Clearclad HD Data Sheet .... ()

1. PRODUCT DESCRIPTION

CLEARCLAD HD is a general purpose cathodic electropaint which offers an attractive combination of properties including high clarity, excellent resistance to chemicals and UV light, good corrosion protection over a wide variety of metals; especially zinc die-castings and steel, and versatility in its ability to be "tinted" or pigmented in order to achieve an extensive range of decorative finishes. Base resin variants exist as follows:

 
2. SUPPLY FORM

The base resin concentrate of CLEARCLAD HD is a tan colored, free flowing liquid of moderate viscosity. Pigmented and matte variants will vary in appearance and viscosity accordingly.

Packaging is 20 kg American Pails. Other packing types and sizes may be available on request.
 

3. SUPPLY SPECIFICATION

This will vary according to product type. The base resin concentrate is supplied in ready-to-dilute form, solids content 45 - 50% by weight (determined gravimetrically at 120oC for 1 hour).
 

4. METHOD OF DILUTION

CLEARCLAD HD concentrates should always be pre-mixed with either high purity demineralised water, or bath material at coating solids, when making a new bath or replenishing an existing bath respectively.

Pre-mixing must take place in a suitable clean vessel equipped with a motorized stirrer. Diluting material is added gradually to the concentrate, under stir, until a solids content of less than 18% is achieved. At this stage, at least 10 minutes stirring is applied to achieve complete emulsification. Subsequently, this pre-mix may then be further diluted to the required solids or added to the bath as appropriate.

CLEARCLAD HD concentrates must never be added directly into demineralised water or into the bath without this pre-mixing procedure.
 

5. CONDITIONING OF NEW BATHS

A period of at least 24 hours, and preferably 48 hours, should elapse between initial bath make up and commencement of production. During this time, the bath should be kept circulating through adequate particle filtration at its normal operating temperature, and at least one bath volume of ultrafiltrate permeate should be eliminated. Solvent loss due to permeate elimination is not significant, but the MEQ (corrected) should be maintained at a minimum value of 30 by appropriate additions of CLEARCLAD Emulsion Stabilizer.
 

6. BATH OPERATING PARAMETERS

 
7. ASSESMENT OF CURE

This appropriate degree of cure (polymerization) should be established for the particular application and this should be related to the resistance to a solvent rub test. In this way, a quick ens-of-line test for correct degree of cure can be established. Obviously, this is a destructive test even in the case of a pass, and so when it is applied to selected production pieces as part of a quality control procedure, the pieces should be discarded or re-worked as appropriate.
 

8. COVERING POWER

One kilo of the base resin concentrate of CLEARCLAD HD will apply a coating of 1 micron over approx. 450 sq.metres assuming 100% efficiency.

Near to 100% efficiency can be achieved using closed-loop ultrafiltration reclaim. Without a reclaim system, efficiency and consequently covering power will reduce.

"Tinted" systems, using relatively low concentrations of colorants, will have covering power very similar to the base resin concentrate. Other types of pigmented systems, incorporating significant concentrations of dense colorants or matting agents will have lower covering power. This will depend entirely on the particular product and such information will form part of the appropriate data sheet.
 

9. RESISTANCE OF CLEARCLAD HD COATING TO ULTRAVIOLET LIGHT

In addition to CLEARCLAD HD's outstanding resistance to a great variety of chemicals, it has been formulated to have high resistance to UV light in order to render it suitable for exterior applications where resistance to the effects of weather is essential. As a transparent coating, its UV resistance is comparable to the best available exterior-quality acrylics or polyesters. However, its principal advantage is in being able to provide the well established "tinted" simulation of colored metals onto reflective "white" metal substrates, but with at least ten times the color change/fade resistance achieved with previous similar systems. (assessment using DE measurements according to the CIELAB system after exposure to minimum 500 hours QUV UVB).

LVH have developed a colorant system which will achieve yellow metal effects from "brass" through "gold" to "bronze", the actual color being determined by a combination of the mixed colorants and the color of the base metal.

Other colored "tints" in addition to hard colors including white and black in a range of gloss values may be formulated on request.
 

10. CORROSION PROTECTION AFFORDED BY CLEARCLAD HD COATING

The resistance to corrosion of any coated metal is always determined by the particular "system" - which means a combination of the base metal, its pretreatment, the type of coating applied, and the thickness and type of pigmentation of the coating.

CLEARCLAD HD is effectively a one-coat paint system. Accordingly, its corrosion-protective properties will be principally influenced by its thickness and quality of adhesion to the base metal. In this way, HD will provide a barrier (optimized by its thickness) to corrosive agents, and a resist against spread of corrosion (optimized by its adhesive strength). Further than this, the intrinsic corrosion resistance of the base metal should be optimized, for example by the chromating of brass and zinc. Proper preparation of the base metal will both increase the intrinsic corrosion resistance and enhance the adhesion of HD, both factors combining to optimize the corrosion resistance of the whole system.

Specifically for zinc and brass, HD Interpas has been designed to give enhanced corrosion protection. The improved performance may be achieved without chromate passivation if environmental of effluent considerations are paramount. HD Interpas will enable about 80% of the performance achieved by chromate passivation. If HD Interpas is used in conjunction with chromate passivation --a so-called "embedded" system-then outstanding corrosion resistance is achieved.

Note: that for significant corrosion protection without change in decorative properties, electropassivation using weak dichromate-based processes is preferred over simple immersion passivation using chromic acid based processes.
 

11. WEAR AND ABRASION RESISTANCE

CLEARCLAD HD has good intrinsic abrasion resistance (as determined by ASTM D968 Falling Sand test - 25 litres/25 micron thickness) over a wide range of cure levels. This in combination with it being a high-build product (20 micron thickness readily available) affords a high degree of wear and abrasion protection. As the absolute wear property of organic coatings is principally a function of thickness, applications demanding wear resistance should utilize the higher thickness available with HD.

Mar resistance may be enhanced by the addition of HD slip aid. This will increase resistance to metal marking and superficial scratching which is useful for decorative components with flat surfaces. However, this does not increase the intrinsic abrasion resistance as measured by the ASTM D968 test.