JPH08113631A - Polyester copolymer and packaging material and packaging container made thereof - Google Patents

Abstract

PURPOSE: To obtain a polyester copolymer having heat resistance and hot-water resistance by mixing two reaction products obtained by the transesterification of a combination of a lower-alkyl 2,6-naphthalenedicarboxylate etc. with each other and polycondensing the obtained mixture. CONSTITUTION: A combination of a lower-alkyl 2,6-naphthalenedicarboxylate with ethylene glycol and a combination of a lower-alkyl terephthalate with 1,4-cyclohexanedimethanol are each subjected to a transesterification reaction. A mixture of the obtained reaction products is polycondensed to obtain the objective copolymer. This copolymer is a polyester copolymer represented by the formula (wherein (n) is 100-1000; Ars are a 2,6-naphthalene group and a phenylene group; and Rs are an ethylene group and a 1,4-cyclohexylene group). This copolymer is excellent in heat sealability with an aluminum foil or a film closure, is capable of recycling together with PET and is excellent in oxygen barrier properties and impact resistance.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester copolymer, a method for producing the same, a packaging material and a packaging container. For more details,
The present invention relates to a polyester copolymer having heat resistance and hot water resistance (whitening resistance), a method for producing the same, and a packaging material containing the polyester as a main component, such as a packaging container such as a cup or a bottle, or a packaging material such as a sheet or a film.

[0002]

2. Description of the Related Art Food packaging materials have problems such as hot water resistance (whitening resistance) and transparency, and glass has been mainly used until now, but recently, use of plastics having improved heat resistance has been used. Is progressing. Among them, polyethylene terephthalate (hereinafter abbreviated as PET), which is a type of polyester resin, is widely used as a food packaging material because it has excellent physical and chemical properties and has a recycling system in place. ing. Further, polyethylene-2,6-naphthalate having a naphthalene skeleton (hereinafter referred to as PEN
Is abbreviated as PET) because of its rigidity and planarity.
Has superior mechanical strength (Young's modulus, breaking strength), heat resistance (long-term thermal stability, dimensional stability), chemical properties (chemical resistance, gas barrier property), etc. There is.

To date, various modified PEN resins have been developed in order to modify the properties of this PEN resin. For example, there is a polyester copolymer in which various physical properties such as optical properties and transparency are improved by copolymerizing 1,4-cyclohexanedimethanol as a third component in addition to ethylene glycol as a glycol component. 1-2
No. 01324, JP-A-1-201325, and JP-A-3-122116). Further, there is a polyester copolymer synthesized by adding terephthalic acid as a third component among carboxylic acid components and copolymerizing it (Japanese Patent Publication No. 49-22957).

In addition, among the PET resins, 1,4-cyclohexanedimethanol is copolymerized as a third component, and its cis /
There is a polyethylene terephthalate copolymer thermoforming sheet having improved heat resistance by changing the trans-body ratio (JP-A-5-140278), a PEN resin, and a multilayer film composed of polyethylene terephthalate and a polyethylene terephthalate copolymer (JP-A-SHO). 64
-85732).

[0005]

In many cases, food packaging containers are generally required to have heat resistance and hot water resistance (whitening resistance) sufficient to withstand the sterilization conditions of foods, and Article 7 (1) of the Food Sanitation Act. Of food-specific component standards, manufacturing standards and preservation standards of foods, additives, etc. based on the standard (December 28, 1959, Ministry of Health and Welfare Notification No. 370, last revision: May 31, 1986) P with the manufacturing standard sterilization method in the outline
Water activity (Aw) of 0.94 at H4.0 or more and less than 4.6
Foods of less than sterilization condition (cold spot) at 85 ° C for 30 minutes, water activity (Aw) of 0.9 at pH less than 4.0
Foods of less than 4 are required to be sterilized at 65 ° C. for 10 minutes (cold spot) or sterilized with the same or higher efficacy. Furthermore, the packaging for foods is required to be transparent so that the contents can be confirmed, and is also required to be recyclable against the backdrop of recent environmental problems.

However, the glass used as a packaging material has heat resistance, hot water resistance (whitening resistance), and transparency, but is heavy and has problems such as handling during transportation and risk of breakage. is there.

The packaging material made of PET resin generally deforms under high temperature and high humidity. For example, when used as a food packaging material that is subjected to hot water sterilization treatment, the packaging container is already deformed at 65 ° C. and is not suitable for such applications.
A thermoforming sheet made of polyethylene terephthalate copolymer does not have heat resistance at 87 ° C. Further, when it is kept for several tens of minutes under high temperature and high humidity, it has a drawback that it causes whitening and impairs transparency, and there is a problem that it cannot be used in applications involving heat sterilization.

On the other hand, PEN resin has heat resistance and hot water resistance (whitening resistance) in heat sterilization treatment with hot water at 90 ° C to 100 ° C.
However, it is inferior in heat sealability with the lid material required for packaging materials. That is, the heat sealability with an aluminum closure (a cover material of aluminum foil) having a polyester adhesive layer as the innermost layer is insufficient, and further the adhesive strength decreases with the use conditions. Further, the PEN resin cannot be put in the recycling system of the PET resin because it is whitened by melt-kneading with PET, and there is a problem in terms of recyclability like the multilayer film.

These heat resistance, hot water resistance (whitening resistance),
And, there has never been a material that has both heat sealability and recyclability.

The present invention solves these problems and is transparent and heat-resistant under heat conditions (cold spots) at 85 ° C. for 30 minutes or under sterilization conditions having the same or higher efficacy. It is water-resistant (whitening resistance) and has heat sealability with an aluminum closure (aluminum foil lid) that has a polyester adhesive layer as the innermost layer, and can be recycled with PET as a sheet or packaging material. An object is to provide a possible polyester copolymer, a method for producing the same, a packaging material using the same, and a packaging container.

[0011]

[Means for Solving the Problems] The PET resin is a polyester resin which is used in a large amount and is indispensable for the environment. At present, many measures for a recycling system are considered. Therefore, the present invention pays attention to the fact that even if it is melt-mixed with a PET resin, it can be a recyclable resin as long as it does not affect the transparency, heat resistance and strength.
It was made by newly synthesizing a resin, a polyester copolymer improved from a PEN resin, and found that this resin can solve the above-mentioned problems.
It has heat sealability and recyclability (recyclable with PET) while maintaining heat resistance and hot water resistance (whitening resistance).

The polyester copolymer of the present invention has the following general formula [I].

[0013]

Embedded image

N is 100 to 1000. However, Ar
Is a 2,6-naphthalene group and a phenylene group, and R is an ethylene group and a 1,4-cyclohexylene group.

