Two-component High-Solid polyurethane coating systems based on soy polyols.

Soybean oil based polyols--soybean oil phosphate ester polyols (SOPEPs)--having varying hydroxyl content and viscosity were prepared as low cost and low-VOC polyols for coatings applications. These SOPEPs were used as the hydroxyl component of "two-component polyurethane (2K-PU)" coating compositions and their film properties were studied. Blends of commercial polyester polyol and SOPEP in varying proportions were also used to formulate PU coatings. Their film properties were studied and compared. We found that SOPEP can be used as the sole hydroxyl component or as the reactive diluent for polyester polyols in 2K-PU coating systems. SOPEP is derived from a relatively inexpensive and renewable resource and the use of SOPEP can substantially reduce VOC and cost of PU coating formulations.

Keywords: Hardness, scratch resistance, prohesion elongation, polyurethanes, soy polyol hyperbranched, solvent-based, urethane, VOC

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Polyurethanes (PU) have found extensive applications in the coatings industry mainly because they exhibit excellent abrasion resistance, toughness, low temperature flexibility, chemical and corrosion resistance, and a wide range of mechanical strength. Because of these characteristics, PU coatings have emerged as coatings of choice for applications from industrial maintenance to automobile finishing to chemical resistant coatings. (1-2) Two-component polyurethane (2K-PU) systems are especially attractive since they offer flexibility in formulation, which enables one to customize according to demanding enduse requirements. Polyols are major components of PU coating systems and are often designed to suit the performance requirements of the intended applications. Among the common commercially available polyols for 2K-PU systems are hydroxyl-functional polyesters, hydroxyl-functional acrylics, and polyether polyols. Polyesters and acrylics produce very tough polyurethane films under proper curing conditions and are among the most widely used polyols for high performance coatings. Polyether polyols are generally used in highly flexible systems such as sealants and other noncoating applications.

In recent years, there has been renewed interest in developing materials and products based on bio-based and renewable resources. The principal drivers for this, among others, include environmental, regulatory, and economic factors. A recent study indicates that soy-based polyols equal about 25% of the total environmental impact of the petroleum-based polyols and that the use of soy polyols will result in significant reductions in global warming, smog formation, ecological toxicity, and fossil fuel depletion. (3) Preparation of polyols from vegetable oils has been extensively reported in the literature. (4-13) A variety of chemical modifications to vegetable oils have been studied to derive multiple hydroxyl-functional derivatives. Guo et al. (14) reported preparation of soy polyols by the hydrogenation of hydroformulated soybean oil and studied the physical and mechanical properties of polyurethanes based on these soy polyols.

Petrovic et al. (15) prepared a series of polyurethanes from halogenated, hydrogenated, and methoxylated epoxidized soybean oil with an average OH functionality of 3.7. Polyurethanes based on nonhalogenated soy polyols showed higher thermal stability but lower glass transition and mechanical properties. Guo et al. (16) reported that PU foams based on polypropylene oxide polyols and those based on soy polyols have comparable mechanical and thermoinsulating properties, that the soy polyol foams were more stable toward both thermal degradation and thermal oxidation. The lack of ether linkages in the soy-based polyols is thought to be the origin of improved thermal and thermo-oxidative stabilities of soy-based PU foam. Petrovic and Javni (17) reported the use of soy polyols with PU prepolymers made from epoxidized soybean oil and polymeric 4,4'-diphenylmethane diisocyanate to make coatings with good adhesion and hardness. Gerbase et al. (18-19) studied and reported different methods to functionalize vegetable oils in order to derive bio-renewable materials.

Our research group has primarily focused on epoxidized vegetable oils for deriving soy polyols using phosphoric acid as a modifying agent. Synthesis of soybean oil phosphate ester polyol from epoxidized and partially epoxidized soybean oil (ESBO) has been previously reported. (20-21) The processes were developed to control oligomer formation and minimize hydrolysis of the glyceryl ester bonds in ESBO. Soybean oil phosphate ester polyols (SOPEP) from ESBO with various epoxy values have been made and formulated in coatings. The film properties of the baking compositions based on these polyols were studied for both solventborne and waterborne systems. (22) Low cost systems with good physical properties and excellent adhesion were reported.

