JP2018027822A - container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an accident of removal of a bottom part or the like even when a pressure difference is generated by a difference of sea level altitudes between an inside and outside of a tightly plugged container.SOLUTION: In a vertical cross section structure of a container formed of a polyester resin composition, an outer surface shape and an inner surface shape of the container from a lower end part 6 of a body part 1 to a bottom part 2 change curvedly and do not have a portion which changes by bending. An outer surface 11 of the lower end part 6 of the body part 1 and an outer surface 12 of an apex part 5 of the bottom part 2 are connected by a first curved line 13. The bottom part 2 has a thick part 15 which is recessed to a body part side toward a center of the bottom part 2 from the apex part 5. An outer surface of the thick part 15 and an outer surface of the apex part 5 are connected by a second curved line 17. A minimum curvature radius of the first curved line 13 is 7.5 mm or more. A minimum curvature radius of the second curved line 17 is 0.6 mm or more. When a thickness t1 of the body part 1 is 1, a thickness t2 of the apex part 5 is 1.6-2.4, and a thickness t3 of a center part 23 of the bottom part 2 is 3.8-4.8.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a container, and more particularly to a container having a bottle shape.

  Deposit cleaners for combustion chambers of automotive engines are known. Generally, deposit cleaners are sold in a form that is packed in a bottle-shaped container with a long neck, and the deposit cleaner in the container is supplied to the fuel tank by inserting the neck of the container into the fuel filler port of the automobile. Then, it is made to mix with fuel (patent document 1).

  The container described in Patent Document 1 has an elliptical cross section, but a circular cross section is also widely known.

  Such a deposit cleaner is generally produced in a factory that exists at a low altitude above sea level. In the production factory, the container is sealed with the container filled with the cleaner. At that time, the pressure in the container is about 1 atm. The material of the container is generally polyester.

Design Registration No. 1151767

  However, when such a deposit cleaner filled in a container is circulated in an area where the altitude is high, for example, the air pressure in that area is naturally less than 1 atm, and thus a pressure difference occurs between the inside and outside of the container. If the pressure difference increases, accidents such as the bottom of the container coming off may occur.

  In view of the above, an object of the present invention is to prevent an accident such as the bottom portion from falling out even if a pressure difference due to a difference in sea level altitude occurs between inside and outside a sealed container.

In order to achieve this object, a container formed of the polyester resin composition of the present invention, having a trunk part and a bottom part, and having a downward top part on the periphery of the bottom part relates to the longitudinal sectional structure of this container. ,
The outer surface shape and inner surface shape of the container from the lower end portion to the bottom portion of the trunk portion change in a curved manner, and do not have a portion that changes by bending,
The outer surface of the lower end portion of the trunk portion and the outer surface of the top portion of the bottom portion are connected by a first curve,
The bottom part has a thick part recessed from the top part toward the trunk part toward the center of the bottom part,
The outer surface of the thick part and the outer surface of the top part are connected by a second curve,
The minimum curvature radius of the first curve is 7.5 mm or more,
The minimum curvature radius of the second curve is 0.6 mm or more,
When the thickness of the body part is 1, the thickness of the top part is 1.6 to 2.4, and the thickness of the center part of the bottom part is 3.8 to 4.8.

  According to the container of the present invention, the polyester resin composition has a polyester resin as a main component, and this polyester resin has an ethylene terephthalate unit as a main component and contains 0.5 to 15 mol% of isophthalic acid as a subcomponent. Preferably it is.

  According to the container of the present invention, the polyester resin composition has a polyester resin as a main component, and the polyester resin has an ethylene terephthalate unit as a main component and 1,4-cyclohexanedimethanol as a subcomponent is 0.2 to 15 mol%. It is suitable to contain.

  According to the container of the present invention, the polyester resin composition has a polyester resin as a main component, and this polyester resin has an ethylene terephthalate unit as a main component, and 0.5 to 12 mol% of isophthalic acid and 1,4- It is preferable that it contains 0.2 to 10 mol% of cyclohexanedimethanol.