Each component constituting the polyester copolymer of the present invention contains 30 to 98 mol%, preferably 40 to 90 mol of 2,6-naphthalene group in Ar of the copolymer represented by the general formula [I]. %, Phenylene group is 70 to 2 m
ol%, preferably 60 to 10 mol%. R has an ethylene group of 5 to 90 mol%, preferably 10 to 70 m
ol%, and the 1,4-cyclohexylene group is 95 to 1
It is 0 mol%, preferably 90 to 30 mol%.
The cis / trans ratio of 1,4-cyclohexylene group is 0/100 to 40/60, preferably 0/100 to 30.
The range is / 70.

When the proportion of 2,6-naphthalene groups in Ar in the general formula [I] exceeds 98 mol% and the proportion of phenyl groups is less than 2 mol%, the recyclability and heat sealability are deteriorated, The proportion of 6-naphthalene groups is 30 mol
%, And the proportion of phenyl groups exceeds 70 mol%,
The heat resistance, hot water resistance and whitening resistance are reduced.

If the proportion of 1,4-cyclohexylene groups among R in the general formula [I] exceeds 95 mol% and the ethylene groups are less than 5 mol%, the crystallinity will proceed and the whitening resistance in hot water will be improved. Inferior in sex. When the proportion of 1,4-cyclohexylene group is less than 10 mol% and the ethylene group exceeds 90 mol%, recyclability and heat sealability are deteriorated, and it becomes unsuitable as a packaging container. Similarly, in the 1,4-cyclohexylene group, when the cis / trans isomer ratio exceeds 40 mol%, that is, the trans isomer ratio is 6
If it is less than 0 mol%, the heat resistance is lowered and it becomes unsuitable as a packaging container.

The degree of polymerization n is suitably 100 to 1000, preferably 100 to 400.

As the dicarboxylic acid component of the raw material of the polyester copolymer of the present invention, 2,6-naphthalenedicarboxylic acid or its lower alkyl ester and terephthalic acid or its lower alkyl ester are used. The lower alkyl ester has a carbon number of about 1 to 8, preferably about 1 to 5, in both cases of 2,6-naphthalenedicarboxylic acid and terephthalic acid. Further, these lower alkyl esters may be monoesters as well as diesters. Examples of 2,6-naphthalenedicarboxylic acid lower alkyl ester include 2,6-dimethyl naphthalate, 2,6-diethyl naphthalate, 2,6-dipropyl naphthalate, 2,6-dibutyl naphthalate,
2,6-dipentylnaphthalate, 2,6-dihexylnaphthalate, 2,6-diheptylnaphthalate, 2,
6-dioctyl naphthalate etc. can be mentioned.
Particularly preferred is 2,6-dimethylnaphthalate,
2,6-diethyl naphthalate, 2,6-dipropyl naphthalate, 2,6-dibutyl naphthalate, 2,6-
Dipentyl naphthalate. Examples of terephthalic acid lower alkyl ester include dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, dibutyl terephthalate, dipentyl terephthalate, dihexyl terephthalate, diheptyl terephthalate, dioctyl terephthalate and the like. Particularly preferred are dimethyl terephthalate, diethyl terephthalate, dipropyl terephthalate, dibutyl terephthalate and dipentyl terephthalate.

As glycol components, ethylene glycol and 1,4-cyclohexanedimethanol are used.

The production of the polyester copolymer of the present invention comprises
First, it is advisable to divide the above into a first step of transesterifying the dicarboxylic acid component and the glycol component and a second step of further polycondensing the low polymer of the reaction product obtained in the first step. .

In the transesterification reaction in the first step, 2,6-naphthalenedicarboxylic acid or its lower alkyl ester and terephthalic acid or its lower alkyl ester are used as the dicarboxylic acid component, and ethylene glycol and 1,4- are used as the glycol component. There is cyclohexanedimethanol, but any of them may be combined. That is,
2,6-naphthalenedicarboxylic acid or a lower alkyl ester thereof may be combined with ethylene glycol, 1,4-cyclohexanedimethanol or a mixture of both, and terephthalic acid or a lower alkyl ester thereof may also be mixed with ethylene glycol, 1,4. -Either cyclohexanedimethanol or a mixture of both may be combined. Further, the transesterification reaction of 2,6-naphthalenedicarboxylic acid or a lower alkyl ester thereof and the transesterification reaction of terephthalic acid or a lower alkyl ester thereof may be carried out separately, or one of them may be preceded and the reaction may be completed or after completion of the reaction. The other one may be mixed therein.

One preferred method is to combine 2,6-naphthalenedicarboxylic acid lower alkyl ester and ethylene glycol, and combine terephthalic acid lower alkyl ester with 1,4-cyclohexanedimethanol to cause transesterification of both separately. , A method of obtaining each transesterified low polymer and using this in the second step.

Another preferred method is to first combine terephthalic acid lower alkyl ester and 1,4-cyclohexanedimethanol for transesterification reaction, and then add 2,6-naphthalenedicarboxylic acid lower alkyl ester and ethylene to the reaction product. In this method, glycol is added to continue the transesterification reaction, and the transesterified low polymer thus obtained is subjected to the second step.

The esterification reaction is achieved by reacting 2,6-naphthalenedicarboxylic acid and terephthalic acid with a glycol component in an amount of about 0.8 times or more, preferably 1 to 5 times.

The transesterification method by the transesterification reaction in the first step can be carried out according to a known method.

Any transesterification catalyst may be used as long as it can be used for synthesizing polyester such as polyethylene terephthalate, and examples thereof include Li, Na, K, Mg, Ca, Sr and B.
a, Zn, Cd, Al, Ge, Sn, Pb, Ti, C
Mention may be made of salts of carboxylic acid alcoholates, oxides or acetates of metals selected from the group consisting of r, Mn, Fe, Ni, Sb and Co. These may be used alone or in combination of two or more. The amount of catalyst used is 10 to 1000 mmo with respect to the dicarboxylic acid component.
It is about 1%. The temperature of the transesterification reaction is 150 to
The temperature is in the range of 260 ° C, preferably 220 to 240 ° C. Reaction time is more than the specified reaction rate, usually 80%
Until the above is reached, the lower alcohol produced as a result of the reaction may be distilled out almost completely.

