KR20040097314A - Plastic barrier closure and method of fabrication - Google Patents

Abstract

The present invention is intended for use in bottles and the like, comprising: (1) a body having at least one concentric sealing member having a top wall, sidewalls, securing means and seals, the seal extending from the top wall, and (2) A plastic blocking plug having a blocking layer. The barrier layer can be formed by (1) placing molten material of the barrier polymer in the preformed lid body and molding it in place by mechanical means, or (2) forming a barrier layer from the barrier polymer and inserting it into the preformed lid body. May be incorporated into the top wall.

Description

PLASTIC BARRIER CLOSURE AND METHOD OF FABRICATION}

Plastic stoppers for packaging containers containing glass or plastic bottles have long been used commercially. The plastic lid, the most common example, is screwed inside so that the plastic lid can be screwed onto the neck of a PET bottle used to package various beverages containing carbonated beverages. Lids most common for carbonated beverages generally include an outer shell molded from polypropylene with a liner material made of ethylene vinyl acetate polymer compound. The outer shell is manufactured by injection molding or compression molding. The liner is provided in two ways: 1) a "pick and place" method in which a disc of preformed material is mechanically placed into the skin and 2) a small amount of molten material is placed on the skin and is removed by the plunger. It is installed using any of the "in-shell moldings" that are molded in position. The lid liner functions as a mechanical gasket or seal against leakage of carbon dioxide gas from the lid. These lids are referred to as "two piece" lids.

More recently, other types of lid designs have been introduced to the market. Referred to as "one-piece" or "linerless" lids, these are injection molded or compression molded lids made of homopolymer, most commonly HDPE. Examples of such closures are described in US Pat. Nos. 3,948,405, 4,526,284, 4,739,893 and 5,743,420, which are incorporated herein by reference. These lids can provide a suitable mechanical seal for CO ₂ leakage from, for example, carbonated beverages, via a suitable combination of geometric design and materials.

Although the lid designs described above can provide a good mechanical seal against gas leaks, these designs are ineffective in preventing gas penetration through the walls of the lid because the commonly used polyolefin polymers have relatively poor gas barrier properties. to be. For many packaging applications, better barriers to gas penetration are required.

Many approaches to plastic closures with improved barriers have been described in the prior art. One approach is to replace the liner used in the two-piece cap with a liner formed of barrier material. European Patent No. 6640 discloses the use of a multilayer structure in which at least one layer provides a barrier to gas penetration and at least one other layer functions as a mechanical seal layer. Japanese Patent No. 07137754 describes a stopper including a multilayer liner having a barrier layer and a seal layer with a stopper body molded on the liner. EP 926078 describes a sealing liner consisting of alternating layers of substrate and barrier material. In both European Patent No. 6340 and 926078, the liner functions both as a mechanical seal against gas leakage and as a barrier against gas penetration. Another approach to blocking plugs described in European Patent No. 233414 is a conventional plastic lid (virtually one-piece or two-piece) with a coating of "vapor impermeable material" that is cured to form a solid and is permanently attached to the lid. ) Is to cover.

Another concept for barrier lids is to manufacture the lid of a linerless design, preferably with a material that exhibits better barrier properties than HDPE. However, most barrier polymers tend to be hard and hard, making it difficult to achieve good mechanical seal against gas leakage.

The present invention relates to plastic stoppers (or lids) for containers such as glass bottles or PET bottles. The stopper may also provide a barrier that prevents the delivery of gases such as carbon dioxide or oxygen and may reduce the propensity to "scalp" the fragrance component from the packaged product. It will also be described how to make such a stopper.

1 is a vertical sectional view of a closure according to the invention applied to the neck of a container.

Figure 2 is a vertical sectional view of the closure according to the invention with the inner concentric ring installed on a container providing a mechanical seal.

Figure 3 is a vertical sectional view of the stopper according to the invention installed on a container in which the outer concentric ring provides a mechanical seal and the blocking layer functions as a protruding stop.

FIG. 4 is a vertical sectional view of the closure according to the invention installed on a container having a configuration different from FIG. 3 in which the outer concentric ring provides a mechanical seal and the blocking layer functions as a protruding stop. FIG.

The present invention provides a plastic stopper (or lid) for a container, in particular a container having a threaded neck on the outside such as a bottle or the like that can be filled or emptied through the neck. The neck of the container or the opening of the container is a tubular member whose one end is connected to the container and the opposite other end (top corner or rim) is opened. The rim has an inner edge and an outer edge. The tubular member has an inner side and an outer side. Preferably, on the outer side there is a screw extending between the top edge and one position between the bottom and top edges of the member. Preferably, the closure is secured to the bottle (or screwed to the bottle) as the screw on the inner side of the stopper engages with the screw on the outer side of the bottle opening. Other means for securing the cap to the bottle may be used.

