JPH10287800A - Polyester composition and film made therefrom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition being excellent in heat stability as a polymer and electrostatic application characteristic, giving a molding excellent in abrasion resistance and running performance and being excellent in productivity in film formation by adding a specified amount of aluminum silicate particles having a mean article diameter and an aluminum fraction in specified ranges to a polyester to form a composition which shows a specified resistance in a specified range when molten. SOLUTION: This composition contains 0.005-10 wt.% aluminum silicate particles having a means particle diameter of 0.001-3 μm and an aluminum fraction of 5-30 wt.% and shows a specific resistance of 1×10<7> to 5×10<8> Ω.cm when molten. It is desirable to use calcium carbonate or aluminum silicate particles in combination with the aluminum silicate particles. It is desirable that the calcium carbonate particles have a mean particle diameter larger than that of the aluminum silicate particles and are contained in an amount of 0.005-10 wt.% based on the composition. It is desirable that the aluminum oxide particles have a mean particle diameter of 0.001-0.5 μm and are contained in an amount of 0.01-3 wt.% based on the composition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polyester composition and a film comprising the same. More specifically, abrasion resistance, and a polyester composition suitable for obtaining a film having excellent running properties and productivity, and
It relates to a film comprising the same.

[0002]

2. Description of the Related Art In general, thermoplastic polyesters such as polyethylene terephthalate have excellent mechanical properties and are widely used as molded products such as films and fibers.

[0003] Usually, in order to impart lubricity to a molded article, the polyester is made to contain inert particles in the polyester to give irregularities on the surface of the molded article. This method is effective for improving running properties, but when applied to molded articles, especially films for magnetic tape, the abrasion resistance, scratch resistance and productivity do not reach satisfactory levels. Was.

If the molded article, for example, a magnetic tape film has low abrasion resistance, abrasion powder of the film is likely to be generated during the manufacturing process of the magnetic tape, and furthermore, a step of applying a magnetic layer. As a result, coating omission occurs, and as a result, omission (dropout) of magnetic recording occurs. In addition, when a magnetic tape is used, in many cases, the magnetic tape is run while being in contact with a recording / reproducing device. Drop-out). That is, the magnetic tape film needs to have running properties and abrasion resistance both during the manufacturing process of the magnetic tape and when used as a magnetic tape.

[0005] In order to solve these problems, a method of adding particles (external particle method) and a method of precipitating particles with catalyst residues (inner particle method) have been proposed. For example,
The former include JP-A-62-172031 (silicone particles), JP-A-5-3377 (spherical silica and calcium carbonate), JP-A-5-4412 (spherical silica), and JP-A-5-4413. Publication (spherical silica). However, these particles are suitable for forming a uniform surface, while PET
It has poor affinity with the drug, and often falls off, causing trouble. In addition, Japanese Patent Application Laid-Open No. 55-4511
No. 8 (aluminum silicate), JP-A-55-107
No. 495 (aluminum silicate), and the like, but the aluminum silicate described therein has an unstable particle shape, a large number of coarse particles in the particle size distribution, surface uniformity, and abrasion resistance. However, there is still room for improvement.

[0006] Further, the conventional polyester composition containing outer grains has a high productivity in forming a film, that is,
It cannot be said that the demand for an increase in the film forming speed has been sufficiently achieved, and higher productivity has been desired.

[0007] The inner grain method is disclosed in JP-A-34-51.
No. 44 (alkali metal salt) and JP-A-40-3291
JP (Telephthalate), JP-A-48-61556 (containing lithium element), JP-A-51-11286
No. 0 (containing a lithium element, a calcium element, and a phosphorus element) has been proposed, and these inner grains are known to form unique surface projections, but the surface projections are relatively soft. There is a need for improvement because it is easily damaged compared to the external grain method.

[0008] In recent years, the quality of film applications has been improved, and the development of film materials having higher functionality has been desired. However, conventional products are not always sufficient in running property and abrasion resistance. Is required.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and by incorporating specific particles into polyester, the thermal stability and electrostatic application characteristics of the polymer can be improved. It is an object of the present invention to provide a polyester composition which is excellent in abrasion resistance and running property at the time of molding and is excellent in productivity at the time of forming a film.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide an aluminum silicate particle having an average particle diameter of 0.001 to 3 μm and an aluminum fraction of 5 to 30% by weight. It is achieved by a polyester composition characterized by containing by weight and having a specific resistance at the time of melting in the range of 1 × 10 ^{7 to} 5 × 10 ⁸ Ω · cm.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester of the present invention is not particularly limited as long as it can form a film. Specifically, polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate,
Polyethylene-1,2-bis (2-chlorophenoxy)
Preference is given to ethane-4,4'-dicarboxylate.

