JP2006082871A - Flat container made of polyester resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a polyester resin flat container obtained by blow molding, which is excellent in physical properties, such as heat resistance, by specifying a flat container and imparting properties to it, thereby improving mechanical strength, heat resistance, etc., peculiar to the flat container. <P>SOLUTION: The polyester resin flat container is obtained by blow-molding a polyester resin. In the polyester resin flat container, a flat ratio, or a ratio between a long diameter and a short diameter, is not smaller than 1.3, a ratio between the maximum thickness and minimum thickness of the barrel 2 of the container is not larger than 1.6, and a difference between the maximum extendible part and the minimum extendible part of the barrel 2 of the container in terms of tensile test at 95°C is not more than 150%. Further, the degree of crystallinity of the barrel 2 of the container is not less than 30%, and a difference between the maximum extendible part and the minimum extendible part of the barrel 2 of the container in terms of an amount of TMA no-load variation is not more than 500 μm at 75°C and 100°C. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flat container made of a polyester resin. More specifically, the cross section is elliptical or rectangular, the container body has a uniform wall thickness, has high heat resistance, and does not deform at high temperatures. It relates to the flat container which is characterized.

  Polyester containers such as PET bottles have been in great demand since they were approved as containers for food and drink due to their excellent mechanical strength, transparency, high gas shielding properties, and resource reusability. In particular, it has recently been used by consumers as a small portable container for beverages, and the heat and pressure resistance has been remarkably improved by the development of a two-stage blow molding method, etc., and it can also be used for high temperature beverages and beverages that require high temperature sterilization. It can be used to meet the strong demands of consumers for portable high temperature beverages for winter.

  And, because of the ease of holding beverage bottles and the aesthetics of complex shapes, recent consumers prefer flat bottles with a rectangular cross section, and bottles with a circular cross section are difficult to grip due to slipperiness. It tends to be shunned by the lack of aesthetic feeling due to the simple shape of the circle.

Polyester resin flat containers with a flat shape with high added value and a very high demand, are molded by blowing a preformed bottomed parison into a flat cross section mold (blow molding) However, when forming into a flat shape, the wall thickness of the container wall tends to be non-uniform, and as a countermeasure, for example, in the shorter diameter direction than the portion extending in the longer diameter direction of the flat shape Heat the bottomed cold parison before blow molding so that the stretched part is hotter, or increase the thickness of the stretched part in the major axis direction and increase the thickness of the stretched part in the minor axis direction. A flat bottle is manufactured by a bottomed cold parison blow molding method or the like in which the formed bottomed parison is used to rotate the bottomed parison in the axial direction and radiatively heat from the surroundings (see Patent Document 1).
In addition, several methods for manufacturing a flat container by blow molding have been disclosed, but generally, since the cross section is flat, the expansion and expansion in the cavity of the bottomed parison is not uniform. It is difficult to obtain a uniform thickness, and there is a possibility of a reservoir due to insufficient stretching on the short diameter side, making it difficult to produce a flat container having a uniform thickness on the body of the container. If the thickness is not uniform, the mechanical strength and heat resistance of the container will decrease due to the thin wall, and the container will not be able to withstand the external pressure load due to the internal pressure load due to the beverage in the container at high temperature and the internal contraction when the temperature drops. There is a risk of deformation.

  On the other hand, in the flat container by blow molding, from the viewpoint different from the improvement intention of the blow molding method, the specific mechanical strength and heat resistance of the flat container can be improved by specifying and imparting characteristics to the flat container. However, there has been almost no improvement proposal to prevent the possibility of deformation of the container by enduring the internal pressure load due to the beverage in the container at high temperature and the external pressure load due to the internal contraction when the temperature drops, and simply the flatness (the maximum length of the trunk) That is, a polyolefin-type injection blow-molded flat container in which the thickness is specified (refer to Patent Document 2).