  According to the present invention, since the shape of the container is as described above, the strength of the portion from the lower end portion of the trunk portion to the bottom portion can be made sufficient. Even if there is a pressure difference due to the difference between the two, it is possible to prevent the occurrence of an accident such as the bottom part coming off.

  And according to this invention, while using the above-mentioned polyester resin composition, while a blow moldability improves, the high intensity | strength state can be maintained more reliably in the container made into said form. Furthermore, the impact resistance of the resulting container can be improved.

It is sectional drawing of the principal part of the container of embodiment of this invention. It is whole sectional drawing of the container of FIG.

  The container of the present invention shown in FIG. 2 integrally includes a cylindrical body portion 1, a circular bottom portion 2, and a slightly longer narrow neck portion 3 formed above the body portion 1. . A spout 4 is formed at the tip of the neck 3. Although details will be described later, the container is formed of a polyester resin composition.

  The container is filled with contents such as a deposit cleaner, and the spout 4 is sealed and circulated in the sealed state.

  The illustrated container is formed into a predetermined shape described later by, for example, direct blow molding using the above-described polyester resin composition, thereby maintaining a required high strength state.

The polyester resin composition has a polyester resin (A) as a main component, the polyester resin (A) has an ethylene terephthalate unit as a main component, and isophthalic acid as an accessory component in an amount of 0.0.
By containing 5 to 15 mol%, the blow moldability of the polyester resin composition is improved, whitening due to crystallization during blow molding can be prevented, and the high strength state is more reliably maintained. can do.

  The polyester resin composition is mainly composed of a polyester resin (B), and this polyester resin (B) is mainly composed of an ethylene terephthalate unit, and contains 1,4-cyclohexanedimethanol in an amount of 0.2 to 15 mol% as a subcomponent. By containing, the blow moldability of the polyester resin composition is improved, whitening due to crystallization at the time of blow molding can be prevented, and after maintaining the high strength state as described above, Can improve impact resistance.

  In addition, the polyester resin composition is composed mainly of an ethylene terephthalate unit and contains, as subcomponents, 0.5 to 12 mol% of isophthalic acid and 0.2 to 10 mol% of 1,4-cyclohexanedimethanol ( By having C) as a main component, the blow moldability of the polyester resin composition is improved, whitening due to crystallization during blow molding can be prevented, and the high strength state as described above is maintained. In addition, the impact resistance can be further improved.

  The polyester resin composition forming the container of the present invention will be described.

  First, the polyester resin (A) will be described. The polyester resin (A) in the present invention is mainly composed of an ethylene terephthalate unit and is mixed or copolymerized with isophthalic acid as a subcomponent, and among them, it is preferable to copolymerize. The content of isophthalic acid is preferably 0.5 to 15 mol%, more preferably 1 to 12 mol%, and even more preferably 2 to 8 mol%. By containing (copolymerization) isophthalic acid, the crystallization speed of the polyester resin can be adjusted to be suitable for blow molding, and whitening due to crystallization during blow molding can be prevented.

  If the content of isophthalic acid is less than 0.5 mol%, the resin crystallization speed will be high, and when blow molding, the molded product will crystallize and whiten, which tends to be inferior in transparency. . On the other hand, when the content of isophthalic acid exceeds 15 mol%, the resin becomes amorphous, and therefore, when a polyester resin is produced, drying at a high temperature and solid phase polymerization tend to be difficult. Alternatively, blocking is likely to occur during high-temperature drying or in the solid phase polymerization process.

  In the polyester resin (A), it is preferable that 60 mol% or more of the dicarboxylic acid component is terephthalic acid. Among these, the proportion of terephthalic acid is more preferably 70 mol% or more, and even more preferably 80 mol% or more. When the proportion of terephthalic acid is less than 60 mol%, the crystallinity of the resin is lowered and the resin tends to be amorphous.

