JPH05230194A - Production of polyester - Google Patents

Abstract

PURPOSE:To improve transparency of melt molding of polyethylene aromatic dicarboxylate. CONSTITUTION:In polymerizing ethylene glycol with an aromatic dicarboxylic acid or its functional derivative, the monomers are subjected to polycondensation by using crystalline germanium dioxide subjected to water colloid treatment as a catalyst and the prepared polymer is humidified to give a polyster.

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 technique for producing a polyester having excellent transparency and high molding performance.

[0002]

BACKGROUND OF THE INVENTION Polyester is widely used for packaging materials such as fibers, films and bottles, and industrial resins because it has excellent mechanical, physical and chemical properties.

[0003] Among them, in recent years, the expansion of packaging materials centering on bottles has been remarkable, and the required characteristics have become more severe. In particular, recently, from the viewpoint of improving the appearance of molded products, there is a strong demand for polyesters having higher transparency and high productivity, that is, excellent moldability performance. There are two main factors that influence the transparency. The first is a problem of haze inside the molded product, and the second is an optical problem caused by irregular reflection of light due to irregularities on the surface of the molded product and adhesion of white powder. Regarding the former, the polymerization catalyst mainly used for polyester has a great influence. A commonly used antimony compound catalyst has low solubility in a polymer and has a high internal haze (poor transparency) because it exists as particles in the polymer. On the other hand, although the titanium catalyst has high solubility in the polymer and excellent transparency, it has a strong activity and is apt to promote the decomposition reaction, and thus has a problem of a decrease in polymerization degree and a coloring problem. On the other hand, the germanium catalyst does not have such a large activity and a large amount of it has to be used, but it has a relatively good solubility in the polymer and a polymer having a considerably high transparency can be obtained. However, its transparency is inferior to that of titanium catalysts, and it has not reached the current strict requirements. On the other hand, for the latter, the oligomer mainly contained in the polyester is the main cause, and during the stretching and heat setting steps during molding, this oligomer bleeds out on the surface and adheres to the mold by long-term continuous molding and accumulates. By doing so, unevenness is generated on the surface of the molded product. Therefore, as a countermeasure against this, a technique such as solid phase polymerization has been conventionally used for the purpose of reducing the content of oligomers in the polyester, and actually, some effect has been achieved. However, even if the absolute value of the oligomer is lowered in this way, the effect is halved because the oligomer is regenerated during melting at the time of molding, and in fact, the level cannot be sufficiently satisfied. However, recently, as a method of suppressing the regenerated oligomer at the time of melting, it has been proposed to once treat the chips with water. [JP-A-3-47830, JP-A-3-47830
No. 174441, etc.]. This is because the polymerization catalyst contained in polyester is deactivated by water treatment, and the effect suppresses the regeneration of oligomers during melting. There is no known difference.

As a result of a detailed study by the present inventors, in practice, generally used antimony catalysts and titanium catalysts have almost no effect of suppressing the regeneration of oligomers, and also in the germanium catalyst,
It was found that the effect is exhibited only when certain conditions are satisfied.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made earnest studies, and as a result, in the polymerization of polyester, a germanium catalyst subjected to a specific pretreatment was used, and the obtained polymer was further conditioned to obtain a specific content. By setting the moisture content,
The inventors have found that the problems of internal haze, surface smoothness, and adhesion of white powder as described above can be solved at the same time, a molded article with extremely high transparency can be obtained, and molding performance can be improved, and the present invention has been completed.

[0006]

The present invention provides one of polycondensation catalysts for producing a polyester whose main repeating unit is ethylene aromatic dicarboxylate,
At least oligomers (cyclic trimers) contained in polycondensation reaction using a germanium compound treated with water colloid
Of 0.4% by weight or less is obtained, and then the moisture content of the polyester is adjusted to 0.4 to 0.8% by weight, thereby producing a polyester.

The present invention will be described.