JP 2000-127230 A (Claims and paragraphs 0005 to 0008) JP-A-11-170344 (Claims 1 to 3 of Claims)

  In light of the prior art described in paragraphs 0002 to 0005, the present inventors are very favored by consumers as plastic containers for beverages, and in polyester resin flat containers obtained by blow molding, where demand is particularly increasing. Inventing a flat container with excellent mechanical properties and heat resistance by specifying the flat container and imparting characteristics to improve the mechanical strength and heat resistance unique to the flat container. This is a problem to be solved.

  The present inventors aim to solve the above-mentioned problems in the flat container by blow molding, and in order to clearly materialize the flat container excellent in mechanical strength and heat resistance, the specification in the flat container Considering in detail the provision of properties and characteristics, and considering the methods to embody them from various viewpoints such as physical properties and container structure, in the process, the major axis and minor axis of the trunk section of the container representing flatness Ratio (flat ratio) and the thickness ratio of the container body, which is an index indicating the uniformity of the thickness of the entire body of the container. In connection with the amount of thermal no-load change in the body or the crystallinity of the body of the container, it can be found that they are deeply related to the mechanical strength and heat resistance of the flat container. As a result, by specifying those correlations as numerical values Te, which resulted in the creation of the present invention.

  Specifically, the flattening ratio and the thickness ratio are experimentally selected and specified as a numerical range, and the extension of the container body at high temperature is specified as the maximum stretched part of the container body. The difference in elongation in the 95 ° C tensile test at the minimum stretched part is adopted to specify the amount of thermal no-load change in the container body at high temperature, and the container body in the range of 75 ° C and 100 ° C. A flat container with excellent mechanical strength, heat resistance, etc. is clearly realized by selecting the difference in TMA no-load change between the maximum stretched part and the minimum stretched part and correlating the relationship between them. It became possible to materialize.

The present invention is composed of the following invention unit groups, and the inventions [1] to [3] are used as basic inventions, and the inventions below that embody the basic inventions or embodiments. is there.
[1] A flat container in which a polyester resin is blow-molded, wherein the ratio of the major axis to the minor axis is 1.3 or more, and the maximum thickness part and the minimum thickness part of the barrel part of the container A polyester resin flat container having a ratio of 1.6 or less and a difference in elongation in a 95 ° C. tensile test between a maximum stretched part and a minimum stretched part of a body part of the container being 150% or less.
[2] A flat container in which a polyester resin is blow-molded, wherein the ratio of the major axis to the minor axis is 1.3 or more, and the maximum thickness part and the minimum thickness part of the trunk part of the container The ratio is 1.6 or less, the crystallinity of the body of the container is 30% or more, and the difference in TMA no-load change between the maximum stretched part and the minimum stretched part of the container body is 75 ° C and 100 ° C. A flat polyester resin container having a thickness of 500 μm or less.
[3] A flat container in which a polyester resin is blow-molded, wherein the ratio of the major axis to the minor axis is 1.3 or more, and the maximum thickness part and the minimum thickness part of the trunk part of the container The ratio is 1.6 or less, the difference in elongation in the 95 ° C. tensile test between the maximum stretched portion and the minimum stretched portion of the container body is 150% or less, and the crystallinity of the container body is 30% or more. A polyester resin flat container, wherein the difference in TMA no-load change between the maximum stretched portion and the minimum stretched portion of the body portion of the container is 500 μm or less at 75 ° C. and 100 ° C.
[4] The polyester resin flat container according to any one of [1] to [3], wherein the cross-sectional shape of the body of the flat container is rectangular or elliptical.
[5] The polyester resin flat container according to any one of [1] to [4], wherein the flat container is a biaxially stretched container formed by a two-stage blow molding method.
[6] The polyester resin flat container according to any one of [1] to [5], wherein the polyester resin is polyethylene terephthalate.
[7] The polyester resin flat container according to any one of [1] to [6], wherein the flat container has a multilayer structure of a polyester resin layer and a functional thermoplastic resin layer.

