Aqueous Polyurethane Dispersion with Durable Low Gloss
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Solution Overview
Problem
Existing polyurethane dispersions used for coatings tend to lose their matte aspect when exposed to heat and light, and the addition of matting particles can destabilize polymer compositions and pose health risks due to the use of silica particles.
Innovation Solution
Aqueous polyurethane dispersions are synthesized using polycarbonate diols with a limited amount of other diols, stabilized with an acrylic thickener and a surfactant having a specific HLB, and chain extended in water without organic solvents, achieving a durable low-gloss finish without external matting additives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If matting particles (silica or polymer) are added to polyurethane dispersions to increase matt effect, then the gloss is reduced, but the composition becomes destabilized and the film becomes more brittle
Solution Approach 1:
The invention extracts and eliminates the need for external matting particles by incorporating matting functionality directly into the polyurethane polymer structure itself through specific diol components, thereby removing the destabilizing element while maintaining the desired low gloss effect
Solution Approach 2:
The invention merges the matting function with the polyurethane polymer structure by incorporating specific diol components (such as poly(tetramethylene glycol) or polyester diols) that inherently provide both structural integrity and matting properties, creating a unified material that achieves low gloss without external additives
2Illumination intensity
If heterogeneous matting particles are added to achieve low gloss, then the matt effect is improved, but separation of materials occurs during application causing heterogeneity of optical effect
Solution Approach 1:
The invention applies local quality by making the matting property an intrinsic characteristic of the polyurethane polymer chains themselves through specific diol incorporation, ensuring uniform distribution and consistent optical effect throughout the entire coating without localized variations
Solution Approach 2:
The invention achieves homogeneity by integrating matting functionality into the polymer structure at the molecular level, ensuring that the low gloss effect is uniformly distributed throughout the entire coating composition rather than being present as separate heterogeneous particles
3Illumination intensity
If amorphous or crystalline silica is used to increase matt effect, then the gloss is reduced, but health risks are created due to pulmonary disease risks from fine particle exposure
Solution Approach 1:
The invention extracts and removes hazardous silica particles from the formulation entirely, replacing them with safe polymeric matting agents that provide the same low gloss effect without any health risks associated with fine particle inhalation
Solution Approach 2:
The invention converts the harmful silica particles into beneficial polymeric matting agents that provide the desired optical effect while eliminating health risks, effectively transforming a hazardous approach into a safe and effective solution
4Illumination intensity
If polyglycol ether polyurethanes are used to achieve low gloss and soft touch, then the initial matt aspect is obtained, but the matt aspect is lost when exposed to ambient heat and light
Solution Approach 1:
The invention changes the chemical parameters of the polyurethane structure by incorporating specific diol components (such as poly(tetramethylene glycol) or polyester diols) that provide heat and light stability, thereby maintaining the low gloss effect under prolonged environmental exposure
Solution Approach 2:
The invention creates a composite polyurethane structure combining different diol components with specific properties that confer both matting capability and environmental stability, resulting in a durable low gloss coating that maintains its appearance under heat and light exposure
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 process results in stable, low-gloss coatings that maintain their matte appearance under heat and light exposure, eliminating the need for hazardous silica particles and ensuring a homogeneous, re-dispersible dispersion.
Implementation Method 1
stabilizing the dispersion with an acrylic thickener and a surfactant having HLB between 10 and 20
Implementation Method 2
stabilizing the dispersion with an acrylic thickener and a surfactant having HLB between 10 and 20
Implementation Method 3
by using polycarbonate diols in the synthesis of the polyurethane... that, without the addition of matt additives, is able to give films with durable low gloss (matt aspect)
Implementation Method 4
The resistance of matt to light exposure is particularly desirable in the field of leather (artificial or natural) for automotive interiors
Implementation Method 5
the prepolymer is chain extended in water in the presence of from 0.1 to 2% by weight, preferably from 0.3% to 1% by weight of a surfactant having HLB from 10 to 20
Data Source
AI summary
Process for the preparation of aqueous polyurethane dispersions, containing from 20 to 50% by weight of an anionic polyurethane having a mean particle size from 1 to 15 micron and providing films with durable low gloss aspect.