JP3365679B2 - Method for producing polyester molded product - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyester molded article and a polyester molded article, and more particularly to a method for producing a polyester molded article which gives a polyester having an extremely low formaldehyde content, and an extremely high formaldehyde content. It relates to low polyester moldings.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION Bottles obtained by biaxially stretch-molding saturated polyester such as polyethylene terephthalate are excellent in transparency, mechanical strength, heat resistance and gas barrier property, and can be used for juices, soft drinks, carbonated drinks, etc. It is widely used as a beverage filling container (PET bottle).

Such polyesters are obtained by liquid-phase polycondensation of dicarboxylic acid or its ester-forming derivative with dihydroxy compound or its ester-forming derivative,
It can then be obtained by solid phase polycondensation followed by drying in air or under nitrogen and the like. Since this polyester contains a water content of close to 1% in the atmosphere, it is usually dried in air or nitrogen before molding and then formed into various molded products such as bottles and sheets by various molding methods. It is generally molded.

However, since the nitrogen used for such drying contains impurities, especially oxygen, the conventionally known polyester molded product obtained by the above-mentioned production method contains formaldehyde. . For example, when the molded product is a bottle, the use of such a bottle significantly deteriorates the taste of the contents to be filled.
Therefore, it is desirable that the content of formaldehyde in the polyester forming the molded product is as low as possible.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and provides a method for producing a molded article of a polyester molded article, which allows a polyester molded article having an extremely low formaldehyde content to be obtained. In addition to the above, it aims to provide a polyester molded product having an extremely low formaldehyde content.

[0006]

SUMMARY OF THE INVENTION In the method for producing a polyester molded article according to the present invention, (A) a dicarboxylic acid containing terephthalic acid or an ester derivative thereof and a dihydroxy compound containing ethylene glycol or an ester derivative thereof are present in the presence of a polycondensation catalyst. A liquid phase polycondensation step of producing a polyester (a) by liquid phase polycondensation below, and (C) the polyester (a) is heated to a temperature not higher than the melting point in an inert gas atmosphere to obtain o-chlorophenol. Viscosity [η] measured in
Solid phase polycondensation step for producing a polyester (b) having a ratio of 0.5 to 1.4 dl / g, and (D) drying the polyester (b) in an inert gas atmosphere having an oxygen concentration of 20 ppm or less. The polyester obtained by a production process including a drying process is molded by injection molding or extrusion molding to produce a molded product having a formaldehyde content of 1.0 ppm or less.

In the present invention, prior to the solid phase polycondensation of the polyester (a), the polyester (a) is heated to a temperature above the elevated temperature crystallization temperature (Tc ₁ ) and below the melting point.
You may perform the pre-crystallization process (B) hold | maintained for 30 minutes.

In the present invention, the content of isophthalic acid in the dicarboxylic acid is 0 to 10 mol%, and the content of diethylene glycol in the dihydroxy compound is 0 to 1
0 mol%, cyclohexanedimethanol content 0
It is preferably 10 mol%.

In the present invention, the oxygen concentration in the inert gas atmosphere in the drying step (D) is preferably 20 ppm or less, the drying temperature is preferably in the range of 120 to 180 ° C., and the drying time is 2 It is desirable to be in the range of -24 hours.

The polyester molded product according to the present invention has an intrinsic viscosity [η] of 0.5 measured in o-chlorophenol.
A molded article obtained by molding a polyester in the range of ~ 1.4 dl / g by injection molding or extrusion molding,
It is characterized in that the formaldehyde content is 1.0 ppm or less. Such a polyester molded article,
For example, it is obtained by the manufacturing method described above.

The polyester molded product of the present invention is preferably a bottle-forming preform, a bottle, a sheet or the like.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The method for producing a polyester molded article and the polyester molded article according to the present invention will be specifically described below.

