Caprolactone chemistry Tailor-made polymerization by: Ring-opening polymerization Initiator H-functionality to react with f.x. NC or melamine crosslinkers General properties Very low acid number (<1 mg KH/g) Exactly defined functionality Narrow molecular weight distribution Low viscosity generate low VC Due to very controlled ring-opening polymerization
Polycaprolactones General structures Perstorp has produced caprolactone monomer for 40 years biggest producer of caprolactones in the world Supply caprolactone polyols for a wide range of applications Coatings PUDs PU elastomers PU adhesives Grades for crosslinked coatings Functionality 2-4 Mw 300-2000 g/mol H-content 4.1-17% { } CH 2 CH 2 CH 2 H n { } n { } n H Trifunctional polycaprolactone H H (H 2 C) 5 (H 2 C) 5 Difunctional polycaprolactone H n n (CH 2 ) 5 H n (CH 2 ) 5 H Tetrafunctional polycaprolactone n
Capa Polyols - ur offer Caprolactones are aliphatic, liquid, low viscosity polyols suitable as reactive diluents with: Very low acid number (<1 mg KH/g) Standard grades - workhorses Product Type Mw H-value (mg KH/g) Exactly defined functionality H % Viscosity (mpas @23 C) Recommendations Capa 2054 Diol 550 204 6.2 340 1K HMMM SB Capa 2085 Diol 830 135 4.1 330 (@ 35 C) 1K HMMM SB Capa 3050 Triol 540 310 9.4 1,190 2K PUR WB & SB Capa 3091 Triol 900 183 5.5 1,246 2K PUR & 1K HMMM SB Capa 4101 Tetrol 1,000 218 6.6 1,850 2K PUR WB & SB Special grades - for high functionality / dense crosslinking Product Type Mw H-value (mg KH/g) H % Viscosity (mpas @23 C) Recommendations Capa 2043 Diol 400 280 8.5 240 2K PUR & 1K HMMM WB & SB Capa 3031 Triol 300 560 17 170 2K PUR WB & SB Special grades - for SB 2K PUR soft feel formulations Product Type Mw H-value (mg KH/g) H % Viscosity (mpas @60 C) Remarks Capa 7203 Diol 2,000 56 1.7 1100 Polycarbonate co-polymer Capa 8025D Diol 2,000 56 1.7 870 Polylactide co-polymer
Application studies Properties of hydroxylfunctional components Solid content Viscosity H-content Mw Functionality wt-% mpas @23 C % g/mol Acrylic polyol 75 5,400 4.5* n.a. n.a. Polyester polyol 78 6,000 5.4* n.a. n.a. Capa 3050 100 1,200 9.4 540 3.0 Capa 4101 100 1,900 6.6 1,000 4.0 Acrylic emulsion 40 600 3.5* n.a. n.a. * n solids
2K PUR Solventborne formulations Straight forward additions, if pigmented formulations, preferably in grinding part Principle of formulations *Used to set final viscosity @ 22 sec in DIN Cup 4 All acrylic Ref polyester Mod. A Mod. B Mod. C Mod. D PART A Capa 3050 Capa 3050 Capa 3050 Capa 4101 Acrylic polyol 79.11 71.43 71.43 71.43 61.50 71.43 Polyester polyol 7.68 Capa 3050 7.68 3.44 7 Capa 4101 4.9 Solvent mixture 17.96 17.96 17.96 22.2 28.57 20.74 Additive package 0.93 0.93 0.93 0.93 0.93 0.93 DBTL (1% in BuAc) 2 2 2 2 2 2 Total: 100 100 100 100 100 100 PART B Low viscosity HDI-trimer 30.11 30.84 35.7 30.84 30.84 30.84 Solvent mixture* 16.4 16.6 20.7 10.4 0 13.5 In Mod. A - Capa 3050 replace reference polyester on weight basis In Mod. B - Capa 3050 replace reference polyester to match H content In Mod. C Double amount of Capa 3050 in order to stress influence In Mod. D - Capa 4101 replace reference polyester to match H content
g/l Solventborne formulations VC 400 395 390 385 380 375 370 365 360 355 350 All acrylic VC at spray viscosity Ref Polyester Mod. A Mod. B Mod. C Mod. D VC reduced in formulation already considered to be High solid Even more pronounced when doubling amount of polycaprolactone (Mod. B Mod. C) Important to use low viscosity NC crosslinkers Due to relatively high H-number
Weight loss (mg) Solventborne formulation Abrasion resistance 35 30 25 20 15 10 5 0 All acrylic Ref Polyester Mod. A Mod. B Mod. C Mod. D Abrasion test on steel panels, 500g load, 1000 cycles A combination of high crosslink density, low Tg and semicrystalline caprolactone segments give the coating a rubbery, elastomeric character
