Ambient temperature curable isocyanate-free compositions for preparing crosslinked polyurethanes

Abstract

The present invention provides a multicomponent composition that is substantially isocyanate-free and comprises a polycarbamate as a first component having a filler, pigment, extender or matting agent and a second component containing an acidic catalyst an alkanol having one OH group, a polyaldehyde and an acetal or hemiacetal of the polyaldehyde. The compositions are shelf stable and useful as two components and avoid problems caused by combining the catalyst with any filler, pigment, extender or matting agent.

Claims

1. A substantially isocyanate-free two-component composition having a pH of 7.0 or less comprising: as a first component, one or more polycarbamate having two or more carbamate groups, and one or more polymeric matting agent, filler, extender, or pigment in the amount of from 1 to 80 wt. %, based on the total solids of the first component, and, as a second component, from 5 to 90 wt. %, based on the total weight of the second component, of one or more alkanol having one OH group, one or more polyaldehyde that has two or more aldehyde groups, or one or more acetal or hemiacetal of the polyaldehyde, and from 0.01 to 10 wt. % of one or more catalyst having a pK.sub.a of less than 5.0, based on the total weight of solids in the composition, said composition having less than 5 mol % of isocyanate (NCO) groups based on total moles of carbamate groups plus isocyanate groups in the composition; wherein the first and second components when combined form a composition that reacts to cure at a temperature of from 0 C. to less than 80 C. to form a crosslinked polyurethane.

2. The two-component composition as claimed in claim 1, wherein the alkanol having one OH group is a primary alcohol.

3. The two-component composition as claimed in claim 1, wherein the catalyst is an organic or inorganic protic acid or salt thereof.

4. The two-component composition as claimed in claim 1, wherein the catalyst is a sulfonic acid.

5. The two-component composition as claimed in claim 1, wherein in the first component of the composition, the polycarbamate is the condensation product of one or more polyols with an unsubstituted carbamic acid alkyl ester or urea.

6. The two-component composition as claimed in claim 5, wherein the one or more polyols is an acrylic polyol, or an alkyd polyol.

7. The two-component composition as claimed in claim 1, wherein in the second component of the composition, the polyaldehyde from which the acetal or hemiacetal is formed preferably has a solubility in water of less than 0.15 gram of polyaldehyde per milliliter of water at 25 C.

8. The two-component composition as claimed in claim 1, wherein the polyaldehyde in the second component is chosen from (cis,trans)-1,4-cyclohexane dicarboxyaldehydes, (cis,trans)-1,3-cyclohexanedicarboxyaldehydes and mixtures thereof.

9. The two-component composition as claimed in claim 1, comprising one or more pigments, fillers or extenders chosen from any metal oxides, metal carbonates, silica, and alkali metal silicates.

10. The two-component composition as claimed in claim 1, wherein the blend ratio of the first component to the second component from is from 2:1 to 5:1 by weight.

11. The two-component composition as claimed in claim 1, wherein the one or more polyaldehyde is a dialdehyde.

12. The two-component composition as claimed in claim 1, wherein the one or more polyaldehyde is a cyclic dialdehyde.

13. The two-component composition as claimed in claim 1, wherein the one or more polyaldehyde is a cycloaliphatic dialdehyde.

Description

EXAMPLES

(1) The following examples illustrate the present invention. Materials: If not identified in Tables below, the materials used in the Examples of the present invention are, as follows: Polycarbamate A: Carbamate polymer of 1,3-Benzenedicarboxylic acid, 2-ethyl-2-hydroxymethyl-1,3-propanediol, dodecanoic acid and (9Z)-octadec-9-enoic acid.

(2) CHDA: Mixture of 1,3 and 1,4 cyclohexane dicarboxaldehydes.

(3) Alkyd Polycarbamate: Product of modified alkyd polyol.

