JPH06114920A - Polyester composition - Google Patents

Abstract

PURPOSE:To provide a polyester composition having excellent wear resistance and scuff resistance. CONSTITUTION:Polyester composition comprises alumina particles each having mean particle size of 0.01-0.5mum at a ratio of 0.05-5wt.%, wherein the particles are at least one type selected from a group consisting of alpha-alumina, gamma-alumina and delta-alumina, the particles are surface-treated with alkaline metal hydroxide compound and the compound is used at a ratio of 0.05-1.0wt.% in terms of alkaline metal atom to the particles.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester composition having an excellent surface morphology and capable of forming a film having excellent slipperiness, abrasion resistance and scratch resistance.

[0002]

Polyesters, especially polyethylene terephthalate, have excellent physical and chemical properties,
It is widely used as a fiber, film, and other molded products. When polyester is used for a film, the slipperiness and scratch resistance of the film are important factors that affect the workability of the film manufacturing process and the processing process and the quality of the product.

In particular, when a magnetic layer is coated on the surface of a polyester film and used as a magnetic tape, significant friction occurs between the coating roll and the film surface when the magnetic layer is coated, and even after processing into a cassette tape. There has been a problem that significant friction and wear also occur with many guide parts and magnetic heads, which causes abrasion of the polyester surface and the like, resulting in loss of magnetic recording signals.

In order to improve the slipperiness and abrasion resistance of the film, there is a method of reducing the contact area between the film and the guide roll by giving unevenness to the film surface. A method of depositing inactive particles from the residue of the catalyst and a method of adding inactive inorganic particles are known. However, these particles have a problem that the larger the particle size is, the greater the effect of improving the lubricity, but on the other hand, the electromagnetic conversion characteristics are deteriorated, and the particles are easily removed due to abrasion, resulting in a loss of a magnetic recording signal.

Recently, as the speed of the magnetic tape manufacturing process has been increased, there has been a demand for a film having more excellent abrasion resistance in the calendar processing process during the magnetic tape manufacturing process. The calendering step is a step of forming a magnetic layer by coating and drying the magnetic layer composition on a polyester film, and then smoothing the surface of the magnetic layer. In this calendering process, since this film passes between the calender rolls to which extremely high pressure is applied, the projections on the surface of the film formed mainly by the inert inorganic particles are scraped off and abrasion powder is generated. When such abrasion powder adheres to the surface of the calendar roll, the surface of the magnetic layer of the film becomes rough, resulting in deterioration of the electrical characteristics of the resulting magnetic tape. When a film having poor abrasion resistance is used as a magnetic tape, abrasion powder is also generated in the running system in the tape deck, resulting in deterioration of electrical characteristics of the magnetic tape and loss of signal.

For the purpose of solving the above-mentioned problems, a method of adding inactive inorganic fine particles having an average particle diameter of 0.3 μm or less, particularly ultrafine particles of alumina, to a polyester is generally known. However, when such fine particles are added to polyester, the particles agglomerate and coarse projections are formed on the film surface, which causes problems such as deterioration of electromagnetic conversion characteristics. There is a challenge to improve.

[0007]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned conventional problems, and its purpose is to:
It is intended to provide a polyester composition capable of forming a film having excellent slipperiness, abrasion resistance and scratch resistance.

[0008]

As a result of intensive studies to overcome the above problems, the present inventors have found that α, γ or δ alumina particles having a specific particle diameter can be treated with an alkali metal hydroxide compound. In the polyester composition obtained by surface-treating and adding the treated alumina particles, the number of coarse particles due to the aggregation of alumina particles is small, and the biaxially stretched film formed from this composition has coarse projections. It has been found that the amount is small and the abrasion resistance and the abrasion resistance are excellent.

The polyester composition of the present invention contains alumina particles having an average particle diameter of 0.01 to 0.5 μm in a proportion of 0.05 to 5% by weight, the alumina particles being α-alumina, γ-alumina and δ-alumina. It is at least one selected from the group consisting of alumina, the alumina particles are surface-treated with an alkali metal hydroxide compound, and the alkali metal hydroxide compound is from 0.05 to 0.05 in terms of alkali metal atom with respect to the alumina. It is used in a proportion of 1.0% by weight, which achieves the object of the invention.

