JPH04215935A - Carbonated beverage bottle made of saturated polyester and its manufacture - Google Patents

Abstract

PURPOSE:To prevent rupture from happening on a bottle even when a carbonated beverage is filled in the bottle and it is stored under a high temperature and high humidity condition for a long period of time by specifying the thickness and density at the upper shoulder of a bottle. CONSTITUTION:A bottle 1 consists of a mouth tap part 2, upper shoulder part 3, body part 4, lower shoulder part 5 and bottom part 6. For such a bottle 1, the thickness at the upper shoulder part 3 (a location which is 15mm lower than a support ring, along the bottle surface) is not higher than 0.35mm, preferably, approximate 0.35-0.30mm. Also, the density of a saturated polyester to form the bottle is 1.367-1.390g/cm<2>, and it is desirable to be approximate 1.367-1.385g/cm<2>.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD OF THE INVENTION The present invention relates to a saturated polyester carbonated beverage bottle, and more particularly to a saturated polyester carbonated beverage bottle with excellent stress crack resistance and a method for manufacturing the same.

0002

TECHNICAL BACKGROUND OF THE INVENTION Conventionally, glass has been widely used as a material for containers for carbonated beverages such as cola and beer. However, since glass containers are expensive to manufacture, a method of collecting empty containers after normal use and recycling them is adopted. In addition, glass containers are heavy, which increases transportation costs, and they also have drawbacks such as being easily damaged and requiring careful handling.

[0003] In order to eliminate such drawbacks of glass containers, there has been a rapid shift from glass containers to plastic containers in recent years. Various plastics are used as materials for containers, depending on the type of contents and the purpose of use. Among these plastic materials, saturated polyester resins such as polyethylene terephthalate have excellent mechanical strength, heat resistance, and transparency. It is used as a material for carbonated beverage containers because of its excellent gas barrier properties.

However, although carbonated beverage bottles made of saturated polyester such as polyethylene terephthalate have excellent mechanical strength and transparency, bottles manufactured under specific molding conditions rarely break, especially in the summer. Ta. If a bottle were to be damaged in the market, it would not only degrade the product's image but also be dangerous, so preventing bottle breakage is extremely important from a practical standpoint.

[0005] The inventors of the present invention have conducted extensive research into the causes of such damage to saturated polyester bottles.
It has been found that bottles are most often damaged in the height direction at the upper shoulder, which is 10 to 20 mm from the bottom end of the spout, and that they are often damaged under high temperature and high humidity conditions. Further studies based on the above findings revealed that the damage to saturated polyester bottles as described above is almost never caused by the chemical structure of the saturated polyester, and that the saturated polyester on the upper shoulder of the bottle is The present invention was completed based on the discovery that if the material has the same physical properties, damage to the bottle can be almost completely prevented.

[0006]

OBJECTS OF THE INVENTION The present invention aims to solve the above-mentioned problems in the prior art. It is an object of the present invention to provide a carbonated beverage bottle made of saturated polyester that does not cause damage to the bottle, and a method for manufacturing the bottle.

[0007]

SUMMARY OF THE INVENTION The saturated polyester carbonated beverage bottle according to the present invention is a saturated polyester bottle consisting of a spout, an upper shoulder, a trunk, a lower shoulder, and a bottom. It is characterized by having a wall thickness of 0.35 mm or less at a position 15 mm below the bottle surface, and a density of 1.367 to 1.390 g/cm3.

[0008] In this saturated polyester bottle, since the saturated polyester in the upper shoulder has specific physical properties, this saturated polyester bottle is filled with a carbonated beverage and can be stored for a long time under hot and humid conditions. Even if it is done,
The bottle will not be damaged.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The saturated polyester carbonated beverage bottle according to the present invention will be described below. The saturated polyester used as a raw material for the bottle according to the present invention includes terephthalic acid or its ester-forming derivatives (for example, lower alkyl esters, phenyl esters, etc.)
and ethylene glycol or its ester-forming derivative (for example, monocarboxylic acid ester ethylene oxide) is preferably used. The polyethylene terephthalate may be copolymerized with less than about 20 mole percent of other dicarboxylic acids or glycols.

Such dicarboxylic components include, for example, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, and diphenoxyethane dicarboxylic acid; adipic acid, sebacic acid,
It is derived from aliphatic dicarboxylic acids such as azelaic acid and decanedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

Glycol components include aliphatic glycols such as trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol decamethylene glycol; alicyclic glycols such as cyclohexanedimethanol; bisphenols; hydroquinone, 2,2-bis(
It is derived from aromatic diols such as 4-β-hydroxyethoxyenyl)propane.

