Schwego Corrit A Paint Additive Against Residual Rust

Transcription

1 Schwego Corrit A Paint Additive Against Residual Rust Description Schwego Corrit is used in waterbased systems as an autonomous corrosion protection additive. It can also be combined with zinc phosphate resp. other pigments and thus it can be incorporated in primer finishes as an additional long term corrosion protection additive. Typical applications : DIY systems Maintenance paints One coat corrosion protection primers Corrosion protection primers Practice The effectiveness of anticorrosive coatings mainly depends on the thoroughness of the substrate pretreatment. A thoroughly derusted, dry and fatfree substrate is a precondition for long term protection against corrosion. These optimum conditions are not often available in practice : Residual rust frequently remains on the surface and in the pores. The coating appears to confer satisfactory protection against rust. Result after several months : rust destroys the new coating from below. Solution The paint additive Schwego Corrit passivates existing residual rust by changing it to a very stable metal complex. The result is a lasting corrosion proteciton. It aids substrate wetting and improves the adhesion of the coating. Paints containing Schwego Corrit can be applied directly onto rusty surfaces after removal of loose rust particles. Composition Schwego Corrit is a paint additive based on a chelate forming agent and a wetting agent component

2 Mode of action As the structure of the unstable Fe3 formed during air oxidation is porous it does not prevent further air and moisture from coming into contact with the metal. Finally the metal is completely rusted. The functions of Schwego Corrit are : a) to prevent the contact of materials that have a corrosive effect (mechanical effect) or / and b) to interfere into the electromechanical corrosion process in such a way that it is prevented or at least slowed down (electromechanical process). Schwego Corrit helps to protect the material from corrosion by activating both protection mechanisms, as the chelate forming agent of Schwego Corrit forms a virtually insoluble chelate complex with the Fe-ions that are present in the rust layer. Due to the insolubility of the chelate complex the Fe-ions are linked so tightly that they cannot continue the electro-mechanical corrosion. Thus a barrier is formed that makes it practically impossible for the oxygen to attack metallic substrate. The result is a stable metal-organic layer adhered to the metal surface that will no longer oxidize. So not only is a highly effective and durable corrosion protection is achieved but additionally there is virtually a chemical linkage between the metallic substrate and the organic coating.

3 Testing : When testing a coating system containing Schwego Corrit it is essential that the test substrates show residual rust (at least an oxidated surface). A rusty panel should be roughly derusted for your own lab tests. Especially if the resin is rather alkaline a predilution is recommended and the Schwego Corrit should be added very slowly and carefully to avoid local overdose that will result in specks which are difficult to destroy. For this most common solvents can be used, i. e. glycol, higher alcohols, water, etc. By doing this we found no problems with any of the cross-section of commonly used resin types we tested. Whenever possible Schwego Corrit should be added at the beginning to the mill base. But it is also possible to add it afterwards. In this case a predilution is advisable as described above and the product should be added with high shear rate. We recommend evaluation of the Schwego Corrit using outdoor weathering. Accelerated weathering tests (e.g. salt spray test) give misleading practical values because of the high initial deterioration. In the sample bottle it could happen that the surface of the product turns to green gradually. This shift in colour is not a precipitation but a "cosmetic" problem. This does not affect the properties or the effectiveness of the product but influences only its appearance. The change in colour is caused by a very little oxidation of the air and the formation of this oxidation product is reversible. That means it will be immediately destroyed when the Schwego Corrit reacts with the iron surface. Unfortunately the shift in colour is visible at concentrations on the ppb level.

4 ****************Formulation suggestion********************* Description: Acryl-thick film paint- white contains SCHWEGO CORRIT high gloss Basis : Primal HG 76 pure acrylate dispersion composition: TiO (Kronos) 30,0% Schwego PUR 8020 (Schwegmann) 0,5% Schwego PUR 8050 (Schwegmann) 0,5% Propyleneglycole 8,0% Water 5,8% SCHWEGO CORRIT (Schwegmann) 1,0% Dissolve up to a fineness of grind 20my then prepare the binder and incorporate the paste slowly Primal HG 76 (Rohm&Haas) 47,1% add slowly while stirring Blister Free 45 (Schwegmann) 0,5% Schwego Wett 8090 (Schwegmann) 3,5% Schwego Flow 8058 (Schwegmann) 1,0% Preserving agent 0,1% Texanol 2,0% stir well and slowly add Antigel Antigel (Schwegmann) 1,0% Total formulation amount: 100 % Disperse the items 1 to 5 finely up to 20my, then prepare item 6 and incorporate the paste slowly

