JP2006297873A - Heat-resisting polyester drawing molded container and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester drawing molded container having outstanding heat resistance which can resist a high temperature of 100°C or higher. <P>SOLUTION: The heat-resisting polyester drawing molded container comprises at least a polyester resin, wherein the time required for the calorific value of the isothermal crystallization at 130°C of the polyester resin to reach the maximum is 4.5-12 minutes, with respect to the measured values of the dynamic viscoelasticity at least in the body portion, the maximum tanδ value is 0.3 or lower, and a temperature for the maximum tanδ is 115°C or lower. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a polyester stretch-molded container and a method for producing the same, and more specifically, a polyester stretch-molded container having heat resistance that can withstand high temperatures of 100 ° C. or higher, and a single-stage blow-molding method for such a polyester stretch-molded container. The present invention relates to a manufacturing method that can be formed by the above method.

Stretch-molded containers of thermoplastic polyester resins such as polyethylene terephthalate have excellent transparency and surface gloss, as well as impact resistance, rigidity, and gas barrier properties required for containers such as bottles and cups. It is used as a container for various beverages and foods.
For example, in the manufacture of a wide-mouthed bottling product, it is necessary to heat sterilize or sterilize the contents after hot filling or filling the contents in order to enhance the shelf life of the contents. However, stretch-molded containers made of polyester resin have the disadvantage of poor heat resistance and cause heat deformation and shrinkage deformation in volume when the contents are hot filled. (Heat setting) is being performed.

The heat resistance imparted to the stretch-molded container made of polyester resin by heat setting can withstand temperatures of about 90 ° C. such as hot filling, but heat sterilization or the like such as retort sterilization performed after filling the contents. Sterilization is performed for about 20 to 50 minutes in a high-temperature atmosphere of 100 ° C. or higher. As a result, it is difficult to obtain heat resistance sufficient to withstand heat sterilization only by heat setting after molding.
In addition, as a method for improving the heat resistance of a stretched polyester container, it has been proposed to use a polyester resin comprising 70 to 5% by weight of polyethylene terephthalate and 30 to 95% by weight of polybutylene terephthalate. The heat resistance obtained even when using the polymerized polyester resin was only about 90 ° C. (Patent Document 1).

  For this reason, a two-stage blow molding method has been proposed in which heat resistance at a high temperature exceeding 100 ° C. is achieved by subjecting the first-stage blow-molded product to heat shrinkage and heat fixation and then final blow molding. In addition, according to the two-stage blow molding method, it is possible to provide a polyester stretch-molded container having excellent heat resistance that can withstand heat sterilization in a high temperature region as described above (Patent Document 2). .

Japanese Patent Laid-Open No. 5-178338 JP 2001-150522 A

That is, in the two-stage blow molding method, the temperature of the heat set performed after the first-stage and second-stage blow molding is high. Since the processing rate in molding is suppressed, it is possible to reduce the residual strain. As a result, even when using ordinary polyethylene terephthalate without using a special copolyester, it is 100 ° C. or higher. It is possible to form a polyester stretch-molded container having excellent heat resistance that can withstand the high temperatures.
However, since the two-stage blow molding method has more molding steps than the one-stage blow molding method, there is a problem that the equipment is expensive and the energy cost is high, and the heat set temperature is high. There is a problem in that the mold releasability is deteriorated and the appearance of the molded product is poor due to adhesion of the oligomer mold, and a polyester stretch-molded container having heat resistance that can withstand high heat of 100 ° C. or higher is provided by a one-stage blow molding method. It is hoped that.

Accordingly, an object of the present invention is to provide a polyester stretch-molded container having excellent heat resistance that can withstand high temperatures of 100 ° C. or higher.
Another object of the present invention is to provide a production method capable of forming a stretched polyester container having excellent heat resistance by a one-stage blow molding method.

According to the present invention, in a stretch-molded container having a layer made of at least a polyester resin, the time for which the calorific value of isothermal crystallization of the polyester resin at 130 ° C. reaches a maximum value is 4.5 to 12 minutes, There is provided a heat-resistant polyester stretch-molded container having a measured dynamic viscoelasticity of tan δ maximum value of 0.3 or less and a tan δ maximum temperature of 115 ° C. or less.
In the polyester stretch-molded container of the present invention,
1. At least 0.5% shrinkage attainment temperature in the TMA measurement of the body part is 130 ° C. or more and the shrinkage rate at 200 ° C. is 3% or less,
2. The polyester resin is a blend or copolymer of two or more polyester resins;
3. Two or more types of polyester resins are polyethylene terephthalate and cyclohexanedimethanol-containing polyester resins,
4. Two or more kinds of polyester resins are polyethylene terephthalate and polybutylene terephthalate,
Is preferred.

