JPH04139221A - Polyethylene terephthalate molded article - Google Patents

Abstract

PURPOSE:To obtain the title molded article not larger than a specific range in oligomer amount increased when heated under specific conditions, having a specific intrinsic viscosity, hardly causing stain of mold, having good appearance and useful as a vessel raw material for packing drink such as juice. CONSTITUTION:The objective molded article consisting of a polyethylene terephthalate molded article having >=0.50dl/g intrinsic viscosity and <=0.55wt.% oligomer (cyclic trimer) content, in which increase amount y (wt.%) of oligomer after heating and melting the molded article under nitrogen stream at 290 deg.C for 7min is expressed by the equation y<=-0.72x+0.40 ((x) is oligomer concentration of molded article).

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to polyethylene terephthalate molded bodies such as bottles, preforms, and sheets, and more particularly to polyethylene terephthalate molded bodies with a small increase in oligomer.

Technical background of the invention and its problems Various resins have been used as materials for containers for seasonings, oils, beverages, cosmetics, detergents, etc., depending on the type of contents and the purpose of use. .

Among these, polyethylene terephthalate has excellent mechanical strength, heat resistance, transparency, and gas barrier properties, and is therefore particularly suitable as a material for containers for filling beverages such as juices, soft drinks, and carbonated drinks.

Such polyethylene terephthalate bottles are supplied to a molding machine such as an injection molding machine to form a preform for a hollow molded object, and this preform is heated and inserted into a mold of a predetermined shape for stretch blow molding. It is common to further perform a post-heat treatment (heat setting) to form a blow-molded container.

However, conventionally known polyethylene terephthalate molded products contain oligomers such as cyclic trimers, and these oligomers such as cyclic trimers are exposed to the inner surface of the mold, the gas exhaust port of the mold, the exhaust pipe, etc. Mold contamination was likely to occur due to adhesion to the mold.

Such mold stains cause surface roughening and whitening of the resulting molded product, such as a bottle. If a molded object such as a bottle becomes white, the molded object must be discarded. For this reason, when molding a molded article using conventionally known polyethylene terephthalate, mold stains must be removed frequently, resulting in a major problem in that bottle productivity is significantly reduced.

In view of the above-mentioned current situation, the inventors of the present invention conducted intensive research to obtain a polyethylene terephthalate molded product such as a bottle that does not cause mold stains during molding, and found that it has a specific intrinsic viscosity and an oligomer. A polyethylene terephthalate molded product with a (cyclic trimer) content below a specific value and an increase in oligomers within a specific range when the molded product is heated under specific conditions must be molded into a mold during the manufacturing process. The present invention was completed based on the discovery that there is little dirt, the appearance is good, and there is little dirt or clogging in the mold line.

Purpose of the Invention The present invention is intended to solve the problems associated with the prior art as described above. The purpose of the present invention is to provide a polyethylene terephthalate molded product that is difficult to cause corrosion and has a good appearance.

Summary of the Invention The polyethylene terephthalate molded article according to the present invention has an intrinsic viscosity of 0. 50 dj! ' A polyethylene terephthalate molded product having a weight of 7 g or more and an oligomer content of 0.55% by weight or less, and the oligomer obtained by heating and melting the polyethylene terephthalate molded product at a temperature of 290° C. for 7 minutes under nitrogen flow. The increase amount y (weight %) is y≦−0,74x+0.40 [where y is the oligomer increase amount (weight %) after heating, and X is the oligomer concentration (weight %) of the molded body. ].

In the polyethylene terephthalate molded product according to the present invention, since the amount of oligomers that increases when the polyethylene terephthalate molded product is heated is specified as described above, the total amount of oligomers such as cyclic trimers contained in the polyethylene terephthalate at the time of molding. Therefore, the appearance of the molded product is good, and mold stains and whitening of the molded product are less likely to occur.

DETAILED DESCRIPTION OF THE INVENTION The polyethylene terephthalate molded article according to the present invention will be specifically described below.

The polyethylene terephthalate molded article according to the present invention has a specific intrinsic viscosity and an oligomer content of 0.
．． It is 55% by weight or less, preferably 0.45% by weight or less, and the amount of increase in the oligomer when melted and heated under specific conditions is not more than a specific value.

