JPH11228677A - Polyethylene terephthalate and film therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyethylene terephthalate capable of forming fine projections without using externally added particles, and useful for a formed product such as a film excellent in abrasion resistance. SOLUTION: This polyethylene terephthalate has a melting peak at >=290 deg.C, and is obtained, for example, by polymerizing ethylene glycol and dimethyl terephthalate to provide a polymer having <=0.65 (preferably <=0.63) IV, and drying the obtained polymer in vacuum by separating the stage to three or more steps (preferably five steps) under the conditions at 110-130 deg.C for 2-3 hr, at 140-160 deg.C for 2-4 hr, at 170-200 deg.C for 2-6 hr, at 210-220 deg.C for 2-8 hr, and at 225-235 deg.C for 2-6 hr while gradually raising the temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to polyethylene terephthalate, a polyethylene terephthalate composition and a film comprising the same.

[0002]

2. Description of the Related Art As a prior art concerning a polyester film, there is, for example, Japanese Patent Publication No. 7-54576.

[0003]

However, the melting point of the above-mentioned conventional polyethylene terephthalate is usually 260 ° C.
And no melting peak at 290 ° C. or higher was known. The present invention relates to polyethylene terephthalate having a melting peak at 290 ° C. or higher, and a polyethylene terephthalate composition containing this special polyethylene terephthalate has a proportion that does not melt at a normal extrusion temperature (melting point). The present invention provides a polyethylene terephthalate and a film comprising the same, which, when formed into a film, form projections without adding external particles to the film surface.

[0004]

[Means for Solving the Problems]

The above-mentioned object of the present invention is achieved by a polyethylene terephthalate having a melting peak at 290 ° C. or higher, a polyethylene terephthalate composition containing the polyethylene terephthalate, and a film made of the composition.

BEST MODE FOR CARRYING OUT THE INVENTION The polymer of the present invention is polyethylene terephthalate having a melting peak above 290 ° C., and the polyethylene terephthalate composition of the present invention consists essentially of polyethylene terephthalate.
It has a melting peak at 90 ° C. or higher. However, as long as the object of the present invention is not impaired, two or more kinds of polymers may be mixed or a copolymerized polymer may be used. In addition, additives such as an antioxidant, a heat stabilizer, and an ultraviolet absorber may be added to the extent that the objects of the present invention are not impaired.

[0006] The polyethylene terephthalate of the present invention is 2
It has a melting peak above 90 ° C. The melting peak appears as an endothermic peak in differential scanning calorimetry (DSC), and the position of the peak is not particularly limited as long as it is 290 ° C. or higher, but the upper limit is about 340 ° C. due to thermal decomposition.

The polyethylene terephthalate of the present invention comprises
By adding to conventionally known polyethylene terephthalate, fine projections are formed, so that the composition becomes a preferable composition for forming a molded product such as a film. When the polyethylene terephthalate composition obtained is used for producing the polyethylene terephthalate of the present invention, it is not necessary to isolate the heat-resistant polyethylene terephthalate of the present invention. Whether or not the polyester composition of the present invention contains the above-mentioned heat-resistant polyethylene terephthalate is determined by whether or not the composition or the molded article has a melting peak of 290 ° C. or more.

[0008] The polyethylene terephthalate composition of the present invention may further contain particles. In that case, the average particle size is not particularly limited, but is 0.05 to 1.0.
μm, preferably 0.1 to 0.8 μm, and the content is not particularly limited, but is 0.05 to 1.0% by weight. Preferred examples of such particles include particles selected from calcium carbonate, alumina, silica, aluminum silicate, calcium phosphate, organic particles, and the like. A plurality of these particles may be used in combination.

The film made of the polyethylene terephthalate composition of the present invention may be a single-layer film or a laminated film. In the case of a laminated film, 29
The thickness of the laminated portion composed of the polyethylene terephthalate composition having a melting peak at 0 ° C. or higher is not particularly limited, but is preferably 0.01 to 3.0 μm, more preferably 0.05 to 2.0 μm, and still more preferably, from the viewpoint of projection formation. 0.1 ~
1.5 μm.

The use of the biaxially oriented polyester film of the present invention is not particularly limited, such as for magnetic recording media, packaging, and cards such as prepaid cards. It can also be preferably used for data storage for digital video tapes, computers, etc., which require high output.

