Patent Application
20080051526
The coating composition of the present invention includes PUPO and iron carbonyl. Preferably, it also includes other resins and a variety of additives. Polyester resins, epoxy resins, phenoxy resin, etc., can be included in the coating composition.
Preferably, the PUPO in the composition has both flexibility and crosslinking ability. Means for achieving such a PUPO composition are apparent to those skilled in the art. For example, a single PUPO could have both flexibility and crosslinking ability, two or more PUPOs can be combined to achieve PUPOs that are flexible and ones that are self-crosslinking, a flexible PUPO can be combined with a more traditional blocked isocyanate, etc. The present inventors have tried to increase flexibility using a flexible PUPO with a long chain alcohol group on an isocyanate arm, e.g., Setal 10-9448 from Nuplex Resins. A separate PUPO was utilized by the present inventors to provide crosslinking ability by means of a partially blocked isocyanate (this PUPO is referred to as a modified PUPO in the formulations and is proprietary to Akzo Nobel). However, it is apparent to the skilled artisan that a single PUPO could be provided which has both flexibility and crosslinking ability.
Akzo Nobel's proprietary modified PUPO (used in the formulation examples) is modified by substituting some of the diols with that of a blocking agent that, under high temperature conditions (above 350 F.), will unblock to yield free isocyanate groups that can further react with other hydroxyl-containing compounds. Blocked isocyanates are described in the patent of Bayer Aktiengesellschaft (U.S. Pat. No. 3583943A)
The coating composition can also contain a high molecular weight phenoxy resin (e.g., wt. avg. MW 40,000-60,000). A representative example is Paphen PKHS 30 PMA, available from Phenoxy Assoc. This resin has been found to work well together with the PUPO and iron carbonyl of the inventive composition. A lower molecular weight epoxy resin can also be used.
Additives used in the inventive composition include those generally found in coating compositions. In particular, the inventive composition preferably includes one or more corrosion inhibitors (usually chromate-containing or chromate-free pigments (e.g., Calcium ion exchange silica, e.g., Shieldex AC5, available from Davison Grace)), one or more lubricants (organic (e.g., polytetrafluoroethylene (PTFE), etc.) or inorganic (e.g., graphite, boron nitride, molybdenum disulfide, etc.)), one or more suspension agents (e.g., clay (e.g., Tixogel MP 250, available from Sudchemie), etc.), in one or more solvent carriers.
Surprisingly, the unique combination of two lubricants, molybdenum disulfide and PTFE powder, provides formability of parts without putting undo stress on the fabrication dyes. For example, the inventors have tried Moly disulfide Tec, available from Amax Inc. and Micropower S1100, available from ISP, but these lubricants are available from other sources as well.
Representative examples of solvent carriers include, but are not limited to:
The coating composition of the present invention is intended for use on metal substrates, but use on other substrates is not discouraged. Such metal substrates may be pre-treated and can include many zinc alloys, e.g., EG steel, hot dip galvanized, Galvanneal, etc.
The inventive coating composition can be applied by any known coil coating method. Further, it can be formed with a variety of techniques, including blanking dyes, hydroform, etc., without losing its weldability and corrosion-resistant properties.
In addition to excellent weldability and corrosion resistance, the inventive coating composition exhibits improved adhesive substrate bonding characteristics and a smoother finish. Another important advantage of the invention is that it obtains all of these benefits at very low dry film thicknesses (e.g., about 1 to about 10 microns dry film thickness (DFT), usually about 3 to about 5 microns DFT).
The invention is further illustrated in the following Examples which, however, are not intended to limit the same.
Formulation Example 2 was coated on panels which were subjected to cyclic tests of repeating cycles of humidity, salt, high temperature and dry conditions. The results of these tests are shown in
In one example, the coating composition is cured in the oven at about 430 F. peak metal temperature (PMT), wherein it cures in about 30 seconds at an oven temperature of about 750 F. However, other means of cure, temperature for curing, etc. are possible and apparent to the skilled artisan.
The invention is further illustrated by the following claims, which, however, do not limit the scope thereof.
This application claims priority based on U.S. Provisional Application Ser. No. 60/618,888, filed Oct. 14, 2004.
| Number | Date | Country | |
|---|---|---|---|
| 60618888 | Oct 2004 | US |
