Solid siliconized polyester resin for powder coating

A coating composition comprising a solid silicone polyester having a Tg between 35° C. to 75° C., and a solid crosslinker;

• wherein the silicone comprises a silanol-functional organopolysiloxane resin which contains at least one or more of the repeating units having the formulae:
• R
• a
• 1
• ⁢
• R
• b
• 2
• ⁢
• SiO
• 1
• 2
• ⁡
• (
• M
• ⁢
• ⁢
• units
• )
• R
• a
• 1
• ⁢
• R
• b
• 2
• ⁢
• SiO
• 2
• 2
• ⁡
• (
• D
• ⁢
• ⁢
• units
• )
• R
• a
• 1
• ⁢
• R
• b
• 2
• ⁢
• SiO
• 3
• 2
• ⁡
• (
• T
• ⁢
• ⁢
• units
• )
• SiO
• 4
• 2
• ⁡
• (
• Q
• ⁢
• ⁢
• units
• )
• wherein
• R1 and R2 are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatom linking group such as, but not limited to,
• a is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2;
• b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2;
• and
• in M units, a+B+C=2;
• in D units, a+b+c=2,
• in T units, a+b+c=1;
• and
• wherein the organopolysiloxane rein comprises 0 to 10 mole percent D units, based on the total number of moles of the organopolysiloxane resin and 75 to 100 mole percent T units, based on the total number of moles of the organopolysiloxane resin, and wherein the silicone polyester has a hydroxy equivalent weight of 140-2244 g/mole OH and a hydroxyl number of 200-300.

A solid silicone polyester suitable for use as a powder coating, said silicone polyester prepared by reacting a silicone with a polyester, the resulting silicone polyester having a Tg between 35° C. and 50° C.;

• and
• wherein the silicone comprises a silanol-functional organopolysiloxane resin which contains at least one or more of the repeating units having the formulae:
• R
• a
• 1
• ⁢
• R
• b
• 2
• ⁢
• SiO
• 1
• 2
• ⁡
• (
• M
• ⁢
• ⁢
• units
• )
• R
• a
• 1
• ⁢
• R
• b
• 2
• ⁢
• SiO
• 2
• 2
• ⁡
• (
• D
• ⁢
• ⁢
• units
• )
• R
• a
• 1
• ⁢
• R
• b
• 2
• ⁢
• SiO
• 3
• 2
• ⁡
• (
• T
• ⁢
• ⁢
• units
• )
• SiO
• 4
• 2
• ⁡
• (
• Q
• ⁢
• ⁢
• units
• )
• wherein
• R1 and R2 are independently a C1-20 hydrocarbon, optionally interspersed with a heteroatom linking group such as, but not limited to,
• a is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2;
• b is an integer of 0, 1, 2 or 3, preferably 0, 1, or 2;
• and
• in M units, a+b+c=3, and
• in D units, a+b+c=2, and
• in T units, a+b+c=1;
• and
• wherein the organopolysiloxane resin comprises 95 mole percent T units and 5 mole percent D units, based on the total number of moles of the organopolysiloxane resin.