Patent Application
20150166223
The present invention relates to a cork stopper coated with a resin layer for plugging the mouth portion of a container for beverages like whisky or wine.
A cork stopper coated with a resin (rubber) layer integrated at one end with a flange portion doubling as a handle is widely used as a cork stopper for plugging the mouth portion of a container for beverages like whisky or wine, referring to Patent Literature 1 to 4. A cork stopper body of the cork stopper coated with a resin layer is formed in a columnar shape by the compression molding of a cork granule and a binder resin, or formed in a columnar shape by boring natural cork bark. A coating layer of resin is formed for preventing a corky smell from diffusing into the beverage in the container, preventing cork dust from falling into the container, preventing a color change on the cork surface caused by the invasion of beverage into a cork layer, and the like. A stable openability of the cork stopper regardless of a storage condition and a usage condition of the container is demanded when the cork stopper is coated with a layer made of resin. In the Patent Literature, the friction coefficient of the surface of the coated layer is appropriately determined by executing a silicone treatment or a roughening treatment on the coated layer surface.
In a production method of a cork stopper in Patent Literature 5 proposed by the applicant of the present application, a cork granule is pressed in a direction orthogonal to the longitudinal direction, i.e. the axial direction, of the columnar body, namely in the centripetal direction when the columnar cork stopper is molded under compression with binder resin. The cork stopper obtained by such a compression molding, having a coating layer of resin, has excellent flexibility in the diametrical direction and the sealing ability is improved by its conformability to the container mouth. Thereby, good features such as an easy openability and the prevention of damage at the time of opening are obtained.
PTL 1 JP-S63-147456-U1
PTL 2 WO2004/020300
PTL 3 JP-2004-231244-A
PTL 4 WO2011/155515
PTL 5 JP-2010-099909-A
In the case of the above-mentioned cork stopper coated with a resin layer, the friction coefficient is optimized for improving the openability of the cork stopper by a silicone treatment or a roughening treatment on the surface of the coating layer. However, such treatment for optimizing the friction of coefficient adds to production procedures and increases the production cost. When the stress of the cork changes, the openability of the cork stopper is not kept stable even if the friction coefficient is controlled. It is difficult to simultaneously achieve improvement in the openability and prevention of popping of the cork stopper. In addition, when the cork stopper coated with a resin layer is used for a container for beverages such as whisky or wine, the moisture content ratio of the core portion varies from two to six percent by weight, depending on the change of seasons. When the moisture content ratio is low, the compression stress of the cork stopper pressed into the mouth of the beverage container becomes large, thereby deteriorating openability. Therefore, it is desired to maintain a good openability in which the variation of the compression stress is less regardless of the change of seasons. As a result of verification by the inventors of the present application, the cork stopper disclosed in Patent Literature 5 is superior in the stability of the stress at the time of closing the container mouth with the cork stopper molded under pressure along the axial direction.
The present invention is proposed in view of the above-mentioned problems and has an object to provide a new cork stopper coated with a resin layer having a stable openability while keeping the unique sealing ability of the cork stopper. In addition, the inventors endeavored to apply their insights from the aforementioned results to a cork stopper coated with a resin layer, and as a result of numerous considerations, a cork stopper coated with a resin layer which has a stable openability and hardly pops out was easily obtained. Thus, the object of the present invention is to provide such a new cork stopper in view of the verified results.
In one embodiment of the present invention, the cork stopper coated with a resin layer comprises a columnar cork stopper body formed by a compression molding of a cork granule with a binder resin and a resin coating layer covering an outer circumferential surface of the cork stopper from an end side to another end of the cork stopper body along an axial direction. The cork stopper body and the resin coating layer constitute a core portion, and the core portion, when being pressed in a hollow tubular portion with a tightening allowance of 1.5 mm, experiences a compression stress of 100N to 300N in the case of a moisture content ratio of the core portion being 6 percent by weight and experiences a compression stress 100N to 150N smaller than that in the case of a moisture content ratio of the core portion being 2 percent by weight.
Generally, when the cork stopper coated with a resin layer is used for a container for beverages such as whisky or wine, the moisture content ratio of the core portion varies from two to six percent by weight, depending on the change of seasons. When the moisture content ratio is low, the compression stress of the cork stopper pressed into the mouth of the beverage container becomes large, thereby deteriorating openability. In the case of a cork stopper coated with a resin layer of an embodiment of the present invention, the compression stress is as small as 100N to 300N when the moisture content ratio of the core portion is 6 percent by weight, and the difference from the case when the moisture content ratio of the core portion is 2 percent by weight is as small as 100 to 150N. Therefore, openability is kept stable regardless of the change of seasons. If the compression stress at a moisture content ratio of 6 percent by weight in the core portion is smaller than 100N, the sealing ability becomes deteriorated. If the compression stress at a moisture content ratio of 6 percent by weight in the core portion is larger than 300N, the compression stress becomes large when the moisture content ratio changes to 2 percent by weight, thereby deteriorating the openability.
