New Self-Crosslinking NMP-free PUDs. Anthony Pajerski, George Ahrens, Lubrizol Advanced Materials, Inc., USA

Transcription

1 New Self-Crosslinking NMP-free PUDs Anthony Pajerski, George Ahrens, Lubrizol Advanced Materials, Inc., USA Introduction Coatings for wood floors typically require severe service requirements. Typically you ll find this in high traffic areas such as in shopping centers; areas where floors are prone to combined chemical and mechanical attacks, such as in a pub or restaurant; and in places where floors that are subject to high degrees of frictional force stress, as in sports floors. Even residential wood floor may occasionally be subjected to higher levels of abuse, resulting from the occasional holiday party or a family dogs playful nature. Therefore wood floor coatings must have high surface hardness, very good chemical resistance, excellent durability (toughness) and abrasion resistance to maintain an optimal appearance. Polyurethanes have demonstrated their ability to provide long lasting performance on floor substrates and, in particular, on wood where clear finishes are desired for aesthetic reasons. Polyurethanes are a unique class of polymers that have a combination of both hard and soft segment blocks within the same polymer chain. This combination results in a polymer that is able to demonstrate both high surface hardness and excellent flexibility; attributes that allow for the toughness required for abrasion, scratch and other wear resistance properties. Moreover, the strong hydrogen bonding between urethane and urea groups also contributes to improved wear properties as well as to excellent chemical resistance. These properties are serviceable over a wide temperature range for polyurethane where other polymers may become to brittle or soft and lead to failure 1-3. Ever stricter government regulations limiting the VOC of coatings in general has challenged coating raw material suppliers to maintain performance, if not improve them for their products. The public desire for lower impact on both environment and human safety, particularly in closed environments (high rise office for example), has led to industry certification standards such as GREENGUARD ( and Green Seal ( that limit the amount and type of residual volatiles. This is a particular difficult task in coatings that need to demonstrate high hardness and performance. One also needs to take into consideration the fact that on-site application of coatings to floors restricts potential use of energy to assist in the film formation and curing process; indeed typical requirements for wood floor finishes require serviceable film formation temperatures down to 4 O C. Wood being a porous substrate can further add to this challenge. From the above considerations, PUDs (waterborne polyurethane dispersions) would appear to be the option of choice for low VOC on-site flooring application. NMP (n-methyl pyrrolidone) is typically used as a processing solvent and coalescent for PUDs; NMP performs very well in both these respects due to its excellent solvating power and water miscibility. However, health hazard information on NMP has lead to new labeling requirements in the EU, and to increased scrutiny in the US resulting in many customers looking for NMP-free products This paper discusses the technical challenge and potential approaches to developing environmentally and user friendly waterborne polyurethanes for wood floor coating applications for the strictest requirements.

2 Processing Challenge When one looks at the PUD process, introduction of VOCs can come from two sources: 1) any processing solvent that is used in order to maintain a reasonable processing viscosity for PUD production; 2) any volatile tertiary amines that are used as a neutralizing agent for the common anionic/acid dispersing groups used. The schematic below shows the typical pre-polymer mixing process 2 that is used commercially to prepare PUDs and the stages where cosolvents and volatile amines are introduced. COOH HO OH + OCN NCO + HO OH + Diluent Polyol Poly-isocyanate 1) Neutralize 2) Water Water Dispersing Group Process Aid (viscosity control) OCN H 2 N NH 2 NCO x Urethane Formation Urea Formation Waterborne Polyurethane Dispersion x z Figure 1: Schematic of typical waterborne polyurethane synthesis In order to have a polyurethane coating that is able to work (i.e. form a coherent film) at 140g/L or less and at temperatures as low as 4 O C (or possibly more practically 10 O C/ 50 O F) one needs to start with a polymer that has a very low or more advantageously no VOC prior to formulation. A lower starting VOC content will allow the formulator more latitude toward obtaining an optimal product in terms of both film formation and performance at a particular VOC level; with more additives and cosolvents options. Several approaches can be considered in preparing an NMP free low VOC waterborne polyurethane by the prepolymer process described, where the prepolymer formation step produces urethane groups (isocyanate-hydroxyl reaction) while the chain extension step (isocyanate-amine reaction) in the water dispersed phase produces urea