In the second step, the low polymer obtained in the first step is heated under reduced pressure to carry out a polycondensation reaction. In the present invention, before and after the second step is started, specifically, After one step is substantially completed and at a time when the intrinsic viscosity does not exceed 0.2, a polycondensation catalyst such as Sb, Mn, G
The polycondensation reaction is carried out by adding one or more of carboxylic acids, alcoholates, oxides and the like of metals selected from the group consisting of e, Sn, Ti and Sb. The amount of the catalyst used may be about 10 to 1000 mmol% with respect to the dicarboxylic acid component. At this time, if necessary, various additives such as a light-proofing agent, a weather-resistant agent, an antistatic agent, a heat stabilizer, a light-shielding agent and a pigment can be added alone or in combination of several kinds. Further, some of these additives may be compounded in the middle stage or the latter stage of the first step and / or the second step or immediately before the film formation. Addition amount is 1-12 with respect to resin
It is 00 mmol%, preferably 5-1000 mmol%.

After the polycondensation catalyst is added, a second step of obtaining a copolymer having a high degree of polymerization by a deglycol reaction is started.

In the polymerization reaction of the second step, the system is heated and the reaction temperature is gradually raised as the reaction progresses. That is, the reaction starts at 200 to 250 ° C, and finally reaches 270 to 310 ° C.
Heat to a degree. Further, it is preferable that the pressure inside the reaction system is gradually reduced, and that the pressure is finally 10 mmHg or less, preferably 1 mmHg or less at normal pressure at the start of the reaction. Further, the time of the polymerization reaction by this dissolution method is determined by the intrinsic viscosity of the obtained product, but if it is too long, it will be economically disadvantageous and the thermal decomposition reaction will proceed at the same time.
It is carried out for 0.5 to 5 hours, preferably 1 to 4 hours.

Both reaction products obtained by combining 2,6-naphthalenedicarboxylic acid lower alkyl ester and ethylene glycol, combining terephthalic acid lower alkyl ester and 1,4-cyclohexanedimethanol, and transesterifying each of them. In the method of mixing and conducting the polycondensation reaction, in the first step, for example, 2,6
-Dimethyl naphthalate (A) and ethylene glycol (C)
And manganese acetate (for example, 0.02 mol%) are put in a reaction vessel, the temperature is raised to 180 to 240 ° C., and a transesterification reaction is carried out until no distillate is produced to obtain a low polymer (E). Similarly, dimethyl terephthalate (B) and 1,4-
Cyclohexanedimethanol (D) and titanium tetrabutoxy monomer (for example, 0.02 mol%) were placed in a reaction vessel, the temperature was raised to 180 to 240 ° C., and transesterification reaction was performed until no distillate was produced. F) is obtained. If necessary, (A) and (D) and titanium tetrabutoxy monomer (for example, 0.02 mol%) are put in a reaction vessel, heated to 180 to 270 ° C., and transesterified until distillate is no longer produced. Is carried out to obtain a low polymer (G).

Any transesterification catalyst may be used as long as it can be used for the synthesis of polyester such as polyethylene terephthalate, and the known production method described above is used. However, low polymer
When synthesizing (F) and (G), it is not limited to this, and a carboxylic acid, alcoholate or oxide of Ti, or a salt such as acetate is used.

Next, the second step of polycondensation is carried out. The low polymers (E) and (F) obtained in the first step are melt mixed. Optionally low polymer to further control the ingredients
(G) may be added. Trimethyl phosphate (eg 0.04 mol%) and antimony trioxide (eg 0.02 mol%) are added to the molten mixture in this order. For the second step, the known method described above is followed.

Further, terephthalic acid lower alkyl ester
(B) and 1,4-cyclohexanedimethanol (D) are transesterified, and the obtained reaction product is mixed with a lower alkyl ester of 2,6-naphthalenedicarboxylic acid and ethylene glycol to conduct a transesterification reaction again. And then
In the polycondensation reaction of the reaction product thus obtained, in the first step, for example, dimethyl terephthalate (B) and 1,4-cyclohexanedimethanol (D) and titanium tetrabutoxy monomer (for example, 0.02
(mol%) in a reaction vessel, the temperature is raised to 180 to 240 ° C., and a low polymer (F) is obtained by performing a transesterification reaction until no distillate is produced. 2,6-Dimethylnaphthalate (A), ethylene glycol (C), and manganese acetate (for example, 0.02 mol%) were placed in a reaction vessel in the obtained low polymer (F), and the temperature was raised to 180 to 240 ° C. After heating, the ester exchange reaction is carried out until no distillate is produced and low polymer
(H) is obtained. Trimethyl phosphate (eg, 0.04 mol%) and antimony trioxide (eg, 0.02 mol%) are added in this order to the low polymer (H) to carry out polycondensation, and thereafter the polyester copolymer is produced according to the known method described above. To get

In the conventional known production method, when the transesterification product is synthesized, the reactivity between the respective components is different. Therefore, the composition of the obtained low polymer is also biased and its copolymerizability is controlled. Is difficult. The obtained polyester contains most units of the combination of terephthalic acid lower alkyl ester (B) and ethylene glycol (C) having the highest reactivity. This combination is the same as the unit constituting the PET resin, and does not have sufficient heat resistance and hot water resistance (whitening resistance) as compared with other units produced. In the above method, in order to solve this problem, a raw material monomer is preliminarily synthesized with a slow-reacting monomer or a monomer having a highly heat-resistant structure to form a transesterified terephthalic acid lower alkyl ester ( The formation of units consisting of B) and ethylene glycol (C) was avoided. It was confirmed that heat resistance, hot water resistance and the like were further improved by performing polycondensation with the obtained low polymer.

When the polymerization by the melting method is completed, the polymer is usually pressurized with an inert gas, particularly nitrogen gas, discharged, cooled and cut, and then shaped into a desired shape.

The intrinsic viscosity of the polyester copolymer suitable for a food packaging container is about 0.5 to 0.9, preferably 0.55 to 0.7. If it is 0.5 or less, the molded product becomes brittle, and if it is 0.9 or more, the viscosity is high and molding becomes difficult.

Subsequently, the polyester copolymer is subjected to a drying step. This is because when melt extrusion is performed in the presence of water, it undergoes hydrolysis and the molecular weight decreases extremely. In this drying step, the water content of the polyester copolymer after drying is 100 ppm or less, preferably 50 ppm.
It is necessary to do the following. The drying step may be performed by air, under an inert gas flow or under reduced pressure, and the drying conditions such as drying temperature and drying time, the drying method, and the drying equipment may be those used for the thermoplastic polymer, particularly polyester. You can use what you have. For example, since thermal fusion is severe at 120 ° C. or higher, drying may be performed at a temperature lower than 120 ° C. and appropriate selection may be made. As the drying equipment, a vacuum dryer, a rotary dryer, a fluidized dryer, a groove dryer, a stationary dryer and a microwave dryer may be used alone or in combination.

