KR19990070961A - Biaxially Oriented Polyester Film and Manufacturing Method Thereof - Google Patents

Abstract

The present invention relates to a biaxially oriented polyester film which is excellent in wear resistance and can reduce the dropping of lubricant. A biaxially oriented polyester film according to the present invention is a first film layer made of a polyester resin containing 0.05 to 3% by weight of particles insoluble in polyester, inert and having an average particle diameter of 0.1 to 5.0 µm, the first A second film layer laminated on top of the film layer and containing no particles, and having a thickness of 0.5 to 1.5 μm, and laminated below the first film layer and containing no particles; It is made of a polyester-based resin, characterized in that it comprises a third film layer having a thickness of 0.5 to 1.5㎛.

Description

Biaxially Oriented Polyester Film and Manufacturing Method Thereof

The present invention relates to a polyester film and a method for producing the same, and more particularly, to a biaxially oriented polyester film excellent in running resistance, abrasion resistance, and resistance to glide loss from the film, and a method for producing the same.

Polyester, represented by polyethylene terephthalate (PET), has a stable chemical structure and mechanical strength, and is excellent in heat resistance, durability, chemical resistance, and the like, and is used for capacitors, medical, industrial, packaging, photo film, labels, and magnetic. It is used for various purposes, such as a base film of a recording medium.

However, the polyester film has a problem in post-processing or product characteristics due to wear of the surface due to the roll, etc., as the processes such as the printing process for packaging, the magnetic material application process for the magnetic recording medium, the calendering process, and the slitting process are accelerated. Occurs. In particular, in the case of magnetic recording media, inorganic or organic particles such as calcium carbonate, silica, kaolin, alumina or the like are added to improve runability and processability, but irregularities are formed on the surface of the polyester film. As cotton, the electronic properties are lowered, the added inert particles are dropped off, and film wear is increased.

Recently, in accordance with the trend of high performance of magnetic recording media, a flatter film is required to improve the electron conversion characteristics. On the other hand, in order to increase the film production speed, driving resistance, abrasion resistance, and resistance to slippage from the film are increased. Required.

Furthermore, as the process speeds up, the film is subjected to more severe conditions such as an increase in tension applied to the film. Accordingly, lubricants are dropped from the film, causing foreign matter or contamination during the process, or used in the manufacture of magnetic tape. It can also cause data loss, a so-called drop-out.

Accordingly, the technical problem to be achieved by the present invention is to provide a biaxially oriented polyester film for a magnetic recording medium having excellent running property, abrasion resistance, and resistance to slipping off from the film.

Another technical problem to be achieved by the present invention is to provide a method for producing the biaxially oriented polyester film.

In order to achieve the above technical problem, the present invention is a first film layer made of a polyester-based resin containing 0.05 to 3% by weight of particles insoluble in polyester, inert and having an average particle diameter of 0.1 to 5.0㎛; A second film layer laminated on the first film layer and made of a polyester-based resin containing no particles, and having a thickness of 0.5 to 1.5 µm; And a third film layer laminated on the lower part of the first film layer, the polyester-based resin containing no particles, and having a thickness of 0.5 to 1.5 µm. Provide a film.

In order to achieve the above-mentioned other technical problem, the present invention also provides a method of (a) extruding a polyester-based resin melt containing 0.05 to 3% by weight of particles which are insoluble in polyester, inert, and have an average particle diameter of 0.1 to 5.0 µm. At the same time, a melt layer composed of three layers was formed by stacking a polyester-based resin melt containing no particles at the same time above and below the first film layer and co-extrusion to a second film layer and a third film layer, respectively. Manufacturing step; (b) cooling and solidifying the melt sheet to prepare an undrawn sheet; And (c) provides a method for producing a biaxially oriented polyester film comprising the step of stretching the unstretched sheet so that the thickness of the second and third film layer is 0.5 to 1.5㎛ respectively.

In this invention, it is preferable that the sum of the thickness of the said 1st, 2nd, and 3rd film layer is 1-50 micrometers.

In the present invention, the insoluble and inert particles are calcium carbonate, dolomite, glass fiber, talc, mica, kaolin, silica, barium sulfate, aluminum silicate, alumina, monovinyl compounds and molecules having one aliphatic unsaturated bond in molecular structure It is preferable to include at least one selected from the group consisting of a copolymer with a compound having two or more aliphatic unsaturated bonds in the structure, a thermosetting phenol resin, a thermosetting epoxy resin, a thermosetting urea resin, a benzoguanamine resin, and a fluorine resin. .

