JPH05302021A - Thermoplastic polyester composition film made therefrom - Google Patents

Abstract

PURPOSE:To obtain a film of excellent abrasion resistance by adding chi-alu minum oxide particles to a thermoplastic polyester and molding the resulting composition into a film. CONSTITUTION:A composition prepared by adding chi-aluminum oxide particles to a thermoplastic polyester is formed into a film. The aluminum oxide particles can be prepared by firing, e.g. gibbsite at 400-1100 deg.C. The specific surface area of the chi-aluminum oxide particle is desirably 10m<2>/g or above. The amount of the chi-aluminum oxide particles added is desirably 0.01-10 pts.wt. per 100 pts.wt. thermoplastic polyester.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a thermoplastic polyester composition and a film comprising the same. More specifically, it relates to a thermoplastic polyester composition suitable for obtaining a film having excellent abrasion resistance for magnetic recording media and the like, and a film comprising the same.

[0002]

2. Description of the Related Art Generally, thermoplastic polyesters such as polyethylene terephthalate have excellent mechanical properties and are widely used as molded articles such as films. Usually, for the purpose of imparting slipperiness to a molded product, the polyester is made to contain inert particles in the polyester, and a method of imparting unevenness to the surface of the molded product is performed. There are various kinds of such inert particles, but in general, there is a problem that the inert particles lack affinity with the polyester and have poor abrasion resistance.

In order to solve this problem, the surface treatment of inert particles has been studied so far, for example, Japanese Patent Laid-Open Publication No. Sho-6.
3-221158, JP-A-63-280763 (the surface of colloidal silica particles is modified with a glycol group), and JP-A-63-313345 (the surface of colloidal silica particles is modified with a coupling agent). JP-A-62-235353 (wherein calcium carbonate particles are surface-treated with a phosphorus compound) has been proposed.

However, even if such a known method is used, when particles are repeatedly rubbed like a magnetic tape, particles fall off. Therefore, it has been recently proposed to use special particles, for example,
JP-A-62-172031 (silicon particles) and JP-A-2-129230 (delta-type aluminum oxide particles) have been proposed, but they are still insufficient.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art. In particular, when a chi-type aluminum oxide particle is blended with a thermoplastic polyester to form a film, abrasion resistance is improved. It is an object of the present invention to provide a composition capable of obtaining a film having excellent properties and a film comprising the same.

[0006]

The above-mentioned object of the present invention can be achieved by a thermoplastic polyester composition containing chi-type aluminum oxide particles and a polyester film comprising the same.

The crystal structure of aluminum oxide particles can be identified by the diffraction angle 2θ value at which diffracted X-rays appear in the X-ray diffraction method. Standard for chi-type crystal structure 2
A plurality of sets of θ values are known, but the main 2θ values are 31.
4, 37.4, 42.4, 47.6, 67.3 (degrees) and the like.

FIG. 1 shows X of chi-type aluminum oxide particles.
The analysis result of the line diffraction method is shown.

Aluminum oxide particles include alpha type,
Gamma type, delta type, theta type, eta type, kappa type,
Various crystal structures such as chi-type are known, but they can be determined by the synthesis method of each particle.

The chi-type aluminum oxide particles of the present invention can be produced by firing gibbsite at, for example, 400 to 1100 ° C.

Among the aluminum oxide particles, when the chi-type aluminum oxide particles are blended with the polyester, the abrasion resistance of the film becomes very excellent.
The reason for this is unknown, but it is considered that the aluminum oxide particles having the crystal structure of the present invention have high affinity with polyester.

The primary particle diameter of the particles is quite difficult to measure because of the extremely fine particles, but it can be measured by the specific surface area. The specific surface area of the chi-type aluminum oxide of the present invention is preferably 10 m ² / g or more, more preferably 30 m ² / g or more.

Naturally, such particles cause agglomeration in polyester, but the secondary particle diameter can be arbitrarily selected according to the purpose of the film obtained by molding from the thermoplastic polyester composition. You can However, if it is too large, coarse protrusions are generated on the film surface, so that the thickness is preferably 2.0 μm or less, more preferably 0.5 μm or less. Further, it is preferably 0.01 μm or more.

The term "secondary particle diameter" as used herein means a circle-equivalent average diameter when 1,000 particles are observed with a transmission electron microscope.

The amount of chi-type aluminum oxide particles added is 0.10 with respect to 100 parts by weight of the thermoplastic polyester.
01 to 10 parts by weight is preferable, and 0.1 to 5 parts by weight is more preferable.

The proportion of the crystal structure of chi-type aluminum oxide is preferably 50% by weight or more, and particularly preferably 70% by weight or more in order that the film has good wear resistance.

