JPH0455464A - Thermoplastic polyester composition - Google Patents

Abstract

PURPOSE:To obtain the title composition capable of obtaining fibers or films of excellent travelability and wear resistance, esp. suitable for magnetic tapes by incorporating a thermoplastic polyester with spherical vaterite-type calcium carbonate particles. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100 pts. wt. of a thermoplastic polyester made up of (1) a carboxylic acid component predominant in an aromatic dicarboxylic acid and (2) a glycol component predominant in an aliphatic glycol with (B) 0.01 - 10 pts. wt. of vaterite- type calcium carbonate having >= 30 m<2>/g in the specific surface area determined by the BET adsorption technique, 0.01 - 5mum in mean particle diameter and 0.3 - 0.52 in the view factor (f) of the equation (V is particle volume mum<3>; D is maximal diameter mum of the projected area of particle), prepared by blowing carbon dioxide in calcium hydroxide in an alcoholic solvent to once convert into an amorphous gelled product, which is then put to regulation for particle shape, particle size distribution, and particle diameter, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thermoplastic polyester composition, and more specifically, substantially spherical vaterite-type calcium carbonate particles are blended into a thermoplastic polyester, and The present invention relates to a thermoplastic polyester composition suitable for producing films or fibers with excellent properties and abrasion resistance.

[Prior Art] Thermoplastic polyesters, such as polyethylene terephthalate, generally have excellent mechanical properties and can be used for films,
Widely used as molded products such as fibers. usually,
For the purpose of imparting lubricity to the molded article, a method of producing the polyester is carried out by incorporating inert particles into the polyester to impart irregularities to the surface of the molded article. Although there are various types of such inert particles, it is a well-known fact that calcium carbonate particles are widely used because they have a wide variety of particle sizes and are inexpensive. However, calcium carbonate particles generally have a poor affinity with the polyester, and have a wide particle size distribution that makes it impossible to remove coarse particles, resulting in poor abrasion resistance of molded products.

In order to solve this problem, there have been many proposals regarding surface treatment of calcium carbonate particles.

For example, JP-A-49-130448 (surface treatment with bis fatty acid amide compound and fatty acid ester), JP-A-55-46538 (surface treatment with acrylic acid copolymer), JP-A-60-71632 (Surface treatment with carboxylic acid compound) and JP-A-1-92265 (Surface treatment with calcium phosphate) are known.

Recently, in the field of magnetic tape, there has been a particularly severe demand for improved running performance and wear resistance due to a marked increase in the contact running speed with guide bins. Even if the surface treatment of type calcium carbonate particles is improved, it is still insufficient. As shown in FIG. 2, the calcite type layer and calcium acid particles have strong peaks in the X-ray diffraction chart at diffraction angles of 29.4', 36.0', 40.4°, 43°1', 47. This is what is observed at the 5'', 48.5 position.

[Problems to be Solved by the Invention] The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and to improve runnability and durability by blending substantially spherical vaterite-type calcium carbonate particles into thermoplastic polyester. The object of the present invention is to obtain a polyester composition from which films and fibers with excellent abrasion properties can be produced.

[Means for Solving the Problems] The object of the present invention described above is to produce a thermoplastic polyester (A) containing aromatic dicarboxylic acid as the main carboxylic acid component and aliphatic glycol as the main glycol component (A) in a proportion of B to 100 parts by weight. , E, T, specific surface area measured by method is 30 m2/g or more and average particle size is 0.01 to 5.0
μm, and the shape factor f expressed by the following equation (I) is 0.
This can be achieved by a thermoplastic polyester composition containing 0.01 to 10 parts by weight (B) of vaterite-type calcium carbonate particles having a particle diameter of 30 to 0.52.