(4) Two Stage Alkyd Polyol Synthesis:

(5) First Stage: Alcoholysis. To a 5 L three-neck round bottom flask was added sunflower oil (1388.9 g). A glass stir rod and paddle were placed in the middle joint of the flask. The flask was attached to a lattice with overhead stirring, and an oil bath at room temperature was raised to submerge the flask. The setpoint on the bath was 220 C. and heating and stirring were started. To the stirred oil, pentaerythritol (713.6 g) and dibutyltin catalyst (1200 ppm on total reactor charge were added. Once all reactants were added, a packed condenser with a set point of 95 C. was attached to one of the side joints and topped with a hose adaptor that was connected to a bubbler. To the other side neck, a second hose-adaptor was attached and connected to a nitrogen inlet. A slow nitrogen sweep was placed on the system and observed in the bubbler. The reaction mixture was allowed to heat and mix overnight to ensure high conversion. This stage was completed when a monoglyceride of the sunflower oil was achieved, meaning that the reactor contents homogeneously dispersed in methanol at one part resin to three parts methanol.

(6) Second Stage. The 5 L three-neck flask containing the alcoholysis mixture from the first stage was equipped with a glass stir shaft and paddle. The flask was attached to a lattice with overhead stirring. An oil bath at room temperature was raised to submerge the flask. The set point on the bath was 220 C. and heating and stirring were started. To the flask, isophthalic acid (359.0 g), phthalic anhydride (538.5 g), and xylenes (2 wt. % on total charge) were added. Then, a Dean-Stark trap was connected to one of the side joints and topped with a Friedrichs condenser connected to an outlet bubbler. A nitrogen sweep was placed on the system. The system was allowed to heat (220 C.) and the water formed was distilled out as an azeotrope with xylenes. This second stage of the reaction was monitored by removing samples from the reactor and titrating the acid value (AV). The reaction was allowed to progress until the desired AV (8.0 mg KOH/g) was reached. The alkyd polyol had a measured OH number of 180 mg KOH/g (on solids). Then the reaction contents were poured into a glass jar and allowed to cool to room temperature under a pad of nitrogen.

(7) Alkyd Polycarbamate Synthesis:

(8) A reaction was carried out in a 2000 ml round bottom reactor system equipped with a mechanical stirrer, reflux condenser, nitrogen gas purge system and temperature control. A heating mantle was used for temperature control. The reactor was charged with the alkyd polyol (2000 g) from above, diluted to a final solids level of 60-70% in xylene, to achieve a process viscosity which allowed efficient stirring at 140 C. The catalyst, Fascat 4201 dibutyl tin oxide (DBTO, Arkema, Inc., Philadelphia, Pa.), was added to the alkyd polyol in the reactor at 0.6 wt. % on solids. The amount urea (99.5 wt. % pure, Sigma-Aldrich, St. Louis, Mo.) used was calculated based on the hydroxyl value for the alkyd polyol to target 62% conversion of the hydroxyl groups. For the 2000 g batch of alkyd polyol, 238.7 g total of urea was first dissolved in distilled water to make a 50 wt. % aqueous solution. The alkyd-solvent-catalyst mixture in the reactor was slowly heated to 140 C. and nitrogen purged for at least 30 min. Urea solution was loaded into 60 ml glass syringes and was carefully fed into the reactor at a constant controlled rate through a syringe pump. The urea solution was steadily fed into the reactor over 6-10 hrs. Azeotropic vapor was formed and cooled in the condenser, which was then collected in the Dean-Stark trap. 5. The reaction was carefully maintained at 140 C., mixing at 500-600 rpm and continued for 10-12 hr. until completion. Samples were taken periodically for NMR and GPC analysis. The Carbamate Conversion (from hydroxyl to carbamate) was calculated at 66%.

(9) Dibutyltin oxide is purchased from the Aldrich Chemical Company.

(10) Luperox tertiary-amyl 2-ethylhexyl peroxycarbonate (TAEC), a radical initiator, is purchased from Arkema. Inc., Philadelphia, Pa., USA.

(11) Steel plates are Act Test Panels, Cold Roll Steel, smooth and clean, having dimensions of 4 inches by 12 inches by 0.02 inch (i.e., 10 centimeters (cm) by 30 cm by 0.05 cm).

(12) Poplar wood boards are Home Depot poplar, having dimensions 3.5 inches by 5 inches (8.9 cm by 13 cm), cut from 3.5 inches by 3 feet (8.9 cm by 91 cm) boards.