The flat container in the present invention is excellent in mechanical strength and heat resistance, the shape of the container is stable even at high temperatures, and cannot withstand the external pressure load due to internal pressure load due to the beverage in the container at high temperature and internal contraction when the temperature drops. There is no risk of deformation of the container.
Therefore, the flat container is particularly excellent as a high temperature beverage container or a high temperature sterilized beverage container, and is also suitable for general foods and medicines.

Hereinafter, embodiments of the invention of the present invention group described above will be described in detail with reference to the drawings.
(1) Flat container As shown in FIGS. 3 to 4, the flat container of the present invention is preferably a container having a flat cross section such as a rectangle or an ellipse, except for the mouth. In FIGS. 3-4, the external view and sectional drawing, such as a front view, a side view, and an arrow view, in a flat container are illustrated.
The flat shape makes it easy to hold a beverage bottle by grasping a consumer's fingers, does not slip even when the container surface is wet during use, and has aesthetics due to its complicated shape.

(2) A flat container in which a polyester resin is blow-molded The specified flat container of the present invention is manufactured by blow-molding a bottomed parison that is preformed from a polyester resin.
In addition, the inventors of the present application, prior to the creation of the present invention, for producing a flat container having a uniform thickness, excellent mechanical strength and heat resistance, and stable container shape even at high temperatures. Since the invention of the flat container blow molding method has been devised and filed earlier (Japanese Patent Application No. 2003-314851), the flat wall of the present invention can be formed by uniformly forming the wall thickness of the container. In order to manufacture the flat container, preferably, the blow molding method according to the prior invention can be used.

  Specifically, a preformed parison having a uniform cross-sectional wall thickness and a substantially circular cross section is subjected to primary blow molding, and a short diameter of a mold for secondary blow molding (short diameter of a flat container). A mold having a cavity with a cross-sectional shape of a flat container of a molded product, and this bottomed parison is used for secondary blow molding. The bottomed stretched parison is pressed in a flat shape in the minor axis direction of the cavity and clamped in the mold to perform secondary blow molding. As a result, the bottomed stretched parison has a longer cross section on the longer diameter side than the minor diameter side of the cavity, and the bottomed parison is accommodated. The thickness of the flat container on the short diameter side and the long diameter side is uniform or sufficiently uniform. As a result, the biaxially stretched two-stage blow is performed, whereby the bottomed parison is sufficiently stretched and crystallized, and the heat resistance and pressure resistance of the flat container are remarkably improved. The following actions are also involved.

The primary blow of the bottomed parison uses a mold for stabilizing the shape after the blow, but may be performed by a free blow that does not use a mold in terms of economy.
The primary blow can have a transverse stretching ratio of 3 to 5 times and a longitudinal stretching ratio of 2 to 4 times, resulting in high crystal orientation and uniform stretching. Further, the draw ratio on the short diameter side (the short diameter of the container / the center diameter of the preform) can be suppressed to about 2.5 times. The mold temperature condition of the primary blow is about 150 ° C. in the PET, and the free blow is cooled by air cooling. Blow molding is preferably a biaxially stretched two-stage blow method in order to improve the physical properties of the molded product.
In general, since the mouth of the container is not stretched, it is separately heated and crystallized to improve strength and heat resistance.
The specified flat container of the present invention is preferably produced by blow molding a bottomed parison preformed from a polyester resin by the method as described in the above paragraphs 0013 to 0015. Various characteristics such as the flatness ratio and the wall thickness ratio described below are appropriately given depending on the setting of the molding conditions and the like and in each example described later.

(3) Flatness ratio A ratio of a major axis and a minor axis (both outer diameters) of the trunk section of the container representing flatness, and represents a flatness ratio that is an indicator of the flatness of the container. Specifically, in the container having flatness shown in FIGS. 3 to 4, the major axis (6) in the horizontal section (BB, DD) of the body (2,102) of the container (1,101). , 106) and the minor axis (7, 107).
In the present invention, the flatness ratio is the thickness ratio of the container body, the extensibility of the container body at a high temperature, the amount of change in thermal no-load of the container body at a high temperature, or the container body. The flatness ratio is 1.3 or more based on experimental data (posted in Table 1 below) because it is deeply related to the mechanical strength and heat resistance of the flat container in relation to the degree of crystallinity of the part. This numerical specification also provides ease of holding a beverage bottle by grasping a consumer's finger and aesthetics by a complicated shape.