groups. If one can avoid the use of a processing solvent, then potentially unnecessary added VOC s can be avoided; however, this is typically possible only with PUDs that contain low degrees of hard segment (low urethane content). This is due to the higher urethane content leading to a higher degree of hydrogen bonding between oligomers/polymers and consequently higher viscosities at reasonable processing temperatures. PUDs with low hard segment content (or a low degree of hydrogen bonding, possible also due to steric effects) are typically not associated with hard or high performance coatings but more typically soft or adhesive grade polyurethanes. A second approach would utilize an acceptable amount of an alternative solvent (such as dipropylene glycol dimethly ether) or the use of a high boiling solvent or plasticizer that would not be considered a VOC or combination thereof 4. But this approach tends to limit the formulation latitude, applies synthetic

3 limitations, typically adds to system cost and potentially gives inferior performance if too much non-volatile diluent is used. A third approach plays on the prepolymer process using a volatile solvent as the processing aid, referred to as the solution or acetone process 2. This approach is reported to give very good results, but one is limited in the processing/reaction temperatures used due to the low boiling points of the diluent (such as acetone) and the use of specialized equipment required. Moreover, the acetone needs to be removed by vacuum distillation and either disposed of or recycled, which adds to processing costs by increasing processing time and energy. Furthermore the low flash point of acetone makes for additional safety risks which must be addressed. An additional approach that is used successfully in commercial situations is to employ reactive diluents (such as acrylates and methacrylates 5) which can act to control process viscosity, but can then be converted into a non volatile polymer after the PUD processing is completed. Of course, the reactive diluent approach also has potential disadvantages in lengthened process times and performance issues. However, skilled use of the reactive diluent process can minimize potential disadvantages and possibly lead to added benefits in to the final polymer performance. Film Formation Challenge High performance floor coatings require high surface hardness in order to withstand the physical wear and tear that they will be subjected to. Typically this hardness will correlate to >71 Konig oscillations (>100 Konig sec). An advantage of PUD based coatings is their ability to demonstrate high surface hardness at low cosolvent content. This is in contrast to other conventional polymeric coatings where the Tg dictates the surface hardness and also to a large extent the amount of cosolvent required to form a coalesced film. Waterborne polyurethanes differ in this respect due to a couple of main characteristics. One of these is the hard and soft segment copolymer character of polyurethanes and the associated phase separation into hard and soft domains that can occur. The degree of phase separation is dependent on a number of factors but can contribute to significant performance enhancement 6. The concept of polyurethanes block copolymer nature and phase separation is shown in Figure 2 below. There is also evidence that waterborne polyurethanes have a porous nature due in large part to the synthetic technique and raw material choices used to produce them. This porous quality is theorized to allow for internal plasticization of the polyurethane particle with water, which further aids film formation (see Figure 3 below) 7. After the drying process, water and any other volatiles such as neutralizing amines (which significant impact the hydrophilic characteristics of the polymer when ionized with the polymer acid groups), are released, the films then tend to be hard and water resistant if properly designed. The degree of phase separation in PUDs is intuitively less than one would find in solventborne polyurethanes, thus water plasticization may have more of an impact 7. Raw material choice is also of obvious importance in having a good balance of high hardness at low formulation VOC demand while delivering a high degree of performance. Indeed, one can envision a waterborne polyurethane (or other polymer type) that has good film formation characteristics and is very hard but has poor performance or resistance properties due to the polymers solution-like characteristics in water. Typically aliphatic polyisocyanates are used due to their stability toward light; however, if a degree of yellowing is acceptable, aromatic polyisocyanates can provide significantly better performance at a lower cost particularly MDI (methylene diphenyl diisocyanate). For aliphatic polyisocyanates hydrogenated MDI is used for its performance though it is rather rigid molecule, while hexane diisocyanate is the polyisocyanate of choice to impart greater flexibility to the hard segment