The method for producing a polyester molded article according to the present invention comprises (A) a dicarboxylic acid containing terephthalic acid or an ester derivative thereof and a dihydroxy compound containing ethylene glycol or an ester derivative thereof in the presence of a polycondensation catalyst. A liquid phase polycondensation step of producing a polyester (a) by liquid phase polycondensation, and (C) heating the polyester (a) to a temperature below the melting point in an inert gas atmosphere, and then in o-chlorophenol Intrinsic viscosity measured [η]
Solid phase polycondensation step for producing a polyester (b) having a ratio of 0.5 to 1.4 dl / g, and (D) drying the polyester (b) in an inert gas atmosphere having an oxygen concentration of 20 ppm or less. The polyester obtained by the manufacturing process including the drying process is molded by injection molding or extrusion molding to manufacture a molded product having a formaldehyde content of 1.0 ppm or less.

In the present invention, the polyester (a) obtained in the liquid-phase polycondensation step (A) is obtained by heating the polyester (a) at a temperature above the crystallization temperature (Tc ₁ ) prior to solid-phase polymerization. In addition, the pre-crystallization step (B) of keeping the temperature below the melting point for 1 to 30 minutes may be performed.

Each step will be described in detail below. (A) Liquid Phase Polycondensation Step In the present invention, first, in the liquid phase polycondensation step, a dicarboxylic acid containing terephthalic acid or an ester derivative thereof (eg, lower alkyl ester, phenyl ester, etc.)
And an esterified product of a dihydroxy compound containing ethylene glycol or an ester derivative thereof (for example, monocarboxylic acid ester ethylene oxide) are heated and melted in the presence of a polycondensation catalyst to carry out liquid phase polycondensation to obtain a polyester (a). To manufacture.

In the present invention, homopolyethylene terephthalate may be produced using terephthalic acid and ethylene glycol, and dicarboxylic acid containing terephthalic acid and dicarboxylic acid other than terephthalic acid and / or ethylene glycol and ethylene glycol other than ethylene glycol. It is also possible to produce a copolyester using a dihydroxy compound containing the dihydroxy compound.

Specific examples of the dicarboxylic acid other than terephthalic acid used for producing the copolyester include phthalic acid (orthophthalic acid), isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid and diphenoxyethanedicarboxylic acid. Aromatic dicarboxylic acid,
Examples thereof include aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and decanedicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and ester derivatives thereof. You may use these in combination of 2 or more types. Of these, isophthalic acid is preferably used.

Specific examples of the dihydroxy compound other than ethylene glycol include diethylene glycol, trimethylene glycol (propylene glycol), tetramethylene glycol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, diethylene glycol, triethylene glycol, Aliphatic glycols such as tetraethylene glycol and polyethylene glycol, alicyclic glycols such as cyclohexanedimethanol, bisphenols, hydroquinone, aromatic dihydroxy compounds such as 2,2-bis (4-β-hydroxyethoxyphenyl) propane and These ester derivatives etc. are mentioned. These are 2
You may use it in combination of 2 or more types. Of these, diethylene glycol and cyclohexanedimethanol are preferably used.

Dicarboxylic acids other than the terephthalic acid are
It is desirable that the dicarboxylic acid is used in an amount of 0 to 10 mol%, preferably 0 to 5 mol%, more preferably 0 to 3 mol%, and the dihydroxy compound other than ethylene glycol is 1 mol%.
It is desirable to use it in an amount of 0 to 10 mol%, preferably 0 to 5 mol%, and more preferably 0 to 3 mol% as 00 mol%.

Further, in the present invention, a small amount of a structural unit derived from a polyfunctional compound such as trimesic acid, pyromellitic acid, trimethylolethane, trimethylolpropane, trimethylolmethane and pentaerythritol is contained in a small amount, for example, 2 mol% or less. You may use.

In the liquid phase polycondensation step, the above-mentioned dicarboxylic acid or its ester derivative (hereinafter sometimes referred to simply as "dicarboxylic acid") and dihydroxy compound or its ester derivative (hereinafter simply referred to as "dihydroxy compound"). In this liquid phase polycondensation step, first, a dicarboxylic acid and a dihydroxy compound are usually subjected to an esterification reaction [esterification reaction step (A-1)], Then, a liquid phase polycondensation reaction [polycondensation reaction step (A-2)] is performed.