In the present study, we derived soy polyols containing phosphate ester groups with varying OH contents from epoxidized soybean using phosphoric acid as both catalyst and modifying agent. In the present work, a series of SOPEPs with hydroxyl contents varying from 3.6% to 7.3% were synthesized from epoxidized soybean oil. The film properties of 2K-PU coatings systems containing these polyols were studied.

MATERIALS

Partially epoxidized soybean oil (3.5% oxirane oxygen) and fully epoxidized soybean oil (7.0% oxirane oxygen) were supplied by Atofina Chemicals Inc. Aromatic isocyanate prepolymer Desmodur[TM] E744 (diphenylene-4,4'-diisocyanate(MDI)-based) and aliphatic polyisocyanate Desmodur[TM] Z4470 BA (isophoronedisocyanate(IPDI)-based) were provided by Bayer Corporation. The properties of isocyanate compounds are shown in Table 1. Polyester polyol Desmophen[TM] 651A-65 was procured from Bayer (%OH content -- 5.2, NVM by wt. -- 65%, acid number -- 3.0). Tertiary butyl acetate, TBAc[TM], was provided by Lyondell Chemical Company. Dibutyltindilaurate, xylene, super phosphoric acid, isopropyl alcohol, and methylethylketone (MEK) used in the study are analytical grade chemicals (Aldrich) and were used as received. The test panels (6 in. x 4 in. x 0.032 in.) used for the study of film properties were standard low carbon, cold rolled steel (dull matte finish), complying with ASTM A366, supplied by Q-Panel Lab Products.

SYNTHESIS OF SOYBEAN OIL PHOSPHATE ESTER POLYOLS

All the reactions were carried out in either a 250 ml or 500 ml four-necked flask equipped with a variable speed stirrer, a thermometer, an inert gas inlet tube, a condenser, and a dropping funnel. Flasks were heated with electric heating mantles connected to a variable voltage transformer. A general method for the synthesis of SOPEPs is described below.

ESBO (150.0 g) and 2-propyl alcohol (75% to 90% based on weight of ESBO) were charged into a 500-ml reaction flask under agitation. Super phosphoric acid (from 2% to 4% based on weight of ESBO) dissolved in distilled water (15.0 g) was added to the flask from a dropping funnel at controlled rates of addition (30-45 min). Temperature during addition of phosphoric acid solution varied from 50[degrees]C-100[degrees]C for different samples. After addition was complete, the reaction mixture was stirred at 70[degrees]C-80[degrees]C until the residual oxirane content reached the desired endpoint. Progress of the reaction was monitored by testing a sample for percent oxirane content at regular intervals, by chemical method. (23) Heating was stopped when the percent oxirane oxygen content reached less than 0.2%. The unreacted water and solvent were then distilled off under a rotary vacuum evaporator. The characteristics of the SOPEPs thus prepared are presented in Table 2. SOPEP I, III, and IV were synthesized from fully epoxidized soybean oil (7.0% oxirane oxygen) using 1%, 2%, and 4% phosphoric acid. SOPEP II was prepared from partially epoxidized (3.5% oxirane oxygen) using 2% phosphoric acid.

CHARACTERIZATION OF SOPEP

SOPEP samples were characterized for acid value (ASTM D 1639), hydroxyl value (ASTM D 1957), percent oxirane oxygen content (ASTM 1652-73, Method-1), viscosity (ICI cone and plate viscometer), and percent volatile content. Table 2 shows the characteristics of the different samples of SOPEP prepared and used in this study.

