Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Patent
1995-09-29
1998-08-11
Nold, Charles
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
428218, 428340, 428545, B32B 2732, B65D 100
Patent
active
057925267
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a multilayer film and a container formed by using the same. specifically, it is used in the medical field, especially as a container for pharmaceutical solution, blood or the like.
BACKGROUND ART
As conventional examples of multilayer container for medical use, the following compositions made of polyethylene resin may be listed.
A three-layer bag composed of linear low density polyethylene, with the density of inner and outer layers being 0.920 g/cm.sup.3 or more and the density of a middle layer being less than 0.920 g/cm.sup.3.
A three-layer container composed of linear low density polyethylene, with the density of inner and outer layers being 0.910 to 0.940 g/cm.sup.3 or more, the density of a middle layer being 0.880 to 0.905 g/cm.sup.3, and a difference in the density between the two being 0.01 g/cm.sup.3 or more.
A three-layer bag comprising an outer layer of linear low density polyethylene with the density of 0.920 g/cm.sup.3 or more, a middle layer of linear low density polyethylene with the density of 0.915 g/cm.sup.3 or less, and an inner layer of branched low density polyethylene with the density of 0.918 g/cm.sup.3 or more.
A bag of three layers or more comprising inner and outer layers composed of a resin in which 5 to 40% of high density polyethylene with the density of 0.945 g/cm.sup.3 or more is mixed with a low density polyethylene having long-chain branches with the density of 0.930 g/cm.sup.3 or less, and a middle layer composed of a resin in which 15% or less of the same high density polyethylene is mixed with a linear low density polyethylene with the density of 0.920 g/cm.sup.3 or less.
These compositions, however, have at least one of the following problems:
(1) Since the inner and outer layers are composed of polyethylene resin of low density, heat resistance is insufficient, and seal strength and drop-shock resistance are lowered by high pressure steam sterilization, hot water sterilization, or other sterilization in high temperature condition.
(2) Blocking is liable to occur after such sterilization in high temperature condition.
(3) Wall thickness must be increased in order to enhance the strength of the entire film.
(4) Since tensile strength is insufficient, the production of the bag cannot be speeded up.
(5) Since the temperature of a heater cannot be increased during heat sealing, it is impossible to seal in a short time.
(6) The transparency or flexibility is lowered after sterilization or the like.
It is therefore a primary object of the invention to produce a film and a container suited for medical use, while eliminating all the above problems.
SUMMARY OF THE INVENTION
To achieve the above object, a multilayer film of the invention is a five-layer resin film comprising one or more ethylene-.alpha.-olefin copolymers in each resin layer wherein the density of the resin comprising each layer is as follows, in order from the outer layer:
In the multilayer film of the invention, to the resin of the fifth layer, ethylene-.alpha.-olefin copolymer with a density of 0.945 g/cm.sup.3 or more may be added in an amount up to 10% by weight.
Furthermore, in the multilayer film of the invention, the resin comprising the second layer and fourth layer is preferably:
(1) A mixed resin comprising 40 to 60% by weight of ethylene-.alpha.-olefin copolymer with density of 0.900 to 0.920 g/cm.sup.3, 40 to 60% by weight of ethylene-.alpha.-olefin in elastomer with density of less than 0.900 g/cm.sup.3, and less than 5% by weight of high density polyethylene with density of 0.955 g/cm.sup.3 or more,
(2) A mixed resin comprising 20 to 60% by weight of ethylene-.alpha.-olefin copolymer with density of 0.900 to 0.920 g/cm.sup.3, 40 to 60% by weight of ethylene-.alpha.-olefin elastomer with density of less than 0.900 g/cm.sup.3, and 30% by weight or less of ethylene-.alpha.-olefin copolymer with density of 0.935 to 0.945 g/cm.sup.3, or
(3) A mixed resin comprising 20 to 50% by weight of ethylene-.alpha.-olefin copolymer with density of 0.93
REFERENCES:
patent: 4196240 (1980-04-01), Lustig et al.
patent: 4952451 (1990-08-01), Mueller et al.
patent: 5478617 (1995-12-01), Watanabe et al.
patent: 5520975 (1996-05-01), Inoue et al.
Okamoto Hideshi
Taniguchi Hirohisa
Watanabe Katsushi
Nold Charles
Otsuka Pharmaceutical Factory Inc.
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