(4) Thickness ratio of the container body The thickness ratio of the container body is an index indicating the uniformity of the thickness of the entire body of the container. Preferably, it is shown as the thickness ratio of the maximum thickness portion and the minimum thickness portion of the cross section of the container body excluding the container neck and the ground contact portion.
Like the flatness ratio, the wall thickness ratio is related to extensibility in the container body at high temperature, thermal no-load change in the container body at high temperature, or crystallinity of the container body. Since it is deeply related to the mechanical strength and heat resistance of the flat container, it must be 1.6 or less from the experimental data (posted in Table 1 below).

(5) Difference in elongation at high temperature The difference in elongation at high temperature is deeply related to the mechanical strength and heat resistance of the flat container. Specifically, the maximum stretched part (column part) of the body of the container And the difference in elongation in the 95 ° C. tensile test at the minimum stretched portion (panel central portion). It is calculated by the experimental method described later in paragraph 0025 and needs to be 150% or less from the experimental data (posted in Table 1 below).
If the difference in elongation between the maximum stretched part and the minimum stretched part is 150% or less, the shape is stable even when the contents of the container are filled at a high temperature of about 95 ° C. Will not be deformed and distorted.

(6) Crystallinity This is an index (unit:%) indicating the crystallinity of the body of the flat container, and is related to the mechanical strength and heat resistance of the flat container as well as the flatness ratio. It is necessary to be 30% or more based on (posted in Table 1).
The degree of crystallinity is a numerical value essential for improving the heat resistance of the container, and is calculated by an experimental calculation formula described later in paragraph 0024.

(7) Difference in unloaded change amount The difference in unloaded change amount of the flat container is deeply related to the mechanical strength and heat resistance of the flat container as well as the difference in elongation at high temperature. The difference between the TMA (thermomechanical analysis) no-load change amount of the maximum stretched portion and the minimum stretched portion in the body portion of the container in the range of ° C and 100 ° C is adopted. It is calculated by the experimental method described later in paragraph 0026 and needs to be 500 μm or less from the experimental data (posted in Table 1 described later).
The difference in the amount of TMA no-load change particularly shows the evaluation of heat resistance, and if it is 500 μm or less, it is stable in shape even when the containing contents are filled at a high temperature of about 95 ° C. Thus, the shape is not deformed and distorted.
Since flat containers have different stretch ratios or secondary processing amounts for the maximum stretched part and the minimum stretched part in the body part of the container, the heat resistance of the column part and the panel part is different. Although the bulging heat resistance tends to be poor, the flat container of the present invention that satisfies this rule has excellent heat resistance because the difference in orientation between the maximum stretched portion and the minimum stretched portion is smaller than that of the conventional method. Therefore, the panel part does not protrude even if the contents are filled at a high temperature.

(8) Polyester resin material The resin material of the flat container is a polyester resin, and examples include polylactic acid. However, in consideration of mechanical strength and heat resistance, ordinary polyethylene terephthalate (PET) is mainly used. Polyethylene terephthalate is a crystalline resin whose main repeating unit is ethylene terephthalate, and preferably 90 mol% or more of the acid component is terephthalic acid and 90 mol% or more of the glycol component is ethylene glycol. Examples of other acid components of this PET include isophthalic acid and naphthalene dicarboxylic acid, and examples of other glycol components include diethylene glycol, 1,4-butanediol, cyclohexanedimethanol and propylene glycol.
The resin constituting the container may be blended with a functional resin such as oxygen absorbing property or oxygen shielding property. In addition, various additives such as a normal colorant, an ultraviolet absorber, an antioxidant, and an antibacterial agent may be appropriately blended depending on the application.