The dried polyester copolymer is put into an extruder, extruded from a T die at an extrusion temperature of 250 to 290 ° C., then cooled and solidified by a cooling drum at 30 to 80 ° C. to obtain an unstretched sheet. It is formed. If it is a twin-screw extruder of the same direction (1 vent or more), it is possible to directly extrude the undried resin. As a cooling method, cooling in two stages,
It may be cooled in water or in a refrigerant (Japanese Patent Publication No. 47-
39929, Japanese Patent Publication No. 47-10394). In addition, the unstretched sheet may be manufactured by a solution casting method (casting method) or a calendar method. The thickness of the sheet is not particularly limited as long as it has a thickness within a range that can be used in ordinary molding techniques. When a product is manufactured by molding into a predetermined shape such as vacuum forming or pressure forming, the product is not limited to this category, and it is particularly desirable that the thickness of the sheet is in the range of 200 to 2000 μm.

The sheet produced as described above is subjected to hot plate forming / vacuum forming (straight forming method or drape forming method), pressure forming / vacuum pressure forming after heating with a far infrared heater or a near infrared heater, or simultaneously with heating. As a result, a mold is formed into a container having a predetermined shape, for example, a cup-shaped container. At this time, the heating temperature of the sheet may vary depending on the composition of the resin, but the surface temperature of the sheet should be 110-110.
It is desirable to keep the temperature range at 150 ° C.

The packaging container can also be manufactured by using the pellets of the polyester copolymer composition of the present invention as a raw material and various general molding methods. Specific examples include molding by injection molding, injection blow molding, or injection biaxial stretch blow molding. In addition, a method of producing a preform which is a preform by injection molding and then heating (stretching) blow-molding to obtain a container, or a method of forming a pipe-shaped intermediate material by extrusion molding and then welding the tip portion to the container It can also be manufactured by a method in which a bottom portion is formed, and then an upper portion is pressed and deformed to form a mouth portion, which is stretch blown.

The container formed from the above sheet is provided with a lid material after filling the contents. The lid material is provided with an aluminum closure (aluminum foil) or a film closure having a polyester adhesive layer as the innermost layer by pressure bonding or heat sealing, or EOE (Easy) mainly composed of metal.
Open End) is provided by double winding. When a lid material having a polyester adhesive layer as the innermost layer is used and the lid is provided by heat sealing, a general polyester adhesive can be used as the sealing agent. For example, PE
T copolymer, PBT copolymer, PCT copolymer,
An example is a polyester-based adhesive made of a PEN copolymer. The heat sealing is generally performed in a temperature range of 140 to 240 ° C. although it varies depending on the heat sealing agent and the like. Aluminum foil, film closure, etc. are used as the lid material.

The packaging material such as the packaging container of the present invention is suitable for food. In particular, foods having a water activity (Aw) of pH 4.0 or more and less than 4.6 are less than 0.94 are treated under the sterilization condition (cold spot) at 85 ° C. for 30 minutes or a method having the same or higher efficacy. It is a packaging material having heat resistance and hot water resistance (whitening resistance) that can withstand this sterilization treatment, and further having transparency and sufficient mechanical strength.

[0044]

EXAMPLES The present invention will be specifically described below with reference to examples, but these do not limit the present invention. The measuring methods of each physical property in the following examples are as follows.

[Measurement Method] Intrinsic Viscosity: The intrinsic viscosity is measured by measuring the resin to be measured with phenol and 1,1,2,2-tetrachloroethane (weight ratio: 6).
0/40) mixed solvent at 100 ° C. for 1 hour with a concentration of 0.
Dissolve it to be 2 to 1.0 g / dl and measure it at 35 ° C. using an Ubbelohde-type capillary viscometer to measure the solution viscosity to 0.
The value was obtained by extrapolating to the value of g / dl.

Infrared absorption spectrum: FT / manufactured by JASCO Corporation
It was measured by IR-5000.

Thermal analysis: The glass transition temperature was determined from the transition point when the sample was heated (10 ° C./min) with a differential scanning calorimeter (DSC).

Composition ratio: Polymer samples were hydrolyzed in basic solution. 2,6-naphthalenedicarboxylic acid / terephthalic acid, 1,2 by gas chromatography
4-Cyclohexanedimethanol / ethylene glycol Each component was quantified to determine the composition ratio.

[Heat resistance and hot water resistance (whitening resistance) test by heat treatment] Water activity (Aw) of 0.9 at pH less than 4.0
F value of foods less than 4 (at the time of lethal heat sterilization) is F (5 ℃ / 6
Water activity (Aw) above pH 4.0 and below 4.6
The F value of foods less than 0.94 (at the time of lethal heat sterilization) is F (8
(° C / 85 ° C), and the relationship between the sterilization temperature of the food itself and time is shown in Table 1 below. From Table 1, the heat resistance of the container is experimentally determined, and a 100 cc container requires heat resistance of 87 ° C. for 20 minutes, and further requires heat resistance of 89 ° C. for 12 minutes.

[0050]

[Table 1]

F (Z / reference temperature) value (heat lethal time):
Heating time (minutes) required to reduce the number of bacteria from N ₀ to N when heated at standard temperature

Z value: temperature change corresponding to 10 times or 1/10 times the D value {applied from the actual measurement value of bacteria to be sterilized}
(Generally 10 ° C, 18 ° F)

D value: The time (minutes) required to reduce the number of survivors to 1/10 when the microorganism is heated at a constant temperature

Standard temperature: Highly acidic food …… 65.0 ° C (149 ° F) Acidic food ………… 85.0 ° C (185 ° F) Low acidic food …… 121.1 ° C (250 ° F)

F ₀ value: F value of reference temperature 121.1 ° C. Z = 10 ° C.

In the following examples and comparative examples, the heat resistance and hot water resistance (whitening resistance) of the cup-shaped molded products produced by molding are such that the water activity (A
w) Heating at 85 ° C., which is a heat sterilization condition of food of less than 0.94, for 30 minutes (cold spot), pH 4.0 less than water activity (Aw), which is heat sterilization condition of food of less than 0.94, for 10 minutes at 65 ° C. As a means of heating (cold spot), use a 100 cc capacity container at 87 ° C for 20 minutes or 89 ° C.
The container was immersed in a constant temperature bath for 12 minutes, and changes in the container volume and whitening due to crystallization were examined and evaluated. The evaluation method is shown below.

[Evaluation Method] i) Heat resistance ◯: Capacity change is less than 2% Δ: Capacity change is 2% or more and less than 3% x: Capacity change is 2% or more ii) Hot water resistance (whitening resistance) (visually ) ○: No whitening △: Some whitening ×: Complete whitening

[Heat Seal Test] In the examples and comparative examples, a cup-shaped molded article produced by molding and an aluminum closure having a polyester adhesive layer as the innermost layer were heated at 190 ° C. for 1 second under a load of 20 kg / cm ² . Heat sealing was performed. Then, the heat seal strength was evaluated to be good (◯) when the heat sealing strength was 180 ° peeling and 1200 to 2200 g / 15 mm, and bad (x) otherwise.