4 Hard segment {(HS) or urethane block Diisocyanate Chain extender Soft segment (SS) Figure 2. Schematic of polyurethane block copolymer structure and phase separation. - COO COO Water-rich areas Figure 3. Schematic model of an aqueous anionic polyurethane particle and the open/swollen morphology containing water rich areas. Due to the limited variety of commercially available polyisocyanates, much of the synthetic flexibility and design comes from the choice of polyol soft segment or other lower MW diols that can be incorporated in the hard segment. A number of polyol choices exist including polyethers, polyesters, polycarbonates, polybutadienes and polysiloxanes. Through judicious use of these polyols one can change the hydrophobicity or other chemical characteristic of the polyurethane as well as its flexible-rigid balance. Furthermore, by choosing polyols of particular MW and potentially combining them with short chain diols (such as butane diol or cyclohexyl dimethanol among others) one can tune both the hard soft segment balance along with the blockiness (length of blocks and mixing) that has the expected large impact on final properties and in particular film formation. Polyester polyols are of particular utility in PUD design and synthesis due to the variety of diols and diacids that can be combined to produce various performance qualities. Even with the excellent film forming characteristics of PUDs, it remains a formidable challenge to attain the necessary hardness at VOC levels of 140g/L or less given that we are targeting the performance of floor coatings that conventionally require crosslinking of some type as found for the more popular current high-performance commercial products. Performance Challenge Options are available to formulators for improving the performance of waterborne thermoplastic polyurethanes through the addition of a crosslinking agent for the polymer. Among these, polyaziridines and polyisocyanates have found significant commercial application in contractor applied wood floor coatings; mainly due to their effectiveness to cure at ambient conditions in a reasonable length of time, having a reasonable pot life and providing the desired level of performance. But both polyaziridines and polyisocyanates have safety concerns when handling these materials 8. For room temperature 2K polyisocyanate crosslinked PUDs, the self-condensation via reaction with water is the primary reaction that results in IPN formation and improved performance 9. Polyisocyanates crosslinkers in waterborne

5 polymers have a shorter pot life than polyaziridines due to their reactivity with water, closer to ~4h for optimal performance, after which time the resulting dispersion becomes unusable either due to unacceptable performance, appearance or application properties. Furthermore, the above described reaction of the polyisocyanate with water can generate foam that may become entrapped in the final coating. Lubrizol s goal is to provide products that are not only environmentally friendly but also allow the end user to work with the material in the safest manner possible along with easy and smart application properties. Ideally, this provides optimal chance for a quality final application with minimal waste of material, time and money. Lubrizol continues to pursue chemistries that allow for a stable one component coating solutions where the coating can be cured at or below room temperature and deliver the performance of traditional 2K coatings. A few viable options exist to incorporate functional groups into waterborne polyurethanes that can auto-crosslink at room temperature upon application and have the potential to provide a shelf stable system as discussed below. Fatty acid moieties obtained from natural oils high in unsaturation such as linseed, sunflower, soybean, tung and safflower oils can be incorporated into PUD s that can crosslink upon exposure to oxygen. The fact that some of the raw materials used for oxidative crosslinking are plant-sourced gives it a green appeal. Auto-oxidative crosslinking goes through a number of intermediates and leads to a large number of final chemical structures. The main crosslinking reaction is believed to be the coupling of free radical oxygen atoms 10, 11. Oxidative curing typically requires the addition of a drier or catalyst to push the cure and optimally the use of conjugated polyunsaturated oils. The driers tend to be based on heavy metals that can be toxic, highly colored, difficult to incorporate into waterborne polymers and easily affected by other components in the waterborne polymer or externally such as the tannins in wood. Moreover, significant amounts of drier along with a resin having a high content of fast drying conjugated unsaturated groups typically leads to final dispersions and coatings with a high degree of color The structure of waterborne oil modified polyurethanes are also more brittle than conventional polyurethanes due to less effective polymer alignment and packing, likely analogous to the effect of the side chains in poly(meth)acrylate type polymers. Nucleophilic reactions on carbonyls are also employed in waterborne polymer crosslinking and can provide significant improvement in various resistance properties of polyurethanes. However, it