Polyurethane Protective Sheet Bonding for Abrasion Resistance
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Solution Overview
Problem
Conventional protective coatings and sheets, such as gel coats, often fail to provide adequate abrasion resistance, impact resistance, and durability due to their thinness, hardness, and tendency to crack, leading to water penetration and structural damage, while also decreasing processing efficiency and limiting design flexibility.
Innovation Solution
A protective sheet integrally bonded to the article, made of extensible polyurethane-based layers, which provides enhanced chip resistance and is visually clear, eliminating the need for additional coatings and layers, and can be applied using in-mold processing techniques for improved bonding and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gel coats are applied to protect exterior surfaces, then aesthetics and basic protection are improved, but abrasion resistance and impact resistance deteriorate due to thinness and hardness
Solution Approach 1:
The patent uses composite materials by combining a polyurethane sheet with an adhesive layer and the substrate article. The polyurethane sheet provides superior abrasion and impact resistance while the adhesive layer ensures strong bonding, creating a composite structure that overcomes the limitations of conventional gel coats.
Solution Approach 2:
The patent changes the thickness parameter of the protective layer from the thin gel coat application to a thicker polyurethane sheet (typically 0.002 to 0.045 inches), which provides substantially improved abrasion and impact resistance while maintaining aesthetic properties.
2Reliability
If gel coats are applied post-molding, then protective performance is improved, but processing efficiency deteriorates due to additional labor and manufacturing time
Solution Approach 1:
The polyurethane sheet is prepared and positioned on the mold cavity before the article is molded. This preliminary action allows the protective sheet to be integrated into the molding process itself, eliminating post-molding application steps and significantly improving processing efficiency.
Solution Approach 2:
The patent merges the protective sheet application with the molding process by placing the sheet on the mold cavity before injection or compression molding. This combines two separate operations (protective layer application and article formation) into a single integrated process step.
3Productivity
If gel coats are applied in-mold, then processing efficiency is improved, but cure time increases significantly before actual molding can begin
Solution Approach 1:
The patent extracts the curing step from the protective layer application process. By using a pre-formed polyurethane sheet that is already cured, the method eliminates the several hours of cure time required for gel coats, allowing immediate molding without waiting for the protective layer to cure.
4Area of stationary object
If protective sheets are applied to surfaces with complex shapes, then coverage is improved, but application difficulty increases due to extensibility requirements
Solution Approach 1:
The patent changes the extensibility parameter of the protective material by using a polyurethane sheet with specific elastic properties. The sheet can be stretched to 150-400% of its original size, allowing it to conform to complex three-dimensional mold cavity shapes while maintaining ease of application through simple stretching rather than complex manipulation.
Data Source
Figure 1
AI summary
Methods of the invention include those for applying protective sheets to articles. According to these methods and resulting articles, a protective sheet is applied to at least a portion of an exterior surface where protection is desired on an article. At least one portion of at least one exterior surface of the article to be protected can be integrally formed in the presence of the protective sheet. Improved bonding of the protective sheet to the article and improved processing efficiency are advantageously achieved according to the invention.