Radiation curable aqueous compositions

Abstract

Radiation curable aqueous compositions (I) with reduced photo-yellowing are provided. Said composition comprises water, at least one ethylenically unsaturated compound and at least one carboxylic acid hydrazide-containing compound (H) in an amount sufficient to reduce photo-yellowing. Materials of the invention have the advantage that they help to reduce photo-yellowing. They may have a beneficial effect on long term yellowing caused by weathering too. Compositions (I) of the invention allow a better quality control of products and materials just after cure. Materials of the invention can be used to make coatings, inks, paints, varnishes and adhesives and they are further suitable for the making of composites, gel coats, 3D-curing and the making of 3D-objects in general.

Claims

1. A radiation curable aqueous composition (I) with reduced photo-yellowing, said composition comprising water, and at least one saturated carboxylic acid hydrazide-containing compound (H1) and at least one ethylenically unsaturated compound (EC) and/or at least one ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2), wherein the saturated carboxylic acid hydrazide-containing compound (H1) is prepared from: (i) at least one compound containing free isocyanate groups, and (iv) at least one carboxylic acid hydrazide compound, wherein the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2) is prepared from: (i) at least one compound containing free isocyanate groups, (ii) at least one ethylenically unsaturated compound containing at least one group capable of reacting with an isocyanate and further at least one ethylenically unsaturated group, and (iv) at least one carboxylic acid hydrazide compound, and wherein the amount of carboxylic acid hydrazides compound (iv) used for the synthesis of the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2) or the saturated carboxylic acid hydrazide-containing compound (H1), expressed in % wt of active —NH—NH— groups relative to the total weight of compounds (H2), (H1), and (EC) is higher than 0.2 wt %, thereby forming a carboxylic acid hydrazide-containing compound (H) containing at least one —C(═O)NH—NH—C(═O)—NH— linkage.

2. The radiation curable aqueous composition (I) of claim 1, wherein the carboxylic acid hydrazide-containing compound (H) is provided in the form of an additive and/or in the form of a polymeric resin that, optionally, contains one or more ethylenically unsaturated groups.

3. The radiation curable aqueous composition (I) of claim 1, wherein the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2) comprises one or more compounds (A1) that is prepared from: (i) at least one compound containing free isocyanate groups, (ii) at least one ethylenically unsaturated compound containing at least one group capable of reacting with an isocyanate and further at least one ethylenically unsaturated group, (iii-1) at least one compound containing at least one group capable of reacting with isocyanate groups and further at least one hydrophilic group capable of rendering the compound (A) dispersible or soluble in water either directly or after the reaction with a neutralizing agent to provide a salt, (iv) at least one carboxylic acid hydrazide compound, and (v) optionally, at least one compound containing at least one group capable of reacting with isocyanate groups but no ethylenically unsaturated groups.

4. The radiation curable aqueous composition (I) of claim 1, wherein the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2) comprises one or more compounds (A2) that is prepared from: (iv) at least one compound containing at least two free isocyanate groups, (v) at least one ethylenically unsaturated compound containing at least one group capable of reacting with an isocyanate and further at least one ethylenically unsaturated group, (iii-2) at least one polymer of a weight average molecular weight (Mw) higher than 2,000 containing at least one group capable of reacting with isocyanate groups and further at least one hydrophilic group capable of rendering the compound (A) dispersible or soluble in water either directly or after the reaction with a neutralizing agent to provide a salt, and (iv) at least one carboxylic acid hydrazide compound.

5. The radiation curable aqueous composition (I) of claim 1, wherein the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2) comprises one or more compounds (A3) that is prepared from: (iv) at least one compound containing free isocyanate groups, (vii) at least one ethylenically unsaturated compound containing at least one group capable of reacting with an isocyanate and further at least one ethylenically unsaturated group, (vii) optionally, at least one compound containing one group capable of reacting with isocyanate groups and further at least one hydrophilic group acting as co-dispersant of the compound (A) in water either directly or after the reaction with a neutralizing agent to provide a salt, (ix) at least one carboxylic acid hydrazide compound, (x) optionally, at least one compound containing at least one group capable of reacting with isocyanate groups but no ethylenically unsaturated groups, and the radiation curable aqueous composition (I) further comprises at least one external emulsifier (B) and optionally at least one co-solvent (D).

6. The radiation curable aqueous composition (I) of claim 1, further comprising at least one external emulsifier (B) and optionally at least one co-solvent (D).

7. The radiation curable aqueous composition of claim 1, wherein the compound containing free isocyanate groups (i) is an aliphatic and/or cycloaliphatic polyisocyanate.