Polyethylene terephthalate, which is the raw material for the polyethylene terephthalate molded article described above, is produced using terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative as raw materials, and this polyethylene terephthalate contains 20 mol%.
The following other dicarboxylic acids and/or other glycols may be copolymerized.

Examples of dicarboxylic acids used in copolymerization other than terephthalic acid include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, and diphenoxyethane dicarboxylic acid, adipic acid, sebacic acid, Examples include aliphatic dicarboxylic acids such as azelaic acid and decanedicarboxylic acid, and ring dicarboxylic acids such as cyclohexanedicarboxylic acid.

Glycols other than ethylene glycol used for copolymerization include aliphatic glycols such as trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, cyclohexane dimetatool, etc. Examples include aromatic diols such as ring glycols, bisphenols, hydroquinone, and 2,2-bis(4-β-hydroxyethoxyphenyl)propane.

The raw materials containing terephthalic acid or its ester-forming derivative as described above and ethylene glycol or its ester-forming derivative are esterified in the presence of an esterification catalyst and then converted into a liquid phase in the presence of a polycondensation catalyst. Polycondensation is performed, followed by solid phase polycondensation.

As a method for producing polyethylene terephthalate, which is a raw material for the polyethylene terephthalate molded article according to the present invention, either a batch method or a continuous method may be adopted, but one example of a preferable continuous manufacturing method will be specifically explained below. However, the present invention is not limited to these manufacturing methods. Specifically, first, a slurry containing terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative is prepared.

Such a slurry contains 1.02 to 1.4 moles, preferably 1.03 to 1.3 moles of ethylene glycol or its ester-forming derivative per mole of terephthalic acid or its ester-forming derivative. . This slurry is continuously fed to the esterification reaction step.

The esterification reaction is carried out using an apparatus in which at least two esterification reactors are connected in series, under conditions where ethylene glycol is refluxed, and water produced by the reaction is removed from the system in a rectification column. . The reaction conditions for carrying out the esterification reaction are that the temperature of the first stage esterification reaction is usually 240 to 270°C, preferably 245 to 265°C, and the pressure is usually 0.2 to 3 kg/CiG, preferably 0. 5
~2kg/alf, and the temperature of the final stage esterification reaction is usually 250~280℃, preferably 255~280℃.
The temperature is 75°C, and the pressure is usually 0 to 1. 5 kg/alG, preferably 0 to 1.3 kg/ciG.

Therefore, when the esterification reaction is carried out in two stages, the esterification reaction conditions in the first stage and the second stage are within the above-mentioned ranges, and when the esterification reaction is carried out in three or more stages, the esterification reaction conditions in the second stage are The reaction conditions of the esterification reaction from the second stage to one stage before the final stage are between the reaction conditions of the first stage and the final stage.

For example, when the esterification reaction is carried out in three stages, the reaction temperature of the second stage esterification reaction is usually 245
-275°C, preferably 250-270°C, and the pressure is usually 0-2kg/ciG, preferably 0.2-1.5kg
/ciG. The reaction rate of these esterification reactions is
Although there is no particular restriction on each stage, it is preferable that the increase and degree of esterification reaction rate in each stage is smoothly distributed, and furthermore, the esterification reaction product in the final stage is usually 90% or more. , preferably 9
It is desirable to reach 3% or more.

A lower condensate is obtained through these esterification steps, and the number average molecular weight of this lower condensate is usually 500 to 500.
It is 0.

Such an esterification reaction can be carried out without adding any additives other than terephthalic acid and ethylene glycol, or in the coexistence of a polycondensation catalyst described below, but it is also possible to carry out it in the presence of a polycondensation catalyst described below. , tri-n-butylamine, benzyldimethylamine, etc.
A small amount of quaternary ammonium hydroxide such as tetraethylammonium hydroxide, tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, trimethylbenzylammonium hydroxide, and basic compounds such as lithium carbonate, sodium carbonate, potassium carbonate, and sodium acetate. This is preferred because the proportion of dioxyethylene terephthalate component units in the main chain of polyethylene terephthalate can be maintained at a relatively low level.

