JP2513727B2 - Biaxially oriented polyester film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a biaxially oriented polyester film.

[Prior Art] As a biaxially oriented polyester film, a film in which inert inorganic particles are contained in polyester is known (for example, JP-A-61-261347).

[Problems to be Solved by the Invention] With the recent increase in the process speed of a film processing process (for example, a printing process), powder whose surface is scraped by a roll (rubber roll) contacting the film in the process is generated. The rolls are easily attached to the rolls and become dirty. Therefore, the rolls are regularly cleaned. However, the conventional biaxially oriented polyester film described above has a problem that it is difficult to remove stains adhering to the roll and hinders productivity.

The present invention is to improve such problems, while maintaining the slipperiness of the film required for any application, it is easy to remove the dirt attached to the roll in the processing step, yet to provide a film that does not easily damage the roll To do.

[Means for Solving Problems] A film containing a composition of polyester, internally precipitated particles, and / or inert particles as a main component, wherein the weight of the polyester in the scrapes on at least one side of the film A biaxially oriented polyester film having a ratio of 0.5 to 0.95 and a surface average roughness of 3 to 30 nm.

The polyester in the present invention is ethylene terephthalate, ethylene α, β-bis (2-chlorophenoxy)
At least one structural unit selected from ethane-4,4'-dicarboxylate and ethylene 2,6-naphthalate units is a main constituent. However, other components may be copolymerized within a range not hindering the present invention, preferably within 15 mol%.

The inert particles in the present invention are not particularly limited, but the crystallization acceleration coefficient dΔTcg is 5 to 25 ° C., preferably 7 to 20.
C. is effective for obtaining a scraped material composition ratio within the range of the present invention, and substantially spherical silica derived from colloidal silica, synthetic calcium carbonate, .alpha.-alumina, rutile titanium dioxide, and particularly spherical silica. desirable. In the case of colloidal silica, a known method such as an ion exchange method or an alkoxide method can be used as a manufacturing method. The average particle size of the inert particles is not particularly limited, 0.08 ~ 1.5μ
When it is in the range of m, it is effective to obtain the scraped material composition ratio in the range of the present invention.

The internal precipitation particles in the present invention, calcium compound added during polyester polymerization, magnesium compound,
The particles are formed by combining at least one lithium compound and a polyester component. The internally precipitated particles of the present invention may contain elemental phosphorus and a trace amount of other metal components, such as zinc, cobalt, antimony, germanium, and titanium, within a range that does not impair the object of the present invention. Good.

The film of the present invention contains the above composition as a main component, but may be blended with other polymers within a range that does not impair the object of the present invention, and may further contain an antioxidant, a heat stabilizer, a lubricant, an ultraviolet absorber. Inorganic or organic additives such as nucleating agents may be added to the extent that they are usually added.

The film of the present invention is a film in which the above composition is biaxially oriented. Unstretched or uniaxially stretched film is not preferable because it is difficult to remove the deposits on the roll. The refractive index ratio in the thickness direction showing the degree of the orientation is not particularly limited,
The range of 0.935 to 0.975, preferably 0.940 to 0.970 is particularly preferred.

The film of the present invention has a weight ratio of polyester in the scraped product of at least one surface of 0.5 to 0.95, preferably 0.6 to 0.95.
It should be 0.90. If the weight ratio of the polyester in the scraped product is smaller than the above range on both sides of the film, the roll is easily scratched, which is not preferable. On the other hand, when it is larger than the above range, it is difficult to remove the deposits on the roll, which is not preferable. Also, both sides are 0.5 to 0.9
5, preferably from 0.6 to 0.90 is particularly desirable in terms of easy removal of dirt and scratch resistance of the roll.

The film of the present invention has a surface average roughness Ra of at least one surface.
Should be 3 to 30 nm, preferably 6 to 25 nm. If the surface average roughness Ra is less than the above range on both sides of the film, it is difficult to remove the deposits on the roll, which is not preferable. On the other hand, if it exceeds the above range, the roll is likely to be damaged, which is not preferable.

When the film of the present invention contains inert particles, the ratio of the crystallization acceleration coefficient dΔTcg (° C.) to the surface average roughness Ra (nm) of at least one surface, dΔTcg / Ra is 0.5 to 2.
A value of 0, particularly in the range of 0.6 to 1.7, is desirable because it makes it easier to remove the deposits on the roll.

