Thermoplastic elastomer composition and ethylene-alpha-olefin copolymer

Abstract

A thermoplastic elastomer composition comprising 5 to 95 wt % of the following (A) and 5 to 95 wt % of the following (B), wherein the flowability index I according to a test for flow properties with a capillary rheometer is 1.35 or more: (A) an ethylene-α-olefin copolymer having a tensile stress M 100 measured according to JIS-K-6251 of 2.5 MPa or less, (B) a polyolefin-based resin having a tensile stress M 100 measured according to JIS-K-6251 of 2.5 MPa or more.

What is claimed is:  
     
         1 . A thermoplastic elastomer composition comprising 5 to 95 wt % of the following (A) and 5 to 95 wt % of the following (B), wherein the flowability index I according to a test for flow properties with a capillary rheometer is 1.35 or more: 
 (A) an ethylene-α-olefin copolymer having a tensile stress M 100  measured according to JIS-K-6251 of 2.5 MPa or less,    (B) a polyolefin-based resin having a tensile stress M 100  measured according to JIS-K-6251 of 2.5 MPa or more.    
     
     
         2 . The thermoplastic elastomer composition according to  claim 1 , wherein (A) is an ethylene-α-olefin copolymer satisfying the following conditions (a) to (c): 
 (a) α-olefin content is from 5 to 95 wt %,  
 (b) Mooney viscosity: ML 1+4 100° C. is from 5 to 70,  
 (c) Q value (weight-average molecular chain length/number-average molecular chain length) according to GPC measurement is 4 or more.  
 
     
     
         3 . The thermoplastic elastomer composition according to  claim 2 , wherein (A) satisfies the conditions (a) to (c) and the following condition (d): 
 (d) a molecular weight distribution curve is bimodal.    
     
     
         4 . The thermoplastic elastomer composition according to  claim 3 , wherein (A) satisfies the conditions (a) to (d) and the following conditions (e) to (g): 
 (e) a ratio (H=X1/X2) of high molecular weight peak height X1 to low molecular weight peak height X2 in a molecular weight distribution curve is from 2.0 to 7.0,    (f) an area of low molecular weight parts having chain lengths of 100 Å or less in a molecular weight distribution curve is 3% or less,    (g) heat of fusion of a crystal at temperature of from 50 to 100° C. is 5 mJ/mg or more when measured by a differential scanning calorimeter (DSC).    
     
     
         5 . The thermoplastic elastomer composition according to  claim 4 , wherein (A) has an α-olefin content of from 20 to 40 wt % and has a Mooney viscosity: ML 1+4 100° C. of from 15 to 70.  
     
     
         6 . An extrusion molded article obtained by extrusion molding the thermoplastic elastomer composition according to  claim 1 .  
     
     
         7 . A hose obtained from the molded article according to  claim 6 .  
     
     
         8 . A tube obtained from the molded article according to  claim 6 .  
     
     
         9 . A gasket obtained from the molded article according to  claim 6 .  
     
     
         10 . A packing obtained from the molded article according to  claim 6 .  
     
     
         11 . A calender molded article obtained by calender molding the thermoplastic elastomer composition according to  claim 1 .  
     
     
         12 . An ethylene-α-olefin copolymer which comprises ethylene and an α-olefin having 3 to 8 carbon atoms, wherein the copolymer has an α-olefin content of from 20 to 40 wt %, has a Mooney viscosity: ML 1+4 100° C. of from 15 to 70, and satisfies the conditions (c) to (g) according to  claim 4 .  
     
     
         13 . The ethylene-α-olefin copolymer according to  claim 12 , wherein the α-olefin content is from 25 to 40 wt %.  
     
     
         14 . A pellet made of the ethylene-α-olefin copolymer according to  claim 12 .  
     
     
         15 . An extrusion molded article obtained by extrusion molding of the ethylene-α-olefin copolymer according to  claim 12 .  
     
     
         16 . A hose obtained from the molded article according to  claim 15 .  
     
     
         17 . A tube obtained from the molded article according to  claim 15 .  
     
     
         18 . A gasket obtained from the molded article according to  claim 15 .  
     
     
         19 . A packing obtained from the molded article according to  claim 15 .  
     
     
         20 . A calender molded article obtained by calender molding the thermoplastic elastomer composition according to  claim 12.