  According to the present invention, a preform made of a polyester resin in which the amount of heat generated by isothermal crystallization at 130 ° C. reaches a maximum value is 4.5 to 12 minutes, a preform temperature of 110 to 120 ° C. and 120 to 180 ° C. There is provided a method for producing a heat-resistant polyester stretched container, which is characterized by stretch blow molding under the condition of a mold heat set temperature of 0 ° C.

In the present invention, the heat generation amount of the isothermal crystallization of the polyester resin at 130 ° C. reaches a maximum value of 4.5 to 12 minutes, so that excellent heat resistance that can withstand a high temperature of 100 ° C. or more is obtained. A stretching container having the same can be obtained.
In particular, when a blend of polyethylene terephthalate and cyclohexanedimethanol-containing polyester resin is used as the polyester resin, at least 0.5% shrinkage attainment temperature in the TMA measurement of the barrel is 130 ° C. or higher and the shrinkage rate at 200 ° C. is 3 %, It can be used suitably for contents that require heat sterilization such as retort sterilization.
In the present invention, heat resistance of 100 ° C. or more, which can be realized only by the conventional two-stage blow molding method, can be realized by the one-stage blow molding method, which is excellent in productivity, cost, and the like.

In the heat-resistant polyester stretch-molded container of the present invention, in a stretch-molded container having at least a layer made of a polyester resin, the time for which the calorific value of isothermal crystallization of the polyester resin at 130 ° C. reaches a maximum value is 4.5 to 12. Minute is an important feature.
In order to maintain heat resistance that can withstand high temperatures of 100 ° C. or higher in a stretched polyester molded container, it has a high degree of crystallinity that can maintain a high elastic modulus when exposed to such high temperatures, and is resistant to molding distortion. It is necessary for the residual strain to be low so that the shrinkage deformation caused by it can be suppressed.
In order to obtain a polyester stretch-molded container by a single-stage blow molding method, the present inventors need to achieve rapid crystallization by a mold heat set in order to obtain a high degree of crystallinity. It is necessary to have a fast crystallization rate in the set temperature region (150 to 180 ° C.), while on the other hand, in order to reduce the residual strain due to molding, resin properties that can enable stretch molding with low stress at high temperature, In other words, it was necessary that there was no stretching inhibition due to crystallization, and for this reason, it was found that the polyester resin used must have a moderate crystallization rate in the stretching temperature range (110 to 120 ° C.).

  From such a point of view, in the polyester stretch-molded container of the present invention, the polyester resin layer has an appropriate crystallization rate of 4.5 to 12 minutes in which the heat generation amount of isothermal crystallization at 130 ° C. reaches the maximum value. Thus, it is possible to provide the above-described characteristics in both temperature ranges in a well-balanced manner and to have heat resistance that can withstand a high temperature of 100 ° C. or higher.

In the polyester stretch-molded container of the present invention, it is a desirable and important feature that at least the dynamic viscoelasticity measured value of the trunk part is tan δ maximum value is 0.3 or less and the tan δ maximum temperature is 115 ° C. or less. That is, since tan δ is a value obtained by dividing the loss elastic modulus E ″ by the storage elastic modulus E ′, that the tan δ maximum value is 0.3 or less indicates that the ratio of the amorphous part contributing to the loss component is This means that it is less than the crystal part that contributes to the storage component, and means that heat fixation by crystallization is sufficiently performed. The tan δ maximum temperature of 115 ° C. or lower is a state where the glass transition temperature of the amorphous part is close to the glass transition temperature in the unconstrained state, and the tension and restraint of the polymer chain due to the residual strain This means that the heat resistance is high enough to withstand a high temperature of 100 ° C. or higher.
Further, it is desirable that at least the 0.5% shrinkage attainment temperature in the TMA measurement of the body part is 130 ° C. or more and the shrinkage rate at 200 ° C. is 3% or less. That is, by having such characteristics, it becomes possible to exhibit ultra-high heat resistance to a high temperature of 100 ° C. or higher.