Next, a preferred method for producing the polyethylene terephthalate, the polyethylene terephthalate composition and the film comprising the same according to the present invention will be shown and described, but the present invention is not limited thereto.

First, as a polymerization method of polyethylene terephthalate, polyethylene terephthalate is obtained from dimethyl terephthalate and ethylene glycol by using a normal transesterification catalyst such as magnesium acetate and lithium acetate and a normal polymerization catalyst such as antimony trioxide. . Also,
As a method for containing particles in polyethylene terephthalate, it is preferable to disperse the particles in ethylene glycol, which is a diol component, in the form of a slurry, and polymerize the ethylene glycol with dimethyl terephthalate. At that time, in order to obtain the polyethylene terephthalate having a melting peak at 290 ° C. or higher of the present invention, for example, the final polymer IV is 0.65 or lower, preferably 0.63 or lower.

Next, the polyethylene terephthalate obtained by the above polymerization is dried in a vacuum. At that time, in order to obtain polyethylene terephthalate having a melting peak at 290 ° C. or higher of the present invention, for example, the drying conditions are divided into three or more stages, preferably five or more stages, and at 110 to 130 ° C. for two to three hours, 140 to 170 ~ 2 hours at 160 ° C
A preferred example is a method of gradually increasing the temperature at 200 ° C for 2 to 6 hours, 210 to 220 ° C for 2 to 8 hours, and 225 to 235 ° C for 2 to 6 hours.

The mixture is fed to a known melt extruder and used in the present invention.
In order to obtain polyethylene terephthalate having a melting peak at 0 ° C. or higher, it is melted at, for example, 250 to 275 ° C., extruded in a sheet form from a slit die, and cooled and solidified at 10 to 40 ° C. on a castin roll. To make an unstretched film. If necessary, a plurality of extruders, a plurality of manifolds or a merging block are used to laminate the polyester in a molten state.

Next, the unstretched film is biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be used. First, using the sequential biaxial stretching method of stretching in the longitudinal direction and then in the width direction,
The longitudinal stretching is divided into three or more stages, and the longitudinal stretching temperature is 80
It is preferably exemplified that the stretching is performed at a temperature of from 130 to 130 ° C., a total longitudinal stretching ratio of 3.0 to 5.0 times, and a longitudinal stretching speed of 5,000 to 50,000% / min. As a stretching method in the width direction, a method using a tenter is preferable, a stretching temperature is 80 to 150 ° C., and a stretching ratio in the width direction is 3.0 to 5.0 times, which is larger than the longitudinal magnification in some cases.
The stretching is preferably performed at a stretching speed in the width direction of 1,000 to 20,000% / min. Further, if necessary, re-longitudinal stretching and re-lateral stretching are performed.

Next, the biaxially oriented film is heat-treated.
The heat treatment temperature in this case is 170 to 220 ° C., especially 170
The time at -210 ° C is preferably in the range of 0.5-60 seconds.

[Method for Measuring Physical Properties and Method for Evaluating Effect] The method for measuring characteristic values and the method for evaluating effect according to the present invention are as follows.

(1) Melting peak of polymer A sample mass of 5 mg was measured using a differential scanning calorimeter (DSC).
The measurement was performed at a heating rate of 120 K / min and a measurement temperature range of 0 to 350 ° C. The melting peak is not noise caused by the measurement and is recognized as a peak. For example, the peak area is 10 J / mo.
More than l was defined as the melting peak.

(2) Film Lamination Thickness The depth distribution of the particle concentration is measured by a secondary ion mass spectrometer, X-ray photoelectron spectroscopy, infrared spectroscopy, or a confocal microscope. After obtaining a maximum value in the depth direction with respect to the surface, a depth that is の of the maximum value was defined as a lamination thickness. In addition, it can be determined not only from the depth distribution of the particle concentration but also from observation of the cross section of the film or a thin film level difference measuring instrument.

(3) Abrasion resistance A film obtained by slitting a film to a width of 1/2 inch was guided by a tape running tester using a guide pin (surface roughness Ra10).
0 nm) (running speed 300 m / min, running frequency 1 time, winding angle 60 °, running tension 60 g). At this time, the wound in the film was observed with a microscope, and the width was 2.5 μm.
Less than 3 scratches per tape width are good, and less than 3-10 scratches per tape width are not good, but 10 or more scratches that can withstand use are judged to be bad.

[0021]

Next, embodiments of the present invention will be described based on examples.

