Iron Complex Drier for Alkyd Coatings Resolving Skin Formation
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Solution Overview
Problem
Current non-cobalt drier compositions for alkyd-based coatings face challenges in balancing drying performance and anti-skinning properties, often resulting in either poor drying times or excessive skin formation during storage.
Innovation Solution
A combination of Fe complexes with specific nitrogen donor ligands and metal salts of manganese, cerium, or vanadium, along with certain ligands, is used to enhance drying activity and reduce skinning tendencies without the need for additional anti-skinning agents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If iron complexes with multidentate nitrogen donor ligands are used as driers, then drying efficiency is improved, but skin formation during storage increases
Solution Approach 1:
The drier system is segmented into multiple functional components: iron complexes with multidentate nitrogen donor ligands (providing drying efficiency) combined with specific additives (controlling skin formation). This segmentation allows each component to perform its specialized function without interfering with the other, resolving the contradiction between high drying efficiency and reduced skin formation.
Solution Approach 2:
The invention changes the chemical parameters of the drier system by selecting specific iron complexes with defined ligand structures (tetradentate, pentadentate, or hexadentate nitrogen donor ligands) and controlling the metal salt composition. These parameter changes optimize the catalytic activity for drying while reducing unwanted skin formation during storage.
2Productivity
If cobalt-based driers are used, then drying performance is improved, but health safety deteriorates due to carcinogenicity
Solution Approach 1:
The invention replaces expensive and hazardous cobalt-based driers with iron-based alternatives that are safer and equally effective. This substitution principle eliminates the harmful carcinogenic effects of cobalt while maintaining the required drying performance through optimized iron complex formulations.
Solution Approach 2:
The invention changes the metallic component parameter from cobalt to iron, fundamentally altering the toxicological profile while maintaining catalytic functionality. The iron-based drier system achieves the same drying performance without the carcinogenic hazards associated with cobalt compounds.
3Loss of time
If drier concentration is increased to improve drying speed, then drying time is reduced, but skin formation during storage increases
Solution Approach 1:
The invention changes the chemical nature of the drier system from conventional metal salts to iron complexes with specific nitrogen donor ligands. This parameter change allows for optimized catalytic activity that achieves fast drying at lower concentrations, thereby reducing skin formation while maintaining short drying times.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach achieves drying performance comparable to cobalt-based driers while minimizing skin formation, thereby improving storage stability and drying efficiency.
Implementation Method 1
Autoxidation is a free radical chain process that takes place when alkyd resins are exposed to air. Autoxidation is a free radical chain process which can be subdivided into three stages: chain initiation, propagation, and termination. Once free radicals are formed, they react in a chain and convert the unsaturated moieties of alkyd resins in interpolymer crosslinks.
Implementation Method 2
The drying process of autoxidizable architectural coating compositions takes place at ambient temperatures ranging from 0 to 40° C, whereby the presence of oxygen is essential. Since the drying process proceeds slowly, the chemical conversion of alkyd resins is habitually catalyzed by salts of metal ions as catalytic oil drying agents. These salts of metal ions act as driers or siccatives.
Data Source
AI summary
The invention relates to a drier composition for an autoxidizable alkyd based coating composition, comprising: a) at least one Fe complex comprising Fe and at least one nitrogen donor ligand, wherein said at least nitrogen donor ligand is selected from the group comprising tridentate, tetradentate, pentadentate and hexadentate nitrogen donor ligands; b) at least one metal salt of a carboxylic acid, wherein the metal is selected from the group comprising: Mn, Ce, V, and Cu, preferably Mn; and c) at least one ligand comprising at least one moiety selected from the group comprising 1,4,7-tri-azacyclononanyl, 2,2'-bipyridyl, 1,10-phenantrolinyl, imidazolyl, pyrazolyl, porphyrinyl, aliphatic, cycloaliphatic, and aromatic amines. The present invention also relates to coating composition comprising the drier composition, and the uses thereof.