OXSILAN®
AN INNOVATIVE CHROME-FREE METAL PRETREATMENT TECHNOLOGY.
INTRODUCTION
OXSILAN is a range of Cr-free metal pretreatment products. This technology is based on a series of silanes which exhibit either cross-linking or functional activity in combination to create chemically bonded films on the metal surface, enhancing corrosion resistance and, for organically coated substrates, increasing the bond strength between metal and paint. It was designed to meet the health, safety, environmental and performance requirements of the 21st century. The OXSILAN range exists out of the AL range for Aluminum substrates and the MM range for Multi Metal applications including Cold Rolled Steel and Hot Dip Galvanised Steel. Chromium and phosphating chemistries are a natural target for silanes in preventing corrosion and providing good paint adhesion.
CHEMISTRY
Silanes are of the general form:
R-Si(OX)3, where the OX typically is an alkoxy group. The R group can be non-functional or functional when it contains a reactive organic substituent. In the latter case there the adhesion with specific coatings will be promoted.
Before a silane is able to react with oxides present on the metal surface, it needs to be hydrolysed forming a silanol. Simplified this looks as follows:
R-Si(OX)3 + 3H2O ⇔ R-Si(OH)3 + 3XOH
This hydrolysate should be kept at a pH range of 4-6 to prevent a condensation reaction.
Condensation:
2 R-Si(OH)3 ⇔ R-Si-O-Si-R + 3H2O
The silanol with general formula R-Si(OH)3 reacts with metal oxides and hydroxides which are present on a cleaned metal surface.
OXSILAN AL-0500 A&B
OXSILAN AL-0500 is a multi-purpose, liquid treatment for aluminum. This unique system will enhance the performance of most paint systems and, additionally, inhibit corrosion on non-painted surfaces. OXSILAN AL-0500 consists of two parts (A & B), to provide greater flexibility and can be adapted for most systems processing wrought and extruded aluminum and non-copper bearing aluminum alloys. This flexible system is applicable for high-speed, no-rinse coil lines and can be adapted to conventional parts operations. OXSILAN AL-0500 will replace chromates and other treatments.
PROCESS
The OXSILAN products have been designed to be used in existing facilities
without large investments. They are sold pre-hydrolysed and stabilised in a
concentrated form. For bath make up they require dilution with DI water. Proper
cleaning is essential to obtain a good wetting of the working solution.
Typically the process is as follows:
CLEANING ♦ RINSING ♦ OXSILAN ♦ DRYING
Process charecteristics:
• Application: spray, immersion, roll coater, dip/squeegee
• Reaction time: min. 2 seconds
• Bath temperature: room temperature
• No rinsing required
• Drying temperature: room temperature, but preferably ca.80 deg.C.
• PH range: 4-6
Process Control:
• Solution: Titrations and Spectrophotometric
• Silane Layer: XRF
Ph: (888) 891-0077
Dmail: 411@naltic.com
Headquarters
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299 S Main St Suite 1300
Salt Lake City, UT 84111
USA