JP4382338B2 - Heat resistant cap - Google Patents

Description

【００４２】
【発明の効果】
本発明によれば、頂板部及び頂板部周縁から垂下するスカート部から成るキャップシェル、該キャップシェル頂板部内面に形成される密封用ライナー、及び該ライナーの表面中央部分に形成される被覆層からなる耐熱性キャップにおいて、前記ライナー及び被覆層は、キャップシェル内でライナー材及び被覆材を順次圧縮成形することにより形成されていると共に、前記ライナー材が耐熱性熱可塑性エラストマーから成り、前記被覆材が前記ライナー材と接着可能な結晶性熱可塑性樹脂から成ることにより、レトルト殺菌にも耐え得る耐熱性を有すると共に、内容物のフレーバー性や、ガスバリヤー性にも優れたキャップを提供できた。
【図面の簡単な説明】
【図１】本発明のキャップの一例を示す図であり、左半分が側断面図、右半分が側面図である。
【図２】本発明のキャップの一例の密封用ライナーの成形を説明するための図である。
【図３】本発明のキャップの一例の被覆層の成形を説明するための図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat-resistant cap, and more particularly to a cap having heat resistance that can withstand high-temperature sterilization such as retort sterilization, and excellent in flavor and moldability for contents.
[0002]
[Prior art]
In order to maintain the sealing reliability with the container, the cap has a sealing liner formed on the top plate of the cap. As such a sealing liner, the conventional cap has moderate elasticity and processability. However, the sealing material made of vinyl chloride plastisol has been widely used. However, it is desired to avoid the use of vinyl chloride from the viewpoint of environment and safety.
[0003]
From such a viewpoint, a thermoplastic elastomer having moderate elasticity and having excellent mechanical strength, wear resistance, and the like is used as a sealing liner material for a cap (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 3-182586
[Problems to be solved by the invention]
However, such thermoplastic elastomers are excellent in heat resistance but inferior in water vapor resistance, and when placed under high-temperature moist heat conditions such as retort sterilization, the odor components are easily adsorbed, and the flavor components of the content liquid are There is also a problem that the flavor property of the content liquid is lowered by the adsorption.
In addition, some thermoplastic elastomers have an odor per se, and the sealing liner is a part that directly touches the content liquid in the container. Therefore, the flavor of the thermoplastic elastomer is also transferred to the content liquid. There arises a problem that the performance is lowered.
Furthermore, due to the problem of storage stability of the contents of the container, not only the case where gas enters the inside from the contact interface between the container and the cap and affects the contents, but also the amount of gas entering through the inside of the liner material is reduced. However, since thermoplastic elastomers are inferior in gas barrier properties, it is also desired to maintain satisfactory gas barrier properties even in liner materials made of thermoplastic elastomers.
[0006]
Accordingly, an object of the present invention is to provide a heat-resistant cap that has heat resistance that can withstand retort sterilization, and that is excellent in flavor and gas barrier properties of the contents.
[0007]
[Means for Solving the Problems]
According to the present invention, from the cap shell comprising the top plate portion and the skirt portion depending from the periphery of the top plate portion, the sealing liner formed on the inner surface of the cap shell top plate portion, and the coating layer formed on the surface central portion of the liner In the heat resistant cap
The liner includes a seal surface that contacts the tip of the container mouth, an outer ring and an inner ring formed on the outer and inner sides of the seal surface, and an inner region defined by the inner ring. The heat-resistant thermoplastic elastomer is formed by compression molding, and the coating layer is formed by compression-molding polypropylene on the inner region of the liner .
[0008]
In the heat resistant cap of the present invention,
1. The coating layer has a thickness of 50 to 500 μm;
2. The thermoplastic elastomer constituting the liner material is one of a styrene elastomer, an olefin elastomer, and a urethane elastomer,
3. All the materials constituting the heat-resistant cap are made of materials that can be sterilized by retort,
Is preferred.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the cap of the present invention, the sealing liner formed on the inner surface of the top plate portion of the cap shell including the top plate portion and the skirt portion depending from the periphery of the top plate portion is in contact with the liner provided on the cap shell side and the content liquid of the liner. A two-layer structure of a coating layer provided so as to cover the part, the liner and the coating layer are formed by sequentially compression-molding the liner material and the coating material in a cap shell, and the liner material is heat resistant heat resistant. It is an important feature that it is made of a plastic elastomer and the covering material is made of a crystalline thermoplastic resin that can be bonded to the liner material.
