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US 2016/0237310 A1Published application
New crosslinkers for coating compounds
AssigneeBASF SE
InventorFrederic LUCAS
Life of this patent
Estimating the term…
Abstract
The present invention describes new crosslinkers for coating compositions, their preparation, and their use.
Claims17
1:
- A polyurethane obtainable by reaction of
- (A) at least one aliphatic or cycloaliphatic di- or polyisocyanate,
- (B) at least one compound having at least one isocyanate-reactive group and at least one epoxy group, and
- (C) at least one blocking agent comprising a group which is reactive both toward an isocyanate group and toward an epoxy group.
1 more element
2:
- The polyurethane according to claim 1, wherein the compound (C) is selected from the group consisting of
- secondary amines,
- lactams,
- oximes,
- pyrazoles,
- triazoles, and
- 1,3-dicarbonyl compounds.
4 more elements
3:
- The polyurethane according to claim 1, wherein the compound (A) is selected from the group consisting of isophorone diisocyanate, 2,4′-di(isocyanatocyclohexyl)methane, 4,4′-di(isocyanatocyclohexyl)methane, and mixtures thereof.
4:
- The polyurethane according to claim 1, wherein the compound (A) is selected from the group consisting of
- polyisocyanates comprising isocyanurate groups and 1,6-hexamethylene diisocyanate and/or isophorone diisocyanate, and
- polyisocyanates comprising biuret groups and 1,6-hexamethylene diisocyanate.
5:
- The polyurethane according to claim 4, which has formula (II)
- wherein
- R1 at each occurrence is 1,6-hexylene,
- and
- Z1, Z2, and Z3 in each case independently of one another are selected from the group consisting of
- a free isocyanate group (—NCO),
- a blocked isocyanate group, and
- a group of formula (III)
- wherein
- X is oxygen (O) or sulfur (S),
- n is a positive integer from 1 to 3,
- R2 is an (n+1)-valent spacer comprising 1 to 10 atoms and/or groups of atoms, and
- at least one of the groups Z1 to Z3 is a blocked isocyanate group, and at least one of the groups Z1 to Z3 is a group of the formula (III).
10 more elements
6:
- The polyurethane according to claim 4, which has formula (IV)
- wherein
- Block is a radical of a blocking agent (C) from which a hydrogen atom has been abstracted,
- X is oxygen (O) or sulfur (S),
- R1 at each occurrence is 1,6-hexylene,
- n is a positive integer from 1 to 3,
- R2 is an (n+1)-valent spacer comprising 1 to 10 atoms and/or groups of atoms.
4 more elements
7:
- The polyurethane according to claim 4, which has formula (V)
- wherein
- Block is a radical of a blocking agent (C) from which a hydrogen atom has been abstracted,
- X is oxygen (O) or sulfur (S),
- R1 at each occurrence is 1,6-hexylene,
- n is a positive integer from 1 to 3, and
- R2 is an (n+1)-valent spacer comprising 1 to 10 atoms and/or groups of atoms.
4 more elements
8:
- The polyurethane according to claim 1, which has an NCO content of less than 7 wt % (calculated with a molar weight of 42 g/mol).
9:
- A coating composition comprising
- at least one polyurethane according to claim 1;
- optionally a solvent;
- optionally typical coatings additives;
- and
- optionally at least one catalyst.
3 more elements
10:
- The coating composition according to claim 9, wherein the catalyst comprises dibutyltin dilaurate, dioctyltin dilaurate, zinc(II) diacetate, zinc(II) dioctoate, zirconium acetylacetonate, zirconium 2,2,6,6-tetramethyl-3,5-heptanedionate, or bismuth compounds.
11:
- A process for preparing a polyurethane according to claim 1, which comprises first subjecting at least one di- or polyisocyanate (A) to partial reaction with at least one blocking agent (C) and subsequently subjecting the remaining free isocyanate groups to at least partial reaction with at least one compound (B).
12:
- A process for producing a polyurethane coating, which comprises applying at least one polyurethane according to claim 1, optionally mixed with at least one further polyisocyanate different from the polyurethane, to a substrate, and heating to a temperature at which at least some of the blocked isocyanate groups are cleaved significantly into free isocyanate groups and free blocking agent (C).
13:
- A one-component coating composition, comprising a polyurethane according to claim 1.
14:
- The polyurethane according to claim 1, wherein the compound (B) has precisely one isocyanate-reactive group.
15:
- The polyurethane according to claim 2, wherein the compound (C) is selected from the group consisting of:
- a secondary amine selected from the group consisting of cyclic secondary amines, di-C1-C10-alkylamines and di-C6-C12-cycloalkylamines;
- a lactam selected from the group consisting of 2-pyrrolidone and caprolactam;
- an oxime selected from the group consisting of oximes of methyl n-amyl ketone, methyl isoamyl ketone, methyl 3 ethylheptyl ketone, methyl 2,4-dimethylpentyl ketone, butanone (methyl ethyl ketone), cyclohexanone, methyl isopropyl ketone, methyl isobutyl ketone, diisobutyl ketone, methyl tert-butyl ketone, diisopropyl ketone and 2,2,6,6-tetramethylcyclohexanone;
- 3,5-dimethylpyrazole;
- 1,2,4-trizoles;
- and
- 1,3-dicarbonyl compounds selected from the group consisting of acetylacetone, malonic di-C1-C10 alkyl esters and acetoacetic C1-C10 alkyl esters.
5 more elements
16:
- The polyurethane according to claim 5, wherein R1 at each occurrence is 1,6-hexylene, and n is 1.
17:
- The polyurethane according to claim 6, wherein R1 at each occurrence is 1,6-hexylene, and n is 1.