New solutions to reduce yellowing directly after UV-cure to simplify color matching

Transcription

1 26 October 2017 New solutions to reduce yellowing directly after UV-cure to simplify color matching RadTech Europe 2017 Jean-Yves Salviato Joshua Hollett Elodie Siband

2 What is yellowing on cure? Benchmark of WB UV curable resins Potential causes of the yellowing on cure CONCLUSION & FOLLOW-UP additives (stabilizers, process additives ) resin composition 26 October

3 b 2 b 3 b 1 26 October

4 Photo-yellowing or yellowing on cure Yellowing on cure must be distinguished from long term yellowing It s a yellowing that occurs during the radiation curing of the resin and that generally decreases after few hours or days but generally not to the initial level Occurs in all Radiation curing systems (UV, EB or LED/HUV) Causes and main factors are different than the ones involved in long term yellowing Makes the online color matching very difficult It s a limiting factor for use of WB UV for white or low shade colors 26 October

5 Experimental data STD formulation and conditions of evaluation of the yellowing after cure are identical for all the products: Ingredient % Loading WBUV Resin 96.5 Irgacure Additol VXW 6360 (1:1 w/ water)* 2 Total substrate: Raypaul powder coated (white) Al panel - application: bar coater - film thickness: 1 mil (+- 0.1) or the thickness mentioned in the report - drying condition: 50 c - curing condition: 1,100 mj/cm2 (Hg lamp) - Color measurement with BYK colorguide Δb = b2 b1 wherein b1 is the b* measured 20 minutes before the cure with UV b2 is the b* measured 10 min after the UV cure 26 October

6 compet 1 compet 2 compet 3 allnex1 allnex2 compet 4 allnex 3 allnex 4 compet 5 allnex 5 allnex 6 compet 6 allnex 7 allnex 8 allnex 9 allnex 10 allnex 11 compet 7 allnex 12 allnex 13 allnex 14 compet 8 Mean Δb Benchmark: competitor >< our WB UV resins allnex resins competitors resins allnex starting point 26 October

7 compet 1 compet 2 compet 3 allnex1 allnex2 compet 4 allnex 3 allnex 4 compet 5 allnex 5 allnex 6 compet 6 allnex 7 allnex 8 allnex 9 allnex 10 allnex 11 compet 7 allnex 12 allnex 13 allnex 14 compet 8 Mean Δb We want to obtain allnex resins competitors resins allnex starting point 26 October

8 Potential causes of yellowing on cure Conditions of cure Photoinitiators Coating additives Yellowing on cure Water impact Process additives UV polymer composition 26 October

9 2 potential improvement routes Stabilizers sterically hindered phenols Catalysts metal, organo-metal In-can preservatives PU backbone composition Residual NCO before dispersion possibility for modification DOE NCO capping in water 26 October

10 Impact of additives potential route of improvement 1 Principle of the DOE - 10x standard level of additives are added to an industrial UV PUD prepolymer - Full factorial + 2 extra points and trials with PP dispersed in water Run pattern Based on stab 1 stab 2 stab 3 stab 4 cata1 cata2 modif stab biocide 1 PP PP PP PP PP PP PP PP PP PP PP PP PP PP PP PP PP PP UV PUD UV PUD UV PUD October

11 Main effects of additives Addition of 10x cata 2 increase a lot the yellowing after cure - artifact linked to polymer degradation (2x cata content has no effect) Very low impact of the other components 26 October

12 Stabilizers impact (cata 2 post-addition omitted): Stabilizers have generally a positive but too limited impact on the yellowing before This high level of addition cannot be applied for many reasons (labeling, migration, yellowing after neutralization) Limiting it to 1000ppm of each has no significant impact on the yellowing on cure No impact of in-can preservatives 26 October

13 Resin composition - potential route of improvement 2 Starting point: lean UV PUD composition - polyadipate ester diol - DMPA neutralized with NaOH - Isocyanate - Capping agent: mono OH polyacrylate oligomer Capping of the excess of NCO with propanediamine (PDA) H 2 N NH 2 hydrazine H 2 NNH 2 carboxylic acid dihydrazide H 2 N N H R N H N H 2 O O carbohydrazide NH 2 NHNH NH 2 O 26 October

