KR0135584B1 - Polyester film - Google Patents

Abstract

The present invention improves the surface properties, abrasion resistance and scratch resistance of the film by using theta alumina, hard calcium and / or spherical silica together as a lubricant added to the polyester film, and at the same time surface treatment with a polymer value to the magnetic material and It is related with the polyester film which improved the adhesiveness of. That is, in a polyester film in which at least two kinds of inert particles are added to a polyester and uniaxially cultured, theta alumina having an average particle diameter of 0.005 to 3 µm and a Mohs hardness of 6 or more is 0.01 to the total weight of the polyester as the inert particles. To 4%, at least one of hard calcium carbonate having an average particle diameter of 0.01 to 3 µm and spherical silica having an average particle diameter of 0.1 to 1 µm, each 0.01 to 4% based on the total weight of the polyester, and at least one side of the film The polyester film, which is surface-treated with a dispersible polymer resin, has excellent surface smoothness, particularly excellent wear resistance and scratch resistance, and improves adhesion to a magnetic material, and thus is particularly used for magnetic recording media. Suitable for

Description

Polyester film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester film, and more particularly, to surface properties, abrasion resistance, and a polyester film using a combination of theta alumina, hard calcium, and spherical silica as a lubricant added to a polyester film.

The lollyester film represented by polyethylene terephthalate (hereinafter abbreviated as PET) has a stable structure, which is chemically stable, has high physical and mechanical strength, and is excellent in heat resistance, durability, and chemical resistance. It is widely used in many applications such as materials, photographic films, labels, packaging, various medical and industrial applications, as well as substrates of magnetic recording media.

The polyester film is formed with irregularities on the surface of the polyester film by injecting inorganic materials such as calcium carbonate, silica and kaolin as lubricants in order to provide runability, processability and desirable surface properties, particularly for use in magnetic recording media. .

However, among the lubricants commonly used for the above purposes, calcium carbonate, especially hard calcium carbonate, has an advantage in that it is effective in controlling the surface properties of the film, but due to its low hardness, the particles wear off during the running of the film and the film is dropped. In addition to scratches on the surface, the adhesiveness with the magnetic material is low, causing a drop-out when manufactured with magnetic tape.

As a conventional technique for improving the scratch resistance and adhesion to a magnetic body of a polyester film, alumina is mixed with a low hardness hard calcium carbonate as disclosed in Japanese Patent Laid-Open No. 3-24134 and the polyester By surface treatment with a water-based thermoplastic resin, a method of imparting surface properties of a film, improving abrasion resistance and scratch resistance, and improving adhesion to a magnetic body has been proposed.

However, when the lubricant is used for a polyester film, it must be prepared by adding a slurry of high concentration, but due to the thickening phenomenon, the slurry is not only difficult to prepare, but also has a high viscosity, resulting in a problem that the stability of the slurry is lowered.

Therefore, in the present invention, in order to solve the above problems, it is possible to manufacture a high concentration of slurry, excellent in stability of the slurry, excellent in controlling the surface properties of the polyester film, and excellent in scratch resistance and wear resistance while driving, It aims at providing the polyester film excellent in adhesiveness with a magnetic body.

The polyester film of the present invention for achieving the above object is a polyester film in which at least two kinds are uniaxially cultured by adding at least two kinds of inert particles in polyester, wherein the inert particles have an average particle diameter of 0.005 to 3 um and a Mohs hardness. Theta alumina of 6 or more is added in an amount of 0.01 to 4% based on the total weight of the polyester, and at least one surface of the film is surface treated with a polymer resin capable of water dispersion.

It is preferable to use at least one of an acrylic resin, a polyester resin, and an acrylic-polyester resin as the polymer resin for surface-treating at least one surface of the film.

Theta-alumina has a monoclinic system among various kinds such as α-, β-, γ-, δ-, χ-, η-, θ- and κ-alumina which are formed during the heat treatment of alumina hydrate. Slurries prepared using the same have a particularly low viscosity, so that problems due to high viscosity do not occur and stability of the slurry is improved. Therefore, when the film is prepared by adding and stretching theta alumina to the polyester, a polyester film having excellent surface properties and improved abrasion resistance and scratch resistance can be prepared. However, when only theta alumina is used as an inert additive, scratch resistance is achieved. However, if the base film surface is too smooth to form a large protrusion, it is possible to improve the running performance than when only theta alumina is added alone. In addition, when the at least one surface of the polyester film is surface treated with a polymer resin capable of water dispersion, it is possible to improve the adhesiveness with the magnetic body during the manufacture of the magnetic recording medium.

