JP3405016B2 - Polyester composition - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester composition, and more specifically, it contains calcium carbonate particles having a specific particle diameter in a polyester,
The present invention relates to a polyester composition suitable for obtaining a molded product such as a film or a fiber having excellent slipperiness and abrasion resistance.

[0002]

2. Description of the Related Art Generally, polyester such as polyethylene terephthalate has excellent mechanical properties and chemical properties, and is widely used in the field of films such as magnetic tape applications. However, when the polyester is processed into a molded product, there is a problem that the coefficient of friction is high, the slipperiness is insufficient, and the productivity is reduced.

In order to impart slipperiness to polyester, a number of methods have been proposed in the prior art, in which the polyester contains inactive particles to form irregularities on the surface of the molded article to reduce the friction coefficient. Among them, calcium carbonate particles can be produced with various particle diameters and are relatively inexpensive, so there are many proposals from the prior art. For example, calcium carbonate in combination with other particle species (JP Sho 52-7
8953). The slipperiness of polyester films made in this way is improved. However, in recent years, particularly in magnetic tape applications, as the recording density has increased, the requirements for the base film have become more stringent, and it has become necessary to achieve a high degree of compatibility between slipperiness, flatness and abrasion resistance. To meet these requirements, surface treatment of particles, for example, calcium phosphate surface treatment (Japanese Patent Laid-Open No. 1-92265) has been proposed for the purpose of improving the affinity between particles and polyester and preventing the particles from falling off. . Further, those focusing on the crystal structure of particles, such as vaterite-type calcium carbonate (Japanese Patent Laid-Open No. 5-179015) and those focusing on the shape of particles, such as cubic calcium carbonate (Japanese Patent Laid-Open No. 6-34).
It has been proposed that both slipperiness and abrasion resistance are made compatible with each other according to (5947 gazette).

[0004]

However, even when the above-mentioned technique is used, the level required for the base film has not yet been sufficiently satisfied.

An object of the present invention is to obtain a polyester composition which can satisfy the above-mentioned required characteristics, and in particular, can be used to produce a polyester film having excellent slipperiness and abrasion resistance.

[0006]

The above object of the present invention is to provide calcium carbonate particles having an average particle size of 0.2 to 1.0 μm and a particle size variation coefficient of 70 to 95% of 0.0
This can be achieved by a polyester composition characterized by containing 05 to 5.0% by weight.

Particle size variation coefficient (%) = dispersed particle diameter (X) /
Aggregate particle size (Y) × 100 Aggregate particle size: Particle size before ultrasonic dispersion treatment Particle size dispersion: Particle size after ultrasonic dispersion treatment

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a preferred embodiment of the present invention will be described. For calcium carbonate, natural calcium carbonate is crushed and classified by a manufacturing method. Light calcium carbonate synthesized by a blowing method or the like can be used. The calcium carbonate particles in the present invention are not particularly limited, but light calcium carbonate is preferable in that the particle size distribution is generally sharp and the particle size can be easily controlled. As the crystal form of calcium carbonate, any of the three crystal forms of calcite, aragonite, and vaterite can be used, but of these, the calcite form is more preferable. The distinction between crystal structures can be determined by a conventional method, that is, an X-ray diffraction method or the like.

The average particle diameter of calcium carbonate is 0.2 to
It is necessary to be 1.0 μm, preferably 0.3
Is about 0.6 μm. In order to impart slipperiness to the molded product, a certain particle size is required, and conversely, if it is too large, coarse protrusions are generated on the molded product, and wear resistance is reduced. When the average particle diameter is 0.2 to 1.0 μm, the above object can be achieved. Further, in the particle size range of the present invention, the effect of the present invention is remarkable particularly in particles having a small particle size, and the particle size is 0.3 to 0.6 μm.
Is more preferable.

The coefficient of particle size change of the calcium carbonate particles in the present invention is 70 to 95%, preferably 75 to 85%. When the particle size variation coefficient is less than 70%, the particles have a strong aggregating property, and when contained in polyester, it is difficult to control the particle size, and coarse agglomerated particles are likely to occur. The coarse aggregated particles cause a decrease in flatness and abrasion resistance when processed into a film, and the desired effect cannot be obtained. Further, when the particle size variation coefficient is larger than 95%, the particles become close to monodisperse particles, and the particles have uniform particle size, good dispersibility, and easy control of particle size. When it is contained in the above composition and processed into a film, the desired abrasion resistance cannot be obtained. Conventionally, in order to improve the abrasion resistance, a technical goal has been to reduce the agglomeration of particles as close as possible and bring the particles into a monodispersed state. However, as a result of various investigations, it was found that particles having a tendency to agglomerate slightly more than monodisperse particles more effectively act on the sharpness in the polyester film. The reason for this is not clear, but if the particles have a cohesive property, the particles are deformed by an external force in the film, have flexibility, and disperse the stress, and it is considered that the abrasion of the film surface and the falling of the particles are reduced. To be

The calcium carbonate particles in the present invention preferably have a particle size distribution ratio of 2.5 or less. The particle size distribution ratio is an index representing the sharpness of the particle size distribution, and the closer the value is to 1, the sharper the distribution. In the present invention, when the particle size distribution ratio exceeds 2.5, a large number of coarse particles are mixed in the particles, so that when the film is formed, coarse projections may be formed and the particles may fall off. The particle size distribution ratio is more preferably 2.0 or less, and particularly preferably 1.7 or less.

