JPH1160710A - Production of polyester containing inactive particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyester in which inactive particles suitable for films are homogeneously dispersed. SOLUTION: This method for producing a polyester containing inactive particles comprises adding the ethylene glycol slurry of the inactive particles to the esterification product of terephthalic acid with ethylene glycol. Therein, the esterification product having a viscosity of <=5 dPa.s at 250 deg.C is mixed with the inactive particle ethylene glycol slurry having a viscosity of <=5 dPa.s at 20 deg.C in a condition that the difference (absolute value) between the viscosities is <=1 dPa.s, stirred for 10-60 min and subsequently polycondensed until giving an intrinsic viscosity of 0.5-1.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyester in which inert fine particles suitable for a film are uniformly dispersed.

[0002]

2. Description of the Related Art Polyethylene terephthalate or a polyester based on polyethylene terephthalate has excellent physical and chemical properties.
Widely used for molded products. Among them, for films, they are widely used such as base films for magnetic tapes such as audio and video, photographic films, electric insulating films, base films for gold and silver threads, and films for general packaging.

In the production of a polyester film, it is essential to have good processability in processes such as melt extrusion, stretching, heat treatment, winding, slitting, coating of a magnetic layer, and coating of a gas barrier layer. Further, the product film is required to have good slipperiness and abrasion resistance.

Heretofore, in order to meet such demands, it has been customary to incorporate inactive fine particles into polyester to impart appropriate irregularities to the film surface.

[0005] In the field of magnetic tapes used for recording information at a high density, such as digital audio tapes, video tapes, and memories, the uniformity of the surface of a base film is increasingly required. Therefore, it is required that such a polyester for a film does not have any coarse particles due to the aggregation of the added fine particles, or if they do, they must have a small size and a very small number. Because
Such coarse particles cause undesired phenomena such as dropout (dropout of stored information) and reduction in S / N ratio (ratio between signal and noise) when formed into a magnetic tape.

[0006] Polyester containing inert fine particles,
Usually, it is produced by a method in which an ethylene glycol slurry (referred to as an EG slurry) of inert fine particles is added to an esterified product (oligomer) of terephthalic acid and ethylene glycol to carry out a polycondensation reaction. At this time, various attempts have been made to suppress the generation of coarse particles by improving the dispersion of inert fine particles.

For example, JP-A-53-125495 proposes a method in which inert fine particles are finely dispersed using a special stirring blade and then added. Also, JP-A-56-88426
In Japanese Patent Application Laid-Open Publication No. H11-264, a method is proposed in which a dispersant is used at the time of preparing a slurry to improve dispersibility.

However, these methods improve the dispersion of the inert fine particles in the slurry, but have the problem that when the slurry is added to the reaction system and polycondensed, the fine particles aggregate in the polymer. The effect was not enough.

A method has also been proposed in which a slurry of inert fine particles is added to an oligomer and then treated with a special high-shearing disperser to prevent agglomeration of the particles (Japanese Patent Laid-Open No. 64-31818). Gazettes). However, even with this method, the aggregation of the fine particles is unavoidable with the progress of the polycondensation reaction, and further, the higher the viscosity, the more the coarse particles increase.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a polyester in which inert fine particles suitable for a film are uniformly dispersed.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and the gist of the present invention is that an EG slurry is added to an esterified product of terephthalic acid and ethylene glycol to carry out a polycondensation reaction to produce inert fine particles. In the method for producing a polyester containing, the viscosity at 20 ° C is 5 dPa · s with respect to the esterified product having a viscosity at 250 ° C of 5 dPa · s
EG slurry is added under the condition that the viscosity difference (absolute value) with the esterified product is 1 dPa · s or less, and after stirring for 10 to 60 minutes, the polycondensation reaction is performed until the intrinsic viscosity becomes 0.5 to 1.0. A method for producing a polyester containing inert fine particles, characterized in that:

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the present invention, first, an esterified product is obtained by subjecting terephthalic acid and ethylene glycol to an esterification reaction.

The esterification reaction is carried out batchwise, semi-batchwise or continuously, and usually the average degree of polymerization of the esterified product is 6%.
It is carried out under the condition that 1010. This is the most preferable condition in consideration of ease of reaction control, suppression of oligomer scattering, speed of polycondensation reaction, and the like.

On the other hand, EG slurry is prepared by adding and mixing inert fine particles with ethylene glycol.

As the inert fine particles, silicon dioxide, calcium carbonate, magnesium carbonate, ammonium silicate, talc, titanium dioxide, kaolin, clay, zeolite,
Inorganic fine particles such as mica, calcium phosphate, barium sulfate and the like, and crosslinked polymer fine particles such as crosslinked polyester, polyacrylate and polystyrene, organic silicone fine particles, and organic fine particles such as fluororesin fine powder are used.

The inert fine particles have an average particle size of 0.01.
３3 μm is preferred. When the average particle size is less than 0.01 μm, process passability, slipperiness and abrasion resistance of a product film become insufficient. On the other hand, when the average particle size exceeds 3 μm, the transparency as a film becomes insufficient and
When using magnetic tape, it can easily cause dropout.