As for polyester of this invention, PET obtained by carrying out the condensation reaction of dimethyl terephthalate and ethylene glycol 80 mol% or more of a repeating unit is preferable, and homopolyester or copolyester may be sufficient as it. In the case of copolyester, other copolymerization components include isphthalic acid, para-betaoxyethoxy benzoate, 2,6-niphthalenedicardic acid, 4,4'-dicarboxyl diphenyl, 4,4'-dicar Dicarboxylic acid components such as benzobenzone, bis (4-card carboxydiphenyl) ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, and propylene glycol, butanediol, neopentyl glycol, diethylene glycol , Oxycarboxylic acid component components such as cyclohexanedimethanol, paraoxybenzoic acid and the like, and the like can be used.

The polyester of the present invention can be applied to any of the transesterification method and the direct polymerization method, and any of batch and continuous methods can be employed.

In the case of the transesterification method, there is no particular limitation on the transesterification catalyst, and conventionally known ones can be used. For example, among the magnesium compound and the cobalt compound, the zinc compound and the manganese compound, those which are soluble in the reaction system can be selected and used.

There is no restriction | limiting in particular also about a polymerization catalyst, An appropriate thing can be selected and used among an antimony compound and a barium compound.

As the inert particles to be added to the polyester film of the present invention, theceta alumina has an average particle diameter of 0.005 to 3 µm and a Mohs hardness of 6 or more to 0.01 to 4%, and the hard calcium carbonate has an average particle diameter of 0.012 to 4%. Hard calcium carbonate is added, and the average particle diameter is 0.01 to 3 µm, and the spherical silica is 0.01 to 4% by adding at least one of 0. 'to 1 µm. Abrasion resistance and scratch resistance can be improved.

In the case of theta alumina, when the average particle diameter is smaller than 0.005 μm, the surface roughness of the film is lowered to increase the coefficient of friction, and thus the running performance is poor. When the film using particles larger than 3 μm is manufactured with magnetic tape, the surface properties are It will be disoriented. Preferably, theta alumina having an average particle diameter of 0.01 to 1.5 mu m is used. When the theta alumina is added in an amount of less than 0.01%, the running friction coefficient of the film is high, resulting in poor processability, and when the amount is more than 4%, coarse particles are generated due to the flocculation phenomenon of the lubricant, which is dropped when the magnetic tape is manufactured. Out phenomenon appears. Preferably used in an amount of 0.05 to 2%.

In addition, when hard calcium carbonate is used having an average particle diameter of less than 0.01 μm, the film roughness in the film is lowered and the friction coefficient is increased, resulting in poor runability. When a film using particles larger than 3 μm is manufactured with magnetic tape, Properties are degraded. Preferably, hard calcium carbonate having an average particle diameter of 0.2 to 2 µm is used.

On the other hand, when the average particle diameter of the spherical silica is smaller than 0.1 μm, the film roughness of the film decreases and the friction coefficient is increased, resulting in poor running performance. Is lowered. Preferably, spherical silica having an average particle diameter of 0.15 to 0.7 mu m is used.

Here, the hard calcium carbonate and the spherical silica are poor in workability due to the high running friction coefficient of the film when the amount is added in an amount of less than 0.01 to 4%. Physical properties are degraded. Preferably each is used in an amount of 0.05-2%.

The hard calcium carbonate, spherical silica and theta alumina added to the polyester in the present invention may use a dispersant to prepare an ethylene glycol slurry.

In addition, the polyester film of the present invention is surface-treated with a polymer resin that can be dispersed in order to improve the adhesion to oily materials in the manufacture of the magnetic recording medium. It is preferable to use at least one of polyester-based, acrylic-based and acrylic-polyester-based resins as the surface treating agent, and it is appropriate to set this concentration to 1 to 15% at the time of water dispersion.

In the present invention, a method for producing a polyester film is not particularly limited, and a method for producing a polyester film having a molecular weight of about 20,000 including the above additives is not particularly limited, and has a molecular weight of about 20,000 including the above additives. A polyester is made of an unstretched sheet melt-extruded by the tee-die method, etc., and then biaxially stretched to make a biaxially cultivated polyester. Prepare ester film. The stretching method is the same as that of ordinary polyester, and there is no change in the manufacturing process by the above additives. The stretching temperature is 60 to 150 占 폚, the stretching ratio is 2.5 to 6.0 times in the longitudinal direction and 2.5 to 6.0 times in the lateral direction.

The polyester film of this invention can be made into an appropriate thickness | variety according to a use, Usually, it manufactures with a film of 2.0-200 micrometers.

The present invention will be described in more detail with reference to the following examples. However, the following examples are only examples of the present invention and the present invention is not limited thereto.

Various performance evaluations of the films produced in Examples and Comparative Examples of the present invention were carried out by the following method.

(How to measure)

1) Average particle diameter

It is the volume average particle diameter which measured the ethylene glycol slurry using the centrifugal particle size measuring device of Shimadzu Corporation (Japan).

2) viscosity

The Brookfield B type viscometer was used to measure the viscosity of the slurry at a normal speed of 60 rpm at normal temperature.