14 First results: positive impact of the ADH ADH low ADH medium ADH high PDA no capping Ref %NHNH groups Viscosity at 25 C (mpa.s) % solids ph Particle size (nm) Δb at various thicknesses 0.63 mil 1.13 mil 3,5 3,27 3 2,67 H 2 N NH O ADH O NH NH 2 2,5 2 1,5 1 1,43 1,53 1,25 1,3 1,01 1,01 1,85 2,05 2,02 2,3 0,5 0 ADH low ADH medium ADH high PDA no ext Ref 26 October

15 Hydrazine & different grades of Hydrazide Viscosity at 25 C (mpa.s) Adipic acid dihydrazide Isophtalic acid dihydrazide Carbo dihydrazide Hydrazine ADH IDH CDH N2H % solids Same thickness and -NH-NH- concentration ph Particle size (nm) Δb at 1.1 ± 0.3 mill 4,5 4 3,5 3 2,5 2 1,5 1 0,5 0 3,9 2,5 2,7 1,5 ADH IDH CDH N2H4 26 October

16 Same modification applied on WB acrylated acrylic WB acrylated acrylics obtained following our patent WO use isocyanate as coupling agent in order to functionalize the acrylic backbone with radiation curable double bonds. This isocyanate can also be used to incorporate hydrazide functionalities Hydrazide ADH none %NH-NH groups Viscosity at 25 C (mpa.s) % solids ph Particle size (nm) ,5 2 1,5 1 0,5 0 Δb at 1.1 ± 0,3 mill 1,9 ADH 2,4 none Same trends is observed 26 October

17 UV PUD 1 UV PUD 2 UV PUD 3 Acryl Acrylic compet 1 compet 2 compet 3 allnex1 allnex2 compet 4 allnex 3 allnex 4 compet 5 allnex 5 allnex 6 compet 6 allnex 7 allnex 8 allnex 9 allnex 10 allnex 11 compet 7 allnex 12 allnex 13 allnex 14 compet 8 Mean Δb Comparison with the benchmark allnex resins competitors resins allnex starting point Hydrazide modified resins 26 October

18 NH Conclusions Best reduction of yellowing on cure is obtained by the reaction of aliphatic carboxylic hydrazide with aliphatic polyisocyanates which gives the following active group How is it working? Hypotheses - Reducing effect of the hydrazide 26 October

19 NH Conclusions Best reduction of photo-yellowing is obtained by the reaction of aliphatic carboxylic hydrazide with aliphatic polyisocyanates which gives the following active group How is it working? Hypotheses - Reducing effect of the hydrazide - Electron delocalization - Metal complexation 26 October

20 Properties of coating made with modified UV PUD Formulations: 97p UV-PUD (40% solids) 1p Additol VXW6360 (1/1 in water) 1,5p Irgacure 500 Substrate Hydrazide modif allnex 7 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 Gloss - 20 (glu) Leneta Gloss - 60 (glu) Leneta Gloss - 85 (glu) Leneta Persoz Hardness (s) Leneta Water Release Grey PVC 3 5 Anfeuerung Wood slightly wet look good contrast Cross Hatch Adhesion (0-5) Wood October

21 Next steps ongoing developments These results open new opportunities for WB UV in order to be the technology of choice for more applications/markets : Product - Other water-based UV resin (emulsions, water soluble/dilutable) - 100% radiation cure resin Curing conditions - Electron beam - Low energy curing (LED, HUV) Applications - Primers, topcoat - Ink, graphic applications, inkjet - Outdoor coatings Substrates - Wood, plastic, cement - Paper, coated substrates (printed materials, melamine coated ) 26 October

22 disclaimer Notice: Trademarks indicated with the, or * are registered, unregistered or pending trademarks of Allnex IP s.à.r.l. or its directly or indirectly affiliated Allnex Group companies. Disclaimer: Allnex Group companies ( Allnex ) decline any liability with respect to the use made by anyone of the information contained herein. The information contained herein represents Allnex's best knowledge thereon without constituting any express or implied guarantee or warranty of any kind (including, but not limited to, regarding the accuracy, the completeness or relevance of the data set out herein). Nothing contained herein shall be construed as conferring any license or right under any patent or other intellectual property rights of Allnex or of any third party. The information relating to the products is given for information purposes only. No guarantee or warranty is provided that the product and/or information is adapted for any specific use, performance or result and that product and/or information do not infringe any Allnex and/or third party intellectual property rights. The user should perform his/her own tests to determine the suitability for a particular purpose. The final choice of use of a product and/or information as well as the investigation of any possible violation of intellectual property rights of Allnex and/or third parties remains the sole responsibility of the user Allnex Belgium SA. All Rights Reserved 26 October