Лако-красочные материалы — производство

Most common and traditional alkyd resins are classified on the basis of their oil content (wt% of oil in final resin) as:

• Short oil alkyd resin: oil content <40 %

• Medium oil alkyd resin: oil content 40 to 60 %

• Long oil alkyd resin: oil content 60 to 70 %

• Very long oil alkyd resin: oil content 70 to 85 %.

Long oil alkyd resins have been the workhorse as binders for architectural and do-it-yourself paints, anticorrosive coatings (lin­seed oil based), metal primers and intermediate coats. They are mainly based on such oils as soybean oil, linseed oil, dehydrated castor oil and safflower oil.

Medium oil alkyd resins are based on drying oils or fatty acid mixtures, and are useful as binders for architectural coatings and industrial coatings, including cost-effective auto refinishes, metal primers, and original equipment manufacturing (OEM) finishes for air-drying as well as force-drying applications. Due to their compatibility, they are frequently used in combination with such other film formers as nitrocellulose to improve drying, other hard resins to increase hardness and gloss, chlorinated rubber for impro­ved chemical resistance and amino resins for heat cured (stoving) finishes.

Short oil alkyd resins can produce harder and more durable films in combination with amino resins for industrial stoving finishes, such as for appliances and OEM applications. Most such resins for stoving finishes are based on non-drying oils and have improved yellowing resistance. Short oil resins are also formulated with urea or melamine resins for two-component wood coatings (frequently known as catalyzed lacquers), in which the second component is a solution of acid catalyst (such as p-toluene sulfonic acid) in alcohol. They are also combined with nitrocellulose as plasticizing resins for inexpensive furniture lacquers and automotive refinishing sys­tems. Chain-stop alkyd resins, based on linoleic-rich fatty acids, are also an example of short oil alkyd resins mainly used in OEM applications requiring fast-drying coatings (1/2 to 2 h). Shorter oil length generally results in a need for aromatic solvents.