LOW-VISCOSITY POLYURETHANE ACRYLATE DISPERSIONS

• US 20120259065A1
• Filed: 12/13/2010
• Published: 10/11/2012
• Est. Priority Date: 12/19/2009
• Status: Active Grant

• Current Assignee: Bayer Materialscience AG (Covestro AG)
• Original Assignee: Bayer Intellectual Property GmbH (Bayer AG)
• Inventors: Sommer, Stefan, Rische, Thorsten, Luehmann, Erhard
• Granted Patent: US 9,567,423 B2
• Time in Patent Office: Days
• US Class Current: 524/591
• CPC Class Codes: C08G 18/0823 containing carboxylate salt groups or groups forming them
• CPC Class Codes: C08G 18/0866 the dispersing or dispersed phase being an aqueous medium
• CPC Class Codes: C08G 18/12 using two or more compounds having active hydrogen in the first polymerisation step
• CPC Class Codes: C08G 18/6225 Polymers of esters of acrylic or methacrylic acid
• CPC Class Codes: C08G 18/6229 Polymers of hydroxy groups containing esters of acrylic or methacrylic acid with aliphatic polyalcohols
• CPC Class Codes: C08G 18/6705 Unsaturated polymers not provided for in the groups C08G18/671, C08G18/6795, C08G18/68 or C08G18/69
• CPC Class Codes: C08G 18/672 Esters of acrylic or alkyl acrylic acid having only one group containing active hydrogen
• CPC Class Codes: C08G 18/6795 Unsaturated polyethers
• CPC Class Codes: C08G 18/68 Unsaturated polyesters
• CPC Class Codes: C08G 18/73 acyclic
• CPC Class Codes: C08G 18/755 and at least one isocyanate or isothiocyanate group linked to a secondary carbon atom of the cycloaliphatic ring, e.g. isophorone diisocyanate
• CPC Class Codes: C08G 18/758 containing two or more cycloaliphatic rings

Abstract

The present invention relates to a process for the preparation of low-viscosity, radiation-curable, aqueous dispersions based on polyurethane acrylates (UV-PUDs), wherein the UV-PUDs hydrophilised via hydroxy-functionalised carboxylic acids have a lower initial viscosity when a large part of the urethanisation, that is to say the reaction of the NCO-functionalised compounds with the OH-functionalised compounds, initially takes place in the absence of the acid-carrying compounds and the incorporation of the acid-carrying compounds via their hydroxyl function takes place as late as possible.

Claims

1-8. -8. (canceled)

9. A process for preparing a radiation-curable, aqueous dispersion based on a polyurethane acrylate (i) comprising as structural components

A) one or more polymeric compounds selected from the group consisting of polyester (meth)acrylates, polyether (meth)acrylates, polyether ester (meth)acrylates, unsaturated polyesters having allyl ether structural units, and polyepoxy (meth)acrylates having an OH number in the range from 15 to 300 mg KOH/g of substance;

B) optionally one or more monomeric compounds other than A) comprising a hydroxy function and at least one (meth)acrylate group;

C) one or more compounds other than A) or B) comprising at least one group reactive towards isocyanate;

D) one or more organic polyisocyanates;

E) one or more compounds comprising at least one hydroxy function and, in addition, at least one carboxylic acid or carboxylate function, wherein said compounds have a dispersing action for the polyurethane dispersion;

F) compounds other than A) to E) comprising at least one group reactive towards isocyanate;

wherein components A) through D) are reacted in a first reaction step to form a polyurethane acrylate which comprises neither ionic nor potentially ionic groups and, after determination of the NCO content, an NCO value is reached which can differ from the theoretical NCO content by up to 1.5 wt. % NCO (absolute); and

in a second reaction step, component E) is reacted with any free NCO groups from the reaction product of components A) to D) and, after again determining the NCO content, an NCO value is reached which can differ from the theoretical NCO value by up to 1.5 wt. % NCO (absolute); and

in a third reaction step, component F) is reacted with any free NCO groups.

10. The process of claim 9, wherein one or more reactive diluents comprising at least one radically polymerizable group, component (ii), are added.

11. The process of claim 9, wherein component E) is selected from the group consisting of dimethylolpropionic acid, dimethylolbutyric acid, hydroxypivalic acid, malic acid, citric acid, glycolic acid, and lactic acid.

12. The process of claim 9, wherein the molar ratios of isocyanate groups in D) to groups reactive towards isocyanates in A) through C) are from 1.2:

1.0 to 4.0;

1.0.

13. The process of claim 9, wherein the molar ratios of isocyanate groups in D) to groups reactive towards isocyanates in A), B), C) and E) are from 1.05:

1.0 to 2.5;

1.0.

14. The process of claim 9, wherein, after the first reaction step, after determination of the NCO content, an NCO value is reached which can differ from the theoretical NCO value by up to 1.0 wt. % NCO (absolute), and after the second reaction step, after determination of the NCO content, an NCO value is reached which can differ from the theoretical NCO value by up to 1.0 wt. % NCO (absolute).

15. A radiation-curable, aqueous dispersion based on a polyurethane acrylate (i) prepared by the process of claim 9.

16. A coating, lacquer, or adhesive comprising the radiation-curable, aqueous dispersion based on a polyurethane acrylate (i) of claim 15.