JP3072939B2 - Copolyester and hollow container and stretched film comprising the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copolymerized polyester useful for bottles, films, sheets and the like. Specifically, since the oligomer content is low and the amount of oligomer by-products during molding is small, not only does it not easily cause contamination of molds and the like during molding, it is also excellent in productivity, heat resistance, mechanical strength, etc. during molding The present invention relates to a copolymerized polyester capable of providing a molded article having excellent productivity during production and a molded article thereof.

[0002]

2. Description of the Related Art Polyethylene terephthalate (hereinafter, referred to as "polyethylene terephthalate")
It is called "PET". ) Is excellent in mechanical strength, chemical stability, transparency, hygiene, etc., and is lightweight and inexpensive, so it is widely used as a packaging material for various sheets and containers, especially carbonated beverages and fruit juices The growth of containers for beverages, liquid seasonings, edible oils, sake, and wine is remarkable.

[0003] In the case of such a PET, for example, in the case of a bottle, a preform for a hollow molded article is molded by an injection molding machine, and the preform is stretch-blown in a mold having a predetermined shape. In addition, in the case of a content liquid that requires heat filling such as a fruit juice beverage, it is common that the liquid is heat-fixed and molded into a bottle in the blow mold or in a separately provided mold. is there.

However, in conventional PET chips used for molding, oligomers are usually contained in an amount of 1 to 2% by weight in a melt-polymerized chip and usually in a solid-state polymerized chip in an amount of 0.5% by weight as a cyclic trimer as a main component. These oligomers adhere to and contaminate equipment such as a mold during molding. The contamination of the mold and the like causes the surface roughness and whitening of the molded product. Therefore, it is necessary to frequently clean the mold and the like.

[0005] Therefore, attempts have been made to lower the oligomers by extending the solid-phase polymerization time or increasing the amount of the catalyst, but the reduction of oligomers by such a method is limited, and economical. Is not a typical way. On the other hand, copolyesters having properties similar to PET, such as copolyesters using terephthalic acid and isophthalic acid as dicarboxylic acid components, and copolyesters using ethylene glycol and diethylene glycol as diol components, are also known. ing. However, copolyesters in which the amount of oligomers is reduced to some extent or less and which have properties equal to or higher than PET have not been specifically known. Further, it is not clear that copolymerization of PET with a small amount of isophthalic acid reduces the oligomer content of the copolymerized polyester obtained by melt polymerization and further solid-phase polymerization as compared with homo-PET. Was.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to reduce the content of oligomers and the amount of by-products of oligomers during molding, so that molds are less likely to be contaminated during molding, and
An object of the present invention is to provide a copolymerized polyester having heat resistance equal to or higher than that of conventional PET, and having high polymerization rate and low oligomer reduction rate during solid-phase polymerization and high productivity.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, have found that a conventional PET contains a small amount of isophthalic acid units and diethylene glycol units in a specific range of physical properties. Polyester was found and reached the present invention. That is, the gist of the present invention is:
The present invention relates to the following copolymerized polyester and a molded article made thereof.

A copolymer polyester containing terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component as main components, (1) 0.5 to 3.0 mol% of isophthalic acid as a dicarboxylic acid component, and (2) 1.0 to 2.5 of diethylene glycol as a diol component
Mol%, (3) intrinsic viscosity is 0.60 to 1.50 dl /
g, (4) the concentration of the terminal carboxyl group is 18 eq / to
(5) The copolymerized polyester, wherein the content of the cyclic trimer is 0.40% by weight or less.

As a method for producing the above-mentioned copolymerized polyester, a method in which the following prepolymer is solid-phase polymerized is preferable. The main components are terephthalic acid as a dicarboxylic acid component, ethylene glycol as a diol component, (1) 0.5 to 3.0 mol% of isophthalic acid as a dicarboxylic acid component, and (2) 1.0 to 2 mol of diethylene glycol as a diol component. 0.5 mol%, (6) intrinsic viscosity is 0.50
(7) A prepolymer having a terminal carboxyl group concentration of 15 to 30 eq / ton.

Hereinafter, the present invention will be described in detail. In the copolymerized polyester of the present invention, for terephthalic acid and ethylene glycol as main components, known raw materials used in PET may be used. As raw materials for isophthalic acid units,
Isophthalic acid, dimethyl isophthalate, esters such as diethyl isophthalate, 5-t-butyl isophthalic acid, alkyl such as 5-methyl isophthalic acid, alkoxy, aryl, aralkyl, a nuclear substituent such as halogen,
Examples thereof include 5-sulfonylisophthalic acid and its sodium salt. Of these, isophthalic acid and dimethyl isophthalate are particularly preferred.

Further, diethylene glycol (hereinafter referred to as "D
EG ". In the case of), ethylene glycol is partially produced as a by-product during the polymerization reaction. Therefore, in addition to using a predetermined amount of DEG or its ester-forming derivative as a raw material for polymerization, reaction conditions, additives, and the like are appropriately selected. Only with this, the content of the DEG component can be controlled. In particular, in the case of the copolymerized polyester of the present invention, by the effect of adding isophthalic acid (hereinafter, referred to as “IPA”),
The melt polymerization temperature can be lowered, and it is easy to keep the amount of DEG by-product low. Examples of the additives include tertiary amines such as triethylamine, tri-n-butylamine and benzyldimethylamine; and quaternary hydroxides such as tetraethylammonium hydroxide, tetrabutylammonium hydroxide and trimethylbenzylammonium hydroxide. A small amount of a basic compound such as ammonium and lithium carbonate, sodium carbonate, potassium carbonate, and sodium acetate can be added to suppress generation of DEG. On the other hand, if a small amount of an inorganic acid such as sulfuric acid is added to the polymerization raw material, the generation of DEG can be promoted and the content can be increased. If necessary, these additives for controlling the amount of DEG produced may be used in an amount of usually 0.001% of the total amount of the polymerization raw material.
It may be used in the range of 10 to 10% by weight, preferably 0.005 to 1% by weight.

In the copolymerized polyester of the present invention, the proportion of IPA in the total dicarboxylic acid component is in the range of 0.5 to 3.0 mol%, preferably 1.0 to 2.5 mol%, and The ratio of DEG in all diol components is 1.0 to 2.
It is in the range of 5 mol%, preferably 1.2 to 2.3 mol%. When the amount is less than the above range, the oligomer reduction rate in the solid-state polymerization step in producing the copolymerized polyester of the present invention is slow, and the effect of reducing the amount of oligomers attached to the mold during molding is small. No superiority over PET is observed. On the other hand, when it exceeds the above range, the heat resistance of the molded article tends to decrease, and the degree of improvement in heat resistance due to the heat fixing effect when the stretch molded article is heat-set is not preferable. In particular, when the amount of IPA exceeds 10 mol%, the glass transition temperature of the copolymerized polyester itself is remarkably reduced, and the heat resistance is considerably reduced.
It is not preferable because the generation of oligomers derived from the product becomes remarkable.