COATING COMPOSITIONS

Two-component polyurethane coating compositions formulated and studied from different SOPEPs are shown in Table 3. Compositions Ar-I to Ar-IV are based on aromatic polyisocyanate, whereas Al-I to Al-IV are based on aliphatic polyisocyanate

We chose to use isophorone diisocyanate (IPDI)-based aliphatic polyisocyanate since our initial study indicated very slow reactivity of hydroxyl groups of SOPEP with polyisocyanates based on hexamethylenediisocyanate (HDI). IPDI-based polyisocyanates are known to give harder films and faster drying as compared to HDI-based polyisocyanates. (24) These polyisocyanates are, therefore, generally recommended for their use with alkyd types of resins (flexible co-reactants). Due to structural similarities of alkyds with SOPEP, an IPDI-based polyisocyanate was chosen. Two-component polyurethane coating compositions were also prepared by using a blend of commercial polyester polyol and SOPEP IV in varying proportion, to study the effect on film properties. These compositions are shown in Table 4. SOPEP IV was selected for this study because its hydroxyl content was comparable to that of the commercial polyol. The polyester/SOPEP IV blend was employed as a hydroxyl component with both aromatic (PS-25-Ar to PS-100-Ar) and aliphatic polyisocyanate (PS-25-Al to PS-100-Al). All the coatings were formulated having an isocyanate index of 1.10.

All the compositions were formulated to have viscosities between 2.0 to 3.0 poise at 25[degrees]C, to enable comparison of their nonvolatile content and VOC at application viscosity. Dibutyltindilaurate was used as catalyst for the curing reaction.

[FIGURE 1 OMITTED]

APPLICATION AND TESTING OF FILM PROPERTIES

The hydroxyl component and isocyanate components were thoroughly mixed just before the application of their films onto the steel panels. Films were applied with varying wet film thickness, such that the dried films of all the compositions had a thickness of approximately 1.0 mil. The films were allowed to cure at ambient conditions (25[degrees]C and relative humidity of approximately 45%) for at least 168 hr before tests for mechanical and chemical properties were carried out.

Compositions were tested for their pot-life by checking for the rise in their viscosity after mixing the two components at an interval of 30 min until their Gardner-Holdt viscosity was greater than T (approximately double the initial value) at ambient temperature. Films were tested for drying time (ASTM D 5895), pencil hardness (ASTM D 3363-92a), cross-hatch adhesion (ASTM D 4752), solvent resistance (ASTM D 5402), and impact resistance (ASTM D 2794-92). Chemical resistance of the films was studied by the "spot-test" for 30 min.

The extent of cure of two-component polyurethane coating systems formulated with polyester polyol (conventional) and SOPEP with aliphatic IPDI-based polyisocyanate was compared under ambient and elevated temperature conditions using FTIR spectroscopy. The two sets of coatings were applied onto the potassium bromide pellets and their FTIR spectra were recorded (designated as 0-hr spectra). One of the pellets was then put in an oven maintained at 80[degrees]C for one hour. The pellet was cooled in a desiccator and the spectrum was recorded (designated as heat-cured sample). The second pellet was exposed to the ambient environment (approx 30[degrees]C and 40% RH) and the spectrum was recorded at regular intervals (eight hours). The final spectrum was recorded after seven days of curing (designated as seven-day sample). Primarily, the isocyanate peaks in the spectrum were observed.

RESULTS AND DISCUSSION

Synthesis of SOPEPs

The characteristics of SOPEPs prepared for the study are presented in Table 2. The results show that it is possible to prepare SOPEPs that vary in hydroxyl content and viscosity by varying the amount of phosphoric acid. The values for hydroxyl contents are lower when compared to the calculated values (based on each epoxide group upon hydrolysis producing two hydroxyl groups).