The stopper exhibits good barrier to gas delivery and reduces the tendency to absorb fragrance components from the packaged product. The stopper includes a body and a barrier layer.

The body,

a. A disc shaped top wall having an inner surface arranged to contact or nearly contact the rim of the container neck when fastened on the neck,

b. A cylindrical sidewall attached to and extending from the top wall,

c. Means for securing the neck and the body, preferably comprising internal screws of cylindrical sidewalls which engage with corresponding screws on the outer surface of the neck;

d. A seal disposed to provide a good mechanical seal against gas leakage when the stopper is installed on the container.

The seal is attached to the inner side of the upper wall and extends therefrom and is concentric with the cylindrical side and continuously with the neck of the container (top of the rim, inner or outer edge of the rim, or sidewall of the neck) when the body engages with the neck. At least one sealing member disposed to contact.

As an alternative, the seal

Iii. An outer sealing member disposed between the inner side of the cylindrical sidewall and the outer edge of the bottle opening such that it is attached to and extends from the inner side of the upper wall and in continuous contact with the upper outer edge of the rim of the container neck when the body engages the neck; ,

Ii. It may comprise an inner sealing member concentric with the outer sealing member and extending from the inner side of the upper wall of the body to be in continuous contact with the inner edge of the rim when the body is engaged with the neck.

The body is made of molded plastic, most preferably HDFE.

The barrier layer incorporated into the upper wall of the body is selected from materials known to provide good barrier to gas infiltration and to lower the propensity to absorb fragrance components from the packaged product. The barrier material can be any of many barrier polymers, including EVOH, nylon, and polyesters (including mixtures of 2GTs, 3GTs, and 2GTs and 3GT polyesters). Amorphous nylon or 3GT polyester is preferred. The barrier layer may be metallic such as aluminum.

Another embodiment includes a body having a seal having one sealing member attached to and extending from the inner side of the top wall and disposed to be in continuous contact with the outer edge of the container when the body is fastened to the neck of the container. When only the outer sealing member is used as the seal, the barrier material preferably contacts the rim of the container when the stopper is fastened to the container neck.

The barrier layer is incorporated into the body of the cap by one of two methods,

a. A method in which a melt of barrier polymer is placed in a preformed cap body and molded in place by mechanical means, referred to as "in-shell molding",

b. It is a method called "pick and place", in which the barrier layer is molded in a separate step and then installed into the preformed cap body.

The present invention provides a generally cylindrical plastic stopper for sealing the open end of the container neck (or lid) in a manner that provides excellent barrier to gas delivery and reduces the propensity to absorb fragrance components from the product packaged in the sealed container. To provide. Such stoppers are particularly useful as lids on glass bottles, PET bottles, such as those used in carbonated beverages, beer and other beverages. The stopper may optionally comprise a guarantee ring or a quality proof strip. The stopper comprises a bottle cap shaped body (ie, generally having a discoid top wall and having a cylindrical or tubular side member substantially perpendicular to and extending from the top wall) and a barrier layer incorporated into the top wall of the stopper. .

As may be more clearly understood with reference to the drawings, which are part of the present disclosure, the body of the closure has a means for securing the closure to the container and a means for providing a mechanical seal when the closure is secured to the container.

The means for securing the stopper is typically an internal screw which is encased with an external screw on the neck of the container as shown in FIG. Although the closure of the present invention is described as using a screw fastening with the container neck, practical advantages can be realized using other fastening means, such as when crowned or snap-on type stoppers are used. Should be understood.

The means for providing a mechanical seal preferably comprises one or more sealing members attached to and extending from the inner top of the stopper such that the stopper is contacted with the container neck when the stopper is secured to the container.

1 and 2 show a closure according to the invention applied to the neck of a container. The body 1 of stopper comprises an upper wall 2, a side wall 3 with a screw therein and a seal 4. The seal may consist of an inner concentric ring 4a, an outer concentric ring 4b, or both. The seal extends downward from the inner surface of the top wall and is arranged to engage the neck of the container to provide a good mechanical seal against the leakage of gas when the stopper is screwed into the bottle. The body 1 of the stopper may have a different configuration. The prior art includes many designs for such plastic closures in which one section or sections of the closure body are arranged to engage the neck of the container to realize a good mechanical seal against gas leakage. The seal may be arranged to engage the neck of the container on the rim 7, on the inner wall 8 or on the outer wall 9. This type of plug is called a "piece" or "linerless".