These polyesters include, as copolymerization components, dicarboxylic acids such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, 4,4'-diphenyldicarboxylic acid and ester-forming derivatives thereof, polyethylene glycol, Copolymerize dioxy compounds such as diethylene glycol, hexamethylene glycol, polypropylene glycol and neopentyl glycol; oxycarboxylic acids such as p- (β-oxyethoxy) benzoic acid; and ester-forming derivatives thereof. However, the copolymerization amount is 20% based on all polyester repeating units.
It is preferably at most mol%.

The average particle size of the aluminum silicate particles in the present invention is from 0.001 to 3 μm, and from 0.01 to 2 μm.
μm is preferred. If the average particle size of the aluminum silicate particles exceeds 3 μm, the surface projections become too large and easily fall off during running. If the average particle size is smaller than 0.001 μm, sufficient projections cannot be obtained and the running property is reduced.

The content of the aluminum silicate particles with respect to the polymer is 0.005 to 10% by weight,
It is preferably about 5% by weight. 0.005 content
If the content is less than 1% by weight, the wear resistance is not sufficiently exhibited, and
When the content is more than 0% by weight, the particles are aggregated to form coarse particles, and the surface roughness of the film is remarkably reduced. The composition of the aluminum silicate particles in the present invention requires that the aluminum fraction be 5 to 30% by weight, and preferably 10 to 20% by weight. The aluminum fraction is less than 5% by weight,
If it exceeds 0% by weight, it becomes difficult to control the particle size during the particle generation process, the particle size distribution may be widened, the presence of coarse particles may increase, and the surface roughness of the film may be significantly reduced.

As a method for producing aluminum silicate particles in the present invention, for example, an alkali metal, ammonium or organic base silicate and an alkali-soluble aluminum compound are simultaneously added to an aqueous alkali solution having a pH of 10 or more. The target particles can be generated by the reaction. The aluminum silicate particles of the present invention are particles made of a composite oxide containing an alkali metal atom such as a sodium atom in addition to an aluminum atom and a silicon atom, and have an amorphous crystalline form. Also,
The shape of the particles is preferably spherical, and the ratio of the major axis / minor axis of the particles is preferably 1.0 to 1.2.

Such aluminum silicate particles can be used as an anionic surfactant such as sodium dodecylbenzenesulfonate, sodium lauryl sulfate and formalin condensate of naphthalenesulfonic acid, and polyoxyalkylene as long as the effects of the present invention are not impaired. Nonylphenol ether,
Nonionic surfactants such as polyethylene glycol monostearate, water-soluble synthetic polymers such as polyvinyl alcohol, polyvinylpyrrolidone, and polyethylene glycol; water-soluble natural polymers such as gelatin and starch; And those surface-treated with a titanium-based coupling agent, phosphoric acid, phosphorous acid, phosphonic acid, a derivative thereof, or the like can be used.

Further, in the composition of the present invention, it is preferable to use calcium carbonate particles or aluminum oxide particles in combination as particles other than the aluminum silicate particles. The average particle size of the calcium carbonate particles is preferably larger than that of the aluminum silicate particles, and the content is preferably 0.005 to 10% by weight. The average particle size of the aluminum oxide particles is 0.001 to 0.
5 μm is preferable, and the content is 0.01 to 3% by weight.
It is preferred that The type of the calcium carbonate particles is not particularly limited, but preferably has a calcite structure obtained by a synthesis reaction between an aqueous solution of calcium hydroxide and carbon dioxide. As the shape of the calcium carbonate particles, those having a spherical shape, a cubic shape, a polyhedral shape, or the like are used, but are not particularly limited.

The crystal form of the aluminum oxide particles is not particularly limited, but preferably has one or more crystal forms selected from δ, γ, and θ types.
Examples of the method for producing such aluminum oxide particles include a high-temperature gas-phase hydrolysis method in which flame is hydrolyzed using anhydrous aluminum chloride as a raw material, and an alumina hydrate obtained by hydrolyzing high-purity alkyl aluminum or aluminum alkoxide. A method of hydrolyzing the organic aluminum salt to be calcined may be mentioned, but is not particularly limited.

The composition of the present invention contains inorganic particles such as silica, kaolinite, talc, and titanium dioxide, as well as crosslinked polystyrene, polyimide, polymethyl methacrylate, and formaldehyde resin as long as the effects of the present invention are not impaired. And organic polymer particles such as a phenol resin and a silicone resin, and internal particles precipitated by a reaction mainly involving a catalyst residue in a polyester polycondensation reaction internal system.