The thermoplastic polyester in the present invention may be any one as long as it can form a film, for example, polyethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, polyethylene-2,6-. Naphthalene dicarboxylate or polyethylene-1,
2-bis (2-chlorophenoxy) ethane-4,4'-
Dicarboxylate is particularly preferred.

These polyesters include, as copolymerization components, dicarboxylic acids such as adipic acid, isophthalic acid, sebacic acid, phthalic acid, 4,4'-diphenyldicarboxylic acid and ester-forming derivatives thereof, polyethylene glycol, diethylene glycol, Dioxy compounds such as hexamethylene glycol, neopentyl glycol and polypropylene glycol, oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid and ester-forming derivatives thereof may be copolymerized.

The thermoplastic polyester composition of the present invention comprises
For example, chi-type aluminum oxide particles can be obtained by a production method in which glycol, which is a starting material for polyester, is mixed and stirred to form a dispersion slurry, which is added to a reaction system of thermoplastic polyester. The treatment method at this time may be, for example, ultrasonic waves or the like instead of stirring, and a medium type mill such as a sand grinder may be used.

In addition to the above-mentioned method of directly adding to the polymerization reaction system, the polyester may be blended with, for example,
It is also possible to knead chi-type aluminum oxide particles into molten polyester. The former may be added to the polymerization reaction system at any time, but is preferably from before the transesterification reaction to before the pressure reduction of the polycondensation reaction. In the case of the latter kneading, either a method of drying the particles and kneading into the polyester or a method of directly kneading in a slurry state under reduced pressure may be used.

The polyester film of the present invention can be manufactured by the following method. The polyester pellets obtained by the polymerization reaction are sufficiently dried and then immediately fed to the extruder. The pellets are melted at 260 to 350 ° C., extruded into a sheet form from a die, cooled on a casting roll and solidified to obtain an unstretched film. next,
It is preferable to biaxially stretch this unstretched film. As the stretching method, a sequential biaxial stretching method, a simultaneous biaxial stretching method, a method of stretching the biaxially stretched film again in this manner, or the like may be used. Depending on the polyester composition,
In order to obtain a sufficient elastic modulus as a film for a magnetic recording medium, it is preferable that the final stretched area ratio (longitudinal ratio × lateral ratio) is 6 times or more.

Further, in order to keep the heat shrinkage rate of the film small, it is preferable to perform heat treatment in the temperature range of 150 to 260 ° C. for about 0.1 to 60 seconds.

The film of the present invention can be used as either a single layer film or a laminated film. In the case of a laminated film, it is preferable to use the film of the present invention as the film constituting at least one surface, because the film surface will have good abrasion resistance, uniformity, and slipperiness. As a film laminating method, a known method such as melt coextrusion can be used.

The thickness of the film of the present invention (hereinafter, also referred to as a laminated portion) constituting one surface of the laminated film is 0. 0 with respect to the secondary particle diameter of the aluminum oxide particles contained therein.
It is preferable that the amount is from 1 to 20 times because the film surface uniformity and slipperiness are particularly good.

The content of chi-type aluminum oxide particles in the laminated portion is preferably 0.05 to 30 parts by weight, and particularly preferably 0.1 to 10 parts by weight.

When running properties are required, it is preferable to use inorganic particles or organic particles other than chi-type aluminum oxide in combination. Examples of such particles include inorganic particles such as calcium carbonate, titanium oxide, silicon oxide, calcium phosphate, and zirconium oxide, silicon resin, styrene-divinylbenzene copolymer, styrene-ethylvinylbenzene-divinylbenzene copolymer, ethylvinyl. Examples thereof include crosslinked polymer particles such as a benzene-divinylbenzene copolymer.

[0027]

Next, the present invention will be described in more detail with reference to Examples and Comparative Examples.

(1) Evaluation of Specific Surface Area of Aluminum Oxide Particles B. E. T. It measured according to the method.

(2) Evaluation of secondary particle size of aluminum oxide particles Aluminum oxide particles were blended with polyester,
After cutting into an ultrathin section having a thickness of 0.2 μm, the section was observed with a transmission electron microscope and evaluated by the circle-equivalent average diameter (μm) of 1000 secondary particles in an aggregated state.

(3) Evaluation of abrasion resistance The obtained polyester composition was made into a biaxially stretched film by the method shown in the examples, and a tape slit to a width of 1/2 inch was used as a metal pin (diameter 6 mm, surface roughness). Ra 0.045μ
m,) with a load of 100 g, a winding angle of 90 degrees, and a traveling speed of 3.0 cm / sec for 10 m, and the white shavings (white powder) adhering to the metal pin surface are visually ranked as follows. Grades 1 and 2 were accepted. Very small amount of white powder generated: 1st class Small amount of white powder generated: 2nd class Large amount of white powder generated: 3rd class Very large amount of white powder generated: 4th class

(4) Evaluation of surface irregularities The obtained polyester composition was made into a biaxially stretched film by a usual method, and a surfcom surface roughness meter according to JIS B0601 was used to measure a needle diameter of 2 μm, a load of 70 mg, and a measurement reference length of 0.
The center line average roughness (Ra) was measured under the conditions of 25 mm and a cutoff of 0.08 mm.

