One-Component Powder Coating Matte Finish via Inorganic Additives
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Solution Overview
Problem
Conventional powder coating compositions face challenges in achieving a matte appearance while maintaining processability and avoiding the use of expensive, incompatible resins, especially when curing at low temperatures.
Innovation Solution
A one-component powder coating composition is developed, featuring a curing system with a curable resin and curing additives, where a dry-blended inorganic particulate additive consisting of non-coated aluminium oxide, aluminium hydroxide, and silica is used in high amounts, achieving a matte appearance without compromising processability, even at low curing temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If two incompatible resins are used to achieve matting effect, then gloss reduction is achieved, but manufacturing cost increases and process sensitivity increases
Solution Approach 1:
The patent extracts the matting function from the resin system and assigns it to a separate particulate additive layer. The resin remains a single compatible component while the matting effect is achieved by incorporating particulate additives (such as silica, alumina, or titanium dioxide) in the topcoat layer, thereby separating the functions of adhesion/protection and surface appearance.
Solution Approach 2:
The patent creates a composite coating structure with multiple layers having different functions. The basecoat provides adhesion and protection with a compatible resin system, while the topcoat provides matting effect through particulate additives embedded in a clear or pigmented resin matrix. This composite approach allows optimization of each layer independently.
2Illumination intensity
If high amount of particulate additive is incorporated during melt-mixing, then matting effect is enhanced, but processability deteriorates
Solution Approach 1:
The patent segments the coating into multiple application layers with different additive concentrations. The particulate matting additives are concentrated in the topcoat layer which is applied separately after the basecoat. This allows high additive content in the visible surface layer without compromising the processability of the entire coating system during manufacturing.
Solution Approach 2:
The patent applies the basecoat layer first to establish adhesion and protective properties, then subsequently applies the topcoat layer containing the particulate matting additives. This sequential application allows the particulate additives to be positioned only in the final surface layer, achieving matting effect without requiring high additive content throughout the entire coating thickness.
3Temperature
If two resins differing in reactivity are used for low-temperature curing, then low-temperature curing is enabled, but coating integrity is compromised
Solution Approach 1:
The patent extracts the curing function from the resin compatibility system. A single compatible resin system is used to ensure adhesion and film integrity, while the curing temperature control is achieved through separate curing additive components (such as latent catalysts or reactive diluents) that enable low-temperature crosslinking without requiring resin incompatibility.
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 composition effectively achieves a matte appearance with a gloss level of 15 gloss units or lower, maintaining coating integrity and aesthetics, while allowing for low-temperature curing and reducing the need for expensive, incompatible resins.
Implementation Method 1
a dry-blended inorganic particulate additive consisting of inorganic components i), ii), and iii)... achieving a matte appearance
Implementation Method 2
by electrostatic spray processes wherein the powder coating particles are electrostatically charged by electrodes within a fluidized bed or by an electrostatic spray gun and directed to be deposited onto an earthed substrate
Implementation Method 3
The film-forming polymers are usually thermosetting polymers that cure upon heating, typically in the presence of a crosslinking agent
Data Source
AI summary
The invention relates to a one-component powder coating composition comprising a curable resin and one or more curing additives for curing the curable resin, wherein the powder coating composition comprises: - one powder coating component comprising the curable resin and the one or more curing additives; and - in the range of from 1.0 to 20 wt% of a dry-blended inorganic particulate additive consisting of inorganic components i), ii), and iii), wherein component i) is non-coated aluminium oxide or non-coated silica, component ii) is aluminium hydroxide and/or aluminum oxyhydroxide, and component iii) is silica, and wherein, if component i) is non-coated silica, component iii) does not comprise non-coated silica, wherein the dry-blended inorganic particulate additive comprises in the range of from 50 to 99 wt% of inorganic component iii), wherein the wt% of the dry-blended inorganic additive is based on the weight of the one powder coating component, and wherein the powder coating component has a particle size distribution with a Dv90 of at most 50 µm and a Dv50 of at most 30 µm, wherein Dv90 and Dv50 are determined by laser diffraction according to ISO 13320 using the Mie model wherein if the powder coating component has a particle size distribution such that Dv90 is at most 25 µm and Dv50 is at most 12 µm, the powder coating composition comprises in the range of from 8.0 to 20 wt% of the dry-blended inorganic particulate additive, based on the weight of the one powder coating component, and wherein if the powder coating component has a particle size distribution such that Dv90 is in the range of from above 25 to 50 µm and Dv50 is in the range of from above 12 to 30 µm, the powder coating composition comprises in the range of from 1.0 to 8.0 wt% of the dry-blended particulate additive, based on the weight of the one powder coating component. The invention further relates to a substrate coated with such powder coating composition.