The obtained lower-order condensate is then heated under reduced pressure in the presence of a polycondensation catalyst to a temperature higher than the melting point of the obtained polyethylene terephthalate, and the glycol produced at this time is distilled out of the system to perform polycondensation. Supplied to the liquid phase polycondensation process.

Such a polycondensation reaction in a liquid phase may be carried out in one step or may be carried out in multiple steps. When carrying out the polycondensation reaction in multiple stages, the polycondensation reaction conditions are such that the reaction temperature for the first stage polycondensation is usually 250 to 290°C, preferably 260 to 280°C.
0°C, the pressure is usually 500 to 20 To++, preferably 200 to 30 Tor+, and the temperature of the final stage polycondensation reaction is usually 265 to 300°C, preferably 270
~295°C, and the pressure is usually 10-0.1 To++, preferably 5-0. 5To++.

When the polycondensation reaction is carried out in two stages, the polycondensation reaction conditions for the first stage and the second stage are within the above ranges, and when the polycondensation reaction is carried out in three or more stages, from the second stage The reaction conditions for the polycondensation reaction up to one stage before the final stage are between the reaction conditions for the first stage and the reaction conditions for the final stage.

For example, if the polycondensation reaction is carried out in three stages,
The reaction temperature of the second stage polycondensation reaction is usually 260 to 295
℃ Preferably 270 to 285℃, and the pressure is usually 5
It is in the range of 0 to 2 To++, preferably 40 to 5 TOII. Although there is no particular restriction on the intrinsic viscosity (IV) reached in each of these polycondensation reaction steps, it is preferable that the degree of increase in the intrinsic viscosity in each stage is smoothly distributed, and furthermore, in the final stage of polycondensation The intrinsic viscosity (IV) of polyethylene terephthalate obtained from the reactor is usually 0.
．． 50-1. ．． 0OdI/g preferably 0.65-0.
A range of 8 OdI/g is desirable.

In this specification, the intrinsic viscosity is calculated from the solution viscosity measured at 25° C. after heating and dissolving 1.2 g of polyethylene terephthalate in 0 to 15 cc of chlorophenol, followed by cooling.

The polycondensation reaction as described above is preferably carried out in the presence of a catalyst and a stabilizer. As the catalyst, germanium compounds such as germanium dioxide, germanium tetraethoxide, germanium tetra-n-butoxide, antimony catalysts such as antimony trioxide, and titanium catalysts such as titanium tetrabutoxide can be used. Among these catalysts, germanium dioxide compounds are preferred because the produced polyethylene terephthalate has excellent hue and transparency. In addition, as stabilizers, phosphoric acid esters such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, triphenyl phosphite, trisdodecyl phosphite, trisnonylphenyl Phosphite esters such as phosphite, acidic phosphate esters such as methyl arashido phosphate, isoprobil arashido phosphate, butyl arashido phosphate, dibutyl phosphate, monobutyl phosphate, dioctyl phosphate, phosphoric acid, polyphosphoric acid, etc. Phosphorus compounds are used. The proportion of these catalysts or stabilizers to be used is usually preferably 0.0005 to 0.2% by weight based on the weight of the metal in the catalyst, based on the weight of the mixture of terephthalic acid and ethylene glycol. is in the range of 0.001 to 0.05% by weight, and in the case of a stabilizer, it is usually 0.001 to 0.1% by weight, preferably 0.002 to 0.1% by weight, based on the weight of phosphorus atoms in the stabilizer.
The range is 0.02% by weight. These catalysts and stabilizers can be supplied at the stage of the esterification reaction process, or can be supplied to the first stage reactor of the polycondensation reaction process.

The polyethylene terephthalate used as a raw material in the present invention may contain dicarboxylic acids other than terephthalic acid and diols other than ethylene glycol in an amount of 20 mol% or less as described above, but polyethylene terephthalate is particularly preferably used. is a dioxyethylene terephthalate component unit (a content of dioxyethylene terephthalate component unit (a) represented by the general formula [I] in the range of 95.0 to 99.0 mol%) The content is preferably in the range of .0 to 5.0 mol%.

