POLYMERIC SHEETS AND ARTICLES WRAPPED THEREWITH

Abstract

A polymeric sheet having low density and comprising a low to non-existent amount of cyclic olefinic polymers (COP) and/or cyclic olefinic copolymers (COC). The overall density of the sheet may be lower than water. The sheet may be stretched and then heat shrinked onto an article. The sheet may be used as a label or package to wrap articles therewith.

Claims

1. A method comprising: selecting a polymeric film roll; wherein the polymeric film roll is configured to be used in a machine direction labeling system; and wherein the polymeric film roll comprises: a polymeric film; wherein the film has a density less than 1 g/cm3; wherein the density is calculated as follows: exposing the film to a temperature of 100 degrees Celsius to shrink the film and measuring the density of the film after shrinkage; wherein the film is configured to be shrinkable in a machine direction of the film roll by at least 15% upon exposing the film to 100 degrees Celsius with a steam tunnel, wherein the film is configured to be shrinkable in a transverse direction of the film roll by less than 5% upon exposing the film to 100 degrees Celsius with a steam tunnel, wherein the film is configured to be used as a sheet in a machine direction labeling system, and wherein the film is selected from the group consisting of cyclic olefinic polymer, cyclic olefinic copolymer, styrene polymer, styrene copolymer, ethylene polymer, ethylene copolymer, polypropylene polymer, polypropylene copolymer, and mixtures thereof; applying the film to a bottle in a machine direction labeling system; and shrinking the film applied to the bottle in the machine direction labeling system in a steam tunnel to form a shrink-wrapped bottle.

2. The method of claim 1: wherein a total amount of the cyclic olefinic polymer, the cyclic olefinic copolymer and the mixtures thereof is less than 40%.

3. The method of claim 1: wherein the film includes the styrene polymer.

4. The method of claim 1: wherein the film includes the ethylene polymer.

Description

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0024] In order to better understand the invention and to see how it may be carried out in practice, some exemplary embodiments will now be described.

EXAMPLE 1

[0025] A multi-layer polymeric film, 50 micrometers in thickness, was produced by a blown film process from two polyolefin resins. One of the resins was mLLDPE (metallocene linear low density polyethylene) produced by ExxonMobil and sold under the trade-name of EXCEED™ 1018CA, the density of which being 0.918 g/cm.sup.3, and the other resin was COC produced by Ticona and sold under the trade-name of Topas®, the density of which being 1.02 g/cm.sup.3. The multi-layer film was processed in a short-gap-stretching machine produced by Lenzing Aktiengesellschaft, described in U.S. Pat. No. 5,184,379, at a heating temperature of 90° C.-120° C. and a stretch ratio of 1:3 to produce a monoaxially heat shrinkable film.

[0026] This film was found to undergo shrinkage, in the monoaxial direction, to 20% of it's original dimension (80% shrink), upon heating to 100° C., and to 40% of it's original dimension (60% shrink) upon subsequent heating to 110° C.-120° C. and offered excellent transparency of as low as 3.0% HAZE (ASTM D 1003). The density of the film after shrinkage was about 0.96 g/cm.sup.3.

[0027] The obtained film was used for wrapping a polyethylene bottle having a feminine figure shape with a maximal outer diameter of 6.84 cm and minimal outer diameter of 6.05 cm. The wrapping was carried out on a KRONES roll-fed shrink labeling systems type Krones Contiroll 745-C96, with a steam tunnel at temperature of 100° C., at 20,000 bottles per hour.

[0028] The wrapping was carried out as follows: the film was wrapped around a drum, cut to form a label, and glue was applied to the label's edges. Then the label was wrapped around the bottle such that one glued edge attached the label to the bottle and the edges were glued to each other. The label was heated as to shrink onto the bottle.