8. The radiation curable aqueous composition of claim 1, wherein the carboxylic acid hydrazide compound (iv) is selected from hydrazides that have a solubility in demineralized water of at least 2 g/l and/or from hydrazides that have a solubility in basic water of at least 2 g/l.

9. The radiation curable aqueous composition of claim 1, wherein the carboxylic acid hydrazide compound (iv) is one or more selected from the group consisting of adipic acid dihydrazide, sebacic acid dihydrazide, icosanedioic acid dihydrazide, valine dihydrazide, and valeric hydrazide.

10. The radiation curable aqueous composition of claim 1, wherein the molar ratio of NH2 groups provided by the carboxylic acid hydrazide compound (iv) over the residual NCO groups obtained after reaction of the compounds (i) to (iii) and optionally (v) is more than 0.4.

11. The radiation curable aqueous composition of claim 1, wherein the amount of carboxylic acid hydrazide compound (iv) used for the synthesis of compounds the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2) or the saturated carboxylic acid hydrazide-containing compound (H1), expressed in % wt of active —NH—NH— groups relative to the total weight of compounds (H2), (H1), and (EC) is not higher than 2 wt %.

12. The radiation curable aqueous composition (I) of claim 1, further comprising at least one ethylenically unsaturated compound (C) different from the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2) and, where present, (EC) is an unsaturated compound (C) is selected from the group consisting of urethane (meth)acrylates, epoxy (meth)acrylates, polyester (meth)acrylates and/or (meth)acrylic (meth)acrylates, and self-water-dispersible polyurethane (meth)acrylate.

13. The radiation curable aqueous composition of claim 12, wherein the unsaturated compound (C) is prepared from the same building blocks as the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2) with the exception that the compound (C) does not contain any compound (iv) building blocks.

14. The radiation curable aqueous composition of claim 1 further comprising at least one of the following compounds: 4) at least one photo-initiator, 5) at least one additive that is selected from the group consisting of UV stabilizers and UV absorbers, 6) at least one hydrazine and/or at least one hydrazide compound different from the ethylenically unsaturated carboxylic acid hydrazide-containing compound (H2).

15. A coating composition, paint, ink, varnish or adhesive prepared from a radiation curable aqueous composition according to claim 1.

16. A process for preparing a coating with a reduced photo-yellowing, said process comprising the steps of: (a) providing a radiation curable aqueous composition (I) according to claim 1, (b) applying said composition onto a surface to form a dry layer that is from 2 to 200 μm thick, and (c) irradiating the surface with actinic radiation.

17. The coating obtained via the process according to claim 16, wherein the photo-yellowing value is below 2, this photo-yellowing value being defined as the difference between the ‘b’ value according to CIEALAB scale measured 20 minutes before cure and the ‘b’ value measured 10 minutes after cure for a 25 μm thick dry layer cured with a Hg lamp with an energy of 1,100 mJ/cm2.

18. A method of reducing photo-yellowing comprising providing the radiation curable aqueous composition (I) of claim 1 with a radiation curable ethylenically unsaturated compound (C) not containing any compounds (iv) in its backbone, wherein photo-yellowing of the radiation curable ethylenically unsaturated compound (C) not containing any compounds (iv) in its backbone is reduced.

Description

EXAMPLES

Preparation Example 1

(1) A double-wall glass reactor equipped with a mechanical stirrer, a thermocouple, a vapor condenser and a dropping funnel was charged at 40° C. under air-sparging with 409.5.0 g of Isophorone diisocyanate (IPDI), 1.30 g Butylated hydroxytoluene (BHT), 340 g of acetone, 1023.6 g of polyadipate of neopentylglycol (IOH 58) and 97.16 g dimethylolpropionic acid (DMPA). The reaction mixture was completely homogenized and 1.00 g of Bismuth decanoate is added. The mixture was heated to 60° C. and reacted under reflux for 4 hours. A NCO titer of 0.66 meq/g is obtained. The temperature was decreased to 50° C. and 693.0 g of a mixture of dipentaerythritol penta & hexa acrylate (DPHA) with an IOH of 59.6 was added to the mixture. The temperature was increased to 75° C. and the mixture was maturated 6 hours. The prepolymer obtained had a viscosity of 4.5 Pa.Math.s at 60° C., a solids content of 85.2% and a residual NCO content of 0.161 meq./g (value measured the day after synthesis).