The raw material polyethylene terephthalate thus obtained from the final polycondensation reactor is usually molded into granules (chips) by melt extrusion.

The granular polyethylene terephthalate as such a raw material usually has a diameter of 2.0 to 5.5 mm, preferably 2.2 to 4 mm.
．． It is desirable to have an average particle size of 0.

The granular polyethylene terephthalate obtained as described above is fed to a solid phase polycondensation step.

The granular polyethylene terephthalate to be supplied to the solid phase polymerization step may be pre-crystallized by heating to a temperature lower than the temperature at which solid phase polycondensation is performed, and then supplied to the solid phase polycondensation step.

Such a pre-crystallization step can be carried out by heating the granular polyethylene terephthalate in a dry state, usually at a temperature of 120 to 200°C, preferably 130 to 180°C, for 1 minute to 4 hours, or by heating the granular polyethylene terephthalate with water vapor. Alternatively, it can also be carried out by heating at a temperature of usually 120 to 200° C. for 1 minute or more in an inert gas atmosphere containing water vapor.

The solid phase polycondensation step in which granular polyethylene terephthalate is supplied as described above consists of at least one stage, and the polycondensation temperature is usually 190 to 230°C, preferably 195 to 225°C.
℃, and the pressure is usually 1 kg/ciG ~ 10 T
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, preferably under conditions of normal pressure to 100 To++. Among these inert gases, nitrogen gas is preferred.

In such raw material polyethylene terephthalate, 0.
It is desirable that the amount is 55% by weight or less, preferably 0.145% by weight or less.

In this specification, the amount of oligomer contained in polyethylene terephthalate is measured as follows.

That is, after dissolving a predetermined amount of polyethylene terephthalate in 0-chlorophenol, it is reprecipitated with tetrahydrofuran and filtered to remove linear polyethylene terephthalate, and then the obtained filtrate is subjected to liquid chromatography (
The amount of oligomers contained in polyethylene terephthalate is determined by supplying the polyethylene terephthalate to a polyethylene terephthalate (LC7A) manufactured by Takafusa Manufacturing Co., Ltd., and dividing this value by the amount of polyethylene terephthalate used in the measurement, the amount of oligomers contained in polyethylene terephthalate (
weight%).

The raw material polyethylene terephthalate used as a raw material in the present invention can be obtained by subjecting the above-mentioned granular polyethylene terephthalate to water, water vapor, or steam-containing water. This is done by bringing it into contact with a gas or the like.

The contact between the granular polyethylene terephthalate as a raw material and water is carried out by immersing the polyethylene terephthalate in water at a temperature of 1 to 150°C for 1 minute to 100 hours, or more preferably 5 minutes to 10 hours. Desirably, granular polyethylene terephthalate is immersed in water at 30 to 150°C for 1 minute to 10 hours.

More desirably, granular polyethylene terephthalate is immersed in water at 40 to 110°C for 3 minutes to 5 hours. Particularly preferably, granular polyethylene terephthalate is immersed in hot water at 50 to 100°C for 5 minutes to 3 hours.

Further, the contact between granular polyethylene terephthalate as a raw material and water vapor or water vapor-containing gas is usually 1 to 150%.
°C, preferably 40 to 150 °C, more preferably 50 °C
Water vapor or water vapor-containing gas or water vapor-containing air at a temperature of ~110°C is mixed with granular polyethylene terephthalate 1
This is carried out by supplying the water vapor in an amount of 0.5 g or more per kg, or by bringing the granular polyethylene terephthalate into contact with the water vapor in the presence of the water vapor. The contact between the granular polyethylene terephthalate and water vapor is usually carried out for 1 minute to 1 year, preferably for 5 minutes to 14 days, more preferably for 10 minutes to 2 days, and particularly preferably for 20 minutes to 10 hours.

Examples of industrial methods of contact treatment with water, steam, or steam-containing gas are shown below, but the present invention is not limited thereto. Furthermore, the treatment method may be either continuous or batch.

