Patent Application
20070026173
The present disclosure relates to manufacture of multilayer plastic containers having particular application for use in the pharmaceutical industry.
Containers or vials for the pharmaceutical industry typically are of glass construction, which provides high clarity, moisture and oxygen permeation resistance, heat resistance for sterilization and retort applications, and chemical resistance. However, the glass containers are highly susceptible to breakage. It has been proposed to provide multilayer plastic containers for the pharmaceutical industry that have the benefits of glass containers and additionally are of significantly reduced susceptibility to breakage. Such multilayer plastic containers have been of three-layer construction, consisting of inner and outer layers of polycarbonate with an intermediate barrier layer of nylon, inner and outer layers of polycarbonate or polyethylene with an intermediate barrier layer of cyclic olefin copolymer, and inner and outer layers of cyclic olefin copolymer with an intermediate barrier layer of nylon.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A blow molded plastic container in accordance with of the present disclosure includes a multilayer sidewall having at least three consecutive layers A, B and C. Layers A and C are of identical plastic composition, and of a composition different from layer B. Layers A and C in accordance with one aspect of the disclosure are of a composition selected from the group consisting of cyclic olefin polymers, cyclic olefin copolymers, acrylonitriles (i.e., acrylonitrile-based materials), and blends thereof, and layer B is of a composition selected from the group consisting of cyclic olefin polymers, cyclic olefin copolymers, polycarbonates and blends thereof. In accordance with another aspect of the disclosure, layers A and C are of a composition selected from the group consisting of polycarbonates, acrylonitriles and blends thereof, while layer B is of a composition selected from the group consisting of nylons, polycarbonates and blends thereof. In accordance with a third aspect of the disclosure, layers A and C are of acrylonitrile composition, and layer B is of ethylene vinyl alcohol composition.
In accordance with a further aspect of the disclosure, the plastic materials for the container layers are fed to a molding system through respective extruders. Inert gas is fed through at least the extruder associated with layer B to prevent oxidation of the layer material during the extrusion process. In accordance with another aspect of the disclosure, the container is blow molded from a preform, and heat is applied to the blow mold independently of the preform. This feature provides enhanced control of the container properties. Gas under pressure is applied to the preform during the blow molding operation, and the gas preferably is conditioned further to enhance the container properties.
The disclosure, together with additional objects, features, advantages and aspects thereof, will best be understood from the following description, the appended claims and the accompanying drawings, in which:
In each embodiment of the disclosure, layers A and C are of identical plastic composition, and are of a plastic composition different from layer B. In one embodiment of the disclosure, layers A and C are of a composition selected from the group consisting of cyclic olefin polymers (COPs), cyclic olefin copolymers (COCs) and acrylonitriles, while layer B is of a composition selected from the group consisting of cyclic olefin polymers, cyclic olefin copolymers and polycarbonates (PCs). (Inasmuch as layer B is of a composition different from layers A and C, it will be understood that, if layers A and C are of cyclic olefin copolymer, for example, layers B must be of polycarbonate composition in this example.). In another aspect of the disclosure, layers A and C are of a composition selected from the group consisting of polycarbonates and acrylonitriles, while layer B is of a composition selected from the group consisting of nylons and polycarbonates. In a third aspect of the disclosure, layers A and C are of acrylonitrile composition, while layer B is of ethylene vinyl alcohol (EVOH) composition. All of these embodiments provide one or more of the desired properties of the container, such as high clarity, moisture and oxygen permeation resistance, heat resistance for sterilization and retort applications, chemical (e.g., oil and lipids) resistance, gamma radiation resistance, breakage resistance, etc.
The containers of the present disclosure can be fabricated in any suitable molding operation, including but not limited to injection blow molding, reheat blow molding, extrusion blow molding, injection molding, thermoforming and compression molding. Blow molding processes are preferred, which involve formation of a preform, whether by injection molding, compression molding or extrusion, and blow molding the preform in a blow mold. In injection blow molding, the materials are injected sequentially or simultaneously into a mold to form a preform having multiple layers. A typical injection blow molding operation is illustrated in U.S. Pat. No. 3,707,591. Sequential injection of plastic materials to obtain a multilayer preform in an injection blow molding process is illustrated in U.S. Pat. Nos. 4,413,974 and 4,990,301. Shooting pots preferably are employed as a buffer between the plastic extruders and the injection molds to expedite production and/or to provide premeasured amounts of relevant materials, as illustrated for example in U.S. Pat. No. 5,098,274. Exemplary extrusion blow molding processes are illustrated in U.S. Pat. Nos. 3,031,718, 3,114,594, 3,409,710 and 5,188,849. Exemplary reheat blow molding processes are illustrated in U.S. Patent documents 4,550,043, 4,990,301 and 2004/0091652.
There thus have been disclosed a blow molded plastic container having particular application for the pharmaceutical industry, and a method of forming such a container. The disclosure has been presented in conjunction with several exemplary embodiments and implementations, and additional modifications and variations have been discussed. Other modifications and variations readily will suggest themselves to persons of ordinary skill in the art in view of the foregoing description. The disclosure is intended to embrace all such modifications and variations as fall within the spirit and broad scope of the appended claims.
