Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
2001-10-15
2004-01-06
Pyon, Harold (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S516000, C428S518000, C428S036910, C428S036920, C428S035700, C524S114000, C524S306000, C524S308000, C524S310000
Reexamination Certificate
active
06673406
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to compositions and films made from vinylidene chloride copolymers, especially films suitable for the packaging of pharmaceutical products in blister packs.
BACKGROUND OF THE INVENTION
The present invention relates to films suitable for making blister packs for pharmaceuticals.
Conventional blister packs typically include a base with one or, more commonly, a plurality of recesses that are surrounded by a shoulder, and a lid attached to the shoulder. Tablets, capsules, or other contents are accommodated in respective recesses, and may be removed therefrom by (1) pressing on the respective recess, thus making the contents penetrate the lid (usually an aluminum foil or the like), or by (2) removing the portion of the lid lying over the recess, thus gaining access to the contents of the recess.
In practice, a base is formed with recesses, and with a shoulder defining the base material in between the recesses; the recesses of the base are filled with tablets, etc.; the base, with the filled recesses, is covered with a lid; and the lid is sealed or otherwise adhered to the shoulder of the base.
The base of the blister pack is sometimes made up of an interior portion (to be adhered to the lid) of ACLAR™ PTFE (polychlorotrifluoroethylene), a material that is very expensive, and with less than optimal oxygen barrier properties. This material displays an MVTR of typically about 0.4 grams/m
2
. The exterior portion of the base is often a PVC (polyvinyl chloride) of about 250 micrometers (10 mils) thickness. PVC, polyamides, polyolefins, polyesters are other materials which can be used to making the base. An aluminum foil can be added to the base.
The lid is typically made of aluminum foil or an aluminum foil laminate. Aluminum foil is a preferred material for the lids on blister packs as the thickness of the material employed requires relatively little force for it to rupture. Consequently, the energy for penetration is low and the aluminum exhibits essentially no elasticity. Plastic laminates may also be employed for the lid.
Some blister packs feature a lid provided with a line of weakness in the region of each recess. In others, each recess may be covered with an individual lid segment. Within the line of weakness or on each lid segment may be a tab for gripping which enables the individual recess to be exposed by peeling back the lid segment.
Provision of a vinylidene chloride copolymer, often referred to as “saran” or “PVDC”, in a PVDC composition capable of providing a packaging film with a low moisture vapor transmission rate (MVTR), and preferably also a low oxygen transmission rate (OTR), would be desirable for applications such as the blister packaging of pharmaceutical products sensitive to both oxygen and moisture.
Stabilizers are often used in formulating PVDC-based compositions. These stabilizers reduce the thermal degradation of PVDC formulations during extrusion. Unfortunately, a trade-off in OTR and thermal stability must sometimes be made in designing such formulations. Thus, a composition having increased amounts of a stabilizer will sometimes result in enhanced thermal stability, but at the expense of oxygen barrier properties. Conversely, improved (lower) OTR can be obtained by lowering the relative amounts of stabilizer in the formulation, but this may result in a less stable PVDC composition.
The inventor has produced a composition that provides good moisture vapor and oxygen barrier properties, but without significant loss of thermal stability.
SUMMARY OF THE INVENTION
In a first aspect, a polymeric film comprises at least one layer, the at least one layer comprising a vinylidene chloride composition, the composition comprising 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a stabilizer; between 0.1 and 10 parts, by weight of the composition, of a lubricant; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a second aspect, a polymeric film comprises at least one layer, the at least one layer comprising a vinylidene chloride composition, the composition comprising 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a soap of a fatty acid; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a third aspect, a blister pack comprises a base, the base comprising a plurality of recesses, and a shoulder surrounding the recesses; a lid attached to the shoulder; and contents disposed in respective recesses; wherein at least one of the base and lid comprises a vinylidene composition, the composition comprising 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a stabilizer; between 0.1 and 10 parts, by weight of the composition, of a lubricant; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a fourth aspect, a blister pack comprises a base, the base comprising a plurality of recesses, and a shoulder surrounding the recesses; a lid attached to the shoulder; and contents disposed in respective recesses; wherein at least one of the base and lid comprises a vinylidene composition, the composition comprising 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a soap of a fatty acid; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a fifth aspect, a vinylidene chloride composition comprises 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a stabilizer; between 0.1 and 10 parts, by weight of the composition, of a lubricant; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
In a sixth aspect, a vinylidene chloride composition comprises 100 parts, by weight of the composition, of a vinylidene chloride copolymer; between 0.1 and 10 parts, by weight of the composition, of a soap of a fatty acid; and between 0.1 and 10 parts, by weight of the composition, of a hydrophilic clay.
Definitions
“(meth)acrylic acid” herein refers to both acrylic acid and/or methacrylic acid;
“(meth)acrylate” herein refers to both acrylate and methacrylate;
“polymer” herein refers to the product of a polymerization reaction, and is inclusive of homopolymers, copolymers, terpolymers, tetrapolymers, etc.;
“copolymer” herein refers to a polymer formed by the polymerization reaction of at least two different monomers and is inclusive of random copolymers, block copolymers, graft copolymers, etc.;
“ethylene/alpha-olefin copolymer” (EAO) herein refers to copolymers of ethylene with one or more comonomers selected from C
3
to C
10
alpha-olefins such as propene, butene-1,hexene-1, octene-1, etc. in which the molecules of the copolymers comprise long polymer chains with relatively few side chain branches arising from the alpha-olefin which was reacted with ethylene. This molecular structure is to be contrasted with conventional high pressure low or medium density polyethylenes which are highly branched with respect to EAOs and which high pressure polyethylenes contain both long chain and short chain branches. EAO includes such heterogeneous materials as linear medium density polyethylene (LMDPE), linear low density polyethylene (LLDPE), and very low and ultra low density polyethylene (VLDPE and ULDPE), such as DOWLEX™ or ATTANET™ resins supplied by Dow, ESCORENET™ or EXCEED™ resins supplied by Exxon; as well as linear homogeneous ethylene/alpha olefin copolymers (HEAO) such as TAFMER™ resins supplied by Mitsui Petrochemical Corporation, EXACT™ resins supplied by Exxon, or long chain branched (HEAO) AFFINITY™ resins supplied by the Dow Chemical Company, or ENGAGE™ resins supplied by DuPont Dow Elastomers;
“package” herein refers to a film configured around a product;
“
Cryovac Inc.
Pyon Harold
Quatt Mark B.
Simone Catherine A.
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