Preparation Example 2

(2) A double-wall glass reactor equipped with a mechanical stirrer, a thermocouple, a vapor condenser and a dropping funnel was charged at 40° C. under air-sparging with 341.6 g of Isophorone diisocyanate (IPDI), 0.90 g Butylated hydroxytoluene (BHT), 202 g of acetone, 753.5 g of polyadipate of neopentylglycol (IOH 58) and 79.54 g dimethylolpropionic acid (DMPA). The reaction mixture was completely homogenized and 0.90 g of Bismuth decanoate is added. The mixture was heated to 60° C. and reacted under reflux for 4 hours. A NCO titer of 0.84 meq/g was obtained. The temperature was decreased to 50° C. and 641.3 g of a mixture of dipentaerythritol penta & hexa acrylate with a IOH of 59.6 is added to the mixture. The temperature was increased to 75° C. and the mixture was maturated 6 hours. The prepolymer was further diluted with 40 g acetone. The prepolymer obtained has a viscosity of 6.6 Pa.Math.s at 60° C., a solids content of 90.1% and a residual NCO content of 0.228 meq./g (value measured the day after synthesis).

Example 1

(3) 212 g of a water solution of 3.98 g of sodium hydroxide was added in 10 minutes to 501.4 g of the prepolymer of Preparation Example 1 pre-heated at 60° C. Phase inversion was obtained by further addition of 386 g of demineralized water followed immediately by the addition of solution of 5.62 g of Adipic acid dihydrazide in 65 g of water. 0.5 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained. Further 30 g of water are added in order to obtain a solids content near 40%.

(4) Equivalent ratio between NH2 and residual NCO was 0.8 in this example.

Example 2

(5) 212 g of a water solution of 3.98 g of sodium hydroxide and 7.73 g of adipic acid dihydrazide was added in 10 minutes to 501.4 g of the prepolymer of preparation example 1 pre-heated at 60° C. Phase inversion was obtained by further addition of 449 g of demineralized water. 0.5 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained. Further 30 g of water were added in order to obtain 40% solids.

(6) Equivalent ratio between NH2 and residual NCO was 1.1 in this example.

Example 3

(7) Same recipe as in Example 2, but with the adipic acid di-hydrazide quantity increased to 9.62 g.

(8) Equivalent ratio between NH2 and residual NCO was 1.3 in this example.

Comparative Example 4-R

(9) Same recipe as in Example 1, but here adipic acid di-hydrazide was replaced by 2.40 g of propylenediamine.

(10) Equivalent ratio between NH2 and residual NCO was 0.8 in this example.

Comparative Example 5-R

(11) 10.53 g of triethylamine was added to 505 g of the prepolymer of Preparation Example 1 pre-heated at 60° C. and homogenized for 15 minutes. Phase inversion was obtained by addition of 682 g of demineralized water added in 20 minutes. 0.5 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained.

(12) No amine or hydrazide was added in this example.

Comparative Example 6-R

(13) As further counter example the radiation curable aqueous composition of Example 2 of the patent WO2012-013488 A1. Again, this was an UV PUD not made according to the invention.

Example 7

(14) 324 g of a water solution of 5.77 g of sodium hydroxide and 14.89 g of adipic acid dihydrazide was added in 10 minutes to 700 g of the prepolymer of Preparation Example 2 pre-heated at 60° C. Phase inversion was obtained by further addition of 621 g of demineralized water. 0.7 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained.

(15) Equivalent ratio between NH2 and residual NCO was 1.07 in this example.

Example 8

(16) Made with the same recipe as example 7 but with the adipic acid dihydrazide replaced by 16.59 g of Isophtalic acid dihydrazide.

(17) Equivalent ratio between NH2 and residual NCO was 1.07 in this example.

Comparative Example 9-R

(18) Made with the same recipe as example 7, but with the adipic acid dihydrazide replaced by 7.70 g of carbo dihydrazide (from Sigma-Aldrich).

(19) Equivalent ratio between NH2 and residual NCO was 1.07 in this example.

Comparative Example 10-R

(20) Made with the same recipe as example 7, but here the adipic acid dihydrazide was replaced by 18.2 g of 15% solution in water of hydrazine.

(21) Equivalent ratio between NH2 and residual NCO was 1.07 in this example.

(22) Results obtained with the above Examples and Comparative Examples are summarized in Tables 1-4 below. Amounts are in grams unless specified otherwise.

