Process for producing ethylene/unsaturated carboxylic acid copolymer, and said copolymer

Abstract

Provided is a process of effectively producing an ethylene/unsaturated carboxylic acid copolymer having excellent mechanical and thermal properties. A process for producing an ethylene/unsaturated carboxylic acid copolymer comprises: producing an ethylene/unsaturated carboxylic acid ester copolymer from ethylene and unsaturated carboxylic acid ester using a late-transition-metal complex catalyst; and heating the ethylene/unsaturated carboxylic acid ester copolymer at a temperature capable of converting the ester group into a carboxylic acid group, thereby converting into the ethylene/unsaturated carboxylic acid copolymer.

1 . A process for producing an ethylene/unsaturated carboxylic acid copolymer comprising a structural unit derived from ethylene and a structural unit derived from unsaturated carboxylic acid, which have been copolymerized randomly and linearly, wherein the process comprises: producing an ethylene/unsaturated carboxylic acid ester copolymer from ethylene and unsaturated carboxylic acid ester using a late-transition-metal complex catalyst; and heating the ethylene/unsaturated carboxylic acid ester copolymer at a temperature capable of converting the ester group into a carboxylic acid group, thereby converting into the ethylene/unsaturated carboxylic acid copolymer 
     
     
         2 . The process for producing an ethylene/unsaturated carboxylic acid copolymer according to  claim 1 , wherein the unsaturated carboxylic acid ester is (meth)acrylic acid ester and the unsaturated carboxylic acid is (meth)acrylic acid. 
     
     
         3 . The process for producing an ethylene/unsaturated carboxylic acid copolymer according to  claim 1 , wherein a temperature of the heating is 150-350° C. 
     
     
         4 . The process for producing an ethylene/unsaturated carboxylic acid copolymer according to  claim 1 , wherein the late-transition-metal complex catalyst is a catalyst comprising a late-transition-metal complex represented by the following formula (2):
   (Ligand)MRL   (2)
   
       [In formula (2), M represents a transition metal in Groups 9 to 11, “Ligand” represents a ligand which chelate-coordinates to the central-metal M through one or more atoms selected from the group consisting of oxygen, nitrogen, phosphorus, arsenic, sulfur, and carbon atoms. R represents a ligand which forms a 6-bond with the M, and L represents a ligand which coordinates to the M.] 
     
     
         5 . The process for producing an ethylene/unsaturated carboxylic acid copolymer according to  claim 1 , wherein the late-transition-metal complex is a phosphine-phenolate complex or a phosphine-sulfonate complex. 
     
     
         6 . The process for producing an ethylene/unsaturated carboxylic acid copolymer according to  claim 1 , wherein the unsaturated carboxylic acid ester is (meth)acrylic acid ester and the alcohol moiety of the (meth)acrylic acid ester is a tertiary alcohol. 
     
     
         7 . An ethylene/unsaturated carboxylic acid copolymer which has been produced by the production process according to  claim 1 . 
     
     
         8 . An ethylene/(meth)acrylic acid copolymer which has been produced by the production process according to  claim 1 . 
     
     
         9 . An ethylene/(meth)acrylic acid copolymer which comprises 99.9-80.0 mol % of ethylene units and 0.1-20.0 mol % of (meth)acrylic acid units, and which has the following features (a) to (c):
 (a) To have a weight-average molecular weight (Mw) as determined by GPC of 20,000 or higher but less than 1,000,000;   (b) To have a weight-average molecular weight/number-average molecular weight (Mw/Mn) as determined by GPC of 1.7-20; and   (c) The melting point (Tm, ° C.) of the copolymer measured in an examination with a DSC (differential scanning calorimeter) and the content (AA, mol %) of (meth)acrylic acid units in the copolymer satisfy the following expression (I):
   −3.74×AA+113.5<Tm<−3.74×AA+130   (I)
 
   
     
     
         10 . The ethylene/(meth)acrylic acid copolymer according to  claim 9 , wherein the melting point (Tm) is 80-128° C.