Synthetic resin bottle

Abstract

To provide a synthetic resin bottle in which the uniformity of a thickness of a DLC barrier film is enhanced while securing barrier properties.SOLUTION: A synthetic resin bottle 1 comprises a mouth 11, a shoulder 12, a trunk 13 and a bottom 14, and has a DLC barrier film 20 on an inner surface 1a. A thickness T1 of a barrier film 20a on an inner surface 11d of the mouth 11 is larger than a thickness T2 of a barrier film 20b on an inner surface 13a of the trunk 13 and is equal to or smaller than 300 nm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a synthetic resin bottle having a DLC barrier film on its inner surface. [Background technology]

[0002] BACKGROUND ART As containers for storing soft drinks such as carbonated drinks, water, sake, condiments such as soy sauce, and the like, synthetic resin bottles, which have a mouth, shoulder, body, and bottom, such as polyethylene terephthalate bottles (PET bottles), are widely used.

[0003] Synthetic resin bottles have poorer gas barrier properties than glass bottles, meaning that the shelf life of the contents can be shortened due to oxygen intrusion. They also have the disadvantage of easily losing carbon dioxide when carbonated drinks or other beverages are stored in them.

[0004] Therefore, in order to eliminate the above drawbacks, a DLC (Diamond Like Carbon) barrier film is applied to the inner surface of a synthetic resin bottle using, for example, a plasma CVD (plasma vapor deposition) technique to improve the gas barrier properties (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4725093 Summary of the Invention [Problem to be solved by the invention]

[0006] To improve the barrier properties, it is preferable to provide a uniform DLC barrier film on the entire inner surface of the synthetic resin bottle, including the mouth. Also, in synthetic resin bottles manufactured using recycled materials, it is preferable to provide a DLC barrier film on the entire inner surface, including the mouth, in order to suppress elution of components from the recycled materials.

[0007] However, it is difficult to apply a uniform DLC barrier film to the inner surface of the mouth, and therefore, if there are areas where the barrier film is thin due to unevenness, there are problems such as a decrease in barrier properties, a decrease in the suppression of components eluted from recycled materials, and even uneven coloring that impairs the appearance.The above-mentioned appearance problems are particularly noticeable in those in which the mouth is thermally crystallized (whitened).

[0008] The present invention addresses these issues and aims to provide a synthetic resin bottle that improves the uniformity of the thickness of the DLC barrier film while maintaining barrier properties. [Means for solving the problem]

[0009] The synthetic resin bottle of the present invention is a synthetic resin bottle having a mouth, a shoulder, a body, and a bottom, and having a DLC barrier film on its inner surface, characterized in that the film thickness of the barrier film on the inner surface of the mouth is greater than the film thickness of the barrier film on the inner surface of the body, and is 300 nm or less.

[0010] In the synthetic resin bottle of the present invention having the above-mentioned configuration, the mouth portion is preferably thermally crystallized.

[0011] In the synthetic resin bottle of the present invention, in the above configuration, it is preferable that a chamfered portion is provided between the inner surface of the mouth portion and the upper end surface of the mouth portion, and that the barrier film is not provided on the chamfered portion.

[0012] In the synthetic resin bottle of the present invention having the above configuration, the average thickness of the barrier film on the inner surface of the mouth is preferably 5 to 8 times the average thickness of the barrier film on the inner surface of the body. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a synthetic resin bottle in which the thickness uniformity of the DLC barrier film is improved while ensuring the barrier properties. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a vertical cross-sectional view of a synthetic resin bottle according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of the upper part of the synthetic resin bottle shown in FIG. [Figure 3] FIG. 3 is an enlarged view of the upper end portion of the mouth portion shown in FIGS. DETAILED DESCRIPTION OF THE INVENTION

[0015] A synthetic resin bottle 1 according to an embodiment of the present invention will be described in more detail below with reference to the drawings.

[0016] In the claims and this specification, "upper" means upper when the synthetic resin bottle 1 is in the upright position shown in Figure 1, and "lower" means the opposite.

[0017] The synthetic resin bottle 1 shown in Figure 1 is used to store liquid contents such as soft drinks such as carbonated drinks, water, sake, and seasonings such as soy sauce, and is a blow-molded product made of polyethylene terephthalate.

[0018] The synthetic resin bottle 1 may have a single layer structure of polyethylene terephthalate, but may also have a laminated structure of other synthetic resin materials.

