JP4769430B2 - Plastic cap - Google Patents

Description

  The present invention relates to a plastic cap having improved shielding properties against malodorous or odorous components generated from fungicides and the like.

  Conventionally, plastic bottles made of a polyester resin have been used for various applications as packaging containers in terms of light weight, impact resistance, and cost. In such a plastic bottle, oxygen permeation through the vessel wall occurs in an order that cannot be ignored, and this has been a problem in terms of storage stability of the contents. Plastic bottles have been used for the contents of varieties, and beverages such as shochu, for example, have been sold in plastic bottles.

In addition, for a plastic cap made of a polyolefin resin fastened to a plastic bottle, gas barrier properties have been studied. For example, the cap itself has a multilayer structure including a gas barrier layer (see Patent Document 1), A barrier film, sheet or disk provided between the liner (see Patent Documents 2 to 5), and a liner material provided on the inner surface of the cap has a multilayer structure including a gas barrier material or a gas barrier layer ( Patent Documents 6 and 7) have been proposed.
Japanese Utility Model Publication No. 5-81059 JP-A-2-117349 Patent No. 3224170 JP-A-9-77101 Actual Kaihei 8-9001 JP-A-11-278533 JP 2003-104406 A

  By the way, a packaging body in which a plastic bottle filled with a content is fastened and sealed with a plastic cap such as a polyolefin having a density of 1 or less has a problem that the flavor property is lowered with respect to a certain content. It was. For example, in a plastic bottle filled with shochu, there is a problem that the flavor is greatly reduced, and the flavor and the like of the shochu are impaired.

  The present inventors have found that such a decrease in flavor is caused by the anti-mold material used in the conveying path and the barrier property of the plastic cap. In other words, a package sealed with a plastic cap is used for transportation and storage by pallets, etc., and transportation and storage in a cardboard box in the process from manufacturing to sales. In general, an antifungal material such as trichlorophenol is used. This anti-mold material such as trichlorophenol prevents the generation of mold by reacting with microorganisms causing mold, but this reaction product migrates into the contents in the bottle through the plastic cap. As a result, the flavor of the contents is impaired. For example, trichlorophenol produces trichloroanisole (TCA), and the shift of the TCA significantly impairs the flavor of the shochu filled in the bottle.

  In order to improve the barrier against odor components derived from the above-mentioned mold prevention material, for example, it is conceivable to increase the thickness of the top plate of the plastic cap and the liner material layer as much as possible, Thickness cannot secure sufficient barrier properties, and it is necessary to increase the thickness to such an extent that it cannot be used in practice, and a significant increase in thickness leads to a significant increase in cost. . Furthermore, a means such as fitting a packing molded as a separate body from the plastic cap (which is considerably thicker than the liner material layer) into the inner surface of the top plate of the cap is also conceivable, but this also increases the cost.

  Accordingly, it is an object of the present invention to provide a plastic cap having improved shielding properties against odor components derived from fungicides such as trichloroanisole (TCA) without increasing the thickness and cost.

In a plastic cap comprising a top plate and a skirt-like side wall lowered from the periphery of the top plate,
At least the outer surface of the top plate is made of a polyester resin or polyurethane resin having a density of 1.10 g / cm ³ or more and a glass transition point (Tg) of 20 ° C. or more, and a coating resin layer having a thickness of 0.5 μm or more. A plastic cap is provided which is used as a cap of a plastic bottle for alcoholic beverages .

In the plastic cap of the present invention,
(1) The top plate is made of polyolefin,
(2) The resin forming the coating resin layer is a polyester resin,
Is preferred.

In the present invention, at least the top plate of the plastic cap is provided with a resin layer made of a resin having a high density (1.10 g / cm ³ or more) and a high glass transition point (20 ° C. or more). The odorous component generated by this, for example, trichloroanisole (TCA) or the like, is effectively suppressed from passing through the cap wall and transferred to the bottle contents, and the deterioration of the flavor properties of the bottle contents can be effectively avoided.