f=V/D3 ・・ ・ ・ ・ ・ (I)
(However, ■ is the particle volume (μm3), and D is the maximum diameter (μm) in the projected plane of the particle.) Calcium carbonate particles (B) in the present invention are defined in the X-ray diffraction chart as shown in FIG. The strong peak has a diffraction angle of 24.9°,
These are observed at positions of 27.0°, 32.8°, 43.9°, and 50.0°. It is generally known that the crystal structure of calcium carbonate is not only the vaterite type but also the calcite type and the aragonite type, but the vaterite type calcium carbonate can be obtained by a synthetic method that is substantially spherical and has an excellent particle size distribution. Moreover, since it has surface activity, it is considered to be superior because it has strong interaction with polyester in polyester and less particles fall off. The average particle size is
It can be arbitrarily selected depending on the purpose of the molded article made from the thermoplastic polyester composition. When used in films or fibers, a certain level of particle size is required to ensure sufficient slipperiness in the molded product, and conversely, if the particle size is too large, coarse protrusions will form on the molded product, reducing wear resistance. 0.01-5°0pm, preferably 0.0pm to reduce
It is 5-3°011m. In addition, the average particle diameter here is the circular optical average diameter (μm) when 1000 particles are observed with a scanning electron microscope. In addition, in order to improve the affinity with polyester using the surface activity of vaterite-type calcium carbonate, it is necessary to make the particles porous and increase the specific surface area, and B, E, and T.

It is preferably 30 m2/g or more, more preferably 50 m2/g or more, as measured by the method. Further, the specific surface area is preferably 600 m2/g or less. The shape of the particles is preferably substantially spherical from the viewpoint of running properties when made into a film or fiber, and the shape factor f shown by the following formula (I) is 0.
．． It needs to be in the range of 30 to 0°52. Furthermore,
It is preferable that f is in the range of 0°35 to 0.52.

f=V/D3... (I) (However,
(2) is the particle volume (μm3), and D is the maximum diameter (μm) of the particle in the projection plane. ) The vaterite-type calcium carbonate particles as described above can be produced by, for example, blowing carbon dioxide gas into calcium hydroxide in an alcoholic solvent such as methanol or ethanol to form an amorphous gel-like substance.
It is possible to manufacture it by a method of synthesis while adjusting the particle shape, particle size distribution, and particle size. Note that the particle shape, particle size distribution, and particle size can be controlled by synthesis conditions and additives, but as mentioned above, from the viewpoint of running properties when molded into fibers or films, a substantially spherical shape is preferable. , and in terms of wear resistance,
It is preferable that the particle size distribution is sharp, and for this purpose classification, filtration, etc. may be performed.

Generally, synthetic vaterite-type calcium carbonate has a problem in that it is easily affected by water, and its crystals are transformed into calcite-type by water. Further, the presence of moisture in polyester is also undesirable as it causes hydrolysis. Therefore, it is preferable that the water content in the synthetic vaterite-type calcium carbonate particles or a slurry thereof as described above be kept to 5 wt % or less based on the particles.

Note that the particles may be surface-treated for the purpose of suppressing such crystal structure transition. As such a surface treatment agent, since calcium carbonate is basic, it is preferable to use a compound having an acid functional group such as carboxylic acid, phosphoric acid, or sulfonic acid. It doesn't matter.

The thermoplastic polyester (A) in the present invention is a polymer produced by a polycondensation reaction using as main raw materials a difunctional component such as an aromatic dicarboxylic acid or its dialkyl ester and a glycol component. Among these, those mainly composed of polyethylene terephthalate and polyethylene-2,6-naphthalate are particularly preferred. The polyester may be a homopolyester or a copolyester (examples of copolymer components include adipic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalene-2,6-dicarboxylic acid, 5-sodium Dicarboxylic acid components such as sulfoisophthalic acid, polyvalent carboxylic acid components such as trimellitic acid and pyromellitic acid, and tetramethylene glycol, hexamethylene glycol, diethylene glycol,
Diol components such as propylene glycol, neopentyl glycol, polyoxyalkylene glycol, p-xylylene glycol, 1,4-cyclohexane dimetatool, and 5-sodium sulforesorcin are mentioned, and the carboxyl terminal group of the polyester is 10 e
A range of q/t to 70 eq/t is preferred. Note that additives such as heat stabilizers, antioxidants, and antistatic agents may be added as necessary.