The intrinsic viscosity of the copolymerized polyester of the present invention is phenol / tetrachloroethane (weight ratio 1/1).
0.60 to 1.50 as measured at 30 ° C. in a mixed solvent of
dl / g, preferably 0.65 to 1.20 dl / g, and more preferably 0.70 to 1.00 dl / g. If it is less than 0.60 dl / g, the obtained copolyester cannot have sufficient practical strength when formed into a molded article. In addition, when it exceeds 1.50 dl / g,
The melt viscosity becomes too high, and the amount of sheared heat generated in the molding machine during injection and extrusion molding increases, so a large amount of oligomers once reduced are generated again. As a result, contamination of molds and the like is improved. Not recognized and not preferred.

The oligomer content of the copolymerized polyester of the present invention is 0.40% by weight or less, preferably 0.1% by weight, as the content of the cyclic trimer which is the main component of the oligomer.
It is at most 35% by weight, preferably at most 0.32% by weight, more preferably at most 0.30% by weight. By subjecting the copolymerized polyester having a cyclic trimer content of 0.40% by weight or less to molding, improvement in contamination of a mold and the like is recognized. In general, the lower the cyclic trimer content, the better the contamination of molds and the like. For example, even when the content of the cyclic trimer exceeds 0.35% by weight,
At about 0% by weight, it is hard to say that it is sufficient, but considerable improvement in contamination is observed, and at 0.50% by weight or more, significant contamination is observed. For improvement of contamination of molds, etc.
Whether the content of the monomer is 0.40% by weight or less,
One guide.

Further, the degree of contamination of the mold is closely related to the content of the cyclic trimer of the molded product, and is substantially sufficient when the content of the cyclic trimer of the molded product is 0.40% by weight or less. In particular, when the content is 0.35% by weight or less, the effect of reducing mold contamination is extremely large. At about 0.45% by weight, it is hard to say that it is sufficient, but considerable improvement in contamination is seen, and at 0.55% by weight or more, significant contamination is observed.
For improvement of contamination of a mold or the like, whether or not the content of the cyclic trimer of the molded product is 0.45% by weight or less can be a standard.

The density of the copolymerized polyester of the present invention is usually 1.37 when measured at 25 ° C. by a density gradient tube using a mixed solvent of carbon tetrachloride / n-heptane.
g / cm ³ or more, preferably 1.38 g / cm ³ or more,
More preferably, it is desirable to be 1.39 g / cm ³ or more. If the density is less than 1.37 g / cm ³ ,
Since the amorphous fraction of the copolymerized polyester is high and the solid phase polymerization and heat treatment are insufficient, the oligomer tends to be not sufficiently reduced.

In the copolymerized polyester of the present invention,
Terminal carboxyl group concentration (hereinafter referred to as “AV”)
Is 18 eq / ton or less, preferably 16 eq / to
n or less, more preferably 15 eq / ton or less. In the copolymerized polyester in which the oligomer content is efficiently reduced during the solid-phase polymerization, the AV is in this range, and when the AV is in this range, it adheres to a mold or the like at the time of molding the copolymerized polyester of the present invention. This is more preferable because the effect of reducing oligomers to be formed is greater, and the moisture resistance and thermal stability are improved. If the AV exceeds the above range, the effect of reducing oligomers adhering to a mold or the like during molding is reduced, and the moisture resistance, thermal stability, and the like are undesirably reduced. In the production of the copolymerized polyester of the present invention, the copolymerized polyester subjected to solid-state polymerization is particularly referred to as “prepolymer”. The AV of the copolymerized polyester of the present invention is controlled by the AV of the prepolymer, the conditions for controlling the humidity of the prepolymer, the conditions for crystallization, and the conditions for solid-phase polymerization. For example, AV can be controlled by changing the temperature, time, pressure, etc. of each step such as humidity control, crystallization, and solid phase polymerization of the prepolymer. To illustrate other examples, the AV of the prepolymer is reduced, and the hydrolysis in the crystallization step or the solid-state polymerization step is suppressed by reducing the amount of water impregnated at the time of controlling the humidity of the prepolymer. The AV of the copolymerized polyester of the present invention can be reduced by increasing the concentration of ethylene glycol in the inert gas stream used during the solid phase polymerization. In addition, by increasing the AV of the prepolymer, increasing the amount of water impregnated at the time of controlling the humidity of the prepolymer, or performing crystallization under the introduction of steam, the water in the crystallization step or the solid-state polymerization step is increased. The AV of the copolymerized polyester of the present invention can be increased by accelerating the decomposition or decreasing the concentration of ethylene glycol in the inert gas stream used in the solid phase polymerization.

In the copolymerized polyester of the present invention, the ratio of terminal carboxyl groups to total terminal groups (hereinafter referred to as "A
V / TEV ”) is usually 7 to 25 equivalent%, preferably 8 to 20 equivalent%, and more preferably 10 to 18 equivalent%.
It is desirable that When the AV / TEV is within the above range, the solid-state polymerization rate and the oligomer reduction rate are high in the production, the productivity is further improved, and the oligomer by-product amount during molding is further reduced. Therefore, it is better. This AV / TEV can be controlled by a method similar to the above-described AV.

In general, when PET is produced by solid-phase polymerization, the solid-state polymerization rate (the amount of increase in the intrinsic viscosity per unit time) must be increased in order to increase the productivity to a target intrinsic viscosity in a short time. Is set as fast as possible. It is well known that there is a close relationship between the solid state polymerization rate for PET and AV and AV / TEV, and generally, if the AV is the same, then the AV / TEV When the content is about 30 to 35 equivalent%, the solid-state polymerization rate becomes the highest. The optimum AV for making the solid-state polymerization rate the fastest is the intrinsic viscosity, AV / TEV
Can be automatically determined by the optimal value of

Therefore, in general, AV and AV
Since it is desirable to carry out the solid-state polymerization under such a condition that / TEV is an optimum value at which the solid-state polymerization rate is the fastest,
In conventional solid-phase polymerization products of homo PET or IPA small amount copolymerized PET, AV is usually in the range of about 20 to 35 eq / ton, and AV / TEV is in the range of about 25 to 40 equivalent%.

On the other hand, the present inventors have conducted intensive studies on the rate of oligomer reduction in solid-phase polymerization. As a result, the lower the AV and the lower the AV / TEV, that is, the lower the concentration of the terminal hydroxyl group, It turns out that the higher is, the faster it is. Therefore, when the copolymerized polyester of the present invention is produced by solid-phase polymerization, it is desirable to keep AV and AV / TEV as low as possible from the viewpoint of oligomer reduction in the prepolymer used. . However, as described above, regarding the solid-state polymerization rate, there are optimal values of AV and AV / TEV.
It is necessary to set AV and AV / TEV so that both the solid-state polymerization rate and the oligomer reduction rate are good. However, due to the effect of copolymerizing a small amount of IPA, homo PET
Since the solid-state polymerization rate is fundamentally higher than that of AV and AV / TEV, AV and A /
Even if the solid-state polymerization rate is slightly reduced by lowering V / TEV,
It has a solid-state polymerization rate almost equal to that of general homo PET. Further, the copolymerized polyester of the present invention obtained by solid-phase polymerization already has the target intrinsic viscosity and does not need to be subjected to solid-phase polymerization again, so that AV and AV / TEV are extremely low. It may be something,
Conversely, it is rather preferable because hydrolysis resistance is improved.

