JPH0524815B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a polyester bottle and a method for producing the same, and more specifically to a biaxially oriented polyester bottle that has good gas barrier properties, particularly carbon dioxide gas barrier properties, and excellent drop impact resistance, and is particularly useful for food and beverage applications. This article relates to polyester bottles and their manufacturing method. [Prior art] Biaxially oriented polyethylene terephthalate bottles have traditionally had mechanical strength, gas barrier properties, transparency,
Because it has excellent properties such as chemical resistance, it is used as containers for beverages, foods, cosmetics, etc. However, the characteristics of this bottle may not be sufficient depending on how it is used. For example, if the bottle is filled with carbonated beverages or beer, if it is stored for a long time, the carbon dioxide gas in the content will gradually escape and the product value will decrease. This limits its field of use. Therefore, research has been conducted to improve the properties of biaxially oriented polyester bottles, particularly the carbon dioxide gas barrier properties, and various proposals have been made. As a method for improving carbon dioxide gas barrier properties, for example, a method of laminating a polymer with good gas barrier properties and polyethylene terephthalate (Japanese Patent Application Laid-Open No. 1989-1999)
-89326, etc.), and a method in which a polymer with good gas barrier properties is mixed with polyethylene terephthalate (Japanese Patent Laid-Open No. 60-76325, etc.) have been proposed.
However, the former laminated bottle has drawbacks such as weak adhesion between the polyethylene terephthalate layer and the barrier polymer layer in the body, resulting in layer peeling and large internal pressure deformation. However, the bottom of the latter bottle has a disadvantage of being complicated, and the bottom of the latter bottle has a low impact resistance, which causes the bottom to break when the bottle is dropped, both of which pose practical problems. [Object of the Invention] The object of the present invention is to solve such problems and provide a biaxially stretched polyester bottle that has excellent gas barrier properties, particularly carbon dioxide barrier properties, and excellent properties such as drop impact resistance and internal pressure deformation resistance, and the production thereof. It is about providing law. [Configuration/Effects of the Invention] According to the present invention, the main feature of the present invention is that the mouth or body of the bottle is made of 95 to 5% by weight of polyethylene terephthalate and has a carbon dioxide gas permeability coefficient of 1.0×10 at 30°C. ^-13 [cc・cm／ ^cm2・sec・cmHg]
Composition (a) containing 5 to 50 parts by weight of the following thermoplastic polymer
and the bottom part is made of polyethylene terephthalate, or a composition made of a layer (a) of composition (a) and polyethylene terephthalate or the thermoplastic polymer mixed with polyethylene terephthalate in a lower proportion than the composition (a) of the body part. A biaxially oriented polyester bottle characterized by having a laminated structure having at least a layer (b) of the material (b), and when producing the biaxially oriented polyester bottle, the bottle mouth or A bottomed preform in which the part corresponding to the body is made of the composition (a) above, and the part corresponding to the bottom is made of polyethylene terephthalate or has a laminated structure having at least the above layers () and (). This is achieved by a manufacturing method characterized in that it is used. In the present invention, polyethylene terephthalate is not only a homopolymer, but also a part of the terephthalic acid component, such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether carboxylic acid, diphenyl dicarboxylic acid, etc. Aromatic dicarboxylic acids such as sulfonic acid; alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid, etc.; aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, etc.; P-β-
Hydroxyethoxybenzoic acid, p-benzoic acid, ε
- one or more components of other difunctional carboxylic acids such as oxyacids such as oxycaproic acid, and/or a portion of the ethylene glycol component, such as trimethylene glycol, tetramethylene glycol,
Hexamethylene glycol, decamethylene glycol, neopentylene glycol, diethylene glycol, 1,1-dichlorohexane dimethylol, 1,4-cyclohexane dimethylol, 2,
It includes copolyesters substituted with one or more components of other glycols such as 2-bis(4-β-hydroxyethoxyphenyl)propane and bis(4-β-hydroxyethoxyphenyl)sulfonic acid. The total proportion of copolymerized components in the copolyester is preferably 2 mol % or less based on the total acid components. Among these, a homopolymer of polyethylene terephthalate is preferred. Moreover, it is preferable that polyethylene terephthalate has an intrinsic viscosity (o-chlorophenol, 35° C.) of 0.6 or more. The thermoplastic polymer mixed with polyethylene terephthalate in the present invention has a carbon dioxide permeability coefficient (Pco ₂ ) of 1.0×10 ^-13 at 30°C.