Specifically, first, a slurry containing a dicarboxylic acid and a dihydroxy compound is prepared. Such a slurry contains 1.02 to 1 mol of dicarboxylic acid.
It contains 2.0 mol, preferably 1.03 to 1.5 mol of dihydroxy compound.

This slurry has an esterification reaction step (A-
It is continuously supplied to 1). The esterification reaction is carried out by removing at least two esterification reactors in series using a device in which the dihydroxy compound is refluxed while removing water or alcohol produced by the reaction from the system in a rectification column. To be done.

The esterification reaction step (A-1) is usually carried out in multiple stages, and the esterification reaction in the first stage is usually at a reaction temperature of 240 to 270 ° C., preferably 245 to 265 ° C. and a pressure of 0.2 to. 3 kg / cm ² G, preferably 0.5-2 k
The esterification reaction at the final stage is usually carried out under the conditions of g / cm ² G and the reaction temperature is usually 250 to 280 ° C., preferably 255 to 275 ° C., and the pressure is 0 to 1.5 kg / cm.
It is carried out under the conditions of ² G, preferably 0 to 1.3 kg / cm ² G.

When the esterification reaction step (A-1) is carried out in three or more stages, from the second stage to the stage immediately before the final stage, the reaction conditions of the first stage and the final stage are used. Performed under conditions between the reaction conditions. For example, when the esterification reaction step is carried out in three stages, the esterification reaction in the second stage usually has a reaction temperature of 245 to 275 ° C., preferably 250 to 2 ° C.
70 ° C., pressure 0 to ² kg / cm ² G, preferably 0.2
It is carried out under the condition of ˜1.5 kg / cm ² G.

The reaction rate of the esterification reaction in each stage is not particularly limited, but it is preferable that the degree of increase in the esterification reaction rate in each stage is smoothly distributed, and the esterification reaction in the final stage is further performed. In the product, it is usually desired to reach 90% or more, preferably 93% or more.

An esterification product (low-order condensate) of a dicarboxylic acid and a dihydroxy compound is obtained by the esterification step (A-1), and the number-average molecular weight of the low-order condensate is usually 500 to 5000.

Such an esterification reaction can be carried out without adding an additive other than the dicarboxylic acid and the dihydroxy compound, or can be carried out in the coexistence of a polycondensation catalyst described later. In addition, tertiary amines such as trimethylamine, tri-n-butylamine and benzyldimethylamine, quaternary ammonium such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide and trimethylbenzylammonium hydroxide,
It can be carried out by adding a small amount of a basic compound such as lithium carbonate, sodium carbonate, potassium carbonate or sodium acetate. These basic compounds may be added to all of the esterification reactors, or may be added in the first stage or the second stage.
It may be added to a specific reactor after the first stage.

The esterified product thus obtained is
The liquid phase polycondensation reactor is continuously fed. In the liquid phase polycondensation reactor, the polycondensation catalyst is heated under reduced pressure in the presence of a polycondensation catalyst to a temperature equal to or higher than the melting point of the obtained polyester, and the glycol produced at this time is polycondensed while being distilled out of the system.

In the present invention, the polycondensation reaction step (A-2) comprises
It may be carried out in one step or in plural steps. When the polycondensation reaction step is carried out in a plurality of steps, the first-stage polycondensation reaction is usually a reaction temperature of 250 to 290 ° C., preferably 260 to 280 ° C., a pressure of 500 to 20 Torr,
It is preferably carried out under the conditions of 200 to 30 Torr, and the polycondensation reaction in the final stage is usually carried out at a reaction temperature of 265 to 300.
° C, preferably 270-295 ° C, pressure 10-0.1T
orr, preferably 5 to 0.1 Torr, particularly preferably 2 to 0.1 Torr.

When the polycondensation reaction step is carried out in three or more stages, the polycondensation reaction from the second stage to the one stage before the final stage is carried out under the reaction conditions of the first stage and the final stage. It is carried out under conditions in between. For example, the polycondensation reaction step is 3
If carried out in stages, the second stage polycondensation reaction is
Usually, the reaction temperature is 260 to 295 ° C., preferably 270 to
285 ° C., pressure 50 to 2 Torr, preferably 40 to
It is performed under the condition of 5 Torr.