  Examples of dicarboxylic acid components other than terephthalic acid and isophthalic acid include phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, adipic acid, 1,4-cyclohexanedicarboxylic acid, sebacic acid, dimer acid, and the like. These acids may be used in combination, or ester-forming derivatives of these acids may be used.

  On the other hand, the glycol component in the polyester resin (A) is preferably 80 mol% or more of ethylene glycol, more preferably 85 mol% or more of ethylene glycol, and even more preferably 95 mol% or more of ethylene glycol. Is more preferable. Examples of glycol components other than ethylene glycol include neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexamethylenediol, diethylene glycol, 1,4-cyclohexanedimethanol, dimer diol, An ethylene oxide adduct of bisphenol A or bisphenol S can be used.

  When the proportion of ethylene glycol in the glycol component is less than 80 mol%, the resin crystallinity is lowered and the resin tends to be amorphous, which is not preferable.

The polyester resin (B) will be described.
The polyester resin (B) in the present invention is mainly composed of an ethylene terephthalate unit and is mixed or copolymerized with 1,4-cyclohexanedimethanol as a subcomponent, and among them, it is preferable to copolymerize. The content of 1,4-cyclohexanedimethanol (hereinafter sometimes abbreviated as “CHDM”) is preferably 0.2 to 15 mol%, and more preferably 0.5 to 10 mol%. More preferably, it is still more preferably 1 to 8 mol%.

  By containing (copolymerizing) CHDM, the crystallization speed of the polyester resin can be adjusted to be suitable for blow molding, and whitening due to crystallization during blow molding can be prevented. And the impact resistance of the container obtained can be improved.

  If the CHDM content is less than 0.2 mol% or more than 15 mol%, the crystallization speed cannot be adjusted, and the impact resistance of the container obtained by blow molding is improved. It is difficult to do.

  The proportion of ethylene glycol in the polyester resin (B) is preferably 70 mol% or more, and more preferably 80 mol% or more. As glycol components other than ethylene glycol and CHDM, for example, neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexamethylenediol, diethylene glycol, ethylene oxide adduct of bisphenol A, dimer Examples include diols.

  If the proportion of ethylene glycol in the glycol component is less than 70 mol%, the crystallinity of the resin composition is lowered and it is likely to be amorphous, which is not preferable. On the other hand, when the proportion of ethylene glycol exceeds 99 mol%, the amount of copolymerization of CHDM decreases, so it is difficult to adjust the crystallization rate and it is difficult to improve the impact resistance of the resulting container. Become.

  As the dicarboxylic acid component in the polyester resin (B), the proportion of terephthalic acid is preferably 70 mol% or more, and the proportion of terephthalic acid is more preferably 80 mol% or more, more preferably 90 mol% or more. preferable. When the proportion of terephthalic acid is less than 70 mol%, the crystallinity of the resin is lowered, and it tends to be amorphous.

  Examples of dicarboxylic acid components other than terephthalic acid include phthalic acid, phthalic anhydride, isophthalic acid, naphthalenedicarboxylic acid, adipic acid, 1,4-cyclohexanedicarboxylic acid, sebacic acid, dimer acid, and the like. These acids may be used in combination, or ester-forming derivatives of these acids may be used.

The polyester resin (C) will be described.
The polyester resin (C) in the present invention is mainly composed of an ethylene terephthalate unit, and is a mixture or copolymerization of isophthalic acid and 1,4-cyclohexanedimethanol as subcomponents. It is preferably obtained by mixing a polyester resin and a polyester resin copolymerized with CHDM.

  The content of isophthalic acid in the polyester resin (C) is preferably 0.5 to 12 mol%, more preferably 1 to 10 mol%, and more preferably 2 to 8 mol%. Is more preferable. The CHDM content in the polyester resin (C) is preferably 0.2 to 10 mol%, more preferably 0.5 to 9 mol%, and even more preferably 1 to 8 mol%. Is more preferable.