[0010]
That is, in the present invention, the sealing liner formed in the cap shell has a two-layer configuration of a cap shell side liner and a coating layer that covers a portion of the liner in contact with the content liquid, and the liner is made of a heat resistant elastomer. By comprising, the sealing performance as a sealing liner and the opening performance can be improved, and compression molding in the cap shell is possible.
[0011]
In addition, by forming a coating layer made of a crystalline thermoplastic resin having excellent moisture resistance on the liner, most of the thermoplastic elastomer is not in direct contact with the contents, and the crystalline thermoplastic resin is a gas barrier. Because of its superior properties, it can prevent the odor component of the thermoplastic elastomer from migrating to the contents, and the thermoplastic elastomer does not adsorb the flavor components of the contents, providing excellent flavor. It becomes possible to make a cap. In addition, since the coating layer is made of a resin that can be bonded to the liner material, after the liner is first molded by an in-shell mold, a coating layer is similarly formed on the liner by an in-shell mold. The coating layer can be integrally provided on the liner without the necessity.
[0012]
In the present invention, the thermoplastic elastomer constituting the liner material preferably has an appropriate flexibility and a small permanent compression strain in order to have excellent sealing performance and openability over a long period of time. It is desirable that it is any one of an elastomer, an olefin elastomer, and a urethane elastomer.
[0013]
In the present invention, the resin constituting the coating layer is made of a crystalline thermoplastic resin that can be bonded to the liner material, and is excellent in heat resistance, odor barrier property, and water vapor resistance. The cap is necessary for having the above-mentioned characteristics, and examples of the resin having excellent heat resistance, odor barrier property, water vapor resistance, and the like include olefin-based resins and polyester resins. Polyethylene can be preferably used.
[0014]
The heat-resistant cap of the present invention has heat resistance particularly capable of withstanding retort sterilization, and all the materials constituting the cap are affected even when placed under high-temperature and humid-heat conditions such as retort sterilization. Consists of no material. Therefore, even if it is subjected to retort sterilization after capping, the sealing property that the liner should have, the opening property, and the odor barrier property that the coating layer should have do not deteriorate.
[0015]
The heat resistant cap of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a side view (right half) and a side cross-sectional view (left half) of an example of a heat resistant cap of the present invention, and FIG. 2 shows that a sealing liner in the heat resistant cap of the present invention is formed in a cap shell. FIG. 3 is a side sectional view for explaining a step of forming a coating layer on the sealing liner in the heat resistant cap of the present invention.
The heat-resistant cap generally indicated by 1 is generally composed of a top shell 3, a cap shell 2 comprising a skirt portion 4 depending from the periphery of the top plate 3, and a sealing liner provided on the inner surface of the top shell of the cap shell. 5 and a covering layer 6 covering the central portion of the sealing liner 5.
[0016]
In the specific example shown in FIG. 1, the inner surface of the skirt portion 4 of the cap shell 2 is formed with a screw portion 7 that is screwed with a container mouth portion (not shown), and the outer surface is gripped with a cap. A knurled groove 8 is formed to prevent slippage. An annular projection 9 is formed on the peripheral side of the inner surface of the top plate portion 3, and a sealing liner 5 is formed in an inner region defined by the annular projection 9.
A tamper evidence band 12 is integrally formed at the lower end 10 of the skirt portion of the cap shell through a weakened portion 11 that can be broken. The tamper evidence band 12 has an inner surface on the inner side when the cap is opened. A ratchet 13 for breaking the weakened portion 11 by engaging with a container mouth portion (not shown) is formed.
[0017]
The sealing liner 5 is formed with an outer ring 15 and an inner ring 16 on the outer side and the inner side of the sealing surface 14 that contacts the tip of the container mouth, respectively, thereby enhancing the sealing performance of the cap. The sealing liner 5 is also formed in the inner region 17 defined by the inner ring 16 as is clear from the liner forming step described later.
A coating layer 6 made of polypropylene or the like is formed on the inner region 17 of the sealing liner 5 to prevent the sealing liner 5 from coming into direct contact with the content liquid in the container. The deterioration of flavor properties due to the material is effectively prevented.
[0018]
In the present invention, it is an important feature that the sealing liner and the covering layer are formed by sequentially compression molding in the cap shell, and FIG. 2 shows the sealing liner by compression molding (in-shell molding) in the cap shell. It is a figure for demonstrating the process to form.