(9) Multilayer material The present invention is also directed to a polyester resin flat container characterized in that the flat container has a multilayer structure of a polyester resin layer and a functional thermoplastic resin layer. In addition, a laminated bottomed parison which is a multilayer material can be used. For example, when laminated with polyamide or Eval, oxygen shielding properties are improved. In addition, an oxygen absorption layer may be provided in the intermediate layer to improve oxygen absorption. The oxidizable organic component used in the oxygen absorbing layer is preferably a polymer derived from polyene. As such a polyene, a resin containing a unit derived from a polyene having 4 to 20 carbon atoms, a linear or cyclic conjugated or non-conjugated polyene is preferably used.

  In the following, the present invention will be described in more detail with reference to the drawings by comparing the comparative examples, but the following examples and comparative examples illustrate preferred embodiments of the present invention. This is to more clearly explain the present invention and to prove the rationality of the constituent elements of the present invention.

[Measurement method]
1. ) Cut out from the test piece body portion of the measurement the flat container crystallinity, of the test piece by a density gradient tube method Density ρ Request (g / cm ^3). The crystallinity is calculated by the following formula.
Crystallinity (%) = {ρc (ρ−ρa) / ρ (ρc−ρa)} × 100
ρc: Crystal density (1.455 g / cm ³ )
ρa: amorphous density (1.335 g / cm ³ )

2. ) Measurement of 95 ° C. tensile test elongation difference As shown in FIG. 3, it is longer (higher) than the maximum extension part (column part) 9 and the minimum extension part (panel center part) 10 on the same height of the body part of the flat container. A) A 5 × 40 mm strip test piece cut in the direction is subjected to a tensile test in a thermostatic chamber at 95 ° C. The difference between the maximum elongation at the two locations is defined as the difference in the tensile elongation at 95 ° C.
The distance between chucks is measured at 10 mm, the crosshead speed is measured at 10 mm / min, the distance between chucks is L ₀ , and the distance that the sample is extended is ΔL, and displayed as elongation (%) = (ΔL / L ₀ ) × 100. did.
The apparatus used was Tensilon Universal Testing Machine UCT-500 manufactured by Orientec Co., Ltd.
In addition, the graph figure showing the example of the measurement result of 95 degreeC tensile test elongation amount difference is illustrated in FIG. In FIG. 1, the maximum difference in elongation between the maximum stretched portion and the minimum stretched portion is 389-333 = 56%.

3. ) Measurement of difference in TMA no-load change amount As shown in FIG. 3, vertical (higher) than the maximum extension part (column part) 9 and the minimum extension part (panel center part) 10 on the same height of the body part of the flat container 5) A strip-shaped test piece of 5 × 40 mm cut in the direction is measured by TMA (thermomechanical analysis). The difference between the two amounts of change is defined as the difference in the TMA no-load change amount.
In addition, as a measuring method of the difference in TMA no-load change amount, the stress applied to the test piece is 0, the distance between chucks is 20 mm, and the temperature is increased from room temperature to 100 ° C. at a heating rate of 5 ° C./min. The change amount is digitized by calculating the change amount up to 100 ° C. starting from 75 ° C. near the glass transition temperature. As the apparatus, DMS-6100 manufactured by Seiko Instruments Inc. was used.
In addition, the graph figure showing the example of the measurement result of the difference of TMA no-load change amount is illustrated in FIG. From FIG. 2, the difference in the amount of change between the maximum stretched portion and the minimum stretched portion when the temperature reaches 100 ° C. with 75 ° C. as a reference is 42 − (− 68) = 110 μm. (Equivalent to Example-1)

4). ) Method for evaluating heat resistance A flat container was filled with hot water at 87 ° C., sealed and further subjected to a 75 ° C. hot water shower for 5 minutes, and the presence or absence of deformation of the container was visually evaluated. (○: No deformation ×: With deformation)

