JP3277587B2 - Thermoplastic polyester composition and film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a thermoplastic polyester composition and a film comprising the same. More specifically, the present invention relates to a thermoplastic polyester composition suitable for obtaining a film having excellent abrasion resistance for a magnetic recording medium and the like, and 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 articles such as films.
Usually, in order to impart lubricity to a molded article, the polyester contains inactive particles in the polyester to give irregularities on the surface of the molded article. Although there are various types of such inert particles, generally, the inert particles have a problem that they lack affinity for the polyester and are inferior in abrasion resistance.

In order to solve this problem, studies have been made on surface treatment of inert particles.
JP-A-3-221158, JP-A-63-280763 (modifying the surface of colloidal silica particles with a glycol group), and JP-A-63-321345 (modifying the surface of colloidal silica particles with a coupling agent) And JP-A-62-235353 (surface treatment of calcium carbonate particles with a phosphorus compound) and the like have been proposed.

[0004] However, even in the case of using such a known method, when particles are repeatedly used by friction like a magnetic tape, particles are dropped off. For this reason, the use of special particles has recently been proposed, for example,
JP-A-62-172031 (silicone particles),
Japanese Patent Application Laid-Open No. 2-129230 (delta-type aluminum oxide particles) has been proposed, but is 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 which aluminum oxide particles containing a Group VIII element of the periodic table are mixed with a thermoplastic polyester. It is an object of the present invention to provide a composition capable of obtaining a film having excellent abrasion resistance when formed into a film, and a film comprising the composition.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to provide a thermoplastic polyester (A) and the element VI of the Periodic Table of the Elements.
This is achieved by a thermoplastic polyester composition characterized by comprising a group II element-containing aluminum oxide particle (B) and a film thereof.

The aluminum oxide particles (B) of the present invention contain a Group VIII element of the periodic table.
The content is preferably 0.0001% by weight to 5% by weight, more preferably 0.001% by weight to 1% by weight.

The periodic table of elements is roughly classified into a long-period type and a short-period type, and the periodic table of elements in the present invention is of a long-period type.
Specific examples thereof include o, Ni, Ru, Rh, Pd, Os, Ir, and Pt.

These elements contained in the aluminum oxide particles (B) may be present singly or in combination, but are preferably selected from Fe, Co and Ni elements.

When the aluminum oxide particles (B) containing a Group VIII element are blended with the polyester, the abrasion resistance when formed into a film is extremely excellent. This is because the presence of the Group VIII element makes the affinity with the polyester better.

The aluminum oxide particles (B) of the present invention are:
It can be obtained by a method such as firing aluminum hydroxide or firing alum, and can be obtained by containing or adding a Group VIII element or a Group VIII element compound to these raw materials.

The crystals of aluminum oxide particles have α, γ,
Although various crystal structures such as δ, θ, η, and 知 are known, at least one selected from α, γ, δ, and θ types of the aluminum oxide particles (B) of the present invention has a good affinity for polyester. Therefore, a mixture of crystals such as θ + α may be used.

The crystal structure of the aluminum oxide particles can be identified by a diffraction angle 2θ value at which a diffracted X-ray appears in the X-ray diffraction method. For this purpose, for example, JCPDS (Join) is used.
t Committee on Powder Diffraction Standards) data can be used.

The aluminum oxide particles (B) of the present invention are preferably fine, and the specific surface area of the aluminum oxide is preferably at least 10 m ² / g, more preferably at least 30 m ² / g.

[0015] Such particles usually cause agglomeration in polyester, but the secondary particle size can be arbitrarily selected according to the purpose of the film obtained by molding from the thermoplastic polyester composition. However, if it is too large, coarse projections will occur on the film surface,
Preferably 2.0 μm or less, more preferably 0.5 μm
m or less. Further, the thickness is preferably 0.01 μm or more. Here, the secondary particle diameter is an average circle-equivalent diameter when 1,000 particles are observed with a transmission electron microscope.

The amount of the aluminum oxide particles (B) to be added is 0.1 to 100 parts by weight of the thermoplastic polyester.
It is preferably from 01 to 30 parts by weight, more preferably from 0.1 to 10 parts by weight.

The thermoplastic polyester (A) in the present invention may be any one which can form a film. Examples thereof include polyethylene terephthalate, polytetramethylene terephthalate, polycyclohexylene dimethylene terephthalate, and polyethylene-terephthalate.
2,6-Naphthalenedicarboxylate 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, it can be obtained by a production method in which aluminum oxide particles are mixed and stirred using glycol, which is a starting material for polyester, as a solvent to form a dispersion slurry, and added to a thermoplastic polyester reaction system. The processing method at this time may be, for example, an ultrasonic wave or the like without using stirring, or a medium-type mill such as a sand grinder may be used.