It must be less than [cc・cm/cm ²・sec・cmHg], and specifically, ethylene-vinyl alcohol copolymer (hereinafter abbreviated as EVOH) obtained by saponifying ethylene-vinyl acetate copolymer Olefin-vinyl alcohol copolymers such as olefin-vinyl alcohol copolymers such as olefin-vinyl alcohol copolymers, metaxylylene group-containing polyamides such as polycondensates of metaxylylene diamine and adipic acid (hereinafter sometimes abbreviated as PA-M), and polyethylene isophthalate (hereinafter abbreviated as PEI). example). These can be used alone or in combination of two or more. The above olefin-vinyl alcohol copolymer has an olefin content of 10 to 50 mol%, particularly 20 to 50 mol%, from the viewpoint of moldability etc.
45 mol% is preferable, and the degree of saponification is 90%.
The above are preferred. Pco ₂ [cc・cm/cm ²・
sec・cmHg] is shown in the table below.
This table also includes Pco ₂ of polyethylene terephthalate (PET) for reference.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples. The measurement conditions for the main physical property values are as follows. (1) Intrinsic viscosity [ ]: Measured at 35°C using o-chlorophenol as a solvent. (2) Carbon dioxide permeability coefficient Carbon dioxide permeability was measured in an atmosphere of 30°C using a GPM-200 gas permeability measuring device manufactured by Lyssy, Switzerland. (3) Drop impact resistance After filling a bottle with 1000g of water and 14g of citric acid, insert 14g of bicarbonate of soda weighed into a polyethylene bag into the bottle mouth without directly mixing it with the citric acid aqueous solution inside the bottle. Immediately cap the bottle with an aluminum cap. After capping, shake the bottle so that the bicarbonate of soda and citric acid aqueous solution inserted into the bottle are thoroughly mixed, and CO ₂ gas is generated.
The bottle is filled with an aqueous solution in which CO ₂ gas is dissolved under pressure. The resulting CO _2- filled bottle was kept at a temperature of 5°C, and after 24 hours, the bottle was dropped from a height of 1.8 meters onto a concrete floor with the bottom facing downwards, and the rupture rate of the bottle was examined. This ratio is expressed as rupture rate [%]. (4) Carbon dioxide gas barrier property A CO ₂ bottle is obtained in the same manner as in the measurement of drop impact resistance in (3) above. However, the CO ₂ Volume shown by the following formula is 4. After this CO ₂ -filled bottle is held in an atmosphere of a predetermined temperature and a predetermined humidity for a predetermined time, it is transferred to an atmosphere of 20°C, and the carbon dioxide pressure inside the bottle is measured while the temperature of the filled liquid is 20°C. From this measured value, the remaining CO ₂ volume is determined using a calibration curve. CO ₂ Volume = Vco ₂ / VH ₂ O (where, VH ₂ O: Volume of H ₂ O liquid in the bottle [ml]) Vco ₂ : CO ₂ dissolved in the H ₂ O liquid phase in the bottle
Converted gas volume [ml] at 0°C 1 atm) Examples-1 to 5 and Comparative Examples-1 to 5 PET dried with hot air at 160°C for 5 hours (IV = 0.75,
Tg=70℃) and E _V OH dried under vacuum at 130℃ for 3 hours.
(Product name: E _VAL -E) in the proportions shown in Table 1, and supplied to cylinders A and B of an ASB-50EX-T co-injection oriented blow molding machine manufactured by Nissei ASB Machinery Co., Ltd., respectively. In a two-cavity mold cooled with 15°C cooling water at a molding temperature of 250 to 270°C, the first stage is from cylinder A, the second stage is from cylinder B,
In the third stage, multi-stage injection molding was performed from cylinder A to obtain a preform whose straight body and bottom had a cross-sectional state as shown in FIG. The injection pressure is: when injecting from cylinder A, the pressure of A is 70 kg/cm ² G, and the pressure of B is 5 kg/cm ² G, and when injecting from cylinder B, the pressure of B is 100 kg/cm 2 G. It was ² G. The preform has a cylindrical body with an outer diameter of 25 to 26
mm, wall thickness 3.5mm, total length 110mm, weight 35g, and has a bottomed end. The preform is further biaxially stretched and blow molded,
Internal volume 730ml to 740ml, body outer diameter 74mm, total height 234mm,
The body and bottom cross section with an internal thickness of 300 to 350 μm are the second
A biaxially stretched bottle as shown in the figure was obtained. The straight body and bottom of the resulting biaxially stretched bottle
The ratio of PET component to E _VOR component and cylinder A,
Table 1 shows the weight of the resin injected from cylinder B. Furthermore, the drop impact resistance and carbon dioxide gas barrier properties of the obtained biaxially stretched bottle were evaluated, and the results were summarized in the first
Shown in the table. From the table above, the bottles of Comparative Examples-1 to 4 have better carbon dioxide gas barrier properties than the bottles of Comparative Example-5, but have poorer drop impact resistance at low temperatures, while the bottles of Examples-1 to It can be seen that bottle No. 5 has good carbon dioxide gas barrier properties and good drop impact resistance. Examples -6 to -8 and Comparative Examples -6 to -7 E Instead of _VOH , metaxylylene group-containing polyamide (a polyamide whose repeating units are obtained by polycondensing metaxylene diamine and adipic acid; the following
A polyester bottle was molded in the same manner as in Example-1 and Comparative Example-1, except that the resin (denoted as PA-M) was used and the quantitative ratio was set to the values shown in Table 2.
The resulting bottles were evaluated. The results are shown in Table 2. As is clear from Table 2, Examples-6 to -
The polyester bottle number 8 has carbon dioxide gas barrier properties,
All have good drop impact resistance.

