JPH0794598B2 - Polyester composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a polyester composition, and more specifically, to a porous inert inorganic fine particle having a porosity of 50% and an average particle diameter of 0.2 to 1.5 μ. The present invention relates to a polyester composition containing, which is useful for a magnetic tape.

2. Description of the Related Art Polyesters, especially polyethylene terephthalate, are widely used as fibers, films and other molded articles because of their excellent physical and chemical properties. However, contrary to its excellent characteristics, unfavorable troubles such as deterioration of workability and reduction of product value due to process passability in the molding process for obtaining the above-mentioned molded product or poor slipperiness in handling by the product itself occur. It is also known.

In response to these problems, a number of methods have been proposed in which fine particles are contained in polyester to impart appropriate unevenness to the surface of the molded product to improve the surface slipperiness of the molded product, some of which are in practical use. .

For example, as a means of improving the surface characteristics of polyester molded products, it is roughly classified to a method of precipitating a part or all of the catalyst used during polyester synthesis in the reaction step (internal particle precipitation method). It is known to add afterwards (external particle addition method).

However, since the internal particle deposition method of (3) increases the amount of fine particles, coarse particles are likely to be generated when the amount of the metal compound added is increased, and it is difficult to control the particle amount and particle size. have. On the other hand, the external particle addition method is advantageous in that it is easy to select the amount of particles and the particle size, and the fine particles are insoluble and inactive in the polyester, so that the polymer characteristics and particle state during long-term operation are stable. The particle type is a preferable class. However, such inactive inorganic fine particles do not have sufficient affinity with polyester and are liable to cause peeling at the interface when forming a yarn, a film, etc. When forming a yarn, the yarn breaks in the manufacturing process such as spinning and drawing. In addition, when the film is used, especially when it is used as a magnetic tape, it is a major cause of running abrasion. In recent years, these problems have become apparent from the viewpoints of higher quality requirements and improved productivity, and polymers capable of improving these problems are required.

OBJECT OF THE INVENTION The present inventors have conducted extensive studies to develop a polymer that solves the above-mentioned problems, and as a result, found that the objective can be achieved by incorporating inert inorganic fine particles having specific characteristics into the polyester. The invention was reached.

An object of the present invention is to provide a polyester composition capable of forming a film having improved running and abrasion resistance in which interfacial peeling between a polymer and fine particles hardly occurs.

According to the present invention, the porosity is 50%.
This is achieved by the polyester composition containing 0.01 to 3% by weight of porous inert inorganic fine particles having the above average particle diameter of 0.2 to 1.5 μm.

The polyester referred to in the present invention is not particularly limited as long as it can be melt-molded into a film, and examples thereof include polyethylene terephthalate, polytetramethylene terephthalate,
Preferable examples include poly-1,4-cyclohexylene dimethylene terephthalate and polyethylene-2,6-naphthalene dicarboxylate. Of course, these polyesters may be homopolyesters or copolyesters, and examples of the copolymerization component include diol components such as diethylene glycol, neopentyl glycol and polyalkylene glycol, adipic acid, sebacic acid and phthalic acid. , Diphthalic acid components such as isophthalic acid, 5-sodium sulfoisophthalic acid, trimellitic acid,
Examples include polyfunctional carboxylic acid components such as pyromellitic acid. Among these, polyester having ethylene terephthalate as a main repeating unit, particularly polyethylene terephthalate is preferable.

The polyester preferably has an intrinsic viscosity of 0.4 or more (solvent: orthochlorophenol, temperature: 35 ° C.).

In the present invention, the inert inorganic fine particles contained in the polyester have a porosity of 50% or more and are porous and have an average particle diameter of 0.
Inert inorganic fine particles of 2 to 1.5 μm. This "porosity" can be calculated from the specific gravity of fine particles and the pore volume. The porosity is preferably 70 to 90%.

