then combined with pigments and solvents. These paints arepackagedina
single can. The can is opened, the paint mixed and applied. As the solvents
evaporate, the coating becomes hard. Since oxygen in the atmosphere reacts
with the coating to produce additional cross-linking, the final film properties
may be formed weekso rmonths after application.
Among these resin fortified “oil based paints” are included the alkyds,
epoxy esters, oil modifiedurethanes, etc. These paints may be formulated as
air-drying or baking types, and with suitablepigments, can be formulated to
be resistant to avariety of moisture and chemical fume environments as well
as applicationover wood, metal, and masonry substrates.Thesepaints have
the followingadvantages:
Ease of application
Excellent adhesion
Relatively good environmental resistance
Tolerance for poorer surface preparation
Their major disadvantages are:
Cannot be used for immersion or in areas of high chemical fume
concentration
Reduced moisture and chemical resistance compared to other resin
coatings
8.3.1 Epoxy Esters
Esters of epoxies and fatty acids modified.
1. Resistance: Resistant to weathering; limited resistance to chemicals
and solvents.
2. Temperature resistance: 2258 F/108 8 Cd ry; 1508 F/668 Cwet.
3. Limitations:A ttacked by alkalies. Application time between coats
is critical.
4. Applications: Used where the properties of ahigh quality oil based
paintisr equired.
8.3.2 Alkyd Resin
These paints are the mostw idely used synthetic resins. Theya re produced
by reactions of phthalic acid with polyhydric alcoholss ucha sg lycerol and
vegetable oil (or fattyacid). Classificationisbyoil content into drying types
and baking types. Dryingt ypes provide good weathering resistance and
good adhesion to awide variety of substrates, but relatively poor resistance
Specific Organic Coatings
493
CAT8247—CHAPTER 8—17/10/2006—14:20—SRIDHAR—XML MODEL B–pp. 487–507
single can. The can is opened, the paint mixed and applied. As the solvents
evaporate, the coating becomes hard. Since oxygen in the atmosphere reacts
with the coating to produce additional cross-linking, the final film properties
may be formed weekso rmonths after application.
Among these resin fortified “oil based paints” are included the alkyds,
epoxy esters, oil modifiedurethanes, etc. These paints may be formulated as
air-drying or baking types, and with suitablepigments, can be formulated to
be resistant to avariety of moisture and chemical fume environments as well
as applicationover wood, metal, and masonry substrates.Thesepaints have
the followingadvantages:
Ease of application
Excellent adhesion
Relatively good environmental resistance
Tolerance for poorer surface preparation
Their major disadvantages are:
Cannot be used for immersion or in areas of high chemical fume
concentration
Reduced moisture and chemical resistance compared to other resin
coatings
8.3.1 Epoxy Esters
Esters of epoxies and fatty acids modified.
1. Resistance: Resistant to weathering; limited resistance to chemicals
and solvents.
2. Temperature resistance: 2258 F/108 8 Cd ry; 1508 F/668 Cwet.
3. Limitations:A ttacked by alkalies. Application time between coats
is critical.
4. Applications: Used where the properties of ahigh quality oil based
paintisr equired.
8.3.2 Alkyd Resin
These paints are the mostw idely used synthetic resins. Theya re produced
by reactions of phthalic acid with polyhydric alcoholss ucha sg lycerol and
vegetable oil (or fattyacid). Classificationisbyoil content into drying types
and baking types. Dryingt ypes provide good weathering resistance and
good adhesion to awide variety of substrates, but relatively poor resistance
Specific Organic Coatings
493
CAT8247—CHAPTER 8—17/10/2006—14:20—SRIDHAR—XML MODEL B–pp. 487–507