JP3100730B2 - Polyester production method - Google Patents

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, and more particularly to a method for producing a polyester having excellent transparency as a molded article and excellent melt molding performance.

[0002]

2. Description of the Related Art Polyester is widely used in fibers, films, bottles, industrial resins and the like because of its excellent mechanical, physical and chemical properties.

[0003] In the case of molded articles such as bottles, the transparency of the molded articles is important for reasons of appearance, and polyesters that do not impair the transparency are demanded. The following two factors can be considered as factors that impair transparency. One is the so-called internal haze caused by the catalyst particles, and the other is the non-uniform surface due to the adhesion or transfer of the oligomer to the mold.

Various catalysts have been used for the production of polyester since ancient times. The most widely used are antimony catalysts, which are present as particles in the polymer because of their low solubility in polyesters, and significantly impair the transparency of the molded articles.

On the other hand, since the titanium catalyst has a high solubility in a polymer, the internal haze can be suppressed low.

It is also known that germanium catalysts have relatively high solubility in polymers and the internal haze is not so bad as that of antimony catalysts.

On the other hand, as a method for solving the problem of adhesion of oligomers to a mold and surface unevenness due to transfer, a method of reducing the amount of oligomers containing polyester has been studied and many proposals have been made. For example, a method in which a polyester is heat-treated in a high vacuum state at a temperature lower than its melting point (JP-A-48-10)
1462, JP-A-51-48505), and a method of heat treating polyester at a temperature lower than the melting point in an inert gas atmosphere (JP-A-55-189331). When the oligomer is reduced by these methods, the oligomer is observed as white powder in a region where the amount of oligomer is relatively high, and has an effect of reducing the amount of the white powder itself. Not only can it not be exerted, but on the contrary, white powder may increase.

In connection with these techniques, Japanese Patent Laid-Open Publication No.
No. 8420 proposes a method of reducing the oligomer by partially hydrolyzing a polyester with water, and Japanese Patent Application Laid-Open No. 3-47830 proposes a method of treating polyethylene terephthalate with water in order to reduce the oligomer generated during molding. ing. However, although this method certainly has an effect when germanium is used as a catalyst, it does not have any effect on reducing oligomers generated during molding with respect to polyester produced using an antimony catalyst or a titanium catalyst. Regarding germanium catalysts, transparency is insufficient in fields where the required quality is severe, such as bottles for mineral water. This is because germanium catalysts have high solubility in polymers, but in such fields, more soluble catalysts are desired,
This is probably because the solubility of germanium is insufficient. Therefore, the present inventors have intensively studied to develop a polyester that gives a molded article having good transparency even in a field where the required quality is severe, and surprisingly, by treating the germanium catalyst with a water colloid, the molded article was made transparent. It has been found that the properties are remarkably improved, leading to the present invention.

[0009]

An object of the present invention is to eliminate such problems.
An object of the present invention is to provide a method for producing a polyester having excellent transparency as a molded article.

[0010]

SUMMARY OF THE INVENTION The present invention provides an ethylene fragrance.
With aromatic dicarboxylate as the main repeating unit
A method for producing a stell, comprising:
A step of reducing the trimer content to 0.4% by weight or less,
Aqueous solution containing germanium compound treated with water colloid
A polycondensation reaction by adding
Polyester comprising the step of contacting the ester with water
It is a manufacturing method of.

The present invention will be described.

In the present invention, the "polyester" refers to a polyester containing an aromatic dicarboxylic acid as a main acid component and ethylene glycol as a main glycol component. Here, "main" means that the ethylene aromatic dicarboxylate unit accounts for 85 mol% or more.
What contains 15 mol% or less of the third component is a technique to which the present invention can be applied.

Examples of the "aromatic dicarboxylic acid" constituting the polyester include terephthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylketonedicarboxylic acid, diphenoxyethanedicarboxylic acid and the like.

The "aliphatic glycol" constituting the polyester is ethylene glycol, and other glycols such as tetramethylene glycol have no effect of the present invention.

The copolymerizable third component includes aromatic dicarboxylic acids, dicarboxylic acids other than ethylene glycol, diols, and oxycarboxylic acids which constitute the polyester. Specifically, in addition to the above compounds, aromatic dicarboxylic acids such as isophthalic acid, diphenylsulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, sodium-sulfoisophthalic acid, and dibromoterephthalic acid; alicyclic dicarboxylic acids such as decalin dicarboxylic acid And aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid and sebacic acid. Also,
Examples of the glycol component include aliphatic diols such as trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, diethylene glycol, and triethylene glycol; aromatic diols such as catechol, naphthalene diol, resorcinol and 4,4'- Dihydroxy-diphenyl-sulfone, bisphenol A ([2,2'-bis (4
-Hydroxyphenyl) propane]), tetrabromobisphenol A, bishydroxyethoxybisphenol A, etc .; alicyclic diols, eg, cyclohexanediol; aliphatic oxycarboxylic acids, eg, glycolic acid, hydroacrylic acid, 3-oxypropionic acid, etc. ;
Alicyclic oxycarboxylic acids such as asiatic acid, quinovanic acid and the like; aromatic oxycarboxylic acids such as salicylic acid,
Examples thereof include m-oxybenzoic acid, p-oxybenzoic acid, mandelic acid, and atrolactic acid.