When a germanium atom is contained in the copolymerized polyester of the present invention, its content is usually 30 to 6
It is desirably 0 ppm by weight, preferably 35 to 55 ppm by weight, and more preferably 40 to 50 ppm by weight. On the other hand, when an antimony atom is contained, its content is usually 150 to 300 ppm by weight, preferably 17 to 300 ppm by weight.
0-280 ppm by weight, more preferably 200-25
Desirably, it is 0 ppm by weight. When the copolymerized polyester of the present invention contains the same amount of germanium atoms or antimony atoms as compared with homo-PET, the solid-phase polymerization time required to reduce the oligomer content to the same level in the production thereof, if it contains the same amount of germanium atoms or antimony atoms. The productivity is excellent due to the short solid-state polymerization rate and the high solid-phase polymerization rate, the amount of oligomer by-products during molding is small, and the effect of improving mold contamination is enhanced. However, the higher the content of germanium atoms and antimony atoms, the higher the oligomer reduction rate and the faster the solid phase polymerization rate in the production of the copolymerized polyester of the present invention, and the higher the productivity. In this case, the amount of by-products of the oligomer tends to increase. Conversely, the lower the content of germanium atoms and antimony atoms, the lower the amount of oligomers produced during molding, but the lower the productivity during the production of the copolymerized polyester of the present invention. . When the content of germanium atoms or antimony atoms is in the above range, both the productivity in the production of the copolymerized polyester of the present invention and the reduction in the amount of oligomer by-products during molding are greatly improved, so that it is more favorable. It is. The germanium atom and the antimony atom are those derived from a germanium compound or an antimony compound used as a polymerization catalyst of the copolymerized polyester of the present invention described later, which is incorporated into the polymer.

As the thermal properties of the copolymerized polyester of the present invention, the glass transition temperature (Tg) is usually 72 to 82 ° C., preferably 74 to 82 ° C., more preferably 75 to 82 ° C.
And the low-temperature crystallization peak temperature (Tc) is usually 130 to 210 ° C, preferably 150 to 205 ° C,
More preferably, it is desirable to be in the range of 160 to 200 ° C. These Tg and Tc were measured by a differential scanning calorimeter (hereinafter, referred to as “DSC”) by heating 5 mg of the copolymerized polyester sample from room temperature to 285 ° C. at a heating rate of 20 ° C./min. After melting and holding for a minute, the sample is immediately taken out and immersed in liquid nitrogen,
After holding for 1 minute, the sample was allowed to stand at room temperature for 30 minutes to 1 hour, and the sample that had reached room temperature was returned to the apparatus, and was again heated from room temperature at a heating rate of 20 ° C./min. It is determined from the specific heat change behavior due to glass transition and the exothermic behavior due to crystallization. Specifically, Tg is the temperature at the intersection of the tangent at the midpoint of the specific heat change due to the glass transition and the tangent at the point before the specific heat change, and Tc is the heat generation per unit time at the heat generation peak due to crystallization. This is the maximum temperature. When Tg and Tc are in the above-mentioned range, a crystallinity suitable for a normal molding material is obtained, or the heat resistance of a molded product obtained by stretching and heat setting is equal to or higher than that of homo PET. It is easy to do.

The thermal properties of the molded article obtained by injection molding or extrusion molding of the copolymerized polyester of the present invention are as follows.
2 ° C, preferably 74-82 ° C, more preferably 75 ° C
８２82 ° C. and Tc is usually 130-18.
It is desirably in the range of 0 ° C, preferably 130 to 170 ° C, and more preferably 135 to 165 ° C. Tg,
When Tc is in this range, the molded article obtained has appropriate crystallinity as a normal molded article, and after being stretched, heat-set to have a heat resistance equivalent to or higher than that of homo PET. Is easy. In the present copolymerized polyester and its molded product, Tc tends to be generally lower in the molded product. This phenomenon is due to the fact that the shear history at the time of molding remains in the molded article,
This is considered to indicate that the melting operation at about 3 ° C. for about 3 minutes does not completely disappear.

Further, the content of acetaldehyde in the copolymerized polyester of the present invention is usually 7 ppm by weight.
Or less, preferably 5 ppm by weight or less, more preferably 3 ppm by weight or less. When the content of acetaldehyde is in the above range, when the copolymerized polyester of the present invention is formed into a molded article, for example, in a food container such as a bottle, there is no malodor or off-odor derived from acetaldehyde, and This is very preferable because no change in flavor or aroma is observed.

The above-mentioned copolymerized polyester of the present invention comprises P
ET is produced by performing melt polymerization and subsequent solid phase polymerization according to a conventionally known method. Hereinafter, the manufacturing method will be described in detail. As a melt polymerization method, for example, there is a method in which an esterification reaction is directly performed under pressure using terephthalic acid, isophthalic acid, and ethylene glycol, and then the temperature is further increased and the pressure is gradually reduced to perform a polycondensation reaction. Alternatively, it can be produced by performing a transesterification reaction using an ester derivative of terephthalic acid, for example, dimethyl terephthalate, dimethyl isophthalate, and ethylene glycol, and then further polycondensing the obtained reaction product. In these melt polymerization reactions, the isophthalic acid component can be added at any time at the beginning of an esterification reaction, a transesterification reaction, or a polycondensation reaction. For example,
A transesterification reaction between the terephthalic acid ester derivative and ethylene glycol may be performed in advance, and isophthalic acid may be added to the transesterification reaction product for polycondensation. Such a polycondensation reaction may be performed in one stage or may be performed in a plurality of stages. When the polycondensation is carried out in a plurality of stages, the polycondensation reaction conditions are such that the reaction temperature of the first stage polycondensation is usually from 250 to 2
90 ° C., preferably 260 to 280 ° C., and the pressure is usually 500 to 20 mmHg, preferably 200 to 30 mm
Hg, and the temperature of the final polycondensation reaction is usually 2
65-300 ° C, preferably 270-295 ° C,
The pressure is usually 10 to 0.1 mmHg, preferably 5 to 0.1 mmHg.
5 mmHg.

When the polycondensation reaction is carried out in two stages,
The conditions of the polycondensation reaction of the first and second stages are respectively in the above ranges.
This is a condition between the stage and the final stage reaction conditions. For example, when the polycondensation reaction is carried out in three stages, the reaction temperature of the second stage polycondensation reaction is usually from 260 to 295C, preferably from 270 to 285C, and the pressure is usually from 50 to 2C.
mmHg, preferably in the range of 40-5 mmHg.
The intrinsic viscosity reached in each of these polycondensation reaction steps is not particularly limited, but it is preferable that the degree of increase in the intrinsic viscosity in each stage is smoothly distributed, and further from the final stage polycondensation reactor. The intrinsic viscosity of the obtained prepolymer is usually 0.45 to 0.80 dl / g, preferably 0.50 to 0.70 dl / g, and more preferably 0.50 to 0.65 dl / g. If the intrinsic viscosity of the prepolymer is less than the above range, it becomes difficult to form chips, and if the intrinsic viscosity is more than the above range, it is difficult to extract the prepolymer from the reaction vessel, and the effect of reducing oligomers when subjected to solid phase polymerization. Is reduced. Usually, the prepolymer is withdrawn from the molten state into strands and then cut into granular chips.