  When the content of isophthalic acid and 1,4-cyclohexanedimethanol in the polyester resin (C) is outside the above range, it is difficult to adjust the crystallization speed and it is difficult to improve blow moldability. Moreover, it is difficult to improve the impact resistance of the container obtained by blow molding.

  The polyester resin (C) is preferably obtained by mixing the polyester resin (A) and the polyester resin (B).

  The intrinsic viscosity of the polyester resins (A) to (C) is preferably 0.5 to 1.3 dL / g, and more preferably 0.8 to 1.2 dL / g. When the intrinsic viscosity is less than 0.5 dL / g, the intrinsic viscosity of the obtained resin composition becomes too low, and the drawdown of the parison becomes large at the time of blow molding, and the molding tends to be difficult. Moreover, even if a molded body (container) can be obtained, it tends to be inferior in impact resistance. On the other hand, if the intrinsic viscosity exceeds 1.3 dL / g, the intrinsic viscosity of the resulting resin composition becomes too high, and it is necessary to raise the molding temperature, resulting in poor color tone and transparency of the resulting molded product (container). It is easy and impact resistance is easy to fall.

  The polyester resin composition of the present invention can be mainly composed of any of the above-described polyester resin (A), polyester resin (B), and polyester resin (C). It is preferable to contain an agent as necessary. The content of the polyester resin in the polyester resin composition is preferably 90% by mass or more, and more preferably 95% by mass or more.

  Additives contained in the polyester resin composition of the present invention include antioxidants, anti-coloring agents, cobalt compounds, fluorescent brighteners, color improvers such as dyes, matting agents such as titanium dioxide, plastics Agents, pigments, antistatic agents, flame retardants, dyeing agents, and the like, and one or more of them may be added.

Especially, it is preferable to contain 0.05-1.0 mass% of hindered phenolic antioxidants as antioxidant, and it is more preferable to contain 0.1-0.8 mass% especially.
By including a hindered phenolic antioxidant in the resin composition, the melt viscosity and thermal stability of the resin composition are improved when a container is obtained by direct blow molding, and color tone and transparency with good operability are obtained. Can be obtained.

  The form of the container based on the present invention, that is, the longitudinal sectional structure will be described in detail. As shown in FIGS. 1 and 2, the bottom 2 has a downwardly facing top 5 at its periphery. The top 5 corresponds to the circular shape of the bottom 2 and is configured to be continuous in a circle along the circumferential direction of the bottom 2. When placing the container on a table or the like, the container is supported by the top portion 5 being in contact with the placement surface.

  The lower end portion 6 of the trunk portion 1 and the top portion 5 of the bottom portion 2 are connected to each other by a connecting portion 7. Both the outer surface shape and the inner surface shape of the container in the connecting portion 7 change in a curved manner. That is, the container has a configuration that does not have a portion where the shape is bent and changed in the longitudinal section of the container.

In detail, in the connection part 7, the outer surface 11 of the lower end part 6 of the trunk | drum 1 and the outer surface 12 of the top part 5 in the bottom part 2 are connected by the 1st curve 13 swelled toward the outer side of the container. . This first curve 13 can be, for example, an arcuate line as shown. In FIG. 1, R1 means the radius of curvature. The 1st curve 13 can also be made into the curve of forms other than circular arc shape. For the first curve 13, the minimum radius of curvature R1min can be set. When the first curve 13 is the arc-shaped line described above,
R1min = R1.

  As shown in the figure, the bottom 2 has a shape recessed from the top 5 toward the center of the bottom 2 toward the body 1. In the recessed portion 14, the bottom 2 constitutes a thick portion 15. The outer surface 16 of the thick portion 15 can be formed by a curved line such as a large arc. In the illustrated example, the outer surface 16 is formed by an arcuate line, and R0 is the radius of curvature.