has been noted that the chemistry suffers from sub-par water resistance in the cured coatings 12. The nucleophilic addition of amine/hydrazides with carbonyls is triggered by a drop in ph and loss of water seemingly making it well suited for anionic polymer dispersions. Acetoacetoxy functionality could be used which is crosslinkable either by enamine formation (such as with polyamines) or Micheal reaction by nucleophilic addition to a Micheal acceptor such as an acrylate group (typically base catalyzed). These reactions can be rapid and very effective means of crosslinking. However, issues revolve around hydrolytic stability of the ester typically used to incorporate the acetoacetoxy group, premature crosslinking and the potential to obtain undesirable color in the dispersion and applied coating 13, 14. The formation of the color/chromospheres is likely related to the reaction of various amines with the acetoacetoxy groups 14, 15, some of which are typically present in polyurethane synthesis. Final performance (and likely VOC demand) is also related to how a coating dries. In other words, does the process happen in a homogeneous manner or non-homogeneous process such as where the surface dries/cures faster than the underlying coating layers? There have been cases described in autooxidative cure coatings where the surface dry occurs more quickly than the underlying material, resulting in surface defects or wrinkling. However, this has also been considered a possible advantage providing a path toward a self-healing behavior due to the potential that the underlying material could cure later after wear has occurred. Faster surface dry might also lead to entrapment of solvent leading to poorer performance of the coating, particularly in the short term; self-crosslinking likely will further aggravate this situation. It can be difficult to determine non-optimized coating drying processes except by simply relating affects such as final performance and open time. Quantitative methods do exist for understanding how homogeneous the film formation process is 16. For on site floor application the film formation process would need to be robust enough to allow for it to occur over a wide range of temperatures and humidities. Work in this area is on-going at this time

6 Experimental Formulation: The Lubrizol NMP-free 1K self-crosslinking PUD was formulated with 11.1% diproplylene glycol n-butyl ether versus polymer solids and reduced to 30% solids; the final dispersion has a VOC of ~139 g/l and is a film former at 4.4 o C (40 F) at 50% humidity on unsealed chart paper (porous substrate). The NMP containing 1K self-crosslinking PUD was formulated with 13.7% diproplylene glycol n-butyl ether versus polymer solids and reduced to 30% solids; the final dispersion has a VOC of ~269 g/l and is a film former at 4 o C on uncoated paper. Commercial 2K PUDs controls were purchased from a local contactor supply outlet and used as is; the containers indicated that the VOC/s are <350g/L. The coefficient of friction (COF) for the 1K self-crosslinking and commercial 2K crosslinked PUDs were determined to be between as tested. Chemical resistance: Uses ASTM method D Coatings are tested by applying three coats of similar weight to maple veneer panels that are cured for the designated time (typically 7 days) at ambient conditions before being tested. One hour spot tests are typically run on the surface of the finish. Tests for specific applications or customer end use may dictate longer exposure times. Sections of cotton facial pads are soaked with the test agent on the surface of the finish and covered using either watch glasses or a similar devise to keep the test agent from evaporating. After removal of the pad and test agent, the surface of the coating is blotted dry and observed for damage. The tested surface is re-evaluated after a one hour recovery. Ratings are 5 = no effect on finish. 4 = finish is slightly swelled or surface of finish is permanently changed. 3 = finish surface is changed and wood color has been impacted. 2 = more severe damage than 3. 1 = very severe damage to film and/or discoloration of wood. 0 = finish is removed from substrate. Black heel mark, mar and scuff resistance test: The apparatus consists of a pivoting metal pendulum arm with a 2lb weighted piece of hard black rubber (such as that of a hockey puck) at the end meant to simulate a hard shoe sole capable of producing black heel markings. This is the striking surface to the test panel. The test consists of striking the coated maple panel six times on different areas and directions on the panel with the pendulum black heel marking device. Striking is done by raising the pendulum arm to an angle of degrees of the coated panel which is placed on the floor and then releasing the arm under the force of gravity to strike the coated panel. The black heel hits the panel with a calculated force of ~50lb/in 2. Results are expressed by visual assessment (scratching, scuffing, and black markings/discoloration) and gloss measurements. Coatings to be tested are prepared by applying three coats of similar weight to maple veneer panels that are