Polyisocyanate Paint Composition for Scratch and Impact Resistance
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Solution Overview
Problem
Conventional paint compositions for clear paint films face challenges in achieving both excellent scratch resistance and impact resistance, with existing solutions either compromising on hardness or elasticity, leading to issues such as cracking or scraping when exposed to external forces like car washing or debris impacts.
Innovation Solution
A paint composition comprising a polyisocyanate prepolymer derived from specific (meth)acrylate compounds with an isocyanate group and a polyol, where the average functional group equivalent weight is within a specific range, allowing for controlled crosslinking density and hardness, along with elastic properties through hydrogen bonds, to form multilayer paint films with enhanced scratch and impact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the crosslinking density of crosslinkable resins is increased to improve scratch resistance, then the hardness of the paint film increases, but the adhesion decreases and cracks occur due to cure shrinkage strain
Solution Approach 1:
The patent changes the chemical composition parameters by introducing a specific polyisocyanate component with NCO groups that reacts with hydroxyl groups in the resin. This chemical parameter change enables crosslinking that improves scratch resistance while the controlled formulation maintains adhesion by balancing the crosslinking density with appropriate resin selection.
2Strength
If the hardness of the paint film is increased to withstand friction at high external force, then the scratch resistance improves, but the impact resistance deteriorates as the film becomes too rigid and cracks or scrapes off
Solution Approach 1:
The patent creates a composite paint film system by combining multiple resin components including polyisocyanate, acrylic resin, and polysiloxane resin. This composite formulation achieves a balance between hardness and elasticity, allowing the film to resist scratches while maintaining flexibility to absorb impact forces without cracking or scraping off.
3Force
If polycaprolactone is introduced to increase elastic properties and scratch resistance, then the impact resistance improves, but the hardness decreases making the film prone to scraping off under high friction
Solution Approach 1:
The patent merges multiple resin systems with complementary properties: polyisocyanate for crosslinking and hardness, acrylic resin for film formation and flexibility, and polysiloxane for elasticity and impact resistance. This combination allows the paint film to simultaneously achieve high hardness for scratch resistance and high elasticity for impact resistance, resolving the contradiction between these 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 paint composition achieves paint films with superior scratch resistance and impact resistance, capable of withstanding high external forces without cracking or removal, while maintaining high solidifiability and reducing solvent usage.
Implementation Method 1
increasing the crosslinking density of crosslinkable resins that form the paint films
Implementation Method 2
elastic properties through hydrogen bonds
Data Source
AI summary
The invention has an object of providing paint compositions showing excellent performances in both scratch resistance and impact resistance, and processes for forming multilayer paint films using the paint composition. The invention has another object of providing paint compositions suitably used as clear paints for finish painting automobiles and the like, and highly solidifiable paint compositions. A paint composition according to the invention includes a polyisocyanate prepolymer (A) including a monomer unit of Formula (1) below and a polyol (B), and has an average functional group equivalent weight of 160 to 400 g/eq. A process for forming multilayer paint films involves the paint composition. wherein R1 is a hydrogen atom or a methyl group; n is an integer of 0 or 1; when n = 0, 1 = 0, p = 1 and m is an integer of 1 to 8; and when n = 1, m = 2, 1 = 2 and p is an integer of 1 to 4.