Such a granular chip usually has a particle size of 2.0 to
It is desirable to have an average particle size of 5 mm, preferably 2.2-4.0 mm. In the above esterification reaction, transesterification reaction and polycondensation reaction, it is preferable to use necessary amounts of an esterification catalyst, a transesterification catalyst, a polycondensation catalyst, a stabilizer and the like.

Since the terephthalic acid and isophthalic acid used are autocatalysts in the esterification reaction, there is no particular need to use an esterification catalyst, but if necessary, for example, a small amount of an inorganic acid or the like may be used. it can. As the transesterification catalyst, known compounds generally used for PET, for example, one or more of calcium, titanium, manganese, zinc, sodium and lithium compounds can be used. Is particularly preferred.

As the polycondensation catalyst, known compounds generally used for PET, for example, one or more compounds such as germanium, antimony, titanium and cobalt compounds can be used. Preferably, a compound of germanium or antimony is used. use. Further, when the transparency of the obtained copolyester is very important, a germanium compound is more preferably used. Examples of the compound of germanium or antimony include oxides, inorganic acid salts, organic acid salts, halides, and sulfides thereof.

The amount of the catalyst is usually 5 to 20 in the total amount of the polymerization raw materials in terms of the amount of metal for both the transesterification catalyst and the polycondensation catalyst.
It is used in the range of 00 ppm by weight, preferably 10 to 500 ppm by weight. In particular, when a germanium compound is used, the amount used is such that the content of germanium atoms in the produced prepolymer or copolymerized polyester after solid-phase polymerization is usually 10 to 100 ppm, preferably 30 to 100 ppm.
60 weight ppm, more preferably 35-55 weight pp
It is desirable to use an appropriate amount so as to be in the range of m, more preferably 40 to 50 ppm by weight. When an antimony compound is used, the amount of the antimony compound used in the prepolymer to be produced or the copolymerized polyester after solid-phase polymerization is as follows:
The content of antimony atoms is usually 150 to 300 weight p
pm, preferably 170 to 280 ppm by weight, more preferably 200 to 250 ppm by weight. When the content of germanium atoms or antimony atoms is within the above range, the oligomer reduction rate and solid-state polymerization rate when producing a copolymerized polyester by solid-state polymerization of a prepolymer, and the oligomer secondary rate during molding are reduced. Since the reduction of the production amount is further increased, it is better. In order to satisfy the range, for example, when using germanium dioxide, usually about 50 to 300 ppm by weight of germanium dioxide with respect to the polymer, when using antimony trioxide, usually,
About 180 to 1000 ppm by weight of antimony trioxide is used at the time of melt polymerization with respect to the polymer, but depending on the temperature, pressure, polymerization time and the ratio of the dicarboxylic acid component to the glycol component of the esterification reactant, etc. Can also control its content.

Examples of the stabilizer include phosphates such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate and tricresyl phosphate, triphenyl phosphite, trisdodecyl phosphate, and the like. Phosphites such as trisnonylphenyl phosphite, acid phosphates such as methyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, dioctyl phosphate, and phosphoric acid, phosphorous acid, and the like Phosphorus compounds such as phosphorous acid and polyphosphoric acid are preferred. The stabilizer is usually used in an amount of 10 to 100 as a weight of phosphorus atoms in the stabilizer, in all the polymerization raw materials.
It is used in an amount of 0 ppm by weight, preferably 20 to 200 ppm by weight. In particular, when a germanium compound is used as the polycondensation catalyst, the phosphorus atom contained in the prepolymer and the copolymerized polyester after the solid-phase polymerization,
In weight ratio to germanium atoms also contained,
Usually, it is desirable to use it in a range of 0.3 to 1.5 times, preferably 0.4 to 1.0 times. When the phosphorus atom content is within this range, the prepolymer and the copolymerized polyester obtained by solid-phase polymerization thereof have good thermal stability, and the prepolymer is produced by solid-phase polymerization to produce a copolymerized polyester. This is more preferable because the rate of oligomer reduction during the process is further increased.

Further, a small amount of a dicarboxylic acid component other than terephthalic acid and isophthalic acid and a diol component other than ethylene glycol and diethylene glycol may be contained as long as the constitutional requirements of the present invention are not deviated. These dicarboxylic acid components include phthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid,
Examples of 1,3-phenylenedioxydiacetic acid and their structural isomers, aliphatic dicarboxylic acids such as malonic acid, succinic acid, and adipic acid, oxyacids and derivatives thereof include p-hydroxybenzoic acid and p-hydroxy acid. Benzoic acid esters, glycolic acid and the like can be mentioned. As the diol component, 1,2-propanediol, 1,1,
Aliphatic glycols such as 3-propanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol and neopentyl glycol; alicyclic glycols such as cyclohexanedimethanol; and aromatics such as bisphenol A and bisphenol S Group dihydroxy compound derivatives.

As described above, the composition (structural unit) of the prepolymer produced by melt polymerization and the content of germanium atoms, antimony atoms, phosphorus atoms and the like are determined according to the present invention obtained by subjecting the prepolymer to solid-state polymerization. Although substantially the same as the copolymerized polyester, more specifically, the content of these germanium atoms, antimony atoms, phosphorus atoms, etc., depends on the conditions during solid-phase polymerization, such as temperature, time, pressure and inert gas. Depending on the conditions such as the flow rate, the amount of each of these atoms of the prepolymer may decrease by about 0 to 10% during the solid phase polymerization.

The AV of the prepolymer is usually 10
~ 40 eq / ton, preferably 15 ~ 30 eq / to
n, more preferably in the range of 18 to 25 eq / ton. When the AV is within the above range, the solid-state polymerization rate when the prepolymer is subjected to solid-state polymerization is high, and the effect of reducing oligomers is large, which is very preferable. When the amount is less than the above range, the solid phase polymerization is poor, and it takes a long time to increase the intrinsic viscosity. The reduction effect may be small.

Further, the AV / TEV of the prepolymer is:
Usually 10 to 25 equivalent%, preferably 12 to 22 equivalent%,
More preferably, it is desirable to be in the range of 14 to 20 equivalent%. When the ratio of the terminal carboxyl group to the total terminal groups is within the above range, the solid-state polymerization rate and the oligomer reduction rate when the prepolymer is subjected to solid-state polymerization are high, and the productivity is further improved. In addition, the amount of oligomer by-products during molding can be further reduced, so that it is more favorable.

The AV and AV / T of these prepolymers
EV is controlled by controlling the AV and AV / TEV conventionally performed by PET melt polymerization, for example, the final esterification rate during the esterification reaction, the temperature and pressure during the transesterification reaction and the polycondensation reaction, and the like. It can be performed by controlling time or the like. The final esterification rate during the esterification reaction is not only the temperature, pressure and time of the esterification reaction, but also other
For example, it can also be controlled by the charging ratio of the diol and the dicarboxylic acid, the reaction product water and the diol return rate (or distillation rate), and the like. As a more specific example, ordinary PET
Using a continuous melt polymerization facility used to produce the direct polycondensation method, the case where the production of the prepolymer for the copolymerized polyester of the present invention is shown, the reaction time during the esterification reaction is increased. Although there is a method of increasing the final esterification rate and lowering the AV and AV / TEV of the prepolymer, it is more preferable to set the ethylene glycol distillation rate higher than in the case of ordinary PET, or to perform the esterification reaction. By setting the temperature higher, the final esterification rate is increased, and the AV and AV /
Lowering the TEV is desirable in terms of prepolymer productivity. The AV and AV / TEV of the prepolymer immediately before being subjected to the solid-phase polymerization are controlled not only during the melt polymerization of the prepolymer as described above, but also as described above under the humidity control condition and the crystallization condition of the prepolymer. It can also be controlled by appropriately selecting the above.