cured for the designated time (typically seven days) at ambient conditions before testing. Abrasion Resistance: Uses ASTM D 4060 on wood panels. Pairs of panels are finished with three coats of the test subject and aged seven days at ambient conditions. Actual Taber testing is performed in a climate controlled environment (70 F/50% RH). Te st panels are conditioned to this environment for 16 to 24 hours before test is performed. Taber test is performed using CS17 wheels. Each test panel is weighed initially and after each 250 cycles on a scale that measures to four units to the right of the decimal point. Each panel is run for a total of 1000 cycles. Taber abrasion values are expressed as milligrams weight loss per 1000 cycles (averaged over the pair of panels). In the case of wear-through, the total cycles required for wear-through of the coating is recorded. Sport Floor Field Test: PUDs are applied with two coats of similar weight to the sports floor (typically a basketball or racquetball court) that was coated with a primer and allowed to dry for 24 hours before they are put back into play. Gloss readings are taken of each coating at a set matrix of positions on the test floor; 60 gloss readings are taken initially befor e the floor is put in use and once every two weeks after that. The gloss meter test areas are mapped to insure that the same location is read each time a reading is taken. Solvent Swell: Data generated for solvent swells were based on dispersions at ~30% solids drawn-down 10 mil wet on Mylar film that was pre-coated with a Teflon release coating. The resulting films, ~2mils dry, are cured for a given time period (1 day or 7 days) at ambient conditions after which time a 25 mm diameter circular film is punched out using a die. The 25 mm circular film sample obtained after removal from Mylar backing is then submerged in the solvent being tested in a covered small glass jar for a 24 hour time period before being tested for swell. Solvent swell was determined by measuring the diameter of the swollen film in a Petri dish containing some of the solvent (to maintain swell size) using digital calipers and double checked with a standard metric ruler.

7 Discussion of Results We evaluated our progress on designing an effective 1K NMP free PUD that could be formulated for low VOC applications (<140g/L) by comparing it with a more conventional NMP containing 1K (selfcrosslinking Lubrizol PUD at 270g/L) and 2K PUD commercial floor finishes (contractor grade, ~350g/L). The results of which are discussed below. Chemical Resistance: For adequate protection against commonly used cleaners, food stuffs and alcohol-based materials, floor coatings need to have excellent resistance properties in order to prevent unsightly stains and blemishes to the coating as well as to the substrate. A number of materials expected to be potentially encountered in residential and commercial wood floor coating applications were evaluated. These were assessed on the low VOC NMP-free self-crosslinking PUD and compared against a higher VOC NMP based self-crosslinking PUD and two commercial two components (2K) crosslinked controls based on polyaziridine and polyisocyanate crosslinkers. The exposure time of the coatings to the substance is given in parentheses next to the substance. As can be seen from the results shown in Table 1 illustrate; we were able to obtain results using a low VOC NMP-free PUD approach that is comparable to the higher VOC NMP containing self-crosslinking NMP based PUDs and commercial NMP containing 2K controls (aziridine and isocyanate crosslinked). Test 1K NMP PUD (270g/L) 2K NCO (350 g/l) 2K Aziridine (350g/L) 1K NMP-Free (140g/L) Water (16 hr) % Ammonia (1 hr) % Acetic Acid (1 hr) Mustard (6 hr) MEK (1 hr) % Ethanol (1 hr) % IPA (1 hr) Red Wine (6 hr) Overall Total Table 1: Chemical resistance of 1K self-crosslinking PUD versus 2K commercial controls after 7 days at room temperature (0 = highly damaged/coating removed, 5 = no damage). Solvent Swells (Degree of Crosslinking): Degree of crosslinking in a polymer can be determined in an objective by solvent swell measurements. The degree of swelling of the film by the solvent is related in large part to the degree of crosslinking. The swelled films are measured and compared to the starting film size, the lower the swell the more effective the crosslinking and solvent resistance. Several polar solvents were examined that are typically aggressive toward PUD coatings to determine consistency of results. To determine speed of cure we looked at the affect of cure time (one day versus seven days) at ambient conditions on solvent swell results. The results are shown in Table 2 below are consistent with the more subjective spot test and again demonstrate very good performance for the low VOC NMP-free 1K PUD. The 2K polyisocyanate crosslinked PUD gave the most significant improvement in crosslinked performance after one week cure time, particularly with respect to NMP swell. The self-crosslinking PUD did not show any additional improvement in solvent swell after the 1 day cure time suggesting a fast crosslinking reaction upon film formation.