As shown in FIG. 2, the sealing liner 5 is formed by pressing a sealing liner material 20 made of thermoplastic elastomer supplied to the inner surface of the top plate portion of the cap shell 2 with a sealing liner forming embossing member 21. At the same time, the sealing liner 5 is bonded to the cap shell 2.
The sealing liner forming stamping member 21 has substantially the same outer diameter as the inner side of the annular projection 9 on the inner surface of the cap shell top plate, and the formed sealing liner includes the outer ring 15 and the inner ring described above. In order to have 16, recesses corresponding to these ring-shaped protrusions are formed on the pressing surface.
[0019]
FIG. 3 is a diagram for explaining a process of forming a coating layer by compression molding (in-shell molding) in the cap shell at the central portion (inner region 17) of the sealing liner.
As shown in FIG. 3, the coating material 30 made of olefin resin or the like supplied to the inner region 17 of the sealing liner is pressed with a coating layer forming embossing member 31 to form the coating layer 6 and seal it at the same time. The coating layer 6 is adhered to the liner 5 for use.
The coating layer forming stamp member 31 has substantially the same outer diameter as the inner region 17 of the sealing liner.
[0020]
(Cap shell)
In the present invention, as the cap shell, any conventionally known metal such as aluminum or synthetic resin such as polyethylene can be used.
In the case where the cap shell is made of metal, an in-shell mold of a sealing liner can be performed after an adhesive is previously provided on the cap shell.
[0021]
(Sealing liner)
The sealing liner used in the present invention is particularly preferably made of any one of a styrene elastomer, an olefin elastomer, and a urethane elastomer.
The styrene elastomer comprises a block copolymer comprising at least two polymer blocks A mainly derived from styrene monomers and at least two polymer block copolymers B mainly derived from conjugated diene compounds. A block copolymer obtained by hydrogenation is used. In this elastomer, a styrene-based unit becomes a hard segment, and a hydrogenated conjugated diene unit becomes a soft segment, and an elastomeric characteristic is exhibited.
[0022]
Examples of the styrenic monomer constituting the block copolymer include styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene, and among these, styrene is preferable.
Further, as the conjugated diene compound, for example, one or two or more kinds are selected from butanediene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc., among which butadiene, isoprene, and these The combination of is preferable.
The number average molecular weight of the block copolymer is preferably 500,000 or more, and the melt flow rate of a styrenic elastomer using this block copolymer (230 ° C., 2160 g load) is 0.1 to 5.0 g. It is preferably in the range of / 10 minutes.
[0023]
The olefin-based elastomer contains ethylene / α-olefin copolymer rubber and polyolefin resin as essential components, and at least one of them is partially crosslinked. In the olefin-based elastomer, the cross-linked portion becomes a hard segment, and the non-cross-linked portion becomes a soft segment and develops elastomeric characteristics.
[0024]
Examples of the ethylene / α-olefin copolymer rubber used as a raw material for the olefin elastomer include ethylene-propylene copolymer rubber, ethylene-propylene-nonconjugated diene ternary to multicomponent copolymer rubber, ethylene-butadiene copolymer rubber, ethylene-1 A substantially amorphous elastomer or a mixture thereof mainly composed of ethylene and an α-olefin having 3 to 14 carbon atoms, such as butene copolymer rubber and ethylene-1-butene-nonconjugated diene multicomponent copolymer rubber; . Examples of the non-conjugated diene include dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, dicyclopentadiene, methylene norbornene, and 5-ethylidene-2-norbornene.
[0025]
Among these copolymer rubbers, ethylene-propylene copolymer rubber and ethylene-propylene-nonconjugated diene copolymer rubber can be suitably used. The Mooney viscosity ML1 + 4 (100 ° C.) of the copolymer rubber is preferably in the range of 40 to 80, and the iodine value (unsaturation degree) of the copolymer rubber is preferably 30 or less.
[0026]
Examples of the polyolefin resin that is another raw material of the olefin elastomer include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl- Examples thereof include homopolymers of olefins such as 1-pentene, copolymers of two or more thereof, or copolymers of the above olefins with other polymerizable monomers of 15 mol% or less. Examples of other polymerizable monomers include vinyl acetate, methyl methacrylate, and ethyl acrylate.
The olefin elastomer of the present invention preferably has a melt flow rate (230 ° C., 10 kg load) in the range of 10 to 50 g / 10 min.
[0027]
The urethane elastomer is a block copolymer in which a polyurethane chain and a polyol chain are alternately linked. Preferably, the polyurethane elastomer is a heat-curing prepolymer composed of a polyisocyanate component (A) and a polyol component (B). It is a two-component type polyurethane elastomer obtained by making it.