5 then add the items 7 up to 10 slowly and stir well at least 15 minutes, then add item 11 slowly ****************Formulation suggestion********************* Description: Acryl silk flat finish black contains SCHWEGO CORRIT Basis : Liocryl AM 912 pure acrylic, without solvents and plasticizers Composition: Water 10,0% Propylene glykol 8,0% Schwego PUR 8050 (Schwegmann) 1,0% Schwego PUR 8020 (Schwegmann) 0,3% SCHWEGO CORRIT (Schwegmann) 1,0% premix well, then add: Liocryl AM 912 (Synthopol) 68,9% Colanylschwarz (black) (Hoechst) 8,0% Texanol (Eastman) 2,0% Blister Free 56 (Schwegmann) 1,0% Matting agent OK 500 (Degussa) 0,8% Total formulation amount: 100% Thoroughly premix the items 1 to 4, then incorporate the items 5 to 9 while agitation

6 ****************Formulation Suggestion********************* Description: aquous metal primer grey around RAL7000 contains SCHWEGO CORRIT Basis : Neocryl XK 62 styrene-acrylate dispersion Composition: Butyldiglykol 5,00% Schwego Wett 8075 (Schwegmann) 2,50% Schwego Flow 8058 (Schwegmann) 2,50% Blister Free 56 (Schwegmann) 1,50% Schwego PUR 8050 (Schwegmann) 2,00% Schwego PUR 8020 (Schwegmann) 0,50% SCHWEGO CORRIT (Schwegmann) 1,0 % premix TiO 2 Kronos 2190 (Kronos) 6,00% Silicic acid HDK N20 (Wacker) 0,50% Halox BW 191 Lawrece Industries) 4,00% Microdol extra (Omya) 11,00% Disperse up to a fineness of grind of my around 20min then prepare the following items and add the above mentioned paste slowly and stir Neocryl XK 62 (Zeneca) 61,29% Texanol (Eastman) 2,00% Colanylschwarz (black) N131 (Hoechst) 0,20% Colanylblau (blue) B2G100 (Hoechst) 0,01% Total formulation amount : 100,0% Weigh the items 1 up 6 and mix them well, then add the items 7 to 10 and mix them, disperse them with the use of a dissolver up to a fineness of 15 to 20 my Prepare item 11 and slowly add the white paste, then slowly add the items 12 to 15 while stirring

7 ****************Formulation Suggestion********************* Description: aqueous metal primer red oxide contains Schwego Corrit 3% Basis : Alberdingk AS 2681 Acrylate acid ester Composition: destilled H 2 O 10,40% Dowanol DPM 3,80% Schwego Foam 8013 (Schwegmann) 0,60% Talkum AT extra (Norwegian Talc) 5,00% Microdol Extra (Omya) 8,00% Zinc phosphat ZP 10 (Heubach) 10,00% Zinc white Harzsiegel (Heubach) 0,50% Bayferrox 130 M (Bayer) 8,50% Schwego Pur 8050 (Schwegmann) 1,20% propylene glycol 11,00% Schwego Corrit (Schwegmann) 3,00% Dissolver and then up to a fineness of grind of my around 20min then prepare the following items and add the above mentioned paste slowly and stir Alberdingk AS 2681 (Alberdingk & Boley) 30,00% Haftharz EP-DS 1300 (Degussa Hüls) 3,00% Kunstharz EP-DS 50 (Degussa Hüls) 5,00% Total amount of the formulation: 100% Weigh the items 1 up to 10 and dissolve them, then add item 11 and disperse them with the aid of a dissolver up to a fineness of my. Prepare the items 12 to 14 and add them to the colour paste. For the adjustment of the viscosity : proplene glycole Additional hints : Schwego Corrit has been incorporated into this corrosion protection primer, because this product converts existing corrosion and it so prevents from the danger of rust beneath the paint. Therefore this corrosion protection primer has an improved adhesion and protects against rust well.

8 ****************Formulation suggestion********************* Description: Acryl-thick film paint- light grey contains SCHWEGO CORRIT high gloss Basis : Primal HG 76 pure acrylate dispersion composition: TiO Kronos 30,0% Schwego PUR 8020 (Schwegmann) 0,5% Schwego PUR 8050 (Schwegmann) 0,5% Propyleneglycole 8,0% Schwego Wett 8090 (Schwegmann) 3,5% Water 5,8% Schwego Foam 8325 (Schwegmann) 0,4% SCHWEGO CORRIT (Schwegmann) 1,0% Dissolve up to a fineness of grind 20my then prepare the binder and incorporate the paste slowly Primal HG 76 (Rohm&Haas) 47,1% add slowly while stirring Schwego Flow 8058 (Schwegmann) 1,0% Preserving agent 0,1% Texanol 2,0% Schwego Fluor 8039 (Schwegmann) 0,1% Colanyl black (Hoechst) 1,0% Total formulation amount: 100 % Disperse the items 1 to 5 finely up to 20my, then prepare item 6 and incorporate the paste slowly then add the items 7 up to 10 slowly and stir well at least 15 minutes, then add item 11 slowly