In the cork stopper coated with a resin layer as mentioned above, the cork stopper body can be formed by a compression molding executed in a centrifugal direction. In the cork stopper coated with a resin layer in an embodiment of the present invention, the cork stopper body is molded under compression in the centripetal direction, thereby having superior flexibility in the diametrical direction. When such a cork stopper coated with a resin layer is pressed to plug the container mouth portion, the cork stopper elastically contacts the inside of the mouth portion with flexibility and is elastically compressed with the resin coating layer interposed between the cork stopper and the inside of the mouth portion, thereby obtaining a stable sealing ability. The strength in the longitudinal direction (in the axial direction) of the cork stopper body, coupled with the binding force of the binder resin, becomes large, thereby preventing breakage of the cork stopper at the time of opening or closing.
In the cork stopper coated with a resin layer as mentioned above, the cork stopper body can have an attachment hole configured to attach a flange portion, the attachment hole extending from the end side to the other end side of the cork stopper body along an axial direction.
In the cork stopper of an embodiment, the flange portion is attached to the attachment hole and the cork stopper is easily closed or opened using the flange portion as a handle.
In such a case, the cork stopper coated with a resin layer can comprise an expanding portion with a diameter larger than an outer diameter of another portion of the core portion, the expanding portion extending from a region corresponding to a bottom of the attachment hole to the other end of the cork stopper.
In such a configuration, the expanding portion prevents the stopper from popping out.
Further, the expanding portion can be formed by heating the core portion.
When the core portion is heated, the cork stopper body thermally expands. In an embodiment of the present invention, the core portion from the region corresponding to the bottom of the attachment hole to the other end is solid and the cork stopper body is molded under compression in the centripetal direction, thus thermal expansion enlarges the diameter of the core portion. Therefore, the expanding portion is easily formed by heating.
In the cork stopper coated with a resin layer as mentioned above, the resin coating layer can be made of a polyethylene terephthalate. When the cork stopper coated with a resin layer is used for a beverage container, the resin coating layer contacts liquid. The resin coating layer is made of a polyethylene terephthalate with a high barrier property, so that a corky smell is prevented from diffusing into the beverage in the container. Polyethylene terephthalate is harmless and hygienic, thereby being suitable for a resin layer of a cork stopper for beverages.
In the cork stopper coated with a resin layer as mentioned above, the resin of the coating layer can include a lubricant.
In the above-mentioned embodiment, the resin of the coating layer includes a lubricant, so that the friction coefficient of the coating layer surface is easily controlled and a stable openability is obtained.
The present invention is able to provide a cork stopper coated with a resin layer with a stable openability while keeping the unique sealing ability of the cork stopper.
The embodiments of the present invention are explained referring to the attached drawings.
The flange portion 5 is made of glass and comprises a disk-like flange body 50 and a columnar projecting portion 51 projecting downward from the center of the flange body 50. The projecting portion 51 is pressed in the attachment hole 20 of the cork stopper body 2 in such a manner that the lower surface of the flange body 50 abuts the upper surface of the cork stopper body 2. The abutting surface and the pressed surface are coated with an adhesive agent, thus the cork stopper body 2 and the flange portion 5 are integrally fixed. A washer 6 made of polyethylene is fitted around the outer circumference of the cork stopper body 2 so as to contact the lower surface of the flange body 50. A part of the cork stopper body 2 to which the washer 6 is provided is not coated with the resin coating layer 3. The washer 6 is provided between an upper open edge portion 70a of a mouth portion 70 and the lower surface of the flange body 50, preventing direct contact of the open edge portion 70a and the lower surface of the flange body 50, when the core portion 4 of the stopper coated with a resin layer of this embodiment is pressed into the mouth portion 70 (hollow tubular portion) of a container 7 for whisky (two-dotted line) for closing the mouth portion 70. In this specification the term “close” means to plug the mouth portion 70 of the container 7 with the cork stopper coated with a resin layer 1. The container 7 made of glass does not contact the flange portion 5 made of glass and a consumer is able to plug the mouth portion without causing unpleasantness.