(23) TABLE-US-00001 TABLE 1 Main characteristic of the examples and comparative examples—First series Ex1 Ex2 Ex3 Ex4-R Ex5-R Ex6-R Hydrazide ADH ADH ADH PDA none none or amine NH2/NCO 0.8 1.1 1.3 0.8 — — % NHNH 0.45 0.61 0.76 0 0 0 groups * Viscosity at 112 101 53 315 427 303 25° C. (mPa .Math. s) % solids 39.5 40.6 39.9 40.0 38.9 41.2 pH 7.27 7.16 7.35 7.41 7.53 7.40 Particle size 77 75 65 80 69 98 (nm) * relative to the total weight of compounds (A), prior to dispersion, emulsion or solution

(24) TABLE-US-00002 TABLE 2 Photo yellowing (Δb = b before cure − b just after cure)—First series Δb at various thickeness Ex1 Ex2 Ex3 Ex4-R Ex5-R Ex6- R 0.63 +− 0.20 mil 1.43 1.25 1.01 1.85 2.02 2.67 1.13 +− 0.36 mil 1.53 1.30 1.01 2.05 2.30 3.27

(25) The above Table shows that UV PUD's according to the invention that were prepared from carboxylic acid hydrazides (compounds iv) have a much lower yellowing after cure. The higher the concentration of hydrazide, the lower the photo-yellowing. When the hydrazide was replaced by a diamine (Comparative Example 4-R), there was no such effect.

(26) A second series of Examples and Comparative Examples was prepared. Results are summarized in Tables 3 and 4 below:

(27) TABLE-US-00003 TABLE 3 Main characteristic of the Examples and the Comparative Examples - Second series Ex7 Ex8 Ex9-R Ex10-R Amine/Hydrazide ADH IDH CDH N.sub.2H.sub.4 NH2/NCO 1.07 1.07 1.07 1.07 % NHNH groups 0.79 0.79 0.79 0.80 Viscosity at 25° C. 37 70 47 44 (mPa .Math. s) % solids 39.8 40.5 39.6 39.8 pH 7.29 7.50 7.45 7.38 Particle size (nm) 65 54 55 68

(28) TABLE-US-00004 TABLE 4 Photo yellowing (Δb = b before cure − b just after cure) - Second series Δb at 1 mil thickness Ex7 Ex8 Ex9-R Ex10-R 1.13 +− 0.36 mil 1.5 2.5 3.9 2.7

(29) The above Table shows that the incorporation of a carbohydrazide (Example 9-R) did not have the desired effect whereas the incorporation of a carboxy acid hydrazide (a compound (iv) according to the claims) significantly reduced photo-yellowing. Also hydrazine (Example 8-R) proved less suitable on general.

Comparative Examples 11-R and Example 12

Preparation Example 3 (for Examples 11-R and 12)

(30) A pressurized reactor equipped with a mechanical stirrer and a thermocouple was charged with 56.6 g Cardura™ E10P (Hexion) and 24 g Methyl Ethyl Ketone (MEK). After inertization with nitrogen, reactor was heated to 160-165° C. A pressure of 2-2.5 bar was reached inside the reactor. In parallel a solution of monomers containing 218.86 g methyl methacrylate, 64.16 g Butyl acrylate and 37.74 g acrylic acid and a solution of initiator with 5.7 g Di-t-Butyl peroxid and 20 g MEK are prepared. Both mixtures are fed into the reactor in parallel within 5-6 h. At the end of the addition, the monomers and initiators pipes were rinsed with 10 g MEK. Polymer mixture was then matured 2 h, cooled down to 90° C. and diluted with 156 g MEK.

(31) The prepolymer thus prepared had the following characteristics. Measuring methods are given between brackets. Hydroxyl value IOH: 47 mg KOH/g (DIN EN ISO 4629) Acid value AN: 44.1 mg KOH/g (DIN EN ISO 2114) Viscosity: 870 mPas (DIN EN ISO 3219, 25 1/s; 23° C.) Mw: 8 400 g/mol (measured via GPC as mentioned infra) Non-volatile matter: 64.4 wt % (solids content)—(DIN EN ISO 3251, 1 h drying of a 2 g sample in an oven at 125° C.)

Comparative Example 11-R—No Compound (iv)

(32) A double-wall glass reactor equipped with a mechanical stirrer, a thermocouple, a vapor condenser and a dropping funnel was charged at 40° C. under air-sparge with 543 g polymer 1 above, 0.58 g Butylated hydroxytoluene (BHT) and 116.6 g of a mixture of dipentaerythritol penta & hexa acrylate (DPHA) with a IOH of 59.6. When the reaction mixture was completely homogenized 0.56 g of Bismuth noedecanoate was added. After 10 minutes 27.7 g isophoronediisocynate (IPDI) was charged into the reactor. The mixture was heated to 80° C. and reacted under reflux for 6-8 hours. The prepolymer obtained had a residual NCO of 0.005 meq NCO/g.

