Shrink film having balanced properties or improved toughness and methods of making the same

A shrink film comprising a polymer composition, the polymer composition characterized as having a density in the range of 0.88 gram/centimeter (g/cc) to 0.94 g/cc, as determined in accordance with ASTM D-792, and as comprising and made from

• (A) from 20 to 80 weight percent, based on the total weight of the polymer composition, of at least one first ethylene polymer characterized as having
• (i) a single melting peak, as determined using differential scanning calorimetry (DSC), or a single Analytical Temperature Rising Elution Fractionation (ATREF) peak, and
• (ii) a density in the range of 0.87 (g/cc) to 0.93 g/cc, as determined in accordance with ASTM D-792, and
• (B) from 20 to 80 weight percent, based on the total weight of the polymer composition, of at least one second ethylene polymer characterized as having
• (i) one or more melting peaks, as determined using differential scanning calorimetry (DSC), and
• (ii) a density in the range of 0.89 (g/cc) to 0.96 g/cc, as determined in accordance with ASTM D-792,
• wherein the density differential between the first and second ethylene polymer components, determined in accordance with ASTM D-792, is in the range of from 0 to 0.018 g/cc.

A shrink film comprising a polymer composition, the polymer composition having a density in the range of from 0.88 gram/centimeter (g/cc) to 0.94 g/cc, and comprising and made from

• (C) from 20 to 80 weight percent, based on the total weight of the polymer composition, of at least one first ethylene polymer, wherein the at least one first ethylene polymer is manufactured using a single site metallocene or constrained geometry catalyst system and is characterized as having:
• (i) one or more melting peaks, as determined using differential scanning calorimetry (DSC),
• (ii) a short chain branching index (SCBDI) or composition distribution branching index (CDBI) greater than 50 percent, as determined using temperature rising elution fractionation,
• (iii) a melt index, as determined in accordance with ASTM D-1238, and
• (iv) a density in the range of from 0.87 (g/cc) to 0.93 g/cc, and
• (D) from 20 to 80 weight percent, based on the total weight of the polymer composition, of at least one second ethylene polymer characterized as having:
• (i) one or more melting peaks, as determined using differential scanning calorimetry (DSC),
• (ii) a melt index, as determined in accordance with ASTM B-1238, equal to or lower than the melt index of the first ethylene polymer and
• (iii) a density in the range of from 0.89 (g/cc) to 0.96 g/cc,
• wherein the density differential between the first and second ethylene polymer components (C) and (D) is in the range of from 0.001 to 0.018 g/cc and the density of the at least one first ethylene polymer (C) is lower than the density of the least one second ethylene polymer (D), and wherein the density for polymer components (C) and (D) and for the polymer composition is determined in accordance with ASTM D-792.

A method of making a shrink film having balanced properties comprising

• (a) providing a polymer composition having a density in the range of about 0.88 gram/centimeter (g/cc) to about 0.94 g/cc as determined in accordance with ASTM D-792 and which comprises and is made from
• i. from about 20 to about 80 weight percent, based on the total weight of the polymer composition, of at least one first ethylene polymer characterized as having a single melting peak as determined using differential scanning calorimetry (DSC) or a single Analytical Temperature Rising Elution Fractionation (ATREF) peak and a density in the range of about 0.87 (g/cc) to about 0.93 g/cc as determined in accordance with ASTM D-792, and
• ii. from about 20 to about 80 weight percent, based on the total weight of the polymer composition, of at least one second ethylene polymer characterized as having one or more melting peaks as determined using differential scanning calorimetry (DSC) and a density in the range of about 0.89 (g/cc) to about 0.96 g/cc as determined in accordance with ASTM D-79,
• wherein the density differential between the first and second ethylene polymer components, determined in accordance with ASTM D-792, is in the range of from about 0 to about 0.018 g/cc,
• (b) fabricating the polymer composition into a substantially unoriented film,
• (c) thereafter stretching the fabricated substantially unoriented film structure at a selected stretching rate, stretch ratio and stretching temperature, and
• (d) collecting the oriented film.

A method of making a shrink film having improved toughness comprising

• a. providing a polymer composition having a density in the range of from about 0.88 gram/centimeter (g/cc) to about 0.94 g/cc and which comprises and is made from
• i. from about 20 to about 80 weight percent, based on the total weight of the polymer composition, of at least one first ethylene polymer, wherein the at least one first ethylene polymer is manufactured using a single site metallocene or constrained geometry catalyst system and is characterized as having:
• (a) one or more melting peaks, as determined using differential scanning calorimetry (DSC),
• (b) a short chain branching index (SCBDI) or composition distribution branching index (CDBI) greater than about 50 percent,
• (c) a melt index determined in accordance with ASTM D-1238, and
• (d) a density in the range of from about 0.87 (g/cc) to about 0.93 g/cc, and
• ii. from about 20 to about 80 weight percent, based on the total weight of the polymer composition, of at least one second ethylene polymer characterized as having:
• (a) one or more melting peaks, as determined using differential scanning calorimetry (DSC),
• (b) a melt index equal to or lower than the melt index of the first ethylene polymer, as determined in accordance with ASTM B-1238, and
• (c) a density in the range of from about 0.89 (g/cc) to about 0.96 g/cc,
• wherein the density differential between the first and second ethylene polymer components is in the range of from about 0.001 to about 0.018 g/cc and the density of the at least one first ethylene polymer is lower than the density of the least one second ethylene polymer, and wherein the density of the at least one first ethylene polymer, the least one second ethylene polymer and the polymer composition is determined in accordance with ASTM D-792;
• b. fabricating the polymer composition into a substantially unoriented film;
• c. thereafter stretching the fabricated substantially unoriented film structure at a selected stretching rate, stretch ratio and stretching temperature;
• and
• d. collecting the oriented film.