Biaxially-stretched film and ethylene polymer composition

Abstract

Provided is a biaxially-stretched film wherein the biaxial stretching is possible in a broader temperature range and which is excellent in thickness accuracy, and an ethylene polymer composition serving as a raw material of the film. The biaxially-stretched film of the present invention is obtained from an ethylene polymer composition (E) including a specific ethylene polymer component (A) containing 20 to 100 wt % of an ethylene polymer (a) being a copolymer of ethylene and a C4-10 α-olefin and having specific melt flow rate and density, and an ethylene polymer component (B) being another copolymer of ethylene and a C4-10 α-olefin, wherein a weight fraction [WA] of the ethylene polymer component (A) is 0.50 or more and 0.92 or less, and a weight fraction [WB] of the ethylene polymer component (B) is 0.08 or more and 0.50 or less provided that WA and WB total 1.0.

1 - 6 . (canceled) 
     
     
         7 . A biaxially-stretched film obtained from an ethylene polymer composition (E) comprising an ethylene polymer component (A) fulfilling requirements described below and an ethylene polymer component (B) fulfilling requirements described below,
 wherein a weight fraction [W A ] of the ethylene polymer component (A) is 0.50 or more and 0.87 or less, and a weight fraction [W B ] of the ethylene polymer component (B) is 0.13 or more and 0.50 or less provided that W A  and W B  total 1.0,   wherein the ethylene polymer component (A) comprises an ethylene polymer (a) described below at 20% by weight or more and 100% by weight or less and fulfills requirements (A-1) to (A-3) described below:   (A-1) Melt flow rate (MFR A ) at 190° C. under a load of 2.16 kg is not less than 0.1 g/10 min and not more than 3 g/10 min;   (A-2) Density (D A ) is 907 kg/m 3  or more and 940 kg/m 3  or less; and   (A-3) Ratio [η]/Mw 0.776  of intrinsic viscosity measured in decalin at 135° C. [[η] (dl/g)] to weight average molecular weight measured by GPC-viscometry (GPC-VISCO) to the power 0.776 (Mw 0.776 ) is not less than 1.90×10 −4  and not more than 2.80×10 −4 , and   wherein the ethylene polymer component (B) is a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and fulfills requirements (B-1) to (B-5) described below:   (B-1) Melt flow rate (MFR B ) at 190° C. under a load of 2.16 kg is not less than 0.01 g/10 min and not more than 30 g/10 min;   (B-2) Density (D B ) is 915 kg/m 3  or more and 939 kg/m 3  or less;   (B-3) Sum of the number of methyl branches [Me(/1000 C)] and the number of ethyl branches [Et(/1000 C)] per 1000 carbon atoms in  13 C-NMR analysis [(Me+Et)(/1000 C)] is not more than 1.80;   (B-4) Ratio η 0 /Mw 6.8  of zero shear viscosity at 200° C. [η 0 (P)] to weight average molecular weight measured by GPC-viscometry (GPC-VISCO) to the power 6.8 (Mw 6.8 ) is not less than 0.03×10 −30  and not more than 7.5×10 −30 ; and   (B-5) Ratio [η]/Mw 0.776  of intrinsic viscosity measured in decalin at 135° C. [[η] (dl/g)] to weight average molecular weight measured by GPC-viscometry (GPC-VISCO) to the power 0.776 (Mw 0.776 ) is not less than 0.90×10 −4  and not more than 1.65×10 −4 ,   wherein the ethylene polymer (a) is a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and fulfills requirements (a-1) to (a-3) described below:   (a-1) Melt flow rate (MFR a ) at 190° C. under a load of 2.16 kg is not less than 0.1 g/10 min and not more than 0.6 g/10 min;   (a-2) Density (D a ) is 890 kg/m 3  or more and 928 kg/m 3  or less; and   (a-3) (D B −D a )≥1 kg/m 3 .   
     
     
         8 . The biaxially-stretched film according to  claim 7 , wherein the ethylene polymer component (A) further comprises an ethylene polymer (c) at 20% by weight or more and 50% by weight or less, and the ethylene polymer (c) fulfills requirements described below but does not fall within the ethylene polymer (a),
 wherein the ethylene polymer (c) is a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and fulfills requirements (c-1) to (c-4) described below:   (c-1) Melt flow rate (MFR c ) at 190° C. under a load of 2.16 kg is not less than 0.01 g/10 min and not more than 3000 g/10 min;   (c-2) (MFR c −MFR a )≥1 g/10 min;   (c-3) Density (D c ) is 900 kg/m 3  or more and 940 kg/m 3  or less; and   (c-4) (D c −D a )≥1 kg/m 3 .   
     
     
         9 . The biaxially-stretched film according to  claim 7 , wherein the ethylene polymer component (A) further comprises an ethylene polymer (d) fulfilling requirements described below at 10% by weight or more and 50% by weight or less,
 wherein the ethylene polymer (d) is an ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms and fulfills requirements (d-1) and (d-2) described below:   (d-1) Melt flow rate (MFR d ) at 190° C. under a load of 2.16 kg is not less than 0.01 g/10 min and not more than 2 g/10 min.; and   (d-2) Density (D d ) is more than 940 kg/m 3  and 980 kg/m 3  or less.   
     