In the explanation referring to
The production method of a cork stopper coated with a resin layer 1 is explained further referring to
At step S4, the resin coating layer 3 is formed on the outer circumferential surface (referred to as the circumferential surface hereinafter) of the cork stopper body 2 from the end 2a side to the other end 2b. For providing the resin coating layer 3, a urethane adhesive agent is applied on the circumferential surface of the cork stopper body 2. Then, the circumferential surface of the cork stopper body 2 is covered with a heated polyethylene terephthalate film and then is pressed into a mold. The polyethylene terephthalate film in an extended condition is thermally attached on the circumferential surface of the cork stopper body 2. Thus, the resin coating layer 3 is formed by a polyethylene terephthalate bonded on the entire circumferential surface of the cork stopper body 2 and the core portion 4 is formed with the cork stopper body 2 and the resin coated layer 3. Polyethylene terephthalate is preferably used for the resin of the resin coating layer for a beverage container because polyethylene terephthalate is harmless, hygienic and excellent in preventing the diffusion of a corky smell into the beverage in the container. However, the resin is not limited to polyethylene terephthalate. Polyethylene, nylon, polybutylene terephthalate, ethylene-vinyl acetate copolymer, or the like can be selectively used depending on the usage. The resin of the resin coating layer 3 desirably includes a lubricant. The lubricant can be a resin lubricant such as a spherical silicone resin and a spherical polyethylene resin, or an inorganic lubricant such as silica, clay and talc.
At step S5, silicone is applied and heated on the circumferential surface (zone 1 in
At step S5, heating is executed after silicone is applied; however, heating can be executed without applying silicone.
During the manufacturing of the resin cork stopper 1, a tightening allowance is generally required for the cork stopper of a container for beverages such as whisky, so that an outer diameter D1 of a columnar portion 40 of the core portion 4 other than the expanding portion 41 is set 1.5 mm larger than the smallest inner diameter of an inner diametrical face 70b of the mouth portion 70 of the container 7. Namely, when the cork stopper coated with a resin layer 1 is pressed into the mouth portion 70 of the container 7 shown in
The cork stopper coated with a resin layer produced as mentioned above and the conventional cork stopper coated with a resin layer disclosed in Patent Literatures 1, 2 and 4 include moisture of 2.0 percent by weight (moisture content ratio) at the time of production and the moisture content ratio changes from 2.0 to 6.0 percent by weight depending on the conditions thereafter. When the moisture content ratio changes, the compression stress when the cork stopper plugs the mouth portion of the container by being pressed therein also changes.
As shown in
Several examinations were executed for moisture content ratios in the range of 2.0 to 6.0 percent by weight. It was found that, in view of sealing ability, the openability and popping of the cork stopper, in the case of pressing the core portion into the hollow tubular portion with a tightening allowance of 1.5 mm, the compression stress should be 100N to 300N when the moisture content ratio of the core portion 4 is 6 percent by weight and should be 100N to 150N smaller than that when the moisture content ratio of the core portion is 2 percent by weight. It was also found that the excellent features of the cork stopper coated with a resin layer of the embodiment of the present invention were based on the fact that the cork stopper body was formed by a compression molding in the centripetal direction, and the friction coefficient of the surface of the core portion was easily controlled, unlike those of a conventional cork stopper coated with a resin layer.
When the cork stopper coated with a resin layer 1 plugs the container 7, a part of the expanding portion 41, as shown in
The expanding portion 41 extends from the region corresponding to the start point of 20b of the attachment hole 20 to the other end 2b of the core portion 4, namely the entire area of the zone Z1. Thus, the largest outer diameter D3 of the expanding portion 41 becomes larger than the outer diameter D1 of the columnar portion 40. In addition, the relation of the diameters in relation to the outer diameter D4 corresponding to the deepest portion of the bottom 20a of the attachment hole 20 of the expanding portion 41 is stated as follows: D3>D4>D1. However, the expanding portion 41 can be formed in a zone Z2 expanding from the deepest portion of the bottom 20a of the mounting hole 20 to the other end 2b. When the expanding portion 41 is formed in the zone Z2, at step S5, the zone Z2 is applied with silicone and heated, or the zone Z2 is heated without applying silicone, thereby forming the expanding portion 41 in the zone Z2 by thermal expansion.
In the above-mentioned embodiments, a cork stopper coated with a resin layer is used for a container for whisky. The container may also be used for beverages such as brandy, wine, champagne, Japanese sake or juice. The shape of the cork stopper coated with a resin layer 1 in
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-257810 | Dec 2013 | JP | national |