In the present invention, the time for the calorific value of isothermal crystallization at 130 ° C. to reach the maximum value is 4.5 to 12 minutes, the measured dynamic viscoelasticity of at least the trunk is tan δ maximum value is 0.3 or less, and tan δ The fact that the maximum temperature is 115 ° C. or less has a critical significance in terms of heat resistance is also apparent from the results of Examples described later.
That is, the polyester stretch-molded container in which the time for the calorific value of isothermal crystallization at 130 ° C. to reach the maximum value is within the above range is the amount of change in the internal volume even when subjected to retort sterilization (120 ° C.) after filling the contents. Is suppressed to 3% or less. It can also be seen that the tan δ maximum value is 0.3 or less and the tan δ maximum temperature is 115 ° C. or less (Examples 1 to 3).
In particular, in Examples 1 and 2, the 0.5% shrinkage reaching temperature in TMA measurement is 210 ° C. or more, which greatly exceeds 130 ° C., and the shrinkage rate at 200 ° C. is 3% or less, even for a high temperature of 130 ° C. or more. It turns out that it has the outstanding heat resistance.
On the other hand, in any case where the heat generation amount of isothermal crystallization at 130 ° C. reaches the maximum value in less than 4.5 minutes or more than 12 minutes, the polyester stretch-molded container shrinks and deforms due to retort sterilization. It is clear that the heat resistance is poor (Comparative Examples 1 to 5). In addition, even when the heat generation amount of isothermal crystallization at 130 ° C. reaches a maximum value of 4.5 to 12 minutes, the tan δ maximum value is 0 when high-temperature stretching and high-temperature mold heat setting are not performed. 3 (Comparative Example 6), or the tan δ maximum temperature is higher than 115 ° C. (Comparative Example 7), indicating that the heat resistance is poor.

(Polyester resin)
As described above, the polyester stretch-molded container of the present invention can be molded by ordinary single-stage blow molding without using a two-stage blow molding method. What is important at this time is the heat setting temperature and the stretching temperature, and it is necessary to perform stretch blow molding and heat setting at a higher temperature than when forming a stretch molded container made of ordinary polyethylene terephthalate. It is necessary to select a resin that can handle stretch blow molding and heat setting at a high temperature.
That is, as described above, the polyester resin to be used must have a fast crystallization rate in the heat set temperature range (150 to 180 ° C.) and a moderate crystallization rate in the stretching temperature range (110 to 120 ° C.). For this reason, in the present invention, it is important to use a polyester resin in which the time during which the calorific value of isothermal crystallization at 130 ° C. reaches the maximum value is in the range of 4.5 to 12 minutes.

Any polyester resin may be used as long as it has such a crystallization rate.
In the present invention, it is desirable to use a blend or copolymer of two or more polyester resins as the most suitable adjustment of the crystallization speed of the polyester resin.
The blend or copolymer of two or more kinds of polyester resins is not limited to this, but particularly compared to polyethylene terephthalate such as cyclohexanedimethanol-containing polyester resin, polybutylene terephthalate, polytrimethylene terephthalate. A combination of a polyester resin having a high crystallization rate and polyethylene terephthalate is particularly preferable.

As the cyclohexanedimethanol-containing polyester resin, those having crystallinity are preferable. When cyclohexanedimethanol-modified polyethylene terephthalate is used, it becomes amorphous when it contains about 30 mol% of cyclohexanedimethanol as an alcohol component. Therefore, the range excluding this region, that is, 0.1 to 20 mol% of cyclohexanedimethanol. Or cyclohexanedimethanol-modified polyethylene terephthalate containing 40 to 99.9 mol%.
The blend ratio (weight ratio) of the cyclohexanedimethanol-containing polyester resin and polyethylene terephthalate depends on the content of cyclohexanedimethanol in the cyclohexanedimethanol-containing polyester resin used, but the cyclohexanedimethanol-containing polyester resin is 0.1%. It is preferable that it is blended in an amount of from 30 to 30% by weight, particularly from 1 to 15% by weight. By blending in the above range, residual strain due to stretch molding at high temperature is low, and heat setting at high temperature. It is possible to obtain both excellent crystallinity and excellent heat resistance.
When a cyclohexanedimethanol-containing polyester resin is used, it is particularly desirable to use a resin containing cyclohexanedimethanol in the range of 0.1 to 20% by weight in order to ensure transparency.