3) molecular weight

The molecular weight of the polymer was measured using a water molecular weight measuring apparatus using a metacresol as the mobile phase, a flow rate of 1 ml / min, and a column temperature of 100 deg.

4) surface smoothness

Surface roughness of 30 mm in length, 20 mm in width and 50 μm in thickness was measured using a surface roughness gauge of Kosaka Research Institute (Japan) by contact method.

Center line average roughness (Ra): When a straight line parallel to the average line of the roughness curve is drawn, it is the height of the straight line where both areas of the straight line are equal.

Centerline maximum height (Rt): The distance between the maximum height and the minimum depth in the measurement section.

The lower the average roughness and the maximum height, the better the smoothness and the better the cohesiveness.

5) wear resistance

The tape cohesion tester of Yokohama System Research Institute (Japan) is used.The film is 1/2 inch wide and the slitting tape is run at 3.3cm / sec. As observed, wear resistance is evaluated as the degree of white powder generated around the guide pin.

A: When there is no powder at all on the guide pin

B: When 100% of the guide pin generates 1/5 of the guide pin area

C: When 100% of the guide pin generates half of the guide pin area.

D: When the overall amount of powder on the guide pin

6) scratch resistance

The tape running tester of Yokohama System Research Institute (Japan) is used.The tape slitting the film 1/2 inch wide is run at a driving speed of 3.3 cm / sec and two running times to observe the damaged surface of the film with a microscope. At this time, the scratch resistance was evaluated with and without the stretch wire around the tape width.

◎: Excellent scratch property (damaged scratch wire is 2 lines or less)

○: Good scratch resistance (damaged scratch wires are 3 to 4 wires)

(Triangle | delta): Scratch-resistant ordinary (damaged scratch wire is 5 wire | wire-6 wire | wire)

×: scratch-resistant (damaged scratch lines are 7 or more lines)

7) Adhesive

The tape adhesion tester of Shin-Dong Chemical (Japan) was used, and the adhesiveness was evaluated to the extent of the validity at the time of peeling after the film was adhered to the adhesive tape.

◎: excellent adhesion (more than 600g of peeling force)

○: Good adhesiveness (peel strength 300 to 600 g)

(Triangle | delta): Adhesive normal (100-300 g of peeling force)

X: poor adhesiveness (less than 100 g of force)

Example 1

Polycondensation of PET is carried out by a conventional method, but 0.20% of spherical silica with an average particle diameter of 0.50 µm, 0.02% of hard calcium carbonate with an average particle diameter of 0.53 µm, and 0.02% of spherical salacurule with an average particle diameter of 0.50 µm are added to obtain a molecular weight of about 20,000. Melt-extruded polymer to make an unstretched sheet, stretched 3.0 times in the longitudinal direction at 90 ℃ to prepare a biaxially stretched film having a thickness of 50㎛, surface treatment of one side thereof with an acrylic resin, and then performance evaluation It was.

The performance evaluation results of the film are shown in [Table].

Example 2-3

The same procedure as in Example 1 was carried out, but biaxially oriented films were prepared by adding hard calcium carbonate, spherical silica, and theta alumina as shown in the following [Table], and a single side thereof was an acrylic resin, a polyester resin, or an acrylic poly After surface treatment with ester resin, the performance evaluation of the film was performed, and the result was shown to [table].

[Comparative Example 1-9]

In the same manner as in Example 1, except that hard calcium carbonate, gamma- or delta-alumina was added alone or in combination as shown in the following table to prepare a biaxially oriented film, and without surface treatment. The performance of the film was evaluated and the results are shown in [Table].

As shown in the following table, a polyester film prepared by adding hard calcium carbonate and spherical silica and / or theta alumina and surface-treating with an acrylic resin, a polyester resin, or an acrylic-polyester resin, It can be seen that the wear resistance and scratch resistance are superior to the film without surface treatment, and in particular, the adhesion is improved.

Therefore, the polyester film of the present invention is not only suitable for use in a magnetic recording medium in which adhesion with a magnetic material is an important problem, but also in abrasion and scratch resistance such as graphics, stamping foil, electrical insulating material and packaging. It can also be effectively used for the purpose.

* The viscosity was measured by 20 weight% of slurry in alumina.

Claims (2)

An at least uniaxially oriented polyester film comprising at least two kinds of inert particles, wherein at least one surface of the film is surface treated with a polymer capable of dispersing water, wherein one of the inert particles has an average particle diameter of 0.005 to 3 µm and a Mohs hardness. At least one of hard calcium carbonate having an average particle diameter of 0.01 to 3 µm and spherical silica having an average particle diameter of 0.1 to 1 µm, and the content of theta alumina is 0.01 to 4 relative to the total weight of the polyester. And a total amount of the hard calcium carbonate and the spherical silica is 0.01 to 4% by weight based on the total weight of the polyester. The polyester film according to claim 1, wherein the polymer resin is at least one of an acrylic resin, a polyester resin, and an acrylic-polyester resin.