In the present invention, in the above-mentioned (A) liquid phase polycondensation step, the intrinsic viscosity measured in o-chlorophenol at 25 ° C. is 0.8 to 1.5 dl / g, preferably 0. A polyester (a) of 0.8 to 1.2 dl / g is produced. Although the intrinsic viscosity reached in each stage except the final stage of the liquid phase polycondensation reaction step is not particularly limited, it is preferable that the degree of increase in the intrinsic viscosity in each stage is smoothly distributed.

In this specification, the intrinsic viscosity [η]
Is 1.2 g of polyester and 15 m of o-chlorophenol
Calculated from the solution viscosity measured at 25 ° C. after being dissolved by heating in 1 l, cooled.

The liquid phase polycondensation reaction as described above is carried out in the presence of a polycondensation catalyst. As the polycondensation catalyst, a germanium compound such as germanium dioxide, germanium tetraethoxide or germanium tetra n-butoxide, an antimony catalyst such as antimony trioxide or a titanium catalyst such as titanium tetrabutoxide can be used.

Of these polycondensation catalysts, a germanium dioxide compound is preferably used because a polyester excellent in hue and transparency can be obtained. The polycondensation catalyst as described above is 0.00 in terms of metal weight in the polycondensation catalyst based on the total weight of the dicarboxylic acid and the dihydroxy compound.
05-0.2% by weight, preferably 0.001-0.05
It is desirable to use it in a weight percentage.

The polycondensation reaction is preferably carried out in the presence of a stabilizer. Examples of stabilizers include phosphoric acid esters such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, and tricresyl phosphate, triphenyl phosphite, trisdodecyl phosphate, trisnonyl phenyl phosphate. Phosphite such as phytate, acidic phosphoric acid ester such as methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, dioctyl phosphate, and phosphorus compound such as phosphoric acid, polyphosphoric acid Used.

The stabilizer as described above is 0.001 to 0.1% by weight, preferably 0.002 to 0.002% by weight in terms of phosphorus atom weight in the stabilizer, based on the total weight of the dicarboxylic acid and the dihydroxy compound. It is preferably used in a proportion of 0.02% by weight.

These polycondensation catalysts and stabilizers can be supplied in the esterification step (A-1) as described above, or the first stage reactor of the polycondensation reaction step (A-2). Can also be supplied to.

The polyester (a) thus obtained from the final liquid-phase polycondensation reactor is usually formed into particles (chip shape) by the melt extrusion molding method. (B) Pre-crystallization step In the present invention, the polyester (a) thus obtained may be pre-crystallized.

In this pre-crystallization step, the polyester (a) in the dry state is heated to a temperature between the crystallization temperature (Tc ₁ ) and the melting point, preferably 10 ° C. higher than Tc ₁ and 40 ° C. higher than the melting point. Under, for 1 to 30 minutes, preferably 5
It is done by holding for ~ 20 minutes.

For example, when the polyester is polyethylene terephthalate, specifically, it is 160 to 200.
C., preferably 165 to 190.degree. C. for 1 to 30 minutes.

This pre-crystallization step is carried out in air or in an inert atmosphere, but it is preferably carried out in an inert atmosphere, more preferably in an inert atmosphere having an oxygen concentration of 20 ppm or less. .

The pre-crystallized polyester (a) is
It is desirable that the crystallinity is 20 to 50%. In the pre-crystallization step, the so-called solid phase polycondensation reaction of the polyester does not proceed, and the intrinsic viscosity of the pre-crystallized polyester (a) is the same as that of the polyester (a) obtained in the liquid phase polycondensation step (A). It is almost the same as the intrinsic viscosity, and the difference between the intrinsic viscosity of the pre-crystallized polyester (a) and the intrinsic viscosity of the pre-crystallized polyester (a) is usually 0.06d.
It is 1 / g or less.

