Roll-fed shrink film
AssigneeUpm Raflatac Oy
InventorNoel Mitchell
Life of this patent
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Abstract
The invention relates to a shrink film having a multilayer structure, wherein the core layer of the film includes polypropylene, hydrocarbon resin and block-copolymer rubber. The invention also relates to a label including said film and to use of films for labelling recyclable or reusable items. Further the invention relates to a method for producing shrink film, to a method for attaching a shrink film to an article, and to a method separating a shrink film from an article.
Claims19
A shrink film (1) having a multilayer structure comprising:
- a core layer (2) having an first surface and a second surface;
- a first skin layer (4) on the first surface of the core layer;
- a second skin layer (14) on the second surface of the core layer,
- wherein the core layer (2) comprises polypropylene, hydrocarbon resin and block-copolymer rubber.
The shrink film according to any of the previous claims, wherein the block-copolymer rubber is at least one of the following:
- styrene-butylene/styrene, styrene-isoprene/styrene, styrene-ethylene/butylene-styrene, styrene-ethylene/propylene-styrene, styrene-ethylene-ethylene/propylene-styrene, or styrene-ethylene/propylene block copolymer.
The shrink film according to any of the previous claims, wherein the polypropylene is at least one of the following:
- a homopolymer, a random copolymer, or a block-copolymer.
The shrink film according to any of the previous claims, wherein a haze of the core layer (2) is less than 15%.
The shrink film according to any of the previous claims, wherein the first and second skin layer comprises polypropylene homopolymer, polypropylene random copolymer, polypropylene block-copolymer or any blend thereof.
The shrink film according to any of the previous claims, wherein the film (1) is oriented from 7 to 8 times in machine direction.
The shrink film according to any of the previous claims, wherein shrinkage of the film (1) is at least 30% at temperature between 120 and 130° C.
The shrink film according to any of the previous claims, wherein the overall density of the film is less than 1 g/cm3.
A method for producing a shrink film (1), the method comprising:
- producing of a non-oriented multilayer film comprising a core layer (2) having a first surface and a second surface, a first skin layer (4) on the first surface of the core layer and a second skin layer (14) on the second surface of the core layer, wherein the core layer comprises polypropylene, hydrocarbon resin and block-copolymer rubber;
- stretching said non-oriented multilayer film from 7 to 8 times in machine direction at temperature between 130 and 160° C.;
- and
- cooling the stretched film at temperature preferably between 50 and 80° C. so as to form a shrink film (1).
A method for attaching a shrink film (1) to an article (3), wherein the film comprises a core layer (2) including polypropylene, hydrocarbon resin and block-copolymer rubber, the method comprising:
- wrapping the film (1) around the article (3), wherein a machine direction of the oriented film extends circumferentially around the article (3);
- seaming said film by gluing, laser welding, heat sealing, or ultrasonic bonding;
- and
- heating the film (1) at temperature between 120 and 130° C. so as to form a tight fitting film (1) for the article (3).
A method for separating a shrink film (1, 8) from a surface of an article (3), wherein the film (1, 8) comprises a core layer (2) including polypropylene, hydrocarbon resin and block-copolymer rubber,
- the method comprising exposing the film (1, 8) and the article (3) to flotation separation process.
Dependencies are inferred from the claim text.