[Example-1]
Using commercially available polyethylene terephthalate (PET), a bottomed parison with an outer diameter of 22 mm, a thickness of 3.4 mm, and a height of 80 mm is preformed, and heated air is blown by free blow, and primary stretching is performed to an outer diameter of 90 mm. Blowed.
The primary blown bottomed parison was shrunk and fixed in an oven at 600 ° C. for 8 seconds to obtain a shrunk bottomed parison having an outer diameter of 60 mm.
The contracted bottom parison was crushed in the minor axis direction and stored in a rectangular cavity (cross section: minor axis 50 m, major axis 66 mm) of the secondary blow mold (set at 140 ° C.).
In a shrunk bottomed parison deformed by crushing, air at 20 ° C. and 3 MPa was fed and subjected to secondary blow molding to form a flat container having a rectangular cross section of 1.3.
The crystallinity of the body of this flat container, the thickness ratio of the maximum thickness part and the minimum thickness part of the cross section of the container, the amount of elongation in the 95 ° C tensile test at the maximum extension part and the minimum extension part of the container body part Table 1 shows the measurement results of the difference and the difference in TMA no-load change in the range of 75 ° C. and 100 ° C. in the maximum stretched portion and the minimum stretched portion of the body of the container.
As shown in Table 1, the thickness ratio in the circumferential direction of the body of the container is small as compared with each comparative example, and the difference in physical properties between the maximum stretched portion and the minimum stretched portion of the body of the container is small. Also, the heat resistance was good and the mechanical strength was sufficient.

[Example-2]
Example except that the primary blow molding was not a free blow, but a primary blow mold was used, and a cavity with an elliptical cross section (cross section: minor axis 47 mm, major axis 70 mm) was used as the secondary blow mold. 1. A flat container having an elliptical flatness ratio of 1.5 was formed.

[Example-3]
Example-1 except that a primary blow mold was used for primary blow molding instead of free blow, and a cavity with a rectangular cross section (cross section: minor axis 40 mm, major axis 80 mm) was used as the secondary blow mold. A flat container having a flatness ratio of 2.0 having a rectangular cross section was formed.

[Example-4]
Example-1 except that a primary blow mold was used for primary blow molding instead of free blow, and a cavity with a rectangular cross section (cross section: minor axis 36 mm, major axis 90 mm) was used as the secondary blow mold. A flat container having a flatness ratio of 2.5 and a rectangular cross section was formed.
Crystallinity of the body of the flat container formed in Examples 2 to 4, the thickness ratio of the maximum thickness part and the minimum thickness part of the cross section of the container, 95 in the maximum extension part and the minimum extension part of the container body part Table 1 shows the measurement results of the difference in elongation in the tensile test at 0 ° C. and the difference in TMA no-load change in the range of 75 ° C. and 100 ° C. in the maximum stretched portion and the minimum stretched portion of the body of the container.
In Examples 2 to 4, as shown in Table 1, the thickness ratio in the circumferential direction of the body of the container is small as compared with the comparative examples, and the maximum stretched portion and the minimum stretched portion of the body of the container Thus, the difference in physical properties was small, and therefore the heat resistance was good and the mechanical strength was sufficient.

[Comparative Example-1]
Using the same preformed bottomed parison as used in Example 1, the preformed bottomed parison was stretched with a primary blow mold, and the contracted bottomed parison was not crushed in the minor axis direction. In the mold, and using the same secondary blow mold as used in Example-1, blow molding is performed under the same blowing conditions, and the cross section is rectangular with a flatness ratio of 1.3. A flat container was formed.