As the isocyanate constituting the polyisocyanate component (A), aliphatic and / or alicyclic isocyanates can be suitably used. For example, hydrogenated aromatic isocyanate, hexamethylene diisocyanate (HDI), Examples include isophorone diisocyanate (IPDI) and lysine diisocyanate. Examples of the aromatic polyisocyanate include tolylene diisocyanate and diphenylethane diisocyanate.
Among these, HDI and / or IPDI can be preferably used.
The polyol component is specifically a high-molecular polyol, a low-molecular polyol or a mixture thereof, and a mixture of a high-molecular polyol and a low-molecular polyol is preferable from the viewpoint of easy selection of physical properties. 1 type, or 2 or more types of mixtures may be sufficient as a high molecular polyol and a low molecular polyol, respectively.
[0028]
Examples of the polymer polyol include polyols having a number average molecular weight of 500 or more, such as polypropylene glycol polyether polyol (PPG), polytetramethylene ether glycol (PTMG) and adipate polyester polyol, polycaprolactone polyester polyol, and polycarbonate. Based polyols and the like. From the viewpoint of eluate of polyurethane elastomer, PTMG and adipate polyester polyol are preferable. From the viewpoint of hydrolysis resistance, PTMG and PPG are more preferable.
[0029]
Examples of the low-molecular polyol include polyols having a number average molecular weight of less than 500, such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1, 4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, pentyl glycol, 1,8-octanediol, 1,9-nonanediol, diethylene glycol, cyclohexane -1,4-diol, cyclohexane-1,4-dimethanol, dimethylol heptane, dimer acid diol, trimethylol propane, glycerin, hexanetriol, quadrol, obtained by adding ethylene oxide or propylene oxide to these compounds Number average Compounds of less molecular weight 500, N, N, N ', N'- tetrakis (2-hydroxypropyl) ethylenediamine. The amount of the low-molecular polyol used is not particularly limited and is appropriately selected according to the hardness to be imparted to the target polyurethane elastomer. It is preferable to use in the range of 3 mol.
[0030]
Further, when a polyurethane elastomer is synthesized by reacting the polyisocyanate component (A) with the polyol component (B), the polyisocyanate component (A) is an active hydrogen possessed by the polyol component (B) and other components. It is preferable to use it in a ratio such that the number of moles of isocyanate groups per mole of active hydrogen atoms is 0.9 to 1.5 moles, based on the total amount of atoms, and a ratio of about 1.00 to 1.10 moles. More preferably, it is used.
As a method for synthesizing the polyurethane elastomer in the present invention, any of the known urethanization reaction techniques can be used, and either the prepolymer method or the one-shot method may be used.
[0031]
The sealing liner material of the present invention contains petroleum resin, various blocking agents, sealability improvers, heat stabilizers, antioxidants, ultraviolet absorbers, lubricants, crystal nucleating agents, colorants and the like as desired. It is also possible.
[0032]
(Coating layer)
The coating layer provided on the cap of the present invention is preferably made of a crystalline thermoplastic resin that can be bonded to the sealing liner, particularly those having excellent heat resistance, odor barrier properties, and water vapor resistance. Examples thereof include olefin resins such as polyethylene terephthalate, and polyester resins such as polyethylene terephthalate. Polypropylene is particularly preferable.
[0033]
When polypropylene is employed as the coating layer, it preferably has a melting point of 140 ° C. or higher. When the melting point is below the above range, the heat resistance becomes insufficient. In general, the melt flow rate (JIS K7210) is preferably in the range of 50 g / 10 min. If the melt flow rate is below the above range, the workability is poor, and if it exceeds the above range, the mechanical properties are reduced. Absent.
[0034]
The thickness of the coating layer is preferably in the range of 50 to 500 μm, particularly in the range of 100 to 250 μm. If the coating layer is thinner than the above range, sufficient odor barrier properties cannot be expressed and the flavor property is inferior. On the other hand, even if the coating layer is thicker than the above range, it becomes economically disadvantageous and easily peels off. .
Also for the coating layer, conventionally known heat stabilizers, antioxidants, and ultraviolet absorbers, if desired. Additives such as oxygen scavengers can also be blended.
[0035]
The heat-resistant cap of the present invention is formed by compression-molding the sealing liner and the coating layer in the cap shell. The melt of the sealing liner material and the coating material supplied in the cap shell is molded into the molding mold. It is manufactured by embossing and molding into a predetermined shape.