Further, within the range where the polyester is substantially linear, trifunctional or higher polyfunctional compounds such as glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid, promellitic acid, tricarballylic acid, and gallic An acid or the like may be copolymerized, and if necessary, a monofunctional compound such as o-benzoylbenzoic acid or naphthoic acid may be added.

The germanium catalyst used in the present invention is directed to crystalline germanium dioxide which has been treated with a water colloid. The use of mere crystalline germanium dioxide powder or a slurry of ethylene glycol or the like is insufficient in the transparency of the molded article in the field where the required quality is severe.

As the water colloid treatment method, for example, the following method can be exemplified. Crystalline germanium dioxide is dispersed in a large amount of ion-exchanged water so as to have a concentration of about 0.1 to 2% by weight, and is close to the boiling point of water, for example, 80 to 100
C. for several hours, for example, 3 to 10 hours. During the heat treatment, water can be distilled off to adjust the concentration.

The water colloidal germanium dioxide treated by this method has an infrared absorption spectrum of 515,551,
It has absorption at 587, 872 and 955 cm ^-1 , retains a hexagonal crystal state, and is not a hydrate (500,780 cm ^-1 ). And, it exhibits the Tyndall phenomenon which is a characteristic of the aqueous colloid liquid.

The preparation of the polyester of the present invention can be carried out by a generally known method, except that germanium dioxide which has been treated with a water colloid is used as a polymerization catalyst. For example, a method of directly esterifying an acid and a glycol followed by melt polycondensation in the presence of a suitable catalyst, a method of subjecting a lower alkyl ester of an acid to glycol to a transesterification reaction in the presence of a suitable catalyst, and then performing a melt polycondensation And the like. In any case, after the melt polycondensation, the mixture is melt-extruded, cooled in a suitable cooling medium, for example, water, cut into a suitable size, and formed into chips.
The tip may be a rectangular parallelepiped, a cylinder, a die, or a sphere.

According to the present invention, it is essential that the amount of oligomers (especially cyclic trimers) contained in the polyester thus obtained is 0.4 wt% or less. When the amount of the oligomer exceeds 0.4% by weight, the transparency is significantly reduced due to uneven surface of the molded article, which is not preferable.

As a method for reducing oligomers in the polyester, generally known methods such as a solid phase polymerization method, an extraction method and a hydrolysis method can be used.

The contact treatment with water which is carried out subsequent to the oligomer reduction treatment can be carried out by a known method, but the treatment conditions for imparting sufficient transparency to the molded product are preferably 70 to 100 ° C. 3 hours or more.

[0024]

The present invention will be described in more detail with reference to the following examples. In the examples, "parts" indicates parts by weight, and characteristic values are measured by the following methods.

1) Intrinsic viscosity: [η] Calculated from the solution viscosity measured at 35 ° C. using an orthochlorophenol solvent.

2) Transparency of molded article: 160
After drying at 5 ° C. for 5 hours, using an injection molding machine Dynamelter M-100DM manufactured by Meiki Seisakusho, cylinder temperature 29
A 50 g proform is molded at 5 ° C. and blow-stretched to form a bottle having an inner volume of 1.5 liter and a body thickness of 0.3 mm. The straight body was cut out and the haze of the bottle body was measured with a haze meter to determine the transparency of the molded product.

3) Measurement of oligomer (cyclic trimer) A sample was taken from a polymer or a preform of a molded bottle, and this was sampled from hexafluoroisopropanol /
The filtrate was dissolved in a mixed solvent of chloroform (50/50), further diluted with chloroform, and filtered through a Millipore filter, and the content of the cyclic trimer was quantified by ALC / GPC744 manufactured by Waters.

Fogging caused by irregularities on the surface of the bottle due to transfer of the deposits on the bottle to the bottle cannot be evaluated without continuous molding for a long period of time.

