Coating compositions and coatings produced from them and featuring high scratch resistance in association with good results in the Erichsen cupping test and good antistonechip properties
The present invention relates to coating compositions comprising (A) at least one hydroxyl-containing polyacrylate and/or at least one hydroxyl-containing polymethacrylate and (B) at least one compound containing isocyanate groups and having at least one structural unit (I) of the formula (I) —NR—(X—SiR″ x (OR′)3- x ) (I), and having at least one structural unit (II) of the formula (II) —N(X—SiR″ x (OR′)3- x ) n (X′—SiR″ y (OR′)3- y ) m (II), where (i) (A) has a glass transition temperature of less than 10° C., (ii) (B) contains more than 10 to more than 90 mol %, of at least one structural unit of the formula (I) and 10 to less than 90 mol % of at least one structural (II), based on the entirety of the structural units (I) and (II), and (iii) 10 to 60 mol % of the isocyanate groups of the diisocyanate and/or polyisocyanate parent structure of (I) and (II). The invention provides multistage coating processes using these coating compositions.
1. A coating composition comprising:
(A) at least one hydroxyl-containing polyacrylate and/or at least one hydroxyl-containing polymethacrylate, and
(B) at least one compound containing isocyanate groups and having at least one structural unit (I) of the formula (I)
—N(X—SiR″ x (OR′)3- x ) (I),
and having at least one structural unit (II) of the formula (II)
—N(X—SiR″ x (OR′)3- x ) n (X′—SiR″ y (OR′)3- y ) m (II),
where
R=hydrogen, an alkyl group, an cycloalkyl group, an aryl group, or an aralkyl group, wherein the alkyl group, the cycloalkyl group, the aryl group, and the aralkyl group include a carbon chain that is interruptible by nonadjacent oxygen, sulfur, or NRa groups, with Ra=an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group,
R′=hydrogen, an alkyl group, or a cycloalkyl group, wherein the alkyl group and the cycloaklyl group include a carbon chain interruptible by nonadjacent oxygen, sulfur, or NRa groups, with Ra=an alkyl group, an cycloalkyl group, an aryl group, or an aralkyl group,
X, X′=a linear and/or branched alkylene or cycloalkylene radical having from 1 carbon atom to 20 carbon atoms,
R″=an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, wherein the alkyl group, the cycloalkyl group, the aryl group, and the aralkyl group include a carbon chain interruptible by nonadjacent oxygen, sulfur, or NRa groups, with Ra=an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group,
n=0 to 2,
m=0 to 2,
m+n=2,
x=0 to 2, and
y=0 to 2,
wherein
(i) the at least one hydroxyl-containing polyacrylate (A) and/or at least one hydroxyl-containing polymethacrylate have/has a glass transition temperature of less than 10° C.,
(ii) the at least one compound (B) containing isocyanate groups contains from more than 10 mol % to 90 mol % of the at least one structural unit (I) and from 10 mol % to less than 90 mol % of the at least one structural unit (II), based on an entirety of the structural units (I) and (II), and
(iii) from 10 mol % to 60 mol % of the isocyanate groups of the at least one compound (B) containing isocyanate groups have been reacted to form the structural units (I) and (II).
2. The coating composition as claimed in claim 1 , wherein
R′=an ethyl group and/or a methyl group, and/or
X, X′=an alkylene radical having from 1 carbon atom to 4 carbon atoms, and/or
R″=an alkyl radical.
3. The coating composition as claimed in claim 1 , wherein
R″=an alkyl radical having from 1 carbon atom to 6 carbon atoms.
4. The coating composition as claimed in claim 1 , wherein the at least one hydroxyl-containing polyacrylate (A) and/or at least one hydroxyl-containing polymethacrylate have/has a glass transition temperature, Tg, of from −60° C. to 5° C.
5. The coating composition as claimed in claim 1 , wherein the at least one hydroxyl-containing polyacrylate (A) and/or at least one hydroxyl-containing polymethacrylate have/has a glass transition temperature, Tg, of from −30° C. to less than 0° C.
6. The coating composition as claimed in claim 1 , wherein the at least one compound (B) containing isocyanate groups contains from 20 mol % to 80 mol % of the at least one structural unit (I) and from 20 mol % to 80 mol % of at least one structural unit (II), based on the entirety of the structural units (I) and (II).
7. The coating composition as claimed in claim 1 , wherein the at least one compound (B) containing isocyanate groups contains from 30 mol % to 70 mol % of the at least one structural unit (I) and from 30 mol % to 70 mol % of the at least one structural unit (II), based on the entirety of the structural units (I) and (II).
8. The coating composition as claimed in claim 1 , wherein the coating composition has a calculated silicon content of 1.5% by mass Si to 6.0% by mass Si based on a solids content of the coating composition.