In the case of a combination of polybutylene terephthalate and polyethylene terephthalate, it is necessary that the polybutylene terephthalate is blended in an amount of 10% by weight or less, particularly 0.1 to 5% by weight.
When the combination of polytrimethylene terephthalate and polyethylene terephthalate is used, it is necessary that the polytrimethylene terephthalate is blended in an amount of less than 20% by weight, particularly 0.1 to 10% by weight.
In the case of using polybutylene terephthalate and polytrimethylene terephthalate, if the blending amount is larger than the above range, the crystallization speed becomes excessive, and it is not preferable because stretch molding at high temperature becomes difficult.

The polyethylene terephthalate used in the present invention is preferably homopolyethylene terephthalate in terms of heat resistance, but may be a copolyester containing a small amount of ester units other than ethylene terephthalate units.
Dibasic acids other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; succinic acid, adipic acid, sebacic acid, dodecanedioic acid, etc. Or a combination of two or more thereof.
Examples of the diol component other than ethylene glycol include one or more of propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexylene glycol, cyclohexane dimethanol, and bisphenol A ethylene oxide adduct. It is done.

Similarly, the polybutylene terephthalate and polytrimethylene terephthalate may be not only a homopolymer but also a copolymer in which a small amount of the above-described copolymerization component for polyethylene terephthalate is introduced.
The polyester resin used should have a molecular weight sufficient to form at least a film, and its intrinsic viscosity (IV) is generally 30 ° C. in a mixed solvent of 50:50 weight ratio of phenol and tetrachloroethane. Those measured in temperature are preferably in the range of 0.72 to 0.90 dL / g, particularly 0.73 to 0.88 dL / g.

In order to adjust the crystallization speed of the polyester resin, in addition to using a blend or copolymer of two or more kinds of polyester resins as described above, a crystal nucleating agent or a low molecular component exhibiting a plasticizing effect may be added, It can be prepared by controlling the water content, adjusting the amount of water during molding, adjusting the catalyst type and amount, and the like.
As the crystal nucleating agent, those used as a polymer nucleating agent can be used, and any of inorganic crystal nucleating agents such as talc and organic crystal nucleating agents such as organic acid amides and organic carboxylic acid metal salts can be used. can do. The crystal nucleating agent is generally preferably blended in an amount of 0.01 to 0.3 parts by weight per 100 parts by weight of the polyester resin, although it depends on the type of polyester resin used.
The low molecular weight component exhibiting a plasticizing effect includes glycerin plasticizers such as glycerin monoacetomonolaurate, polyvalent carboxylic acid ester plasticizers such as dimethyl phthalate, and polyalkylene glycols such as polyethylene glycol and polypropylene glycol. A plasticizer etc. can be illustrated. Generally, the plasticizer is preferably blended in an amount of 0.01 to 0.3 parts by weight per 100 parts by weight of the polyester resin, although it depends on the type of polyester resin used.
The crystal nucleating agent and the plasticizer may each be used alone, or both may be used in combination to adjust the crystallization rate.

(Other resins)
The stretch-molded container of the present invention may be a single layer or a stretched multilayer preform having a layer made of a thermoplastic resin other than the polyester resin as long as it has a layer made of the polyester resin. In this case, it is particularly preferable that the polyester resin constitutes the inner and outer layers.
As the thermoplastic resin other than the polyester resin, any resin can be used as long as it is a resin that can be stretch blow molded and thermally crystallized, and is not limited thereto, but is not limited thereto, ethylene-vinyl alcohol copolymer, cyclic olefin polymer, etc. Olefin-based resins and polyamide resins such as xylylene group-containing polyamides. In addition, oxygen-absorbing gas barrier resin compositions containing diene compounds and transition metal catalysts in polyamides containing xylylene groups, recycled polyesters (PCR (resin that recycles used bottles), SCRs (generated in production plants) Resin) or a mixture thereof) can also be used. These recycled polyester resins preferably have an intrinsic viscosity (IV) measured by the method described above in the range of 0.65 to 0.75 dL / g.