The body comprises polyolefins such as high-density polyethylene (HDPE), low density polyethylene (LDPE) and polypropylene (PP), nylon, polyvinylchloride, polycarbonate, polystyrene, and polyester It can be made of many plastic materials. Although thermoset polymers may be used, thermoplastic polymers are generally preferred. In many packaging applications, and especially for packaging carbonated beverages, HDPE is preferred as a component of the body. HEPE exhibits a combined property of several mechanical properties suitable for producing effective mechanical seals on container rims (particularly in terms of strain coefficient and hardness). In packaging applications involving hot-fill or sterilization depending on pressure and temperature, HDPE cannot provide adequate heat resistance as the body material. In such applications, materials such as polypropylene or nylon that exhibit higher heat resistance than HDPE may be desirable. The body can be produced using common thermoplastic processing methods such as compression molding or injection molding.

Stopper layer 5 is a mixture of amorphous nylon, semicrystalline nylon, ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC), and 2GT, 3GT, 2GT and 3GT polyester It can be made of many common barrier materials including polyester (PE) and polyacrylonitrile. The barrier layer may be made of a metal such as aluminum, but plastic barriers are generally preferred. The blocking layer of the stopper functions to prevent penetration of gases such as carbon dioxide and oxygen through the stopper. It may also reduce the propensity to absorb or “scalp” the fragrance component from the packaged product or convey an undesirable component to the product. Preferred materials for the barrier layer are amorphous nylons such as Selar from Dupont de Nemours and Company. Among the common barrier materials for liquid packaging, amorphous nylon provides the best combination of gas barrier properties and non-cutting performance. Another preferred material is 3GT, which provides good barrier properties and ease of handling. In particular, 3GT can be melted and treated at lower temperatures than other common barrier polymers.

The barrier layer can be incorporated into the closure body by a variety of methods, including the following methods.

1) The melt of barrier material is placed on the inner side of the upper wall of the preformed body and molded in place by the movable plugger to form the finished barrier layer. This process is called "in-shell molding". The molten material may be a conventional polymer melt or the molten material may be foamed using chemical or physical blowing agents. The amount of barrier material disposed is controlled so that the finished dimensions of the barrier layer can be kept within available limits. The face of the forming plunger is designed to give the desired face to the exposed face of the barrier layer.

In Fig. 2, the barrier layer 5 is flat. In Figures 3 and 4, the barrier layer 5 is shaped to provide a raised area that acts as a stop of the container rim 7. The plunger diameter is slightly smaller than the minimum diameter of the innermost seal ring of the body such that there is minimal play between the plunger and seal ring when the plunger presses the molten barrier into the body. Facilities using this in-shell forming process are available from companies including Sacmi and Overurg Engineering AG. The barrier layer 5 is retained in the body 1 of the closure by direct attachment to the body or by mechanical retention or both. In order to obtain a mechanical retaining portion, the closure body 1 preferably has a seal ring such that the outer diameter of the barrier layer 5 is somewhat larger than the inner minimum inner diameter of the seal ring 4b, as shown in FIGS. 3 and 4. The undercut 6 is formed in the root part of (4b).

2) The barrier layer 5 is formed in a separate process and installed in the preformed body 1 by mechanical means to produce a finished plug. This process is called "pick and place." The blocking layer 5 is retained in the body 1 by mechanical retention.

As shown in Figs. 3 and 4, the undercut 6 is formed in the root portion of the seal ring 4b in the body 1, thereby forcing an interference between the preformed blocking layer 5 and the body 1. To form. The preformed barrier layer must have sufficient flexibility to not cause cracks and to be damaged in the installation process. This method of installation is particularly suitable for metallic barriers and thermosetting plastic barriers but can also be used when the barrier layer is formed of a thermoplastic material.

Another way to prepare a plastic shutoff lid according to this design is to use a coextrusion injection molding process. In this process two extruders are used to produce the molten material, one being the extruder for the body material and the second extruder for the barrier material. The melt is introduced simultaneously or continuously into the mold cavity to form the finished plastic lid. The equipment and tools used in this process are more complex and expensive than the equipment and tools used in the "in-shell shaping" process or the "pick and place" process.

The advantage of the present invention is most pronounced when the gas barrier properties of the barrier layer material are at least one order, preferably at least two orders of magnitude greater than that of the body material. For example, one preferred embodiment of the present invention includes an HDPE body and an amorphous nylon barrier layer, wherein the amorphous nylon exhibits a CO ₂ barrier that is about 100 times greater than HDPE.