[0029]

Example 1 1700 parts of dimethyl terephthalate, 1100 parts of ethylene glycol, 1.3 parts of an ethylene glycol solution of titanium acetate (1% as Ti), and 4.9 parts of diethylene glycol were charged into a transesterification reaction tank.
A transesterification reaction was performed at ２235 ° C. At the time when no distillate was generated, 42 parts of “water colloid Ge” described below was added to an ethylene glycol solution of methyl amide phosphate (P
1.5%) was transferred to the polymerization reactor. The reaction was carried out at 260 to 270 ° C for about 30 minutes under normal pressure, and then the reaction was carried out at 265 ° C under high vacuum (high vacuum of several mmHg or more) for about 2 hours. Thereafter, a large amount of running water was withdrawn from the polymerization reactor by a conventional method to obtain a strand type chip. [Η] of this chip was 0.53. After pre-drying the chips at 150 to 160 ° C. for about 3 hours,
Solid phase polymerization was performed at 230 ° C. for 10 hours under a high vacuum of mmHg.
[Η] of the chip after the solid phase polymerization was 0.77, and the oligomer in the chip was 0.26 wt%.

1 kg of the chip was placed in a 5 liter processing apparatus containing 2.5 kg of water at a temperature of 90 ° C., and the temperature was raised to 90 ° C.
The contact was maintained for 4 hours while maintaining the temperature. 160 after removing water
It was dried under a nitrogen stream at 5 ° C. for 5 hours. [Η] of the chip after the treatment was 0.76, and the amount of the oligomer was 0.26 wt%.

[0031] 0.6% when measured haze by molding the bottle in the manner described above from the chip, the cage <br/> Goma amount was 0.28 wt%.

The “water colloid germanium” used as the polymerization catalyst is as follows. Crystalline germanium dioxide powder was mixed in pure water at a concentration of 0.6% by weight, and the mixture was stirred at 100 ° C. for 6 hours and boiled under circulation. A liquid of 0.76% by weight was obtained.

The infrared absorption spectrum of this was 515,
Has absorption at 551, 587, 872 and 955 cm ^-1 ,
A typical hexagonal crystalline germanium dioxide pattern is shown. However, although the appearance of the liquid was transparent and no particles were observed, it was extremely thin milky white and showed the Tyndall phenomenon, and it was found that the crystals were refined to a colloidal state (hereinafter referred to as "water colloid"). Ge (germanium) ").

[0034]

Comparative Example 1 Example 1 was repeated except that “slurry Ge” was used as a polymerization catalyst and the amount added was 1.6 parts.
The same processing as described above was performed. The "slurry Ge" refers to a dispersion of crystalline germanium dioxide powder in ethylene glycol as it is so as to have a concentration of 20% by weight and a sand grinder treatment to obtain a germanium dioxide ethylene glycol slurry. 6 μm (hereinafter referred to as “slurry Ge”).

[0035]

Comparative Example 2 The same treatment as in Example 1 was carried out except that "powder Ge" was used as the polymerization catalyst and the amount added was 0.3 part. The term “powder Ge” refers to powdered germanium dioxide (hereinafter referred to as “powder G”).
e)).

[0036]

Comparative Example 3 1.3 wt% of Sb ₂ O ₃ as a polymerization catalyst
The same treatment as in Example 1 was performed except that 53 parts of ethylene glycol slurry was used.

[0037]

Comparative Example 4 The same treatment as in Example 1 was carried out except that 4.3 parts of an ethylene glycol solution of titanium acetate (1% as Ti) was additionally used as a polymerization catalyst.

[0038]

Example 2 and Comparative Examples 5 and 6 The same treatment as in Example 1 was performed except that the water contact conditions were changed.

[0039]

Comparative Example 7 The same treatment as in Example 1 was performed except that the water contact treatment was omitted.

[0040]

Comparative Example 8 The melt polymerization was carried out for about 3 hours, and [η] 0.
After the polyester of No. 65 was obtained, the same treatment as in Example 1 was performed except that the solid phase polymerization was performed for 5 hours. The amount of oligomer contained in the chip after solid-phase polymerization was 0.60 wt%.
Met.

The above experimental results are summarized in Tables 1 and 2.

[0042]

[Table 1]

[0043]

[Table 2]

[0044]

The polyester according to the method of the present invention has a low internal haze of the polymer, a small amount of oligomer adhered to the drum or the mold even when melt-molded for a long time, and has excellent transparency because the surface of the molded product is kept uniform. A molded article is obtained.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-3-72524 (JP, A) JP-B-46-42492 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 63/00-63/91

Claims (2)

(57) [Claims] 1. A method for producing a polyester containing ethylene aromatic dicarboxylate as a main repeating unit, comprising the step of reducing the cyclic trimer content of the polyester to 0.4% by weight or less, a water colloid treatment. A polycondensation reaction by adding an aqueous solution containing the obtained germanium compound as a catalyst, and a step of bringing the polyester into contact with water. 2. The condition for bringing the polyester into contact with water is at least 70 ° C. for at least 3 hours.
The method for producing a polyester according to the above.