Next, in order to obtain the copolymerized polyester of the present invention, it is necessary to further subject the prepolymer chip obtained by the above-mentioned melt polymerization to a solid phase polymerization treatment. The prepolymer chips subjected to solid-state polymerization are made to absorb moisture under an atmosphere of water, water vapor or a water vapor-containing inert gas,
It may be humidified, or it may be heated to a temperature lower than the temperature at which the solid-phase polymerization is carried out in advance and pre-crystallized, and then supplied to the solid-phase polymerization condensation step. In such a pre-crystallization step, the prepolymer chips are dried in a dry state, usually at 120 to 200 ° C, preferably at 130 to 180 ° C.
C. for about 1 minute to 4 hours. Alternatively, the chip may be heated to a temperature of 120 to 200.degree. C. for 1 minute or more under an atmosphere of steam or an inert gas containing steam. Further, the prepolymer chip may be subjected to moisture absorption in an atmosphere of water, water vapor or a water vapor-containing inert gas, and the humidity-conditioned prepolymer chip may be heated to a temperature of usually 120 to 200 ° C. for 1 minute or more. The humidity control of the prepolymer is carried out such that the water content of the prepolymer is usually in the range of 0.01 to 1% by weight, preferably 0.1 to 0.5% by weight. By subjecting the prepolymer chip containing water to a crystallization step or a solid-state polymerization step, the amount of acetaldehyde contained in the copolymerized polyester of the present invention can be further reduced.

The solid-state polymerization step in which the above-mentioned prepolymer chips are supplied comprises at least one stage, and the polymerization temperature is usually 190 to 230 ° C., preferably 195 to 225.
° C, and in the case of the inert gas flow method, the pressure is usually 1 kg.
/ Cm ² G to 10 mmHg, preferably 0.5 kg /
It is carried out under a condition of cm ² G to 100 mmHg under a flow of an inert gas such as nitrogen, argon, carbon dioxide, etc., and in a reduced pressure method, the pressure is usually 0.01 to 300 mmHg, preferably 0.01 to 100 mmHg. Will be implemented. The solid-state polymerization time reaches a desired property in a shorter time as the temperature is higher, but is usually 1 to 50 hours, preferably 5 to 3 hours.
0 hour, more preferably 10 to 25 hours.

The copolymer polyester of the present invention can be obtained by appropriately selecting the conditions for the above solid phase polymerization treatment. The polyester of the present invention thus obtained can be used to form films, sheets, containers, and other packaging materials by using a melt molding method generally used for PET. Further, the mechanical strength can be improved by stretching the copolymerized polyester at least in a uniaxial direction.

In producing a stretched film, the stretching temperature may be set between the glass transition temperature of the copolymerized polyester of the present invention and a temperature 70 ° C. higher than that, usually 40 to 170 ° C., preferably 60 to 140 ° C. ° C. The stretching may be uniaxial or biaxial, but is preferably biaxial in view of practical physical properties of the film. The stretching ratio is usually 1.1 to 10 times, preferably 1.5 to 10 times in the case of uniaxial stretching.
In the case of biaxial stretching, the stretching may be performed in the range of usually 1.1 to 8 times, preferably 1.5 to 5 times in both the longitudinal and transverse directions. Also, the vertical magnification /
The lateral magnification is usually 0.5-2, preferably 0.7-1.
3. The obtained stretched film can be further heat-set to improve heat resistance and mechanical strength. The heat setting is usually performed under a tension of 120 to melting point, preferably 150 to
The reaction is usually performed at 230 ° C. for several seconds to several hours, preferably for several tens seconds to several minutes.

In producing the hollow molded article, a preform formed from the copolymerized polyester of the present invention is stretch blow-molded, and an apparatus conventionally used in PET blow molding can be used. . Specifically, for example, a preform is once molded by injection molding or extrusion molding, and then, as it is, or after processing the plug portion and the bottom portion, it is reheated, and biaxial stretching such as a hot parison method or a cold parison method is performed. A blow molding method is applied. In this case, the molding temperature, specifically, the temperature of each part of the cylinder of the molding machine and the temperature of the nozzle can be set within a range of 260 to 280 ° C., which is 1 to 10 ° C. lower than that of general PET, and the amount of oligomer can be kept low. Is easy. In addition, the decrease in intrinsic viscosity can be suppressed low, and the amount of by-product acetaldehyde can be easily suppressed low.
The stretching temperature is usually 70 to 120 ° C, preferably 80 to 1 ° C.
At 10 ° C., the stretching ratio is usually 1.5 to 3.5 in the longitudinal direction.
It is sufficient to carry out in the range of 2 to 5 times in the circumferential direction.

The obtained hollow molded article can be used as it is. In particular, in the case of a content liquid that requires heat filling such as a fruit juice drink, oolong tea, etc., it is generally heat-fixed in a blow mold. Further, it is used by imparting heat resistance.
The heat setting is usually performed under a tension of, for example, compressed air, 100 to 200.
C., preferably at 120 to 180.degree. C., for several seconds to several hours, preferably for several seconds to several minutes.

[0044]

EXAMPLES Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist. In this example,
“Parts” means “parts by weight”. Various measurement methods used in this example are shown below. The methods for measuring the intrinsic viscosity and the density are as described above.

(1) Amount of isophthalic acid (hereinafter referred to as “IPA amount”)
After methanol decomposition by a conventional method, the resulting dimethyl ester component was quantified by gas chromatography.

(2) Diethylene glycol amount (hereinafter referred to as “D
The amount of the diol compound produced by hydrolysis according to a conventional method was determined by gas chromatography.

(3) Content of cyclic trimer (hereinafter referred to as “CT amount”)
200 mg of a sample was dissolved in 2 ml of a mixed solution of chloroform / hexafluoroisopropanol (volume ratio: 3/2), and further diluted with 20 ml of chloroform. to this,
10 ml of methanol was added to reprecipitate the sample, followed by filtration to obtain a filtrate. After the filtrate was dried, the residue obtained by dissolving the residue in 25 ml of dimethylformamide was analyzed and quantified by liquid chromatography.

(4) Terminal carboxyl group concentration (hereinafter referred to as “A
V ". ) 100 mg of the copolyester sample was dissolved by heating in 5 ml of benzyl alcohol, diluted with 5 ml of chloroform, and diluted with phenol red as an indicator.
It was titrated with an N-sodium hydroxide / benzyl alcohol solution and quantified.

(5) Total terminal group concentration (hereinafter referred to as “TEV”) The concentration was calculated from the intrinsic viscosity using the following equation. TEV = $ 200000 / (1359 x intrinsic viscosity)
^1.460 (unit: eq / ton).

