Multilayer Polyurethane Surfacing Film with Crosslinked Clear Coat
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Solution Overview
Problem
Conventional surfacing films for paint protection and paint replacement applications have limitations in scratch resistance, self-healing properties, and adhesive peel strength, and often emit undesirable odors due to residual solvents, which affect user experience and performance.
Innovation Solution
The development of a surfacing film with a multilayer construction using a copolymerized acrylic-styrene polyol to increase crosslink density, combined with a dual-layered clear coat composition to mitigate odor issues, and a process involving a first and second crosslinkable polyurethane clear coat layer with a thermoplastic polyurethane layer and adhesive layer for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional surfacing films are used, then basic paint protection is provided, but scratch resistance and self-healing properties are limited
Solution Approach 1:
The patent modifies the chemical composition parameters by using a copolymerized acrylic-styrene polyol with specific hydroxyl group content, increasing crosslink density to achieve superior scratch resistance while maintaining self-healing properties. The clear coat layers are cured to specific degrees (first layer partially cured, second layer at least partially cured) to optimize both hardness and flexibility for scratch resistance and self-healing.
Solution Approach 2:
The patent creates a composite multilayer structure combining thermoplastic polyurethane bulk layer with crosslinked polyurethane clear coat layers. This composite construction integrates the flexibility and durability of thermoplastic polyurethane with the protective and self-healing properties of crosslinked clear coats, achieving both superior scratch resistance and reliable self-healing properties.
2Strength
If conventional adhesive formulations are used, then basic adhesion is achieved, but adhesive peel strength and stain resistance have significant margin for improvement
Solution Approach 1:
The patent changes the adhesive formulation parameters by using a thermoplastic polyurethane adhesive layer with specific composition and crosslink density. The adhesive is applied at controlled thickness and cured to achieve optimal balance between peel strength and stain resistance. The copolymerized acrylic-styrene polyol in the clear coat also contributes to improved adhesive performance through enhanced crosslinking.
3Ease of manufacture
If single-layer clear coat construction is used, then simpler manufacturing is achieved, but odor issues from residual solvent cannot be mitigated
Solution Approach 1:
The patent divides the clear coat into two separate layers with different functions. The first clear coat layer is applied and partially cured to provide initial protection and serve as a base for the second layer. The second clear coat layer is then applied and at least partially cured to provide additional protection and trap residual solvents, thereby mitigating odor issues. This segmentation allows each layer to be optimized for specific purposes while managing solvent emissions.
4Strength
If conventional crosslink density is used, then material flexibility is maintained, but scratch resistance and self-healing properties are limited
Solution Approach 1:
The patent systematically changes the crosslink density parameter by using a copolymerized acrylic-styrene polyol with controlled hydroxyl group content and reacting it with isocyanate in specific ratios. The first clear coat layer is cured to a specific degree (partial cure) while the second layer is at least partially cured, creating an optimized crosslink density gradient that enhances scratch resistance and self-healing properties while maintaining necessary flexibility.
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 resulting film exhibits improved stain resistance, high initial and aged adhesive peel strength, superior scratch resistance, and self-healing properties while minimizing solvent odor, with increased throughput and reduced factory costs.
Implementation Method 1
a copolymerized acrylic-styrene polyol containing a multiplicity of hydroxyl groups. This enables crosslink density to be dramatically increased relative to those of prior film compositions
Implementation Method 2
disposing a first curable polyurethane clear coat composition on a first release liner, the first curable polyurethane clear coat composition comprising a copolymer of styrene and hydroxyl-containing (meth)acrylate; only partially curing the first curable polyurethane clear coat composition to provide a first clear coat layer
Data Source
AI summary
Provided is a surfacing film that includes a plurality of layers. The layers include a first clear coat layer made from a crosslinked polyurethane that is a reaction product of a reactive mixture including an isocyanate and a polyol containing a styrene repeat unit and a hydroxyl-containing (meth)acrylate repeat unit. The surfacing film further includes a bulk layer made from a thermoplastic polyurethane and an adhesive layer. Optionally, the surfacing film includes second clear coat layer, which can be made from a polyurethane that is at least partially crosslinked. The resulting surfacing film can display high stain resistance, high peel strength, superior scratch resistance and self-healing properties.