9. The coating composition as claimed in claim 1 , wherein the compound (B) containing isocyanate groups has a parent structure formed from a diisocyanate and/or a polyisocyanate having a glass transition temperature of less than or equal to 0° C.
10. The coating composition as claimed in claim 9 , wherein the diisocyanate and/or the polyisocyanate are/is 1,6-hexamethylene diisocyanate and/or the isocyanurate trimers thereof and/or the allophanate dimers thereof.
11. The coating composition as claimed in claim 1 , wherein the at least one compound (B) containing isocyanate groups has been prepared by reacting diisocyanates and/or polyisocyanates with at least one compound of the formula (Ia)
H—NR—(X—SiR″ x (OR′)3- x ) (Ia)
and with at least one compound of the formula (IIa)
HN(X—SiR′ x (OR′)3- x ) n (X′—SiR″ y (OR′)3- y ) m (IIa),
where
R=hydrogen, an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, wherein the alkyl group, the cycloalkyl group, the aryl group, and the aralkyl group include a carbon chain interruptible by nonadjacent oxygen, sulfur, or NRa groups, with Ra=an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group,
R′=hydrogen, an alkyl group, or a cycloalkyl group, wherein the alkyl group and the cycloalkyl group include a carbon chain interruptible by nonadjacent oxygen, sulfur, or NRa groups, with Ra=an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group,
X, X′=a linear and/or branched alkylene or cycloalkylene radical having from 1 carbon atom to 20 carbon atoms,
R″=an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group, wherein the alkyl group, the cycloalkyl group, the aryl group, and the aralkyl group include a carbon chain interruptible by nonadjacent oxygen, sulfur, or NRa groups, with Ra=an alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group,
n=0 to 2
m=0 to 2,
m+n=2,
x=0 to 2, and
y=0 to 2.
12. The coating composition as claimed in claim 1 , wherein the at least one hydroxyl-containing polyacrylate (A) and/or at least one hydroxyl-containing polymethacrylate is present in the coating composition in an amount of from 20% by weight to 80% by weight based on a solids content of the coating composition.
13. The coating composition as claimed in claim 1 , wherein the at least one hydroxyl-containing polyacrylate (A) and/or at least one hydroxyl-containing polymethacrylate is obtained by copolymerizing:
(a) from 10% by weight to 80% by weight of a hydroxyl-containing ester of acrylic acid or a mixture thereof,
(b) from 0% by weight to 30% by weight of a hydroxyl-containing ester of methacrylic acid other than (a) or a mixture thereof,
(c) from 5% by weight to 90% by weight of an aliphatic or cycloaliphatic ester of (meth)acrylic acid other than (a) and (b) having at least 4 carbon atoms in an alcohol residue or a mixture thereof,
(d) from 0% by weight to 5% by weight of an ethylenically unsaturated carboxylic acid or a mixture thereof,
(e) from 0% by weight to 50% by weight of a vinylaromatic or a mixture thereof, and
(f) from 0% by weight to 50% by weight of an ethylenically unsaturated monomer other than (a), (b), (c), (d), and (e) or a mixture thereof,
wherein a sum of the weight fractions of components (a), (b), (c), (d), (e) and (f) is 100% by weight.
14. The coating composition as claimed in claim 1 , further comprising at least one catalyst formed from phosphorus and nitrogen.
15. The coating composition as claimed in claim 1 , wherein the at least one hydroxyl-containing polyacrylate (A) and/or at least one hydroxyl-containing polymethacrylate has a glass transition temperature, Tg, of from −27° C. to −6° C.
16. The coating composition as claimed in claim 1 , wherein the at least one compound (B) containing isocyanate groups comprises at least one water scavenger formed from an orthoformic acid trialkyl ester.
17. A multicoat color and/or effect paint system comprising:
at least one pigmented basecoat, and
at least one clearcoat disposed on the at least one pigmented basecoat and formed from a coating composition as claimed in claim 1 .
18. A multistage coating process, comprising:
applying a pigmented basecoat to an uncoated or precoated substrate, and after applying the pigmented basecoat, applying the coating composition as claimed in claim 1 to the pigmented basecoat.
19. The multistage coating process as claimed in claim 18 , further comprising:
after applying the pigmented basecoat, first drying the pigmented basecoat at a temperature of from room temperature to 80° C., and
after applying the coating composition, curing the coating composition at a temperature of from 30° C. to 200° C. for a time of from one minute to 10 hours.
20. The multistage coating process as claimed in claim 18 , wherein the multistage coating process is carried out in automotive OEM finishing, finishing of surface-mounted automotive components, or automotive refinishing.