[0019] Furthermore, the synthetic resin bottle 1 may be made of a synthetic resin other than polyethylene terephthalate.

[0020] Furthermore, the synthetic resin bottle 1 may be a double container (delaminated container) in which a shrinkable and deformable inner layer is peelably laminated inside an outer layer that forms the outer shell of the bottle. In this case, the synthetic resin bottle 1 may be formed by biaxially stretching blow molding a preform assembly in which an inner preform is incorporated inside an outer preform.

[0021] The synthetic resin bottle 1 has a bottle shape with a mouth 11, a shoulder 12, a body 13 and a bottom 14.

[0022] As shown in Figures 1 and 2, the mouth portion 11 is approximately cylindrical, and on its outer surface, a male thread 11a for attaching a cap (not shown), an annular protrusion 11b, and a neck ring 11c are integrally formed in this order from top to bottom.

[0023] As shown in Fig. 3, a chamfered portion 11f is provided between the inner surface 11d and the upper end surface 11e of the mouth portion 11. The chamfered portion 11f is an R-chamfer that is curved outwardly and convex in cross section. However, the chamfered portion 11f may also be a C-chamfer that is linear in cross section.

[0024] As shown in FIG. 2, the inner surface 11d of the mouth portion 11 below the chamfered portion 11f has a constant inner diameter.

[0025] In this embodiment, the mouth portion 11 is thermally crystallized (whitened), which gives the mouth portion 11 a milky white color and high strength.

[0026] As shown in FIGS. 1 and 2, the shoulder portion 12 has an umbrella shape that gradually widens in diameter downward, and is integrally connected to the lower end of the mouth portion 11.

[0027] The body portion 13 is generally cylindrical and has a larger diameter than the mouth portion 11 , and is integrally connected to the lower end of the shoulder portion 12 .

[0028] The bottom portion 14 is integrally connected to the lower end of the body portion 13 and closes the lower end of the body portion 13 .

[0029] The synthetic resin bottle 1 is provided with a DLC (Diamond Like Carbon) barrier film 20 on the entire inner surface 1a thereof. That is, the DLC barrier film 20 is provided on the entire inner surface 1a of the synthetic resin bottle 1, including the inner surface 11d of the mouth portion 11 and the inner surface 13a of the body portion 13.

[0030] The DLC barrier film 20 can be provided on the inner surface 1a of the synthetic resin bottle 1 by, for example, plasma CVD (plasma vapor deposition) using acetylene as a raw material gas.

[0031] In the synthetic resin bottle 1 according to this embodiment, the thickness T1 of the barrier film 20a on the inner surface 11d of the mouth portion 11 is greater than the thickness T2 of the barrier film 20b on the inner surface 13a of the body portion 13, and is 300 nm or less.

[0032] Here, the film thickness T1 of the barrier film 20a on the inner surface 11d of the mouth portion 11 being greater than the film thickness T2 of the barrier film 20b on the inner surface 13a of the body portion 13 means that the film thickness T1 of the barrier film 20a measured at any position on the inner surface 11d of the mouth portion 11 is greater than the film thickness T2 of the barrier film 20b measured at any position on the inner surface 13a of the body portion 13.

[0033] This configuration ensures the barrier properties of the entire inner surface 1a of the synthetic resin bottle 1, including the mouth 11, shoulder 12, body 13, and bottom 14, and also ensures that the barrier film 20a provided on the inner surface 11d of the mouth 11 has an appropriate film thickness T1 that is thicker than the barrier film 20b on the inner surface 13a of the body 13, thereby ensuring uniformity in the thickness of the DLC barrier film 20a on the inner surface 11d of the mouth 11. This prevents the barrier film 20a provided on the inner surface 11d of the mouth 11 from having uneven color and being mistaken for a foreign object.

[0034] In particular, even in a configuration in which the mouth portion 11 is thermally crystallized (whitened), as in the synthetic resin bottle 1 of this embodiment, by ensuring the uniformity of the thickness of the DLC barrier film 20a on the inner surface 11d of the mouth portion 11, it is possible to effectively prevent the color of the barrier film 20a from becoming uneven and being mistaken for a foreign object.

