Stock material or miscellaneous articles – Hollow or container type article – Nonself-supporting tubular film or bag
Reexamination Certificate
1997-01-09
2001-04-03
Wilson, Donald R. (Department: 1713)
Stock material or miscellaneous articles
Hollow or container type article
Nonself-supporting tubular film or bag
C428S035400, C428S034900, C428S476100, C428S476900, C428S516000, C525S074000
Reexamination Certificate
active
06210765
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to adhesive polyethylene compositions and multi-layer laminated films using the compositions. More particularly, the invention relates to adhesive polyethylene compositions which are suitably used for bonding an ethylene polymer layer and a layer of a polyamide resin and/or an ethylene/vinyl alcohol copolymer, and the invention also relates to multi-layer laminated films using the compositions for adhesive layers.
BACKGROUND OF THE INVENTION
Laminated films of ethylene polymers and polyamide resins and laminated films of ethylene polymers and ethylene/vinyl alcohol copolymers have been conventionally known. Also, a variety of adhesive layer-forming materials used for producing the laminated films have been proposed. For example, Japanese Patent Laid-Open Publication No. 165413/1982 discloses that a modified polyethylene obtained by reacting a linear low-density polyethylene with an unsaturated carboxylic acid or derivative thereof and a modified polyethylene composition obtained by blending the modified polyethylene with a synthetic rubber and/or a linear low-density polyethylene are employable as the adhesive layer-forming materials. Japanese Patent Laid-Open Publication No. 165469/1982 discloses an adhesive resin composition obtained by modifying a mixture of a linear low-density polyethylene and a synthetic rubber with an unsaturated carboxylic acid or derivative thereof.
However, the adhesive layer-forming materials conventionally proposed have problems. For example, if the materials are subjected to stretching operation when preparing shrink films, the interlaminar strength between the ethylene polymer layer and the polyamide resin layer or the ethylene/vinyl alcohol copolymer layer may be sharply decreased, so that the resulting laminated films do not always exhibit satisfactory adhesion strength.
The shrink films are used, for example, for ham packaging various materials using an automatic packaging machine. In packaging, the film ends are heat sealed, and in the subsequent heat shrinking stage, a stress is applied to the heat sealed portions. Therefore, the shrink films are required to have high heat-sealing strength.
Moreover, in the case of food packaging, the shrink films are generally subjected to boiling sterilization treatments at temperatures as high as not lower than 80° C. after the packaging, so that the shrink films are required to have resistance to high temperatures of not lower than 80° C.
Accordingly, an adhesive polyethylene composition showing excellent adhesion strength to ethylene polymers, polyamide resins and ethylene/vinyl alcohol copolymers, high heat-sealing strength and heat resistance is desired. Also desired is a multi-layer laminated film wherein an adhesive layer of the composition is interposed between an ethylene polymer layer and a layer of a polyamide resin and/or an ethylene/vinyl alcohol copolymer.
OBJECT OF THE INVENTION
An object of the present invention is to provide an adhesive polyethylene composition showing excellent adhesion strength to ethylene polymers, polyamide resins and ethylene/vinyl alcohol copolymers and high heat-sealing strength, and heat resistance.
Another object of the invention is to provide a multi-layer laminated film wherein an adhesive layer of the adhesive polyethylene composition is interposed between an ethylene polymer layer and a layer of a polyamide resin and/or an ethylene/vinyl alcohol copolymer.
A further object of the invention is to provide a multi-layer laminated film having an adhesive layer of the above-mentioned adhesive polyethylene composition showing excellent adhesion strength in any of the unstretched and stretched states.