The biaxially stretched polyester film according to the present invention has a structure in which an upper surface and a lower surface of a first film layer including a lubricant added to impart runability are laminated with second and third film layers not containing a lubricant. . When the film is stretched, the lubricant particles move in the surface direction of the film (thickness direction of the film) to form protrusions on the surface of the film, thereby reducing the contact area with the roll during traveling, thereby improving running performance. However, at this time, since the second and third film layers not containing the lubricant surround the lubricant particles protruding to the surface of the first film layer, the lubricant particles are difficult to fall off from the biaxially stretched polyester film according to the present invention.

Hereinafter, the biaxially oriented polyester film according to the present invention will be described in more detail.

In the present invention, the polymerization raw material used in the preparation of the polyester resin used as the base film is a terephthalic acid (or dimethyl terephthalate), isophthalic acid, 2,6-naphthalene dicarboxylic acid, 4, as a dicarboxylic acid component. 4'-dicarboxyl diphenyl and 4,4'- dicarboxy benzophenone, and ethylene glycol, propylene glycol, butanediol, etc. are mentioned as a diol component.

The polyester according to the present invention can be produced by any of the transesterification method and the direct polymerization method, and any of batch and continuous processes can be employed in the process configuration.

In the case of using the transesterification method, there is no particular limitation on the transesterification catalyst, and any conventionally known one can be used. For example, alkali earth metal compounds such as magnesium compounds, zirconium compounds, sodium compounds, potassium compounds, calcium compounds and barium compounds, and cobalt compounds, zinc compounds, and manganese compounds may be used that are soluble in the reaction system.

The polymerization catalyst is also not limited, but it is preferable to use an appropriately selected from antimony compounds, germanium compounds, and titanium compounds.

On the other hand, as mentioned, in the first film layer (middle layer) of the polyester film according to the present invention, insoluble and inert particles of a polyester having an average particle diameter of 0.1 to 5 탆, more preferably 0.1 to 3 탆, are used as lubricants. 0.05 to 3% by weight, more preferably 0.1 to 2% by weight based on the weight of the first film layer is contained, the lubricant is contained in the second and third film layers (outer layers) covering the first film layer. Not included.

At this time, the lubricants used are calcium carbonate, dolomite, fiberglass, talc, mica, kaolin, silica, barium sulfate, aluminum silicate, alumina, monovinyl compound having one aliphatic unsaturated bond in molecular structure and two in molecular structure. Copolymers with compounds having the above aliphatic unsaturated bonds, thermosetting phenol resins, thermosetting epoxy resins, thermosetting urea resins, benzoguanamine resins, and fluorine resins. It is more effective to mix and use two or more kinds of the above lubricants.

If the lubricant is contained in the second and third film layers which are outer layers, the effect of preventing the lubricant from falling off is insignificant. When the lubricant of the first film layer is less than 0.05% by weight, roughening of the surface of the film is insignificant, and driving and abrasion resistance are not improved. When the lubricant is more than 3% by weight, coarse particles are produced due to the coagulation of the lubricant particles. In the case of magnetic tape, a so-called drop-out phenomenon in which data is lost is not preferable. If the average particle diameter of the lubricant of the first film layer is less than 0.1 mu m, the roughening of the film surface is insignificant, and if it exceeds 5 mu m, the electronic characteristics are poor.

In this invention, the thickness of the 2nd or 3rd film layer after biaxial stretching is 0.5-1.5 micrometers, More preferably, it is 0.5-1 micrometer, The thickness of the whole film is 1-50 micrometers, More preferably, 10 It is -30 micrometers.

If the thickness of the second or third film layer exceeds 1.5㎛ the lubricant contained in the first film layer is difficult to form the surface roughness, so the running and abrasion resistance is not sufficiently improved, if less than 0.5㎛ the thickness of the layer is too thin It is because it is unpreferable since productivity falls.

The film according to the present invention comprises a polyester film having a three-layer structure, and the method for forming the three-layer structure does not follow any particular limitation, and a conventionally known coextrusion method may be used. For example, a continuous film can be produced by supplying molten polyester to a multi-manifold die or feedblock die and fixing the plate-like molten polyester to a rotating cooling drum. In this way, it is preferable to prepare a melt coextruded unstretched sheet, and then biaxially stretch it.