The film of the present invention has an effective space volume of at least one surface protrusion of 2 × 10 ³ to 1 × 10 ⁵ , preferably 1 × 10 ^4.
When it is in the range of from 1 × 10 ⁵ , the slipperiness and the ease with which the deposits on the roll can be removed are further improved, which is particularly desirable.

The film of the present invention has a refractive index of 1.655 to 1.700 in the width direction,
Particularly in the range of 1.675 to 1.700, the ease with which the deposits on the roll can be removed is further improved, which is particularly desirable.

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

First, as a method of containing inert particles in a predetermined polyester, it may be added before the polymerization, during the polymerization, or after the polymerization, but mixed with ethylene glycol, which is the diol component of the polyester, in the form of a slurry, The method of dispersing and adding is effective in satisfying the composition ratio of the scraped product of the present invention. Further, as a method for controlling the content of particles, a high concentration, preferably a particle concentration of 1 to 5% by weight
The method of diluting the master pellet of 1) at the time of film formation is effective for obtaining the composition ratio of the scraped product of the present invention. In addition, ethylene glycol slurry is 140 ~ 200 ℃, especially 180 ~ 200 ℃
For 30 minutes to 5 hours, especially 1 to 3 hours, or to add 0.5 to 20% by weight of ammonium phosphate salt based on the amount of particles, the composition ratio of the scraped product of the present invention is obtained. It is extremely effective for Also, a high concentration, preferably 1 to 5 wt% of the melt viscosity of the master pellet,
By adjusting the copolymerization components, the glass transition temperature Tg and cold crystallization temperature
The difference from Tcc, ΔTcg (= Tcc-Tg), is 65-110 ℃, especially 70-
Keeping at 100 ° C. is effective for obtaining the composition ratio of the scraped product of the present invention. In this case, an isophthalic acid component and a cyclohexane dimethine glycol component are suitable as the copolymerization component.

The following method is effective as a method for generating the internally deposited particles. That is, (1) a process of polycondensation through direct esterification of a predetermined dicarboxylic acid and ethylene glycol, or (2) a polycondensation through a transesterification reaction of dimethyl ester of a predetermined dicarboxylic acid with ethylene glycol. In the process, it is produced by adding at least one of a calcium compound, a magnesium compound, a manganese compound and a lithium compound soluble in glycol, and preferably an acid and / or ester compound of phosphorus. Examples of calcium, magnesium, manganese, and lithium compounds that can be used here include inorganic acid salts such as halides, nitrates, and sulfates, organic acid salts such as acetates, oxalates, and benzoates, hydrides, and oxides. Most preferred are glycol-soluble compounds such as compounds, but two or more kinds may be used in combination. As the phosphide, one or more of phosphate, phosphorous acid, phosphonic acid and their esters and partial esters are used.

Thus, after sufficiently drying the pellets containing the inert particles and / or internally precipitated particles, the pellets are fed to a known melt extruder, extruded into a sheet form from a slit die at 270 to 330 ° C., and cooled on a casting roll. An unstretched film is made by solidifying. In this case, the composition ratio of the scraped product within the scope of the present invention is to set the ratio of the die slit gap / the thickness of the unstretched film to 5 to 30, preferably 8 to 20 when extruded into an unstretched film. Is effective in obtaining.

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, first use the sequential biaxial stretching method of stretching in the longitudinal direction, then in the width direction,
The elongation in the longitudinal direction is from (glass transition point of polymer -10 ° C)
A method in which the glass transition point of the polymer is + 10 ° C. is preferable in order to obtain the composition ratio of the scraped material within the range of the present invention. As a stretching method in the width direction, a method using a stenter is generally used. The draw ratio is 3.0-
A range of 5.0 times is appropriate. Stretching speed in the width direction is 1000
The range of up to 20000% / min is preferred. Next, this stretched film is heat-treated. The heat treatment temperature in this case is 170-220
The range of 0.5 to 60 seconds is suitable for the temperature and time. Further, it is effective to draw 1.05 to 1.3 times, particularly 1.05 to 1.2 times in the width direction during the heat treatment in order to obtain the composition ratio of the scraped product within the scope of the present invention.