EXAMPLE 2

[0029] A multi-layer polymeric film was prepared as in example 1, and was used for wrapping a mock-up bottle having a feminine figure shape with a maximal outer diameter of 6.84 cm and minimal outer diameter of 5.00 cm. The wrapping was carried out on a KRONES roll-fed shrink labeling systems type Krones Contiroll 745-C96, with a hot air tunnel at temperature of about 120° C., at 20,000 bottles per hour.

[0030] The wrapping was carried out as follows: the film was wrapped around a drum, cut to form a label, and glue was applied to the label's edges. Then the label was wrapped around the bottle such that one glued edge attached the label to the bottle and the edges were glued to each other. The label was heated as to shrink onto the bottle.

EXAMPLE 3

[0031] A multi-layer polymeric film, 50 micrometers in thickness, was produced by a blown film process from different resins. A inner layer was produced of the same mLLDPE (metallocene linear low density polyethylene) described in Example 1. The inner layer of mLLDPE was disposed between two outer layers of identical composition. The outer layers were produced from the following blend of polystyrene resins: (i) General Purpose Polystyrene (GPPS) produced by The Dow Chemical Company and sold under the trade-name of STYRON_678E™ the density of which being 1.05 g/cm.sup.3, and (ii) Styrene-butadiene Copolymer (SBC) produced by Chevron Phillips Chemical Company and sold under the trade-name of K-RESIN®, the density of which being 1.01 g/cm.sup.3, and (iii) High Impact Polystyrene (HIPS) produced by Chevron Phillips Chemical Company and sold under the trade-name of VALERA MA8000 the density of which being 1.05 g/cm.sup.3. The multi-layer film was processed in a short-gap-stretching machine produced by Lenzing Aktiengesellschaft, described in U.S. Pat. No. 5,184,379, at a heating temperature of 90° C.-120° C. and a stretch ratio of 1:4 to produce a monoaxially heat shrinkable film.

[0032] This film was found to undergo shrinkage in the monoaxial direction, to 85% of its original dimension (15% shrink) upon heating to 100° C., and to 40% of its original dimension (60% shrink) upon subsequent heating to 130° C.-140° C. The density of the film after shrinkage was about 0.97 g/cm.sup.3.

[0033] The obtained film was used for wrapping a PET (polyethylene terephthalate) bottle having a feminine figure shape with a maximal outer diameter of 6.75 cm and minimal outer diameter of 5.94 cm. The wrapping was carried out on a KRONES roll-fed shrink labeling systems type Krones Contiroll 745-C96, with a hot air tunnel at temperature of about 120° C., at 20,000 bottles per hour.

[0034] The wrapping was carried out as follows: the film was wrapped around a drum, cut to form a label, and glue was applied to the label's edges. Then the label was wrapped around the bottle such that one glued edge attached the label to the bottle and the edges were glued to each other. The label was heated as to shrink onto the bottle.

[0035] In the current example the density of the multi-layer polymeric film from which the label is made is about 0.97 g/cm.sup.3 and the density of the PET material from which the bottle is about 1.3 g/cm.sup.3, therefore, the material that the label is capable of floating when submerged in water and the bottle is inclined to sink in water. Consequently the different components of the article may be separated in a recycling process which utilizes water submersion for such a purpose.

EXAMPLE 4

[0036] A film was prepared as in example 1, but had a thickness of 25 micrometers. The transparency was excellent, as in the film of example 1.

[0037] The film was found to have the advantage of low back-twist, namely, after it is twisted, it has low tendency to release the twist. It was found that when a polymeric sheet according to the invention is twisted in 540 degrees (namely, one and a half full turns), the final twist achieved is of 375 degrees, which is slightly more than a full turn. A similar sheet but without the COC/COP provided final twist of 325 degrees, which is less than one turn. A similar sheet with the COC/COP but not stretched provided a final turn of 280°.

[0038] The film was successfully used for wrapping lollypops on an Aquarius™ machine. Those skilled in the art to which this invention pertains will readily appreciate that numerous changes, variations and modifications can be made without departing from the scope of the invention mutatis mutandis.