In a preferred embodiment, the alkali metal hydroxide compound is sodium hydroxide.

The present invention will be described in more detail below.

The polyester used in the present invention is a crystalline polyester such as polyalkylene terephthalate or polyalkylene naphthalate. The type thereof is not particularly limited, but polyethylene retephthalate (PET) in which the acid component is terephthalic acid and the glycol component is ethylene glycol is particularly suitable. PET in which other components are copolymerized can also be suitably used as long as the effects of the present invention are not impaired.

As acid components other than terephthalic acid,
Isophthalic acid, p-β-oxyethoxybenzoic acid, 2,
Examples of dicarboxylic acids include 6-naphthalenedicarboxylic acid, 4,4-dicarboxybenzophenone, bis (4-carboxyphenyl) ethane, adipic acid, sebacic acid, 5-sodium sulfoisophthalic acid, and cyclohexane-1,4-dicarboxylic acid. To be As glycol components other than ethylene glycol, propylene glycol,
Examples thereof include butanediol, neopentyl glycol, diethylene glycol, cyclohexanedimethanol, an ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and the like. Oxycarboxylic acids such as p-oxybenzoic acid can also be utilized.

The above polyester is prepared by a direct polymerization method in which an aromatic dicarboxylic acid and a glycol are directly reacted,
Alternatively, any of transesterification methods in which a dimethyl ester of an aromatic dicarboxylic acid and a glycol are transesterified with each other may be used.

The alumina particles added to the polyester of the present invention may be selected from α, γ and δ type alumina. The average particle size of the alumina particles is 0.5 μm or less, preferably 0.1 μm or less. When the average particle diameter of the alumina particles exceeds 0.5 μm, coarse projections are formed, so that when the film is formed, the scratch resistance of the film is insufficient. Alumina particles are usually contained in the polyester in a proportion of 0.05 to 5% by weight. If it is less than 0.05% by weight, scratch resistance is insufficient, and if it exceeds 5% by weight, it becomes difficult to suppress the agglomeration of alumina particles.

The greatest feature of the composition of the present invention is that the alumina particles contained in the polyester are surface-treated with an alkali metal hydroxide compound. As the alkali metal hydroxide compound used in the present invention, lithium hydroxide, sodium hydroxide, potassium hydroxide and the like are preferable, and particularly when sodium hydroxide is used, excellent effects can be seen. Usually, the alkali metal hydroxide compound is used in a proportion of 0.05 to 1.0% by weight in terms of alkali metal atom based on the alumina particles.

This surface treatment is achieved, for example, by the following method. First, the above-mentioned alkali metal hydroxide compound is added to ethylene glycol and, if necessary, wet pulverization, centrifugation and the like are performed, and then the above-mentioned alumina particles are added and dispersed to obtain a slurry. The obtained slurry is added into the reaction system in the polyester manufacturing process. For example, from the stage where the esterification reaction or transesterification reaction of the polyester production process is substantially completed,
It is desirable to be added at any stage up to the initial polymerization reaction. Other particles may be contained in the composition as long as the object of the present invention is not impaired. Suitable as other particles are inorganic particles such as silica, titanium oxide, kaolin, zeolite, calcium carbonate, heat-resistant polymers such as crosslinked polystyrene, and internal particles.

A film is formed using the polyester composition of the present invention, for example, by a conventional method, for example, extrusion molding. This film is uniaxially or biaxially stretched as necessary. When a stretched film is formed, since alumina particles are contained in the composition, protrusions are formed on the surface of the film and the film is provided with slipperiness. Since the alumina particles are surface-treated, they have good dispersibility. Therefore, minute projections are uniformly formed on the film surface. Such a film has excellent slipperiness, abrasion resistance, and scratch resistance, and does not cause dropout even when processed into a magnetic tape or the like. Such a composition is preferably used as a base film for magnetic tapes, general industries, packaging, etc., or fibers for industrial materials.