[Recycling Test] In the following Examples and Comparative Examples, PET resin and the polyester copolymer pellets were mixed at a ratio of 1/1, and the screw rotation speed was 20 rpm, the feed section temperature was 260 ° C., and the compression section was a 20φ uniaxial extruder. Temperature 270
C., the temperature of the strand die part was 280.degree. C., and the mixture was melt-kneaded and extruded as a strand. The case where no whitening was visually observed was rated as good (.largecircle.), And the case where whitening occurred was rated as bad (x).

Example 1 30 mol% of 2,6-dimethylnaphthalate (A) and dimethyl terephthalate (B) 7
The dicarboxylic acid raw material consisting of 0 mol% and ethylene glycol (C) 90 mol% and the ratio of the cis form and the trans form are 0 /
100 1,4-cyclohexanedimethanol (D) 10
Glycol raw material consisting of mol%, titanium tetrabutoxy monomer 0.02 mol%, manganese acetate 0.02 mol% were placed in a reaction vessel, and the temperature was 180 to 240 ° C.
The temperature was raised to 0, and a transesterification reaction was carried out until no distillate was produced, and a low polymer was obtained. Next, trimethyl phosphate 0.
While adding 04 mol% and antimony trioxide 0.02 mol% in this order and raising the temperature from 240 ° C to 290 ° C,
The pressure was reduced to 1 torr to make a high vacuum. A polycondensation reaction was carried out while maintaining this temperature and pressure to prepare a polymer having an intrinsic viscosity (IV) of 0.60 and a glass transition temperature (Tg) of 107 ° C. Dicarboxylic acid component ratio A of the obtained polymer
/ B, glycol component ratio C / D is 50/50 and 30/70 respectively from ¹ H-NMR using deuterated trifluoroacetic acid as a measurement solvent, and after alkaline hydrolysis up to the monomer unit, by gas chromatography under normal pressure. It was confirmed that there is. The evaluation results are shown in Table 2.

The undried polyester copolymer flakes produced were co-directional twin-screw extruders (2 vents, L / D = 37,
φ65 screw, 1200mmT die, lip 2.0m
m) was extruded at 290 ° C. and 200 kg / hr, and the cooling device was a touch roll 80 ° C. and a cast roll 8
100 at 0.6 mm sheet at 0 ° C and linear pressure of 30 kg / cm
It was manufactured with a width of 0 mm. Before winding, silicon was coated on both sides or one side with a reverse coater, and was wound with a rewinder through a drying oven for several seconds.

The sheet produced as described above was slit into a width of 560 mm and attached to an unwinder of a simultaneous punching pressure air forming machine, and a 6-row single-row die had a diameter of 80 mm and a depth of 2.
A 7 mm cup-shaped molded product was produced. The molding conditions at this time were a plug assist temperature of 130 ° C. and a pressure of 6 kg / cm.
² , cavity temperature 20 ℃, sheet surface temperature 135
The cycle was 2 to 5 seconds at 1 ° C. 8 for this molded product
For PET resin consisting of OP varnish (overprint varnish) / Al layer having a thickness of 50 μm and polyester adhesive 7 g / m ² as an adhesive layer or Melinex 850 low temperature type seal, which is hot-filled with contents at 7 ° C. Heat sealing was performed at 190 ° C. for 1 second with an aluminum closure at a pressure of 20 kg / cm ² . Heat seal strength is 18
The peeling of the lid material in the 0 degree direction was 2000 g / 15 mm. The void ratio after heat-sealing the cup-shaped molded product and the lid member is 0%. This molded product was transferred to a heat sterilization treatment step, held for 20 minutes by a 87 ° C. hot water shower or a depping system, cooled to 40 ° C. with cold water, and water droplets were blown off with air to produce a product. The heat seal strength with the lid material after heat sterilization is 150 by peeling the lid material in the 180 degree direction.
The strength was 0 g / 15 mm, which was suitable for easy peeling. It was found that the container was not bleached by the heat sterilization treatment and had sufficient heat resistance and hot water resistance (whitening resistance).

The heat resistance, hot water resistance (whitening resistance), heat sealability, and recyclability of this cup-shaped molded product were evaluated, and the evaluation results are shown in Table 2 below. The measurement results of the infrared absorption spectrum of the produced polyester resin are shown in FIG. 1 and Table 4, and the results of thermal analysis are shown in FIG.

Examples 2 to 9 Molar ratio A / of 2,6-dimethylnaphthalate (A) and dimethyl terephthalate (B)
Dicarboxylic acid raw material consisting of B = 30/70, ethylene glycol (C) and 1,4-cyclohexanedimethanol
Molar ratio of (D) C / D = 10/90, 55/45, 94 /
The glycol raw material consisting of 6 and the ratio of the cis- and trans-forms of 1,4-cyclohexanedimethanol are 0/10.
0, 20/80, 40/60 were changed as shown in Table 2, respectively. Other than that, the same operation as in Example 1 was performed to obtain the intended polyester copolymer and its cup-shaped molded article. The evaluation results are shown in Table 2.

[Examples 10 to 18] A dicarboxylic acid raw material having a molar ratio A / B = 65/45 of 2,6-dimethylnaphthalate (A) and dimethyl terephthalate (B), ethylene glycol (C) and 1, 4-Cyclohexanedimethanol (D) molar ratio C / D = 10/90, 55/45, 94
Glycol raw material consisting of / 6 and the ratio of cis isomer to trans isomer of 1,4-cyclohexanedimethanol is 0/10.
0, 20/80, 40/60 were changed as shown in Table 2, respectively. Other than that, the same operation as in Example 1 was performed to obtain the intended polyester copolymer and its cup-shaped molded article. The evaluation results are shown in Table 2.

[Examples 19 to 27] A dicarboxylic acid raw material comprising a molar ratio A / B = 98/2 of 2,6-dimethylnaphthalate (A) and dimethyl terephthalate (B), ethylene glycol (C) and 1, 4-cyclohexanedimethanol
Molar ratio of (D) C / D = 10/90, 55/45, 94 /
The glycol raw material consisting of 6 and the ratio of cis- and trans-forms of 1,4-cyclohexanedimethanol is 0/10.
0, 20/80, 40/60 were changed as shown in Table 2, respectively. Other than that, the same operation as in Example 1 was performed to obtain the intended polyester copolymer and its cup-shaped molded article. The evaluation results are shown in Table 2.