(33) 28.1 g of sodium hydroxide solution at 30% was added in 10 minutes to the prepolymer of preparation example 3 pre-heated at 65° C. Phase inversion was obtained by further addition of 834 g of demineralized water. MEK was stripped under vacuum at a T° of 65-70° C. until a residual of MEK content below 0.05 wt % was obtained. Dispersion obtained was translucent, had a viscosity of 18 mPas, a solid content of 39.8 wt % and particle size of 56 nm.

Example 12

(34) A double-wall glass reactor equipped with a mechanical stirrer, a thermocouple, a vapor condenser and a dropping funnel was charged at 40° C. under air-sparge with 543 g polymer 1, 0.58 g Butylated hydroxytoluene (BHT) and 116.6 g of a mixture of dipentaerythritol penta & hexa acrylate with a IOH of 59.6. When the reaction mixture was completely homogenized 0.56 g of Bismuth noedecanoate was added. After 10 minutes 27.7 g isophoronediisocynate (IPDI) was charged into the reactor. The mixture was heated to 80° C. and reacted under reflux for 6-8 hours. The prepolymer obtained has a residual NCO content of 0.019 meq NCO/g.

(35) 144.6 g of a water solution of 8.4 g of sodium hydroxide and 13.9 g of adipic acid dihydrazide (ADH) was added in 10 minutes to the prepolymer of Preparation Example 3 pre-heated at 65° C. Phase inversion was obtained by further addition of 688.4 g of demineralized water. MEK was stripped under vacuum at a T° of 65-70° C. until a residual of MEK content below 0.05 wt % was obtained. Dispersion obtained was translucent, had a viscosity of 16 mPas, a solid content of 40.2 wt % and particle size of 61 nm.

(36) TABLE-US-00005 TABLE 5 Main QC characteristic of the examples and comparative examples - acrylated acrylic (A-2) Ex 11-R Ex 12 Hydrazide none ADH % NH—NH groups 0 1.33 Viscosity at 25° C. 18 16 (mPa .Math. s) % solids 39.8 40.2 pH 8.0 8.0 Particle size (nm) 56 61

(37) TABLE-US-00006 TABLE 6 Photo yellowing (b before cure − b just after cure) - Acrylated acrylic (A-2) Δb at 1 mil thickness Ex11-R Ex 12 2.4 1.9

(38) The above Table shows that incorporation of ADH (adipic acid hydrazide, a compound (iv) according to the claims) also decrease the photo-yellowing of water-based (meth)acrylated (meth) acrylics.

Examples 13-15 and Comparative Examples 16-R-17-R

Preparation Example 4

(39) A double-wall glass reactor equipped with a mechanical stirrer, a thermocouple, a vapor condenser and a dropping funnel was charged at 40° C. under air-sparging with 613.1 g of Isophorone diisocyanate (IPDI), 1.60 g Butylated hydroxytoluene (BHT), 355 g of acetone, 954.3 g of polyadipate of neopentylglycol (IOH 58) and 139.44 g dimethylolpropionic acid (DMPA). The reaction mixture was completely homogenized and 0.90 g of Bismuth decanoate was added. The mixture was heated to 60° C. and reacted under reflux for 4 hours. A NCO titer of 0.95 meq./g was obtained. The temperature was decreased to 50° C. and 1484.4 g of a mixture of dipentaerythritol penta & hexa acrylate with a global IOH of 59.6 was added to the mixture. The temperature was increased to 75° C. and the mixture was maturated 6 hours. The prepolymer was further diluted with 40 g acetone. The prepolymer obtained had a viscosity of 5.6 Pa.Math.s at 60° C., a solids content of 89.8% and a residual content of 0.242 meq. NCO/g (value measured the day after synthesis).

Example 13

(40) 324 g of a water solution of 6.10 g of sodium hydroxide and 15.57 g of Adipic acid dihydrazide was added in 10 minutes to 700 g of the prepolymer of preparation example 4 pre-heated at 60° C. Phase inversion was obtained by further addition of 575 g of demineralized water. 0.44 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained.

(41) Equivalent ratio between NH2 and residual NCO was 1.14 in this example.

Example 14

(42) 320 g of a water solution of 6.10 g of sodium hydroxide and 8.91 g of Adipic acid dihydrazide was added in 10 minutes to 700 g of the prepolymer of preparation example 4 pre-heated at 60° C. Phase inversion was obtained by further addition of 575 g of demineralized water. 0.44 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained.

(43) Equivalent ratio between NH2 and residual NCO was 0.65 in this example.