8 Cure Time at RT- Solvent 1 Day RT Cure NMP 1K PUD (270g/L) (% Increase) 2K NCO PUD (350g/L) (% Increase ) 2K Aziridine PUD (350g/L) (% Increase) 1K NMP Free PUD (140g/L) % Increase MEK (slight white) Methanol 4 20 (slight white) 8 12 NMP Day RT Cure MEK (slight white) Methanol 4 12 (slight white) 8 12 NMP Table 2: Results of solvent swell of films in terms of increase in size after designated cure time. Black heel mark/scuff resistance: A recognized performance aspect of wood floor coatings is their ability to resist scuff marks from shoe soles, often termed black heel mark resistance (BHMR). Along with scratching or abrasion, shoe sole scuffing represents one of the main modes of floor failure in terms of changes in gloss and esthetics. In commercial settings such as retail stores or restaurants - where down time needs to be minimal and that undergo heavy customer traffic - the cure also needs to be relatively quick. The pendulum black heel mark (BHM) and scuffing device test, described in the experimental was used to test the self-crosslinking PUD against the contractor applied 2K PUD wood floor finishes used in previous experiments. Results for pendulum BHM test results obtained are displayed in Figure 4 and demonstrate that that self-crosslinking PUD performance is on par with the premium grade contractor applied commercial 2K PUD systems (all gloss finishes). This was true for both ambient and Cleveland condensation cabinet (CCC) conditions. Figure 5 demonstrates actual tested panels on a microscopic view were one can note the melt and flow appearance for an un-crosslinked PUD wood coating that gives poor BHMR results; the NMP-free 1K PUD being similar to the 1K NMP PUD Black Heel Mark Rating Rating K NMP PUD 1K 2K NMP-Free Aziridine PUD 2K NCO 2K Aziridine Gloss) Ambient BHM CCC BHM Figure 4. Black heel mark resistance of Lubrizol 1K self-crosslinking PUD vs. commercial 2K crosslinked wood finishes; at ambient and at 120F/100% humidity conditions (10 = no damage)

9 Uncrosslinked PUD 1K NMP PUD 2K NCO Crosslinked 2K Aziridine Crosslinked Figure 5. Microscopic view of coating deformation observed from BHMR test demonstrating a melt and flow behavior for the 1 st Gen 1K coating with poorer BHMR results. Wear/Abrasion Resistance: Abrasion resistance remains a key lab bench test for predicting performance of floor coatings. Polyurethanes typically give good abrasion resistance. After crosslinking the coating, it needs to retain abrasion resistance and the ability to withstand scratching that would be experienced by a floor coating. Figure 6 below illustrates the data obtained for gloss formulas of the new Lubrizol NMP-free 1K PUD in comparison to the commercial 2K PUD floor coatings using a polyaziridine or polyisocyanate crosslinker. The abrasion resistance data was examined by mg coating loss per 1000 cycles. The NMP-free 1K PUD provided excellent result in comparison to the 2K commercial finishes and the NMP containing 1K PUDs Milligrams Wt. Loss/1000 Cycles NMP 1K NMP-Free 1K PUD 2K Aziridine 2K NCO Low Average High Finish Figure 6: Tabor abrasion data for 1K PUD s versus commercial 2K crosslinked polyurethane wood floor finishes (ASTM D-4060, with 1000g weight 3 coats on maple at similar total coat weight)

10 We field tested the 1K NMP PUD against the commercial 2K aziridine crosslinked PUD on a heavily played racquetball court to determine if the lab bench test accurately predicted the actual real floor wear behavior. The court was split in half from front to back with each PUD coating applied in three on to each half court. The average gloss retention was measured across the entire floor in a defined matrix every two weeks; the results of the sport floor test are shown in Figure 7. The coatings show a loss of gloss over the first six weeks and then they appear to both plateaus. It should be noted that the second generation 1K PUD was coated on the right side of the court which receives more wear due to the court door entrance located there as well as expected players behavior patterns. Lubrizol s in the process of field testing the new NMP-free 1K PUD as well as basketball court field tests of other 1K PUDs to further confirm performance. A view of the racquetball court at the 10 week in service period is shown in Figure 8 and illustrates comparable wear performance between the 1K NMP PUD and the commercial 2K aziridine crosslinked PUD. Based on the bench results, Lubrizol expects the NMP-free 1K to perform in a similar manner to the coatings shown in Figure Average 60 Gloss K Aziridine 1K NMP PUD Exposure Time in Weeks Figure 7: Sport floor performance of Lubrizol 1K PUD versus a premium commercial grade 2K aziridine crosslinked PUD (gloss formula) as measured by average 60 gloss vs. in service time. Figure 8: Picture of sport floor at 10 week service; 2K aziridine crosslinked PUD on left and 1K NMP PUD on the right.

