Receptacles – Receptacle side wall made of two or more layers of material... – Thermoplastic layer
Reexamination Certificate
2000-04-13
2001-06-12
Castellano, Stephen (Department: 3727)
Receptacles
Receptacle side wall made of two or more layers of material...
Thermoplastic layer
C220S671000, C220S675000, C215S012200
Reexamination Certificate
active
06244454
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a multilayered thin container, and more particularly, to a novel multilayered thin container including a flexible cylindrical body and a high-rigidity neck portion on which a cap is to be fitted and which is integrally formed with the cylindrical body by a blow-molding method, and being suitable as transfusion containers, food containers, beverage containers or the like.
BACKGROUND ART
As medical transfusion containers, for example, various thin-walled containers whose body is produced from relatively flexible resins by a blow-molding method, have been proposed and used instead of so-called conventional transfusion bags produced by forming a film material into a flat bag. Alternatively, since such containers are extremely easy in handling, these thin-walled containers are deteriorated in liquid-discharging property and easy collapse property as compared to the transfusion bags, because these containers have a relatively high rigidity as a whole and a solid structure. Also, the transfusion containers have been required to be closed by fitting a cap on a neck (or mouth) portion thereof. For this reason, the neck portion of the thin-walled container is usually formed by welding a reinforcing neck member to the neck portion in a separate step after forming a container body, or by inserting such a neck member to the neck portion when blow-molding to produce the container body.
Incidentally, the conventional thin-walled containers have been produced using complicated production apparatuses or processes since it is necessary to use the separate neck member produced in the separate steps. Further, there arises such a problem that a portion of the container to which the neck member is fitted, tends to undergo pin holes. Accordingly, the present invention has been attained to solve these problems. An object of the present invention is to provide a novel multilayered thin container comprising a cylindrical body and a neck portion for cap-fitting, which exhibits a more excellent liquid-discharging property and easy collapse property, which is surely prevented from undergoing pin holes in the base portion of the neck for cap-fitting, and which can be produced by a much simpler process.
DISCLOSURE OF THE INVENTION
In order to accomplish the above-described object, in accordance with the present invention, there is provided a multilayered thin container comprising a cylindrical body and a neck portion for cap-fitting, which container is integrally produced by extrusion and blow molding, which container comprises an outer layer composed of a high-rigidity resin (i) having an elastic modulus of 2,000 to 23,000 kg/cm
2
and an inner layer composed of a low-rigidity resin (ii) having an elastic modulus of not more than 1,000 kg/cm
2
, wherein when extrusion-molding to form a parison, the amount of the high-rigidity resin (i) extruded for a portion corresponding to the neck portion is increased as compared to that corresponding to the cylindrical body so as to allow the neck portion to exhibit a higher rigidity than that of the cylindrical body; and the outer layer composed of the high-rigidity resin (i) is extruded into a sectional shape with a plurality of protrusions arranged in the circumferential direction, whereby the cylindrical body is formed with a plurality of ribs composed of the high-rigidity resin (i) and extending along an axis thereof.
That is, in the above multilayered thin container, such a structure in which the neck portion has a higher rigidity than that of the cylindrical body, enables the cylindrical body to maintain a good flexibility and the cap to be fitted onto the neck portion. Also, the parison extruded into the specified shape can be enhanced in moldability upon the blow-molding process, since the parison itself exhibits a high shape-retention property due to the ribbed structure constituted by the protrusions formed on the outer layer composed of high-rigidity resin. Further, by forming the ribs composed of high-rigidity resin on the cylindrical body of the blow-molded container, it is possible to impart a rigidity required when filled, to the cylindrical body. Accordingly, the cylindrical body can be further reduced in thickness of a portion other than the ribs, thereby enabling a liquid-discharging property and an easy collapse property of the container to be further enhanced.
In the above multilayered thin container, in order to enhance a setting stability and a standing property thereof, it is preferred that when extrusion-molding to form the parison, the amount of high-rigidity resin extruded for a portion corresponding to a bottom portion of the container is increased as compared to that corresponding to the cylindrical body so as to allow the bottom portion to exhibit a higher rigidity that of the cylindrical body.
In the preferred embodiment of the above multilayered thin container, the thickness of the cylindrical body is 0.3 to 2.0 mm. In addition, the thickness of the outer layer composed of high-rigidity resin at the neck portion is
20
to 99% based on the whole thickness of the neck portion, and the thickness of the outer layer composed of high-rigidity resin at the cylindrical body is 1 to 50% based on the whole thickness of the cylindrical body.
In the further preferred embodiment of the above multilayered thin container, the high-rigidity resin is polyethylene having a melt flow rate (MFR) of 0.10 to 2.0 g/10 min and a density of 0.940 to 0.970 cm
3
/g, or low-density polyethylene or linear low-density polyethylene having a melt flow rate (MFR) of 0.2 to 4.0 g/10 min and a density of 0.925 to 0.940 cm
3
/g; and the low-rigidity resin is polyethylene produced using a metallocene catalyst and having a density of 0.860 to 0.910 cm
3
/g or a polyethylene resin containing the polyethylene produced using a metallocene catalyst in an amount of not less than 50% by weight.
Further, in the above multilayered thin container, the high-rigidity resin may include polypropylene having a density of 0.885 to 0.935 cm
3
/g; and the low-rigidity resin may include polyethylene produced using a metallocene catalyst and having a density of 0.860 to 0.910 cm
3
/g or a polyethylene resin containing the above polyethylene in an amount of not less than 50% by weight.
Furthermore, in the above multilayered thin container, a gas-barrier layer composed of a gas-barrier resin may be further provided in order to prevent oxygen from being permeated therethrough. In the preferred embodiment of the multilayered thin container provided with the gas-barrier layer, the gas-barrier resin may be selected from ethylene-vinyl alcohol copolymer, polyamide and polyethylene naphthalate.
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Morisaki Hiroshi
Yoshioka Tsunemi
Castellano Stephen
Hanshin Kasei Co., Ltd.
Nixon & Vanderhye
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