Moreover, in order to adhere | attach an inner layer or an outer layer, and an intermediate | middle layer, adhesive resin can also be interposed. As the adhesive resin, an acid-modified olefin resin or polyester resin obtained by graft polymerization of maleic acid or the like, or an amorphous polyester resin or polyamide resin can be used.
The polyester resin or thermoplastic resin other than the polyester resin used in the present invention has various additives such as a colorant and an ultraviolet absorber as long as the quality of the biaxially stretched container as the final molded product is not impaired. , Mold release agents, lubricants, nucleating agents and the like can be blended.

(Molding of stretch-molded container)
In order to mold the polyester stretch-molded container of the present invention, a preform is first formed using the above-described polyester resin by a conventionally known method such as injection molding or compression molding.
In the present invention, in the stretch blow molding, it is important to stretch the molded preform by heating to a stretching temperature of 110 to 120 ° C., preferably 115 to 120 ° C., and the stretching temperature is in the above range. By being in such a high temperature region, it becomes possible to reduce residual strain. Here, the heating temperature of the preform, that is, the stretching temperature is the outer surface temperature of the preform immediately before the stretch blow molding, and can be measured by a radiation thermometer, a thermal image measuring instrument, or the like.
In order to heat the preform uniformly and at high speed to the above temperature, it is preferable to heat the preform from the inside and outside of the preform by means of hot air, an infrared heater, high frequency induction heating or the like before and after the stretching blow.

The preform is supplied into a publicly known stretch blow molding machine, set in a mold, stretched and stretched in the axial direction by pushing a stretch rod, and stretched and molded in the circumferential direction by blowing blow air. In order to efficiently perform stretch molding at a high temperature in the method of the present invention, it is preferable to blow hot air at 100 to 150 ° C. as blow air.
In general, the mold temperature is preferably from room temperature to 190 ° C. However, as described later, when heat setting is performed by the one mold method, it is important to set the mold temperature to 120 to 180 ° C. In the present invention, since stretch blow molding is performed at a temperature higher than usual, there is a risk of oligomer precipitation due to high temperature stretching. Therefore, in order to prevent this, it is preferable to use a surface-treated mold. Further, in order to increase the releasability and suppress deformation after molding, it is preferable to cool the molded product by circulating room temperature or cooling air in the blow bottle as cooling air at the time of mold release.
The stretch ratio in the biaxially stretched container is suitably 1.5 to 25 times in terms of area ratio. Among these, the axial stretch ratio is 1.2 to 6 times, and the circumferential stretch ratio is 1.2 to 4.5. It is preferable to double.

In the present invention, as described above, it is important to heat-set at a temperature of 120 to 180 ° C., preferably 150 to 180 ° C. after the stretch molding. The heat setting can be performed by means known per se, and can also be performed by a one-mold method performed in a blow mold, or a two-mold performed in a heat mold separate from the blow mold. It can also be done by law.
From the viewpoint of handling properties, it is desirable to cool with cold air when taking out from the mold after heat setting.
Further, heat resistance can be improved by heating and crystallizing before blow molding in a portion that is not stretched due to a molding method such as a container mouth.

1. Materials Polyethylene terephthalate resin (RT543CTHP: Nihon Unipet Co., Ltd.) as the main material, polybutylene terephthalate resin (Julanex 500FP: Polyplastics Co., Ltd.), isophthalic acid-modified polybutylene terephthalate resin (polyester) DURANEX 600LP: Polyplastics Co., Ltd., crystalline cyclohexanedimethanol-containing polyethylene terephthalate resin (RD353C: Nippon Unipet Co., Ltd.), amorphous cyclohexanedimethanol-containing polyethylene terephthalate resin (S2008: SK Chemical), or Using a polyethylene naphthalate-polyethylene terephthalate copolymer (TN8756: Teijin Chemicals Ltd.), the main material and each blended polyester species were dry blended in a pellet state at a predetermined mixing ratio and subjected to various moldings. In addition, each resin was dried before mixing.

