Лако-красочные материалы — производство

(i) Stabiliser Components FORMULATION 2-8 Styrene 69.70 Acrylic acid 29.70 Initiator 0.60 Total 100.00 The polymerisation is a bulk process which is a very reactive and strongly exothermic process, thus a special reactor with efficient cooling is required. Solvent is not available to control the reaction by refluxing and thereby removing the heat of reaction. […]

In this example the use of a Redox initiator to start the polymerisation at a low temperature is illustrated. Previous examples have described isothermal polymerisations, but this reaction pattern is commonly used in industry as it reduces the need for cooling. On a large reactor, the heat required to raise the temperature would be provided […]

As with the last example, this formulation uses the pre-emulsified monomer technique. FORMULATION 2-5 Reactor charge Water 15.0 Stabilising colloid 1.0 Ammonium persulphate 0.1 Pre-emulsion vessel charge: Water 44.9 Styrene 21.0 n-Butylacrylate 12.0 Hydroxyethyl methacrylate 5.0 Emulsifier 0.5 Colloid 0.5 Total 100.00 Procedure 1. Prepare the pre-emulsion by mixing the monomers with the emulsifier and […]

This formulation utilises a pre-emulsified monomer phase which is added continuously throughout the polymerisation. FORMULATION 2-4 Reaction vessel charge Water 18.50 Protective colloid 0.25 Ammonium persulphate 0.22 Ammonium hydroxide (25% soln) 0.50 De-foaming agent 0.05 Pre-emulsion vessel charge Water 30.18 Styrene 23.00 Butyl acrylate 24.00 Methyl methacrylate 1.00 Colloid 2.00 Di-methyl ethanolamine 0.30 Total 100.00 […]

This example illustrates a graft polymerisation in which colloid stabilisation and both Redox and thermal initiation techniques are employed. The reaction in effect takes place in two stages, with the vinyl acetate polymerisation taking place before the acrylic monomers are polymerised. Thus a random copolymer will not result and reaction conditions are such that grafting […]

1. A solution of hydroxy ethyl cellulose is made in de-ionised water. To this solution is added the sodium dodecylbenzene sulphonate, ammonium acetate and ammonium persulphate. 2. 25% of the vinyl acetate and 16% of the methyl methacrylate are added and the reaction vessel is heated to the reflux temperature of the vinyl acetate (the […]

In this example, a copolymer of vinyl acetate (VA) and methyl methacrylate (MMA) is formed. As in the last example, a single surfactant and initiator are used and added to these are a buffer and a protective colloid. Nitrogen is not required as the vapour pressure of vinyl acetate monomer ensures that an oxygen free […]

1. Methyl Methacrylate Homopolymer: This example is the simplest formulation for an emulsion polymerisation consisting of one of each of the four essential components i. e. water, surfactant, monomer and initiator. FORMULATION 2-1 De-ionised water 59.5 Sodium lauryl sulphate 0.8 Ammonium persulphate 0.1 Methyl methacrylate 39.6 Total 100.0 Manufacturing Procedures 1. An aqueous phase is […]

The process of film formation is a crucial factor in achieving optimum performance from a water based emulsion. Ideally, the polymeric, spherical particles should coalesce to form a fully coherent film, free from imperfections. This coalescing process has been thoroughly studied by many workers over the years. Techniques such as scanning electron microscopes (SEM), small […]

Hydrophobic groups are polymerised into the backbone of the polymer chain so that they are pendant to the backbone along with the carboxyl. This class of thickeners is described as ‘associative’ since the hydrophobic groups associate with emulsion particles present, through adsorption onto the particle surface. In addition, they aggregate together in the water phase […]