The polyester composition of the present invention can be produced by a polyester production method in which substantially spherical vaterite-type calcium carbonate particles are added to a reaction system as a glycol slurry, which is a raw material for the polyester, as described above.

At this time, the glycol slurry of the vaterite-type calcium carbonate particles may be improved in dispersibility using stirring treatment, ultrasonication, or a normal wet media type dispersion machine, or removal of aggregated particles or coarse particles by classification or filtration. It is more preferable to add it to the reaction system. The timing of addition to the reaction system is arbitrary, but preferably from before the transesterification reaction to before the start of pressure reduction in the polycondensation reaction.

In addition to the production method of adding to the reaction system,
It is also possible to directly insert the wire into the molten polyester. In this case, the vaterite-type calcium carbonate particles may be dried and then directly injected into the polyester as a powder, or they may be kneaded under reduced pressure in the form of an alcohol slurry as a synthesis medium. Considering dispersibility, it is preferable to directly feed the slurry into a kneading machine with high shear force while reducing pressure.

[Examples] Next, the present invention will be specifically explained using Examples and Comparative Examples.

(1) Evaluation of the average particle size of calcium carbonate particles Calcium carbonate particles were spread on a slide, deposited, and then observed with a scanning electron microscope.
It was evaluated in μm).

(2) Evaluation of specific surface area of calcium carbonate particles Normal B,
The specific surface area (m2/g) was evaluated using the E, T, method.

(3) Evaluation of shape factor of calcium carbonate particles After spreading calcium carbonate particles on a slide and depositing them, 1000 particles were observed with a scanning electron microscope, and the maximum diameter (μm) and area average diameter in the projected plane were measured. The shape factor f expressed by the following equation (1) was calculated using the particle volume (μm 3 ) calculated from (μm).

f=V/D'...Full...φ (1) (However,
(2) is the particle volume (μm3), and D is the maximum diameter (μm) of the particle in the projection plane. ) (4) Evaluation of abrasion resistance The obtained polyester composition was made into a biaxially stretched film by the usual method, and a tape-like roll with narrow width slits was stretched at high speed and over a long length under constant tension on a guide roll made of stainless steel 5US-304. The guide rolls were rubbed for a period of time and ranked according to the amount of white powder generated on the surface of the guide roll as follows, and grade 1 was considered to be a pass.

Grade 1: No white powder generated. Grade 2: Some white powder generated. Grade 3...・・・・・・・・・ Considerable occurrence of white powder (5) Evaluation of slipperiness The obtained polyester composition was made into a two-wheel stretched film by the usual method, and the coefficient of static friction (μ, ) was determined by the ASTM-1894B method. was measured.

(6) Evaluation of surface unevenness The obtained polyester composition was made into a two-wheeled stretched film using the usual method, and using a Surfcom surface roughness meter according to JISBO601, the needle diameter was 2 μm, the load was 70 mg, and the measurement standard length was 0.
．． The center line average roughness (Ra) was measured under conditions of 25 mm and a cutoff of 0.08 mm.

Example 1 Synthetic vaterite-type calcium carbonate particles with an average particle size of 0.30 μm (B, E, T, specific surface area 137 m / g 1 shape coefficient f = 0.49, the X-ray diffraction chart of the particles is shown in Figure 1. It was confirmed that the calcium carbonate particles had a vaterite-type crystal structure.) 10 parts by weight of calcium carbonate particles and 90 parts by weight of ethylene glycol were mixed and dispersed with ultrasonic waves for 10 minutes, resulting in substantially spherical vaterite-type carbonate particles. An ethylene glycol slurry (X-1) of calcium particles was obtained.

On the other hand, 100 parts by weight of dimethyl terephthalate, 64 parts by weight of ethylene glycol, and 0% magnesium acetate as a catalyst.
．． A transesterification reaction was carried out by adding 0.6 parts by weight. Next, 5 parts by weight of the slurry (X-1) previously prepared and 0.03 parts by weight of antimony dioxide as a catalyst were added to the reaction product, and a poly-condensation reaction was carried out to form a polyethylene terephthalate composition with an intrinsic viscosity of 0.624. (Y-1) was obtained.