By pre-crystallizing the polyester (a) in this way, the formaldehyde content in the polyester can be reduced. (C) Solid Phase Polycondensation Step In the present invention, the polyester (a) obtained as described above or the pre-crystallized polyester (a) is subjected to solid phase polycondensation.

The solid phase polycondensation step comprises at least one stage, and the polycondensation temperature is usually 190 to 230 ° C., preferably 1
95-225 ° C, pressure is usually 1 kg / cm ² G
-10 Torr, preferably normal pressure to 100 Torr
Under these conditions, the solid phase polycondensation reaction is carried out in an atmosphere of an inert gas such as nitrogen gas, argon gas or carbon dioxide gas. Of these inert gases, nitrogen gas is preferred. The oxygen concentration is preferably 20 ppm or less.

Polyester (b) thus obtained
The intrinsic viscosity of is usually 0.5 to 1.4 dl / g, preferably 0.7 to 1.3 dl / g. The density of this polyester (b) is usually 1.37 g.
/ Cm ³ or more, preferably 1.38 g / cm ³ or more, more preferably 1.39 g / cm ³ or more.

(D) Drying Step In the present invention, the polyester (b) obtained by solid phase polycondensation as described above is dried in an inert gas atmosphere.

In the drying step, the polyester (b) is
The heating is carried out at a temperature of 20 to 180 ° C., preferably 140 to 170 ° C. for 2 to 24 hours, preferably 2 to 12 hours, more preferably 2 to 6 hours under an inert gas atmosphere. At this time, the oxygen concentration in the inert gas is preferably 20 ppm or less, preferably 10 ppm or less, more preferably 5 ppm or less. The oxygen concentration is measured with an oxygen concentration meter.

Examples of the inert gas include nitrogen gas, argon gas and carbon dioxide gas, and nitrogen gas is particularly preferable. By heating under such conditions, the formaldehyde contained in the polyester is removed,
A polyester (c) having a very low formaldehyde content is obtained.

The following conditions are particularly preferable conditions in the drying step. (1) Inert gas: nitrogen gas, oxygen concentration: 5 ppm or less, temperature: 140 to 170 ° C., drying time 3 to 6 hours (2) Inert gas: nitrogen gas, oxygen concentration: 3 ppm or less, temperature: 150 to 170 C., drying time 3 to 5 hours Polycondensation reaction of the polyester hardly proceeds in this (D) drying step, and the intrinsic viscosity of the polyester (c) obtained through the drying step is obtained in the solid phase polycondensation step. It is almost the same as the intrinsic viscosity of the obtained polyester (b).

In the conventional manufacturing method, the step of drying the polyester subjected to the solid phase polymerization step with nitrogen gas or the like was performed, but in the conventional drying step, the oxygen concentration in the atmosphere was about 30 to 100 ppm. is there.

Molding of Polyester The polyester (c) obtained as described above is formed into various molded products by various molding methods.

For example, to mold a hollow molded article such as a bottle, first, polyester (c) is fed to a molding machine such as an injection molding machine to mold a preform for the hollow molded article. The formaldehyde content of the preform for hollow molding is 1.0 ppm or less. Next, this preform is inserted into a mold having a predetermined shape and stretch blow-molded to mold a hollow molded body. The formaldehyde content of this hollow molded article is 1.0 ppm or less.

The preform for a hollow molded article produced by the method of the present invention has a very low formaldehyde content in the polyester forming the preform for the hollow molded article, and therefore is used as a preform material for forming a container for filling beverages. It is preferably used. The hollow molded article produced by the method of the present invention has an extremely low formaldehyde content in the polyester forming the hollow molded article, and does not change the taste of the content, so that the beverage filling container (PET).
And a preform material for forming the bottle).

When a sheet or the like is molded, for example, an extruder is used to melt the melted polyester (c) into T
Mold by extruding from a die. The formaldehyde content of this sheet is 1.0 ppm or less.

The sheet produced by the method of the present invention comprises:
Since the formaldehyde content in the polyester forming the sheet is extremely low, it is suitable for use in food packaging and the like.

