Ethylene/Tetrafluoroethylene/fluorinated vinyl monomer copolymer powder and molding method therefor

A method comprising,

• depositing a copolymer powder on a substrate surface, followed by
• heat melting, and
• cooling for solidification to form a coating film having a surface smoothness of at most 0.1 μm as measured by Ra, wherein the copolymer powder comprises polymerized units of ethylene, tetrafluoroethylene and (perfluorobutyl)ethylene,
• wherein the copolymer powder has a viscoelastic property represented by formula (1), wherein the viscosity factor 100 is at most 1×104 Pa·sec, and the anelasticity factor ε represented by formula (2) as the sum of εi in the formula (1) is at most 5×10−4 Pa−1, and which has an average particle diameter of from 5 to 1,000 μm and an apparent density of at least 0.5 g/cc:
• J ⁡ ( t ) = t / ϕ + ∑ i = 1 6 ⁢ ⁢ [ ϵ i ⁡ ( 1 - exp ⁡ ( - t / τ i ) ) ] ( 1 ) ϵ = ∑ i = 1 6 ⁢ ⁢ ϵ i ( 2 )
• wherein the formulae (1) and (2), J(t) is the amount of strain per unit stress under a predetermined stress, φ is a viscosity factor, t is time, μ is an anelasticity factor, i is an integer of from 1 to 6, and τi is a constant wherein τ1=0.1 35 sec, τ2=0.368 sec, τ3=1.000 sec, τ4=2.718 sec, τ5=7.389 sec, τ6=20.086 sec.