The formulation Design Research of Electrically Conductive Putty
Traditional methods of corrosion protection for metals are: plating, powder paints and liquid paints.The performance of the coatings sprayed by all kinds of coatings,as well as different spraying methods vary, but in general, compared to liquid paint coatings, and plating coating, powder coatings give a dense structure with coating thickness (0.02-3.0mm), good shielding effect for various media, this is the reason of powder coated substrate gives longer life expectancy.
Powder coatings,in the process,present with great variety,high efficiency,low cost,easy to operate,no pollution and other characteristics of performance, in products with anti-corrosion,decorating,electrical insulation,long life and other advantages.Therefore,powder coatings can ,in many ways,replace the traditional liquid paint for anti corrosion,show all the time its increasing charm in material energy saving and decorative field .
The quality of powder coated workpieces mainly depend on the quality of pre-treatment before spraying. Electrostatic spraying powder coatings do not need drop priming,so it require high quality of the surface of the substrate.However,the workpiece to be coated usually show uneven surface with easily scratch and hurt seriously. For these workpieces,the electrically conductive putty must be used to fill uneven surface to guarantee its decorative and protective performance. However,the Electrically Conductive Putty sold on the domestic market gives poor electrostatic conductivity,low rate of the powder and extreme unsatisfactory results.The conductive adhesion imported of give a good conductivity,high rate of the powder usage ,but very expensive.
The conductive putty presented in this paper show a good adhesion and conductivity, raw materials are easily to get ,itsrecipes simple and easy to use, cheap, pollution-free,and better ensure the quality of pretreatment for electrostatic powder coating .
1.The formulation design
To get the best formulation of conductive putty, three kinds of designed formula are prepared to conduct research and comparison.
(1)The quality of the Electrically Conductive Putty on the market is not good, to which the aluminum paste is added to increase its electrical conductivity;
(2)To add aluminum paste to epoxy putty used in the liquid paint spraying process .
(3)To add adhesive to aluminium paste.
Conductive putty is usually required for electrostatic spraying in pretreatment process, it requires not only a good conductive performance, but also the ability of temperature resistance of 180 degrees Celsius,as well as a good adhesion with metal, so this formula choose a special adhesive with good media resistance (as oil, and water, and acid, and alkali,) good characteristics of bond with metals , low temperature drying, high temperature resistance, no poison and cheap cost ,etc .
2.Formula comparing results
According to the above three formulas ,three types electric conductive putty shall be prepared, then to use them for workpiece with similar surface defects with passivation pretreatment of aluminum or galvanized steel, finally the comparison experiment shall be carried out by electrostatic spray .
Oil ,rust removal – dry – put conductive putty – dry -powder coating process – drying
- (1)Adding a small amount of (5%-10%) aluminum paste in conductive putty , the conductivity would be increased slightly, but adhesion of putty to the substrate is significantly reduced and hard coated, the conductivity is still not satisfactory;
- (2)The formula give good adhesion of putty to substrates , but the conductivity is not ideal;
- (3)This putty is made of joining total 3%-15% aluminum paste in the selected adhesive , experiment proves that it gives good adhesion and conductivity, non-proliferation, excellent coating color,good flexibility and strength impact properties.
To sum up, the formula 3 is the best idea option of conductive putty .
Testing experiment presents the idea formula of conductive putty – joining 3-15% aluminum paste in the selected adhesive. This formula is simple, and nontoxic, gives good adhesion and conductivity, fast drying (60 Celsius degrees, 1 hours or at room temperature 1 day ), can significantly improve products quality, lifetime and economic benefit, has better application prospects.