When granular polyethylene terephthalate as a raw material is subjected to contact treatment with water in a batch manner, a silo type treatment apparatus is used. That is, granular polyethylene terephthalate is received in a silo, and water, steam, or a steam-containing gas is supplied in a batch method to perform contact treatment. Alternatively, the granular polyethylene terephthalate may be received in a rotating cylinder type contact treatment device and the contact treatment may be performed while rotating to make the contact more efficient.

When granular polyethylene terephthalate is continuously treated in contact with water, the granular polyethylene terephthalate is continuously received from the upper part of the base treatment device, and water, water vapor, or water vapor-containing gas is continuously supplied in cocurrent or countercurrent. Can be treated in contact with water.

Thereafter, when treated with water, the granular polyethylene terephthalate is drained using a water drainer such as a vibrating sieve or a Simon Carter, and then transferred to the next drying process. When treated with water vapor or water vapor-containing gas, it can be directly transferred to the drying process.

For drying the granular polyethylene terephthalate that has been subjected to the contact treatment with water, a commonly used polyethylene terephthalate drying apparatus can be used.

As a method for continuous drying, a hopper-type ventilation dryer is usually used, which supplies granular polyethylene terephthalate from the upper part and aerates drying gas from the lower part. As a method of reducing the amount of drying gas and drying efficiently, a continuous dryer with a rotating disk type heating method is selected.While a small amount of drying gas is vented, heated steam, heat medium, etc. are supplied to the rotating disk or external jacket. The granular polyethylene terephthalate can be indirectly heated and dried.

A double cone rotary dryer is selected as a dryer for batch drying, and can perform drying under vacuum or above vacuum while passing a small amount of drying gas. Alternatively, drying may be performed under atmospheric pressure while blowing dry gas.

As the dry gas, atmospheric air may be used, but dry nitrogen or dehumidified air is preferable from the viewpoint of preventing molecular weight reduction due to hydrolysis of polyethylene terephthalate.

In this way, by bringing the raw material polyethylene terephthalate into contact with water or water vapor, and subjecting the polyethylene terephthalate to water treatment, a polyethylene terephthalate molded article manufactured from the obtained polyethylene terephthalate is heated by heating calculated as described below. The subsequent increase in oligomers is reduced.

By water-treating raw material polyethylene terephthalate in this way, the increase in oligomers such as cyclic trimers during molding of polyethylene terephthalate is reduced. This is caused by the catalytic action of the polycondensation catalyst, and the force A
This is probably because this polycondensation catalyst is deactivated by the water treatment of polyethylene terephthalate.

The polyethylene terephthalate molded body formed from the raw material polyethylene terephthalate obtained as described above has an oligomer content of 0 as measured as described above.
．． It is 55% by weight or less, preferably 0.45% by weight or less.

In addition, the polyethylene terephthalate molded product of the present invention 1 obtained in this way + 1, under nitrogen flow, temperature 29
Increase amount y of the first nogomer after heating and melting at 0°C for 7 minutes (
Weight %) is preferably y≦-0,72x+0.40 (y≦-〇, 72x+0.38 and more preferably C'!y≦-
〇, 72x+0.36.

In the above formula, X is the oligomer concentration (% by weight) of the molded article.

In this specification, the amount of oligomer increase (% by weight) after melting and heating a polyethylene terephthalate molded body is measured as follows.

Below, when explaining the polyethylene terephthalate molded product using a bottle as an example, 2 to 5 w from the mouth of the bottle.
Cut out a corner (Q, 20~G, 35g) sample, 140
Dry in nitrogen at 360 tor+ for 16 hours at 0.degree.

Next, using a moisture vaporizer EV-6 manufactured by Heiton Sangyo Co., Ltd., the temperature was heated to 220°C in advance while flowing dry nitrogen at a rate of 0.251/min.
A diameter of 25 m was heated for 10 minutes at room temperature and then cooled for 5 minutes at room temperature.
The sample is attached to a Pyrex sampling board and charged into a Pyrex tube. Next, the sample was heated at 220°C for 15 minutes while flowing dry nitrogen, cooled for 10 minutes at room temperature, immersed in silicone oil set at 290°C for 7 minutes, melted and heated, and heated at room temperature for 5 minutes.
Cool for a minute and remove the sample.

