Powder coating material, method for producing substrate provided with coating film, coated article and fluorinated polymer

A fluorinated polymer, comprising a fluoroolefin unit, a monomer unit of formula (1) and a monomer unit of formula (2),

• wherein the content of the monomer unit of formula (2) is from 5 to 20 mol % to all units in the fluorinated polymer, and
• the fluorinated polymer has a weight average molecular weight of from 15,000 to 75,000:
• X—Z formula (1):
• CHR21═CR22(CH2)nCOOH formula (2):
• wherein X is CH2═CHC(O)O—, CH2═C(CH3)C(O)O—, CH2═CHOC(O)—, CH2═CHCH2OC(O)—, CH2═CHO— or CH2═CHCH2O—,
• Z is a C4-8 alkyl group represented by the formula —C(Z1)3, a C6-10 cycloalkyl group, a C6-10 cycloalkylalkyl group, a C6-10 aryl group or a C7-12 aralkyl group, provided that three Z1's are each independently a C1-5 alkyl group, and the total number of carbon atoms of the three Z1's is an integer of from 3 to 7,
• R21 and R22 are each independently a hydrogen atom or a C1-3 alkyl group, and
• n is an integer of from 0 to 12.

A fluorinated polymer, comprising a fluoroolefin unit, a monomer unit of formula (1) and a monomer unit of represented by the following formula (2),

• wherein the content of the monomer unit of formula (2) is from 5 to 20 mol % to all units in the fluorinated polymer, and
• the fluorinated polymer has a melt viscosity at 170° C. of from 20 to 100 Pa·s:
• X—Z formula (1):
• CHR21═CR22(CH2)nCOOH formula (2):
• wherein X is CH2═CHC(O)O—, CH2═C(CH3)C(O)O—, CH2═CHOC(O)—, CH2═CHCH2OC(O)—, CH2═CHO— or CH2═CHCH2O—,
• Z is a C4-8 alkyl group represented by the formula —C(Z1)3, a C6-10 cycloalkyl group, a C6-10 cycloalkylalkyl group, a C6-10 aryl group or a C7-12 aralkyl group, provided that three Z1's are each independently a C1-5 alkyl group, and the total number of carbon atoms of the three Z1's is an integer of from 3 to 7,
• R21 and R22 are each independently a hydrogen atom or a C1-3 alkyl group, and
• n is an integer of from 0 to 12.