Examples 28 to 33! A dicarboxylic acid raw material composed of a molar ratio A / B = 45/55 of 2,6-dimethylnaphthalate (A) and dimethyl terephthalate (B), ethylene glycol (C) and 1, A glycol raw material composed of a molar ratio C / D of 30-70,75 / 25 of 4-cyclohexanedimethanol (D) and a ratio of cis- and trans-forms of 1,4-cyclohexanedimethanol of 0 / 100,20 /
80, 40/60 and changed as shown in Table 2, respectively.
Other than that, the same operation as in Example 1 was performed to obtain the intended polyester copolymer and its cup-shaped molded article. The evaluation results are shown in Table 2.

[Examples 34 to 39] A dicarboxylic acid raw material comprising a molar ratio of 2,6-dimethylnaphthalate (A) and dimethyl terephthalate (B) A / B = 80/20, ethylene glycol (C) and 1, A glycol raw material composed of a molar ratio C / D of 30-70,75 / 25 of 4-cyclohexanedimethanol (D) and a ratio of cis- and trans-forms of 1,4-cyclohexanedimethanol of 0 / 100,20 /
80, 40/60 and changed as shown in Table 2, respectively.
Other than that, the same operation as in Example 1 was performed to obtain the intended polyester copolymer and its cup-shaped molded article. The evaluation results are shown in Table 2.

Example 40 1952 g of 2,6-dimethylnaphthalate (A) and 15 of dimethyl terephthalate (B)
The dicarboxylic acid raw material consisting of 53.5 g, ethylene glycol (C) 993 g, and the ratio of trans isomer to cis isomer is 80/2.
0 of 1,4-cyclohexanedimethanol (D) 2304
A glycol raw material consisting of g is used. (A) and (C) and manganese acetate 0.02 mol% were put into a reaction vessel, and 180
The temperature was raised to ˜240 ° C., and the transesterification reaction was carried out until no distillate was obtained to obtain a low polymer (E). In the same way
(B) and (D) and titanium tetrabutoxy monomer 0.
02 mol% was put in a reaction vessel, the temperature was raised to 180 to 240 ° C., and a low polymer (F) was obtained by performing a transesterification reaction until no distillate was produced. Next, low polymers (E) and (F)
Were mixed at a molar ratio (E) / (F) = 30/70 to obtain trimethyl phosphate 0.04 mol% and antimony trioxide 0.02 m.
ol% was added in this order and the temperature was raised from 240 ° C. to 300 ° C., and the pressure was reduced to 1 mmHg to obtain high vacuum. The polycondensation reaction is carried out while maintaining this temperature and pressure, and the intrinsic viscosity (IV) is 0.60 and the glass transition temperature (Tg) is 112.
A polymer of ° C was prepared. The dicarboxylic acid component ratio A / B and the glycol component ratio C / D of the obtained polymer were measured by ¹ H-NMR using deuterated trifluoroacetic acid as a measurement solvent, after alkaline hydrolysis to monomer units, and by gas chromatography under normal pressure. From 30/70, 6/94 respectively
Was confirmed. The softening point of the obtained polymer was 90 ° C. Thereafter, a cup-shaped molded product was obtained in the same manner as in Example 1. The heat resistance and hot water resistance (whitening resistance) were evaluated to be good (◯), and whitening did not occur. This and other evaluation results are shown in Table 2.

[Examples 41 and 42] The low polymers (E) and (F) obtained in Example 40 were used in a molar ratio E / F = 50/50, 6
Mixed at 5/35. Thereafter, a polyester copolymer and a cup-shaped molded product thereof were obtained in the same manner as in Example 40. The evaluation results are shown in Table 2.

[Example 43] 732 g of 2,6-dimethylnaphthalate (A) and 135 of dimethyl terephthalate (B)
The dicarboxylic acid raw material consisting of 9.4 g, ethylene glycol (C) 372 g, and the ratio of trans isomer to cis isomer was 80/20.
2016 g of 1,4-cyclohexanedimethanol (D)
The glycol raw material consisting of is used. (B) and (D) and 0.02 mol% of titanium tetrabutoxy monomer were placed in a reaction vessel, the temperature was raised to 180 to 240 ° C., and transesterification reaction was carried out until no distillate was produced. )
I got Into it (A) and (C) and manganese acetate 0.02
Mol% was put in a reaction vessel, the temperature was raised to 180 to 240 ° C., and a transesterification reaction was carried out until no distillate came out to obtain a low polymer (H). Raw material into it Next, trimethyl phosphate 0.04mol%, antimony trioxide 0.02mo
In the order of 1%, the temperature was increased from 240 ° C. to 300 ° C., and the pressure was reduced to 1 mmHg to obtain a high vacuum. The polycondensation reaction is carried out while maintaining this temperature and pressure, the intrinsic viscosity (IV) is 0.60, the glass transition temperature (Tg) is 110 ° C.
Was prepared. The dicarboxylic acid component ratio A / B and the glycol component ratio C / D of the obtained polymer were measured by ¹ H-NMR using deuterated trifluoroacetic acid as a measurement solvent, after alkaline hydrolysis to monomer units, and by gas chromatography under normal pressure. From this, it was confirmed that they were 30/70 and 6/94, respectively. The softening point of the obtained polymer is 8
It was 9 ° C. Thereafter, a cup-shaped molded product was obtained in the same manner as in Example 1. Heat resistance and hot water resistance of the polymer (whitening resistance)
The result of evaluation was good (◯) and whitening did not occur. This and other evaluation results are shown in Table 2.

[Example 44] 1220 g of 2,6-dimethylnaphthalate (A) and 97 of dimethyl terephthalate (B)
1g of dicarboxylic acid raw material and ethylene glycol
A glycol raw material composed of 621 g of (C) and 1440 g of 1,4-cyclohexanedimethanol (D) having a trans-cis ratio of 80/20 is used. Thereafter, a polyester copolymer and a cup-shaped molded product thereof were obtained in the same manner as in Example 43. The heat resistance and hot water resistance (whitening resistance) of the polymer were evaluated to be good (◯), and no whitening occurred. This and other evaluation results are shown in Table 2.

Example 45 1586 g of 2,6-dimethylnaphthalate (A) and 68 of dimethyl terephthalate (B)
0 g of dicarboxylic acid raw material and ethylene glycol
A glycol raw material composed of 807 g of (C) and 1008 g of 1,4-cyclohexanedimethanol (D) having a trans isomer / cis isomer ratio of 80/20 is used. Thereafter, a polyester copolymer and a cup-shaped molded product thereof were obtained in the same manner as in Example 43. The heat resistance and hot water resistance (whitening resistance) were evaluated to be good (◯), and no whitening occurred. This and other evaluation results are shown in Table 2.