[Comparative Example-2]
Using the same preformed bottomed parison as used in Example 1, the preformed bottomed parison was stretched with a primary blow mold, and the contracted bottomed parison was not crushed in the minor axis direction. In the mold, and using the same secondary blow mold as used in Example-3, blow molding is performed under the same blow conditions, and the cross section is rectangular with a flatness ratio of 2.0. A flat container was formed.
Crystallinity of the barrel portion of the flat container molded in Comparative Examples 1 and 2, the thickness ratio of the maximum thickness portion and the minimum thickness portion of the cross section of the container, 95 in the maximum extension portion and the minimum extension portion of the container barrel portion Table 1 shows the measurement results of the difference in elongation in the tensile test at 0 ° C. and the difference in TMA no-load change in the range of 75 ° C. and 100 ° C. in the maximum stretched portion and the minimum stretched portion of the body of the container.
In each comparative example, as shown in Table 1, the circumferential thickness ratio of the container body and the difference in physical properties between the maximum stretched portion and the minimum stretched portion of the container body are large. The mechanical strength was inferior.

[Consideration of results of Examples and Comparative Examples]
By comparing each example and each comparative example, in the present invention, if it is a flat container that satisfies the structural requirements such as the flat ratio, thickness ratio, 95 ° C tensile test elongation difference and TMA difference, the heat resistance is improved. It is clear that it is excellent.
In each example, the difference in elongation at high temperature between the maximum stretched portion and the minimum stretched portion is smaller than that in each comparative example, and the difference in TMA no-load change is also smaller than that in each comparative example. Excellent and stable in shape even when the contents are filled at a high temperature, and the shape is not deformed and distorted unlike a conventional flat container.
Therefore, the significance and rationality in the requirements of each component of the present invention are demonstrated.

It is a graph which shows the example of the measurement result of the difference in 95 degreeC tensile test elongation amount. It is a graph which shows the example of the measurement result of the difference of TMA no load change amount. It is the external view and sectional drawing which show the rectangular polyester resin flat container of this invention, and a measurement sample collection location. It is the external view and sectional drawing which show the elliptical-type polyester resin flat container of this invention.

Explanation of symbols

1,101 Polyester resin flat container 2,102 Container trunk 3,103 Container bottom 4,108 Container neck 5,105 Container shoulder 6,106 Container trunk major axis 7,107 Container trunk minor axis 8,104 Container mouth 9 Maximum stretched part (column) measurement sample collection position 10 Minimum stretched part (panel center) measurement sample collection position

Claims (7)

A flat container in which a polyester resin is blow-molded, a ratio of a major axis to a minor axis is 1.3 or more, and a thickness ratio between a maximum thickness part and a minimum thickness part of the trunk of the container is 1 A polyester resin flat container, wherein the difference in elongation in a 95 ° C. tensile test between the maximum stretched portion and the minimum stretched portion of the body portion of the container is 150% or less. A flat container in which a polyester resin is blow-molded, a ratio of a major axis to a minor axis is 1.3 or more, and a thickness ratio of a maximum thickness part to a minimum thickness part of a body part of the container is 1 .6 or less, the crystallinity of the body of the container is 30% or more, and the difference in TMA no-load change between the maximum stretched part and the minimum stretched part of the container body is 500 μm or less at 75 ° C. and 100 ° C. Polyester resin flat container characterized by being. A flat container in which a polyester resin is blow-molded, a ratio of a major axis to a minor axis is 1.3 or more, and a thickness ratio of a maximum thickness part to a minimum thickness part of a body part of the container is 1 .6 or less, the difference in elongation in the 95 ° C. tensile test between the maximum stretched part and the minimum stretched part of the container body is 150% or less, and the crystallinity of the container body is 30% or more, A polyester resin flat container characterized in that the difference in TMA no-load change between the maximum stretched portion and the minimum stretched portion of the body portion of the container is 500 μm or less at 75 ° C. and 100 ° C. The polyester resin flat container according to any one of claims 1 to 3, wherein a cross-sectional shape of a body portion of the flat container is a rectangle or an ellipse. The flat resin container according to any one of claims 1 to 4, wherein the flat container is a biaxially stretched container formed by a two-stage blow molding method. The polyester resin flat container according to any one of claims 1 to 5, wherein the polyester resin is polyethylene terephthalate. The flat container according to any one of claims 1 to 6, wherein the flat container has a multilayer structure of a polyester resin layer and a functional thermoplastic resin layer.

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