Лако-красочные материалы — производство

Emulsion polymers are unique in many of the test methods required to characterise the system. Some of the tests specific to latices will be outlined here. (i) Freeze Thaw Stability Latices containing up to 50% water are susceptible to freezing. Upon thawing it is possible for destabilisation of the latex to occur. The normal test […]

Emulsions resulting from the emulsion polymerisation of acrylic or vinyl monomers are unique compared to other resins used for surface coating applications. As such they have properties which are totally different to a conventional solution acrylic, polyester or alkyd resins. Their mechanism of film formation is totally different to other types of resins. Because particles […]

Control of molecular weight is more difficult with acrylic resins than with alkyd or polyester resins, especially in terms of achieving low polymer molecular weight with good film performance. This exacerbates the problems encountered with viscosity control in water reducible systems, caused by the hydrogen bonding setup between the polymer, solvent, and water in the […]

Since conventional low temperature acrylic reactors are unable to maintain the temperatures required to boil many of the glycol ethers used as solvents in water reducible systems, process temperatures cannot be controlled by refluxing boiling solvents. This puts greater emphasis on good process control procedures to achieve reproducible polymer manufacture.

The principles of amine and cosolvent selection apply broadly across all types of polymer. However, the specific details of the apparent ‘solvent strength’ of an amine and optimum choice of cosolvent will vary to some extent from one polymer type to another, and will often be influenced by the application method and conditions of cure. […]

The solvents used in water reducible coatings are usually polar and are fully or partially water miscible. These are alcohols and glycol ethers. Those based on ethylene glycol have been the most commonly used, but are now being superseded by propylene glycol based glycol ethers because of their reduced toxicity. Different levels and types of […]

Since the overwhelming majority of commercially available water reducible polymers are carboxyl functional, the discussion in this chapter will consider the use of amines. However, the calculations used to determine the quantities of neutralising agent required by a given polymer can be used with modification for acid neutralised systems. The choice of amine used to […]

True water soluble polymers as previously discussed, are usually those having repeating polar groups in the polymer chain, and are water soluble in their own right, typical groups being hydroxyl, ether, carbonyl, amide, etc. Water reducible, or water thinnable, synthetic polymers are usually acidic, typically containing carboxyl groups built into the polymer chain. These require […]

Water soluble resins will not be considered further. Two distinct types of waterborne acrylics find use in surface coatings, namely: • emulsions • inverted dispersions Acrylic emulsions used in surface coating applications are almost invariably polymerised in water as described in Chapter II. Water dispersible or inverted vinyl or acrylic polymers can be produced by […]

The majority of water reducible resins are used either as additives to increase the viscosity of emulsions or they are used as one of the principal resins in crosslinking systems. Functional groups are incorporated by necessity to obtain water reducibility and either these groups can participate in crosslinking following the evaporation of the amine (or […]