The acid catalyzed reaction of ESBO with water is believed to follow the reaction scheme shown in Figure 1. Under the experimental conditions used, there appears to be two competing reactions taking place simultaneously. The hydrolysis reaction, by nucleophilic attack of water on the carbon atom of the epoxide group, produces a hydroxyl on the fatty acid backbone. The other competing reaction is oligomerization by an epoxy-epoxy or hydroxy-epoxy reaction with formation of an ether linkage. Soucek et al. conducted extensive research in this area and proposed a mechanism for oligomerization of cycloaliphatic epoxide compounds. (25-26) Due to the structural similarity of ESBO with cycloaliphatic epoxide, we believe that a similar reaction mechanism is probable. The lower viscosity of SOPEP IV (prepared with 4% phosphoric acid) was believed to be due to a higher degree of hydrolysis and lower degree of oligomerization, resulting in lower average molecular weight. Lower viscosity and lower hydroxyl content for SOPEP II could be attributed to a lower degree of oligomerization due to lower epoxy content (3.5% oxirane oxygen) of the ESBO.

It is difficult in a neat system to effect complete hydrolysis of epoxide groups before any appreciable oligomerization. Higher degrees of hydrolysis result in a product with higher hydroxyl content and lower viscosity, whereas etherification (oligomerization) results in lower hydroxyl content and higher viscosity. The process and the reagents used in the synthesis of SOPEP makes them low cost polyols.

FILM PROPERTIES

SOPEP-Based Compositions

Table 5 shows ambient temperature cured film properties of PU coatings based on straight SOPEPs. For both aromatic and aliphatic systems, drying characteristics and film hardness improved as hydroxyl content of the polyol was increased. This can be attributed to increasing crosslink density of the film matrix. Physical properties of aliphatic systems are inferior to the aromatic systems. This could be due to incomplete cure of IPDI. (22) Polyisocyanates based on IPDI have higher [T.sub.g], which leads to faster setting of film, resulting in incomplete cure.

Comparison of impact resistance indicated that films of aromatic systems were significantly tougher than their aliphatic counterparts. Within the aliphatic series, impact resistance was found to improve with increasing hydroxyl content.

Results of the MEK double rub tests indicated that, in general, PU films based on SOPEP did not have good resistance to polar solvent. That this poor solvent resistance might be due to the higher concentration of softer segments (SOPEP) in the film matrix was investigated with FTIR. The FTIR spectra for both of the 2K-PU systems, cured under different conditions, are shown in Figures 2-5. Based on these spectra, the following was concluded:

(1) Seven-day ambient cure is equivalent to curing at 80[degrees]C for one hour.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

(2) Polyester polyol formulations show a significantly lower degree of reaction, both at ambient and at elevated temperature, as indicated from isocyanate peak at 2258 m (Figures 4 and 5). This might be due to the expected higher [T.sub.g] of polyester systems leading to "vitrification" of the film resulting in reduced mobility and reactivity of residual isocyanate and hydroxyl groups.

(3) Formulations based on SOPEP show a significantly higher degree of reaction at both ambient and elevated temperature curing conditions (Figures 2 and 3). This can be attributed to the greater free volume of the hyperbranched polyol structure enabling sufficient mobility of functional groups to react to a significantly higher degree compared to that for polyester polyol.

Based on the above, we believe that the poor solvent resistance (low MEK double rubs) was primarily a result of the SOPEP fatty acid chains rather than insufficient degree of curing.

We also observed similar results, in a separate study, for coatings based on SOPEP cured with melamine type crosslinker at elevated temperature. While all films were found to be resistant to acids and alkali, they were sensitive to polar solvent MEK, but fairly resistant to xylene.

VOC and Solid Content

The calculated VOC and nonvolatile content of all the compositions studied are reported in Tables 3 and 4. Tertiary butyl acetate is a VOC exempt solvent. The study indicated that it is possible to formulate compositions having substantially lower VOC and higher solids due to low viscosities of SOPEP, compared to polyester polyols. SOPEP had good solubility in tertiary butyl acetate, which allows for the incorporation of this solvent in very low VOC formulations.

Polyester/SOPEP-Based Compositions

Results of the film properties of polyester/SOPEP blend systems are presented in Table 6. Incorporation of SOPEP into polyester polyol would be expected to reduce the film hardness and solvent resistance (MEK) of the cured film, for both aromatic and aliphatic systems. However, it was evident that incorporation of SOPEP at the 25% level did not significantly affect most film properties when compared with straight polyester-based films. It therefore follows that SOPEP, having a hydroxyl content comparable to that of polyester polyol, can be incorporated in up to 25% of polyester polyol without any significant loss of properties. This can result in substantial reduction in cost and VOC with increased nonvolatile content at application viscosity.

