3. Limitations:Chemical resistance generally poor.
4. Applications: Used where the properties of ahighquality oil base
paintare required.
8.2.6 Coal TarPlus Epoxy
1. Resistance:E xcellentr esistance to freshwater,s altwater,a nd
inorganic acids.
2. Temperature resistance: 2258 F/108 8 Cd ry; 1508 F/668 Cwet.
3. Limitations:N ot resistant to weather and sunlight; attacked by
organic solvents.
4. Applications: Used on clean blasted steel for immersion service or
belowgrade service.
8.2.7 Urethanes
Polyurethane-resin based coatings arev ersatile. Theya re available as oil
modified, moisture curing, blocked, two component, and lacquers. Properties of the varioust ypes are shown in Table 8.2.
The urethane coatings possess excellent gloss and color retention and
are used as ad ecorative coating of tank cars and steel in highly corrosive
environments. Moisture cured types requireh umidity during application
and may yellowu nderU Vl ight. They have at emperature resistance of
2508 F/1218 Cd ry; 1508 F/ 668 Cw et.
Catalyzed (two component) urethanes exhibitv ery good chemical resistance. They are not recommended for immersion or exposure to strong
TABLE 8.2
Properties of Polyurethane Coatings
One-Component
Property
Urethane
Oil
Moisture
Blocked
TwoComponent
Lacquer
Abrasion resistance Fair–good Excellent
Good–excellent
Excellent
Fair
Hardness
Medium
Medium–hard
Medium–hard
Soft–very hard
Soft–medium
FlexibilityF air–good Good–excellent
Good
Good–excellent
Excellent
Impact resistance
Good
Excellent
Good–excellent
Excellent
Excellent
Solvent resistance
Fair
Poor–fair
Good
Excellent
Poor
Chemical resistance Fair
Fair
Good
Excellent
Fair–good
Corrosion resistance Fair
Fair
Good
Excellent
Good–excellent
Adhesion
Good
Fair–good
Fair
Excellent
Fair–good
Toughness
Good
Excellent
Good
Excellent
Good–excellent
Elongation
Poor
Poor
Poor
Excellent
Excellent
TensileF air
Good
Fair–good
Good–excellent
Excellent
Cure rate
Slow
Slow
FastF ast
None
Cure temperatureR oom
Room
300–3908 F2 128 F/1008 C1 50–2258 F
149–1998 C6 6–1088 C
Specific Organic Coatings
491
CAT8247—CHAPTER 8—17/10/2006—14:20—SRIDHAR—XML MODEL B–pp. 487–507
4. Applications: Used where the properties of ahighquality oil base
paintare required.
8.2.6 Coal TarPlus Epoxy
1. Resistance:E xcellentr esistance to freshwater,s altwater,a nd
inorganic acids.
2. Temperature resistance: 2258 F/108 8 Cd ry; 1508 F/668 Cwet.
3. Limitations:N ot resistant to weather and sunlight; attacked by
organic solvents.
4. Applications: Used on clean blasted steel for immersion service or
belowgrade service.
8.2.7 Urethanes
Polyurethane-resin based coatings arev ersatile. Theya re available as oil
modified, moisture curing, blocked, two component, and lacquers. Properties of the varioust ypes are shown in Table 8.2.
The urethane coatings possess excellent gloss and color retention and
are used as ad ecorative coating of tank cars and steel in highly corrosive
environments. Moisture cured types requireh umidity during application
and may yellowu nderU Vl ight. They have at emperature resistance of
2508 F/1218 Cd ry; 1508 F/ 668 Cw et.
Catalyzed (two component) urethanes exhibitv ery good chemical resistance. They are not recommended for immersion or exposure to strong
TABLE 8.2
Properties of Polyurethane Coatings
One-Component
Property
Urethane
Oil
Moisture
Blocked
TwoComponent
Lacquer
Abrasion resistance Fair–good Excellent
Good–excellent
Excellent
Fair
Hardness
Medium
Medium–hard
Medium–hard
Soft–very hard
Soft–medium
FlexibilityF air–good Good–excellent
Good
Good–excellent
Excellent
Impact resistance
Good
Excellent
Good–excellent
Excellent
Excellent
Solvent resistance
Fair
Poor–fair
Good
Excellent
Poor
Chemical resistance Fair
Fair
Good
Excellent
Fair–good
Corrosion resistance Fair
Fair
Good
Excellent
Good–excellent
Adhesion
Good
Fair–good
Fair
Excellent
Fair–good
Toughness
Good
Excellent
Good
Excellent
Good–excellent
Elongation
Poor
Poor
Poor
Excellent
Excellent
TensileF air
Good
Fair–good
Good–excellent
Excellent
Cure rate
Slow
Slow
FastF ast
None
Cure temperatureR oom
Room
300–3908 F2 128 F/1008 C1 50–2258 F
149–1998 C6 6–1088 C
Specific Organic Coatings
491
CAT8247—CHAPTER 8—17/10/2006—14:20—SRIDHAR—XML MODEL B–pp. 487–507