The polyester molded article of the present invention comprises a dicarboxylic acid containing terephthalic acid or its ester derivative,
Liquid-phase polycondensation of a dihydroxy compound containing ethylene glycol or its ester derivative in the presence of a polycondensation catalyst, followed by preliminary crystallization if necessary, and heating at a temperature below the melting point to carry out solid-phase polycondensation. A molded article made of polyester having an intrinsic viscosity [η] measured in o-chlorophenol in the range of 0.5 to 1.4 dl / g, which is obtained by further drying in an inert gas atmosphere. The formaldehyde content is 1.0 ppm or less.

The formaldehyde content of conventional polyester moldings is usually about 2 to 10 ppm, and no polyester molding having such a very low formaldehyde content exists. The polyester molded product of the present invention is suitably used particularly for applications such as food packaging.

[0059]

According to the method for producing a polyester molded product according to the present invention, a polyester molded product having an extremely low formaldehyde content can be obtained.

The polyester molded article of the present invention has an extremely low formaldehyde content and is therefore suitable for use in bottle-forming preforms, bottles, sheets and the like.

[0061]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples.

The formaldehyde content was measured and the transparency of the molded product was evaluated as follows. [Measurement of Formaldehyde Content] Approximately 2 g of a test piece was sampled from a polyester molded product and freeze-ground with a SPEX freeze-grinding machine. 1 g of the obtained polyester powder is put in a vial bottle, 2 ml of distilled water is added, and water and the polyester powder are mixed well. After closing the cap, the vial bottle is heated at 120 ° C. for 1 hour. After heating, cool in ice water,
The aqueous solution is transferred to another vial, 0.2 ml of 0.25% 2,4-dinitrophenylhydrazone 6N hydrochloric acid solution and 1 ml of hexane are added, and the container is sealed. After stirring and derivatization reaction, the hexane phase was measured by gas chromatography.

[Evaluation of Transparency] The transparency of the molded product was visually evaluated. The evaluation criteria are as follows.

◯: It was transparent without clouding. X: Cloudiness was observed.

[0065]

Example 1 Liquid phase polycondensation of the dicarboxylic acid and dihydroxy compound shown in Table 1, followed by pre-crystallization and solid phase polycondensation, and further at 150 ° C. for 4 hours in a nitrogen atmosphere (oxygen concentration; 5 ppm). And the intrinsic viscosity [η] is 0.86d.
1 / g of polyester was obtained.

A preform for forming a bottle (outer diameter of the mouth portion: 28 mmφ) was molded using the obtained polyester. As a molding machine, a famous machine M100A was used, and molding was performed under conditions of a set temperature of 275 ° C. and a mold temperature of 10 ° C. At this time, the hopper was in a nitrogen atmosphere.

The transparency of the obtained preform was evaluated, and a test piece was sampled from the mouth of the preform to measure the formaldehyde content. The results are shown in Table 1.

[0068]

Example 2 A dicarboxylic acid and a dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, followed by pre-crystallization, solid phase polycondensation, and further at 140 ° C. for 4 hours in a nitrogen atmosphere (oxygen concentration; 3 ppm). And the intrinsic viscosity [η] is 0.86d.
1 / g of polyester was obtained.

Using the obtained polyester, a preform for forming a bottle (outer diameter of the mouth portion: 28 m) was prepared in the same manner as in Example 1.
mφ) was molded. The transparency of the obtained preform was evaluated, and a test piece was sampled from the mouth of the preform to measure the formaldehyde content. The results are shown in Table 1.

[0070]

Example 3 A dicarboxylic acid and a dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, followed by pre-crystallization, solid phase polycondensation, and further at 150 ° C. for 4 hours in a nitrogen atmosphere (oxygen concentration: 1 ppm). And the intrinsic viscosity [η] is 0.84d.
1 / g of polyester was obtained.