SUMMARY OF THE INVENTION
An adhesive polyethylene composition according to the invention is a composition comprising:
[I] a modified ethylene/&agr;-olefin copolymer resin [A2] or a modified ethylene/&agr;-olefin copolymer elastomer [B2] obtained by modifying an unmodified ethylene/&agr;-olefin copolymer resin [A1] or an unmodified ethylene/&agr;-olefin copolymer elastomer [B1], respectively, with an unsaturated carboxylic acid or derivative thereof and having a graft quantity of 0.01 to 5% by weight, each of said resin [A1] and elastomer [B1] being a copolymer of ethylene and an &agr;-olefin of 3 to 20 carbon atoms and having the following properties:
(i) the density is in the range of 0.860 to 0.930 g/cm
3
; and
(ii) the crystallinity, as measured by X-ray diffractometry, is not more than 60%;
[II] an unmodified ethylene/&agr;-olefin copolymer resin [C1] and/or an unmodified ethylene/&agr;-olefin copolymer elastomer [C2]; and
[III] a tackifier (D), wherein the composition has the following properties:
(a) the content of the tackifier [D] is in the range of 0.1 to 20% by weight based on 100% by weight of the whole composition;
(b) the graft quantity of the unsaturated carboxylic acid or derivative thereof is in the range of 0.01 to 1.0% by weight based on 100% by weight of the whole composition;
(c) the density is in the range of 0.880 to 0.920 g/cm
3
;
(d) the crystallinity, as measured by X-ray diffractometry, is in the range of 15 to 50%; and
(e) the melt flow rate (ASTM D 1238, 190° C., load of 2.16 kg) is in the range of 0.1 to 50 g/10 min.
The adhesive polyethylene composition of the invention is suitable as an adhesive resin composition for shrink films.
A multi-layer laminated film according to the invention is a laminate of 3 or more layers comprising an ethylene polymer layer [I] comprising an ethylene polymer having an ethylene content of not less than 70% by mol, an adhesive layer [II] comprising the adhesive polyethylene composition of the invention, and either of a polyamide resin layer [III], an ethylene/vinyl alcohol copolymer layer [IV] or a layer [V] of a mixture of a polyamide resin and an ethylene/vinyl alcohol copolymer, superposed in this order.
The ethylene polymer is preferably a low-density polyethylene or an ethylene/vinyl acetate copolymer.
DETAILED DESCRIPTION OF THE INVENTION
The adhesive polyethylene composition and the multi-layer laminated film using the composition according to the invention are described in detail hereinafter.
Adhesive Polyethylene Composition
First, the adhesive polyethylene composition of the invention is described.
The adhesive polyethylene composition of the invention comprises a modified ethylene/&agr;-olefin copolymer resin [A2] or a modified ethylene/&agr;-olefin copolymer elastomer [B2] obtained by grafting a specific ethylene/&agr;-olefin copolymer resin [A1] or a specific ethylene/&agr;-olefin copolymer elastomer [B1] with an unsaturated carboxylic acid or derivative thereof, and further comprises an unmodified ethylene/&agr;-olefin copolymer resin [C1] and/or an unmodified ethylene/&agr;-olefin copolymer elastomer [C2], and a tackifier [D].
Unmodified Ethylene/&agr;-olefin Copolymer Resin [A1], [C1]
The unmodified ethylene/&agr;-olefin copolymer resin [A1] used in the invention comprises ethylene and an &agr;-olefin of 3 to 20 carbon atoms.
The ethylene content in the ethylene/&agr;-olefin copolymer resin [A1] is not less than 70% by mol, preferably 75 to 95% by mol.
Examples of the &agr;-olefins include propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-l-pentene, 1-octene and 1-decene. Of these, preferably used are propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene. These &agr;-olefins can be used singly or in combination of two or more kinds.
The ethylene/&agr;-olefin copolymer resin [A1] has a density of 0.860 to 0.930 g/cm
3
, preferably more than 0.900 g/cm
3
and not more than 0.930 g/cm
3
, more preferably 0.905 to 0.925 g/cm
3
.
The temperature (melting point, Tm) giving the maximum peak of an endotherm curve of the ethylene/&agr;-olefin copolymer res
Inaba Masahiro
Kawachi Hideshi
Sawada Yuji
Tanaka Haruhiko
Mitsui Petrochemical Industrie Ltd
Wilson Donald R.
LandOfFree
Adhesive polyethylene compositions and multi-layer laminated... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Adhesive polyethylene compositions and multi-layer laminated..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Adhesive polyethylene compositions and multi-layer laminated... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2540802