[0019]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

The measuring methods used in Examples and Comparative Examples are shown below.

(1) Average particle size The average particle size was obtained by observing with a microscope, at a point where 50% by weight was accumulated in the equivalent spherical distribution of particles.

(2) Number of Aggregated Particles in Polyester A polyester composition is formed into a sheet having a constant thickness,
The maximum diameter and number of internal particles were measured using a microscope and an image analyzer (Luzex IID, manufactured by Nireco Corporation), and ranked according to the number of coarse particles of 5 μ or more as follows.

Rank 1 ... Coarse particle number 0-9 Rank 2 ... Coarse particle number 10-49 Rank 3 ... Coarse particle number 50-99 Rank 4 ... Coarse particle number 100-500 Rank 5. .. Coarse particles number 500 or more If the polyester film obtained is about rank 2, there is no problem in practical use.

(3) Scratch resistance of film When a tape slit into a narrow width (1.27 cm) is rubbed against a metal guide roll and run at high speed for a long time, the guide roll is rubbed against a constant supply tension. The number and depth of scratches on the subsequent tape were visually determined and ranked as follows.

1st grade: No scratches are observed 2nd grade: Scratches are rarely recognized 3rd grade: Scratches are slightly present 4th grade: Scratches are quite large 5th grade: Scratches If the obtained polyester film is of the second grade, there is no problem in practical use.

Example 1 γ-alumina particles (CR-125 manufactured by Baikovsky Co., Ltd.) were added to ethylene glycol so that the ratio of γ-alumina particle solids to ethylene glycol was 20% by weight to obtain a slurry. , Using a high-speed stirring device. Next, in the obtained ethylene glycol slurry of γ-alumina particles, sodium hydroxide was added at a ratio of 0.1% by weight in terms of sodium atom to the γ-alumina particles and dispersed. This was further wet-milled by a bead agitation mill. The average particle size of γ-alumina particles in the obtained slurry is 0.1 μm.
It was m.

An esterification reactor equipped with a stirrer, a dephlegmator, a raw material charging port and a product discharging port was charged with ethylene glycol (E) to terephthalic acid (TPA).
G) was added at a molar ratio of 2.0, and then both were added.
An EG slurry containing 289 ppm of antimony trioxide per TPA unit in terms of antimony atom was supplied. Using this apparatus under the conditions of 2.5 kg / cm ² and 240 ° C., TPA and EG were esterified.

At the time when the esterification is substantially completed, the esterification reaction product has an average particle size of 0, which is 2.0% by weight, based on the polyester composition produced. An ethylene glycol slurry of 1 μm γ-alumina particles was fed.

The esterification reaction product to which the slurry is added is polymerized using a polycondensation reaction device provided with a stirrer, a dephlegmator, a raw material charging port and a product discharging port, and a polyester having an intrinsic viscosity of 0.62 is obtained. A composition was obtained.

The characteristics of the film obtained from this polyester composition are shown in Table 1.

(Example 2) Polymerization was carried out in the same manner as in Example 1 except that γ-alumina particles were added in an amount corresponding to 0.5% by weight based on the resulting polyester composition. I got a thing. The properties of the film obtained from this polyester composition are shown in Table 1.

Examples 3 to 4 In the method of Example 1, Table 1 shows the ratio of sodium hydroxide added to the ethylene glycol slurry of γ-alumina particles in terms of sodium atom to γ-alumina particles. Polymerization was carried out in the same manner except that the above was changed appropriately to obtain a polyester composition. The properties of the film obtained from this polyester composition are shown in Table 1.

Comparative Examples 1 and 2 In the method of Example 1, the ratio of sodium hydroxide added to the ethylene glycol slurry of γ-alumina particles in terms of sodium atom to γ-alumina particles is shown in Table 1. Polymerization was carried out in the same manner except that the above was changed appropriately to obtain a polyester composition. The properties of the film obtained from this polyester composition are shown in Table 1.