cm*kg Solventborne formulation Impact resistance 100 90 80 70 60 50 40 30 20 10 0 All acrylic Impact resistance at -25 C Ref Polyester Aliphatic, low Tg properties of caprolactone segments improve impact resistance at low temperature Also has an impact of stone chip resistance and rain erosion resistance Mod. A Mod. B Mod. C Mod. D Indirect impact Direct impact Especially pronounced effect on indirect (reverse) impact
Solventborne formulation Scratch resistance All Acrylic Ref polyester Mod. A Mod. B Mod. C Mod. D Plastic / Plastic transition 10 g 10 g 10 g 10 g 10 g 10 g Plastic / Fracture transition 140 g 140 g 180 g 220 g 230 g 200 g Low Tg of caprolactone segments reduce brittleness and risk of creating permanent scratch. Semi-crystallinity introduced by caprolactones also reduces internal stress and increases viscoelastic properties which improve reflow properties. Principle of Taber Model 550 Rotation speed 0.5 rpm: the coating is scratched by the indenter with a progressive increased load. Traces left by the indenter are evaluated on the film: Smooth scratch: Plastic deformation of the film which recovers by a slow reflow at temperature higher than Tg Permanent scratch: Fracture deformation of the film which remains even after slow reflow at T > Tg Measured: Critical load for plastic/fracture transition
Relative gloss decrease, % Solventborne formulation Accelerated weathering 120 Accelerated wheathering (QUV-B) gloss 20 100 80 60 40 20 0 0 500 1000 1500 2000 hours All acrylic Ref Polyester Mod. A Mod. B Mod. C Mod. D Excellent stability due to aliphatic structure with low acid number Even more pronounced with an increaced amount of polycaprolactones
Force in N Solventborne formulation Flexibility40 Mod. D 30 All acrylic Mod. A 20 Mod. B Ref Polyester 10 Mod. C 50 100 150 Strain in% Effect on strain is emphasized by result from double amount Possible to find a balance between strength and elongation
Waterborne formulations Polycaprolactones are essentially hydrophobic Not possible to dissolve in water Low molecular weight polycaprolactones are still suitable to add in systems based on acrylic emulsions due to: Low viscosity Relatively high H-number Excellent compatibility with acrylic polymer Migrate into hydrophobic emulsion droplets - Utilizing shear force - Utilizing existing emulsifiers Case sensitive
Waterborne formulation Emulsification Frequenny Mixing with an dissolver Effect of additions of 3-functional polycaprolactone (wt-%) on particle size distribution of an uncured acrylic emulsion 20 18 16 14 12 10 8 6 4 2 0 0,01 0,1 1 10 100 16% - stable peak Particle size [µm] 32% - peak is moving towards higher particles 40% - distinct bimodal particle size distribution instant separation Without Capa Add 8% Capa 3050 Add 13% Capa 3050 Add 16% Capa 3050 Add 32% Capa 3050 Add 40% Capa 3050
2K PUR Waterborne formulations 8% 8% Products All acrylic Capa 3050 Capa 4101 13% Capa 3050 13% Capa 4101 Acrylic emulsion 86.10 79.21 79.21 74.90 74.90 Capa 3050-6.89-11.19 - Capa 4101 - - 6.89-11.19 Defoamer 0.45 0.45 0.45 0.45 0.45 Wetting agent 0.45 0.45 0.45 0.45 0.45 Water (demin.) 13.00 13.00 13.00 13.00 13.00 100 100 100 100 100 Water dispersable NCcrosslinker 22.62 32.95 31.79 39.41 33.55 BGA 1.41 2.06 1.99 2.46 2.10 Water (demin.) * 5.02 21.04 18.51 27.02 23.25 Solid content 42.1 % 43.1 % 43.5 % 44.6 % 44.3 % VC 128.8 g/l 121.7 g/l 121.3 g/l 118.9 g/l 116.0 g/l NC/H = 1.2 *used to set viscosity at 25s DIN4
lvc (g/liter) Waterborne formulations Effect on VC 130 128 126 124 122 120 118 Capa 3050 Capa 4101 116 114 0 2 4 6 8 10 12 14 % Capa on total resins Replacement of acrylic polyol emulsion by polycaprolactones leads to a VC reduction of the formulation up to 10%.