In one embodiment of the invention, as shown in FIG. 2, the seal in the body 1 is arranged to engage the inner edge 7a of the rim of the neck of the container when the plug is installed in the container. Only the inner concentric seal member 4a extending downwards. As an alternative, the inner concentric seal ring 4a may be arranged to engage the inner wall 8 of the neck of the container. The inner seal member 4a provides a mechanical seal against gas leakage and the barrier layer 5 provides a primary barrier against gas penetration.

In a preferred embodiment of the invention, as shown in Figures 3 and 4, the seal in the body 1 is arranged to engage the outer edge 7b of the rim of the neck of the container when the lid is screwed onto the container. It includes only the outer concentric sealing member 4b extending downward from the upper wall 2 to be made. As an alternative, the outer concentric sealing member 4b may be arranged to engage the outer wall 9 of the neck of the container. The barrier layer 5 is incorporated into the body 10 of the lid, preferably by screwing the neck to the neck using a prescribed installation torque, typically 14 to 18 inch-pounds, preferably for a 28 mm lid. It is designed to contact the rim upper edge 7 (FIG. 3) or the rim inner edge 7 a (FIG. 4) of the bottle when fixed on the neck. The design of the barrier layer may have a bead 7c (Fig. 3) in contact with the rim upper edge 7 or it may have a taper (Fig. 4) such that the barrier is only in contact with the inner edge 7a. In this embodiment, the barrier layer 5 functions as a protruding stop when the plug is installed on the container. The outer seal member 4b of the body provides a primary mechanical seal against gas leakage and the barrier layer 5 provides a secondary mechanical seal and functions as a primary barrier to gas penetration. In the present preferred embodiment, when the stopper is properly installed on the container, the packaged product is not in direct contact with the body material, and optimum gas barrier and non-cutting performance is achieved.

The materials used to make both the body and the barrier liner can optionally be changed to other materials commonly used in the lid and closure industries. These modifications may include pigments, slip agents, oxygen scavengers, among others.

Although a common use of the present invention is closure for PET bottles, these closures can be used for all kinds of containers with generally cylindrical necks, such as bottles or cans made of glass, plastic or metal.

Claims (11)

A closure comprising a body and a barrier layer for a container having an outer wall, a cylindrical neck having an inner wall and an open rim with an inner edge and an outer edge, a. The body, (Iii) a disc shaped top wall having an inner surface arranged to contact or nearly contact the rim of the container neck when fastened onto the container neck, (Ii) a cylindrical sidewall having an inner side that is in contact with or nearly contacts the rim of the container neck when fastened to a neck that is attached to and extends substantially perpendicularly from the top wall; (Iii) means for securing the container neck and body, (Iii) a seal comprising at least one sealing member attached to and extending from the inner side of the upper wall and concentric with the cylindrical side and arranged to be in continuous contact with the container neck when the body is engaged with the container neck; , b. The stopper layer is incorporated into the top wall of the body and is made of a barrier material selected to provide a barrier to gas penetration and absorption of the fragrance component of the container contents when the body is secured to the neck of the container. The method of claim 1 wherein the seal is a. An outer sealing member attached to and extending from the inner side of the upper wall and concentric with the cylindrical side and arranged to be in continuous contact with the outer upper edge of the container neck when the body is engaged with the container neck, b. A closure comprising an inner sealing member attached to an inner side of an upper wall of the body and extending therefrom and concentric with the outer sealing member and disposed to be in continuous contact with the inner edge of the container neck when the body engages with the container neck. A closure according to claim 1 or 2, wherein the securing means comprises an internal thread of cylindrical sidewalls which engages with a corresponding thread on the outer side of the container neck. The seal of claim 1, wherein the seal comprises an outer sealing member disposed to engage the outer edge or outer wall of the neck of the container, the barrier layer being formed with the upper edge or inner edge of the neck of the container when the closure is installed on the container. A stopper arranged to be fastened. A stopper according to claim 1 or 2, wherein the body is made of a thermoplastic material selected from the group consisting of polyolefins, nylons, polyvinyl chlorides, polycarbonates, polystyrenes and polyesters. 6. The closure of claim 5, wherein the polyolefin is selected from the group consisting of high density polyethylene, low density polyethylene, linear low density polyethylene, and polypropylene. The closure of claim 1, wherein the barrier layer is incorporated into the top wall of the closure body using an in-shell molding process or a pick and place process. The barrier layer of claim 1 or 2, wherein the barrier layer is made of a material selected from the group consisting of amorphous nylon, semicrystalline nylon, ethylene vinyl alcohol, polyvinylidene chloride, polyester, and polyacrylonitrile. stopper. A stopper according to claim 5, wherein the body is made of high density polyethylene. The stopper of claim 8, wherein the barrier layer is made of amorphous nylon or 3GT polyester. The closure of claim 1, wherein the container is a PET bottle.