2. Molding of stretch blow bottle The dry blend of the above resin pellets at a specified ratio is supplied to the hopper of an injection molding machine (NN75JS: Niigata Steel Co., Ltd.), barrel setting temperature is 280 ° C, cycle time 30 Injection molding was performed in seconds to form a preform for a bottle having a diameter of 28 mm. After that, the body of the preform, whose mouth has been whitened by heating in advance, is heated to a predetermined surface temperature by a heated iron core from the inside with an infrared heater from the outside, and then stretched by biaxial stretching and blowing. The stretched blow bottle 1 shown in FIG. 1 having a capacity of 500 ml with a magnification of 3 times in length, 3 times in width, and 9 times in area was formed. The mold temperature was set to room temperature (25 ° C.), 150 ° C. and 180 ° C. In addition, cooling air was introduced into the container at the time of mold release.

3. Measurement (1) Time for the calorific value of isothermal crystallization at 130 ° C to reach the maximum value
About the sample (10 mg) cut out from the panel part of the bottle trunk part, it measured using the differential scanning calorimeter (DSC7: product made from PERKIN ELMER). The measurement temperature profile is as follows.
1. From room temperature to 290 ° C, heated at 300 ° C / minute, held at 2.290 ° C for 5 minutes, melted to 3.130 ° C, quenched at 300 ° C / minute, held at 4.130 ° C for 30 minutes, in order of isothermal crystallization Scan and above 4. The time (minutes) required for the crystallization heat generation amount to reach the maximum value was measured.

(2) Tan δ in dynamic viscoelasticity measurement
A test piece having a size of 10 mm × 30 mm was cut from the panel portion of the bottle body so that the long side direction was the bottle height direction, and the measurement was performed using a viscoelastic spectrometer (EXSTAR6000DMS: Seiko Instruments Inc.). The measurement conditions are shown below.
Measurement mode: Tensile sine wave mode Distance between test specimens: 20 mm
Frequency: 1Hz
Minimum tension: 100mN
Temperature rising profile: Temperature rising from 25 ° C. to 210 ° C. at 2 ° C./min. From the obtained tan δ curve, the tan δ maximum value and the tan δ maximum temperature were derived.

(3) 0.5% shrinkage attainment temperature in TMA measurement and shrinkage rate at 200 ° C. A test piece 10 mm × 30 mm large is cut out from the panel part of the bottle body so that the long side direction is the bottle height direction, and viscoelasticity spectroscopy is performed. Measurement was performed using a meter (EXSTAR6000DMS: Seiko Instruments Inc.). The measurement conditions are shown below.
Measurement mode: F control mode Test piece initial gauge distance: 20mm
Stress profile: Unweighted Temperature rise profile: Temperature rise from 25 ° C. to 210 ° C. at 2 ° C./min A shrinkage rate curve was calculated from the obtained shrinkage amount curve using the following equation.
S (shrinkage rate:%) = X / L × 100
X: Shrinkage at each temperature (mm) L: Distance between initial gauge points (mm) = 20 mm
The amount of shrinkage at the start of measurement was set to 0, and from the calculated shrinkage rate curve, the temperature at which the shrinkage rate of 0.5% was reached (0.5% shrinkage arrival temperature) and the shrinkage rate when the temperature reached 200 ° C. ( The shrinkage at 200 ° C. was derived.

(4) Evaluation of retort suitability After filling the molded stretch blow bottle with tap water and sealing with an aluminum cap, heat treatment is performed at 120 ° C for 30 minutes in an autoclave, and the internal volume changes before and after the treatment. Those with a rate of 3% or less were considered appropriate.

Example 1
Polyethylene terephthalate resin (RT543CTHP: Nihon Unipet Co., Ltd.) is used as the main material, and polybutylene terephthalate resin (500FP: Polyplastics Co., Ltd.) is used as the blend polyester species. = 95: 5 was dry blended and supplied to an injection molding machine hopper, and a preform for a bottle with a diameter of 28 mm was injection molded under the conditions of a set temperature of 280 ° C. and a cycle time of 30 seconds.
The preform mouth was crystallized in advance, and then biaxially stretched and blow molded to produce a stretched blow bottle having a capacity of 500 ml and a barrel central part thickness of 0.35 mm. At this time, the heating temperature of the preform, that is, the stretching temperature was set to 115 ° C., and the heat setting temperature of the blow mold was set to 180 ° C.
Each site | part of this bottle was cut out and each said measurement and evaluation of retort aptitude were performed.