The oligomer concentration of the sample thus treated is determined as described above.

Effects of the Invention The polyethylene terephthalate molded article according to the present invention has an intrinsic viscosity of 0. 50 dJ /g or more and an oligomer content of 0.55% by weight or less, and the oligomer increase after heating and melting the polyethylene terephthalate molded article at a temperature of 290°C for 7 minutes in a nitrogen atmosphere. The amount y (weight%) is y
≦-〇, 74x+0.40 (in the formula, X is the oligomer concentration after heating), so the total amount of oligomers contained in the polyethylene terephthalate molded product during molding is small, so the precipitation of oligomers is small and the appearance is excellent.

Therefore, the polyethylene terephthalate molded product according to the present invention does not require frequent cleaning of the mold etc. during its production, so it is possible to improve the productivity of molded products such as bottles, films, sheets, etc. Molded objects such as bottles, films, and sheets are prevented from whitening and have a good appearance.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Intrinsic viscosity is 0.80 617g, density is 1.40
5 kg of granular polyethylene terephthalate with an oligomer content of 0.28% by weight were immersed in 6.5 kg of distilled water in a stainless steel container.

Next, the stainless steel container containing polyethylene terephthalate and distilled water was heated from the outside, the internal temperature was controlled at 90°C, and the temperature was maintained for 4 hours to perform hot water treatment.
Polyethylene terephthalate chips were obtained by dehydration and drying.

Next, these polyethylene terephthalate chip 2 rice grains were dried overnight at 150°C under reduced pressure, and then dried in an 8-layer Ni-Nis-Bee Machine ASllI5G) I with a basis weight of 45 g and a thickness of 4.5 m.
A molded body (preform) was molded.

Molding is performed under a nitrogen atmosphere by flowing dry nitrogen under the injection hopper at 100 A'/min.Cylinder temperature settings are cylinder 1/cylinder 2/cylinder 3/nozzle = 260/270/270/300°C from the hopper side, screw rotation. 100 r, p, m, the entire cycle was 30 seconds.

2 to 5IIIl from the spout of the obtained preform
Corner +7) Approximately 0.20 to 0.35 g of the sample was sampled and the oligomer was measured, and the sample was dried by the method described above, and then melted at 290° C. for 7 minutes, and then the oligomer was measured. Oligolimer in preform is 0.29
% by weight, and the oligomer after melt processing was 0.39% by weight. Therefore, the increase was 0.10% by weight.

Example 2 Intrinsic viscosity is 0.80 dl/g and density is 1.40 g
Polyethylene terephthalate having an oligomer content of 0.33% by weight was treated with hot water in the same manner as in Example 1, and then dried and molded using ASB150H in the same manner to obtain a preform. In addition to measuring the oligomer in the preform, a sample was sampled from the preform plug in the same manner as in Example 1, dried and melted, and the oligomer was measured.

The oligomer content in the preform was 0.34% by weight, and the oligomer content after melt processing was 0.42% by weight. Therefore, the increase was 0.08% by weight.

Example 3 Intrinsic viscosity is 0.80d7/g and density is 1.40g
/- and having an oligomer content of 0.40% by weight was treated with hot water in the same manner as in Example 1, and then similarly molded into an 8-volume ASB preform.

The oligomer content of the obtained preform was measured in the same manner as in Example 1, and the oligomer content after drying and melting at 290°C for 7 minutes was also measured.

The oligomer in the preform was 0.41% by weight. The oligomer content after melt processing was 0.47% by weight.

Therefore, the increase was 0.06% by weight.

Example 4 The intrinsic viscosity used in Example 3 was 0. 80 cl’ 7g.

Polyethylene terephthalate having an oligomer content of 0.33% by weight was treated with hot water in the same manner as in Example 3, and then dried at 150°C under reduced pressure for about 16 hours. - Using a 3J type injection molding machine, melt the barrel at a set temperature of 280℃ and injection mold it into a preform mold cooled to 10℃ at a molding pressure cuff of 00kg/cnf. A preform weighing 64 g and having a body part thickness of 4.5 strokes was produced at a molding cycle of 60 seconds.The oligomer content in the obtained preform was 0.35% by weight.