Example 15

(44) 315 g of a water solution of 6.10 g of sodium hydroxide and 5.88 g of Adipic acid dihydrazide was added in 10 minutes to 700 g of the prepolymer of preparation example 4 pre-heated at 60° C. Phase inversion was obtained by further addition of 575 g of demineralized water. 0.44 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained.

(45) Equivalent ratio between NH2 and residual NCO was 0.43 in this example.

Example 16-R (Variable Results)

(46) 312 g of a water solution of 6.10 g of sodium hydroxide and 2.84 g of Adipic acid dihydrazide was added in 10 minutes to 700 g of the prepolymer of preparation example 4 pre-heated at 60° C. Phase inversion was obtained by further addition of 575 g of demineralized water. 0.44 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained.

(47) Equivalent ratio between NH2 and residual NCO was 0.17 in this example

Comparative Example 17-R

(48) 308 g of a water solution of 6.10 g of sodium hydroxide was added in 10 minutes to 700 g of the prepolymer of preparation example 4 pre-heated at 60° C. Phase inversion was obtained by further addition of 575 g of demineralized water. 0.44 g of BYK093 antifoaming agent was added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained.

(49) No amine or hydrazide was added in this example

(50) Results are summarized in Tables 7 and 8 below:

(51) TABLE-US-00007 TABLE 7 Main characteristic of the Examples and the Comparative Examples - Fourth series Ex13 Ex14 Ex15 Ex16 Ex17-R Hydrazide 2.6% 1.5% 1.0% 0.48% none NH2/NCO 1.14 0.65 0.43 0.21 0 % NHNH groups 0.90 0.52 0.34 0.17 0 Viscosity at 25° C. 33 56 67 98 99 (mPa .Math. s) % solids 39.3 39.8 39.7 39.4 40.2 pH 7.40 7.55 7.35 7.21 7.20 Particle size (nm) 56 62 58 60 48

(52) TABLE-US-00008 TABLE 8 Photo yellowing (Δb = b before cure − b just after cure) - Fourth series Δb at 1 mil thickness Ex13 Ex14 Ex15 Ex16 Ex17-R 1.55 1.8 1.9 2.05 2.1

(53) The above shows that overall the compounds (iv) are preferentially used in an amount such that the —NH—NH— content is at least 0.2 wt %, relative to the total weight of compounds (A). Below this amount a ‘delta’ b below 2 was more difficult to obtain.

(54) Pencil Hardness (Leneta and Glass)

(55) Scratch resistance (steel wool on Leneta): the testis performed by scratching the coating with the steel wool for 5 double rubs. The results are rated visually and recorded in a 1-5 scale: 5=no scratch; 4=very light scratch; 3=moderate scratch; 2=strong scratch; 1=very strong scratch. A high value (5) is expected to provide the best protection against any deterioration of the coated object.

(56) Stain resistance (Mustard) was measured on Leneta paper by applying 50 p of wet coating, drying and curing it. Mustard is put on the cured coating and protected with a watch glass. After a contact time of 1 hour the stain is wiped away, first dry and then with water and detergent. Visual evaluation of the coating surface is done, delta b* of the stain is measured and reported on a scale from 0 to 5 as follows: 5=No visible change; 4=Very slight change in color or gloss; 3=Slight change in color and/or gloss but the surface structure is not damaged; 2=Strong change in color and/or gloss but the surface structure is not damaged; 1=Strong marks and surface structure is damaged; 0=Surface structure completely damaged.

(57) Gloss measurements: Throughout the invention and also here gloss measurements were done with a BYK Gardner micro TRI-gloss 20-60-85 gloss-meter in accordance with DIN EN ISO 2813.

(58) The pendulum hardness (Persoz) measures the time (in seconds) for a pendulum with a given weight and geometry to amortize its oscillation amplitude between 2 defined angles. It is measured on glass plate (120 μm wet coating), on 3 places of the coating surface and the mean value is calculated. Elevated values are indicative of hard coatings. It follows ASTM D4466.

(59) The water release was assessed by observing the visual aspect after 48 hours of non-pigmented coating made in the following conditions: 200 p wet layers were applied with a doctor blade on grey PVC 3 mm sheets. Water was evaporated from the coating during 6 minutes at 40° C. Subsequently coatings were exposed to UV radiations from a 80 Watt Hg lamp at a defined conveyer speed: 1×5 m/minute. Rating was on a scale from 5 to 0, wherein 5 stands for transparent coatings (very good water release properties) and 0 stands for white opaque coatings (very bad water release properties). According to the rating used 1 stands for very hazy/grey with white zones, 2 stands for very hazy/grey, 3 stands for hazy/grey, 4 stands for light hazy/light grey and 5 stands for transparent.