For the incorporation into the polyester, in addition to the above-mentioned method of directly adding to the polymerization reaction system, for example, a method of kneading aluminum oxide particles into a molten polyester is also possible. The timing of addition to the former polymerization reaction system is optional, but is preferably from before the transesterification reaction to before the start of the pressure reduction in the polycondensation reaction. In the case of the latter kneading, a method of drying and kneading the particles into polyester or a method of directly kneading while reducing the pressure in a slurry state may be used.

The polyester film of the present invention can be produced, for example, by the following method. After the polyester pellets obtained by the polymerization reaction are sufficiently dried, they are immediately supplied to an extruder. 260
Melt at ~ 350 ° C, extrude into a sheet from a die, cool and solidify 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. Depending on the composition of the polyester, in order to obtain a sufficient elastic modulus as a film for a magnetic recording medium, the final stretch area magnification (longitudinal magnification ×
(Lateral magnification) is preferably 6 times or more. Further, in order to keep the heat shrinkage of the film small, it is preferable to perform a heat treatment for about 0.1 to 60 seconds in a temperature range of 150 to 260 ° C.

The film of the present invention can be used as a single-layer film or as a laminated film. In the case of a laminated film, at least one layer (hereinafter, also referred to as a laminated portion) made of the thermoplastic polyester composition of the present invention is disposed. The use of the laminated film of the present invention is preferable because the abrasion resistance, uniformity, and lubricity of the film surface are improved.

The position of the laminated portion constituting the laminated film of the present invention may be any position depending on the application, but it is preferable that the laminated portion constitutes at least one surface of the film. Further, a layer such as a coating may be present on such a surface.

The thickness of the laminated portion constituting the laminated film of the present invention should be 0.1 to 20 times the secondary particle diameter of the aluminum oxide particles (B) contained, so that the uniformity of the film surface can be improved. The slipperiness is particularly good, which is preferable.

The content of the aluminum oxide particles (B) in the laminated portion is preferably 0.05 to 30 parts by weight, more preferably 0.1 to 30 parts by weight, based on 100 parts by weight of the thermoplastic polyester.
-10 parts by weight is preferred.

When traveling properties are required, it is preferable to use inorganic or organic particles other than aluminum oxide in combination. Examples of such particles include inorganic particles such as calcium carbonate, titanium oxide, silicon oxide, calcium phosphate, and zirconium oxide, silicone resin, styrene-divinylbenzene copolymer, styrene-ethylvinylbenzene-divinylbenzene copolymer, and ethylvinyl. Crosslinked polymer particles such as a benzene-divinylbenzene copolymer may be mentioned, and so-called internal particles formed from a catalyst at the time of polyester polymerization may be used.

[0028]

Next, the present invention will be described based on Examples and Comparative Examples.
This will be described in more detail. Parts in Examples and Comparative Examples indicate parts by weight.

(1) No. VII in aluminum oxide particles
Determination of Group I Elements X-ray fluorescence and atomic absorption were used together. In the fluorescent X-ray method,
The measurement was performed after the aluminum oxide particles were press-molded.
In the atomic absorption method, aluminum oxide particles were heated and melted with boric acid and sodium carbonate, dissolved in hot nitric acid water, heated, and a sample was obtained and measured.

(2) Measurement of Specific Surface Area of Aluminum Oxide Particles Measurement was performed using Quantasorb manufactured by Yuasa Ionics Co., Ltd. In the measurement method, first, N ₂ is degassed by holding the sample particles at 200 ° C. under vacuum for 1 hour. Then, the N ₂ adsorption amount at liquid nitrogen temperature (-195.8 ° C.) was measured using a mixed gas of N _2, the He, obtain an adsorption isotherm by changing the mixing ratio of N _2, the He, the BET The specific surface area was calculated by the formula.

(3) Evaluation of Secondary Particle Diameter of Aluminum Oxide Particles Aluminum oxide particles are mixed with polyester,
After cutting into an ultra-thin section having a thickness of 0.2 μm, the section was observed with a transmission electron microscope, and evaluated by a circle-equivalent average diameter (μm) of 1000 aggregated secondary particles.