(6) Ratio of terminal carboxyl groups to total terminal groups (hereinafter referred to as “AV / TEV”) A value obtained by dividing AV by TEV was multiplied by 100 and expressed as a percentage (unit: equivalent%).

(7) Germanium atom content (hereinafter referred to as “G
e) 2.0 g of a copolymerized polyester sample was incinerated in the presence of sulfuric acid by a conventional method, completely decomposed, and the volume was adjusted to 100 ml with distilled water.

(8) Antimony atom content (hereinafter referred to as “Sb
The amount was determined by emission spectroscopy in the same manner as in the analysis of the germanium atom content.

(9) Phosphorus atom content (hereinafter referred to as "P amount") Quantification was performed by emission spectroscopy in the same manner as in the analysis of germanium atom content.

(10) Glass transition temperature (Tg) and low-temperature crystallization temperature (Tc) The above-mentioned method was carried out using a SEIKO I & E, SSC / 580 (DSC20) type differential scanning calorimeter (manufactured by Seiko Instruments Inc.). Was measured by

(11) Acetaldehyde content (hereinafter referred to as “AA content”) After extraction with water at 160 ° C. for 2 hours, the content was determined by gas chromatography.

(12) Solid-state polymerization rate The intrinsic viscosity per unit time during solid-state polymerization obtained by dividing the difference between the intrinsic viscosity of the solid-phase polymerization product and the intrinsic viscosity of the prepolymer by the solid-state polymerization time. The rate of increase was defined as the solid-state polymerization rate (unit: dl / g / hr).

(13) Inert gas flow rate The inert gas flow rate is defined as 1 atmosphere, 25 ° C., per unit time (hr) and per unit resin weight (kg).
It was shown by volume (L) converted to.

Production Example of Prepolymer Production Example 1 A slurry of 12560 parts of terephthalic acid, 394 parts of isophthalic acid, and 5820 parts of ethylene glycol was prepared, and 300 parts of bis (2-hydroxyethyl) terephthalate was added in advance, and 250 ° C. Was sequentially supplied to the esterification tank held for 4 hours. After the completion of the supply, the mixture was further maintained at 250 ° C. for 1 hour to allow the esterification reaction to proceed. Then, half of the mixture was transferred to a polycondensation tank, and 1.14 parts of phosphoric acid (based on 150 ppm by weight of polymer) and 0.91 parts of germanium dioxide were added. (120 ppm by weight of polymer)
The temperature was gradually increased from 250 ° C. to 280 ° C., and the pressure was gradually reduced from normal pressure, and the pressure was maintained at 0.5 mmHg. Reaction 3
After performing for a time, the formed prepolymer is drawn out in a strand form from a discharge port provided at the bottom of the polycondensation tank, and after water cooling,
It was cut into chips. Table 1 shows the analysis results of the prepolymer chip.

Production Example 2 A prepolymer chip was obtained in the same manner as in Production Example 1, except that 12700 parts of terephthalic acid and 263 parts of isophthalic acid were used. Table 1 shows the analysis results of the prepolymer chip.
Shown in

Production Example 3 197 parts of isophthalic acid and 1.1 parts of germanium dioxide
0 parts except that (to polymer 145 wt ppm) was used, manufactured
In the same manner as forming Example 2, to obtain a prepolymer chips. Table 1 shows the analysis results of the prepolymer chip.

Production Example 4 14850 parts of dimethyl terephthalate, 150 parts of dimethyl isophthalate, 10600 parts of ethylene glycol and 2.60 parts of manganese acetate tetrahydrate (vs. polymer 175p
pm) into a reaction vessel, and 4 ° C. from 160 ° C. to 220 ° C.
The temperature was gradually raised over time, and the transesterification reaction was carried out while distilling off the methanol generated during the process. To this reaction were added 2.67 parts of phosphoric acid (180 ppm by weight of polymer), 1.78 parts of germanium dioxide ( 120 parts by weight of polymer
m), and finally, at 275 ° C. and 0.5 mmHg, the polymerization time was set to 3 hours to obtain a prepolymer chip. Table 1 shows the analysis results of the prepolymer chip.

Production Example 5 1.90 parts of phosphoric acid (250 ppm by weight based on polymer)
1. Antimony trioxide is used instead of germanium dioxide.
A prepolymer chip was obtained in the same manner as in Production Example 2, except that 74 parts (based on 360 ppm by weight of the polymer) was used and the polymerization time was changed to 2.5 hours. Table 1 shows the analysis results of the prepolymer chip.

Production Example 6 1.06 parts of phosphoric acid (140 ppm by weight based on polymer)
A prepolymer chip was obtained in the same manner as in Production Example 5, except that 2.36 parts of antimony trioxide (310 wt ppm relative to the polymer) was used. Table 1 shows the analysis results of the prepolymer chip.

Production Example 7 A prepolymer chip was obtained in the same manner as in Production Example 5, except that the esterification reaction time after the feed of the raw slurry was completed was 1 hour and 30 minutes. Table 1 shows the analysis results of the prepolymer chip.

Production Example 8 A prepolymer chip was obtained in the same manner as in Production Example 5, except that the esterification reaction time after the feed of the raw material slurry was completed was 40 minutes. The analysis results of the prepolymer chips shown in Table 1.

Production Example 9 A transesterification reaction was carried out in the same manner as in Production Example 4, except that 14,800 parts of dimethyl terephthalate, 225 parts of dimethyl isophthalate, and 9600 parts of ethylene glycol were used. The reaction product was charged with cobalt acetate tetrahydrate 1.26.
Parts (85 ppm by weight of polymer), 1.80 parts of phosphoric acid (120 ppm by weight of polymer), and 4.30 parts of antimony trioxide (290 ppm by weight of polymer) instead of germanium dioxide. In the same manner as in Production Example 4, a prepolymer chip was obtained. Table 1 shows the analysis results of the prepolymer chip.

Production Example 10 130 parts of isophthalic acid, 1.29 parts of phosphoric acid (170 wt ppm based on polymer), and 2.60 of antimony trioxide
A prepolymer chip was obtained in the same manner as in Production Example 5 except that the same amount was used (345 ppm by weight with respect to the polymer). Table 1 shows the analysis results of the prepolymer chip.

Production Example 11 A prepolymer chip was obtained in the same manner as in Production Example 2 except that no isophthalic acid was added. Table 1 shows the analysis results of the prepolymer chip.

Production Example 12 A prepolymer chip was obtained in the same manner as in Production Example 5 except that no isophthalic acid was added. Table 1 shows the analysis results of the prepolymer chip.

Production Example 13 A prepolymer chip was obtained in the same manner as in Production Example 2 except that 12,500 parts of terephthalic acid and 814 parts of isophthalic acid were used. Table 1 shows the analysis results of the prepolymer chip.
Shown in

Production Example 14 A prepolymer chip was obtained in the same manner as in Production Example 2 except that 350 parts of diethylene glycol was added to the prepared slurry. Table 1 shows the analysis results of the prepolymer chip.

