{"id":7481,"date":"2017-12-01T08:00:28","date_gmt":"2017-12-01T14:00:28","guid":{"rendered":"https:\/\/www.ulprospector.com\/knowledge\/?p=7481"},"modified":"2017-12-08T12:24:03","modified_gmt":"2017-12-08T18:24:03","slug":"lmf-zddp-accidental-additive","status":"publish","type":"post","link":"https:\/\/ulprospector.ul.com\/7481\/lmf-zddp-accidental-additive\/","title":{"rendered":"ZDDP: The Accidental Additive"},"content":{"rendered":"

You may have heard of the lubricant additive zinc dialkyldithiophosphate (ZDDP), but did you know its unique antiwear applications were discovered serendipitously?1<\/sup><\/p>\n

ZDDP: A historical perspective<\/strong><\/h3>\n

ZDDP was first introduced as a lubricant additive in 1941, when three different companies\u2014Lubrizol, American Cyanimid, and Union Oil Co.\u2014filed patents with claims of corrosion and oxidation inhibitors in engine oils.2<\/sup> It was likely that ZDDPs were first used in engine lubricants in the late 1930s.3<\/sup><\/p>\n

In the late 1940s, V8 engines with overhead valves and increased compression ratios were introduced. This design increased stresses on valve train components, and cam and follower wear. As engine lubricants containing ZDDP were already in use, it was observed in the 1950s that those containing ZDDP provided antiwear properties. The automobile industry quickly adopted the use of ZDDP in high-quality motor oils, and now employ their use in practically all current engine oils.3<\/sup><\/p>\n

What are zinc dialkyldithiophosphates?<\/strong><\/h3>\n
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Structure of a monomeric zinc dialkyldithiophosphate<\/figcaption><\/figure>\n

 <\/p>\n

ZDDPs are a family of uncharged compounds composed of zinc, phosphorus and sulfur traces that are, as mentioned above, primarily used as antiwear additives in lubricants, such as greases, gear oils, and motor oils.4<\/sup>\u00a0<\/sup><\/p>\n

Zinc is bound to the anion of dialkyldithiophosphoric acid (e.g.\u00a0ammonium diethyl dithiophosphate).3 <\/sup>The compound is also known as ZnDTP and ZDP.4<\/sup>\u00a0<\/strong><\/p>\n

ZDDP characteristics<\/strong><\/h3>\n

Spikes argues that ZDDPs are \u201cthe most successful lubricant additive ever invented,\u201d as no other cost-effective compound has shown comparable antiwear performance in engine oils.3<\/sup> The properties can vary depending on heat and the ratio of zinc oxide to the dialkyl dithiophosphoric acid, creating acidic, neutral and basic ZDDPs, each with a different reactivity.4<\/sup> Here are a few applications:<\/p>\n