The reason why the porous fine particles used in the present invention have a high affinity for polyester is not clear, but one reason is considered to be that the fine particles permeate the pores of the polyester. The average particle size is preferably 0.2 to 1.5 µ, and particularly preferably 0.3 to 1 µ. As the inorganic fine particles, those having a particle size adjusted to the above average particle size are used. About 10 for the particle size distribution of inert inorganic particles
It is more preferable that it contains almost no coarse particles of μ or more and has a sharp distribution on the fine side. Further, in the field of magnetic tapes for video tapes, which is the main application of polyester, it is preferable that the average particle size is 1 μm or less and that the fine distribution has a sharp distribution. Here, the "average particle diameter" means the "equivalent spherical diameter" of the particles at the point of 50% by weight of all the particles measured. By "equivalent spherical diameter" is meant the diameter of an imaginary sphere having the same volume as the particle and can be calculated from electron micrographs of the particle or measurements by conventional sedimentation methods.

Preferable examples of the porous inert inorganic particles include particles containing calcium silicate, silicon dioxide (silica), titanium oxide (titania), zirconium oxide (zirconia), aluminum oxide (alumina) and the like. The manufacturing method can be various manufacturing methods.
For example, in silica, a method in which sodium silicate or the like is hydrolyzed, solid primary particles are dispersed in water, and then colloidal particles are dried to form porous particles (silicate sol-gel method or wet method) , A method of vaporizing silicon chloride or the like and burning and decomposing it in an acid water flame (dry method). In titania, titanium alkoxide is hydrolyzed to form titanium hydrate gel, which is then dried and fired (titanium oxide method), and titanium chloride is burned and decomposed in an acid water flame (dry method).
Etc. Also, various methods such as a dry method can be used for zirconia and alumina. Then, the porosity of the particles can take a predetermined value by controlling each condition in such a manufacturing method.

The inert inorganic fine particles may be added to the polyester before the polymerization of the polyester is completed, and at any time and by any method, especially at the final stage of the transesterification reaction or the esterification reaction, especially immediately before the end of the reaction. It is preferable to add. The amount of the inert inorganic fine particles added to the polyester is preferably 0.01 to 3% by weight, more preferably
It is 0.1 to 2.5% by weight. When the addition amount is less than 0.01% by weight, the slipperiness of the polyester molded product tends to be insufficient, and when it exceeds 3% by weight, the surface irregularities of the polyester molded product, particularly the film, may become excessively rough, which is not desirable.

EXAMPLES The present invention will be described more specifically with reference to the following examples. In addition, the measurement of each characteristic value in the examples was performed by the following methods.

1) Porosity The pore volume (Vp) of the particles was determined by the mercury-helium method. That is, first, using a mercury porosimeter,
The specific volume (Vm) of the secondary particles, which is a value including pores, was measured under atmospheric pressure. Similarly, with a gas adsorption device (using helium), the specific volume (Vn) of the particles themselves (primary particles), which is the value excluding the pores, was measured from the dead volume measurement by the constant pressure volumetric method. Then, the pore volume (Vp) was obtained from the formula Vp = Vm−Vn.

Then, according to JIS-K0061, specific gravity bin (pycnometer)
The specific gravity of the particles themselves was measured by the method.

The porosity was calculated from the following formula from the pore volume and the specific gravity of the particles.

2) Intrinsic viscosity The polymer was dissolved in orthochlorophenol and the viscosity was measured from the solution viscosity measured at 35 ° C.

3) Calender scraping judgment The scraping property of the running surface of the base film was evaluated using a 5-stage mini super calendar. The calender was a five-stage calender consisting of a nylon roll and a steel roll. The processing temperature was 80 ° C, the linear pressure applied to the film was 200 kg / cm, and the film speed was 50 m / min. Running film is full length
The abrasion resistance of the base film was evaluated by the dirt attached to the top roller of the calender when it was run for 2000 m.

