Glyptal resins used in paints and lacquers are chemically which type of polymer?

Introduction / Context:
“Glyptal” historically refers to polyesters produced from glycerol and phthalic anhydride, widely used as binders in coatings and electrical varnishes. Knowing the polymer type clarifies curing behavior and solvent resistance.

Given Data / Assumptions:

• Monomers: glycerol (triol) and phthalic anhydride (dicarboxylic acid anhydride).
• Application: paints, varnishes, lacquers.

Concept / Approach:
Condensation of polyols with dibasic acids yields polyester chains. These can be further modified or crosslinked (e.g., with drying oils) for film formation. The backbone contains ester linkages, distinguishing it from amide, styrenic, or nitrile polymers.

Step-by-Step Solution:
Identify monomer functionality (triol + diacid anhydride).Condensation gives ester linkages → polyester.Therefore, choose “Polyester.”

Verification / Alternative check:
Coating literature classifies glyptal/alkyds within the polyester family, with oil length determining flexibility and drying behavior.

Why Other Options Are Wrong:
Polyamide: requires amide linkages (nylons).Polystyrene and polyacrylonitrile: chain-growth vinyl polymers; different chemistry and uses.Phenolic: phenol–formaldehyde networks, not glyptal.

Common Pitfalls:
Equating alkyds with “acrylics” due to coating context; confusing brand names with polymer families.

Final Answer:
Polyester