     
         10 . The biaxially-stretched film according to  claim 7 , having 5 to 10% of a thickness accuracy represented by (A MD ×A TD ) 1/2 , wherein A MD  is a thickness accuracy about the longitudinal direction (MD) of the biaxially-stretched film and A TD  is a thickness accuracy about the transverse direction (TD), each thickness accuracy being represented by 2σ/x, wherein σ and x are the standard deviation and the average thickness, respectively, of thicknesses of the biaxially-stretched film measured by cutting the biaxially-stretched film to A3 size and measuring thickness at 45 points in the longitudinal direction or at 45 points in the transverse direction. 
     
     
         11 . An ethylene polymer composition comprising an ethylene polymer component (A) fulfilling requirements described below and an ethylene polymer component (B) fulfilling requirements described below,
 wherein a weight fraction [W A ] of the ethylene polymer component (A) is 0.50 or more and 0.87 or less, and a weight fraction [W B ] of the ethylene polymer component (B) is 0.13 or more and 0.50 or less provided that W A  and W B  total 1.0,   wherein the ethylene polymer component (A) comprises an ethylene polymer (a) described below at 20% by weight or more and 100% by weight or less and fulfills requirements (A-1) to (A-3) described below:   (A-1) Melt flow rate (MFR A ) at 190° C. under a load of 2.16 kg is not less than 0.1 g/10 min and not more than 3 g/10 min;   (A-2) Density (D A ) is 907 kg/m 3  or more and 940 kg/m 3  or less; and   (A-3) Ratio [η]/Mw 0.776  of intrinsic viscosity measured in decalin at 135° C. [[η] (dl/g)] to weight average molecular weight measured by GPC-viscometry (GPC-VISCO) to the power 0.776 (Mw 0.776 ) is not less than 1.90×10 −4  and not more than 2.80×10 −4 , and   wherein the ethylene polymer component (B) is a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and fulfills requirements (B-1) to (B-5) described below:   (B-1) Melt flow rate (MFR B ) at 190° C. under a load of 2.16 kg is not less than 0.01 g/10 min and not more than 30 g/10 min;   (B-2) Density (D B ) is 915 kg/m 3  or more and 939 kg/m 3  or less;   (B-3) Sum of the number of methyl branches [Me(/1000 C)] and the number of ethyl branches [Et(11000 C)] per 1000 carbon atoms in  13 C-NMR analysis [(Me+Et)(11000 C)] is not more than 1.80;   (B-4) Ratio η 0 /Mw 6.8  of zero shear viscosity at 200° C. [η 0 (P)] to weight average molecular weight measured by GPC-viscometry (GPC-VISCO) to the power 6.8 (Mw 6.8 ) is not less than 0.03×10 −30  and not more than 7.5×10 −30 ; and   (B-5) Ratio [η]/Mw 0.776  of intrinsic viscosity measured in decalin at 135° C. [[η] (dl/g)] to weight average molecular weight measured by GPC-viscometry (GPC-VISCO) to the power 0.776 (Mw 0.776 ) is not less than 0.90×10 −4  and not more than 1.65×10 −4 ,   wherein the ethylene polymer (a) is a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and fulfills requirements (a-1) to (a-3) described below:   (a-1) Melt flow rate (MFR a ) at 190° C. under a load of 2.16 kg is not less than 0.1 g/10 min and not more than 0.6 g/10 min;   (a-2) Density (D a ) is 890 kg/m 3  or more and 928 kg/m 3  or less; and   (a-3) (D B −D a )≥1 kg/m 3 .   
     
     
         12 . The ethylene polymer composition according to  claim 11 , wherein the ethylene polymer component (A) further comprises an ethylene polymer (c) at 20% by weight or more and 50% by weight or less, and the ethylene polymer (c) fulfills requirements described below but does not fall within the ethylene polymer (a),
 wherein the ethylene polymer (c) is a copolymer of ethylene and an α-olefin having 4 to 10 carbon atoms and fulfills requirements (c-1) to (c-4) described below:   (c-1) Melt flow rate (MFR c ) at 190° C. under a load of 2.16 kg is not less than 0.01 g/10 min and not more than 3000 g/10 min;   (c-2) (MFR c −MFR a )≥1 g/10 min;   (c-3) Density (D c ) is 900 kg/m 3  or more and 940 kg/m 3  or less; and   (c-4) (D c −D a )≥1 kg/m 3 .   
     
     
         13 . The ethylene polymer composition according to  claim 11 , wherein the ethylene polymer component (A) further comprises an ethylene polymer (d) fulfilling requirements described below at 10% by weight or more and 50% by weight or less,
 wherein the ethylene polymer (d) is an ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms and fulfills requirements (d-1) and (d-2) described below:   (d-1) Melt flow rate (MFR d ) at 190° C. under a load of 2.16 kg is not less than 0.01 g/10 min and not more than 2 g/10 min.; and   (d-2) Density (D d ) is more than 940 kg/m 3  and 980 kg/m 3  or less.