Production Example 15 A prepolymer chip was obtained in the same manner as in Production Example 2 except that the esterification reaction time after the feed of the raw material slurry was completed was shortened to 30 minutes. Table 1 shows the analysis results of the prepolymer chip.

Production Example 16 A prepolymer chip was obtained in the same manner as in Production Example 5, except that the esterification reaction time after the feed of the raw material slurry was completed was shortened to 30 minutes. Table 1 shows the analysis results of the prepolymer chip.

Production Example 17 A prepolymer chip was obtained in the same manner as in Production Example 2 except that 0.45 parts of germanium dioxide (65 ppm by weight with respect to the polymer) was used. Table 1 shows the analysis results of the prepolymer chip.

Production Example 18 0.674 parts of phosphoric acid (90 ppm by weight based on polymer)
1. Antimony trioxide was used instead of germanium dioxide.
Except for using 37 parts (180 ppm by weight of polymer),
A prepolymer chip was obtained in the same manner as in Production Example 2. Table 1 shows the analysis results of the prepolymer chip.

Example 1 The surface of the prepolymer chip obtained in Production Example 1 was crystallized at 150 ° C. with a stirring crystallization machine (Bepex) and then transferred to a stationary solid-state polymerization tower. Liter / kg / h
After drying at 150 ° C for 3 hours under a nitrogen flow of r, 208 ° C
For 20 hours to obtain a solid-phase polymerization chip. Table 2 shows the analysis results of the solid-phase polymerization chip.

Examples 2 to 13 Using the prepolymer chips obtained in Production Examples 1 to 10,
As in Example 1 , at 208 ° C. or 215 ° C., 2
Solid phase polymerization was performed for 0 hours to obtain a solid phase polymerization chip. Table 2 shows the analysis results of the solid-phase polymerization chip.

Comparative Examples 1 to 10 Using the prepolymer chips obtained in Production Examples 11 to 18 , solid-state polymerization was carried out at 208 ° C. for 20 hours or 30 hours in the same manner as in Example 1 to obtain solid-state polymerized chips. Obtained. Table 2 shows the analysis results of the solid-phase polymerization chip.

Example 14 Using the solid-phase polymerization chip obtained in Example 1 , the temperature of each part of the cylinder and the nozzle head was increased to 270 ° C., the screw rotation speed was set to 100 rpm, the injection time was set to 10 seconds, and the mold cooling water temperature was set to 10 ° C. The preform was molded with the set IS-60B injection molding machine manufactured by Toshiba Corporation. The plug portion of this preform was heated and crystallized by a self-made crystallizer, and then blow-molded by a stretch blow molding machine set at a preheating furnace temperature of 90 ° C., a blow pressure of 20 kg / cm ² and a molding cycle of 10 seconds. A bottle having an average wall thickness of 300 μm and an internal volume of 1 liter was then placed in a mold set at 150 ° C. under pressure and air tension.
Heat set for seconds. Table 3 shows the analysis results of the heat-fixed bottle.

As a continuous molding test, 1,000 bottles were continuously molded, and no contamination was observed in any of the injection, blowing, and heat setting dies. Further, as a heat filling test, orange juice liquid sterilized at 90 ° C. and allowed to cool to 85 ° C. was filled in the heat-fixed bottle, and the bottle was deformed after being inverted for 15 minutes after sealing. No deformation of the plug, shoulder, torso, etc. was observed.

Examples 15 to 25 Using the solid-phase polymerization chips obtained in Examples 3 to 13 , the temperature of each part of the cylinder and the nozzle head of the injection molding machine was adjusted to 2
A heat set bottle was formed in the same manner as in Example 14 except that the temperature was changed to 65 ° C or 275 ° C. Table 3 shows the analysis results of the bottle. Further, the same continuous molding test as in Example 14 was performed,
Observation of the mold after molding revealed that no contamination was observed in any of the injection, blowing, and heat-fixing molds when any of the solid-phase polymerization chips was used. Further, the embodiment
A heat-filling test was performed in the same manner as in No. 14 , but none of the heat-fixing bottles using any of the solid-state polymerization chips showed any liquid leakage or deformation of the plug, shoulder, and trunk.

Comparative Examples 11 to 22 Using the solid-phase polymerization chips obtained in Comparative Examples 1 to 10 , the temperature of each part of the cylinder and the nozzle head of the injection molding machine was adjusted to 2
A heat set bottle was formed in the same manner as in Example 14 except that the temperature was changed to 70 ° C or 275 ° C. Table 3 shows the analysis results of the bottle.

When the solid-state polymerization chips of Comparative Examples 2 and 4 were used and injection molding was performed with the temperature of each part of the cylinder and the nozzle head set at 270 ° C., only a whitened preform was obtained. Molding could not be performed. It is considered that the reason for this is that the solid-state polymerization chip had a high melting point because the isophthalic acid component was not copolymerized, and could not be completely melted at an injection molding temperature of 270 ° C.

Further, the same continuous molding test as in Example 14 was performed, and the mold after molding was observed. When the solid-phase polymerization chip of Comparative Example 5 was used, no contamination was observed in any of the injection, blowing, and heat-fixing molds. Comparative Example 5
When solid-state polymerization chips other than those described above were used, white thin film-like deposits were observed in all cases, though varying in degree. Visual observation showed that the higher the content of the cyclic trimer in the molded product, the more the mold was contaminated.

Further, the same heat filling test as in Example 14 was performed. Comparative Example 5 obtained in the solid-phase polymerization chips, and the heat bottle molded using the solid-phase polymerization chips obtained in Comparative Example 6, with the shoulder portion and the barrel portion is greatly deformed, the mouth part Liquid leakage was observed. In heat-fixed bottles using solid-state polymerization chips other than Comparative Examples 5 and 6 , no liquid leakage or deformation of the plug, shoulder, and trunk was observed at all.

Example 26 Using the solid-phase polymerization chip obtained in Example 3 , the temperature of each part of the cylinder and each part of the nozzle was set to 275 ° C., the number of revolutions of the screw was set to 40 rpm, and the extrusion rate was set to 30 g / min.
A sheet having a thickness of 300 μm was formed by a mmφ extruder. Extrusion was continued for 10 hours continuously, and almost no contamination of the cooling drum was observed. Further, the extruded sheet was set to a long biaxial stretching machine (TM.
Long 3) at the same time, and heat-set at 200 ° C. for 120 seconds in an oven under tension.
A 0 μm thick stretched film was obtained. Table 4 shows the analysis results of the film.

Examples 27 to 30 Using the solid-state polymerization chips obtained in Examples 3 , 6 , 8 , and 12 , the temperature of each part of the cylinder and each part of the nozzle was raised to 270 ° C. or 275 ° C. In the same manner as in Example 26 , a sheet having a thickness of 300 μm was formed. The extrusion molding was continuously performed for 10 hours, but when any of the solid-phase polymerization chips was used, a transparent sheet could be molded favorably and contamination of the cooling drum was hardly observed. Further, using these extruded sheets,
In the same manner as in Example 26 , a heat-set biaxially stretched film having a thickness of 30 µm was obtained. Table 4 shows the analysis results of the film.

