Water-soluble or water-dispersible polyisocyanate composition, a process for its preparation and its use in coating compositions

• US 5,468,804 A
• Filed: 09/15/1994
• Issued: 11/21/1995
• Est. Priority Date: 09/23/1993
• Status: Expired due to Term

• Current Assignee: Bayer AG
• Original Assignee: Bayer AG
• Inventors: Brahm, Martin, Probst, Joachim, Schmalstieg, Lutz, Kremer, Wolfgang, Kubitza, Werner
• Primary Examiner(s): Michl, Paul R.
• Assistant Examiner(s): NILAND, PATRICK DENNIS
• Application Number:
  US08/306,335
• Time in Patent Office: 432 Days
• Field of Search: 524/591, 524/839, 428/423.1
• US Class Current: 524/591
• CPC Class Codes: C08G 18/283 Compounds containing ether groups, e.g. oxyalkylated monohydroxy compounds
• CPC Class Codes: C08G 18/706 the liquid medium being water
• CPC Class Codes: C08G 18/8035 Masked aromatic polyisocyanates not provided for in one single of the groups C08G18/8019 and C08G18/8029
• CPC Class Codes: C08G 18/8064 with monohydroxy compounds
• CPC Class Codes: Y10T 428/31551 Of polyamidoester [polyurethane, polyisocyanate, polycarbamate, etc.]

Abstract

A water-dispersible polyisocyanate composition obtained by the partial urethanization of the isocyanate groups of 2,4- and/or 2,6-diisocyanatotoluene with monohydric and polyhydric alcohols, a process for its production, its use as the binder for an aqueous two-component coating composition in combination with a water-soluble or water-dispersible polyhydroxyl component and coatings for water-resistant sheet-form substrates prepared from this coating composition.

Claims

1. A water-dispersible or water-soluble polyisocyanate composition obtained by the partial urethanization of the isocyanate groups of 2,4- and/or 2,6-diisocyanatotoluene by reaction with monohydric and polyhydric alcohols, wherein the polyisocyanate composition has, based on solids,

a) an average NCO functionality of 1.9 to 3.3,

b) a content of isocyanate groups (expressed as NCO, molecular weight 42) of 8 to 18% by weight,

c) a content of ethylene oxide units (expressed as C₂ H₄ O, molecular weight 44) of 5 to 40% by weight which are arranged in terminal polyether chains containing an average of 7 to 25 alkylene oxide units in which at least 70 mol-% of the alkylene oxide units are ethylene oxide units, and

d) a urethane group content (expressed as CHNO₂, molecular weight 59) of 13 to 33% by weight.

2. The water-dispersible polyisocyanate composition of claim 1 which additionally has

e) a content of ether oxygen atoms incorporated through polyhydric ether alcohols of 2 to 16% by weight.

3. A process for the production of a polyisocyanate composition which has

a) an average NCO functionality of 1.9 to 3.3,

b) a content of isocyanate groups (expressed as NCO, molecular weight 42) of 8 to 18% by weight,

c) a content of ethylene oxide units (expressed as C₂ H₄ O, molecular weight 44) of 5 to 40% by weight which are arranged in terminal polyether chains containing an average of 7 to 25 alkylene oxide units in which at least 70 mol-% of the alkylene oxide units are ethylene oxide units, and

d) a urethane group content (expressed as CHNO₂, molecular weight 59) of 13 to 33% by weight,

which comprises reacting at an NCO:

OH equivalent ratio of 4;

1 to 120;

1

A) a polyisocyanate component having an average NCO functionality of 2.7 to 4.1, a content of isocyanate groups of 12 to 20% by weight and a content of urethane groups of 17 to 29% by weight, and containing at least one urethane-modified polyisocyanate produced by partial urethanization of the isocyanate groups of 2,4-and/or 2,6-diisocyanatotoluene with

B) a monofunctional hydrophilic polyether component containing at least one monohydric polyether alcohol containing an average of 7 to 25 alkylene oxide units in which at least 70 mol-% of the alkylene oxide units are ethylene oxide units, to form additional urethane groups.

4. The process of claim 3 wherein polyisocyanate component

A) contains 2 to 16% by weight of ether oxygen atoms incorporated by the reaction of 2,4- and/or 2,6-diisocyanatotoluene with a polyhydric alcohol containing ether groups.

5. The process of claim 3 wherein said monohydric polyether alcohol is prepared by the alkoxylation of a C_1-4 alkanol.

6. The process of claim 4 wherein said monohydric polyether alcohol is prepared by the alkoxylation of a C_1-4 alkanol.

7. An aqueous two-component coating composition wherein the binder contains, in quantities which correspond to an NCO:

OH equivalent ratio of 0.6;

1 to 2;

1,

I) a water-dispersible or water-soluble polyisocyanate composition obtained by the partial urethanization of the isocyanate groups of 2,4- and/or 2,6-diisocyanatotoluene by reaction with monohydric and polyhydric alcohols, wherein the polyisocyanate composition has, based on solids,

a) an average NCO functionality of 1.9 to 3.3,

b) a content of isocyanate groups (expressed as NCO, molecular weight

     42) of 8 to 18% by weight,

c) a content of ethylene oxide units (expressed as C₂ H₄ O, molecular weight

     44) of 5 to 40% by weight which are arranged in terminal polyether chains containing an average of 7 to 25 alkylene oxide units in which at least 70 mol-% of the alkylene oxide units are ethylene oxide units, and

d) a urethane group content (expressed as CHNO₂, molecular weight

     59) of 13 to 33% by weight, and

II) a water-soluble or water-dispersible polyhydroxyl component.

8. The coating composition of claim 7 wherein component II) consists essentially of at least one water-soluble or water-dispersible hydroxy-functional polyacrylate resin having a number average molecular weight of 500 to 50,000.

9. A coated water-resistant, sheet-form substrate which is coated with the coating composition of claim 7.

10. The coating composition of claim 7 wherein the water-dispersible or water-soluble polyisocyanate composition additionally has

e) a content of ether oxygen atoms incorporated through polyhydric ether alcohols of 2 to 16% by weight.

11. The coating composition of claim 8 wherein the water-dispersible or water-soluble polyisocyanate composition additionally has

e) a content of ether oxygen atoms incorporated through polyhydric ether alcohols of 2 to 16% by weight.