The outer surface 16 of the thick portion 15 and the outer surface 12 of the top portion 5 are connected by a second curve 17 that swells toward the outside of the container. The second curve 17 can be, for example, an arc-like line as with the first curve 13. In FIG. 1, R2 means the radius of curvature. The second curve 17 can also be a curve other than an arc shape. Also for the second curve 17, the minimum curvature radius R2min can be set. If the second curve 17 is an arcuate line,
R2min = R2.

  In the illustrated type of container, the diameter of the body 1 is preferably 40 to 70 mm, more preferably 45 to 65 mm, and most preferably 50 to 65 mm. In that case, the first curve 13 needs to have a minimum radius of curvature R1min of 7.5 mm or more, preferably 8.0 mm or more, and more preferably 9.0 mm. Is more preferable. When the minimum curvature radius R1min is less than 7.5 mm, stress concentration tends to occur at the connecting portion 7 and the strength of the container is reduced. Further, the second curve 17 needs to have a minimum radius of curvature R2min of 0.6 mm or more, preferably 0.8 mm or more, and more preferably 0.9 mm or more. . If the minimum curvature radius R2min is less than 0.6 mm, the outer surface of the thick portion 15 and the outer surface 12 of the top portion 5 are connected in a state close to a bent state, and harmful stress concentration is likely to occur.

  In the connection part 7, the inner surface 18 of the lower end part 6 of the trunk | drum 1 and the inner surface 19 of the top part 5 in the bottom part 2 are connected by the 3rd curve 20 dented toward the outer side of the container. The third curve 20 is formed corresponding to the first curve 13 and is formed so that the thickness of the connecting portion 7 does not change abruptly. In the illustrated example, the third curve 20 is configured by an arc-shaped line having a center position different from that of the first curve 13. R3 is the radius of curvature. The radius of curvature R3 is preferably 7 mm or more, more preferably 8 mm or more, and even more preferably 8.5 mm or more. When the curvature radius R1 of the first curve 13 is 1, the curvature radius R3 of the third curve 20, that is, R3 / R1, is preferably in the range of 0.86 to 0.92.

  The inner surface 21 of the thick portion 15 and the inner surface 19 of the top portion 5 are connected by a fourth curve 22 that is recessed toward the outside of the container. The fourth curve 22 can be, for example, an arc-like line as with the third curve 20. R4 means the radius of curvature. The fourth curve 22 may be a curve other than an arc shape. The radius of curvature R4 is preferably 1.5 mm or more, more preferably 2.0 mm or more, and even more preferably 2.5 mm or more.

In the container of FIG. 1, the body 1 is formed with a uniform thickness t <b> 1 over the top and bottom.
In FIG. 1, t <b> 2 is the thickness of the top portion 5, and t <b> 3 is the thickness of the central portion 23 of the bottom portion 2. When the diameter of the trunk portion 1 is 40 to 70 mm as described above, when the thickness t1 of the trunk portion 1 is 1, the thickness t2 of the top portion 5, that is, t2 / t1, is 1.6-2. 4 is preferable, and 1.8 to 2.2 is particularly preferable. Further, the thickness t3 of the central portion 23 of the bottom portion 2, that is, t3 / t1, is in the range of 3.8 to 4.8, preferably 3.8 to 4.5.

  According to the present invention, by setting the dimensional relationship of each part as described above, even when a pressure difference occurs between the inside and outside of the container formed of the polyester resin composition, the maximum strain generated in the container is small. can do. Thereby, when the container is tightly sealed, it is possible to prevent the container from being damaged such as a bottom drop. In particular, by making the dimensional relationship of each part as described above and making the material of the container the above-mentioned specific polyester resin composition, it is possible to make the container even higher in strength and less distorted, and also in impact resistance. Can also be an excellent container.

  Hereinafter, the present invention will be described specifically by way of examples. Evaluation of characteristic values in the examples was performed as follows.

[Maximum strain]
As load conditions for the obtained container, the inside of the sealed container was 1 atm (0.101 MPa), and the outside of the container was 0.74 atm (0.075 MPa).