Examples 1 and 2: Performance and Stability of the Compositions

(13) TABLE-US-00001 TABLE 1 Compositions High Gloss High Gloss Clear Wood Clear Wood Finish with Finish with Example 1 Example 2 Raw Material Supplier wt. (grams) wt. (grams) First Component Polycarbamate A 49.15 47.93 n-butyl acetate Fischer Scientific 18.27 17.81 (Fair Lawn, NJ) BYK 399 Surface- BYK Chemie 0.05 0.05 active polymer, (Wesel, DE) silicone-free Second Component CHDA 5.67 8.02 Ethanol Fischer Scientific 25.58 24.94 (Fair Lawn, NJ) Nacure 1040 King Industries 1.28 1.25 (40% p-TSA in (Fair Lawn, NJ) iso-propanol) A + B 100 100

(14) The two component composition formulations identified in Table 1, above, were coated on an aluminum 7.6 cm by 15.2 cm metal substrate using a 152.4 micron (6 mil) gap bar and were cured by for 7 days in a controlled temperature at 23 C. (72 F) and relative humidity (50%) laboratory. To give coatings that were about 35-50 microns thick. The coatings were tested and the results are given in Table 2, below.

(15) Test Methods:

(16) Heat Aging:

(17) The second component was heat aged for 4 weeks @ 60 C. and was examined by visual inspection for gelation or phase separation.

(18) Dry Time:

(19) Determined by ASTM D5895 using a Gardco Electronic Ultracycle Circular Drytime Recorder 5000 series (Paul Gardner Company, Pompano Beach, Fla.).

(20) Thickness of the Coating:

(21) ASTM D7091-05 (Standard Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals (2005)).

(22) Gloss:

(23) Measurements are made with a BYK Labotron Gloss Unit following ASTM D523-08 (Standard Test Method for Specular Gloss (2008)) and at the indicated angle of gloss measuring unit to substrate. An acceptable gloss result is retention of the initial gloss.

(24) Pendulum Hardness:

(25) According to the Koenig pendulum hardness test by following ANSI ISO1522:2006 (Pendulum damping test, (2006)). The hardness is measured after the indicated cure time at room temp and 50% relative humidity in seconds it takes to dampen pendulum swing. An acceptable result is from 50- to 150 seconds.

(26) MEK Double Rub Resistance:

(27) In Examples 3 to 3A, a MEK Rub test Machine (DJH Designs, Oakville, ON, CA) was used to evaluate coating resistance to methyl ethyl ketone (MEK) similar to ASTM D 4752-98 (1998). Coatings were cured at room temperature (24 C.) and 50% relative humidity for the indicated time. The tester moved a cotton pad, attached to a weighted block that applies a force of 0.155 Kg/cm.sup.2 (2.2 lb/in.sup.2), in a back and forth motion across the coated panel. Each back and forth is referred to as one double rub. Rubbing was continued until the indicated failure occurred, and that number of double rubs was recorded. Unless otherwise indicated, rubbing was continued until the coating was cut through and the substrate became visible in any area, and that number of double rubs was recorded. An acceptable result is at least 100-200 double rubs.

(28) Tape Crosscut Adhesion:

(29) Crosscut adhesion was measured and rated according to a modified version of ASTM D-3359-09 (2009) where a 10 cm piece of Permacel 99 pressure adhesive (3M, Minneapolis, Minn.) tape was laid over the indicated coating and a 3 mm blade was used to make a crosscut in testing how well the coating adheres to the substrate when the tape is pulled off. ASTM ratings range from 0 A to 5 A where a rating of 5 A is desired. According to the method, the scale reads as: 5 A (no peeling or removal); (4 A) Trace peeling or removal along incisions or at their intersection; (3 A) Jagged removal along incisions up to 1.6 mm ( 1/16 in.) on either side; (2 A) Jagged removal along most of incisions up to 3.2 mm ( in.) on either side; (1 A) Removal from most of the area of the X under the tape; and (0 A) Removal beyond the area under the tape. An acceptable result is 4 A or higher.