Example 46 1952 g of 2,6-dimethylnaphthalate (A) and 15 of dimethyl terephthalate (B)
The dicarboxylic acid raw material consisting of 53.5 g, ethylene glycol (C) 993 g, and the ratio of trans isomer to cis isomer is 80/2.
0 of 1,4-cyclohexanedimethanol (D) 2304
A glycol raw material consisting of g is used. (A) and (C) and manganese acetate 0.02 mol% were put into a reaction vessel, and 180
The temperature was raised to ˜240 ° C., and the transesterification reaction was carried out until no distillate was obtained to obtain a low polymer (E). In the same way
(B) and (D) and titanium tetrabutoxy monomer 0.
02 mol% was put in a reaction vessel, the temperature was raised to 180 to 240 ° C., and a low polymer (F) was obtained by performing a transesterification reaction until no distillate was produced. Similarly, (A) and (D) and 0.02 mol% of titanium tetrabutoxy monomer were put into a reaction vessel, the temperature was raised to 180 to 270 ° C., and a transesterification reaction was carried out until no distillate was produced.
(G) was obtained. Next, the low polymers (E), (F) and (G) are mixed in a molar ratio of
(E) / (F) / (G) = 40/50/10 are mixed, and trimethyl phosphate 0.04 mol% and antimony trioxide 0.02 mol% are added in this order and the temperature is raised to 270 to 310 ° C. did. Thereafter, a polyester copolymer and a cup-shaped molded product thereof were obtained in the same manner as in Example 40. The evaluation results are shown in Table 2.

Reference Examples 1 to 12 Dicarboxylic acid raw material consisting of 2,6-dimethylnaphthalate (A) and dimethyl terephthalate (B), ethylene glycol (C) and 1,4-cyclohexanedimethanol (D) The glycol raw material and the ratio of 1,4-cyclohexanedimethanol cis isomer to trans isomer were changed as shown in Table 2, and otherwise the same operation as in Example 1 was carried out to obtain the polyester copolymer and its cup-shaped product. A molded product was obtained. The evaluation results are shown in Table 2. As a result, it was not possible to satisfy the four characteristics if even one of the components was out of the range.

[Comparative Example 1] A polyethylene terephthalate (PET) sheet and its cup-shaped molded article were prepared in Example 1.
Evaluation was performed in the same manner as the evaluation method described in Table 3 and the results are shown in Table 3.
It was shown to. As a result, both heat resistance and hot water resistance (whitening resistance) were poor.

[Comparative Example 2] A polyethylene naphthalate (PEN) sheet and a cup-shaped molded article thereof were prepared as in Example 1.
Evaluation was performed in the same manner as the evaluation method described in Table 3 and the results are shown in Table 3.
It was shown to. Although heat resistance and hot water resistance (whitening resistance) gave good results, they were inferior in heat sealability and recyclability.

Comparative Example 3 A 0.6 mm-thick two-kind three-layer structure sheet using polyethylene terephthalate and polyarylate and its cup-shaped molded article were evaluated in the same manner as in the evaluation method described in Example 1, and the results were shown. Is shown in Table 3. As a result, heat sealability was good, but deformation and whitening occurred.

Example 47 Direct Blow Molding The same operation as in Example 1 was carried out to obtain a polyester copolymer having an IV of 0.60, which was then further polymerized by solid phase polymerization to give a high molecular weight I. A polyester copolymer having a .V. = 1.02 was obtained.

The undried polyester copolymer thus produced was dried in a vacuum dryer at 80 ° C. for 10 hours in order to reduce the water content of the resin to 50 ppm or less.
0-280 ° C, barrel middle temperature 270-280 ° C, barrel rear temperature 270-280 ° C, nozzle temperature 280-3
00 ° C, mold chiller temperature 10-30 ° C, blow pressure 6-
Direct blow molding was performed under the conditions of 10 kg / cm ² and a cycle time of 7 sec to form a transparent small bottle having a capacity of 300 ml.

The molded product was hot-filled with the contents at 87 ° C. and capped with a metal screw cap.

This molded product was transferred to the heat sterilization treatment step, and
After holding for 20 minutes in a 7 ° C hot water shower or a depping system, it was cooled to 40 ° C with cold water, and water droplets were blown off with air to produce a product. As a result, it was found that there was no whitening of the container due to the heat sterilization treatment, and that it had sufficient heat resistance and hot water resistance (whitening resistance).

The heat resistance, hot water resistance (whitening resistance), and recyclability of this bottle-shaped molded product were evaluated, and the evaluation results are shown in Table 5.

Example 48 Injection Molding The same operation as in Example 1 was carried out to obtain a polyester copolymer having an IV of 0.60.

The undried polyester copolymer produced was heated at 80 ° C. for 10 minutes in order to reduce the water content of the resin to 50 ppm or less.
hr dry, then barrel front temperature 270-280
℃, barrel middle temperature 270 to 280 ℃, barrel rear temperature 270 to 280 ℃, hot runner nozzle temperature 28
0 to 300 ° C, filling pressure 100 kg / cm ² , rotation speed 5
0 rpm, filling time 3 sec, holding pressure 35 kg / cm
² , mold chiller temperature 10 ~ 30 ℃, cycle time 1
Injection molding (injection molding) was performed under the condition of 5 to 20 seconds to mold a cup-shaped molded product (15 g).

The molded product was hot-filled with the contents at 87 ° C., and the temperature was adjusted to 190 ° C. with an aluminum closure for PET resin, which was composed of an OP varnish / Al layer having a thickness of 50 μm and a polyester adhesive 7 g / m ² as an adhesive layer. Pressure 20kg / c
Heat sealing was performed at m ² for 1 second. Heat seal strength is 1800g / 15m by peeling the lid material in the 180 degree direction.
It was m. The void ratio after heat-sealing the cup-shaped molded product and the lid member is 0%.

This molded product was transferred to the heat sterilization treatment step,
After holding for 20 minutes with a 7 ° C hot water shower or a depping method, the product was cooled to 40 ° C with cold water, and water droplets were blown off with air to obtain a product. The heat seal strength with the lid material after heat sterilization is 1485 g when peeling the lid material in the 180 degree direction.
The strength was / 15 mm, which was suitable for easy peeling. It was found that the container was not bleached by the heat sterilization treatment and had sufficient heat resistance and hot water resistance (whitening resistance).

The heat resistance, hot water resistance (whitening resistance), heat sealability, and recyclability of this cup-shaped molded article were evaluated, and the evaluation results are shown in Table 5.

