JPH05339357A - Production of polyester - Google Patents

Abstract

PURPOSE:To improve the clarity and resistance to crazing of a melt-molded plyester article. CONSTITUTION:A polyester having an intrinsic viscosity of 0.8-0.9 is produced by using a titanium tetraalkoxide treated with an org. carboxylic acid as a transesterification catalyst, orthophosphoric acid as a stabilizer, and a crystalline germanium dioxide treated with an aq. colloid as a polycondensation catalyst while allowing diethylene glycol to be produced as a by-product during the reaction.

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 suitable for a bottle application, especially for a self-standing pressure vessel.

[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.

The bottles range from those for which internal pressure is not applied, such as those for detergents, soy sauce, and juices, to those for which internal pressure is applied, such as carbonated drinks.

The latter bottle, which is subjected to internal pressure, has a design with a rounded bottom in order to provide the bottle with strength, but it cannot be placed upright as it is, so-called two piece with a hakama attached to the bottom. There are many mold bottles.

However, from the viewpoint of resource saving or cost reduction, a petaloid type self-standing bottle (two-piece type) is devised by devising the shape of the bottom without using a hakama of a different material or an adhesive for attaching it to the bottle body. Bottle) is required.

When the bottom of a bottle to which stretch orientation is not applied so much has a complicated shape, the internal pressure increases, and when it is placed in contact with a liquid, the strained portion cracks, a so-called crazing phenomenon. Is likely to appear and crazing often causes bottle breakage.

As a method of preventing this, a method of increasing the polymerization degree of the polymer is generally used.

[0008]

In the case of the polyester produced by the transesterification method, the degree of polymerization (depolymerization) and the deterioration of fluidity due to melt molding occur due to the residual catalyst metal, and the crystallinity also increases. There is a problem that the preform is liable to be whitened and the preform is whitened.

The present inventors have arrived at the present invention as a result of earnest studies on the production of polyester suitable for a self-standing bottle having excellent transparency while solving the problem of whitening and improving the crazing resistance. ..

[0010]

That is, according to the present invention, when a polyester is produced by a transesterification method using an organic titanium compound as a transesterification catalyst, (1) titanium tetraalkoxide is used as an organic titanium compound with an organic carboxylic acid. What was treated, (2) orthophosphoric acid as a stabilizer, and (3) hydrocolloid-treated crystalline germanium dioxide as a polycondensation catalyst were used to produce a small amount of diethylene glycol as a by-product during the reaction, and the intrinsic viscosity was 0. ．
It is a method for producing a polyester, which is characterized by carrying out a polycondensation reaction until reaching 8 to 0.9.

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. Here, "mainly" means that ethylene aromatic dicarboxylate units account for 95 mol% or more.
A technique containing 5 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 "glycol" constituting the polyester is an alkylene glycol,
Especially ethylene glycol.

As the copolymerizable third component, aromatic dicarboxylic acids constituting the polyester, dicarboxylic acids other than ethylene glycol and ether glycol,
There are diols and oxycarboxylic acids. 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, etc .; alicyclic dicarboxylic acids such as decalin dicarboxylic acid. , Tetralindicarboxylic acid, hexahydroterephthalic acid and the like; aliphatic dicarboxylic acids such as malonic acid, succinic acid, adipic acid and sebacic acid. Examples of the glycol component include aliphatic diols such as trimethylene glycol, tetramethylene glycol, pentamethylene glycol and hexamethylene glycol; aromatic diols such as catechol, naphthalene diol, resorcin, 4,4'-dihydroxy-diphenyl-sulfone. , Bisphenol A
([2,2'-bis (4-hydroxyphenyl) propane]), tetrabromobisphenol A, etc .; alicyclic diols, such as cyclohexanediol; aliphatic oxycarboxylic acids, such as glycolic acid, hydroacrylic acid, 3- Oxypropionic acid, etc .; alicyclic oxycarboxylic acid, such as asiatic acid, quinobaic acid, etc .; aromatic oxycarboxylic acid, such as salicylic acid, m-oxybenzoic acid, p-oxybenzoic acid, mandelic acid, atrolactic acid, etc. be able to.

Furthermore, within the range in which 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, monofunctional compounds such as o-benzoylbenzoic acid and naphthoic acid. May be added.

The polyester in the present invention is limited to the production method by the transesterification method.

Suitable as transesterification catalysts are organic titanium compounds, especially titanium tetraalkoxides treated with organic carboxylic acids. The reason for using the organic titanium compound is that it has good solubility in the polymer and the obtained polymer has excellent transparency. However, even if it is a titanium compound, when titanium tetraalkoxide is used as it is, when a polymer is melt-molded, abnormal flow is likely to occur when high shear is applied. When treated with an organic carboxylic acid, abnormal polymer flow is significantly alleviated, the selection range of molding conditions is expanded, and whitening of preforms and fogging of bottles are improved.