[0035] Furthermore, if the film thickness T1 of the barrier film 20a provided on the inner surface 11d of the mouth portion 11 is too thick, there is a risk that the barrier film 20a will peel off from the inner surface 11d of the mouth portion 11. However, in the synthetic resin bottle 1 of this embodiment, the film thickness T1 of the barrier film 20a provided on the inner surface 11d of the mouth portion 11 is set to 300 nm or less, thereby preventing the barrier film 20a from peeling off from the inner surface 11d of the mouth portion 11.

[0036] In particular, in the synthetic resin bottle 1 of this embodiment, the barrier film 20a is not provided on the chamfered portion 11f provided between the inner surface 11d of the mouth portion 11 and the upper end surface 11e of the mouth portion 11, which makes it possible to more effectively prevent the barrier film 20a from peeling off from the inner surface 11d of the mouth portion 11 from the upper end surface 11e side of the mouth portion 11.

[0037] Furthermore, since a barrier film 20 is provided on the entire inner surface 1a of the synthetic resin bottle 1, including the inner surface 11d of the mouth portion 11, even if the synthetic resin bottle 1 is formed using recycled materials, the barrier film 20 can prevent components of the recycled materials from leaching into the liquid contents.

[0038] In the synthetic resin bottle 1 according to this embodiment, the average film thickness of the barrier film 20a on the inner surface 11d of the mouth 11 is preferably 5 to 8 times the average film thickness of the barrier film 20b on the inner surface 13a of the body 13. This ensures sufficient barrier properties for the entire inner surface 1a of the synthetic resin bottle 1, including the mouth 11, shoulder 12, body 13, and bottom 14, while also ensuring uniformity in the thickness of the DLC barrier film 20a on the inner surface 11d of the mouth 11.

[0039] Furthermore, the thickness T2 of the barrier film 20b on the inner surface 13a of the body 13 is preferably 50 nm or less. This allows the barrier film 20b to follow the deformation, even if the body 13 is squeezed and shrinks during use, such as when pouring out the liquid content, and thus prevents cracks from occurring in the barrier film 20b. Furthermore, the thickness T2 of the barrier film 20b on the inner surface 13a of the body 13 is preferably 10 nm or more. This ensures sufficient barrier properties in the body 13. Note that the mouth 11 is a non-stretched portion that is not stretched during blow molding, and is therefore less likely to deform relative to the body 13, which is a stretched portion. Therefore, even if the thickness T1 of the barrier film 20a on the inner surface 11d of the mouth 11 is greater than the thickness T2 of the barrier film 20b on the inner surface 13a of the body 13, peeling of the barrier film 20a on the inner surface 11d of the mouth 11 does not occur.

[0040] The present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit and scope of the present invention.

[0041] For example, the shape of the synthetic resin bottle 1 is not limited to the shape shown in the drawings, and may be any other shape as long as it has a mouth, a shoulder, a body, and a bottom.

[0042] Furthermore, in the above embodiment, the mouth portion 11 is thermally crystallized (whitened), but the mouth portion 11 may be configured not to be thermally crystallized.

[0043] Furthermore, in the above embodiment, a chamfered portion 11f is provided between the inner surface 11d of the mouth portion 11 and the upper end surface 11e of the mouth portion 11, and no barrier film 20a is provided on the chamfered portion 11f. However, the chamfered portion 11f may also be provided with a barrier film 20a, or no chamfered portion 11f may be provided. [Explanation of symbols]

[0044] 1. Synthetic resin bottle 1a Inner surface 11 Mouth 11a male thread 11b Convex part 11c neck ring 11d Inside 11e Top surface 11f Chamfered part 12 Shoulder 13 Torso 13a Inner surface 14 Bottom 20 Barrier Film 20a Barrier film 20b Barrier film T1 Film Thickness T2 film thickness

Claims

1. A synthetic resin bottle having a mouth, a shoulder, a body, and a bottom, and having a DLC barrier film on the inner surface, A synthetic resin bottle, characterized in that the thickness of the barrier film on the inner surface of the mouth portion is greater than the thickness of the barrier film on the inner surface of the body portion, and is 300 nm or less.

2. 2. The synthetic resin bottle according to claim 1, wherein the mouth portion is thermally crystallized.

3. 3. The synthetic resin bottle according to claim 1, wherein a chamfer is provided between the inner surface of the mouth portion and the upper end surface of the mouth portion, and the barrier film is not provided on the chamfer.

4. 4. The synthetic resin bottle according to claim 1, wherein the average thickness of the barrier film on the inner surface of the mouth portion is 5 to 8 times the average thickness of the barrier film on the inner surface of the body portion.

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