Лако-красочные материалы — производство

Automotive Finishes OEM & VR
by Kevin O’Hara LRSC

Plastic Coatings
by Chris Langham LTSC

Interior and Exterior Masonry
by Ian Royston BSc

Concrete Coatings
by Roy Usher BSc

Coatings for Metal by
Ian Royston BSc and Roy Usher BSc

Maintenance Coating
by Roy Usher BSc

Marine and Offshore Coatings
by Ian Royston BSc

Edited by Peter Lam PhD BSc and Peter Oldring PhD BA

Chapter Three

I INTRODUCTION

Thermoplastic solution acrylic resins were the first type of acrylics to be commercialised in the 1930’s, for speciality uses. In the 1950’s they began to be used for automotive applications, in the United States, replacing nitrocellulose based finishes and synthetic enamels. They offered significantly improved colour, colour stability and exterior durability over other polymers of similar cost. Thermoplastic acrylics are prepared by the homo/copolymerisation of acrylic monomers and are usually regarded as inert. Today two main classes of thermoplastic acrylics are commercially available:

a) Supplied as a solution in an organic solvent.

b) Supplied as solid beads or granules.

The former type is produced by solution polymerisation, the second by using solution, bulk and suspension polymerisation techniques.

Whilst the products already supplied in solution may be more convenient for the paint or ink manufacturer to use, bead acrylic copolymers are much more versatile, offering a wider selection, and often superior film properties. Solid bead acrylics allow the paint or ink formulator much greater freedom in the choice of solvents to suit a particular application. Since solid acrylics are normally supplied as free flowing granules, the formulator can dissolve the resin in solvent relatively simply, using a high speed Cowles type stirrer or dissolver. However, because many thermoplastic resins are of a reasonably high molecular weight, the resulting solution is either of high viscosity or low solids. The major characteristics of thermoplastic acrylics which govern their use in specific applications are:

• Colour (water white)

• Colour stability

• Chemical & water resistance

• Rapid drying

• Adhesion

• Bum without ash

• Exterior durability

It should be noted that some of the above properties are affected more by changing the composition than others, particularly exterior durability.