(4) Evaluation of Crystal Structure of Aluminum Oxide Particles The aluminum oxide particles were analyzed by an X-ray diffraction method. In order to identify the crystal structure of aluminum oxide in the polymer or the molded body, the polymer may be dissolved in a solvent, and aluminum oxide particles taken out by centrifugation or filtration may be measured by the same method. If the polymer is attached to the extracted particles, it is difficult to analyze by X-ray diffraction, so after extracting the particles from the polymer, washing with a suitable solvent that dissolves the polymer is repeated, and the particles are attached around the particles. It is important to remove the polymer that is present. The value of 2θ in various crystal structures is determined by JCPDS (Joint Committee on Powder D).
Iffraction Standards) No. registered as shown in Table 1 were used.

[0033]

[Table 1]

In the case where a plurality of crystal structures are mixed, the type of the mixed crystal structures is first determined from the X-ray diffraction. The changed X-ray diffraction was taken to determine which mixing ratio the target particles corresponded to by using this as a standard of the mixed product.

(5) Thickness of Laminated Portion The laminated film was cut into ultrathin sections so that the cross-sectional direction could be observed, and observed with a transmission electron microscope. And the thickness was measured.

(6) Evaluation of abrasion resistance The obtained thermoplastic polyester composition was formed into a film by the method described in Examples, and the film was slit into １ ／ inch, and a tape running tester TBT-300 [ ) Manufactured by Yokohama System Research Institute], and repeatedly run 1000 times in an atmosphere of 20 ° C. and 60% RH, and visually determine white shavings (white powder) attached to the guide portion. Here, the guide diameter is 8 mmφ, and the guide material is SUS2
7 (surface roughness 0.2 S), wrap angle 180 °, tape running speed 3.3 cm / sec. The evaluation criteria are as follows. Of these, the second grade or higher was accepted. Grade 1: Very low white powder generation. Class 2: Low white powder generation. Third grade: White powder generation amount is slightly large. Grade 4: Very large white powder generation.

(7) Evaluation of Surface Irregularities The obtained thermoplastic polyester composition was formed into a film by the method shown in Examples, and a needle diameter: 2 μm, load: 70 mg, using a Surfcom surface roughness meter according to JIS B0601.
Measurement reference length; 0.25 mm, cutoff; 0.08 mm
, The center line average roughness (Ra) was measured.

(8) Evaluation of Film Runnability The obtained thermoplastic polyester composition was formed into a film by the method shown in Examples, and the film was slit into a tape having a width of 1/2 inch. -7
Use Type 00 [Yokohama System Laboratory Co., Ltd.]
The film was run in an atmosphere of 60 ° C. and 60% RH, and the initial coefficient of friction was determined by the following equation (the film width was イ ン チ inch). μ _k = 2 / πln (T ₂ / T ₁ ) where T ₁ is the entrance tension and T ₂ is the exit tension. The guide diameter is 6 mmφ, the guide material is SUS27 (surface roughness 0.2S), the winding angle is 90 °, and the running speed is 3.
3 cm / sec. The coefficient of friction when mu _k obtained by this measurement is 0.3 or less: good, if more than 0.3 friction coefficient: it is determined that the failure. The mu _k is a magnetic recording medium film, the capacitor is a critical point affects the handling property at the time of processing such as packaging.

(9) Uniformity of protrusion height A scanning electron microscope with two detectors [ESM-3200,
Elionix Co., Ltd.] and a cross section measuring device [PMS-1,
Elionix Co., Ltd.], a projection height measurement value when scanning was performed with the height of the flat surface of the film surface set to 0, and an image processing apparatus [IBAS2000, Carl Zeiss Co., Ltd.]
To reconstruct a projection image of the film surface on the image processing apparatus. Next, a circle-equivalent diameter was obtained from the area of each projection obtained by binarizing the projection part with this surface projection image,
This is defined as the average diameter of the projection. The highest value among the binarized individual projections is defined as the height of the projection, and this is determined for each individual projection. This measurement is repeated 500 times at different locations, and the average height and standard deviation (S) of the measured projections are obtained, and the relative standard deviation is calculated by the following equation. RS = S / h RS: Relative standard deviation S: Standard deviation h: Average protrusion height The smaller the number, the more uniform the relative standard deviation.

Example 1 Ni element containing 0.1% by weight and specific surface area of 75 m ² /
g, 10 parts of aluminum oxide particles as a θ-type crystal and 90 parts of ethylene glycol were mixed, and then dispersed at room temperature for 1 hour using a sand grinder to obtain aluminum oxide particles / ethylene glycol slurry (X). On the other hand,
10 parts of calcium carbonate particles, ethylene glycol 90
After mixing, the mixture was dispersed at room temperature for 1 hour using a sand grinder to obtain a calcium carbonate particle / ethylene glycol slurry (Y).

