JP3023388B2 - Saturated polyester carbonated beverage bottle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a saturated polyester carbonated drink bottle, and more particularly to a saturated polyester carbonated drink bottle excellent in stress crack resistance.

[0002]

BACKGROUND OF THE INVENTION In recent years, various plastics have been used as materials for bottles for carbonated drinks such as juices and colas, and among them, saturated polyesters such as polyethylene terephthalate are used for transparency, gas barrier properties, heat resistance and mechanical properties. Because of its excellent mechanical strength, it is widely used as a material for carbonated beverage containers.

[0003] However, in the case of carbonated beverage bottles made of a saturated polyester, bottles manufactured under specific molding conditions are rarely broken, especially in summer. Should a bottle break in the market, not only will the product image deteriorate,
Preventing the breakage of the bottle is extremely important in practical use because it can be dangerous.

[0004] The inventors of the present invention have conducted intensive studies on the cause of the breakage of such a saturated polyester bottle.
It has been found that the bottle is most likely to be broken in the height direction at the upper shoulder of 10 to 20 mm from the lower end of the plug, and that the bottle is frequently broken under high temperature and high humidity. Further studies based on the above findings showed that if the saturated polyester contained a certain amount of the polyfunctional compound component, even if the thickness of the upper shoulder was less than the specified thickness, the bottle was damaged. Have been found to be able to almost completely prevent the present invention, and have completed the present invention.

[0005]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems in the prior art. Even if the carbonated beverage is filled and stored for a long time under a high temperature and high humidity condition, the present invention aims to solve the problem. It is another object of the present invention to provide a saturated polyester carbonated beverage bottle in which the bottle is not damaged.

[0006]

SUMMARY OF THE INVENTION A saturated polyester carbonated beverage bottle according to the present invention is a saturated polyester bottle comprising a plug, an upper shoulder, a torso, a lower shoulder and a bottom. When the wall thickness is 0.35 mm or less (at a position 15 mm below the bottle surface) and the bottle has a dicarboxylic acid compound component unit of 100 mol parts, the polyfunctional compound component unit is 0.2%. ~ 1.0
Molar part contained, intrinsic viscosity [η] is 0.6 to 1.0 dl / g
Characterized by comprising a saturated polyester.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The saturated polyester carbonated beverage bottle according to the present invention will be described below. Examples of the saturated polyester used as the material of the bottle according to the present invention include terephthalic acid or an ester-forming derivative thereof (eg, lower alkyl ester, phenyl ester, etc.) and ethylene glycol or an ester-forming derivative thereof (eg, monocarboxylic acid ester ethylene). And the like, and a saturated polyester obtained from a polyfunctional compound.

Examples of the polyfunctional compound include trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol and the like, with trimethylolpropane being preferred. The content of the polyfunctional compound component unit in the saturated polyester is usually 0.2 to 1.0 mol part, preferably 0.2, when the dicarboxylic acid compound component unit constituting the saturated polyester is 100 mol parts. ~
It is 0.6 mole part, more preferably 0.2 to 0.4 mole part. When the content of the polyfunctional compound component unit is small, the molded bottle is inferior in stress crack resistance, and when the content is large, gelation is caused, resulting in poor appearance and poor moldability when molded into a bottle.

In such a saturated polyester resin, a dicarboxylic acid compound other than terephthalic acid and ethylene glycol and / or another dihydroxy compound may be copolymerized in an amount of 20 mol% or less.

[0010] In addition to terephthalic acid, examples of dicarboxylic acids used for copolymerization include aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid; adipic acid; Aliphatic dicarboxylic acids such as sebacic acid, azelaic acid and decane dicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acid. Specific examples of dihydroxy compounds used for copolymerization other than ethylene glycol include aliphatic glycols such as trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol; cyclohexane dimethanol; Alicyclic glycols; bisphenols; hydroquinone, 2,2-
And aromatic diols such as bis (4-β-hydroxyethoxyphenyl) propane.

[0011] Such a saturated polyester can be used to form a substantially linear polyester by forming an ethylene bond alone or a random arrangement of the ethylene terephthalate component unit and the dioxyethylene terephthalate component unit to form an ester bond. are doing. The fact that the saturated polyester is substantially linear is confirmed by the fact that the saturated polyester is dissolved in o-chlorophenol.

The intrinsic viscosity [η] of such a saturated polyester measured in o-chlorophenol at 25 ° C. is 0.1.
60 to 1.0 dl / g, preferably 0.6 to 0.9 dl / g
g, more preferably in the range of 0.6 to 0.8 dl / g. When the intrinsic viscosity [η] is in the above range, it is excellent in melt moldability and mechanical strength.

The melting point is usually from 210 ° C. to 265 ° C.
Preferably it is 220 to 260 ° C, and the glass transition temperature is usually 50 to 120 ° C, preferably 60 to 120 ° C.
It is desirable that the temperature is 100 ° C.

As shown in FIG. 1, the saturated polyester carbonated beverage bottle according to the present invention comprises a plug 2, an upper shoulder 3, a trunk 4, a lower shoulder 5, and a bottom 6.
Such a bottle can be manufactured using the saturated polyester as described above, for example, as follows.

First, a bottle-forming preform is manufactured using the above-mentioned saturated polyester. This preform can be obtained by a conventionally known method, for example, injection molding. Next, the preform for forming a bottle is heated and stretch-formed in a blow mold to produce a bottle.

In such a bottle, the thickness at the upper shoulder portion 3 (at a position 15 mm below the support ring along the bottle surface) is 0.35 mm or less, preferably 0.34 mm or less.
It is desirable that it is 0.30 mm, more preferably 0.32 to 0.31 mm. In the present invention, a saturated polyester bottle containing a specific amount of a structural unit derived from a specific polyfunctional compound and having an intrinsic viscosity [η] of 0.6 to 1.0 dl / g is used. 0.3 in wall thickness
Even if it is 5 mm or less, it is excellent in stress crack resistance, so that the weight of the bottle can be reduced.