CONCLUSION

Soy-based polyols with varying hydroxyl content and viscosity can be synthesized from epoxidized soybean oil. SOPEPs can be employed as a hydroxyl component of a 2K-PU coating system with distinct advantages of low cost and lower VOC. Generally, hardness and solvent resistance are reduced by SOPEP systems, as compared to conventional polyester polyol-based systems. However, SOPEP, having higher hydroxyl content, can be used as a reactive diluent for polyester polyols up to 25%, without any appreciable compromise in film properties. This can result in substantial reduction in VOC and the costs of the coating systems.

ACKNOWLEDGMENT

The authors wish to thank the United Soybean Board for its financial support of this research. The authors are also thankful to Ravi Joshi, Eastern Michigan University, for assistance with FTIR spectroscopy.

References

(1) Wicks, Z.W., Jones, F.N., and Pappas, S.P., Organic Coatings Science and Technology, 2nd Ed., p. 180, Wiley Interscience, 1999.

(2) Stoy, D. and Freitag, W. (Eds.), Resins for Coatings--Chemistry, Properties and Applications, pp. 177-221, Hanser Publishers, 1996.

(3) Pollock, J.W., "Soy vs. Petro Polyols: A Life Cycle Comparison," Abstracts of Papers, 227th ACS National Meeting, Anaheim, CA, March 28-April 1, 2004.

(4) Guo, A., Javni, I., and Petrovic, Z., J. Appl. Polym. Sci., 77, 467-473 (2000).

(5) Petrovic, Z.S., Guo, A., Javni, I., and Zhang, W., Proc. Polyurethanes EXPO 2000, API, Boston, MA, 2000.

(6) Petrovic, Z.S., Javni, I., and Guo, A., Proc. Polyurethanes EXPO '98, SPI, Polyurethane Division, Dallas, TX, pp. 559-562, 1998.

(7) Gruber, B., Hoefer, R., Kluth, H., and Meffert, A., Fett Wissenschaft Technologie--Fat Science Technology, 89, 147-151, 1987.

(8) Hofer, R., Daute, P., Grutzmacher, R., and Westfechtel, A., "Oleochemical Polyols--A New Raw Material Source for Polyurethane Coatings and Floorings," J. COAT. TECHNOL., 69, No. 869, 65 (1997).

(9) Khoe, T.H., Otey, F.H., and Frankel, E.N., J. Am. Oil Chem. Soc., 49, 615-618 (1972).

(10) Lyon, C.K., Garrett, V.H., and Frankel, E.N., J. Am. Oil Chem. Soc., 51, 331-334 (1974).

(11) Bilyk, A., Monroe, H.A. Jr., Saggese, E.J., and Wrigley, A.N., J. Am. Oil Chem. Soc., 51, 119-122 (1974).

(12) Saggese, E.J., Zubillaga, M., Bilyk, A., Riser, G.R., and Wrigley, A. N., J. Am. Oil Chem. Soc., 51, 123-125 (1974).

(13) Scholnick, F., Saggese, E.J., Wrigley, A.N., and Riser, G.R., J. Am. Oil Chem. Soc., 47, 180-182 (1970).

(14) Guo, A., Cho, Y.J., and Petrovic, Z.S., "Nonhalogenated Soy-Based Polyols," J. Polym. Sci. Part A: Polym. Chem., 38, 3900-3910 (2000).

(15) Petrovic, Z.S., Guo, A., and Zhang, W., "Structure and Properties of Polyurethanes Based on Halogenated and Nonhalogenated Soy-Polyols," J. Polym. Sci. Part A: Polym. Chem., 38, 4062-4069, 285 (2000).