Time (min) Waterborne formulations Influence on drying time 160 140 120 100 Drying time, T1 80 60 40 20 0 0% 8% 13% Level of addition (wt-%) Capa 3050 Capa 4101 Replacement of 8% of the acrylic polyol emulsion by 3-functional polycaprolactone has limited influence on the drying time of the coating
Waterborne formulations Gloss & Haze Gloss @ 20 Haze 96 94 92 90 88 86 84 82 0% 8% 13% 80 70 60 50 40 30 20 10 0 0% 8% 13% Capa 3050 Capa 4101 Level of addition (wt-%) Level of addition (wt-%) Significant improvement of gloss and haze are combination of: Perfect compatibility Low viscosity improve flow and levelling (longer open time) improve film formation polycaprolactones act as REACTIVE CALESCING AGENT
Inch*Ibs Waterborne formulations Impact resistance Reverse impact resistance (ASTM) 90 80 70 60 50 40 30 20 10 0 0% 8% 13% Level of addition (wt-%) Capa 3050 Capa 4101 Addition of polycaprolactones tremendously improves the impact resistance of the coating Due to semicrystalline and low Tg segments Even more pronounced in a WB formulation
Weight force (g) Waterborne formulations Scratch resistance 160 140 120 100 Scratch Plastic / fracture transition 80 60 40 20 0 0% 8% 13% Level of addition (wt-%) Capa 3050 Capa 4101 Both polycaprolactones lead to a better resistance towards permanent scratches up to 50% improvement with 4-functional Capa
Capa in 1K HMMM Formulations Set parameters Polyol Acrylic Capa Polyols Crosslinker (HMMM) Cymel 303* Varied parameters Acrylic polyol ref 70-100% Capa Polyols 0-30% Solvent Catalyst BuAc ptsa Mw of Capa polyols 400-900 Branching of Capa polyols 2-3 Solid content 73% Polyol/melamine (solid) 80/20 H-value of Capa Polyols (mg KH/g) 135-280 Curing 150 C, 10min * Cytec General properties Excellent appearance/compatility Good hardness Excellent chemical resistance A winning formula for performance
mm mm Capa in 1K HMMM Flexibility 5 4 3 2 1 0 Erichsen flexibility Effect of increasing concentration of Capa Polyols 0 20 30 Capa Polyols - wt% CAPA 2043 CAPA 3091 5 4 3 2 1 0 Erichsen flexibility Effect of M w of Capa Diols (20%) CAPA 2043 CAPA 2054 CAPA 2085 400 550 830 Capa Diols - M w (g/mol) Significant effect on flexibility due to flexible aliphatic chains Influenced by both amount and length of Capa A winning formula for performance
inchlbs Capa in 1K HMMM Impact resistance 9 8 7 6 5 4 3 2 1 0 Impact resistance Effect of increasing concentration of Capa Polyol 0 10 20 30 Capa Polyol - wt% CAPA 2043 CAPA 3091 Significant increase of impact resistance due to flexible aliphatic chains A winning formula for performance
Relative gloss recovery (%) Capa in 1K HMMM Self healing Gloss recovery Method: Scratching: 25 double rubs with scotch brite Recovery: 60 min @ 60 C 60 50 40 30 20 10 0 Gloss recovery - 20 Effect of increasing concentration of Capa Polyol 0 10 20 30 Capa Polyol - wt% CAPA 2043 CAPA 3091 Significant improvement of gloss recovery Semicrystallinity, less internal stress and viscoelastic properties of cured coating A winning formula for performance
Technical benefits Conclusions Caprolactones are aliphatic, liquid, solvent free, low viscosity (polyester)polyols resin modifiers suitable as reactive diluents or reactive coalescing agents Properties of polycaprolactones in crosslinked coatings High gloss and good appearance Low viscosity low VC Excellent outdoor durability Excellent low temp flexibility and impact resistance Excellent abrasion resistance Excellent scratch resistance Possible self healing effect Due to semicrystalline, viscoelastic aliphatic structures with low Tg created by caprolactone segments Benefits can be obtained without compromising on chemical resistance and final hardness.
Final conclusions Polycaprolactones in 2K PUR Caprolactones are versatile tools to improve existing coating formulations Resin modifiers replace 5-20% acrylics or polyesters Easy to add Use to alter overall formulation properties Regarded as conventional raw materials but formulations should be balanced in order to take advantage of the unique properties from aliphatic structures with low Tg and relative high H-number Can be used in automotive coating, protective coatings (windmills), aerospace coatings, transportation coatings Many properties more pronounced in WB systems Caprolactones improve sustainability by prolonged life-time and reduced emissions Perstorp continues to develop new grades meeting customer needs Capa polyols can be very versatile tools (as resin modifiers) in a coating formulators toolbox