29 июля, 2015 
Malyar Thermoplastic acrylics are used extensively in aerosol lacquers, both as solid colours and metallics, in touch up automotive refinish applications. Due to their excellent colour, colour retention, rapid drying, relative inertness to metallic and fluorescent pigments, and exterior durability, they are also used for small household jobs such as repainting furniture (chairs, stools), metal coatings, marking paints etc.
As aerosol cans are such inefficient spray applicators, paints of very low viscosity are necessary in order to achieve good atomisation and prevent ’cobwebbing’. Aerosol paints have extremely low solids (less than 10% when combined with the propellant) and viscosties. Fluoro hydrocarbons were standard propellants in use about ten years ago, but for environmental and economic reasons, they have been replaced by propane/butane mixtures or dimethyl ether. The latter propellant offers better compatibility with high molecular weight resins. Typical levels of propellant lie in the region of 20-30% by wt of the total formulation. High boiling, strong solvents are used as diluents to avoid too rapid drying and to improve compatibility with the propellents.
Starting point formulations are given below <2).
CLEAR LACQUER FOR AEROSOL COATING
|
Paraloid B48N (50% nvc content) |
35.00 |
|
Toluene |
8.75 |
|
Xylene |
42.25 |
|
PM Acetate |
14.00 |
|
Total |
100.00 |
B48N is the preferred resin because of its adhesion to bare metals such as chrome. Paraloid B66 can be used for pigmented refinish (Duplicator license)
Paraloid B66 is a Tg 50°C MMA/BMA copolymer, 50% nvc in toluene. For exterior car touch up enamels, it is recommended that a UV absorber system is incorporated into this formulation.
WHITE LAQUER FOR AEROSOL COATING
|
Sand Mill Rutile titanium dioxide Paraloid B72 (50%) Xylene PM Acetate Let down |
6.40 1.60 3.60 1.20 |
|
Paraloid B72 (50%) Toluene Xylene PM Acetate Flow additive |
17.60 4.40 42.30 22.80 0.10 |
|
Total |
100.00 |
Paraloid B72 is an ethyl methacrylate (EMA) copolymer, Tg 40°C, 50% nvc in toluene. It has low reactivity with sensitive phosphorescent and luminescent pigments, and produces stable, durable non-yellowing coatings. It is compatible with vinyls, cellulosics, chlorinated rubbers and silicones, and is used in clear, metallic and solid colour formulations.
METALLIC LACQUER FOR AEROSOL COATING
|
Premix Aluminium Leafing Powder (Alcoa No. 422) Paraloid B72 (50%) Toluene Let down |
4.80 22.40 5.60 |
|
Toluene Xylene Flow additive |
14.50 52.3Q 0.4Q |
|
Total |
100.00 |
The above formulations are filled into the aerosol can, together with the propellant mixture at a 70/30 paint/propellant ratio.
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Commercial resins recommended for aerosol spray applied coatings include :
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 Опубликовано в рубрике Waterborne & Solvent Based Acrylics and their End User Applications
Видео производства фасадной краски:
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