Example 1 Polyethylene terephthalate was polymerized from dimethyl terephthalate and ethylene glycol using magnesium acetate and lithium acetate as transesterification catalysts and antimony trioxide as a polymerization catalyst. At this time, the final polymer IV is 0.1.
61.

Next, the polyethylene terephthalate obtained above was dried under reduced pressure (1 Torr). At that time, the drying conditions were divided into five or more stages, 120 ° C. for 2 hours, 150 ° C. for 3 hours,
The temperature was gradually increased at 180 ° C for 5 hours, 210 ° C for 6 hours, and 230 ° C for 3 hours.

This polymer was fed to a twin screw extruder (Polymer A). Polyethylene terephthalate obtained by a usual method containing 0.1% by weight of calcium carbonate particles having an average particle size of 0.8 μm was dried at 180 ° C. for 6 hours, and then supplied to an extruder (Polymer B). These were melted at 256 ° C. and 280 ° C., respectively, and filtered, and then two layers were laminated using a rectangular junction (A / B). Next, the film was wound around a casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method and cooled and solidified to form an unstretched film. The discharge amount of each extruder was adjusted to adjust the total thickness and the thickness of the polymer A layer.

This unstretched film was stretched 3.5 times in the longitudinal direction at a temperature of 95 ° C. This stretching was performed in three stages with a difference in peripheral speed between two sets of rolls. This uniaxially stretched film was stretched 3.6 times in the width direction at 100 ° C. using a tenter. This film was heat-treated at 200 ° C. for 3 seconds under a fixed length to obtain a biaxially oriented film having a total thickness of 11 μm and a polymer A layer thickness of 1.0 μm.

The properties of this biaxially oriented polyester film show a melting peak at 290 ° C. or higher, and projections originating from polyethylene terephthalate due to so-called foreign matters remaining without being melted during melt extrusion are formed on the film surface. The wear resistance was good.

Comparative Example 1 Polyethylene terephthalate was polymerized from dimethyl terephthalate and ethylene glycol using magnesium acetate and lithium acetate as transesterification catalysts and antimony trioxide as a polymerization catalyst. At this time, the final polymer IV is 0.1.
66.

Next, the polyethylene terephthalate obtained above was dried under reduced pressure (1 Torr). At that time, the drying condition was 180 ° C. for 6 hours.

The polymer was fed to a conventional single screw extruder (Polymer A). Polyethylene terephthalate obtained by a usual method containing 0.1% by weight of calcium carbonate particles having an average particle size of 0.8 μm was dried at 180 ° C. for 6 hours, and then supplied to an extruder (Polymer B). These were melted at 280 ° C. and 280 ° C., respectively, filtered, and then two layers were laminated using a rectangular junction (A / B). Then
The film was wound around a casting drum having a surface temperature of 25 ° C. using an electrostatic application casting method, cooled and solidified to form an unstretched film. The discharge amount of each extruder was adjusted to adjust the total thickness and the thickness of the polymer A layer.

This unstretched film was stretched 3.5 times in the longitudinal direction at a temperature of 95 ° C. This stretching was performed in three stages with a difference in peripheral speed between two sets of rolls. This uniaxially stretched film was stretched 3.6 times in the width direction at 100 ° C. using a tenter. This film was heat-treated at 200 ° C. for 3 seconds under a fixed length to obtain a biaxially oriented film having a total thickness of 11 μm and a polymer A layer thickness of 1.0 μm.

The properties of this biaxially oriented polyester film did not show a melting peak at 290 ° C. or higher, and no projections caused by polyethylene terephthalate due to so-called foreign matters remaining without being melted during the melt extrusion were formed on the film surface.

The biaxially oriented polyester film of the present invention had good abrasion resistance, but the other film did not have good abrasion resistance.

[0033]

As described above, the polyethylene terephthalate composition containing polyethylene terephthalate of the present invention and the film comprising the same have polyethylene terephthalate which remains without being melted at the time of melt extrusion. However, since the projections do not depend on the externally added particles, the abrasion resistance is excellent.

Claims (3)

[Claims] 1. A polyethylene terephthalate having a melting peak at 290 ° C. or higher. 2. A polyethylene terephthalate composition comprising the polyethylene terephthalate according to claim 1. 3. A polyethylene terephthalate film comprising the polyethylene terephthalate composition according to claim 2.