Example 49 Injection Biaxial Stretch Blow Molding (Hot Parison Method) The same operation as in Example 1 was carried out to obtain a polyester copolymer having an IV of 0.60.

The undried polyester copolymer thus produced was dried in a vacuum dryer at 80 ° C. for 10 hours in order to reduce the water content of the resin to 50 ppm or less.
Mold parison by injection molding at 0-280 ° C, barrel middle temperature 270-280 ° C, barrel rear temperature 270-280 ° C, hot runner nozzle temperature 280-300 ° C, and cool it to 70-90 ° C as it is. Move to temperature control step, heat up to 130-150 ° C in temperature control step and move to blow step, perform biaxial stretch blow molding with blow pressure 25 kg / cm ² , mold chiller temperature 10-30 ° C, cycle time 15 sec. It was possible to mold a transparent bottle with a capacity of 500 ml.

This molded product was hot-filled with the contents at 87 ° C. and capped with a metal screw cap.

This molded product was transferred to the heat sterilization treatment step,
After holding for 20 minutes in a 7 ° C hot water shower or a depping system, it was cooled to 40 ° C with cold water, and water droplets were blown off with air to produce a product. As a result, it was found that there was no whitening of the container due to the heat sterilization treatment, and that it had sufficient heat resistance and hot water resistance (whitening resistance).

The heat resistance, hot water resistance (whitening resistance), and recyclability of this bottle-shaped molded product were evaluated, and the evaluation results are shown in Table 5.

Example 50 Injection Biaxial Stretch Blow Molding (Cold Parison Method) The same operation as in Example 1 was carried out to obtain a polyester copolymer having an IV of 0.60.

The undried polyester copolymer produced was
Use a vacuum dryer to reduce the water content of the resin to 50 ppm or less.
Dry at 80 ° C for 10 hr, then barrel front temperature 27
0-280 ℃, barrel middle temperature 270-280 ℃, barre
Nozzle of hot runner, rear temperature 270-280 ℃
Part temperature 280 to 300 ° C, filling pressure 100 kg / c
m ², Rotation speed 50 rpm, filling time 4 sec, holding pressure
35 kg / cm², Mold chiller temperature 10 ~ 30 ℃,
Pre-molded by injection molding with an icle time of 23 to 28 seconds
The foam (16 pieces) was molded.

The obtained preform was heated to 130 to 150 ° C. by a near infrared heater in a biaxial stretching blow molding machine in a separate process, and was blown using a stretching rod and compressed air of 40 kg / cm ² or more. Biaxially stretch blow molding was carried out.

At this time, the chiller temperature of the blow mold is 10 to 3
The temperature was 0 ° C., and as a result, a transparent stretched bottle having a capacity of 500 ml could be molded.

The molded product was hot-filled with the contents at 87 ° C. and capped with a metal screw cap.

This molded product was transferred to the heat sterilization treatment step,
After holding for 20 minutes in a 7 ° C hot water shower or a depping system, it was cooled to 40 ° C with cold water, and water droplets were blown off with air to produce a product. As a result, it was found that there was no whitening of the container due to the heat sterilization treatment, and that it had sufficient heat resistance and hot water resistance (whitening resistance).

The heat resistance, hot water resistance (whitening resistance), and recyclability of this bottle-shaped molded product were evaluated, and the evaluation results are shown in Table 5.

[0101]

[Table 2]

Comparison of conventional products

[Table 3]

[0103]

[Table 4]

[0104]

[Table 5]

[0105]

The container obtained by thermoforming the above-mentioned copolymer sheet has a potency of 87 ° C. for 20 minutes, 85 ° C. for 30 minutes, or equivalent or higher as a packaging container for food use requiring heat sterilization. It can be used without being deformed, whitened, or reduced in volume even if it is treated by the method. Also,
Aluminum foil, heat seal with film closure, PE
It can be recycled with T and has an excellent oxygen gas barrier and impact resistance.

[Brief description of drawings]

FIG. 1 is a diagram showing an infrared absorption spectrum of a polyester copolymer composition obtained in Example 1.

FIG. 2 is a diagram showing a DSC curve of the polyester copolymer obtained in Example 1.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kayo Hasegawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Nihon Kokan Co., Ltd. (72) Inventor Junichi Kitagawa 1-2-1, Marunouchi, Chiyoda-ku, Tokyo Date Inside the Steel Pipe Co., Ltd. (72) Inventor Yoichiro Inoue 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Joint printing Co., Ltd. (72) Inventor Eiichi Kai 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Joint printing stock In-house (72) Inventor Shin Sekine 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Within Kyodo Printing Co., Ltd. (72) Inventor Yuzo Fukawa 4-12-12 Koishikawa, Bunkyo-ku, Tokyo Within Kyodo Printing ( 72) Inventor Takashi Shirane 4-14-12 Koishikawa, Bunkyo-ku, Tokyo Co-printing Co., Ltd. (72) Inventor Hamahiro 4-chome Koishikawa, Bunkyo-ku, Tokyo 14th-12th Kyodo Printing Co., Ltd.

Claims (7)

[Claims] 1. A polyester copolymer represented by the general formula [I]: n is 100 to 1000. However, Ar is 2,6-
Naphthalene group and phenylene group, R is ethylene group and 1,4
A cyclohexylene group. 2. Ar is a 2,6-naphthalene group 30 to 98.
mol%, phenylene group 70 to 2 mol%, R is ethylene group 5 to 90 mol%, 1,4-cyclohexylene group 95 to 10 mol%, and cis / trans ratio of 1,4-cyclohexylene group. Is 0: 100-4
The polyester copolymer according to claim 1, which is in the range of 0:60. 3. A combination of 2,6-naphthalenedicarboxylic acid lower alkyl ester and ethylene glycol, and terephthalic acid lower alkyl ester and 1,4-cyclohexanedimethanol are each subjected to transesterification reaction to obtain both products. The method for producing a polyester copolymer according to claim 1, wherein the reaction products are mixed and a polycondensation reaction is performed. 4. A lower alkyl ester of terephthalic acid and 1,4-cyclohexanedimethanol are transesterified, and the obtained reaction product is mixed with a lower alkyl ester of 2,6-naphthalenedicarboxylic acid and ethylene glycol. The method for producing a polyester copolymer according to claim 1, wherein the transesterification reaction is carried out again, and the reaction product thus obtained is subjected to a polycondensation reaction. 5. A packaging material containing the polyester copolymer according to claim 1 or 2 as a main component. 6. A packaging container obtained by vacuum forming or pressure forming the packaging material according to claim 5. 7. A packaging container obtained by molding the polyester copolymer according to claim 2 by any one of direct blow molding, injection molding, injection blow molding, and injection biaxial stretch blow molding.