In the present invention, "polyester" means a polyester having an aromatic dicarboxylic acid as a main acid component and ethylene glycol as a main glycol component. As used herein, "mainly" means that ethylene aromatic dicarboxylate units account for 85 mol% or more.
A technique containing 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 and diphenoxyethanedicarboxylic acid.

The "aliphatic glycol" constituting the polyester is specified as ethylene glycol. The effect of the present invention does not appear with tetramethylene glycol and others.

The third component which can be copolymerized is an aromatic dicarboxylic acid constituting the polyester, a dicarboxylic acid other than ethylene glycol, a diol and an oxycarboxylic acid. Specifically, in addition to the above compounds, aromatic dicarboxylic acids such as isophthalic acid, diphenylsulfone dicarboxylic acid, diphenyl ketone dicarboxylic acid, sodium-sulfoisophthalic acid, dibromoterephthalic acid; alicyclic dicarboxylic acids such as decalin dicarboxylic acid. Examples thereof include acids, tetralindicarboxylic acid, hexahydroterephthalic acid and the like; aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid and sebacic acid. As the glycol component, an aliphatic diol such as trimethylene glycol, tetramethylene glycol,
Pentamethylene glycol, hexamethylene glycol, diethylene glycol, triethylene glycol, etc .; aromatic diols such as catechol, naphthalene diol, resorcin, 4,4'-dihydroxy-diphenyl-sulfone, bisphenol A ([2,2'-bis ( 4-hydroxyphenyl) propane]), tetrabromobisphenol A, bishydroxyethoxybisphenol A, etc .; alicyclic diols such as cyclohexanediol; aliphatic oxycarboxylic acids such as glycolic acid, hydroacrylic acid, 3-oxypropionic acid Alicyclic oxycarboxylic acids such as asiatic acid, quinobaic acid and the like; aromatic oxycarboxylic acids such as salicylic acid, m-oxybenzoic acid, p-oxybenzoic acid, mandelic acid, atto Or the like can be mentioned Rakuchin acid.

Further, within the range where the polyester is substantially linear, a polyfunctional compound having a valence of 3 or more, such as glycerin, trimethylolpropane, pentaerythritol,
Trimellitic acid, trimesic acid, pyromellitic acid, tricarballylic acid, gallic acid and the like may be copolymerized, and if necessary, a monofunctional compound such as o-benzoylbenzoic acid,
Naphthoic acid or the like may be added.

The germanium catalyst used in the present invention is intended for crystalline germanium dioxide treated with hydrocolloid. Solubility in the polymer was not sufficiently satisfied with the mere use of crystalline germanium dioxide powder or a slurry state such as ethylene glycol, or the hydrate of germanium dioxide (or germanium hydroxide) Poor polymer transparency.

Examples of the water colloid treatment method include the following methods. Crystalline germanium dioxide is dispersed in a large amount of ion-exchanged water so that the concentration is about 0.1 to 2 wt%, and heat treatment is performed at a temperature close to the boiling point of water, for example, at 80 to 100 ° C. for several hours, for example, 3 to 10 hours. During the heat treatment, the concentration can be adjusted by distilling water.

The water colloidal germanium dioxide treated by this method has infrared absorption spectra of 515, 551 and 87.
It has absorptions of 2 and 955 cm ^-1 , maintains a hexagonal crystalline state, and is not a hydrate (500, 780 cm ^-1 ). Then, it exhibits the Tyndall phenomenon, which is a characteristic of hydrocolloid liquids.

The polyester can be produced by a generally known method except that hydrocolloid-treated germanium dioxide is used as a polymerization catalyst.

For example, a method in which an acid and a glycol are directly esterified and then melt polycondensed in the presence of a suitable catalyst, or a lower alkyl ester of an acid and a glycol are subjected to transesterification reaction in the presence of a suitable catalyst, Examples thereof include a method of melt polycondensation. In either case, after melt polycondensation, melt extrusion is performed, followed by cooling in a suitable cooling medium such as water, cutting into a suitable size, and chipping. The chips may be rectangular parallelepiped, cylindrical, dice or spherical.