(30) Time to Sand:

(31) The sandability was determined by the time reached where using hand sanding, 320 grit sandpaper did not cake with primer and material was easily shaken or knocked off the sand paper. An acceptable result would be ability to sand the primer within an hour.

(32) Thermal Yellowing:

(33) Determined by applying a 380 micron thick wet film to a white ceramic tile. After one hour ambient cure, room temp and 50% relative humidity, the coated ceramic tiles were placed into a 60 C. oven for 24 hours. Cielab (L* a* b*) color measurements were taken before and after thermal cycle. The delta E of the coatings were calculated from the initial and final L* a* b* values. Delta E is equal to the square root of the sum of the square of (L*.sub.initialL*.sub.final).sup.2+(a*.sub.initiala*.sub.final).sup.2+(b*.sub.initialb*.sub.final).sup.2.

(34) The second component of Examples 1 and 2, formulated with catalyst was shelf stable after a 4 week heat age test was completed. No visible phase separation was observed. Other results are shown in Table 2, below.

(35) TABLE-US-00002 TABLE 2 Performance Results Dry Pendulum MEK Example time Gloss Hardness (sec) (dbl rub) Thermal Yellowing 1 (min) 20 60 85 4 hr 1 day 7 day 24 hr 7 day initial *b Delta *b Delta E Initial 23.33 84 96.3 96.2 28 170 188 163 >200 6.2 5.79 5.99 1 wk 26.67 85.7 97.2 98.3 73 103 105 152 >200 5.22 7.32 7.55 2 wk 22 88.6 97.4 98.6 78 138 178 167 >200 6.4 7.39 7.63 3 wk 25.33 85.1 96.4 99 59* 149 160 180 >200 5.69 7.38 7.63 4 wk 26.67 85.8 97.4 98.4 60 138 170 180 >200 5.98 7.39 7.62 2 (min) 20 60 85 4 hr 1 day 7 day 24 hr 7 day initial *b delta *b delta E Initial 22.33 88.2 97.5 97.9 49 185 199 143 >200 5.98 6.36 6.89 1 wk 23.33 87.2 97.1 98.5 35 106 108 141 >200 5.15 9.36 9.74 2 wk 25.33 85.9 96.6 98.9 49 117 171 165 >200 6.56 8.35 8.7 3 wk 20 90.1 97.6 99.1 44* 132 166 163 >200 5.98 8.03 8.42 4 wk 25.33 86.8 97.1 98.8 50 124 166 167 >200 6.24 8.37 8.65

(36) Even after the coating materials were left on the shelf for 4 weeks with the catalyst contained in the second component, the coating performance properties in Table 2, above, including drytime, hardness and MEK resistance tested within critical test requirements. Gloss was generally retained.

Examples 3 and Comparative 3A: 2K Formulation of a Primer Surfacer

(37) TABLE-US-00003 TABLE 3A Example 3, 2 Component Primer Surfacer Formulation Amount (g) Carbamate Component Alkyd Carbamate (54.9 wt. % in xylene) 75.2 (Equiv. Wt. of polyol to carbamylation = 315 on solids as determined by hydroxyl titration) Toluene (solvent) 42.9 MEK (solvent) 15.8 Disperbyk.sup.,1 BYK-110 (dispersant) 2.5 Tiona.sup.,2 595 Titanium Dioxide (pigment) 15.6 Nicron.sup.,3 Talc 665 15.6 Burgess Optiwhite.sup.,4 Calcined aluminum silicate 10.3 Barium Sulfate (pigment) 17.9 Diacetone alcohol (solvent) 4.2 Total Part A 200 Acetal Component CHDA (88 wt. active solids %) (Equiv Wt = 70 on solids) 9.4 Ethanol 29.2 Paratoluene sulfonic acid (40 wt. % in isopropanol) 1.5 Total Part B 40 .sup.1Byk Chemie, (Wesel, DE); .sup.2Cristal, Hunt Valley, MD; .sup.3Imerys, Overland Park, KA); .sup.4Burgess Pigment, Sanderson, GA.