Organic carboxylic acids for treating titanium tetraalkoxide include monocarboxylic acids such as formic acid, acetic acid, propionic acid, stearic acid, palmitic acid; polycarboxylic acids such as oxalic acid and succinic acid.
Malonic acid, phthalic acid, trimellitic acid, trimesic acid,
Pyromellitic acid etc. are illustrated.

If the length of the aliphatic molecule becomes long or the carbon number of the carboxylic acid becomes large, the reaction of blocking the titanium compound becomes slow and the effect may be lowered. Acetic acid is most preferred.

The amount of the treated titanium catalyst used is not particularly limited, but is usually 1 to 10 mmol%, preferably 2 to 5 mmol% as titanium metal based on the total acid components constituting the polyester.

Orthophosphoric acid is used as the stabilizer. Less effective with phosphorous acid, (sub) phosphonic acid, and (sub) phosphinic acid. Even if it is orthophosphoric acid, it must not be a half ester or a triester. For the first time, orthophosphoric acid can successfully deactivate the catalytic activity by the interaction with the organotitanium compound, stabilize the polymer, and reduce abnormal flow of the polymer. The amount of orthophosphoric acid used is usually preferably 3 to 40 mmol%, particularly preferably 5 to 20 mmol%, based on the total acid components constituting the polyester.

Further, the phosphorus / titanium molar ratio is preferably in the range of 2 to 10, and particularly preferably 2.5 to 5. In the case of ordinary transesterification catalysts, the phosphorus / catalyst molar ratio is around 1, whereas in the case of the present invention it is 2 or more.
However, if the amount is too large, a large amount of phosphorus that does not interact with the titanium catalyst is present in the polymer, which rather deteriorates the thermal stability of the polymer.

As the polymerization catalyst, crystalline germanium dioxide treated with water colloid is used. The transparency of the polymer is poor when used as a mere crystalline germanium dioxide powder or in a slurry state of ethylene glycol or the like.

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 as to have a concentration of about 0.1 to 1 wt%, and is near the boiling point of water, for example, 80 to 100.
Heat treatment is performed at a temperature of several degrees Celsius for several hours, for example, 3 to 10 hours. It is also possible to distill water during the heat treatment to adjust the concentration.

The hydrocolloidal germanium dioxide treated by the method of the present invention has an infrared absorption spectrum of 515,55.
There is absorption at 1,587,872,955 cm ^-1 , and the hexagonal crystalline state before treatment is maintained, and the hydrate (500,
It is not in the state of 780 cm ^-1 ). Then, it exhibits the Tyndall phenomenon, which is a characteristic of hydrocolloid solutions.

The polyester of the present invention is a by-product of diethylene glycol during the production of the polymer. The amount of by-product is preferably 1.5 to 2.2% by weight based on the polymer.
If it is too small, sufficient flow cannot be secured, and if it is too large, the thermal stability of the polymer decreases.

The polymer of the present invention can be produced by a generally known method except that the above-mentioned various conditions are satisfied.

After melt polycondensation, melt extrusion is carried out, and a suitable refrigerant,
For example, it is cooled in water, cut into an appropriate size, and made into chips. The chips may have a rectangular parallelepiped shape, a cylindrical shape, or a dice shape.

The polyester of the present invention can be further subjected to solid phase polymerization at a temperature below the melting point depending on the purpose to reduce the amount of oligomers in the polymer. Moreover, the effect of the method of the present invention becomes more prominent when the polymer has a lower oligomer content.

The solid phase polymerization may be carried out under an inert gas flow or under vacuum (under reduced pressure), and may be applied in a continuous system or a batch system. Further, it may be a packed tower type, a horizontal clinker type, or a tumbler type.

The polyester of the present invention is subjected to a polycondensation reaction until the intrinsic viscosity finally becomes 0.8 or more and 0.9 or less. If the intrinsic viscosity is less than 0.8, crazing will occur after a long time when the petaloid type bottom surface is used,
When it exceeds 0.9, the polymer fluidity at the time of melt molding is deteriorated and the bottle is fogged even if the catalyst stabilizer and the like are used under the above-mentioned conditions.

The polyester obtained by the method of the present invention is suitable for a self-standing bottle having a petaloid bottom and is excellent in transparency and crazing resistance.

[0032]

EXAMPLES The present invention will be supplemented by the following examples. In addition, "part" in an implementation collar means a weight part. Moreover, the measuring method of the characteristic used in the Example is shown below.

1) Intrinsic viscosity: [η] phenol / tetrachloroethane (weight ratio 60/40)
It was calculated from the solution viscosity measured at 35 ° C. using the mixed solvent of.