Polyethylene terephthalate, which is particularly preferably used in the present invention, will be explained below. That is, preferred polyethylene terephthalate has the general formula [I]

[0013]

[Chemical formula 1]

The content of the ethylene terephthalate component unit (a) represented by: 95.0 to 98.6 mol%, preferably 97.0 to 98.5 mol%, more preferably 9
It is in the range of 7.3 to 98.3 mol%, and has the general formula [II]

[0015]

[Case 2]

The content of the dioxyethylene terephthalate component unit (b) represented by: 1.4 to 5.0 mol%
, preferably 1.5 to 3.0 mol%, more preferably 1
．． It is in the range of 7 to 27 mol%.

Such a preferable polyethylene terephthalate comprises ethylene terephthalate component units (a) represented by the above general formula [I] and dioxyethylene terephthalate component units (b) represented by the above general formula [II].
) are arranged randomly to form ester bonds, thereby forming a substantially linear polyester. The polyethylene terephthalate is substantially linear;
This is confirmed by dissolving the polyethylene terephthalate in o-chlorophenol.

The intrinsic viscosity [η] of such preferable polyethylene terephthalate measured in o-chlorophenol at 25° C. is 0.60 to 0.90 dl/g, preferably 0.70 to 0.87 dl/g, or more. Preferably 0.72
It is desirable to be in the range of ~0.85 dl/g.

The bottle for carbonated beverages made of saturated polyester according to the present invention has a spout 2, an upper shoulder 3, as illustrated in FIG.
, a trunk 4, a lower shoulder 5 and a bottom 6. In such a bottle 1, the wall thickness at the upper shoulder portion 3 (a position 15 mm below the support ring along the bottle surface) is 0.35 mm or less, preferably 0.34 to 0.30 m.
m, more preferably about 0.32 to 0.31 mm.

Further, in the present invention, the density of the saturated polyester forming the bottle as described above is 1.367 to 1.39.
0g/cm3, preferably 1.367-1.385g
/cm3, more preferably 1.367-1.380g
/cm3 is desirable.

Furthermore, in the saturated polyester carbonated beverage bottle of the present invention, the orientation coefficient (fb) at the upper shoulder portion is as follows:
Usually -0.45 to -0.53, preferably -0.
45 to -0.50, more preferably -0.45 to
-0.48.

Note that the orientation coefficient (f
b) is measured as follows. That is, in the bottle 1 shown in FIG. 1, a wall surface was cut from a portion 15 mm below the bottom surface of the support ring 8 along the bottle, and using this, the orientation coefficient was measured by X-ray diffraction.

[0023] When measuring the orientation coefficient, CuKα, 40k
Transmission method was used using V-200mA, point focus, textile table with pulse motor, PSPC (multi-position sensitive detector), and collimator [1 mmφ, 2θ/θ (2θ = 19.5°)]. . fb = -1 means that the molecular chains are oriented in the vertical direction of the bottle, fb = 0 means that the molecular chains are oriented randomly in the plane of the bottle, fb = 1 means that the molecular chains are oriented in the circumferential direction of the bottle.

Furthermore, the bottle 1 according to the present invention has a stretch index defined as below of 130 cm or more, preferably 140 to 230 cm, more preferably 150 to 230 cm.
It is desirable that it be stretched to 220 cm.

[0025]

[Math 1]

The stretching index of the bottle will be explained below. 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 of the bottle 1 below the support ring 8, 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 portion 2, specifically, the internal volume of the preform 7 below the support ring 8, and is the internal volume of the preform 7 excluding the plug portion 2. Specifically, it means the internal volume of the preform below the virtual straight line 9.

Furthermore, the inner surface area of the stretched bottle is larger than that of the spout 2.
It is the inner surface area of the stretched bottle 1 excluding
It is the inner surface area of the stretched bottle below the support ring 8 of the bottle 1, and more specifically means the inner surface area of the bottle below the imaginary straight line 9.

The inner surface area of the stretched bottle (excluding the inner surface area of the spout) can be determined by dividing the bottle, detecting the surface shape with a three-dimensional measuring machine, dividing it into minute parts, and integrating the areas of the minute parts. It can be measured by the method. Note that when the stretched bottle has a simple shape, the inner surface area can be determined as an approximate value by assuming that the body of the bottle is a cylinder, and assuming that the lower and upper parts of the bottle are hemispheres.