The stretching method is the same as in the manufacturing method of a conventional polyester film, the stretching temperature is preferably in the range of glass transition temperature to cold crystallization temperature, the stretching ratio is 2.5 to 5.0 times in the longitudinal direction and 3.0 to 5.0 times in the transverse direction. It is desirable to. The heat treatment temperature is 180 to 230 캜, preferably 190 to 220 캜.

Hereinafter, the present invention will be described in detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

In Examples and Comparative Examples of the present invention, various performance evaluation of the produced polyester film was performed by the following method.

(1) Average particle size of particles

Using a centrifugal sedimentation particle size analyzer (SACP-II) manufactured by Shimadzu Corporation (Japan), the particles were dispersed in an ethylene glycol solvent with a lubricant, and then the volume average particle diameter (µm) was measured.

(2) surface roughness

Surface roughness was measured using a contact surface roughness meter (SURFCORDER SE-30D) of Kosaka Research Institute (Japan). The measurement conditions were the needle diameter of 2㎛, cutoff 0.08mm, and the measuring length of 5mm. After measuring at 7 points, the values at 5 points except the maximum and minimum values were averaged.

(3) layer thickness

The cross section of the film was cut out with a microtom and observed with an electron microscope.

(4) wear resistance

After slitting the film to 1/2 inch width, using a tape running tester (TBT-300H) of Yokohama Systems Research Institute (Japan), friction running on the tape guide pin at a running speed of 3.3 cm / sec, and then the surface of the guide pin Abrasion resistance was evaluated by visual observation or photographic observation of the occurrence of white powder.

A grade: when no minute powder occurs on the guide pin

Class B: 100% of the guide pin has 1/5 of the guide pin area.

C class: If the guide pin has half of the guide pin area

Class D: When a minute occurs in the whole guide pin

(5) runability

Using the tape running tester (TBT-300H) of the Yokohama System Research Institute (Japan), the film was slit in a 1/2 inch width at 20 ° C and 60 RH% atmosphere. After running at 180 degrees, the running speed was 3.3 cm / sec, and the inlet tension was set to 30 g, the outlet tension was determined, and the friction coefficient k was measured by the above equation.

k = ln (T _out / T _in )

Where T _in is the inlet tension and T _out is the outlet tension.

(6) Resistance test against dropping of lubricant

After slitting the film to 1/2 inch width, the razor is brought into contact with the film surface while running at a traveling speed of 50 m / min using a tape running tester (TBT-300H) of Yokohama Systems Research Institute (Japan). The amount of white powder on the surface of and the observation of scanning electron microscopy were combined to evaluate whether the lubricant was eliminated.

Grade A: Razor contains almost no powder and no lubricant left off

Grade B: Razor has very little white powder and if there is some dropout of lubricant

Grade C: Razor contains a lot of white powder and there are some dropouts of lubricant.

Class D: Razor has a lot of white powder and there is a lot of lubricant falling out.

(7) Observation of projections and voids

Scanning electron microscopy was used to observe the projections and voids on the surface of the film. The measurement magnification was 5000 times and the number of observed voids was measured by comparing 40 sites. Here, the void refers to an empty space in which separation between the polymer and the inert particles occurs due to lack of affinity between the inert particles added to the film and the polymer.

Example 1

100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol and 0.05 parts by weight of calcium acetate were placed in a batch reactor and subjected to transesterification. After performing the transesterification for 4 hours, 0.06 parts by weight of trimethyl phosphate and 0.04 parts by weight of antimony trioxide were added and polycondensed for 5 hours to obtain polyester A having an ultimate viscosity of 0.600. On the other hand, in manufacture of the said polyester polymer, after completion | finish of a transesterification reaction, after adding 0.4 weight% of calcium carbonate particles of 0.5 micrometer of average particle diameters, polymerization reaction was performed and polyester B was obtained.

Subsequently, after drying the polyesters A and B, a polyester sheet was formed as an outer layer, and polyester B was used as an intermediate layer. It was. Subsequently, the unstretched sheet obtained by cooling the melt sheet to 90 ° C. was stretched 3.7 times in the longitudinal direction and 4.0 times in the width direction. Subsequently, the stretched sheet was heat treated at 210 ° C. to prepare a biaxially stretched polyester film having a thickness of 14 μm, which was Polyester A: Polyester B: Polyester A 〓 1 μm: 12 μm: 1 μm. The properties of the obtained film are shown in Table 1.