Next, a preform was prepared in which only the spout part was crystallized in an oil bath at 160°C. This spout crystallized preform was molded using a biaxial stretching blow molding machine [Copoplast (C0RPOP)].
Blow pressure 2 using LBOIO manufactured by LAST)
0 kg/al, preform heating time approximately 60 seconds, stretching temperature 105°C, biaxially stretched approximately 2.2 times in length and approximately 3.0 times in width, and further inside a mold with a surface temperature of 160°C. After holding the mold for 60 seconds, heat setting was performed by cooling the mold with water for 20 seconds, and the mold was made into a biaxial mold with an internal volume of 1.51 cm, a body with a vacuum panel of 6 times the size, and a raised bottom. A stretched bottle was produced.

In addition, heating (heat setting) for 60 seconds after stretching was
This test is intended to accelerate bottle whitening for evaluation, and a heating (heat setting) time of 0.1 to 30 seconds during bottle manufacturing is sufficient.

500 bottles were molded, all of which were transparent.

A sample was taken from the mouth of the bottle, dried in the same manner as in Example 1, and then melted at 290° C. for 7 minutes.

The oligomer content after treatment was 0.42% by weight.

Therefore, the increase was 0.07% by weight.

Comparative Example 1 A preform was molded and melt-treated in the same manner as in Example 1, except that the polyethylene terephthalate used in Example 1 was not subjected to hot water treatment. The oligomer in the preform was 0.36% by weight and the oligomer after melt processing was 0.59% by weight. Therefore, the increase is 0.23
% by weight.

Comparative Example 2 Intrinsic viscosity is 0. 80 dJ 7g, and the density is 1.
40g/- and oligomer content is 0.47% by weight
A preform was molded from polyethylene terephthalate in the same manner as in Comparative Example 1, and then melted. The oligomer in the preform was 0.52% by weight and the oligomer after melt processing was 0.64% by weight. Therefore, the increase was 0.12% by weight.

Comparative Example 3 The polyethylene terephthalate used in Example 1 was dried and molded in the same manner as in Comparative Example 1 without hot water treatment and in the same manner as in Example 1. 50 bottles as in Example 4
Although 0 bottles were molded, bottles with a cloudy pattern started to appear after the 400th bottle. Note that the oligomer content in the obtained preform was 0.46% by weight.

A sample was taken from the mouth of the bottle, dried in the same manner as in Example 1, and then melted at 290° C. for 7 minutes. The oligomer content after treatment was 0.60% by weight. Therefore, the increase was 0.14% by weight.

Example 5 Intrinsic viscosity is 0. 80 dj! 7g, and the density is 1
．． 40g/- and the oligomer content is 0.28% by weight, the same polyethylene terephthalate as in Example 1 was treated with ASB150 without hot water treatment.
A preform was molded in the same manner at H, a sample was similarly sampled from the preform bottom stopper, the amount of oligomer was measured, and the sample was heated at 95°C for 8 hours with the sample and distilled water 12 in a sample bottle. Treated with hot water.

After this treatment, the sample was dried in the same manner as in Example 1, and then
Oligomers were measured after melt processing at 0° C. for 7 minutes. The oligomer content in the preform was 0.33% by weight, and the oligomer content after melt processing was 0.36% by weight. Therefore, the increase was 0.03% by weight.

The above results are shown in FIG.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the amount of oligomer contained in the molded body and the amount of increase in oligomer after heat treatment.

Claims (1)

[Claims] (1) A polyethylene terephthalate molded product having an intrinsic viscosity of 0.50 dl/g or more and an oligomer (cyclic trimer) content of 0.55% by weight or less, and in which the polyethylene terephthalate molded product is passed through nitrogen flow. The oligomer increase amount y (wt%) after heating and melting at a temperature of 290 ° C. for 7 minutes is as follows: y≦−0.72x+0.40 [where y is the oligomer increase amount (wt%) after heating] x is the oligomer concentration (% by weight) of the molded body. ] A polyethylene terephthalate molded article.