Coated Effect Pigments Spontaneous Precipitation Binder
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Solution Overview
Problem
Existing methods for coating effect pigments with organic binders face challenges such as separation issues in powder coatings, limited shelf life, and high production costs, particularly in dry-blend and bonding processes, which affect the hiding power and corrosion protection of metallic effect pigments.
Innovation Solution
A method involving the spontaneous precipitation of polymers in organic solvents to create a binder with a crystalline and amorphous fraction, applied to platelet-shaped substrates, which enhances the binding of effect pigments with powder coatings, improving shelf life and reducing separation tendencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If dry-blend process is used to mix effect pigments with powder coating, then the process is simple and quick, but the effect pigments separate from the binder during application due to different specific weights and electrostatic charging behavior
Solution Approach 1:
The patent applies preliminary action by pre-coating the effect pigments with binder before mixing with the powder coating. This preliminary coating step ensures that the pigments are already bound to the binder, preventing separation during application. The coated pigments are then mixed with the powder coating in a dry-blend process, combining the benefits of simple mixing with improved stability.
2Stability of the object's composition
If bonding process is used to attach effect pigments to powder coating particles by heating, then adhesion is improved and separation is reduced, but local overheating causes unwanted hardening reactions and deposit formation
Solution Approach 1:
The patent extracts the heating step from the bonding process, eliminating the source of local overheating problems. Instead of applying heat to bond the pigments to the powder coating particles, the invention uses a chemical coating approach where binder is applied to the pigments at ambient or controlled temperatures, avoiding thermal damage while achieving sufficient adhesion.
3Stability of the object's composition
If bonding process is used to achieve adhesion of effect pigments to powder coating surface, then separation during application is reduced, but only maximum around 7 wt % of effect pigment can be introduced which is insufficient for adequate hiding power
Solution Approach 1:
The patent applies preliminary action by pre-coating the effect pigments with binder before mixing with the powder coating. This allows a much higher concentration of effect pigment (up to 20 wt % or more) to be incorporated while maintaining stable adhesion, as the pigments are already bound to the binder and will not separate during application.
4Ease of manufacture
If effect pigments are not completely enveloped by binder during coating, then the coating process is simpler, but corrosion protection is insufficient because metallic effect pigments are not fully surrounded by binder
Solution Approach 1:
The patent applies parameter changes by adjusting the binder concentration, coating conditions, and binder composition to achieve complete envelopment of the effect pigments. By optimizing these parameters, the binder fully surrounds the metallic effect pigments, providing adequate corrosion protection while maintaining a relatively simple coating process.
5Strength
If reactive binder is used in coated effect pigments, then binding strength is improved, but the products suffer agglomeration due to partial onset of binder crosslinking during prolonged standing times at high temperatures
Solution Approach 1:
The patent applies preliminary action by pre-coating the effect pigments with binder before final product formation. This allows the binder to be in a controlled state during storage, with crosslinking initiated only at the appropriate time during application or curing, preventing premature agglomeration while maintaining strong binding properties.
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
The method provides coated effect pigments with improved shelf life, reduced separation, and enhanced hiding power, while maintaining the optical qualities and chemical stability of metallic effect pigments, thus addressing the limitations of previous technologies.
Implementation Method 1
The invention relates to the coating of effect pigments with organic binders by spontaneous precipitation
Data Source
AI summary
The invention relates to coated effect pigments, wherein the coating comprises a binder which is suitable for powder paints. They comprise a crystalline and an amorphous fraction which is determined by C13 NMR MAS relaxation measurements, the relaxation of the 13C cores being fitted as a biexponential relaxation according to the formula (II) and the degree of crystallinity c being in a range between 40 to 85%, and relaxation having a short average relaxation time T1s and a long average relaxation time T1l, and T1l being in a range of from 65 to 130 s. The effect pigments coated according to the invention have at least one endothermic peak with a maximum from a range of Tmax=100 to 150° C. and an enthalpy ΔH associated with said peak from a range of 15 J/g to 80 J/g in DSC at a feed speed of 5° C./min, the enthalpy being calculated relative to the amount of the binder. The binders are applied to the effect pigment by way of spontaneous precipitation.