Curable aqueous polyurethane dispersions

• US 20030153673A1
• Filed: 12/27/2002
• Published: 08/14/2003
• Est. Priority Date: 06/27/2000
• Status: Active Grant

• Current Assignee: BASF AG (BASF SE)
• Original Assignee: BASF AG (BASF SE)
• Inventors: Vollinger, Frank, Schrof, Wolfgang, Bruchmann, Bernd, Schwalm, Reinhold, Beck, Erich, Meisenburg, Uwe
• Granted Patent: US 7,169,841 B2
• Time in Patent Office: Days
• US Class Current: 524/589
• CPC Class Codes: C08G 18/0823 containing carboxylate salt groups or groups forming them
• CPC Class Codes: C08G 18/7837 containing allophanate groups
• CPC Class Codes: C08G 18/8175 with esters of acrylic or alkylacrylic acid having only one group containing active hydrogen
• CPC Class Codes: C09D 175/16 having terminal carbon-to-carbon unsaturated bonds
• CPC Class Codes: Y10T 428/31551 Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]

Abstract

A curable aqueous polyurethane dispersion substantially comprises

a) at least one compound having two free isocyanate groups, at least one allophanate group and at least one C═C double bond capable of free radical polymerization, a carbonyl group or an oxygen atom in the form of an ether function being bonded directly to the double bond,

b) at least one compound having at least one group reactive toward isocyanate groups and having a C═C double bond capable of free-radical polymerization,

c) if required, at least one compound having at least two groups reactive towards isocyanate groups and selected from hydroxyl, mercapto, primary and/or secondary amino groups,

d) at least one compound having at least one group reactive towards isocyanate groups and having at least one acid group,

e) at least one basic compound for neutralizing or partially neutralizing the acid groups of the compounds d),

and a thermal initiator and is used for coating substrates.

Claims

1. A curable aqueous polyurethane dispersion comprising

a) at least one compound having at least two free isocyanate groups, at least one allophanate group and at least one C═

C double bond capable of free radical polymerization, a carbonyl group or an oxygen atom in the form of an ether function being bonded directly to the double bond,

b) at least one compound having at least one group reactive toward isocyanate groups and having a C═

C double bond capable of free-radical polymerization,

c) if required, at least one compound having at least two groups reactive toward isocyanate groups and selected from hydroxyl, mercapto, primary and/or secondary amino groups,

d) at least one compound having at least one group reactive toward isocyanate groups and having at least one acid group,

e) at least one basic compound for neutralizing or partially neutralizing the acid groups of the compounds d),

f) if required, at least one compound differing from b), d) and e) and having only one group reactive toward isocyanate groups,

g) if required, at least one polyisocyanate differing from a),

h) at least one thermal initiator,

i) if required, further additives which are selected from reactive diluents, photoinitiators and conventional coating additives, and

k) water.

2. A dispersion as claimed in claim 1, wherein the component a) is selected from compounds of the formula I

OCN—

R¹

R²—

C(O)—

R²—

R¹

_nNCO  

 

(I)

where

n is an integer from 1 to 10,

R¹ is a divalent aliphatic or alicylic C₂- to C₂₀-hydrocarbon unit or an aromatic C₆- to C₂₀-hydrocarbon unit,

R² in each repeating unit is —

NH—

on the one hand and, on the other hand,

R³ being a radical derived from an alcohol A by abstraction of the H atom from the alcoholic hydroxyl group, the alcohol A additionally having at least one C═

C double bond capable of free-radical polymerization and a carbonyl group or an oxygen atom being bonded by an ether bond directly to the double bond.

3. A dispersion as claimed in any of the preceding claims, wherein the thermal initiator h) has a half-life at 60°

C. of at least one hour.

4. A dispersion as claimed in any of the preceding claims, wherein the component h) comprises at least one compound which has at least one group reactive toward isocyanate groups and is capable of liberating free radicals thermally even after reaction with a compound containing isocyanate groups.

5. A dispersion as claimed in any of the preceding claims, wherein the component h) comprises benzopinacol or a derivative thereof.

6. A dispersion as claimed in any of the preceding claims, wherein the component h) comprises an (arylsulfonyl) acetic acid alkyl ester.

7. A dispersion as claimed in any of the preceding claims, wherein the isocyanate groups of the compounds of component a) and, if present, g) are reacted to an extent of

from 5 to 98, preferably from 10 to 80, mol % with groups of at least one compound of component b) which are reactive toward isocyanate groups,

from 0 to 70, preferably from 20 to 60, mol % with groups of at least one compound of component c) which are reactive toward isocyanate groups,

from 2 to 10, preferably from 4 to 8, mol % with groups of at least one compound of component d) which are reactive toward isocyanate groups.

8. A process for coating articles, wherein

i) an article is coated with a dispersion as claimed in any of claims 1 to 7,

ii) volatile components of the dispersion are removed for film formation under conditions under which the thermal initiator h) substantially still forms no free radicals,

iii) if required, the film formed in step ii) is exposed to high-energy radiation, the film being precured, and then, if required, the article coated with the precured film being mechanically processed or the surface of the precured film being brought into contact with another article, and

iv) the film is subjected to thermal final curing.

9. A coated article obtainable by a process as claimed in claim 8.

10. The use of a dispersion as claimed in any of claims 1 to 7 for coating substrates of metal, wood, paper, ceramic, glass, plastics, textile, leather, nonwovens or mineral building materials.

11. The use of a dispersion as claimed in any of claims 1 to 7 as or in exterior coatings, preferably of buildings or parts of buildings, road markings or coatings on vehicles and aircraft.

12. The use as claimed in claim 11 as or in automotive clear-coat(s).