Using the obtained polyester, a preform for forming a bottle (outer diameter of the mouth portion; 28 m) was prepared in the same manner as in Example 1.
mφ) was molded. Molded preform has 1 mouth
After immersing in silicon oil at 80 ° C. for 5 minutes for crystallization, a 1.5 liter bottle was molded. As the molding machine, Corpoplast LB01 was used, and molding was performed under the conditions of heat setting at a stretching temperature of 105 ° C. and a mold temperature of 130 ° C.

The transparency of the obtained bottle was evaluated, and a test piece was sampled from the body of the bottle to measure the formaldehyde content. The results are shown in Table 1.

[0073]

Example 4 The dicarboxylic acid and dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, followed by pre-crystallization, solid phase polycondensation, and further at 150 ° C. for 4 hours in a nitrogen atmosphere (oxygen concentration; 4 ppm). And the intrinsic viscosity [η] is 0.75d.
1 / g of polyester was obtained.

A sheet (thickness: 0.6 mm) was molded using the obtained polyester. Molding machine is Hitachi 50mm
Using φ, molding was performed under the condition of a preset temperature of 275 ° C. At this time, the hopper was in a nitrogen atmosphere.

The transparency of the obtained sheet was evaluated, and a test piece was sampled from the sheet to measure the formaldehyde content. The results are shown in Table 1.

[0076]

Example 5 The dicarboxylic acid and dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, followed by pre-crystallization, solid phase polycondensation, and further at 140 ° C. for 4 hours in a nitrogen atmosphere (oxygen concentration; 5 ppm). And the intrinsic viscosity [η] is 0.86d.
1 / g of polyester was obtained.

Using the polyester obtained, in the same manner as in Example 1, a preform for forming a bottle (outer diameter of mouth portion: 28 m)
mφ) was molded. The transparency of the obtained preform was evaluated, and a test piece was sampled from the mouth of the preform to measure the formaldehyde content. The results are shown in Table 1.

[0078]

Example 6 The dicarboxylic acid and the dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, followed by pre-crystallization, solid phase polycondensation, and further at 150 ° C. for 4 hours in a nitrogen atmosphere (oxygen concentration; 5 ppm). And the intrinsic viscosity [η] is 1.10d.
1 / g of polyester was obtained.

Using the polyester thus obtained, a preform for forming a bottle (outer diameter of the mouth portion; 28 m) was prepared in the same manner as in Example 1.
mφ) was molded. The transparency of the obtained preform was evaluated, and a test piece was sampled from the mouth of the preform to measure the formaldehyde content. The results are shown in Table 1.

[0080]

Example 7 The dicarboxylic acid and dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, followed by pre-crystallization, solid phase polycondensation, and further at 140 ° C. for 4 hours in a nitrogen atmosphere (oxygen concentration; 5 ppm). And the intrinsic viscosity [η] is 0.75d.
1 / g of polyester was obtained.

A sheet (thickness: 0.6 mm) was molded using the obtained polyester in the same manner as in Example 4. The transparency of the obtained sheet was evaluated, and a test piece was sampled from the sheet to measure the formaldehyde content. The results are shown in Table 1.

[0082]

Comparative Example 1 The dicarboxylic acid and dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, pre-crystallization, solid phase polycondensation, and further dried at 150 ° C. for 4 hours in an air atmosphere to obtain an intrinsic viscosity. Polyester having a [η] of 0.86 dl / g was obtained.

Using the polyester obtained, in the same manner as in Example 1, a bottle forming preform (mouth outer diameter: 28)
mmφ) was molded. At this time, the hopper was placed in a dry air atmosphere.

The transparency of the obtained preform was evaluated, and a test piece was sampled from the mouth of the preform to measure the formaldehyde content. The results are shown in Table 1.

[0085]

Comparative Example 2 The dicarboxylic acid and dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, then pre-crystallization, solid phase polycondensation, and further dried at 150 ° C. for 4 hours in an air atmosphere to obtain an intrinsic viscosity. A polyester having an [η] of 0.75 dl / g was obtained.

A sheet (thickness: 0.6 mm) was molded using the obtained polyester in the same manner as in Example 4. At this time, the hopper was placed in a dry air atmosphere. The transparency of the obtained sheet was evaluated, and a test piece was sampled from the sheet to measure the formaldehyde content. The results are shown in Table 1.