(38) In each of Examples 3 and 3A (comparative), Primer Part A was prepared by overhead mixing using a Dyspermat mixer (VMA-Getzman, Reichshof, Del.). A Hegman gauge was to determine how finely ground the pigments are dispersed in the paint. The mixed paint had a value of 5.5 Hegman units. A solution of Part B was heat aged at 60 degrees C. for 4 weeks prior to use. Prior to spraying primer, 40 g of the heat aged Part B was added to Component A with stirring.

(39) TABLE-US-00004 TABLE 3B Comparative Example 3A 3 Component Primer Surfacer Formulation Amount (g) Part A - Carbamate Component Alkyd Carbamate (54.9 wt. % in xylene) 68.0 (Equiv. Wt. of polyol to carbamylation = 315 on solids as determined by hydroxyl titration) Toluene (solvent) 38.8 MEK (solvent) 14.3 Disperbyk.sup.,1 BYK-110 (dispersant) 2.3 Tiona.sup.,2 595 Titanium Dioxide (pigment) 14.1 Nicron.sup.,3 Talc 665 14.1 Burgess Optiwhite.sup.,4 Calcined Aluminum Silicate 9.3 Barium Sulfate (pigment) 16.2 Diacetone alcohol (solvent) 3.8 Ethanol 19.1 Total Part A 200.0 Part B - Polyaldehyde Component CHDA (88 wt. % active solids) (EW = 70 on solids) 9.4 Total Part B 9.4 Part C - Catalyst Component Paratoluene sulfonic acid (40 wt. % in isopropanol) 2 Total Part C 2 .sup.1Byk Chemie, (Wesel, DE); .sup.2Cristal, Hunt Valley, MD; .sup.3Imerys, Overland Park, KA); .sup.4Burgess Pigment, Sanderson, GA.

(40) Part A was prepared by overhead mixing using a Dyspermat mixer (VMA-Getzman, Reichshof, Del.). No heat aging was conducted on Part A. The resulting Hegman value of the primer was 5.5 or greater. Prior to spraying the primer, Part B was added to Component A with stirring followed Part C.

(41) Coatings Application:

(42) The Example 3 and 3A primer was sprayed in two coats, with a 10 minute flash time in between each coat. The time to sand was measured after the second 10 minute flash of the second applied coating. The coating was applied to cold roll steel panels sanded with 80 grit sand paper.

(43) For panels with base and clear coats, the base and clear coat were applied after the primed panels were sanded. A commercial black base coat was then applied after the panels were sanded according to manufacturer's recommendations. A commercial clear coat (2 coats sprayed) was applied over the base coat according to the manufacturer's recommendations. The panels were cured overnight at room temperature prior to evaluations.

(44) TABLE-US-00005 TABLE 4 Time to Sand the Primer Comparative Example 3A (3K) Example 3 (2K) Time to Sand 40 40 Primer (min)

(45) As shown in Table 4, above, the time to sand the primer was comparable for both the inventive 2K method and the comparative 3K method, with both primers sanding in 40 minutes (with two, ten-minute flashes). This is surprising because one cannot expect to store and then use the inventive compositions as a 2 component material.

(46) TABLE-US-00006 TABLE 5 Primer Performance Example 3A (Comparative) Example 3 3K Addition 2K Addition Primer/ Primer/ Primer/ Primer/ Base/ Base/ Base/ Base/ Panel type Primer Primer Clear Clear Primer Primer Clear Clear Film Thickness 72 72 152 163 66 76 171 163 (microns) MEK double rubs 24 h Initial <5 <5 <5 <5 Damage/Mar 24 h 25% Film Loss or >200 >200 200 >200 200 rubs 7 d Initial Damage/Mar 10 10 5 5 7 d 25% Film Loss or >200 >200 >200 >200 200 rubs Cross Hatch Adhesion 24 hour 5B 4B 5B 5B 5B 4B 5B 5B 7 Day 4B 4B 5B 5B 4B 4B 4B 3B

(47) As shown in Table 5, above, the primer prepared in Example 3 (2K addition) had comparable MEK double rubs and cross adhesion results to primers prepared through the 3K addition route, both after 24 h and 7 days. When base and clear coats were applied to the sanded primer, the crosshatch adhesion values of resulting coated panel were comparable between the inventive and comparative examples. This is surprising as the inventive example eliminated the additional separate catalyst component.