In preparing the EG slurry, a known surfactant or an ammonium salt such as tetraethylammonium hydroxide can be used in combination. Further, the surface of the inert fine particles can be treated with a known surface treatment agent such as a silane coupling agent, a titanium coupling agent, a polyacrylate metal salt, or an acrylic acid / acrylate copolymer.

The EG slurry has a concentration of inert fine particles.
Suitably it is between 0.5 and 25% by weight. If this concentration is too high, the viscosity of the EG slurry will be too high, while if this concentration is too low, the amount of ethylene glycol will increase, and when added to the esterified product, the temperature of the esterified product will decrease and it will be easily solidified. Also, the amount of diethylene glycol by-produced increases and the quality of the produced polyester deteriorates.

Next, the EG slurry is added to the esterified product, and the viscosity at 250 ° C. of the esterified product is 5 dPa ·
s or less, preferably 3 dPa · s or less, 20 g of EG slurry.
The viscosity at 5 ° C. is 5 dPa · s or less, preferably 3 dPa · s
s or less, and the esterified compound and EG when adding the EG slurry
It is necessary that the viscosity difference (absolute value) with the slurry be 1 dPa · s or less, preferably 0.5 dPa · s or less.

When the viscosity of the esterified product and the EG slurry is large, the viscosity of the whole system becomes high, so that the dispersion of the inert fine particles becomes insufficient, and coarse particles in which the fine particles are aggregated are easily formed. Also, if the difference in viscosity between the two when the EG slurry is added to the esterified product is larger than 1 dPa · s, the dispersion of the inactive fine particles will also be insufficient, and the amount of coarse particles due to aggregation will increase significantly.

Since the EG slurry at room temperature is usually added to the esterified product at a temperature of about 250 ° C., the difference between the above viscosities is almost equal to the viscosity difference at the time of addition.

The viscosity of the esterified product can be adjusted by the degree of polymerization, and the viscosity of the EG slurry can be adjusted by the concentration of the inert fine particles.

The addition of the EG slurry to the esterified product is as follows:
It is desirable to carry out the reaction at a temperature of 230 to 260 ° C. under a pressure higher than the vapor pressure of the reaction gas comprising ethylene glycol and water. If the temperature of the esterified product at this time is too low, the temperature of the content decreases when the EG slurry is added, and the viscosity partially increases, so that aggregation of the inert fine particles easily occurs. On the other hand, if the temperature of the esterified product at this time is too high, the added ethylene glycol tends to be scattered or the color tone of the esterified product is deteriorated.

When the EG slurry is added to the esterified product, the EG slurry is charged with stirring, but it is necessary to continue stirring for 10 to 60 minutes, preferably 30 to 60 minutes, after the charging is completed. Yes, this prevents the generation of coarse particles. If the stirring time is less than 10 minutes, mixing with the esterified product is not sufficiently performed, and it is difficult to prevent generation of coarse particles. On the other hand, when the stirring time exceeds 60 minutes, by-products of diethylene glycol increase and the quality of the polyester deteriorates.

It is appropriate that the amount of the EG slurry added is such that the amount of the inert fine particles is 0.05 to 3% by weight based on the produced polyester. If the amount of the inert fine particles is too small, the process passability and the slipperiness and abrasion resistance of the product film become insufficient. On the other hand, if the amount is too large, the film becomes poor in transparency.

The time for charging the EG slurry is usually about 10 to 45 minutes. By increasing the charging time, it is possible to shorten the stirring time after the charging is completed.

If necessary, alkali metal compounds such as lithium acetate and magnesium acetate, alkaline earth metal compounds such as lithium acetate and magnesium acetate for suppressing the generation of coarse particles and imparting electrostatic pinning properties, and thermal stability. Various additives such as a phosphoric acid ester and an ammonium phosphate salt for giving are added.

After the EG slurry is added to the esterified product and the mixture is stirred for a predetermined time, a polycondensation reaction is performed. Before the polycondensation reaction, it is preferable to filter the mixture using a filter having an opening of about 3 to 5 μm. . In addition, prior to the polycondensation reaction, a known means of performing a stirring treatment under a high shear may be additionally employed.

The polycondensation reaction can be carried out by a conventional method. For example, antimony trioxide, germanium dioxide,
Add a polycondensation catalyst such as tetrabutyl titanate, and add 0.
260-300 ° C under reduced pressure of about 01-15 hPa, preferably 2
This may be performed at a temperature of 75 to 290 ° C. until a polyester having a predetermined intrinsic viscosity is obtained.

In the present invention, it is necessary that the intrinsic viscosity of the polyester is 0.5 to 1.0, preferably 0.55 to 0.75. If the intrinsic viscosity is less than 0.5, the general properties of the film, such as strength, cannot be maintained, while if the intrinsic viscosity exceeds 1.0, the melt-forming properties deteriorate.

