Foamed Polyurethane Steering Wheel Coating Without Topcoat Discoloration
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Solution Overview
Problem
Foamed polyurethane coatings for steering wheels suffer from low light resistance and require a coating film to prevent discoloration and conceal pores, which is labor-intensive and costly.
Innovation Solution
A steering wheel with a foamed polyurethane coating containing benzotriazole ultraviolet absorber and hindered amine photostabilizer, forming an integral skin foam with a non-foamed surface and high-density skin layer, eliminating the need for a separate coating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyurethane coating is used for the steering wheel, then high durability and wear resistance are achieved, but light resistance deteriorates causing discoloration due to ultraviolet degradation
Solution Approach 1:
The patent combines polyurethane material with ultraviolet absorbers and photostabilizers to create a composite coating material that simultaneously provides wear resistance and ultraviolet protection. This composite approach allows the single-layer foam to deliver both mechanical durability and light resistance without requiring separate coating layers.
Solution Approach 2:
The patent modifies the chemical composition parameters of the polyurethane coating by incorporating specific amounts of ultraviolet absorbers (0.5-5 parts by mass) and photostabilizers (0.5-5 parts by mass) relative to polyol. These parameter changes enable the coating to resist ultraviolet degradation while maintaining its inherent wear resistance properties.
2Object-affected harmful factors
If a coating film is formed on the surface of the foamed polyurethane coating to prevent discoloration and conceal pores, then light resistance and appearance are improved, but labor, time, and cost increase
Solution Approach 1:
The patent merges the protective function (ultraviolet resistance) and cosmetic function (pore concealment) into the foamed polyurethane coating itself by incorporating ultraviolet absorbers and photostabilizers. This eliminates the need for a separate coating film, combining multiple functions into a single material system and simplifying the manufacturing process.
Solution Approach 2:
The patent extracts the protective and cosmetic functions from the separate coating film and integrates them directly into the foamed polyurethane coating material through the addition of ultraviolet absorbers and photostabilizers. This extraction eliminates the need for the additional coating layer and its associated manufacturing steps.
3Productivity
If the in-mold coating method is used to form a coating film, then post-molding coating labor and time are reduced, but the process of uniformly applying coating material onto the cavity surface before molding requires labor, time, and cost
Solution Approach 1:
The patent incorporates ultraviolet absorbers and photostabilizers into the polyurethane material before molding, performing the protective function preparation in advance during material formulation rather than during or after the molding process. This preliminary incorporation eliminates the need for pre-molding coating application and subsequent burr removal operations.
4Manufacturing precision
If coating burrs are removed from the mating surfaces of the die through finishing processes, then product quality is improved, but labor, time, and cost increase
Solution Approach 1:
The patent extracts the source of coating burrs (the separate coating material applied to the die cavity) by eliminating the coating film formation step entirely. By incorporating ultraviolet absorbers and photostabilizers into the foamable polyurethane material itself, there is no separate coating material to create burrs, thus eliminating the need for burr removal finishing processes.
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 coating achieves improved light resistance and wear resistance with reduced labor and costs by incorporating ultraviolet absorbers and photostabilizers at high density in the skin layer, eliminating the need for a separate coating film.
Implementation Method 1
the foamed polyurethane coating is formed by foam molding of a polyurethane material containing 91 parts by mass of a base polyol, 10 to 25 parts by mass of a pigment, 1 to 3 parts by mass of a benzotriazole ultraviolet absorber, 0.8 to 2.5 parts by mass of a hindered amine photostabilizer
Implementation Method 2
the skin layer has a non-foamed surface and a thickness of 50 μm or more, wherein a degree of foaming increases with an increase in depth from the surface
Data Source
AI summary
A steering wheel includes a core and a foamed polyurethane coating that covers a ring section of the core. The foamed polyurethane coating is formed by foam molding of a polyurethane material containing 91 parts by mass of a base polyol, 10 to 25 parts by mass of a pigment, 1 to 3 parts by mass of a benzotriazole ultraviolet absorber, 0.8 to 2.5 parts by mass of a hindered amine photostabilizer, and a polyisocyanate. A total amount of the ultraviolet absorber and the photostabilizer is 2.7 parts by mass or more. The foamed polyurethane coating is in the form of an integral skin foam including a highly foamed core foam and a lowly foamed skin layer. The surface of the skin layer is not provided with a coating film formed from a coating material, and serves as a product surface that assumes a color of the pigment.