[Function] In the present invention, the composition ratio of the scraped material of the film and the surface average roughness are set in the specific ranges, so that the adhesiveness to the roll can be reduced, and it is presumed that the deposited material on the roll is easily removed. To be done.

[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) Surface average roughness Ra Stylus type surface roughness meter (Kosaka Laboratory ET-10, stylus diameter 0.5μ
m) was used and measured according to JIS-B-0601. However, the cutoff was 0.08 mm and the measurement length was 1 mm.

(2) Average particle size of particles Polyester is removed from the film by plasma ashing method or o-chlorophenol dissolution method, dispersed in ethanol, and volume average measured by centrifugal sedimentation method (Horiba Seisakusho, CAPA500 used) Is the diameter.

(3) Content of particles After adding 1.0 liter of o-chlorophenol to 100 g of polyester and heating at 120 ° C. for 3 hours, ultracentrifuge 55P-72 manufactured by Hitachi Koki Co., Ltd. was used and centrifuged at 30,000 rpm for 40 minutes. Then, the obtained particles are vacuum dried at 100 ° C. When a fine particle corresponding to a polymer is observed when the fine particles are measured with a scanning differential calorimeter, o-chlorophenol is added to the fine particles, and after heating and cooling, centrifugation is performed again. When the dissolution peak is no longer observed, the fine particles are designated as precipitated particles. Usually, two centrifugation operations are sufficient. The ratio (% by weight) to the total weight of the particles thus separated is β.

(4) Glass transition point Tg, cold crystallization temperature Tcc It was measured using DSC (Differential Scanning Calorimeter) Model II manufactured by Perkin Elmer. The DSC measurement conditions are as follows.
That is, 10 mg of a sample is set in a DSC apparatus, melted at a temperature of 300 ° C. for 5 minutes, and then rapidly cooled 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. Here, the difference between Tcc and Tg (Tcc−Tg) is defined as ΔTcg.

(5) Crystallization acceleration coefficient dΔTcg (unit: ° C) ΔTcg (I) of the polyester containing 1% by weight of the inactive particles and ΔTcg (II) of the polyester of the same viscosity obtained by removing the inactive particles from the above method Measure and ΔTcg
Difference between (II) and ΔTcg (I) [ΔTcg (II) -ΔTcg (I)
Was used as the crystallization acceleration coefficient dΔTcg.

(6) Effective space volume of protrusion Using Kosaka Laboratory's high-precision thin film step measuring device ET-10, stylus tip radius 0.5 μm, cutoff 0.08 mm, measurement length 1.0 mm,
The surface roughness curve of the film is measured at a longitudinal magnification of 200,000 times and a lateral magnification of 2000 times. A peak count level is provided every 0.005 μm in parallel above the average line (center line) of this roughness curve, and the point where the above-mentioned peak count level is crossed at least once between two points where the curve intersects the average line. When there is, this is regarded as one peak, and the number of this peak is determined during the measurement length. For each peak count level, the number of peaks is determined, and the number of peaks determined for the n-th peak count level from the average line is defined as PC (n). When the peak count level at which the number of peaks starts to become zero during the measurement length is mth from the average line, the effective space volume Φ
Is The average value of 50 measurements taken at different locations is used.

(7) Refractive index The sodium D line (589 nm) was used as a light source, and the refractive index was measured using an Abbe refractometer. Methylene iodide was used as the mount solution, and measurement was performed at 25 ° C. and 65% RH.

(8) Polyester ratio of scraped material A film is slit into a tape shape with a width of 1/2 inch, a single blade is pressed vertically, and the product is run for 20 cm while being pushed 0.5 mm (running tension: 500 g, running speed: 6.7). cm/
Seconds). At this time, the shavings of the film surface attached to the tip of the single-edged blade are subjected to compositional analysis by the microscopic FT-IR method (Fourier transform microscopic infrared spectroscopy), and the peaks due to the carbonyl group of the polyester and the peaks due to the inorganic substances contained It was calculated from the ratio. In order to convert the peak height ratio into a weight ratio, a calibration curve was prepared in advance using a sample with a known weight ratio, and the polyester ratio with respect to the total amount of polyester and inorganic substances was determined. An X-ray microanalyzer was also used as needed.