The calcium carbonate particles in the present invention may use a dispersant or a surface treatment agent for controlling cohesiveness or improving affinity with polyester. Examples of such dispersants or surface treatment agents include silane coupling agents, titanium coupling agents, esters of carboxylic acid, phosphoric acid, sulfonic acid or the like or metal salts thereof, or polyacrylic acid and its derivatives and metal salts thereof. Etc. can be mentioned. Among these, polyacrylic acid or a copolymer of polyacrylic acid and its derivative and a metal salt thereof are particularly preferable.

The calcium carbonate of the present invention can be obtained by controlling the grinding process in the final stage. As an example of the production method, calcium carbonate powder obtained by a conventional method is made into an ethylene glycol suspension, and a surface treatment agent is added to this suspension, followed by wet pulverization. Here, by appropriately adjusting the amount of the surface treatment agent and the treatment conditions of the wet pulverization, it is possible to obtain particles having a target particle size and a particle size change coefficient.

The polyester in the present invention is a polyester produced by a polycondensation reaction using a difunctional component such as an aromatic dicarboxylic acid or its dialkyl ester and a glycol component as main raw materials. Of these, those mainly composed of polyethylene terephthalate are preferable. The polyester may be replaced with another dicarboxylic acid or glycol component in an amount of 20 mol% or less as a copolymerization component. Examples of such copolymerization components include dicarboxylic acid components such as adipic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid and 5-sodium sulfoisophthalic acid, trimellitic acid and pyromellitic acid. Polycarboxylic acid component, tetramethylene glycol, hexamethylene glycol, diethylene glycol, propylene glycol, neopentyl glycol, polyoxyalkylene glycol, p-xylylene glycol, 1,4-hexanedimethanol, 5-
Examples include diol components such as sodium sulforesorcin. Further, additives such as a heat resistance stabilizer, an antioxidant and an antistatic agent may be added if necessary.

The content of calcium carbonate in the present invention with respect to the polyester composition is 0.005 to 5.0% by weight, preferably 0.01 to 4.0% by weight. If the content is less than 0.005% by weight, the slipperiness becomes insufficient when molded into a film or the like, while if it exceeds 5.0% by weight, the dispersibility deteriorates and coarse projections are generated on the film surface. Is not preferable because the flatness is deteriorated.

Further, other particle species may be contained within a range not impairing the object of the present invention. Among these particle species, it is more preferable to use aluminum oxide in order to achieve the object of the present invention.

The particle size of this aluminum oxide is 0.01
The thickness is preferably 0.3 to 0.3 μm, more preferably 0.05 to 0.25 μm. The content of aluminum oxide in the polyester composition is 0.005 to 5.0.
It is preferably in the range of 0.1% by weight, more preferably 0.
It is from 01 to 4.0% by weight. By using aluminum oxide in this range, the effect of the present invention can be further improved.

The calcium carbonate particles may be added to the thermoplastic polyester at any time, but preferably between the transesterification reaction and the polycondensation reaction. In addition to the production method of adding to such a reaction system, the polyester may be directly kneaded and mixed with the molten polyester.

[0019]

EXAMPLES The present invention will be specifically described below with reference to examples. The physical properties in the examples were measured as follows.

A. Particle size of particles Dilute an ethylene glycol dispersion of particles in water and use a laser diffraction / scattering particle size distribution analyzer (LA70 manufactured by Horiba, Ltd.).
0) is used to measure the particle size distribution. Light transmittance 80 ~
Adjust the water dilution concentration to 95%, and measure at 25
The particle size with an integrated volume fraction of 50% in the equivalent spherical distribution measured at ℃ and a circulation rate of 570 ml / min is the agglomerated particle size (= average particle size). They are d25 and d75, respectively. In addition, before the particle size measurement, ultrasonic dispersion treatment with a frequency of 39 kHz was performed for 5 minutes, and then the particle size with an integrated volume fraction of 50% measured in the same manner was used as the dispersed particle size.

B. Value measured at a concentration of 0.1 g / cc in orthochlorophenol at an intrinsic viscosity of 25 ° C.

C. Sliding property of the film Slit to a width of 1/2 inch and use a tape running tester TBT-300 type [manufactured by Yokohama System Laboratory Co., Ltd.] to run at 20 ° C. and 60% RH atmosphere to obtain initial friction. The coefficient μK was calculated from the following formula. The guide diameter is 6
mmφ, the guide material is SUS27 (surface roughness 0.
2S), winding angle is 180 °, traveling speed is 3.3 cm
/ Sec. μk = 0.733 × log (T1 / T2) T1: Outlet pressure T2: Inlet pressure The above μK of 0.35 or less has good slipperiness. When μK is larger than 0.35, the slipperiness during film processing or as a product becomes extremely poor.