Example 1 B. E. T. 10 parts by weight of chi-type aluminum oxide particles having a specific surface area of 70 m ² / g and 90 parts by weight of ethylene glycol were mixed, and then dispersed using a sand mill at room temperature for 1.5 hours to obtain chi-type aluminum oxide particles / ethylene glycol. A slurry (A) was obtained.

On the other hand, 0.06 parts by weight of magnesium acetate as a catalyst was added to 100 parts by weight of dimethyl terephthalate and 64 parts by weight of ethylene glycol to carry out an ester exchange reaction, and then the slurry (A) 6 prepared above was used as a reaction product.
Parts by weight, 0.03 parts by weight of antimony trioxide as a catalyst, and 0.03 parts by weight of trimethyl phosphate as a heat-resistant stabilizer are added to carry out a polycondensation reaction to obtain a polyethylene terephthalate composition (Y) having an intrinsic viscosity of 0.625. It was The secondary particle diameter measured by a transmission electron microscope was 0.35 μm.

The polyethylene terephthalate composition (Y) was melted and extruded at 290 ° C., then stretched at 90 ° C. in the length and width directions by 3 times, and then at 220 ° C. for 15 minutes.
Heat treatment was performed for 2 seconds to obtain a polyethylene terephthalate biaxially stretched film having a thickness of 15 μm.

When this film was evaluated, Ra =
The film was 0.015 μm and had a wear resistance evaluation of grade 1, and the film was very excellent in wear resistance.

FIG. 1 shows the X-ray diffraction pattern of the chi-type aluminum oxide particles used in Example 1.

Examples 2 to 4 Biaxially stretched polyester films were obtained in the same manner as in Example 1 by changing the specific surface area, secondary particle diameter, addition amount, etc. of the chi-type aluminum oxide particles in the polyethylene terephthalate composition. It was The evaluation results of these films are shown in Table 1. It can be seen that these films have good abrasion resistance.

Example 5 A polyethylene terephthalate composition (X) was obtained in the same manner as in Example 1 except that aluminum oxide particles were not added.

The polyethylene terephthalate composition (Y) of Example 1 was melt-coextruded on (X) to obtain a laminated unstretched film. The extrusion temperature at this time was 290 ° C. After that, the film was stretched at 90 ° C. in the lengthwise and transverse directions three times, respectively, and further heat treated at 220 ° C. for 20 seconds to obtain a laminated biaxially stretched film.

The thickness of each of the layers (X) and (Y) is 1
It was 0 μm and 0.6 μm.

When this film was evaluated, as shown in Table 1, it was Ra = 0.015 μm, and the abrasion resistance was grade 1, and the film was very excellent in abrasion resistance.

Example 6 A polyethylene terephthalate composition (Z) was prepared in the same manner as in Example 1 except that 0.6 part by weight of styrene-divinylbenzene copolymer particles having an average particle size of 0.6 μm were added in place of the aluminum oxide particles. Got

After the polyethylene terephthalate composition (Y) of Example 1 and the above polyethylene terephthalate composition (Z) were chip-blended at a ratio of 1: 1, a polyethylene terephthalate biaxially stretched film was prepared in the same manner as in Example 1. Obtained.

When this film was evaluated, as shown in Table 2, it was Ra = 0.018 .mu.m, the abrasion resistance was grade 1, and the film was excellent in abrasion resistance.

[0045]

[Table 1]

[Table 2] Comparative Examples 1 to 5 Biaxially stretched polyester films were obtained in the same manner as in Example 1, except that the type of particles and the crystal structure of aluminum oxide particles were changed. The evaluation results of these films are shown in Table 3. These films were not satisfactory in abrasion resistance.

[0046]

[Table 3]

[0047]

INDUSTRIAL APPLICABILITY The polyester composition of the present invention contains aluminum oxide particles having a specific crystal structure, and when made into a film, it exhibits excellent abrasion resistance and is particularly suitable for magnetic tape applications.

[Brief description of drawings]

FIG. 1 shows an X-ray diffraction pattern of chi-type aluminum oxide particles used in Example 1.

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Claims (2)

[Claims] 1. A thermoplastic polyester composition containing chi-type aluminum oxide particles. 2. A thermoplastic polyester film containing chi-type aluminum oxide particles.