For example, trichlorophenol, which is a typical antifungal material, reacts with microorganisms causing mold under high temperature and high humidity to produce trichloroanisole (TCA). Such mold-proofing materials are used for pallets and cardboard used for transporting packages, and TCA generated as a result of microorganism capture passes through the plastic cap and migrates to the contents in the bottle. As a result, the flavor of the contents is impaired. In particular, the contents of alcoholic beverages such as shochu are sensitive to TCA, and the deterioration of flavor properties is remarkable. However, as will be apparent from Examples and Comparative Examples described later, when a packaging body in which the mouth of a polyethylene terephthalate bottle (PET bottle) is sealed with a plastic cap is stored in an atmosphere having a TCA concentration of 200 ppb and a temperature of 50 ° C. In the case of using a plastic cap (high density polyethylene cap, top plate thickness 2.3 mm) in which the above coating resin layer (hereinafter simply referred to as “resin layer”) is not formed (Comparative Example 1), In the case of using a plastic cap in which the resin layer is formed on the outer surface of the top plate according to the present invention (Example 1), the TCA concentration of the resin increased to 83 ppt after 4 weeks and 1326 ppt after 8 weeks. , Resin layer thickness 2.5 μm, resin density 1.28 g / cm ³ ), TCA concentration in the bottle after 4 weeks It will be understood that the barrier property against TCA is remarkably enhanced although it is 13 ppt and is about 600 ppt even after 8 weeks and the layer thickness is extremely thin. The effect of improving the barrier property against TCA is considered to be because the TCA gas permeation is physically blocked by forming a resin layer having a high density. Therefore, as shown in Comparative Example 2, when the resin layer is formed using an acrylic UV curable resin (resin density: 1.05 g / cm ³ ), the density is lower than the above range, and thus a barrier against TCA. It becomes inadequate.

  Thus, according to the present invention, since the resin layer is formed using a resin having a density equal to or higher than a certain value, the barrier property against TCA is remarkably improved even when the resin layer is extremely thin. It is not necessary to increase the thickness of the top plate of the cap for improvement, and it is not necessary to use a commonly used resin such as polyolefin as the cap material as it is, or to use a special resin or a special multilayer structure. Furthermore, there is no need to make the cap two-piece using packing or the like, and an increase in the cost of the cap can be avoided. Furthermore, the resin layer can be easily formed by coating with a solvent, which is extremely advantageous in terms of productivity.

[Resin layer]
In the present invention, a resin layer formed on the top plate of the plastic cap has a density of 1.10 g / cm ³ or more, is formed in particular by 1.16 g / cm ³ or more resins. That is, as described above, when a resin having a density lower than the above range is used, a sufficient barrier property against TCA cannot be obtained.

In the present invention, a polyester resin or a polyurethane resin is used as the resin having the above-described density, and an amorphous polyester resin is most preferable because a resin layer can be easily formed by coating with a solvent. is there.

Moreover, the barrier property against TCA or the like tends to be better as the glass transition point (Tg) is higher. Among the resins exemplified above, those having a glass transition point (Tg) of 20 ° C. or higher are used. That is, it is considered that the higher the glass transition point (Tg), the smaller the vibration of the molecules, and as a result, the barrier against gas components is improved.

In the present invention, as the thickness of the resin layer is thick, since the barrier property is increased with respect to malodor or off-flavor components TCA, etc., the thickness must be at 0.5μm or more, in particular 0.5 to the 2000μm The range is preferable, and by setting the above range, a sufficient barrier property against TCA or the like can be secured. More preferably, the thickness is in the range of 0.5 to 500 μm. By setting the thickness to this level, the resin layer can be easily formed by coating using an appropriate solvent.

[Plastic cap]
In the present invention, the structure of the plastic cap for forming the resin layer as described above is not particularly limited, but generally has a structure as shown in FIG.

  In FIG. 1, the plastic cap includes a top plate 1 and a skirt-like side wall 2 descending from the periphery of the top plate 1, and a screw 3 is formed on the inner surface of the skirt-like side wall 2. In other words, the plastic cap seals the bottle mouth by engaging the screw 3 with a screw provided on the outer surface of the mouth of the bottle. Further, an inner ring (not shown) can be provided on the inner surface of the top plate 1 at a distance from the skirt-shaped side wall, and the upper end of the mouth of the bottle is provided between the inner ring and the skirt-shaped side wall 2. It is also possible to adopt a structure in which the part is inserted.

  Further, although not shown, a tamper-proof band (TE band) may be provided at the lower end of the skirt-like side wall 2 via a breakable bridge. The TE band has an engagement piece or protrusion that engages with a jaw part or a ratchet claw formed on the bottle mouth part, and the cap fastened to the bottle mouth part is swung in the opening direction. In this case, the TE band piece or protrusion engages with the jaw part of the bottle mouth or the ratchet claw, so that the turning of the TE band in the opening direction is restricted. As a result, only the main body of the cap is raised, The band is cut off from the cap body when the bridge breaks. In other words, once the cap is opened, the TE band is cut off, so that the general consumer can recognize the fact of opening, and it is used for the purpose of quality assurance of contents and prevention of tampering. is there.