Further, in the polyester of the present invention, the oligomer content should be 0.4% by weight or less. This is because, as described above, the oligomer mainly causes the deterioration of the smoothness of the molding surface and the white powder, which deteriorates the transparency. The means for reducing the oligomer content is not particularly limited, and includes, for example, solid phase polymerization method, extraction method,
The hydrolysis method [JP-A-56-118420] and the like can be mentioned, but it is generally preferable to use solid phase polymerization from the viewpoints of industrial property, cost performance and quality control.

Next, the chips of the polyester thus obtained having an oligomer content of 0.4% by weight or less are conditioned. As a humidity control means, a high temperature and high humidity atmosphere is preferable from the viewpoint of chip handling property and hydrolyzability after treatment. In this case, the humidity control condition is preferably 80 to 100% relative humidity from the viewpoint of achieving the desired water absorption rate and production efficiency. Further, in order to obtain a sufficient oligomer regeneration suppressing effect, the moisture content in the chip after humidity adjustment is 0.4
It is necessary to keep it to 0.8 wt%. If the water content is less than 0.4 wt%, the effect is not sufficiently obtained and the transparency is poor. Even if the water content exceeds 0.8 wt%, no further improvement in transparency can be expected, and conversely it causes a loss in processing time, resulting in poor production efficiency and in the case of high temperature processing. Promotes hydrolysis and results in poor quality.

[0020]

The present invention will be described in more detail with reference to the following examples. In addition, "part" in an example shows a weight part, and the characteristic value was measured by the following method.

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

2) Moisture content Immediately after the humidity control, the water adhering to the surface of the obtained polymer chip was quickly and completely removed by compressed air, and 50 g of the chip was dried in a dryer at 160 ° x 16h, and the weight loss before and after the drying was measured. Calculated.

3) Transparency of molded product After drying the polymer at 160 ° C. for 5 hours, 50 g of preform was molded at a cylinder temperature of 295 ° C. using an injection molding machine Dynamelter M-100DM manufactured by Meiki Seisakusho, This is blow-drawn and processed into a bottle having an internal volume of 1.5 liters and a body thickness of 0.3 mm. This 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.

4) Oligomer (abbreviated as cy-3) A polymer or a preform of a molded bottle was sampled, dissolved in a fluoroisopropanol / chloroform (50/50) mixed solvent, further diluted with chloroform, and a Millipore filter was used. The content of the cyclic trimer in the filtered filtrate was quantified by ALC / GPC744 manufactured by Waters.

The haze caused by the unevenness of the bottle surface caused by the transfer of the deposit on the mold to the bottle cannot be evaluated unless it is continuously molded for a long period of time. Therefore, the amount of oligomer before and after molding was used as a substitute.

[0026]

[Reference Example 1] Crystalline germanium dioxide powder was directly dispersed in ethylene glycol to a concentration of 20% by weight,
A sand grinder treatment was performed to obtain an ethylene glycol slurry of germanium dioxide. Typical particle size is 4-6 μm
(Hereinafter referred to as "slurry Ge").

[0027]

[Reference Example 2] (Hydrocolloid treatment) 0.6% by weight of crystalline germanium dioxide powder in pure water
The resulting mixture was mixed at 100 ° C. for 6 hours and boiled under circulation, and then a portion of water was distilled off to finally obtain a 0.76% by weight liquid.

The infrared absorption spectrum of this product was 515,
It had absorptions at 551, 587, 872 and 955 cm ⁻¹ and exhibited a typical hexagonal crystalline germanium dioxide pattern. However, the appearance of the liquid was transparent and no particles were observed, but it was extremely pale milky white and exhibited the Tyndall phenomenon, and it was found that the crystals were micronized to a colloidal state (hereinafter referred to as “hydrocolloid Ge”). ")). still,
The crystalline germanium dioxide powder as it is is hereinafter referred to as “powder Ge”.