(60) “Anfeuerung” covers the wetting of wood and the enhancement of the wooden structure. The test is performed by applying a coating on wood (sappelli), drying it and curing it by UV. A visual inspection is used to evaluate the warm wet look aspect, compared to a reference. Sappelli is chosen as it is a dark wood and appropriate to evidence whitening coming from a waterborne system. Rating is from “1” (best) to “5” (worst).

(61) Adhesion (cross hatch tape): The adhesion on wood is assessed using the cross-cut test according to ISO 2409. 5 cuts of ˜1 cm long and spaced by ˜1 mm are made in the coating using a knife, followed by 5 similar cuts in the transversal direction. The adhesion was measured using an adhesive tape (Scotch®) firmly pressed on the cross-cut coating and removed rapidly; the damage to the cross-cut surface area of the coating due to adhesion loss is expressed in a 0-5 scale, 5=best.

(62) TABLE-US-00009 TABLE 9 Coating formulation Sample C D Manufacturer Example 3 97.0% Allnex Comparative example 6-R 97.0% Allnex Additol VXW 6360 (1:1 w/water) 1.0% 1.0% Allnex Irgacure 500 1.5% 1.5% Ciba

(63) TABLE-US-00010 TABLE 10 Coating evaluation Ex 3 Ex 6-R Pencil Hardness Leneta <6B <6B Pencil Hardness Glass 3H 3H Steel Wool Scratch (DR) Leneta 1 1 Stain Test - Mustard (0-3) Leneta 3 3 Stain Test - Mustard (b*) Leneta 27 21 Gloss - 20° (glu) Leneta 68 70 Gloss - 60° (glu) Leneta 88 92 Gloss - 85° (glu) Leneta 98 98 Persoz Hardness (s) Leneta 241 286 Water Release Grey PVC 3 5 Anfeuerung Wood slightly good wet look contrast Cross Hatch Adhesion (0-5) Wood 5 5

(64) The above shows that radiation curable compositions (I) of the invention do not deteriorate desired properties of a coating.

Preparation Example 4

(65) A first double-wall glass reactor equipped with a mechanical stirrer, a thermocouple, a vapor condenser and a dropping funnel was charged at 40° C. with 180.96 g of 1,1′-methylene bis[4-isocyanatocyclohexane] (H12MD1), 188 g of acetone, 26.50 g dimethylolpropionic acid (DMPA), 0.99 g of trimethylolpropane (TMP), 222.22 g of polyadipate of neopentylglycol (I.sub.OH 58) and 6.90 g of ethyleneglycol (EG). The reaction mixture was completely homogenized and 0.15 g of Bismuth neodecanoate is added. The mixture was heated to 60° C. and reacted under reflux for 9 hours. A NCO titer of 0.72 meq./g was obtained. The prepolymer was further diluted with 30 g acetone and neutralized with 19.97 g of triethylamine. The prepolymer obtained had a solid content closed to 70%.

(66) 39.2 g of adipic dihydrazide (ADH) was dissolved in 715 g of water in a second reactor equipped in a same way as the first one. The content of the first reactor was added in the second one, in 20 minutes and let homogenize 30 minutes more. 0.35 g of BYK093 antifoaming agent was then added to the dispersion and acetone was stripped under vacuum at a T° of 50-55° C. until a residual of acetone content below 0.05% was obtained. Further 30 g of water were added in order to obtain a solid content of 38.87%. Dispersion obtained was a non-radiation curable PUD containing 2.83% —NH—NH— (expressed in solids weight).

(67) This PU dispersion had a viscosity of 635 mPa.Math.s, pH of 8.04 and particle size of 47 nm

Comparative Example 18R

(68) Ucecoat 7849, commercial UV PUD not made according to the present disclosure.

(69) Main characteristics 34.8% NV, 49 mPa.Math.s, particle size 72 nm

Example 19

(70) 100 p of Ucecoat 7849 was physically blended with 38.4 p of the PUD of preparation example 4 giving a solids ratio of 70% Uc7849/30% prepa ex 4 and 0.85% NHNH groups (expressed on the total solids of the blend)

Example 20

(71) 100 p of Ucecoat 7849 was physically blended with 89.5 p of the PUD of preparation example 4 giving a solids ratio of 50% Uc7849/50% prepa ex 4 and 1.42% NHNH groups (expressed on the total solids of the blend)