(16) Javni, I., Petrovic, Z.S., Guo, A., Fuller, R., "Thermal Stability of Polyurethanes Based on Vegetable Oils," J. Appl. Polym. Sci., 77(8), 1723-1734 (2000).

(17) Petrovic, Z.S. and Javni, I.J., "Preparation of Epoxidized Natural Oil-Based Isocyanate Prepolymers for Preparing," U.S. Patent 6,399,698 B1, 2002.

(18) Gerbase, A.E., Gregorio, J.R., Martinelli, M., Brasil, M.C., and Mendes, A.N.F., "On the Epoxidation of Soybean Oil by the Methyltrioxorhenium-C[H.sub.2][Cl.sub.2]/[H.sub.2][O.sub.2] Catalytic Biphasic System," J. Am. Oil Chem. Soc., 79, 179-181 (2002).

(19) Gerbase, A.E., Gregorio, J.R., Martinelli, M., Brasil, M.C., and Mendes, A.N.F., "Reactivity of the Biphasic Trichloroacetonitrile-C[H.sub.2][Cl.sub.2]/[H.sub.2][O.sub.2] System in the Epoxidation of Soybean Oil," Grasas y Aceites, 53, 175, 300 (2002).

(20) Kuang, Z., Qiu, X., Bai, X., Shaw, C., Sarnecki, G., Baghdachi, J., and Massingill, J.L., "High Solids Alkyd Coatings Using Reactive Diluents," Proc. 26th International Waterborne, High-Solids, and Powder Coatings Symposium, New Orleans, LA, pp. 126-141, 1999.

(21) Mannari, V., Gandhi, V., and Massingill, J. Jr., "Soy-Based Phosphated Polyols for Coatings Applications," 95th AOCS Annual Meeting and Expo, May 9-12, Cincinnati, OH, 2004.

(22) Zhong, B., Shah, C., Rahim, M., and Massingill, J., "Novel Coatings From Soybean Oil Phosphate Ester Polyol," J. COAT. TECHNOL., 73, No. 915, 53 (2001).

(23) "97 Standard Test Methods for Epoxy Content of Epoxy Resins," ASTM International, West Conshohocken, PA.

(24) Stoy, D. and Freitag, W. (Eds.), Resins for Coatings--Chemistry, Properties and Applications, Hanser Publishers, pp. 188-189, 1996.

(25) Wu, S. and Soucek, M.D. "Kinetic Modelling of Crosslinking Reactions for Cycloaliphatic Epoxides with Hydroxyl- and Carboxyl-Functionalized Acrylic Copolymers: I- pH and Temperature Effects," Polymer, 39 (23), 5747 (1998).

(26) Wu, S. and Soucek, M.D. "Oligomerization Mechanism of Cyclohexene Oxide," Polymer, 39 (15), 3583 (1998).

Vijay M. Mannari -- Eastern Michigan University*

John L. Massingill, Jr.** -- Texas State University ([dagger])

Presented at the International Waterborne, High-Solids, and Powder Coatings Symposium, New Orleans, LA, February 2002.

* Coatings Research Institute, Ypsilanti, MI 48197.

([dagger]) Center for Coatings and Bio-Based Technology, Institute for Environmental and Industrial Science, 340 Centennial Hall, San Marcos, TX 78666.

** Author to whom correspondence should be addressed.

Table 1 -- Properties of the Isocyanate Components Used for the Coatings

Properties             Desmodur Z4470 BA     Desmodur E744

Chemistry              IPDI-based aliphatic  MDI-based aromatic
                         polyisocyanate        polyisocyanate
Appearance             Clear, slightly       Clear, brownish
                         yellow liquid         yellow liquid
NCO content (%)         11.9                  23.2
Viscosity @            600                   360
  25[degrees]C (mPaS)
Solids (%)              70.0                 100.0
Equivalent weight      353                   179
  (as supplied)
Specific gravity @       1.05                  1.2
  25[degrees]C
  (g/[cm.sup.3])