On the other hand, 100 parts of dimethyl terephthalate,
After performing transesterification by adding 0.06 part of magnesium acetate and 0.03 part of antimony trioxide as a catalyst to 64 parts of ethylene glycol, the reaction product was heat-stabilized to 5 parts of the previously prepared slurry (X). A polycondensation reaction is performed by adding 0.03 part of trimethyl phosphate as an agent,
A polyethylene terephthalate composition (A) was obtained. Observation with an electron microscope revealed that the secondary particle size was 0.2 μm.

Polyethylene terephthalate composition (B)
Was obtained by exactly the same method except that 6 parts of the slurry (Y) was used instead of the slurry (X). Observation with an electron microscope showed that the average particle size of the calcium carbonate particles was 0.5 μm.

After mixing the above polyester compositions A and B at a ratio of 1: 1 respectively, the mixture was dried at 180 ° C. for 8 hours under reduced pressure (3T
orr), melt and extrude at 290 ° C.
Stretched three times vertically and horizontally at 0 ° C, and then 220 ° C
For 15 seconds to obtain a biaxially stretched polyethylene terephthalate film having a thickness of 15 μm.

When this film was evaluated, Ra;
0.012 μm, μ _k ; 0.25, abrasion resistance: second class, uniformity of projections: 1.0, and an excellent film.

Example 2 As aluminum oxide particles, Fe: 0.05%, C
o; a polyester composition (A) was obtained in the same manner as in Example 1 by using 0.02%, specific surface area: 100 m ² / g, and crystal type γ-type particles. On the other hand, a polyester composition (B) was obtained in the same manner as in Example 1 using silica particles.

The above master pellets were mixed at a ratio of 1: 1.
And the polyester composition B containing silica particles were dried under reduced pressure at 180 ° C. for 8 hours (3To).
rr), and then supplied to an extruder 1 and an extruder 2 (for example, a vented twin-screw kneading extruder).
And dissolved. After each of the two polymers is subjected to high-precision filtration, the polyester composition B containing silica in the intermediate layer portion and the particle-containing polymer in the double-sided surface layer lamination portion are formed in a three-layer merging block having a rectangular lamination portion. After being extruded in a sheet form from a fishtail-type die, stretched three times vertically and horizontally at 90 ° C, and then heat-treated at 220 ° C for 15 seconds, and then biaxially stretched polyethylene terephthalate having a thickness of 15μ. A film was obtained.

When this film was evaluated, the thickness of the laminated portion: 1.0 μm, Ra: 0.015 μm, μ _k ;
2. A very excellent film having abrasion resistance of 1st grade and uniformity of projections of 0.7.

Examples 3 to 5 The same method as in Examples 1 and 2 except that the kind and amount of the Group VIII element contained in the aluminum oxide particles, the crystal form and the specific surface area were changed, and the combined particles and the film structure were changed. To obtain a film. The results are shown in Tables 2 and 3. Thus, those within the scope of the present invention were excellent films.

Comparative Examples 1 to 7 Films were prepared in the same manner as in Examples 1 and 2 except that the kind and amount of the elements contained in the aluminum oxide particles, the crystal form and the specific surface area were changed, and the combined particles and the film structure were changed. I got The results are shown in Tables 3 and 4. The abrasion resistance of these films outside the scope of the invention was unsatisfactory.

[0050]

[Table 2]

[Table 3]

[Table 4]

[0051]

The polyester composition using the aluminum oxide particles containing a Group VIII element of the present invention can provide a film having excellent abrasion resistance. Further, the film of the present invention is excellent in abrasion resistance, so that it is suitably used particularly as a magnetic recording medium base which is repeatedly used.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08L 67/00-67/03

Claims (4)

(57) [Claims] 1. A thermoplastic polyester composition comprising a thermoplastic polyester (A) and aluminum oxide particles (B) containing a Group VIII element of the periodic table. 2. The thermoplastic polyester composition according to claim 1, wherein the crystal structure of the aluminum oxide particles (B) is at least one selected from α, γ, δ, and θ. 3. A biaxially oriented polyester film comprising the thermoplastic polyester composition according to claim 1. 4. A laminated polyester film for a magnetic recording medium base comprising at least one layer comprising the thermoplastic polyester composition according to claim 1 or 2.