Preparation Example 5

(72) A first double-wall glass reactor equipped with a mechanical stirrer, a thermocouple, a vapor condenser and a dropping funnel was charged at 40° C. with 180.96 g of Isophorone diisocyanate (IPDI), 234.08 g of Polycaprolactone diol Mw550 (I.sub.OH 203) and 0.09 g of triphenylphosphite. The reaction mixture was completely homogenized and 0.02 g of dibutyltinlaurate (DBTL) is added. The mixture was heated progressively in 30 min to 90° C. and reacted for 1 hour. A NCO titer of 1.93 meq./g was obtained. A blend of 204.8 g tripropyleneglycoldiacrylate (TPGDA), 106.9 g of Hydroxyethylacrylate (HEA), 0.03 g of hydroquinone and 0.33 g of dibutyltinlaurate (DBTL) was fed in 2 hours to the reactor and the mass temperature maintained between 85 and 95° C. After 30 min, the temperature was decreased to 60° C. The NCO titer obtained at this stage was 0.26 meq./g. 26.44 g of sebacic acid dihydrazide was added to the reactor in 10 minutes. 20 min after the feeding, a NCO titer of 0.02 meq./g was obtained. The final product had a viscosity of 3160 mPa.Math.s at 60° C. This sample contained 0.86% NHNH groups by weight.

Preparation Example 6

(73) A first double-wall glass reactor equipped with a mechanical stirrer, a thermocouple, a vapor condenser and a dropping funnel was charged at 40° C. with 180.96 g of Isophorone diisocyanate (IPDI), 291.82 g of Polycaprolactone diol Mw550 (I.sub.OH 203) and 0.09 g of triphenylphosphite. The reaction mixture was completely homogenized and 0.02 g of dibutyltinlaurate (DBTL) was added. The mixture was heated progressively in 30 min to 90° C. and reacted for 1 hour. A NCO titer of 1.93 meq./g was obtained. A blend of 204.8 g tripropyleneglycoldiacrylate (TPGDA), 1116.39 g of Hydroxyethylacrylate (HEA), 0.03 g of hydroquinone and 0.33 g of dibutyltinlaurate (DBTL) was fed in 2 hours to the reactor and the mass temperature was maintained between 85 and 95° C. Two hour after the feeding, a NCO titer of 0.10 meq./g was obtained. The final product had a viscosity of 660 mPa.Math.s at 60° C.

Example 21

(74) A double-wall stainless steel vessel connected with a heated bath at 60′C was charged with 51.9 g of urethane acrylate of preparation example 5, 5.2 g of MAXEMUL 7101 and 3.9 g of DOWANOL DPM. The blend was stirred at a rotation speed of 100 rpm with a cowless propeller having a diameter of 60 mm until the temperature reached 60′C. The mixture was then stirred at a rotation speed of 2000 rpm while 16 g of water at room temperature was added at a constant flow rate during about 5 minutes using a peristaltic pump to reach a solid content of ca. 74%. A phase inversion point corresponding to a maximum of the viscosity was observed and the mixture was further sheared at a rotation speed of 2000 rpm for an additional period of 20 min at a constant temperature of 60′C. An additional quantity of 23 g of water was then added to the mixture at a constant flow rate during about 5 minutes, while the cowless rotation speed was progressively decreased to 200 rpm and the temperature decreased to room temperature. The final emulsion had a solid content of ca. 57%, particle size in the range of 700 nm and it was stable at least 3 days at room temperature.

Comparative Example 22R

(75) This comparative example was prepared like the example 21 but preparation example 6 was used in place of preparation example 5. The final emulsion had a solid content of ca. 57%, particle size in the range of 700 nm and it was stable at least 3 days at room temperature.

(76) This comparative example did not contain any NHNH groups.

(77) TABLE-US-00011 TABLE 11 Improvement of the photo yellowing of an UV PUD by formulation with a non-radiation curable polyurethane dispersion containing hydrazide groups Ex 18-R Ex 19 Ex 20 Δb at 1 mil thickness 2.06 1.77 1.62 % of prepa ex 4 0 .sup. 30% .sup. 50% % NHNH groups on dry solids 0 0.85% 1.42%

(78) Decrease of photo-yellowing is obtained by formulation of a commercial UV PUD (UV PUD formulation not made according to this invention) with non-radiation curable polyurethane dispersion in which hydrazide as incorporated.

(79) TABLE-US-00012 TABLE 12 Improvement of the photo yellowing of urethane acrylate emulsions (curing made in two UV exposure conditions) Ex 21 Ex 22-R Δb at 1 mil thickness 1154 mJ/cm.sup.2 1.50 2.70 2645 mJ/cm.sup.2 1.58 2.20 % NHNH groups on dry solids 0.66% 0