D. The abrasion-resistant polyester composition of the film was formed into a biaxially stretched film by a usual method, and a tape-shaped roll slit into 1/2 inch was wound around a stainless steel SUS-304 guide roll at an angle of 60 °.
The sample was rubbed at a speed of 250 m / min and a tension of 95 g for 500 m, ranked as follows according to the amount of white powder generated on the surface of the guide roll, and grade 2 or higher was passed. 1st grade: No white powder generated 2nd grade: Small amount of white powder generated 3rd grade: White powder generated 4th grade: White powder generated considerably Scratch resistance of film D. The abrasion resistance was evaluated, and the scratches in the film at that time were observed with a microscope 50 times, the number of scratches per visual field was determined, and grade 2 or higher was passed. 1st grade: No scratches 2nd grade: 1-3 scratches 3rd grade: 4-10 scratches 4th grade: 11 scratches or more Example 1 Ammonium polyacrylate salt 10 parts of the surface-treated calcium carbonate particles and 90 parts of ethylene glycol were wet-milled to obtain a calcium carbonate / ethylene glycol dispersion slurry. The average particle size of this calcium carbonate is 0.48
The particle size variation coefficient was 81%. On the other hand, to 100 parts of dimethyl terephthalate and 64 parts of ethylene glycol, 0.04 part of manganese acetate as a catalyst was added and 0.03 part of antimony trioxide was added for transesterification reaction, and then the reaction product was treated with trimethyl phosphate as a phosphorus compound.
04 parts was added, and further 1 part of the slurry (A) prepared above was added to carry out a polycondensation reaction to obtain an intrinsic viscosity of 0.6.
18 polyethylene terephthalate compositions were obtained. Next, this polyethylene terephthalate composition was melt extruded at 290 ° C. to obtain an unstretched film. After that, the film was stretched at 90 ° C in the length and width directions three times each, and then at 220 ° C for 10
After heat setting for 2 seconds, a biaxially stretched film having a thickness of 15 μm was obtained.

The evaluation results of this film are shown in Table 1. The content of calcium carbonate particles in the film was 0.1% by weight. The film has a μK of 0.26 and abrasion resistance of 1
It was a grade 2 and a scratch resistance grade 2, and was a film excellent in slipperiness, abrasion resistance and scratch resistance.

Examples 2 to 5 Films were obtained in the same manner as in Example 1 except for the changed parts shown in Table 1. Within the scope of the invention, Table 1
As shown in, the film was excellent in slipperiness, abrasion resistance, and scratch resistance.

Comparative Examples 1 to 5 Films were obtained in the same manner as in Example 1 except for the changed parts shown in Table 2. Abrasion resistance of the obtained film,
The scratch resistance was insufficient and the object of the present invention could not be achieved.

[0027]

[Table 1]

[Table 2]

[0028]

The polyester composition containing calcium carbonate of the present invention has good abrasion resistance and scratch resistance when formed into a molded product. A polyester film comprising the polyester composition of the present invention can be preferably used as a base film for magnetic recording.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-157877 (JP, A) JP-A-4-282226 (JP, A) JP-A-4-40623 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C08L 67/00-67/02

Claims (5)

(57) [Claims] 1. Calcium carbonate particles having an average particle size of 0.2 to 1.0 μm and a particle size variation coefficient of 70 to 95% are contained in an amount of 0.005 to 5.0% by weight. Polyester composition. Particle size variation coefficient (%) = dispersed particle diameter (X) / aggregated particle diameter (Y) × 100 Aggregated particle diameter: particle diameter before ultrasonic dispersion treatment dispersed particle diameter: particle diameter after ultrasonic dispersion treatment 2. The particle size distribution ratio of calcium carbonate particles is 2.
The polyester composition according to claim 1, which is 5 or less. Particle size distribution ratio = d25 / d75 d25: In the volume-based cumulative distribution of the particles, the particle size at 75% of the total volume from the large particle size side d75: In the volume-based cumulative distribution of the particles, from the large particle size side to the total volume Particle size at 75% 3. The polyester composition according to claim 1, wherein the crystal form of the calcium carbonate particles is calcite type. 4. The polyester composition according to claim 1, wherein the calcium carbonate particles are surface-treated with a polycarboxylic acid salt. 5. The aluminum oxide particles having an average particle diameter of 0.01 to 0.3 μm are contained in an amount of 0.005 to 5.0% by weight, and the aluminum oxide particles are contained in an amount of 0.005 to 5.0% by weight.
The polyester composition according to the item.