In mixing the aluminum silicate particles into the polyester of the present invention, besides a method of directly adding the particles to the polymerization reaction system of the polyester, for example, a method of kneading the particles into a molten polyester is also possible. The timing of addition to the former polymerization reaction system is optional, but is preferably before the transesterification reaction or after the transesterification reaction and before the start of the polycondensation reaction under reduced pressure. In the case of the latter kneading, a method of directly kneading the particles or a method of kneading directly while reducing the pressure in a slurry state may be used.

The polyester composition of the present invention must further have a specific resistance of 1 × 10 ^{7 to} 5 × 10 ⁸ Ω · cm when melted, and 1 × 10 ⁷ to 2 × 10 ⁸ Ω · cm. The range of cm is preferred. Specific resistance at the time of melting is 1 × 10 ⁷ Ω · cm
If the amount is less than the above, when the polyester composition is recovered and used, the thermal stability of the polymer becomes poor and the film cannot be stably formed. On the other hand, when the specific resistance at the time of melting exceeds 5 × 10 ⁸ Ω · cm, it becomes difficult to increase the film forming rate during the production of the film using the electrostatic application cooling method, and the productivity of the film is extremely deteriorated.

The polyester composition of the present invention is suitable for a film, particularly a film for a magnetic recording medium such as a magnetic tape, and can be formed into a film by the following method, for example.

After the polyester composition pellets are sufficiently dried, they are immediately supplied to an extruder. Put these pellets in 2
Melted at 60-350 ° C, extruded from a die in sheet form,
It is cooled and solidified on a casting roll to obtain an unstretched film. Next, the unstretched film is preferably biaxially stretched. As the stretching method, a sequential biaxial stretching method, a simultaneous biaxial stretching method, a method of stretching the film thus biaxially stretched again, or the like may be used. Although it depends on the composition of the polyester, for example, in order to obtain a sufficient elastic modulus as a film for a magnetic recording medium, it is preferable that the final stretch area magnification (longitudinal magnification × lateral magnification) is 6 or more.

Further, in order to keep the heat shrinkage of the film small, it is preferable to perform a heat treatment at a temperature of 150 to 260 ° C. for about 10 to 60 seconds.

The film obtained from the polyester composition of the present invention can be used as a single-layer film or as a laminated film. In the case of a laminated film, it is preferable to use the polyester of the present invention as a film constituting at least one layer, because the abrasion resistance and running property of the film surface are improved. Furthermore, it is preferable that the film containing aluminum silicate is one of the outermost layers of the laminated film from the viewpoints of running properties and dubbing properties. As a method for laminating the films, known methods such as melt coextrusion can be used.

For example, when aluminum silicate particles are used in combination with calcium carbonate particles and aluminum oxide particles, each of the particles may be contained in a different layer. It is preferable that the aluminum particles, the calcium carbonate particles, and the aluminum oxide particles are contained in the same outermost layer on at least one side. At this time, the thickness t of the film layer containing the aluminum silicate particles is preferably 0.2 d ≦ t ≦ 10 d, more preferably 0.1 d, in relation to the average particle diameter d of the aluminum silicate particles. 5d ≦ t ≦ 5d, especially 0.5
It is preferable that d ≦ t ≦ 3d.

[0027]

The present invention will be described in detail below with reference to examples. The method for measuring each characteristic used in the present invention is as follows.

(1) Average particle size of particles such as aluminum silicate The average particle size was measured using LA700 manufactured by Horiba, Ltd.

(2) Alumina fraction of aluminum silicate Measured by X-ray fluorescence analysis.

(3) Specific Resistance of Polyester upon Melting British Journal of Upright Physics (Brit. J. Appl. Phys) Vol. 17, No. 1149-
The method described on page 1154 (1996) was followed. However, in this case, the temperature at the time of melting the polymer composition was 280 ° C., and the value immediately after the application of 5000 V DC was taken as the specific resistance at the time of melting.

(4) Film Properties (A) Surface Roughness Ra (μm) According to JIS B-0601, using a Surfcom surface roughness meter, needle diameter 2 μm, load 70 mg, measurement reference length 0.25
mm, the center line average roughness measured under the condition of cutoff 0.08 mm was adopted. (B) Evaluation of abrasion resistance The obtained polyester composition was formed into a biaxially stretched film by the method described in Examples, and a tape-shaped roll slit into a narrow width was used as a guide roll made of stainless steel SUS-304. 200
g / 1/2 inch constant tension (200 g / 1/2 inch)
ch), at a high speed (250 m / min), rubbing 200 m in length, and ranked as follows according to the amount of white powder generated on the surface of the guide roll.

