KR100243944B1 - Method of producing polyester film having multilayer - Google Patents

Abstract

[Technical field to which the invention described in the claims belong]

The present invention relates to a method for producing a polyester film having a multilayer structure of three or more layers.

[Technical problem to be solved]

The present invention is coextruded to a predetermined thickness by using a reclaimed chip to lower the roughness of one side of the film to reduce the drop out (Drop Out) in the manufacture of magnetic tape, while having good electronic properties, and the other ( That is, the roughness of the running surface) is to provide a method for producing a polyester film that does not cause scratches by adjusting the outer layer thickness to have good slidability and wear characteristics.

[Summary of the solution of the invention]

According to the present invention for solving the above problems, "the sheet before stretching has a structure of at least three layers or more, and the critical viscosity of the intermediate layer polymer is 0.5 mW / g to 0.6 mW / g and the average particle diameter is 0.4 µm to 2.0 µm. A reclaimed chip containing 1% by weight to 3% by weight of phosphorus particles to have an average roughness of 30 nm or more, and the outermost polymer having the same polymer as that of the intermediate layer with a viscosity of 0.6 ㎗ / g to 0.7 ㎗ / g and 0.01 to 3% by weight of particles having an average particle diameter of 0.001 µm to 1 µm, and can be achieved by designing such that the average roughness in a single layer is 13 nm or less.

[Important Uses of the Invention]

This invention has the use as the manufacturing method of the film which has the outstanding electronic characteristic.

Description

Method for producing a polyester film having a multilayer structure

The present invention relates to a method of manufacturing a polyester film having a multilayer structure, and more particularly, has a multilayer structure produced by co-extrusion, and good electronic properties while reducing the drop out when manufacturing magnetic tape The present invention relates to a method for producing a polyester film having an excellent scratch resistance and abrasion resistance.

Saturated linear polyester film represented by polyethylene terephthalate has excellent mechanical properties, heat resistance, weather resistance, electrical insulation, chemical resistance, etc., and is used in a wide range of fields such as packaging, photography, electricity, and magnetic tape.

In particular, the polyester film used for porcelain is required to be processed by coating or the like method to impart such characteristics because high electronic and running characteristics are required.

That is, when the roughness is lowered to improve the electronic properties, that is, when the content of the filler is small, the polymer has a large contact energy on the surface, so that the running performance is very poor due to the so-called blocking phenomenon that the processing roll or the film sticks together. Processing efficiency is extremely low.

Generally, in order to improve such a phenomenon, a method of securing stable running property by adding a lubricating agent when coating is used when manufacturing a polyester film. However, as the amount of activator added increases, the running performance is improved. There is a problem that the yield is poor in the manufacturing process.

In addition, a virgin chip and a reclaimed chip may be used as a treatment method of the reclaimed chip, which is indispensably produced during the manufacture of the film, but the surface of the film due to the foreign matter of the reclaimed chip may be used. Particle generation can cause large dropout when using magnetic tape.

In addition, compared to the version chip, the reclaimed chip is more unstable in thermal properties of the polymer, and when the filler is contained, the stretched polymer is separated from the magnetic tape when the magnetic tape is driven when the filler is stretched. The wear resistance is also poor.

The present invention is to reduce the roughness of any one side of the film by using a reclaimed chip (Reclaimed Chip) to reduce the roughness of the film to reduce the dropout (Drop Out) in the manufacture of magnetic tape, while the other ( That is, the roughness of the running surface) is to provide a method for producing a polyester film that does not cause scratches by adjusting the outer layer thickness to have good slidability and wear characteristics.

1 is a cross-sectional state diagram of a three-layer structure film produced according to an embodiment of the present invention.

The present invention solves the above problems by producing a magnetic tape having a high functionality by coextrusion method of three or more layers using a reclaimed chip, excellent electronic properties, excellent running and wear resistance, polyester does not cause scratches, etc. As a result of the research to develop the film, in the coextrusion of the polymer with limited thickness of the coextruded layer, the coextruded layer of the reclaimed chip and the virgin chip layer are coextruded and the outer layer has a different thickness. By designing the roughness, the desired magnetic tape could be manufactured.

Polyester film for achieving the above object has a structure of at least three layers of sheet before stretching, the critical viscosity of the intermediate layer polymer is 0.5 kV / g to 0.6 kV / g and the average particle diameter of 0.4㎛ A reclaimed chip containing 1 to 3% by weight of particles having a thickness of 2.0 μm so that the average roughness is 30 nm or more, and the critical viscosity of the outermost polymer made of the same polymer as that of the intermediate layer is 0.6 ㎗ / g to 0.7 ㎗ It can be prepared by designing a virgin chip containing 0.01 wt% to 3 wt% of particles having a particle size of 0.001 µm to 1 µm / g and a mean roughness of 13 nm or less.

As described above, in order to reduce the cost of the film, in order to simultaneously improve the electronic properties and runability, which are the main quality of the polyester film, the thickness of the outer layer of the three or more layers of the coextruded polyester film is different. It is designed to be smooth so as to have excellent electronic characteristics, and the other side is designed to form surface projections so that the contact area is reduced to have an active activity.

At this time, if the thickness of the outer layer having the virgin chip is not more than 3㎛ the surface protrusion may be formed by the filler of the intermediate layer having the reclaimed chip, it is difficult to maintain smoothness, and Reclaimed chip particles contained as fillers affect the average roughness of the outer layer, and when the outer layer thickness of the running surface becomes 3 µm or more, the running performance becomes very poor due to the blocking phenomenon, and the efficiency of production and processing is extremely high. Not only is it lowered, but also scratches are generated in the machining process, so that the thickness of the other outer layer for imparting runability is preferably maintained at 2 µm or less.

In addition, in order to maximize the utilization of the reclaimed chip, the coating surface should be at least 3㎛, and if it is below 3㎛, it is difficult to obtain the expected electronic effect, and the driving surface should be below 3㎛. If it is difficult to obtain the effect of the expected electronic properties and the running surface is 3㎛ or more, the surface projection is not formed, it is difficult to expect the desired running and wear resistance, and the probability of scratches increases.

In addition, for the purposes of the invention, the roughness of the outer both sides can be achieved by controlling the thickness of each layer by predicting the surface roughness by varying the outer layer thickness.

The method of manufacturing the polymer of the outer layer is not subject to any particular limitation, and the polymerization method of polyester conventionally used is applied as it is, but the filler content of the polymer may be determined by adjusting the amount of the additive in the polymerization step. In order to adjust the surface properties such as winding and the like, inorganic particles or organic particles may be appropriately selected and added to the polyester.

For example, the inorganic particles insoluble in polyester may be known particles such as calcium carbonate, dolomite, class spare, fiberglass, talc, kaolin, mica, silica, barium sulfate, aluminum silicate, alumina, and the like. However, in order to achieve the object of the present invention, the average particle diameter of the filler used in the outer layer may be managed to be 1 μm or less.

Also, organic particles insoluble in polyester include a copolymer of a monovinyl compound having one aliphatic unsaturated bond in a molecule and a compound having two or more aliphatic unsaturated bonds in a molecule with a crosslinking agent, a thermosetting phenol resin, a thermosetting epoxy resin, Fine particles of thermosetting iodide, benzoguanamine resin and fluorine resin may be used, and there are no particular limitations on the type and amount of these, but in the experience of the present inventors, the filler used in the outer layer has an average particle diameter of 0.001 μm to 1 μm. It is suitable to add 3% by weight to 3% by weight, and it is more preferable to mix and use two or more kinds of particles selected from the above particles.

The method for producing a polyester sheet having a structure of three or more layers is not particularly limited, and conventionally known coextrusion methods may be used. For example, a polymer melted in a multi-manifold die or a feedblock die may be used. A continuous sheet can be produced by fixing a plate-like molten polymer to a rotating cooling drum by feeding.

In the case of using the multi-manifold method, the thickness of the outer layer may be controlled by adjusting the die lip gap of the outer layer, and when using the feed block die, the thickness of the outer layer may be controlled by adjusting the discharge amount and the choke bar of each layer.

The sheet produced in this way may be subjected to the continuous drawing process using any one step or multi-step drawing method, and the film adhesion between the longitudinal drawing and the transverse drawing without departing from the surface properties of the present invention. In-line coating may be performed to improve the stiffness, antistatic property, and corona discharge treatment after lateral stretching.

Since the polyester film obtained by the present invention utilizes a reclaimed chip, it is inexpensive, has excellent electronic characteristics, has excellent running performance, does not cause scratches, and has all functions as a magnetic tape for high density recording.

Hereinafter, an intermediate layer (2) made of reclaimed chips, a coating surface (3) made of virgin chips, and a running surface (4) made of virgin chips, as shown in FIG. The constructed polyester film 1 is prepared as in the examples and will be described in detail.

Example 1

Dimethyl terephthalate, 100 parts of ethylene glycol and 70 parts of a calcium carbonate (CaCO ₃₎ has an average particle diameter in the system of 0.5㎛ subjected to a transesterification reaction and a transesterification reaction was completed over 4 hours into a reactor, 0.05 part of calcium acetate 0.3 After addition, 0.06 part of trimethyl phosphate and 0.04 part of antimony trioxide were added, and polymerization was carried out for 5 hours according to a conventional method to obtain an outer layer polyester having a limit viscosity (IV) of 0.630.

After drying the polyester obtained above, it is designed to be extruded through the first extruder by a conventional method for producing a coextruded polyester film to go to the outer layer of the sheet using a feed block, and the average particle diameter, which is a by-product when manufacturing the film, is 1.0 μm. The reclaimed chip containing 0.2 wt% of phosphorus chip was put into the second extruder and designed to be fed to the middle layer of the sheet by using a feed block, and the thickness of the outer layer was controlled by using a choke bar. An amorphous sheet having was obtained.

Subsequently, the amorphous sheet having a three-layer structure obtained from the above was stretched 3.5 times at 90 ° C. in the longitudinal direction, 4.3 times at 110 ° C. in the transverse direction, and then heat-treated at 210 ° C. for 3 seconds, and the thickness of each layer was 3 μm. , 10 μm, 1 μm films were prepared, and the average roughness of the coated surface was 8 nm and the average roughness of the running surface was 20 nm. .

Example 2

A polyester film having a three-layer structure was prepared by the same method as in Example 1, except that the chip surface contained in the intermediate layer had a reclaimed chip containing 0.2% by weight of 1.5 µm, and the roughness of the coated surface was 8 nm. And a film having a roughness of 23 nm of the running surface were prepared, and Table 2 summarizes the macroparticles, the activating properties, the running characteristics, and the like.

Example 3

A polyester film having a three-layer structure was prepared by the same method as Example 1, except that the thickness of the intermediate layer containing the reclaimed chip contained in the intermediate layer was 9 µm, the thickness of the coating surface was 4 µm, and the thickness of the running surface was The film was prepared by adjusting the thickness to 1 μm, and the large particles, the activity, the running characteristics, and the like are summarized in Table 2.

Example 4

A polyester film having a three-layer structure was prepared by the same method as in Example 1, except that the coating layer had a thickness of 4 μm, the middle layer had a thickness of 10 μm, and the running surface had a thickness of 0.5 μm. A film having a thickness of 8 nm and a roughness of 25 nm of a running surface was produced, and Table 2 summarizes the macroparticles, the activity, the running characteristics, and the like.

Example 5

A polyester film having a three-layer structure was prepared by the same method as in Example 1, except that the coating layer had a thickness of 4 μm, the middle layer had a thickness of 8 μm, and the running surface had a thickness of 2.0 μm. The film with the roughness of 8 nm and the roughness of the running surface of 15 nm was produced, and Table 2 summarizes the macroparticles, the activity, the running characteristics and the like.

[Comparative Example 4]

As used in Example 1, films having a thickness of 14 μm were obtained using a reclaimed chip alone containing 0.2 wt% of particles having an average particle diameter of 1.0 μm as a by-product during film production. Although the average roughness of this film was 30 nm and the winding property was good, a film showing surface characteristics unsuitable for use of a magnetic tape during coating was obtained, and macroparticles, migration activity, running characteristics, and the like are summarized in Table 2.

Comparative Example 2

A polyester film having a three-layer structure was prepared by the same method as in Example 1, except that the polyester film was adjusted to have a thickness of 3 μm, a middle layer of 8 μm, and a running surface of 3.0 μm. The prepared particles are summarized in Table 2.

Comparative Example 3

A polyester film having a three-layer structure was prepared by the same method as in Example 1, except that the thickness of the coating layer was 3 μm, the thickness of the intermediate layer was 8 μm, and the thickness of the running surface was 3 μm. Using a shunt block, a film having an average surface roughness of 20 nm was prepared using the same resins of the intermediate layer and the traveling surface layer.

[Comparative Example 4]

In Example 1, a film having a thickness of 14 μm was prepared by blending the vertical 80% used for the coating layer and the running surface and the 20% reclaimed chip used as the intermediate layer, and summarized the macroparticles, mobility, and running characteristics in Table 2. It was.

The thickness, limit viscosity (IV), and roughness of each layer of the film prepared from Examples 1 to 5 and Comparative Examples 1 to 4 are as shown in Table 1 below.

TABLE 1

In Table 1, the thickness of each layer was observed by electron microscopy of the cross section of the film cut using a micro-tom, and the limit viscosity was measured by dissolving the polymer in ortho-chlorophenol, followed by SKTVIS-5000 (SKC Co., Ltd.) automatic viscometer The average particle diameter was obtained by magnifying 50 sites at 50,000 times using a scanning electron microscope, and measuring the particle size by arithmetic average by using an image analyzer.

TABLE 2

The measurement elements listed in Table 2 above were recorded according to the following criteria.

[Big particle]

When microscopic observation of the number of projections of 1.0 ㎛ or more formed in the size of 50 × 50 when bonding two films

When there are 0 projections of 1.0㎛ or more formed in the size of 50 × 50: ◎

When there are 1-3 projections of 1.0㎛ or more formed in the size of 50 × 50: ○

When 4 ~ 5 projections of 1.0㎛ or more formed in the size of 50 × 50: △

If there are 6 or more projections of 1.0㎛ or more formed in the size of 50 × 50:

[scratch]

By visual observation in polarized light

0 scratches per 10cm width: ◎

1 ~ 3 scratches per 10cm width: ○

3 ~ 10 scratches per 10cm width: △

10 or more scratches per 10 cm width: ×

[Activity (driving friction coefficient)]

Using the TBT-300D, a tape running tester of the Yokohama Systems Research Institute, Japan, the tape slitting the film 1/2 inch wide was fixed at a contact speed of 135 ° with a driving speed of 3.3 cm / sec and a pull-out force of 30 g. The winding tension when the material (SUS303) was passed through 90m was measured and substituted in 1 below to determine the running friction coefficient.

[Equation 1]

K = [2.303 / θ] log [Ti / To]

Θ is the contact angle of the film and the guide pin and Ti and To are the take-up and winding tension, respectively.

Travel friction coefficient below 0.25: ◎

In case of driving friction coefficient 0.25 ~ 0.35: ○

In case of driving friction coefficient 0.35 ~ 0.40: △

If the driving friction coefficient is more than 0.40: ×

[Wear resistance]

At the end of the activity, the degree of white powder (白粉) buried in the fixing guide pin was evaluated in four steps.

Almost no minute question: ◎

1 ~ 5% area of guide pin: ○

5 ~ 10% area of guide pin: △

More than 10% of the guide pin area: ×

[Electronic Characteristics]

Using a polyester film prepared according to the present invention to adjust the video tape, using a BR6400 type VTR deck made by Nippon Victor, the size of the noise signal compared to the signal output of the measurement frequency is 4M Hz.

More than 1.0dB compared to routine (Comparative Example 4): ◎

More than 0.4dB compared to routine (Comparative Example 4): ○

In case of the same level as the routine (Comparative Example 4): △

Less than or equal to routine (Comparative Example 4): ×

As can be seen from Table 2, in Examples 1 to 5 of Examples 1 to 3 of the present invention, the macroparticles, the scratches, and the electronic properties are very excellent, and the activity and wear resistance are excellent. In the case of Example 4, only abrasion resistance was shown to be moderate, and the macroparticles, scratches, diactivities and electronic properties were found to be very good, and in Example 5, the scratches and diactivities were found to be excellent, and the macroparticles, Wear resistance and electronic properties are very good, it can be seen that Natnam.

However, in the case of Comparative Example 1, it was found to be very excellent in scratch and diactivation, and the wear resistance was shown to be moderate. However, in the case of Comparative Example 2, it was shown that the particles were 6 or more, and the electronic properties were poor. The macroparticles and wear resistance are very excellent, and the electronic properties are excellent, but there are more than 10 scratches and poor in terms of active activity. In Comparative Example 3, the macroparticles, scratches, and electronic properties are very good. Although excellent in the activity and wear resistance, it is usually shown above, but in terms of manufacturing cost, there is a problem falling in Examples 1 to 5 using the reclaimed chip in the intermediate layer.

In addition, Comparative Example 4 is shown to be a general or more than the general properties by the method that is routinely prepared, there is a problem that the overall properties are generally lower than the Examples 1 to 5 manufactured by the present invention.

As described above, the polyester film produced by the manufacturing method of the present invention is not only excellent in terms of manufacturing cost, but also has an excellent advantage as a magnetic tape.

Claims (3)

In the method for producing a polyester film in which the repeating unit is composed of ethylene terephthalate or ethylene naphthalate, the sheet before stretching has a structure of at least three layers or more, and the critical viscosity of the interlayer polymer is 0.5 kPa / g to 0.6 kPa Reclaimed chip containing 1% to 3% by weight of particles having a mean particle size of 0.4 µm to 2.0 µm / g and having an average roughness of 30 nm or more, and the outermost polymer of the same polymer as the intermediate layer A virgin chip containing 0.01 wt% to 3 wt% of particles having a viscosity of 0.6 μg / g to 0.7 μg / g and an average particle diameter of 0.001 μm to 1 μm, so that the average roughness of a single layer is 13 nm or less. Method for producing a polyester film characterized in that. The method of manufacturing a polyester film according to claim 1, wherein the sum of the outermost layer thicknesses is 3 µm to 10 µm. The method for producing a polyester film according to claim 1 or 2, wherein the coating layer has a thickness of 3 µm or more and the running surface layer has a thickness of 3 µm or less.

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