[0036]
【Example】
A 38 mm diameter resin cap was used as a cap shell, and a test cap was prepared using the liner material and the coating material shown below in the shell of the cap. 270 ml of distilled water was put into a glass bottle with a capacity of 300 ml, and the cap was sealed, followed by retorting at 125 ° C. for 30 minutes. The cap sample after the treatment and the evaluation of distilled water as the content liquid were evaluated according to the following items. The various elastomers used in the test and the various resins used as the coating layer are as follows. In the case of an amorphous thermoplastic resin, the test was not conducted because the adhesiveness with the liner was poor and molding was impossible.
[0037]
(1) Liner material
1) Styrene elastomer A AR800 (Aron Kasei Co., Ltd.)
2) PE modified grade of styrene elastomer B AR800 (Aron Kasei Co., Ltd.)
3) Olefin elastomer Miralastomer 6030N (Mitsui Chemicals)
4) Urethane elastomer Pelecene 2363 (manufactured by Dow Chemical Japan Co., Ltd.)
[0038]
(2) Polypropylene (PP)
1) PP-1 MA2 (Nippon Polychem Co., Ltd.)
2) PP-2 MC3B (Nippon Polychem Co., Ltd.)
3) PP-3 PV940M (manufactured by Sun Allomer Co., Ltd.)
4) PE-1 KM568A (manufactured by Nippon Polyolefin Co., Ltd.)
5) PE-2 4570 (Mitsui Chemicals)
6) PE-3 UJ580 (Nippon Polychem Co., Ltd.)
7) PET 2050 (Made by Unitika Ltd.)
[0039]
(3) Evaluation after retort
1) It was observed whether the edge part of each coating layer adhered to the center plane part of the liner material of the adhesive cap of the coating layer was not peeled off.
○: The edge of the coating layer is not peeled off.
X: The edge of a coating layer has peeled.
2) The elastomer used for the liner material of the functional cap has an odor peculiar to the elastomer. Open the cap after retorting and check the headspace for odor and taste.
○: Almost unpleasant odor is not confirmed. △: Slightly unpleasant odor. X: Obvious odor.
[0040]
From the result of Example 1, adhesion of the coating layer used for each cap was adhered without any problem. Moreover, a difference was confirmed in the presence / absence of the coating layer and the off-flavor odor of the content liquid depending on the thickness. This had a barrier property in the coating layer and prevented the transition of off-flavors and odors in the liner material.
[0041]
[Table 1]

[0042]
【The invention's effect】
According to the present invention, from the cap shell comprising the top plate portion and the skirt portion depending from the periphery of the top plate portion, the sealing liner formed on the inner surface of the cap shell top plate portion, and the coating layer formed on the surface central portion of the liner In the heat resistant cap, the liner and the coating layer are formed by sequentially compressing and molding the liner material and the coating material in a cap shell, and the liner material is made of a heat resistant thermoplastic elastomer, and the coating material Is made of a crystalline thermoplastic resin that can be bonded to the liner material, so that it has heat resistance that can withstand retort sterilization, and can provide a cap with excellent flavor and gas barrier properties.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of a cap according to the present invention, in which a left half is a side sectional view and a right half is a side view.
FIG. 2 is a view for explaining molding of a sealing liner as an example of the cap of the present invention.
FIG. 3 is a view for explaining molding of a cover layer as an example of the cap of the present invention.

Claims (4)

In a heat-resistant cap comprising a cap shell comprising a top plate portion and a skirt portion depending from the periphery of the top plate portion, a sealing liner formed on the inner surface of the cap shell top plate portion, and a coating layer formed on the surface central portion of the liner,
The liner includes a seal surface that contacts the tip of the container mouth, an outer ring and an inner ring formed on the outer and inner sides of the seal surface, and an inner region defined by the inner ring. A heat-resistant cap , wherein the heat-resistant thermoplastic elastomer is formed by compression molding, and the coating layer is formed by compression-molding polypropylene on the inner region of the liner .   The heat-resistant cap according to claim 1, wherein the coating layer has a thickness of 50 to 500 µm.   The heat-resistant cap according to claim 1 or 2, wherein the thermoplastic elastomer is any one of a styrene elastomer, an olefin elastomer, and a urethane elastomer. The heat-resistant cap according to any one of claims 1 to 3 , wherein the cap is made of a material that can be sterilized by retort.

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