[0087]

Comparative Example 3 The dicarboxylic acid and the dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, followed by preliminary crystallization, solid phase polycondensation, and further drying at 150 ° C. for 4 hours in an air atmosphere to obtain an intrinsic viscosity. A polyester having an [η] of 0.45 dl / g was obtained.

Using the polyester thus obtained, a preform for forming a bottle (outer diameter of the mouth portion; 28) was prepared in the same manner as in Example 1.
mmφ) was molded. At this time, the hopper was placed in a dry air atmosphere.

While evaluating the transparency of the obtained preform, a test piece was sampled from the mouth of the preform (mouth outer diameter: 28 mmφ), and the formaldehyde content was measured. The results are shown in Table 1.

[0090]

[Comparative Example 4] The dicarboxylic acid and dihydroxy compound shown in Table 1 were subjected to liquid phase polycondensation, followed by pre-crystallization, solid phase polycondensation, and further at 150 ° C for 4 hours in a nitrogen atmosphere (oxygen concentration; 50 ppm). And the intrinsic viscosity [η] is 0.75
dl / g polyester was obtained.

Using the polyester obtained, a preform (outer diameter of the mouth portion: 28 mmφ) was molded in the same manner as in Example 1. The transparency of the obtained preform was evaluated, and a test piece was sampled from the mouth of the preform to measure the formaldehyde content. The results are shown in Table 1.

[0092]

[Table 1]

Claims (5)

(57) [Claims] 1. A polyester (a) obtained by liquid-phase polycondensing (A) a dicarboxylic acid containing terephthalic acid or an ester derivative thereof and a dihydroxy compound containing ethylene glycol or an ester derivative thereof in the presence of a polycondensation catalyst. And (C) heating the polyester (a) to a temperature equal to or lower than the melting point in an inert gas atmosphere so that the intrinsic viscosity [η] measured in o-chlorophenol is 0. Solid phase polycondensation step of producing polyester (b) in the range of 0.5 to 1.4 dl / g, and (D) the polyester (b) having an oxygen concentration of 20 ppm.
A polyester obtained by a manufacturing process including a drying process of drying in the following inert gas atmosphere is molded by injection molding or extrusion molding to manufacture a molded product having a formaldehyde content of 1.0 ppm or less. A method for producing a characteristic polyester molded product. 2. A polyester (a) obtained by liquid-phase polycondensing (A) a dicarboxylic acid containing terephthalic acid or an ester derivative thereof and a dihydroxy compound containing ethylene glycol or an ester derivative thereof in the presence of a polycondensation catalyst. A liquid phase polycondensation step of producing (B) the polyester (a) is heated to a crystallization temperature (T
c ₁ ) a pre-crystallization step of keeping at a temperature not lower than the melting point and lower than the melting point for 1 to 30 minutes, and (C) a polyester (a) which has undergone the pre-crystallization step
Is heated to a temperature equal to or lower than the melting point in an inert atmosphere, and the intrinsic viscosity [η] measured in o-chlorophenol is 0.5 to
Solid phase polycondensation step for producing polyester (b) in the range of 1.4 dl / g, and (D) the polyester (b) having an oxygen concentration of 20 ppm
A polyester obtained by a manufacturing process including a drying process of drying in the following inert gas atmosphere is molded by injection molding or extrusion molding to manufacture a molded product having a formaldehyde content of 1.0 ppm or less. A method for producing a characteristic polyester molded product. 3. The content of isophthalic acid in the dicarboxylic acid is in the range of 0 to 10 mol%, the content of diethylene glycol in the dihydroxy compound is 0 to 10 mol%, and the content of cyclohexanedimethanol is 0. The method for producing a polyester molded product according to claim 1 or 2, which is in the range of 10 to 10 mol%. 4. The method for producing a polyester molded article according to claim 1, wherein the drying temperature in the drying step (D) is in the range of 120 to 180 ° C. 5. The method for producing a polyester molded article according to claim 1, wherein the drying time in the drying step (D) is in the range of 2 to 24 hours.