【table】

【table】

[Table] Examples -9 to -10 and Comparative Examples -8 to -9 PET (IV = 1.0) and PEI (IV - 0.75) were melted and extruded in the ratio shown in Table 3 beforehand, and the pellets were extruded on the cylinder A side. Example-1, except for use in
A bottle was molded and evaluated in the same manner as Comparative Example-1. The results are shown in Table 3. Example-11 Molding was carried out in the same manner as in Example-1 except that injection from cylinder A in the third stage was not performed.
A preform and a biaxially stretched bottle having cross-sectional shapes as shown in FIG. 4 were obtained. The carbon dioxide gas barrier property of the biaxially stretched bottle was as good as that of Example 1, but the rate of splitting during the drop impact resistance test was about 3 to 5%.

[Brief explanation of the drawing]

1 and 3 are schematic diagrams showing the cross-sectional state of the bottomed preform, and FIGS. 2 and 4 are schematic diagrams showing the cross-sectional state of the bottle.

Claims (1)

[Claims] 1. The mouth or body of the bottle is made of 95 to 50% by weight polyethylene terephthalate and has a carbon dioxide gas permeability coefficient of 1.0×10 ^-13 [cc・cm/cm ²・sec・cmHg] at 30°C.
Composition (a) containing 5 to 50% by weight of the following thermoplastic polymer:
and the bottom part is made of polyethylene terephthalate, or the composition (a) is made of a layer (a) of composition (a) and polyethylene terephthalate or the thermoplastic polymer is mixed with polyethylene terephthalate in a lower proportion than the body part composition (a). A biaxially oriented polyester bottle characterized by having a laminated structure having at least the layer (b). 2. Claim 1, wherein the thermoplastic polymer is at least one selected from the group of olefin-vinyl alcohol copolymer, metaxylylene group-containing polyamide, and polyethylene isophthalate.
Biaxially oriented polyester bottle as described in Section 2. 3 Patents in which the laminated structure at the bottom consists of a two-layer structure in the order of Layer (), Layer () from the inside of the bottle, a three-layer structure in the order of Layer (), Layer (), Layer (), or a compositional structure thereof. A biaxially stretched polyester bottle according to claim 1. 4. The biaxially oriented polyester bottle according to claim 1 or 3, wherein the proportion of the thermoplastic polymer in the composition (b) is 5% by weight or less.