Examples 2-6 and Comparative Examples 1-5

Among the conditions of Example 1, the thickness of each layer, the average particle diameter of the lubricants added to the polyester B, and the addition amount were changed to prepare films having different physical properties. On the other hand, in Comparative Examples 1 to 5 to prepare a single layer film rather than a laminated film of three layers to compare the physical properties.

The physical properties of each film thus prepared are shown in Table 1.

As shown in Table 1, when the average particle diameter and the protrusion height of the lubricant correspond to the attached range of the present invention, a polyester film having excellent runability, wear resistance, and resistance to dropping of the lubricant was obtained.

Lubricant added to polyester B (first film layer) Layer thickness ratio (A / B / A) (㎛) Surface Roughness (㎛) Wear Resistance (Grade) Resistance to dropping of lubricant (grade) Number of voids Coefficient of friction Kinds Particle size (㎛) Addition amount (% by weight) Example 1 Calcium carbonate 0.5 0.4 1/12/1 0.015 B B One 0.83 Example 2 Calcium carbonate 0.8 0.4 1/12/1 0.018 A A 2 0.71 Example 3 Calcium carbonate 1.0 0.4 1/12/1 0.020 A B 4 0.62 Example 4 Calcium carbonate 0.8 0.3 1/12/1 0.016 B A 2 0.72 Example 5 Calcium carbonate 0.8 0.5 1/12/1 0.021 A B 3 0.68 Example 6 Calcium carbonate 0.8 0.4 1.5 / 10 / 1.5 0.018 B B One 0.76 Comparative Example 1 Calcium carbonate 0.5 0.4 Structure 0.017 C B 13 0.79 Comparative Example 2 Calcium carbonate 0.8 0.4 Structure 0.020 B A 15 0.63 Comparative Example 3 Calcium carbonate 1.0 0.4 Structure 0.022 A B 18 0.60 Comparative Example 4 Calcium carbonate 0.8 0.3 Structure 0.018 B A 13 0.61 Comparative Example 5 Calcium carbonate 0.8 0.5 Structure 0.024 B B 21 0.67

As described above, the biaxially oriented polyester film of the three-layer structure according to the present invention is excellent in running, abrasion resistance, and resistance to lubricant dropping, such as photographing, graphics, OHP, magnetic recording media, packaging, and the like. It is suitable as a film.

Claims (4)

A first film layer made of a polyester resin containing 0.05 to 3% by weight of particles insoluble in polyester, inert and having an average particle diameter of 0.1 to 5.0 µm; A second film layer laminated on the first film layer and made of a polyester-based resin containing no particles, and having a thickness of 0.5 to 1.5 µm; And Biaxially oriented polyester film, which is laminated under the first film layer and is made of a polyester-based resin containing no particles, and has a thickness of 0.5 to 1.5 µm. . The biaxially oriented polyester film according to claim 1, wherein the sum of the thicknesses of the first, second, and third film layers is 1 to 50 µm. The method of claim 1, wherein the insoluble and inert particles, Calcium carbonate, dolomite, glass fiber, talc, mica, kaolin, silica, barium sulfate, aluminum silicate, alumina, monovinyl compounds having one aliphatic unsaturated bond in molecular structure and compounds having two or more aliphatic unsaturated bonds in molecular structure A biaxially oriented polyester film comprising at least one selected from the group consisting of a copolymer with a thermosetting phenol resin, a thermosetting epoxy resin, a thermosetting urea resin, a benzoguanamine resin, and a fluorine resin. (a) A polyester-based resin melt containing 0.05 to 3% by weight of particles insoluble in polyester and inert and having an average particle diameter of 0.1 to 5.0 µm is extruded to a first film layer, and at the same time, a poly-containing particle Stacking an ester-based resin melt above and below the first film layer to coextrude the second resin layer and the third film layer to produce a melt sheet including three layers; (b) cooling and solidifying the melt sheet to prepare an undrawn sheet; And (c) stretching the unstretched sheet such that the thicknesses of the second and third film layers are 0.5 to 1.5 µm, respectively.