Table 2 -- Properties of SOPEP Samples

Characteristics                  SOPEP I  SOPEP II  SOPEP III  SOPEP IV

Viscosity @ 70[degrees] (poise)   22.70     9.00     27.00      12.90
Specific gravity                   1.010    0.997     1.006      1.001
% Volatile matter (by wt.)         0.05     0.10      0.20       0.20
Hydroxyl content %                 4.36     4.70      5.45       7.64
Hydroxyl equivalent weight (g)   389.9    361.7     311.9      222.5
Acid value (mg of KOH)             1.75    14.70     12.00       9.20

Table 3 -- PU Coating Compositions Based on SOPEP

                               Compositions (wt%)
Components                Ar-I    Ar-II   Ar-III  Ar-IV

SOPEP I                    49.70
SOPEP II                           48.55
SOPEP III                                  45.80
SOPEP IV                                           39.90
Aromatic polyisocyanate    25.11   26.30   29.00   34.92
Aliphatic polyisocyanate
Tert butyl acetate         25.04   25.00   25.05   25.03
DBTL                        0.15    0.15    0.15    0.15
Total                     100.00  100.00  100.00  100.00

% NVM                      75.00   74.95   74.97   68.01
Specific gravity            1.01    1.01    1.01    1.02
Volume solids              70.84   71.01   70.70   70.48
VOC (wt%)                  25.04   25.00   25.05   25.03
VOC (g/L)                   0.00    0.00    0.00    0.00

                               Compositions (wt%)
Components                Al-1    Al-2    Al-3    Al-4

SOPEP I                    39.70
SOPEP II                           41.40
SOPEP III                                  35.45
SOPEP IV                                           32.30
Aromatic polyisocyanate
Aliphatic polyisocyanate   40.15   44.86   45.05   56.70
Tert butyl acetate         19.95   13.54   19.30   10.80
DBTL                        0.20    0.20    0.20    0.20
Total                     100.00  100.00  100.00  100.00

% NVM                      73.00   67.19   72.19
Specific gravity            1.00    1.00    1.00    1.02
Volume solids              63.99   69.60   63.07   68.49
VOC (wt%)                  32.00   27.00   32.82   27.81
VOC (g/L)                 119.98  135.04  134.88  172.84

Table 4 -- PU Coating Compositions Based on Polyester/SOPEP Blends

                                    Compositions (wt%)
Components                PS-25-Ar  PS-50-Ar  PS-75-Ar  PS-100-Ar

Polyester polyol (70%)     13.85     25.55     34.80     40.15
SOPEP IV                   26.95     16.60      7.60
Aromatic polyisocyanate    31.90     29.75     27.30     24.00
Aliphatic polyisocyanate
Tert butyl acetate         27.20     28.00     30.22     35.77
Xylene
DBTL                        0.10      0.10      0.08      0.08
Total                     100.00    100.00    100.00    100.00

% NVM                      67.95     63.06     57.60     50.18
Specific gravity            1.03      1.03      1.03      1.02
Volume solids              62.39     56.62     50.30     42.14
VOC (wt%)                  32.05     36.94     42.40     49.82
VOC (g/L w/o TBAc)         49.75     92.31    125.84    143.80

                                    Compositions (wt%)
Components                PS-25-Al  PS-50-Al  PS-75-Al  PS-100-Al

Polyester polyol (70%)     10.30     19.05     26.00     30.18
SOPEP IV                   20.00     12.45      5.72
Aromatic polyisocyanate
Aliphatic polyisocyanate   47.50     44.50     41.50     36.15
Tert butyl acetate         22.08     23.88     23.68     23.58
Xylene                                          3.00     10.00
DBTL                        0.12      0.12      0.10      0.09
Total                     100.00    100.00    100.00    100.00

% NVM                      60.07     56.10     51.77     45.01
Specific gravity            1.00      1.01      1.01      1.00
Volume solids              54.96     50.35     45.42     38.19
VOC (wt%)                  39.94     43.90     48.23     54.99
VOC (g/L w/o TBAc)        178.98    201.36    247.06    313.07

