Intermediate coating composition, multilayered coating film, and method for forming the multilayered coating film
View Patent ↗An intermediate coating composition used in forming an intermediate coating layer directly overlaid on a surface of an electrodeposition coating layer constructing a vehicle outer panel, the coating composition containing as resin components: (a) 1% to 27% by mass of a polycaprolactonetriol; (b) 20% to 60% by mass of a blocked isocyanate; and (c) 1% to 20% by mass of a melamine resin, each at a percentage content in entire resin components, and the coating composition further containing as a pigment component: (d) 1% to 10% by mass of talc in terms of pigment mass concentration. As the resin component, (e) greater than 0% to 10% by mass of an epoxy resin is preferably contained. A urethane curing catalyst is preferably contained in an amount of greater than 0.01 parts to 2 parts by mass with respect to 100 parts by mass of the entire resin components.
1. An intermediate coating composition for forming an intermediate coating layer directly on a surface of an electrodeposition coating layer of a vehicle outer panel,
the intermediate coating composition comprising resin components and a pigment component,
the resin components comprising:
(a) a polycaprolactonetriol in an amount of no less than 1% by mass and no greater than 15% by mass;
(b) a blocked isocyanate in an amount of no less than 20% by mass and no greater than 60% by mass; and
(c) a melamine resin in an amount of no less than 1% by mass and no greater than 20% by mass,
each at a percentage content in entire resin components, and
the pigment component comprising:
(d) talc in an amount of no less than 1% by mass and no greater than 10% by mass in terms of pigment mass concentration.
2. The intermediate coating composition according to claim 1 , further comprising (e) an epoxy resin as the resin component in an amount of greater than 0% by mass and no greater than 10% by mass at the percentage content in the entire resin components.
3. The intermediate coating composition according to claim 1 , further comprising (g) a urethane curing catalyst in an amount of greater than 0.01 parts by mass and no greater than 2 parts by mass with respect to 100 parts by mass of the entire resin components.
4. The intermediate coating composition according to claim 1 , wherein the amount of the polycaprolactonetriol is no less than 5% by mass and no greater than 10% by mass at the percentage content in the entire resin components.
5. The intermediate coating composition according to claim 1 , wherein the amount of the polycaprolactonetriol is no less than 5% by mass and no greater than 10% by mass, the amount of the blocked isocyanate is no less than 25% by mass and no greater than 40% by mass, and the amount of the melamine resin is no less than 2.5% by mass and no greater than 15% by mass, each at the percentage content in the entire resin components, and the amount of the talc is no less than 2% by mass and no greater than 4.5% by mass in terms of pigment mass concentration.
6. The intermediate coating composition according to claim 1 , wherein a mean particle size of the talc is no less than 1 μm and no greater than 10 μm.
7. A multilayered coating film comprising:
an electrodeposition coating layer of a vehicle outer panel;
an intermediate coating layer directly on a surface of the electrodeposition coating layer; and
a top coating layer on a surface of the intermediate coating layer, wherein
the intermediate coating layer is a cured product of the intermediate coating composition according to claim 1 .
8. The multilayered coating film according to claim 7 , wherein the intermediate coating composition further comprises (e) an epoxy resin as the resin component in an amount of greater than 0% by mass and no greater than 10% by mass at the percentage content in the entire resin components.
9. The multilayered coating film according to claim 7 , wherein the intermediate coating composition further comprises (g) a urethane curing catalyst in an amount of greater than 0.01 parts by mass and no greater than 2 parts by mass with respect to 100 parts by mass of the entire resin components.
10. The multilayered coating film according to claim 7 , wherein the amount of the polycaprolactonetriol in the intermediate coating composition is no less than 5% by mass and no greater than 10% by mass at the percentage content in the entire resin components.
11. The multilayered coating film according to claim 7 , wherein in the intermediate coating composition, the amount of the polycaprolactonetriol is no less than 5% by mass and no greater than 10% by mass, the amount of the blocked isocyanate is no less than 25% by mass and no greater than 40% by mass, and the amount of the melamine resin is no less than 2.5% by mass and no greater than 15% by mass, each at the percentage content in the entire resin components, and the amount of the talc is no less than 2% by mass and no greater than 4.5% by mass in terms of pigment mass concentration.
12. The multilayered coating film according to claim 7 , wherein a mean particle size of the talc in the intermediate coating composition is no less than 1 μm and no greater than 10 μm.
13. A multilayered coating film-forming method comprising:
forming an electrodeposition coating layer of a vehicle outer panel;
forming an intermediate layer by applying the intermediate coating composition of claim 1 on a surface of the electrodeposition coating layer; and
forming a top coating layer on a surface of the intermediate coating layer.
14. The multilayered coating film-forming method according to claim 13 , wherein the intermediate coating composition further comprises (e) an epoxy resin as the resin component in an amount of greater than 0% by mass and no greater than 10% by mass at the percentage content in the entire resin components.
15. The multilayered coating film-forming method according to claim 13 , wherein the intermediate coating composition further comprises (g) a urethane curing catalyst in an amount of greater than 0.01 parts by mass and no greater than 2 parts by mass with respect to 100 parts by mass of the entire resin components.
16. The multilayered coating film-forming method according to claim 13 , wherein the amount of the polycaprolactonetriol in the intermediate coating composition is no less than 5% by mass and no greater than 10% by mass at the percentage content in the entire resin components.
17. The multilayered coating film-forming method according to claim 13 , wherein in the intermediate coating composition, the amount of the polycaprolactonetriol is no less than 5% by mass and no greater than 10% by mass, the amount of the blocked isocyanate is no less than 25% by mass and no greater than 40% by mass, and the amount of the melamine resin is no less than 2.5% by mass and no greater than 15% by mass, each at the percentage content in the entire resin components, and the amount of the talc is no less than 2% by mass and no greater than 4.5% by mass in terms of pigment mass concentration.
18. The multilayered coating film-forming method according to claim 13 , wherein a mean particle size of the talc in the intermediate coating composition is no less than 1 μm and no greater than 10 μm.