POLYOLEFIN POLYMER HAVING POLAR GROUP, METHOD FOR PRODUCTION THEREOF, AND WATER DISPERSION MATERIAL AND MOLD RELEASE AGENT COMPOSITION

To provide a polyolefin polymer having a polar group represented by Formula (i) produced by modifying, with a high modification ratio, a double bond in a polymer having the double bond at one terminal, both terminals, or at the inside of a polymer chain thereof that is obtained by a known method; a method for producing the polyolefin polymer; and a water dispersion material and a mold release agent composition each containing the polyolefin polymer, wherein in Formula (i), PO represents a polyolefin polymer obtained by polymerizing a monomer including ethylene or including an olefin having 3 to 20 carbon atoms, and a group shown in the brackets is the polar group of the polyolefin polymer; A and B each independently represent R 1 , a cyano group, C(O)OR 1 , or C(O)NR 1 R 2 , and A and B may be combined to form a cyclic structure; M represents a metal cation or an onium cation; j is an integer of 0 to 4 representing the number of the metal cation or the onium cation; i is an integer of 0 to 4 representing the number of valency of the metal cation or the onium cation; D and E each independently represent an oxygen atom, a nitrogen atom, a sulfur atom, R 3 , OR 3 , SR 3 , or NR 3 R 4 , and D and E may be combined to form a cyclic structure; d and e each independently are an integer of 0 to 4 representing respectively the number of valency of the substituent D and the number of valency of the substituent E; R 1 , R 2 , R 3 , and R 4 each independently represent hydrogen, an optionally substituted alkyl, alkenyl, alkynyl, aralkyl or aryl group having 20 or less carbon atoms, or a group having a heterocyclic ring; and n represents the average number of functional groups, and ranges from 0.80 to 10.0.