Table 5 -- Film Properties of PU Coatings Based on SOPEP

Compositions                      Ar-I     Ar-II    Ar-III   Ar-IV

Pot-life (hr)                      9.0      9.0      6.0      5.0

Drying time (min)
  Surface drying                  30       30       20       20
  Tack-free                       90       70       70       60

Pencil Hardness
  Gouge                           2H       H        3H       4H
  Scratch                         HB       HB       H        H

Impact Resistance (D/R) (lb/in)  160/160  160/160  160/160  160/160
Adhesion                          4B       5B       4B       4B
% Elongation                     >32%     >32%     >32%     >32%
MEK double-rubs (passes)          25       25       25       50

Chemical Resistance (a)
Spot-Test (30 min)
  Xylene                           0        0        0        0
  MEK                              5        5        4        1
  10% HCL                          0        0        0        0
  10% Acetic acid                  0        0        0        0
  10% NaOH                         0        0        0        0

Compositions                     Al-I   Al-II    Al-III  Al-IV

Pot-life (hr)                    12.0   12.0      9.0      7.0

Drying time (min)
  Surface drying                  60     45       45      40
  Tack-free                      150    120      120      90

Pencil Hardness
  Gouge                          H      F        H        H
  Scratch                        HB     HB       HB       HB

Impact Resistance (D/R) (lb/in)  60/50  160/160  80/60   120/100
Adhesion                         2B     5B       5B       5B
% Elongation                     >32%   >32%     >32%    >32%
MEK double-rubs (passes)         <25     25       25      25

Chemical Resistance (a)
Spot-Test (30 min)
  Xylene                           3      2        0       0
  MEK                              5      3        2       2
  10% HCL                          0      0        0       0
  10% Acetic acid                  0      0        0       0
  10% NaOH                         0      0        0       0

(a) 0 -- No marks, 1 -- very slight marks, 2 -- slight marks,
3 -- prominent marks, 4 -- partial film detachment, 5 -- complete film
detachment.

Table 6 -- Film Properties of PU Coatings Based on SOPEP/Polyester
Blends

                                                                PS-100-
Compositions                      PS-25-Ar  PS-50-Ar  PS-75-Ar  Ar

Pot-life (hr)                       5.0       4.5       4.5        4.5

Drying time
  Surface drying                   20        20        15         15
  Tack-free                        50        50        45         45

Pencil Hardness
  Gauge                           3H        4H        5H         5H
  Scratch                         H         2H        3H         3H

Impact Resistance (D/R) (lb/in.)  160/160   160/160   160/160    160/160
Adhesion                          4B        5B        5B         5B
% Elongation                      >32%      >32%      >32%       >32%
MEK double rubs (passes)           25        75       200       >200

Chemical Resistance (a)
Spot-Test (30 min)
  Xylene                            0         0         0          0
  MEK                               2         2         2          1
  10% HCL                           0         0         0          0
  10% Acetic acid                   0         0         0          0
  10% NaOH                          0         0         0          0

                                                                PS-100-
Compositions                      PS-25-Al  PS-50-Al  PS-75-Al  Al

Pot-life (hr)                       7.0       7.0       6.5        6.0

Drying time
  Surface drying                   35        30        30         25
  Tack-free                        90        80        70         70

Pencil Hardness
  Gauge                           H         2H        2H         3H
  Scratch                         F         F         H          H

Impact Resistance (D/R) (lb/in.)  130/100   140/120   160/160    160/160
Adhesion                          5B        5B        5B         5B
% Elongation                      >32%      >32%      >32%       >32%
MEK double rubs (passes)           25        75       200       >200

Chemical Resistance (a)
Spot-Test (30 min)
  Xylene                            2         2         1          0
  MEK                               5         4         0          2
  10% HCL                           0         0         0          0
  10% Acetic acid                   0         0         0          0
  10% NaOH                          0         0         0          0

(a) 0 -- No marks, 1 -- very slight marks, 2 -- slight marks,
3 -- prominent marks, 4 -- partial film detachment, 5 -- complete film
detachment.