  After setting the conditions as described above, Autodesk Simulation Mechanical 2016 from Autodesk was used as the software for stress analysis, and analysis was performed using static analysis with linear materials. It was confirmed that stress acts on the connecting portion 7 between the body portion 1 and the bottom portion 2 of the container and a corresponding strain is generated. The maximum strain generated in the connecting portion 7 of the container was determined.

[Crack generation]
With respect to the container (the number of samples n = 10) after the measurement of the maximum strain, the presence or absence of occurrence of cracks in the bottom 2 and the connecting portion 7 was visually confirmed. The number of containers with cracks was evaluated.

(Impact resistance)
The impact resistance of the obtained container was evaluated as follows. That is, the obtained container (number of samples n = 100) was filled with 200 ml of tap water, and at room temperature, on the P tile, from a height of 100 cm, with the bottom of the container facing downward and the side facing downward. The molded product was dropped once. At this time, the impact resistance was evaluated by the number of containers that were not broken.

Example 1
As a polyester resin composition, SA-8339P (detailed composition: polyethylene terephthalate copolymerized with 6 mol% isophthalic acid, intrinsic viscosity 1.13 dL / g) manufactured by Unitika Co., Ltd., and a direct blow molding machine manufactured by Tahara Co., Ltd. were used. 2 by direct blow molding, the body 1 has a diameter of about 60 mm, the body has a height of about 100 mm, the neck 3 has a height of about 80 mm, the total height is about 200 mm, and the capacity is 250. A container made up to milliliters was obtained.

  Details of the dimensions of the container obtained are as follows: R0 is 120 mm, R1 is 10 mm, R2 is 1.0 mm, R3 is 8.76 mm, R4 is 2.50 mm, t1 is 0.66 mm, t2 is 1.26 mm, and t3 is 2.60 mm. When t1, t2, and t3 are represented by dimensionless numerical values, when t1 is 1, t2 is 1.91 and t3 is 3.94. When R1 was 1, R3 was 0.876.

  Table 1 shows a list of dimensions of the container of Example 1 and various evaluation results.

(Example 2)
Direct blow molding was performed in the same manner as in Example 1 except that the molding conditions were changed so that the dimensions of each part were as shown in Table 1.

  Table 1 shows a list of the dimensions of the container of Example 2 and the results of various evaluations.

(Comparative Examples 1-4)
Direct blow molding was performed in the same manner as in Example 1 except that the molding conditions were changed so that the dimensions of each part were as shown in Table 1.

  Table 1 shows a list of dimensions of the containers of Comparative Examples 1 to 4 and various evaluation results.

  In Comparative Examples 1 and 2, since the values of t2 and t3 when t1 was 1 were both large beyond the range of the present invention, the maximum strain generated in the container, that is, the connecting portion 7 was 0 in Comparative Example 1. .57%, and Comparative Example 2 was 0.64%, which was larger than Examples 1 and 2. The value of R3 when R1 was 1 was also less than the preferred range of the present invention (0.86 to 0.92).

  In Comparative Examples 3 and 4, the outer surface 16 of the thick wall portion 15 and the outer surface 12 of the top portion 5 are connected by a second curve 17 that bulges toward the outside of the container, as in the container of the present invention. Instead of a plane structure, the outer surface of the thick portion and the outer surface of the top portion are connected by a bent line. The inner surface of the thick portion and the inner surface of the top portion are connected by a corresponding bent line. For this reason, neither the second curve on the outer surface of the container nor the fourth curve on the inner surface of the container is present.

  As described above, in Comparative Examples 3 and 4, neither the second curve of the outer surface of the container nor the fourth curve of the inner surface of the container is formed, and the outer surface and inner surface of the thick portion and the outer surface and inner surface of the top portion are formed. Are both connected by a bent line. For this reason, the maximum strain generated in the container, that is, the connecting portion 7 was 0.67% in Comparative Example 3 and 0.50% in Comparative Example 4, which was larger than Examples 1 and 2. The value of R3 when R1 was 1 was also outside the preferred range of the present invention (0.86 to 0.92).