First-class: No white powder is generated at all. Second-class: White powder is slightly generated. Third-class: White powder is generated slightly more. Class 4: White powder is generated. Example 1 10 parts by weight of aluminum silicate particles having an average particle diameter of 0.2 μm and an aluminum fraction of 20% by weight, ethylene glycol
90 parts by weight of a mixture of the same and stirred at room temperature for 3 hours with a dissolver to obtain ethylene glycol of aluminum silicate particles.
Ruslurry (A) was obtained.

10 parts by weight of δ-type aluminum oxide (alumina) particles having an average particle diameter of 0.1 μm, ethylene glycol 9
0 parts by weight were mixed and subjected to a dispersion treatment using a sand grinder to obtain ethylene glycol slurry (B) of δ-type aluminum oxide particles.

20 parts by weight of calcium carbonate particles having an average particle diameter of 0.7 μm and 80 parts by weight of ethylene glycol are mixed and dispersed using a sand grinder to obtain an ethylene glycol slurry (C) of calcium carbonate particles. I got

On the other hand, after a transesterification reaction was carried out by adding manganese acetate as a catalyst to dimethyl terephthalate and ethylene glycol, the slurry (A) and the slurry (B) previously prepared were added to the reaction product. , Slurry (C), antimony trioxide as a catalyst and trimethyl phosphate as a heat stabilizer were added, and a polycondensation reaction was carried out to obtain polyethylene terephthalate. The specific resistance of the obtained polymer at the time of melting was 7 × 10 ⁷ Ω · cm.

The polyethylene terephthalate composition was melt-extruded at 290 ° C., then stretched three times vertically and horizontally at 90 ° C., and then heat-treated at 220 ° C. for 15 seconds.
A polyethylene terephthalate biaxially stretched film having a thickness of 15 μm was obtained.

At this time, the maximum rotation speed of the cooling drum by the electrostatic application cooling method could be as high as 55 m / min, and the productivity of the film was good.

When this film was evaluated, Ra =
The film was 0.015 μm, having a first grade of abrasion resistance evaluation, and was a film excellent in abrasion resistance.

Examples 2 to 5 Biaxial stretching was carried out in the same manner as in Example 1 except that the particle size, aluminum (Al) fraction, and amount of added aluminum silicate particles in the polyethylene terephthalate composition were changed. A polyester film was obtained. Table 1 shows the evaluation results of these films. The abrasion resistance of these films was very good. Also, the specific resistance of the polymer at the time of melting is good,
The productivity during film formation was good.

Example 6 A polyethylene terephthalate composition (X) was obtained in exactly the same manner as in Example 1 except that only two kinds of particles, aluminum silicate and calcium carbonate, were added. further,
A polyethylene terephthalate composition (Y) was obtained in exactly the same manner as in Example 1 except that only two kinds of particles, aluminum silicate and aluminum oxide (alumina), were added. This (Y) was melt-coextruded onto (X) to obtain a laminated unstretched film. The extrusion temperature at this time is 290 ° C
And After that, it is stretched three times vertically and horizontally at 90 ° C,
Thereafter, heat treatment was performed at 220 ° C. for 20 seconds to obtain a laminated biaxially stretched polyester film. The composition of the particles of the film is shown in Table 1.

Each of the layers (X) and (Y) has a thickness of 8
μm and 0.5 μm. When this film was evaluated, as shown in Table 1, it was Ra = 0.016 μm, and the film had a first-class abrasion resistance evaluation, and was a film having extremely excellent abrasion resistance.

Comparative Examples 1 to 3 Biaxially stretched polyester films were obtained in the same manner as in Example 1 except that the particle type, particle diameter, particle content and aluminum fraction were changed. Table 2 shows the evaluation results of these films. These films were not films with satisfactory abrasion resistance. Further, the specific resistance of these polymers at the time of melting was poor, and the productivity at the time of film formation was not good.

[0043]

[Table 1]

[Table 2]

[0044]

The polyester composition of the present invention, when formed into a film, has excellent abrasion resistance and running properties and is suitable for use in magnetic recording media. Further, the electrostatic application characteristics are good, and the productivity during film formation can be improved.

Claims (4)

[Claims] An average particle size is 0.001 to 3 μm,
It contains 0.005 to 10% by weight of aluminum silicate particles having an aluminum fraction of 5 to 30% by weight, and has a specific resistance of 1 × 10 ^{7 to} 5 × 10 ⁸ Ω · cm at the time of melting. A polyester composition comprising: 2. The polyester composition according to claim 1, which contains 0.005 to 10% by weight of calcium carbonate particles having an average particle size larger than that of the aluminum silicate particles. 3. The polyester composition according to claim 1, comprising 0.01 to 3% by weight of aluminum oxide particles having an average particle size of 0.001 to 0.5 μm. 4. A film comprising the polyester composition according to claim 1, 2 or 3.