  The plastic cap as described above is manufactured by integral molding such as injection molding and compression molding using various thermoplastic resins, and has a multilayer structure provided with a layer of a gas barrier material such as an ethylene-vinyl alcohol copolymer. However, in the present invention, since an excellent gas barrier against TCA or the like can be obtained without using such a gas barrier material, the most widely used and inexpensive polyolefin-based resin, for example, low-, medium- or A single layer structure using high density polyethylene, linear low density polyethylene, polypropylene, or the like may be used. Further, it is not necessary to increase the thickness of the top plate 1 more than necessary in order to improve the barrier property against TCA or the like. For example, the thickness of the top plate 1 may be about 0.5 to 3.5 mm.

  In this invention, the resin layer 4 which consists of resin which has the above-mentioned high density is formed in the outer surface of the top plate 1 of the said cap, and, thereby, the barrier property with respect to malodorous or odorous components, such as TCA, improves notably. The resin layer 4 can be formed by any means, but as described above, it may be a thin layer. For example, an appropriate solvent is used, and the resin is dissolved or dispersed in the solvent. The resin layer 4 can be formed by preparing a liquid, applying it to a predetermined position of the cap by a coating means such as spin coating, screen printing, tampo printing, dip coating, and drying. The thickness of the resin layer 4 may be set to a desired value by appropriately adjusting the solid content concentration of the coating solution and adjusting the viscosity to an appropriate viscosity.

Also, the resin layer 4 as described above can be provided on the inner surface of the top plate 1 of the cap , and a liner material can be provided on the resin layer 4 on the inner surface, if necessary. The liner material is made of a flexible plastic, and when the cap is closed, the liner material is in close contact with the upper end of the mouth of the bottle to ensure a good sealing property. For example, low-density polyethylene, ionomer, ethylene-acetic acid It is formed of a highly flexible polymer material such as a vinyl copolymer, an ethylene-butene-1 copolymer, or a styrene-butadiene thermoplastic elastomer. Such a liner material is formed by dripping the melt of the liner material onto the inner surface of the top plate 1 of the cap, which has been molded in advance and on which the resin layer 4 is formed, and pushes the molten material on the inner surface of the top plate with a punch or the like.

The plastic cap of the present invention having the resin layer 4 described above on the outer surface of the top plate 1 has a high barrier effect against odor components such as TCA derived from the mold prevention material, and is used for plastic bottles filled with alcoholic beverages such as shochu. It is used as a cap, and can prevent a decrease in flavor due to an odor component derived from an antifungal material.

The present invention is further illustrated by the following examples, but the invention is not limited in any way by the following examples.
In the following examples, Examples 5 and 6 are reference examples outside the scope of the present invention.

(TCA transfer amount)
A commercially available 20 degree cautery was filled in a 2.7 L PET bottle, and a predetermined 36 mm diameter plastic cap was wound on. The PET bottles were placed upright in a desiccator adjusted to a TCA atmosphere concentration of 200 ppb and stored at an ambient temperature of 50 ° C. After 4 weeks and 8 weeks, the PET bottles were each removed from the desiccator, and 20 ml of hexane was added to 50 ml of the cautery of the content liquid, followed by extraction with shaking. The separated extract was injected into a gas chromatograph mass spectrometer (GC-MS QP5000) manufactured by Shimadzu Corporation, and the amount of TCA transferred was quantified. As the column, SPB-20 manufactured by SUPELCO was used.

[Example 1]
Polyester resin (Toyobo Co., Ltd., Byron GK880, resin density 1.28 g / cm ³ , glass transition point (Tg) 84 ° C.), ethyl acetate and methyl ethyl ketone (MEK) in a weight ratio of 65/35 The prepared mixed solvent was dissolved so that the solid content concentration was 20% by weight to obtain a coating liquid for resin layer formation.
After frame processing is applied to the outer surface of the top plate of a plastic cap (top plate thickness: 2.3 mm) produced by compression molding using high-density polyethylene, the above resin layer is produced using a manual tampo printer manufactured by Nippon Bunka Seiko Co., Ltd. A forming coating solution was applied. Thereafter, heat treatment was performed in a gas oven so that the peak temperature was 120 ° C. and the peak temperature holding time was 0 seconds, and a plastic cap having a coating layer with a film thickness of 2.5 μm was obtained.

[Example 2]
A plastic cap was obtained in the same manner as in Example 1 except that a polyester resin (manufactured by Toyobo Co., Ltd., Byron 200, resin density 1.26 g / cm ³ , Tg 67 ° C.) was used.