<Five-step judgment> ◎ Nylon roll has no dirt ○ Nylon roll has almost no dirt △ Nylon roll is dirty × Nylon roll is very dirty × × Nylon roll is heavily dirty 4) Scratch judgment base film is 1/2 inch wide Slit into the above (5)
Simultaneously with the measurement of the friction coefficient of the film, the film was applied to the fixed rod at an angle of 152 and the film was run for 10 m at a film speed of 20 cm / sec.
After repeating the number of times, the thickness, depth, and number of scratches on the surface of the 1 / 2-inch wide base film were comprehensively evaluated, and the following 5 levels were judged.

<5-level judgment> ◎ No scratches are found on the 1/2 inch width base film. ○ Scratches are hardly found on the 1/2 inch width base film. △ Scratches are found on the 1/2 inch width base film. Book)) Some thick scratches are found on a 1/2 inch width base film. Many thick and deep scratches are found on a × 1/2 inch width base film. 5) Film surface roughness (Ra) JIS B It measured according to 0601. Use a stylus surface roughness meter (SURFCOM3B) manufactured by Tokyo Seimitsu Co., Ltd.
A chart (film surface roughness curve) was drawn under the conditions of μ and load of 0.07 g. From the film surface roughness curve, a portion of the measurement length L is extracted in the direction of the center line, the center line of the extracted portion is the X axis, and the vertical magnification direction is the Y axis.
When the roughness curve is represented by Y = f (x), the value (Ra: μ) given by the following equation is defined as the film surface roughness.

In the present invention, 8 pieces were measured with a reference length of 0.25 mm, and Ra was expressed as an average value of 5 pieces excluding 3 pieces having the larger values.

Examples 1 to 8 Inorganic fine particles having 90 parts by weight of ethylene glycol (hereinafter abbreviated as EG) and having a porosity and an average particle diameter as shown in Table 1.
After adding 10 parts by weight, mixing and stirring were performed to obtain a slurry.

Silica (SiO ₂ ) is produced by the wet method,
Further, titania (TiO ₂ ) and zirconia (ZrO ₂ ) used were those produced by a dry method.

Further, 100 parts by weight of dimethyl terephthalate and 70 parts by weight of EG were used as a catalyst in the transesterification reaction using 0.035 parts by weight of manganese acetate tetrahydrate as a catalyst, and the above slurry was added under stirring in the amount shown in Table 1 during the reaction.

After the transesterification reaction, 0.03 parts by weight of trimethyl phosphate,
After adding 0.03 part by weight of antimony trioxide, polycondensation reaction was carried out in a usual manner under high temperature vacuum to obtain polyethylene terephthalate having an intrinsic viscosity of 0.62.

Furthermore, each polyester is chipped, dried at 180 ° C, sheeted at 295 ° C by an extruder, and then 95 ° C ~ 1
The film was biaxially stretched at a longitudinal stretching ratio of 3.0 times and a transverse stretching ratio of 3.5 times at 30 ° C., and further heat set at 200 ° C. to obtain a film having a thickness of 15 μ.

The characteristics of this film are shown in Table 1 and the quality of the film was good.

Comparative Examples 1 to 5 The same procedure as in Example 1 was conducted except that the inert inorganic fine particles having the porosity and the average particle diameter shown in Table 1 were used and the addition amount was set to the amount shown in Table 1. An axially stretched film was obtained.

The characteristics of this film are shown in Table 1. However, sufficient quality could not be obtained due to poor sharpness and coarseness for surface magnetic tape applications.

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide a polyester composition in which interfacial peeling between fine particles and a polymer is unlikely to occur during molding, the polyester composition has less trouble in the molding step, and has improved running sharpness. It has the advantage that films, especially magnetic tapes, can be produced.

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Claims (2)

[Claims] 1. A porosity of 50% or more and an average particle size of
Porous inert inorganic fine particles having a size of 0.2 to 1.5 μ are used in the range of 0.01 to 3
A polyester composition containing 100% by weight. 2. The polyester composition according to claim 1, wherein the polyester is a polyester containing ethylene terephthalate as a main repeating unit.