Polyurethane Coating for Recycled Rubber Color and UV Durability
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Solution Overview
Problem
Current methods for colorizing recycled tire rubber products result in uneven color distribution, poor adhesion, and susceptibility to fading, delamination, and wear, failing to withstand environmental factors and flexion.
Innovation Solution
A method involving a base layer of aromatic polyurethane coating followed by a top coat of water-based aliphatic polyurethane, optionally colorized, to encapsulate recycled tire rubber, using specific ratios and surface preparation to enhance adhesion and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If iron oxide powder or colored liquid urethane is used to coat crumb rubber particles, then homogeneous color application is achieved, but the coating is short-lived and susceptible to UV fading and discoloration
Solution Approach 1:
The patent uses a clear polymeric coating as an intermediary layer that encapsulates the iron oxide colorant and protects it from UV exposure. This mediator layer allows the colorant to be applied homogeneously while shielding it from environmental degradation, resolving the contradiction between color uniformity and UV stability
Solution Approach 2:
The invention creates a composite coating system combining iron oxide pigment with a polymeric binder and clear protective coating. This composite structure provides both homogeneous color distribution from the iron oxide and UV resistance from the polymeric matrix, simultaneously achieving both desired properties
2Manufacturing precision
If iron oxide coating is applied to crumb rubber, then color coverage is achieved, but the coating deteriorates rapidly under foot traffic and vehicle use
Solution Approach 1:
The patent applies a flexible polymeric coating film that encapsulates the iron oxide colorant. This flexible shell conforms to the substrate and provides mechanical protection against wear from foot traffic and vehicle use, while maintaining the color coverage property
Solution Approach 2:
The composite coating structure combines iron oxide pigment for color coverage with a polymeric matrix that provides wear resistance. The composite nature allows both coloration and mechanical durability to be achieved simultaneously
3Manufacturing precision
If topical coating material is applied to molded rubber parts, then colorization is achieved, but the coating delaminates due to mold release agents
Solution Approach 1:
The patent applies a preliminary clear polymeric coating to the molded rubber part before applying the iron oxide colorant. This preliminary coating creates a clean, adhesive surface that is free from mold release agents, ensuring subsequent colorant adhesion while maintaining colorization
4Manufacturing precision
If EPDM or SBR sheet is overlaid on recycled tire rubber, then solid color is achieved, but the material is expensive and does not encapsulate the entire part
Solution Approach 1:
The patent changes the form of the colorant from thick rubber sheets to a sprayable or dipable polymeric coating solution. This parameter change allows uniform encapsulation of the entire part at much lower material cost while achieving solid color appearance
Solution Approach 2:
The patent uses a thin polymeric film coating that can be uniformly applied over the entire surface of the molded part. This thin film provides complete encapsulation at lower cost compared to thick rubber sheet overlays, achieving solid color with better cost-effectiveness
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 method provides homogeneous color coverage, improved adhesion, and resistance to UV exposure, weathering, abrasion, and flexion, preventing chemical leaching and enhancing the appearance of recycled tire products.
Implementation Method 1
A method for coating recycled rubber includes an application of a base layer of an aromatic polyurethane coating. This adhesive pre-coat is applied to overcome the concerns of mold release contamination.
Implementation Method 2
The method provides homogeneous color coverage, improved adhesion, and resistance to UV exposure, weathering, abrasion, and flexion
Implementation Method 3
The architectural community is keenly aware of the short life span of these materials and infrequently specify iron oxide or urethane rubber coated products... resistance to UV exposure, weathering, abrasion, and flexion
Data Source
AI summary
Disclosed is a process for coating a product made of one or more of: rubber, recycled rubber, plastic, or recycled plastic. The product is coated with a base layer of an aromatic polyurethane mixture and then a top layer of a water-based aliphatic polyurethane. The top coating may include a colorant. The method provides an economical way to produce a recycled rubber product that has a uniform color.