[0029]

Example 1 1700 parts of dimethyl terephthalate, 1100 parts of ethylene glycol, 1.3% of ethyl acetate solution of titanium acetate (1% as Ti), and 4.9 parts of diethylene glycol were charged into a transesterification reaction tank 170
The transesterification reaction was carried out at ° -235 °. When the distillate is no longer produced, the "water colloid Ge" of Reference Example 2
Part (concentration 0.76 wt%), an ethylene glycol solution of methyl amide phosphate (5.5% as P)
5 parts was added and the mixture was transferred to a polymerization reaction tank. The reaction was performed at 260 to 270 ° C. for about 30 minutes under normal pressure, and then at 265 ° C. under high vacuum (high vacuum of several mmHg or more) for about 2 hours. After that, a strand type chip was obtained by extracting it from a polymerization reaction tank into a large amount of running water by a conventional method. [Η] of this chip was 0.53. The chips are pre-dried at 150 to 160 ° C. for about 3 hours and then 230 mm under a high vacuum of 0.5 mmHg.
Solid phase polymerization was carried out at 10 ° C. for 10 hours. The chip [η] after the solid-state polymerization was 0.77, and the oligomer in the chip was 0.
It was 26 wt%.

3 kg of this chip was placed in a thermo-hygrostat controlled at 90 ° C. × 95% RH and left to stand for 48 hours to adjust the humidity. The treated chip [η] was 0.76, and the oligomer amount was 0.26 wt%.

The chips were melt-molded. Table 1 shows various properties of the molded product.

[0032]

Comparative Example 1 The same process as in Example 1 was carried out except that 1.6 parts (concentration: 20 wt%) of "slurry Ge" was used as a polymerization catalyst.

[0033]

Comparative Example 2 The same treatment as in Example 1 was carried out except that 0.3 part of "powder Ge" was used as a polymerization catalyst.

[0034]

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

[0035]

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 further added instead of the germanium compound as a polymerization catalyst. Similarly, Table 1 also shows the moisture content of chips, [η], and various characteristics of molded products after the conditioning of Comparative Examples 1 to 4.

[0036]

Examples 2 to 3 and Comparative Examples 5 to 6 The procedure is the same as in Example 1 except that the amount of oligomer in the polymer and the humidity control conditions are as shown in Table 1, and the various properties of the molded product are also shown in Table 1. It was shown to.

The results of the above measurements are summarized in Table 1.

[0038]

[Table 1]

[0039]

As described above, the polyester according to the present invention has a low internal haze of the polymer, and even if it is melt-molded for a long period of time, the oligomer is hardly attached to the drum or the mold,
Since diffused reflection does not occur from the surface of the molded product, a molded product with excellent transparency can be obtained.

[Procedure amendment]

[Submission date] January 28, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Examples of the water colloid treatment method include the following methods. Crystalline germanium dioxide is dispersed in a large amount of ion-exchanged water so that the concentration is about 0.1 to 2 wt%, and heat treatment is performed at a temperature close to the boiling point of water, for example, at 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.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

[0027]

[Reference Example 2] (hydrocolloid treatment) 0.6% by weight of crystalline germanium dioxide powder in pure water
The resulting mixture was mixed at 100 ° C. for 6 hours and boiled under circulation, and then a portion of water was distilled off to finally obtain a 0.76% by weight liquid.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction content]

[0038]

[Table 1]

Claims (2)

[Claims] 1. When producing a polyester whose main repeating unit is ethylene aromatic dicarboxylate, a polycondensation reaction is carried out using at least a hydrocolloid-treated germanium compound as one of polycondensation catalysts,
A process for producing a polyester in which the content of the cyclic trimer oligomer is 0.4% by weight or less and the moisture content of the polyester is adjusted to 0.4 to 0.8% by weight. 2. The method for producing a polyester according to claim 1, which comprises subjecting the polyester to a humidity control treatment in an atmosphere having a relative humidity of 80 to 100%.