2) Transparency of molded product After drying the polymer at 160 ° C. for 5 hours, an injection molding machine Dynamelter M-100DM manufactured by Meiki Seisakusho was used.
50 g of a preform is molded at a cylinder temperature of 295 ° C. and blow-stretched to obtain a petaloid-bottomed bottle having an internal volume of 1.5 liters and a body thickness of 0.3 mm. The straight body was cut off, and the haze of the bottle body was measured with a haze meter to determine the transparency of the molded product.

3) Crazing property The above bottle was filled with an 8% aqueous acetic acid solution, and the mixture was sealed with carbon dioxide at 3.5 vol and sealed at 50 ° C. for 1 month to examine whether crazing occurred.

[0036]

Reference Example 1 Crystalline germanium dioxide powder was directly dispersed in ethylene glycol so as to be 20% by weight and subjected to a sand grinder to obtain a germanium dioxide ethylene glycol slurry. Typical particle size is 4-6
μm (hereinafter referred to as “slurry Ge”).

[0037]

[Reference Example 2] (Water colloid treatment) Crystalline germanium dioxide powder was blended in pure water so as to be 0.6% by weight, and 100% of this was added.
After stirring at ℃ for 6 hours and boiling under circulation, a part of water was distilled off to finally obtain a 0.76 wt% liquid.

The infrared absorption spectrum of this product is 515,
551,587,872,955 cm ^-1Has absorption in
Typical hexagonal crystalline germanium dioxide pattern
Indicated. However, the appearance of the liquid is transparent and no particles are observed.
However, it is extremely pale milky white and exhibits the Tyndall phenomenon.
Therefore, it is possible that the crystals are miniaturized to a colloidal state.
It was understood (hereinafter referred to as "hydrocolloid Ge"). Na
The powdered crystalline germanium dioxide as it is
It is called "powder Ge".

[0039]

[Reference Example 3] Titanium tetrabutoxide 17.8
Parts, and 12.6 parts of acetic acid are mixed with 220 parts of ethylene glycol and stirred at 60 ° C. for 30 minutes. This solution contains a titanium compound as titanium metal in an amount of 1.0% by weight (hereinafter referred to as "titanium acetate").

[0040]

[Reference Example 4] 3.47 parts of titanium tetrabutoxide,
3.92 parts of trimellitic anhydride were replaced with ethylene glycol 4
It is mixed with 1 part and reacted at 160 to 177 ° C. for 120 minutes to distill 0.6 parts of butanol produced as a result of the reaction. In this solution, a titanium compound was used as titanium metal.
The content is 0% by weight (hereinafter, this is referred to as "titanium trimellitate").

[0041]

Examples 1 to 8 and Comparative Examples 1 to 8 20000 parts dimethyl terephthalate, 12780 parts ethylene glycol, Table 1
The various titanium compounds shown in Fig. 3 were added to an autoclave equipped with a stirrer at a concentration of 3.5 mmol% as titanium metal at 240 ° C.
It was made to react with. When approximately the theoretical amount of methanol was distilled, various phosphorus compounds shown in Table 1 were added, and then 30 mmol% of various germanium compounds shown in Table 1 were added as germanium to carry out polycondensation reaction at 270 ° C. under reduced pressure. It was At this time, the amount of diethylene glycol produced as a by-product was controlled by changing the normal pressure reaction time in the initial stage of polymerization. After melt-polymerizing to an intrinsic viscosity of 0.65, chip it into 22
Solid-state polymerization was carried out at 0 ° C. in an inert gas stream to various intrinsic viscosities shown in Table 1.

The polymer obtained was molded into a preform at 295 ° C. and then molded into a bottle having a petaloid bottom of 1.5 liters. The quality of the molded product is shown in the right column of Table 1.

[0043]

[Table 1]

Claims (2)

[Claims] 1. When a polyester is produced by a transesterification method using an organic titanium compound as a transesterification catalyst, (1) a titanium tetraalkoxide treated as an organic titanium compound with an organic carboxylic acid,
(2) Orthophosphoric acid as a stabilizer, and (3) hydrocolloid-treated crystalline germanium dioxide as a polycondensation catalyst are used, a small amount of diethylene glycol is produced as a by-product during the reaction, and the intrinsic viscosity is 0.8 to 0. A method for producing a polyester, which comprises subjecting the polyester to a polycondensation reaction until it becomes 9. 2. The organic titanium compound according to claim 1, wherein the amount of the organic titanium compound is 1 to 10 mmol% as titanium metal, and the amount of orthophosphoric acid is 3 to 4 with respect to the total acid components constituting the polyester.
A method for producing a polyester, wherein the amount of diethylene glycol by-produced is 0. 5% by weight based on the polymer, and the molar ratio of phosphorus / titanium is 2-10.