11 Summary and Conclusions Lubrizol recently developed a new 1K NMP-free polyurethane dispersion technology that can be formulated at 140g/L and demonstrates performance comparable to that of premium commercial 2K PUD contractor applied wood floor finishes (with ~350g/L VOC). Performance of the new 1K NMP-free PUD was evaluated in terms of chemical resistance, solvent swell, scuff or black heel mark resistance (under a range of conditions) and abrasion resistance against commercial two-component crosslinked waterborne polyurethane coatings along with current commercial 1K PUD floor coatings. These lab bench top tests found comparable performance for the Lubrizol 1K PUDs versus the commercial 2K (polyaziridine and polyisocyanate) crosslinked PUD controls. Sport floor field test data obtained thus far supports the lab bench top test results that the performance of the Lubrizol 1K PUD is on par with commercial 2K PUD wood floor coatings. Solvent swell further supports the chemical and wear resistance tests that the 1K NMP PUD was providing fast and effective crosslinking within the coated films in comparison to the 2K PUDs. The advantages of the new self-crosslinking 1K NMP-Free PUD lies in its user friendliness which eliminates potential for waste and performance issues resulting from poor mixing and limited pot life, along with health issues related to handling the crosslinking component. Combined with the fact that the new 1K self-crosslinking PUD is easy to apply and quick to dry, the end user can save time and money for on site wood floor coating applications. References 1. Dietrich, D, Adv. Org. Coat., Sci. Technol. Ser., 1, 55, Rosthauser, J. W.; Nachtkamp, Klaus. Waterborne Polyurethanes, Advances in Urethane Science and Technology, 10, , Tirpak, R.E; Markusch, P.H., Journal of Coatings Technology, 58, 49, WO02/08327A1 5. US ; US Oertel, G; Polyurethane Handbook, Hanser, Satguru, R; McMahon, J; Padget, S.C.; Coogan, R. G.; Journal of Coatings Technology, 66, No. 830, March Dhimiter Bello et al; American Journal of Industrial Medicine; Vol.46, Issue 5, , Hesselmans, LCJ; Derksen, A.J.; van den Goorbergh, J.A.M., Progress in Organic Coatings, 55, 2, , Brown,C.E.H, Journal Col. Chem. Assoc., 40, 1027, Oyman, Z.O., Toward Environmentally Friendly Catalysts for Alkyd Coatings, Thesis, Eindhoven University, Tennebroek, R.; Geurts, J.; Overbeek, A.; Harmsen, A., Surface Coatings International, 83(1), 13-19, Geurink, P.J.A.; vandalen, L; van der Ven, L.G.J.; Lamping, R.R., Progress in Organic Coatings, 27, 73-78, US2006/ Eastman Chemical technical publication; N Glover, P. M. ; Aptaker, P. S.; Bowler, J. R.; Ciampi, E.; McDonald, P. J, Jounal of Magnetic. Resonance, 139(1), 90-97, 1999