Therefore, the stretching index of the above-mentioned stretched bottle is determined by the inner surface area of the stretched bottle (excluding the inner surface area of the spout), the internal volume of the stretched bottle (excluding the volume of the spout), and the unstretched bottle. Internal volume (excluding the volume of the spout)
It can be calculated by finding . Note that the internal volume of the bottle can be easily measured by filling it with a liquid such as water.

[0031] The units of f value and stretch index are cm-1 and cm, respectively. Next, a method for manufacturing a saturated polyester carbonated beverage bottle according to the present invention will be described.

The saturated polyester carbonated beverage bottle according to the present invention can be manufactured using, for example, the above-mentioned saturated polyester in the following manner. First, a preform for forming a bottle is manufactured using a saturated polyester as described above. This preform can be obtained from saturated polyester by a conventionally known method. The heating temperature of saturated polyester for forming the preform is 9
It is preferable that it is 0-110 degreeC.

A bottle is manufactured by blow-molding the bottle-forming preform as described above in a blow mold so that the stretch index is 130 cm or more. Next, the obtained stretched bottle is heat set in a blow mold at a mold temperature of 140 to 160°C for 5 to 25 seconds, preferably 5 to 20 seconds.

By applying heat-setting treatment to the bottle in this way, even if the bottle is left in high temperature and high humidity conditions for a long time, the orientation coefficient of the upper shoulder part hardly changes, and the stress crack resistance is improved. You can get a bottle with excellent quality.

The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples. The stress crack resistance of the bottle is measured as follows.

That is, after filling a bottle with 1480 ml of water, this water was adjusted to a CO2 concentration of 4 gas volume by the citric acid-baking soda method. Then, leave it in an oven at 40°C and 90% relative humidity for 1
After 1 day, 3 days, 7 days, and 30 days, cracks occurring on the upper shoulder of the bottle (15 to 20 mm below the support ring) are visually observed.

[0037]

[Example 1] Polyethylene terephthalate (density 1.3
40 g/cm 3 and intrinsic viscosity [η] 0.85) was molded using a molding machine M-100A manufactured by Meiki Seisakusho Co., Ltd. to obtain a preform for bottle molding. The molding temperature at this time is 270~2
The temperature was 80°C.

Next, the preform obtained as described above was molded using a LB-01 molding machine manufactured by CORPOPLAS to obtain a biaxially stretched bottle. The preform was heated with an attached infrared heater, and the surface temperature was 90 to 110°C.

After the preform obtained in this way is stretched in a blow mold, it is brought into contact with a mold heated to 140 to 160°C for 5 to 20 seconds to perform a heat setting treatment, and the mold is I took it out.

The wall 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 density of the polyethylene terephthalate forming the bottle (measured by density gradient tube method) was 1.370 g/cm3.

The internal volume of the unstretched preform (excluding the volume of the spout) was 15 cm3, and the internal volume of the obtained bottle (excluding the volume of the spout) was 1484 cm3. The inner surface area of the stretched bottle (excluding the inner surface area of the spout) was 678 cm2. Therefore, the stretch index is calculated as follows.

[0042]

[Math 2]

The stress crack resistance of the bottle thus obtained was evaluated and the orientation coefficient of the shoulder was measured. The orientation coefficient was measured 15 mm below the bottom surface of the support ring along the bottle.

The results are shown in Table 1.

[0045]

[Comparative Example 1] A bottle was manufactured in the same manner as in Example 1, except that the heat setting treatment was not performed in Example 1, and the stress crack resistance of the bottle was evaluated and the shoulder The orientation coefficient was measured.

The results are shown in Table 1.

[0047]

[Table 1]

[Brief explanation of the drawing]

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

[Explanation of symbols]

1 bottle 2. Spout part 3 Upper shoulder 4 Torso 5 Lower shoulder area 6 Bottom 8 Support ring

Claims (1)

[Claims] Claim 1: In a saturated polyester bottle for carbonated beverages consisting of a spout, an upper shoulder, a body, a lower shoulder, and a bottom, the upper shoulder (located 15 mm below the support ring along the bottle surface) The wall thickness is 0.35 mm or less, and the density is 1.367 to 1.390 g/cm3
A carbonated beverage bottle made of saturated polyester, characterized by: