Roughness”. Law "(General Technology Center, 198
3).

(6) Young's modulus According to the method defined in JIS-Z-1702,
25 using an Instron type tensile tester
It was measured at 65 ° C. and 65% RH.

(7) Layer A Layer Thickness The layer thickness may be determined by utilizing the difference between polyester A and polyester B by ATR-IR (total reflection infrared spectroscopy) or the like. Alternatively, the layer thickness can be obtained by recognizing the interface by observing the cross section with an electron microscope or the like.

(8) Number of coarse surface protrusions H1 ^Two measurement surfaces (100 cm ² ) are superposed and brought into close contact with each other by electrostatic force (printing voltage 5.4 kV). The height of the coarse protrusions was determined from the Newton ring generated by the interference of light at the coarse protrusion portion between the two films, and the number of coarse protrusions of a single ring or more was defined as H1. The unit of H1 is the number of pieces / 200 cm ² because two pieces of 100 cm ² are stacked. The light source used was a halogen lamp with a 564 nm bandpass filter.

(9) Abrasion resistance The film was slit into a tape having a width of 1/2 inch, and a tape running tester (TBT30 manufactured by Yokohama System) was used.
0D / H) to run on a guide pin (surface roughness: Rt 1 μm). (Running speed 2000m / min,
10 passes, winding angle: 60 degrees, running tension: 9
0 g). At this time, the scratches in the film were observed with a microscope, and it was judged that scratches with a width of 2.5 μm or more were excellent when less than 2 per tape width, good when 2 or more and less than 5 were good, and bad when 5 or more. Good is desirable, but good is practically usable.

(10) Generation of powder during running of plastic rolls Similar to the above-mentioned evaluation of abrasion resistance, except that the guide pins were made of polyoxymethylene (surface roughness: 1 μm in Rt), and then run. The amount of powder generated on the pin was observed. Excellent when no powder was found at all, good when the area of the adhered powder was less than 1/10 of the apparent contact area between the pin and the film, 1/10 In the above cases, it was determined to be defective. Good is desirable, but good is practically usable.

[0038]

EXAMPLES The present invention will be described based on examples.

Examples 1 to 3 Chips of some kinds of polyesters (polyester A) having different crystallinity parameters shown in Table 1 were dried under reduced pressure (3 Torr) at 180 ° C. for 3 hours and fed to an extruder at 290 ° C.
Melt-extrusion was carried out, and the film was wound around a casting drum having a refrigerant temperature of 15 ° C. by an electrostatically applied cast method and cooled and solidified to form an unstretched film. This unstretched film was stretched at a temperature of 80 ° C. in the longitudinal direction by a ratio of 1.5 times in the first step and 3 times in the second step, for a total of 4.5 times. This uniaxially stretched film was stretched twice in the width direction at 100 ° C. at a stretching rate of 2000% / min using a stenter, and then at 110 ° C. twice. Next, heat-treat at 200 ° C for 5 seconds under a fixed length,
A biaxially oriented polyester film having a total thickness of 15 μm was obtained. The parameters of the present invention of these films are as shown in Table 1. When the parameters of the present invention are within the range, the film is excellent in both abrasion resistance and powder generation during running of plastic rolls. I understood.

Examples 4 and 5 Using PET having the crystallinity parameters shown in Table 1 and a catalyst composition as described below, the unstretched film after casting, which is not in contact with the casting drum, is as follows. After the heat treatment under the conditions, the same stretching process as in Examples 1 to 3 was performed to obtain a biaxially oriented film.

Example 4: Antimony trioxide 0.03 wt% Magnesium acetate 0.10 wt% Dimethylphenylphosphonate 0.20 wt% Heat treatment condition 170 ° C. for 10 seconds Example 5: Catalyst composition similar to Example 4 Heat treatment condition 190 ° C. 6 Second Comparative Example 1 Using PET having the catalyst composition as described below, Examples 1 to 1
A biaxially oriented film was obtained by the same process as in 3.

Antimony trioxide 0.03 wt% Magnesium acetate 0.08 wt% Trimethyl phosphate 0.15 wt% Heat treatment condition 160 ° C. for 15 seconds Comparative Example 2 In the PET used in Comparative Example 1, calcium carbonate having an average particle size of 0.6 μm Using a pellet containing 0.7 wt% of particles, a biaxially oriented film was obtained in the same process as in Examples 1 to 3.

[0043]

[Table 1]

[0044]

EFFECTS OF THE INVENTION According to the polyester film of the present invention, by making the crystallinity of the polyester specific, projections are formed on the surface of the film by crystallization, and abrasion resistance and plastic roll running The effect of suppressing the generation of powder can be achieved at the same time.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // B29K 67:00 B29L 7:00 4F C08L 67:02

Claims (5)

[Claims] 1. A biaxially oriented film containing polyester A as a main component, wherein a part or all of the polyester A is made of a thermoplastic resin having a crystallinity parameter ΔTcg of 70 ° C. or less. A polyester film having a ratio of surface roughness Ra and Rt of at least one surface of Rt / Ra of 20 or less. 2. The polyester film according to claim 1, wherein the ratio of the surface roughness Ra to Rt of at least one surface, Rt / Ra, is 15 or less. 3. The diameter d of the spherulites present in the unstretched film of the biaxially oriented film before biaxial stretching is 0.03 to.
The polyester film according to claim 1, which has a thickness of 0.45 μm. 4. A polyester film comprising the polyester B as a main component, and the polyester film according to claim 1 laminated on at least one surface of the film. 5. The thickness t of the polyester A layer is 0.02.
It is 3 micrometers, The polyester film of Claim 4 characterized by the above-mentioned.