(Example 3)
Example 1 except that SA-839P (detailed composition: polyethylene terephthalate copolymerized with 6 mol% of 1,4-cyclohexanedimethanol, intrinsic viscosity 1.13 dL / g) manufactured by Unitika Ltd. was used as the polyester resin composition. Direct blow molding was performed in the same manner as described above.

  The dimensions and maximum strain of the container of Example 3 were the same as in Example 1. Table 1 shows a list of various evaluation results.

Example 4
As a polyester resin composition, SA-8339P (detail composition: polyethylene terephthalate copolymerized with 6 mol% of isophthalic acid, intrinsic viscosity 1.13 dL / g) manufactured by Unitika and SA-8939P (detail composition: 1) manufactured by Unitika Polyethylene terephthalate copolymerized with 6 mol% of 1,4-cyclohexanedimethanol, inherent viscosity 1.13 dL / g) was used in a mass ratio (SA-8339P / SA-8039P) 70/30. Direct blow molding was performed in the same manner as in Example 1.

  The dimensions and maximum strain of the container of Example 4 were the same as those of Example 1. Table 1 shows a list of various evaluation results.

(Example 5)
Direct blow molding was performed in the same manner as in Example 1 except that the molding conditions were changed so that the dimensions of each part were as shown in Table 1.

  Table 1 shows a list of dimensions of the container of Example 5 and various evaluation results.

  Since the containers of Examples 1 to 5 all had a maximum strain of 0.30% or less, the occurrence of cracks at the bottom 2 and the connecting portion 7 was small. The impact resistance was excellent. In particular, Examples 3 and 4 using a polyester resin containing 1,4-cyclohexanedimethanol as the polyester resin composition were excellent in impact resistance.

  On the other hand, since the maximum strain of the containers of Comparative Examples 1 to 4 was 0.50% or more, cracks occurred in the bottom 2 and the connecting portion 7. For this reason, when the pressure difference between the inside and outside of the container becomes large, an accident that the bottom of the container comes off easily occurs.

DESCRIPTION OF SYMBOLS 1 trunk | drum 2 bottom part 5 top part 7 connection part 13 1st curve 15 thick part 17 2nd curve t1 thickness t2 thickness t3 thickness

Claims (4)

A container having a trunk portion and a bottom portion and having a top portion facing downward on the periphery of the bottom portion, the container being formed of a polyester resin composition,
The outer surface shape and inner surface shape of the container from the lower end portion to the bottom portion of the trunk portion change in a curved manner, and do not have a portion that changes by bending,
The outer surface of the lower end portion of the trunk portion and the outer surface of the top portion of the bottom portion are connected by a first curve,
The bottom part has a thick part recessed from the top part toward the trunk part toward the center of the bottom part,
The outer surface of the thick part and the outer surface of the top part are connected by a second curve,
The minimum curvature radius of the first curve is 7.5 mm or more,
The minimum curvature radius of the second curve is 0.6 mm or more,
When the thickness of the body portion is 1, the top portion has a thickness of 1.6 to 2.4, and the bottom portion has a central portion with a thickness of 3.8 to 4.8. .   2. The polyester resin composition comprising a polyester resin as a main component, wherein the polyester resin contains ethylene terephthalate units as a main component and 0.5 to 15 mol% of isophthalic acid as a subcomponent. Container as described.   The polyester resin composition is mainly composed of a polyester resin, and this polyester resin is mainly composed of ethylene terephthalate units and contains 0.2 to 15 mol% of 1,4-cyclohexanedimethanol as a subcomponent. The container according to claim 1. The polyester resin composition has a polyester resin as a main component, and this polyester resin is mainly composed of an ethylene terephthalate unit, with 0.5 to 12 mol% of isophthalic acid and 1,4-cyclohexanedimethanol 0.2 to 10 as subcomponents. The container according to claim 1, comprising: mol%.

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