Example 5 In the method of Example 1, γ
Using potassium hydroxide as the alkali metal compound added to the ethylene glycol slurry of alumina particles, γ
0.1 wt% in terms of potassium atom based on alumina particles
Polymerization was carried out in the same manner except that potassium hydroxide was added in the proportion of to obtain a polyester composition. The properties of the film obtained from this polyester composition are shown in Table 1.

Example 6 In the method of Example 1, γ
Polymerization was performed in the same manner except that δ-alumina (Al ₂ O ₃ -C manufactured by Nippon Aerosil Co., Ltd.) was used instead of the alumina particles to obtain a polyester composition. The properties of the film obtained from this polyester composition are shown in Table 1.

(Comparative Example 3) In the method of Example 1, sodium hydroxide was added to an ethylene glycol slurry of γ-alumina particles and dispersed therein, and then the slurry was subjected to a bead stirring type crusher without wet crushing treatment. Polymerization was conducted in the same manner except that the polyester composition was used as it was. The properties of the film obtained from this polyester composition are shown in Table 1.

Comparative Example 4 In the method of Example 1, γ
Polymerization was performed in the same manner except that alumina particles were added at a ratio of 6.0% by weight with respect to the resulting polyester composition to obtain a polyester composition. The properties of the film obtained from this polyester composition are shown in Table 1.

Example 7 The polyester composition obtained in Example 1 and a polyester composition containing kaolin particles having an average particle size of 0.4 μm are mixed and melt-extruded at 290 ° C. to give an unstretched film. Obtained. This unstretched film is 3.5 times in the longitudinal direction at 90 ° C and 3.5 times in the transverse direction at 130 ° C.
After being double-stretched, it was heat-treated at 220 ° C. to obtain a biaxially stretched film having a thickness of 15 μm. The properties of this film are shown in Table 2.

Example 8 In Example 7, instead of kaolin particles having an average particle size of 0.4 μm, an average particle size of 0.5 was used.
A 15 μm thick biaxially oriented film was obtained in the same manner except that μm calcium carbonate particles were used. The properties of this film are shown in Table 2.

(Example 9) In Example 7, instead of kaolin particles having an average particle size of 0.4 μm, an average particle size of 0.4
A 15 μm-thick biaxially stretched film was obtained in the same manner except that silica particles of μm were used. The properties of this film are shown in Table 2.

(Comparative Examples 5 to 7) The same procedure as in Example 7 was repeated except that the polyester compositions obtained in Comparative Examples 1 to 3 were used in place of the polyester composition obtained in Example 1. A biaxially stretched film having a thickness of 15 μm was obtained. The properties of this film are shown in Table 2.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

As described above, according to the present invention, since the fine projections of alumina particles are provided on the surface, the slipperiness is excellent,
Moreover, since the number of coarse particles is small, it is possible to obtain a polyester composition which can form a film in which surface abrasion due to friction is extremely small. The film obtained by using the composition containing other particles in addition to the alumina particles has excellent scratch resistance.

Continuation of front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B29L 7:00 4F (72) Inventor Shigetsuji Konagaya 10-24 Toyocho, Tsuruga City, Fukui Prefecture Toyobo Co., Ltd. Film Laboratory Tsuruga Branch Room (72) Inventor Yasuhiro Nishino 10-24 Toyocho, Tsuruga City, Fukui Prefecture Toyobo Co., Ltd. Film Research Laboratory Tsuruga Branch Room

Claims (2)

[Claims] 1. A polyester composition containing 0.05 to 5% by weight of alumina particles having an average particle size of 0.01 to 0.5 μm, wherein the alumina particles are α-alumina, γ-alumina and δ. It is at least one selected from the group consisting of alumina, the alumina particles are surface-treated with an alkali metal hydroxide compound, and the alkali metal hydroxide compound is 0.05% in terms of alkali metal atoms with respect to the alumina particles. From 1.
A polyester composition used in a proportion of 0% by weight. 2. The polyester composition according to claim 1, wherein the alkali metal hydroxide compound is sodium hydroxide.