Next, this polyethylene terephthalate composition (Y-1
) was melt-extruded at 290°C to obtain an unstretched film. Thereafter, the film was stretched 3 times in length and width at 90°C, and then heat treated at 220°C for 15 seconds to obtain a two-wheel stretched film with a thickness of 15 μm.

When this film was evaluated, Ra=0.018μm1
μ=0.68, the abrasion resistance evaluation was grade 1, and the film had excellent running properties and abrasion resistance.

Examples 2 to 5 Biaxially stretched polyester films were obtained in the same manner as in Example 1, except that the average particle diameter, specific surface area, shape factor, and addition amount of the calcium carbonate were changed to the values shown in Table 1. The evaluation results of these films are shown in Table 1, and they were found to have excellent running properties and abrasion resistance.

Comparative Example 1 Synthetic calcium carbonate particles (B
, E, T, specific surface area 8m2/g, shape factor f=0
．． 31. An X-ray diffraction chart of the particles is shown in FIG. 2, and it was confirmed that the calcium carbonate particles had a calcite type crystal structure. ) and 90 parts by weight of ethylene glycol were mixed and subjected to ultrasonic dispersion treatment for 10 minutes to obtain an ethylene glycol slurry (X-2) of calcite-type calcium carbonate particles.

On the other hand, 100 parts by weight of dimethyl terephthalate, 64 parts by weight of ethylene glycol, and 0% magnesium acetate as a catalyst.
．． A transesterification reaction was carried out by adding 0.6 parts by weight. Next, 5 parts by weight of the slurry (X-2) previously prepared and 0.03 parts by weight of antimony trioxide as a catalyst were added to the reaction product to perform a polycondensation reaction, resulting in a polyethylene terephthalate composition with an intrinsic viscosity of 0.624. (Y-2) was obtained.

Next, this polyethylene terephthalate composition (Y-2
) was melt-extruded at 290°C to obtain an unstretched film. Thereafter, the film was stretched 3 times in length and width at 90°C, and then heat treated at 220°C for 15 seconds to obtain a biaxially stretched film with a thickness of 15 μm.

When this film was evaluated, Ra=0.019μm1
μ, = 0.89, wear resistance evaluation grade 3, wear resistance,
This was not necessarily favorable in terms of running performance.

Comparative Examples 2 to 4 Biaxially stretched polyester was produced in the same manner as in Comparative Example 1, except that the particle type, crystal structure, average particle size, specific surface area, shape factor, and addition amount were changed to the values shown in Table 2. Got the film. The evaluation results of these films are shown in Table 2.
It was not necessarily favorable in terms of running performance and wear resistance.

[Effects of the Invention] The calcium carbonate particles in the polyester composition of the present invention are substantially spherical in shape and have good dispersibility, so they have excellent runnability when molded into films or fibers, and have a crystalline structure. Since it is a vaterite type, it has good affinity with polyester, and calcium carbonate does not easily fall off from the polyester composition, resulting in good abrasion resistance. Therefore, although the polyester composition of the present invention is effective in making fibers, films, and other molded products, it can be particularly preferably used in magnetic tapes that are used repeatedly by friction.

[Brief explanation of the drawing]

FIG. 1 is an X-ray diffraction chart of vaterite-type calcium carbonate, and FIG. 2 is an X-ray diffraction chart of calcite-type calcium carbonate.

Claims (1)

[Scope of Claims] B. E. T. The specific surface area measured by the method is 30 m^2/g or more, the average particle diameter is 0.01 to 5.0 μm, and the shape factor f shown by the following formula (I) is in the range of 0.30 to 0.52. Vaterite type calcium carbonate particles (B) 0.01 to 10
A thermoplastic polyester composition comprising parts by weight. f=V/D^3・・・・・・・・・(I) (However, V is the particle volume (μm^3), and D is the maximum diameter of the particle in the projected plane (μm).)