Comparative Examples 23 to 24 Using the solid-phase polymerization chip obtained in Comparative Example 1 , the temperature of each part of the cylinder and each part of the nozzle was set to 270 ° C. or 27 ° C.
The temperature was set to 5 ° C., and a sheet having a thickness of 300 μm was formed in the same manner as in Example 26 . When the temperature of each part of the cylinder and each part of the nozzle was set to 275 ° C., a transparent sheet was obtained.
White thin film-like deposits were observed on the cooling drum. Further, using this extruded sheet, a heat-set biaxially stretched film having a thickness of 30 μm was obtained in the same manner as in Example 26 . Table 4 shows the analysis results of the film. On the other hand, when the temperature of each part of the cylinder and each part of the nozzle was 270 ° C., a whitened sheet was obtained, and good molding could not be performed. It is considered that the reason for this is that the solid-state polymerization chip had a high melting point because the isophthalic acid component was not copolymerized, and could not be completely melted at an injection molding temperature of 270 ° C.

As shown in the above examples, the copolymerized polyester of the present invention has a low oligomer content and a small amount of oligomer by-products during molding. In addition, since molding can be performed at a lower temperature than homo PET, the amount of oligomer by-products during molding can be further reduced. Therefore, when the copolymerized polyester of the present invention is molded, mold contamination does not easily occur, so that it is not necessary to frequently clean the molding apparatus when producing molded articles, and it is possible to mold bottles, films, sheets, and the like. Product productivity can be improved. In addition, the copolymerized polyester of the present invention is excellent in heat resistance, mechanical strength, and the like, and is suitable as a molding material for a fruit juice beverage container that requires heat resistance.

Further, the copolymerized polyester of the present invention comprises
In the solid-state polymerization step of the production process, the rate of decrease in the content of the oligomer is high, so that not only can the target oligomer content be reduced in a short time compared to the conventional homo PET, but also the extreme Since the rate of increase in viscosity is high, the desired intrinsic viscosity can be achieved in the same or shorter time as the conventional homo-PET, resulting in extremely high productivity.

[0091]

[Table 1]

[0092]

[Table 2]

[0093]

[Table 3]

[0094]

[Table 4]

[0095]

[Table 5]

[0096]

[Table 6]

[0097]

[Table 7]

[0098]

The copolymerized polyester of the present invention has a low oligomer content and a small amount of oligomer by-products during molding. In addition, since molding can be performed at a lower temperature than homo PET, the amount of oligomer by-products during molding can be further reduced. Therefore, when the copolymerized polyester of the present invention is molded, mold contamination does not easily occur, so that it is not necessary to frequently clean the molding apparatus when producing molded articles, and it is possible to mold bottles, films, sheets, and the like. Product productivity can be improved. In addition, the copolymerized polyester of the present invention is excellent in heat resistance, mechanical strength, and the like, and is suitable as a molding material for a fruit juice beverage container that requires heat resistance.

Further, the copolymerized polyester of the present invention comprises:
In the solid-state polymerization step of the production process, the rate of decrease of the oligomer content is high, so that compared to the conventional homo PET,
Not only can the desired oligomer content be obtained in a short period of time, but also the intrinsic viscosity can be increased to a target intrinsic viscosity equivalent to or shorter than conventional homo-PET because of the rapid increase in intrinsic viscosity. , Very productive.

From the above points, the copolymerized polyester of the present invention has high industrial value.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI B29K 67:00 B29L 7:00 22:00 C08L 67:00 (72) Inventor Kazushi Matsumoto 1000 Kamoshidacho Midori-ku, Yokohama-shi, Kanagawa Inside Mitsubishi Chemical Research Laboratory (72) Inventor Takuji Hirahara 1000 Kamoshita-cho, Midori-ku, Yokohama, Kanagawa Prefecture Inside Mitsubishi Chemical Research Laboratory (72) Inventor Osamu Kishiro 1000 Kamoshida-cho, Midori-ku, Yokohama, Kanagawa Prefecture Mitsubishi (56) References JP-A-58-189227 (JP, A) JP-A-57-16024 (JP, A)

Claims (8)

(57) [Claims] 1. A terephthalic acid as a dicarboxylic acid component,
A copolymerized polyester containing ethylene glycol as a main component as a diol component, wherein (1) isophthalic acid is 0.5 to 3.0 mol% as a dicarboxylic acid component, and (2) diethylene glycol is 1.0 to 2 as a diol component. .
5 mol%, (3) intrinsic viscosity is 0.60 to 1.50 dl /
g, (4) the concentration of the terminal carboxyl group is 18 eq / to
(5) The copolymerized polyester, wherein the content of the cyclic trimer is 0.40% by weight or less. 2. The copolymer polyester according to claim 1, wherein the ratio of the terminal carboxyl group to the total terminal groups is 7 to 25 equivalent% . 3. The copolymerized polyester according to claim 1, wherein the content of the cyclic trimer is 0.35% by weight or less. 4. A terephthalic acid as a dicarboxylic acid component,
As a diol component, ethylene glycol is used as a main component,
(1) Isophthalic acid is 0.5 to 0.5 as a dicarboxylic acid component.
3.0 mol%, (2) 1.0 to 2.5 mol% of diethylene glycol as a diol component, (6) intrinsic viscosity of 0.50 to 0.70 dl / g, (7) concentration of terminal carboxyl group of 15 (1) Isophthalic acid as a dicarboxylic acid component is 0.5 to 30 eq / ton.
3.0 mol%, (2) 1.0 to 2.5 mol% of diethylene glycol as a diol component, (3) intrinsic viscosity of 0.60 to 1.50 dl / g, (4) concentration of terminal carboxyl group of 18 eq. / Ton or less, (5) a copolymerized polyester having a cyclic trimer content of 0.40% by weight or less. 5. The copolyester according to claim 4, which is produced by solid-phase polymerization of a prepolymer having a ratio of terminal carboxyl groups to total terminal groups of 10 to 25 equivalent%. 6. A terephthalic acid as a dicarboxylic acid component,
A copolymerized polyester containing ethylene glycol as a main component as a diol component, wherein (1) isophthalic acid is 0.5 to 3.0 mol% as a dicarboxylic acid component, and (2) diethylene glycol is 1.0 to 2 as a diol component. .
5 mol%, (3) intrinsic viscosity is 0.60 to 1.50 dl /
g, (4) the concentration of the terminal carboxyl group is 18 eq / to
n or less, and (5) a preform formed by injection molding or extrusion molding of a copolymerized polyester characterized in that the content of the cyclic trimer is 0.40% by weight or less. And a hollow container made of the copolymerized polyester. 7. A terephthalic acid as a dicarboxylic acid component,
A copolymerized polyester containing ethylene glycol as a main component as a diol component, wherein (1) isophthalic acid is 0.5 to 3.0 mol% as a dicarboxylic acid component, and (2) diethylene glycol is 1.0 to 2 as a diol component. .
5 mol%, (3) intrinsic viscosity is 0.60 to 1.50 dl /
g, (4) the concentration of the terminal carboxyl group is 18 eq / to
n or less, and (5) a sheet made of a copolymerized polyester obtained by injection molding or extrusion molding of the copolymerized polyester, wherein the content of the cyclic trimer is 0.40% by weight or less. 8. A stretched film made of a copolyester obtained by stretching the sheet material according to claim 7 in at least one direction.