1. Rationale
Justification for Revision: Continuation of work item WK35399. This is a new ballot with new wording to address concerns about removing the base polymeric adhesive raw material from the standard. These concerns have merit. The proposed wording for this ballot leaves in the current wording and adds the use of 25% Maleic Anhydride Grafted Polymer which has been partially hydrolyzed as an acceptable polymer coating. The justification for this revision is that advancements in polymer science and technology have yielded Maleic Anhydride grafted polymeric adhesive materials which are capable of bonding to the metal surface. These materials can be and currently are produced as film coatings fully capable of being laminated to a sheet specified in 6.1 and meet the testing called out in 7.1 to 7.9 of the standard. Maleic Anhydride has been used for bonding to metal surfaces for some time and is well known to those in the art of metal lamination and powder coating. The Maleic Anhydride chemical reaction to the metal surface employs the same carboxylic acid group bonding mechanism as acrylic acid based polymers such as ethylene acrylic acid, EAA. The carboxylic acid groups for both of these polymeric adhesives use coordination chemistry to form bonds to the metal atoms and thus improve the bonding of the polymer coating to the substrate. This bonding results in comparable adhesion for both additives. In order to ensure acceptable bonding the Maleic Anhydride ring grafted to the polymer is partially hydrolyzed in the laminate film extrusion process using compounds capable of donating hydroxide anions. This process opens up the anhydride ring forming the aforementioned carboxylic acid group which bonds to the metal atom. The Hydrolyzation modification of MA modified polymer laminate ensures processing and reaction bonding rates equivalent to that provided by EAA modified polyethylene laminate.
Keywords
aluminum-mischmetal alloy; aluminum-mischmetal alloy coated; coatings-55 % aluminum-zinc alloy; coatings-metallic; coatings-polymer; coatings-zinc; coatings zinc 5 %; corrugated steel pipe; pipe-corrugated steel; polymer coatings; steel sheet-55 % aluminum-zinc alloy coated; steel sheet-metalic coated; steel sheet-polymer coated; steel sheet-zinc coated; steel sheet-zinc 5 %; Alloy steel sheet/strip--specifications; Corrugated steel sewer/drain pipe--specifications; Drain/waste/vent (DWV); Metallic steel sheet--secifications; Polymer coatings--steel; Sewer pipe (steel)--specifications; Steel pipe--specifications; Steel sheet--specifications ;
Citing ASTM Standards
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