[Example 3]
Polyester resin (Toyobo Co., Ltd., Byron 245, resin density 1.36 g / cm ³ , Tg 60 ° C.) is dissolved in tetrahydrofuran (THF) to a solid content concentration of 10% by weight, and a coating solution for forming a resin layer A plastic cap was obtained in the same manner as in Example 1, except that

[Example 4]
A plastic cap was obtained in the same manner as in Example 1 except that a polyester resin (manufactured by Toyobo Co., Ltd., Byron GK810, resin density 1.17 g / cm ³ , Tg 46 ° C.) was used.

[Example 5]
A plastic cap was obtained in the same manner as in Example 1 except that a polyester resin (manufactured by Toyobo Co., Ltd., Byron 300, resin density 1.20 g / cm ³ , Tg 7 ° C.) was used.

[Example 6]
A plastic cap was obtained in the same manner as in Example 1 except that a polyester resin (manufactured by Toyobo Co., Ltd., Byron 550, resin density 1.17 g / cm ³ , Tg-15 ° C.) was used.

[Example 7]
After preparing a polyester resin (Toyobo Co., Ltd., Byron 200, resin density 1.26 g / cm ³ , Tg 67 ° C.) to 20% by weight as in Example 1, the crosslinking agent is used with respect to 100 parts by weight of the polyester resin. Except that 23 parts by weight of polyisocyanate (manufactured by Sumika Bayern Co., Ltd., Sumidur N3300) and 0.5 parts by weight of dibutyltin dilaurate as a catalyst are added to obtain a coating solution for forming a resin layer. A plastic cap was obtained in the same manner as in Example 1.

[Example 8]
A plastic cap was obtained in the same manner as in Example 7 except that a polyester resin (manufactured by Toyobo Co., Ltd., Byron 300, resin density 1.20 g / cm ³ , Tg 7 ° C.) was used.

[Example 9]
Polyester polyol (manufactured by Sumika Bayern Co., Ltd., Desmophen 670BA, 80% by weight butyl acetate solution) is diluted to 20% by weight with ethyl acetate, and polyisocyanate (Sumika Bayern) as a curing agent with respect to 100 parts by weight of polyester polyol. 48 parts by weight of Sumidur N3300 manufactured by Co., Ltd. and 0.5 parts by weight of dibutyltin dilaurate as a catalyst are added to form a coating solution for forming a polyurethane resin (resin density 1.11 g / cm ³ , Tg 15 ° C.). Got. Thereafter, a plastic cap was obtained in the same manner as in Example 1 except that heat treatment was performed so that the peak temperature was 130 ° C. and the peak temperature holding time was 0 seconds.

[Example 10]
Implemented except that the solid content concentration of the polyester resin (Toyobo Co., Ltd., Byron 200, resin density 1.26 g / cm ³ , Tg 67 ° C.) was 5% by weight and the coating layer thickness was 0.6 μm. A plastic cap was obtained in the same manner as in Example 1.

[Comparative Example 1]
A high density polyethylene plastic cap (top plate thickness 2.3 mm) produced by the same method as in Example 1 was used as an uncoated plastic cap.

[Comparative Example 2]
A coating liquid for forming an acrylic ultraviolet (UV) curable resin (resin density: 1.05 g / cm ³ , Tg of 100 ° C. or higher) comprising a polyester alkyd, an acrylate monomer, and a photopolymerization initiator is prepared, and the same method as in Example 1 It was applied with. UV irradiation was performed with a 120 W / cm metal halide lamp so that the UV curing condition was 250 J / cm ² to obtain a plastic cap having a coating layer with a thickness of 7.0 μm.

[Comparative Example 3]
Implemented except that the solid content concentration of the polyester resin (Toyobo Co., Ltd., Byron 200, resin density 1.26 g / cm ³ , Tg 67 ° C.) was 3% by weight and the coating layer thickness was 0.4 μm. A plastic cap was obtained in the same manner as in Example 1.
Table 1 shows the measurement results of the TCA barrier properties of the plastic caps obtained in the above Examples and Comparative Examples.

It is side sectional drawing which shows the typical shape of the plastic cap of this invention in which the resin layer which consists of a high-density resin was formed.

Explanation of symbols

1: Top plate 2: Skirt-shaped side wall 3: Screw 4: Resin layer

Claims (3)

In a plastic cap comprising a top plate and a skirt-like side wall lowered from the periphery of the top plate,
At least the outer surface of the top plate is made of a polyester resin or polyurethane resin having a density of 1.10 g / cm ³ or more and a glass transition point (Tg) of 20 ° C. or more, and a coating resin layer having a thickness of 0.5 μm or more. A plastic cap characterized by being used as a cap for a plastic bottle for alcoholic beverages . The plastic cap according to claim 1, wherein the top plate is made of polyolefin. The plastic cap according to claim 1 or 2, wherein the resin forming the coating resin layer is a polyester resin.

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