[0032]

Next, the present invention will be described in detail with reference to examples. The characteristic values were measured by the following method. (1) Intrinsic viscosity [η] Measured at a temperature of 20 ° C. using an equal weight mixture of phenol and ethane tetrachloride as a solvent. (2) DEG content Polyester is added with methanol solution of potassium hydroxide, heated and decomposed, and gas chromatograph CG- manufactured by Shimadzu Corporation is used.
Ethylene glycol and diethylene glycol were quantified using 9A, and the ratio of diethylene glycol to the total amount of both was determined. (3.5 mol% or less passed) (3) Viscosity of Esterified Product It was measured at 250 ° C. using a viscotester manufactured by Rion: Model VT-03 (single cylinder rotational viscometer). (4) Viscosity of EG slurry The viscosity was measured at 20 ° C. using a visco tester manufactured by Rion: Model VT-03 (single cylinder rotational viscometer). (5) Degree of particle dispersion A small amount of polyester is sandwiched between two cover glasses.
After being melt-pressed at 80 ° C. and quenched, the number of coarse particles was observed with a microscope, and the particles were ranked as grades 1 to 4 (grades 1 and 2 passed). Here, particles having a size exceeding the larger value of four times the average primary particle size or 10 μm, whichever was larger, were determined to be coarse particles. Primary: coarse particle number is 10 / mm ² or less Grade 2: the number of coarse particles 11 to 30 pieces / mm ² 3 Grade: number of coarse particles 31-50 pieces / mm ² 4 grade: number of coarse particles is 51 pieces / Mm ² or more

Example 1 Terephthalic acid and ethylene glycol were esterified by a conventional method to give an average degree of polymerization of 8.0 and a viscosity at 250 ° C.
An esterified product of 0.5 dPa · s was obtained. On the other hand, silicon dioxide (SiO ₂ ) having an average particle size of 1.25 μm is added to ethylene glycol.
And added with 3% by weight and stirred and mixed.
An EG slurry of 0.3 dPa · s was prepared. The above esterified product is charged into a polycondensation reaction tank, and the temperature is set to 250 ° C. and the pressure is set to 0.2.
After maintaining the pressure at MPaG and adding 3% by weight of ethylene glycol containing 0.10% by mole of lithium acetate (LiOAc) based on the terephthalic acid component, the amount of SiO ₂ is 0.7% by weight with respect to the produced polyester. The slurry,
It was charged over 30 minutes and further stirred for 30 minutes. Next, antimony trioxide was added as a polycondensation catalyst in an amount of 0.02 mol% based on the terephthalic acid component, and triethyl phosphate was added as a stabilizer in an amount of 0.05 mol% based on the terephthalic acid component. The temperature was gradually increased from 250 ° C to 280 ° C. The polycondensation reaction was performed while heating and reducing the pressure from normal pressure to a high vacuum of 1.3 hPa or less to obtain polyethylene terephthalate containing fine particles having the characteristics shown in Table 1.

Examples 2 to 6 and Comparative Examples 1 to 6 The same procedures as in Example 1 were carried out except that the conditions were changed as shown in Table 1, to obtain fine particle-containing polyethylene terephthalate having the properties shown in Table 1.

[0035]

[Table 1]

As is clear from Table 1, all of the polyesters obtained in Examples 1 to 6 have few coarse particles.
It was good.

On the other hand, the polyesters obtained in Comparative Examples 1 to 6 had a large number of coarse particles,
The EG content was high. The polyester obtained in Comparative Example 1 had many coarse particles because the viscosity of the esterified product and the EG slurry exceeded 5 dPa · s. The polyester obtained in Comparative Examples 2 and 3 had a viscosity difference between the esterified product and the EG slurry of 1 dPa.
-Since it exceeded s, there were many coarse particles.
In the polyester obtained in Comparative Example 4, the viscosity of the EG slurry exceeded 5 dPa · s, and the esterified product and E
Because the viscosity difference from G slurry exceeded 1 dPa · s,
There were many coarse particles. The polyester obtained in Comparative Example 5 had many coarse particles because the stirring time after adding the EG slurry to the esterified product was less than 10 minutes. The polyester obtained in Comparative Example 6 had a stirring time of 60 hours after adding the EG slurry to the esterified product.
Minutes, the DEG content was high.

[0038]

According to the method of the present invention, it is possible to obtain a polyester having very few coarse particles due to aggregation of inert fine particles. Therefore, if a film is produced using this polyester, the process passability becomes very good, and the obtained film has few coarse projections on the surface, and when used as a base of a magnetic tape, it is desirable that the film has dropouts and the like. High quality with surface characteristics that do not cause any undesired phenomena.

Claims (1)

[Claims] 1. A method for producing an inert fine particle-containing polyester by adding an ethylene glycol slurry of inert fine particles to an esterified product of terephthalic acid and ethylene glycol and performing a polycondensation reaction, wherein the viscosity at 250 ° C. is 5 dPa · s or less, and an ethylene glycol slurry of inert fine particles having a viscosity at 20 ° C. of 5 dPa · s or less is added to the esterified product under conditions that the viscosity difference (absolute value) with the esterified product is 1 dPa · s or less. A method for producing a polyester containing inert fine particles, wherein a polycondensation reaction is carried out until the intrinsic viscosity becomes 0.5 to 1.0 after stirring for 60 minutes.