(9) Sliding property (friction coefficient with metal guide) Using tape running tester TBT-300 type (manufactured by Yokohama System Research Co., Ltd.), run in 20 ° C, 60% RH atmosphere,
The initial μK (coefficient of friction) was determined by the following formula (the film width was 1/2 inch).

μK = 0.733log (T ₂ / T ₁ ) where T ₁ is the inlet tension and T ₂ is the outlet tension. The guide diameter is 6mmφ, the guide material is SUS27 (surface viscosity 0.2S),
The wrap angle is 180 ° and the running speed is 3.3 cm / sec.

When the above-mentioned μK of at least one surface of the film was 0.25 or less, the slipperiness was good, and when it was more than 0.25, the slipperiness was poor. The μK value of 0.25 is a critical point of whether or not troubles due to slippage will occur in processing steps such as printing steps.

(10) Ease of removing adhered material from rolls The nylon guide was used instead of the metal guide of the tape running tester TBT-300 type (manufactured by Yokohama System Laboratory Co., Ltd.), and the running speed was 1 m / sec. It was run so that the length would be 50,000m. At this time, the ease with which dirt adhered to the nylon roll was removed was examined. It was judged to be easy to remove when wiped off easily with a cloth: ○, and easy to remove even if a solvent such as acetone was not used: X.

(11) Durability of roll damage After running the film under the above conditions, the nylon roll was visually observed to check for scratches. When the roll was not scratched at all, it was difficult to scratch the roll: good (∘), and when even one roll was scratched, it was judged as poor (x).

[Examples] The present invention will be described based on examples.

Examples 1 to 5 and Comparative Examples 1 to 4 Ethylene glycol slurries containing 1% by weight of several kinds of inorganic particles having different average particle diameters were prepared. These ethylene glycol slurries and dimethyl terephthalate were transesterified and then polycondensed to prepare polyethylene terephthalate particle master pellets containing 1% by weight of particles. The degree of polymerization of these master pellets and the ratio of the copolymerization components were adjusted to prepare particle master pellets as shown in Table 1. These particle master pellets and polyethylene terephthalate pellets containing substantially no particles were mixed so that the content of the particles was a predetermined amount, and the pellets were dried under reduced pressure at 180 ° C. for 3 hours (3
Torr). Feed the mixed pellets to the extruder and
Melt extruded at ℃, change the ratio of die slit gap / thickness of unstretched film, wrap around a casting drum with a surface temperature of 30 ℃ using an electrostatically applied cast method, and solidify by cooling. A 180 μm unstretched film was made.
This unstretched film was stretched 3.4 times in the longitudinal direction at 80 ° C. This drawing was carried out at a peripheral speed difference between the two sets of rolls, and the drawing speed was 8000% / min. This uniaxially stretched film was stretched 3.6 times in the width direction using a stenter. At this time, the temperature was 100 ° C. and the speed was 3000% / min. Furthermore, while stretching 1.2 times in the width direction, heat treatment at 200 ° C for 5 seconds
A 15 μm biaxially oriented film was obtained. The composition ratio and surface average roughness of the scraped products of these films are as shown in Table 1. When the above parameters are within the range of the present invention, the slipperiness and the film on which dirt easily attached to the roll is easily removed. Although it is obtained and the roll is not easily scratched, it can be seen that when the parameter is out of the range of the present invention, a film having slipperiness, easy removal of dirt, and scratch resistance of the roll cannot be obtained. All the films had the same parameters of the present invention on the front and back surfaces of the film.

[Effects of the Invention] In the present invention, since the composition ratio and surface roughness of the scraped material are within the specific ranges, it is easy to remove the dirt adhered to the roll in the processing step while maintaining the required slipperiness, and it is difficult to damage the roll. The polyester film is obtained, and can cope with an increase in processing speed in the printing process and the like. The use of the film of the present invention is not particularly limited, but it is suitable for packaging, graphics, etc., and of course, it is also useful for a magnetic recording medium passing through a calendar process.

Claims (1)

(57) [Claims] 1. A film comprising a composition comprising polyester and internally precipitated particles and / or inert particles as a main component, wherein the weight ratio of polyester in the scraped material on at least one side of the film is 0.5 to 0.95. And a surface average roughness of 3 to 30 nm, a biaxially oriented polyester film.