(Example 2)
Crystalline cyclohexanedimethanol-containing polyethylene terephthalate resin (RD353C: Nippon Unipet Co., Ltd.) is used as the blend polyester seed, and dry blended at a weight ratio of main material: blend polyester seed = 90: 10 and injection molding machine. Except having supplied to the hopper, the stretch blow bottle was created similarly to Example 1, and said each measurement and evaluation of retort aptitude were performed.

(Example 3)
A stretch blow bottle was prepared in the same manner as in Example 2 except that the mold heat set temperature was set to 150 ° C., and the above measurements and evaluation of retort suitability were performed.

(Comparative Example 1)
A stretch blow bottle was prepared in the same manner as in Example 1 except that only polyethylene terephthalate resin (RT543CTHP: Nippon Unipet Co., Ltd.) was used as a material, and the above measurements and retort suitability were evaluated.

(Comparative Example 2)
Stretch blow bottle in the same manner as in Example 1 except that it is dry blended at a weight ratio of main material: blend polyester type = 90: 10 and supplied to the injection molding machine hopper, and the heating temperature of the preform is set to 105 ° C. Was prepared, and each of the above measurements and evaluation of retort suitability were performed.
With this material composition, when the preform heating temperature was set to 110 ° C. or higher, molding became impossible due to crystallization.

(Comparative Example 3)
As the blended polyester species, an isophthalic acid-modified polybutylene terephthalate resin (600LP: Polyplastics Co., Ltd.) was used, and a stretch blow bottle was prepared in the same manner as in Example 2 except that the heating temperature of the preform was set to 105 ° C. Each of the above measurements and retort suitability were evaluated.
With this material composition, when the preform heating temperature was set to 110 ° C. or higher, molding became impossible due to crystallization.

(Comparative Example 4)
A stretch blow bottle was prepared in the same manner as in Example 2 except that amorphous cyclohexanedimethanol-containing polyethylene terephthalate resin (S2008: SK Chemical) was used as the blend polyester species, and the above measurements and evaluation of retort suitability were performed. It was.

(Comparative Example 5)
A stretched blow bottle was prepared in the same manner as in Example 2 except that a polyethylene naphthalate-polyethylene terephthalate copolymer (TN8756: Teijin Chemicals Ltd.) was used as the blend polyester species, and the above measurements and evaluation of retort suitability were performed. Went.

(Comparative Example 6)
A stretch blow bottle was prepared in the same manner as in Example 3 except that the mold heat set temperature was set to 25 ° C., and the above measurements and evaluation of retort suitability were performed.

(Comparative Example 7)
A stretch blow bottle was prepared in the same manner as in Example 2 except that the heating temperature of the preform was set to 105 ° C., and the above measurements and evaluation of retort suitability were performed.

  Table 1 shows the results of the above measurements.

The side view of the biaxial stretching blow bottle created in the Example.

Claims (6)

  In a stretch-molded container having a layer composed of at least a polyester resin, the time required for the calorific value of isothermal crystallization of the polyester resin at 130 ° C. to reach the maximum value is 4.5 to 12 minutes, and at least measuring the dynamic viscoelasticity of the trunk A heat-resistant polyester stretch-molded container having a tan δ maximum value of 0.3 or less and a tan δ maximum temperature of 115 ° C. or less.   The heat-resistant polyester stretch-molded container according to claim 1, wherein at least 0.5% shrinkage attainment temperature in the TMA measurement of the body part is 130 ° C or more and the shrinkage rate at 200 ° C is 3% or less.   The heat-resistant polyester stretch-molded container according to claim 1 or 2, wherein the polyester resin is a blend or copolymer of two or more polyester resins.   The heat-resistant polyester stretch-molded container according to claim 3, wherein the two or more kinds of polyester resins are polyethylene terephthalate and cyclohexanedimethanol-containing polyester resin.   The heat-resistant polyester stretch-molded container according to claim 3, wherein the two or more kinds of polyester resins are polyethylene terephthalate and polybutylene terephthalate.   A preform made of a polyester resin in which the amount of heat generated by isothermal crystallization at 130 ° C. reaches a maximum value of 4.5 to 12 minutes is drawn at a stretching temperature of 110 to 120 ° C. and a mold heat set temperature of 120 to 180 ° C. A process for producing a heat-resistant polyester stretched container, wherein the stretch blow molding is performed under the following conditions.

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