The saturated polyester carbonated beverage bottle according to the present invention has a stretching index defined as follows, which is at least 130 cm, preferably 140 to 230 cm.
More preferably, the film is stretched to 150 to 220 cm.

[0018]

(Equation 2)

By using the saturated polyester as described above, the stretching index defined as above is stretched to 130 cm or more, and the thickness of the shoulder is 0.35 mm or less, so that the stress crack resistance is further improved. You can get a bottle.

Hereinafter, the stretching index of the bottle will be described. In FIG. 1, the content of the stretched bottle is the internal volume of the stretched bottle 1 excluding the spout 2, specifically, the internal volume below the support ring 8 of the bottle 1, and more specifically, , Means the internal volume of the bottle below the virtual straight line 9.

Further, the internal volume of the unstretched preform is the internal volume of the preform 7 excluding the plug 2, specifically, the internal volume below the support ring 8 of the preform 7. Specifically, it means the internal volume of the preform below the virtual straight line 9.

Further, the inner surface area of the stretched bottle is determined by
Is the internal surface area of the stretched bottle 1 excluding
It is the internal surface area of the stretched bottle below the support ring 8 of the bottle 1, more specifically, the internal surface area of the bottle below the virtual straight line 9.

The inner surface area of the stretched bottle (excluding the inner surface area of the spout) is determined by dividing the bottle, detecting the surface shape with a coordinate measuring machine, dividing the bottle into minute parts, and integrating the area of the minute parts. It can be measured by the method. If the stretched bottle has a simple shape, the inner surface area can be determined as an approximate value, assuming that the body of the bottle is a cylinder and the lower and upper portions of the bottle are each a hemisphere.

Accordingly, the stretching index of the above-mentioned stretched bottle is determined not only by the inner surface area (excluding the inner surface area of the plug portion), but also by the inner volume (excluding the inner volume of the plug portion) and the unstretched bottle of the stretched bottle. It can be calculated by calculating the internal volume (excluding the internal volume of the plug). The internal volume of the bottle can be easily measured by adding a liquid such as water.

The units of the f value and the stretching index are cm ^-1 and cm, respectively.

[0026]

The saturated polyester carbonated beverage bottle according to the present invention has a structural unit derived from a specific polyfunctional compound in an amount of from 0.2 to 1. Even if the bottle is made of a saturated polyester containing 0 mol part and having an intrinsic viscosity [η] of 0.6 to 1.0 dl / g, and the upper shoulder has a wall thickness of 0.35 mm or less, Since it is excellent in stress crack resistance, even if it is filled with carbonated beverage and stored for a long time under high temperature and high humidity conditions, the bottle will not be damaged.

[0027]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

In the present invention, the stress crack resistance of the bottle is measured as follows. That is, after filling the bottle with 1480 ml of water, the water is
The CO ₂ concentration is adjusted to 4 gas volume by the baking soda method. Then, it is left in an oven at 40 ° C. and 90% relative humidity, and after 1, 3 days, 7 days, and 30 days, cracks are visually observed at the upper shoulder portion of the bottle (at a position 15 to 20 mm below the support ring). I do.

[0029]

Example 1 Polyethylene terephthalate (trimethylolpropane content: 0.3 mol part, intrinsic viscosity [η]: 0.7)
5 dl / g) was molded with a molding machine M-100A manufactured by Meiki Seisakusho Co., Ltd. to obtain a preform for bottle molding. The molding temperature at this time was 280-290 ° C.

Next, the preform obtained as described above was molded using an LB-01 molding machine manufactured by CORPOPLAS to obtain a biaxially stretched bottle. The preform was heated by an attached infrared heater, and the surface temperature was 90 to 100 ° C.

The thickness (average of three points on the circumference) of the upper shoulder of this bottle (a position 15 mm below the support ring along the bottle surface) was 0.33 mm. The bottle thus obtained was evaluated for stress crack resistance.

The results are shown in Table 1.

[0033]

Comparative Example 1 Polyethylene terephthalate containing no trimethylolpropane (intrinsic viscosity [η] 0.75 dl)
/ G), except that a bottle was produced in the same manner as in Example 1, and the stress crack resistance of the bottle was evaluated in the same manner as in Example 1.

The results are shown in Table 1.

[0035]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a bottle according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bottle 2 Spout 3 Upper shoulder 4 Trunk 5 Lower shoulder 6 Bottom 8 Support ring

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI C08J 5/00 CFD C08J 5/00 CFD // B29K 67:00 C08L 67:02 (56) References JP-A-4-337350 ( JP, A) JP-A-4-331148 (JP, A) JP-A-4-126220 (JP, A) JP-A-3-205447 (JP, A) JP-A-60-134840 (JP, A) JP 56-74438 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29C 49/00-49/80

Claims (2)

(57) [Claims] 1. A saturated polyester carbonated beverage bottle comprising a spout, an upper shoulder, a torso, a lower shoulder and a bottom, wherein the upper shoulder (1 below the support ring along the surface of the bottle).
(A position 5 mm below) is 0.35 mm or less, and the bottle contains 1 unit of the dicarboxylic acid compound component.
When the amount is 00 mol parts, the polyfunctional compound component unit is contained in an amount of 0.2 to 1.0 mol parts, and the intrinsic viscosity [η] is 0.6 to 1.0.
A saturated polyester carbonated beverage bottle comprising a saturated polyester in a range of 1.0 dl / g. 2. The saturated polyester carbonated beverage bottle according to claim 1, wherein the stretch index is stretched to 130 cm or more as defined below. (Equation 1)