Press Sleeve Polyurethane Coating Bubble-Free Single Pass
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Solution Overview
Problem
Press sleeves in shoe presses face challenges with stability and service life due to mechanical stress, air bubbles, and manufacturing limitations with existing polyurethane materials, which lead to premature failure.
Innovation Solution
The use of a polycaprolactone-polycarbonate polyol with a crosslinking agent containing a diamine and carbonic acid ester, such as propylene carbonate, results in a prepolymer-crosslinker mixture with lower viscosity and optimal pot life, allowing for bubble-free, thick polymer layers to be produced in a single coating pass, enhancing mechanical and dynamic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If existing polyurethane materials are used for press sleeves, then flexibility can be achieved, but stability and service life are insufficient due to mechanical stress and hydrolysis
Solution Approach 1:
The patent uses a composite material system consisting of polyol, isocyanate, and extender isocyanate in specific ratios to create a polyurethane composition with enhanced stability. The composite nature of this chemical system provides both flexibility and improved resistance to mechanical stress and hydrolysis, resolving the contradiction between flexibility and stability.
Solution Approach 2:
The patent modifies the chemical parameters of the polyurethane system by changing the ratio of polyol to isocyanate components and selecting specific molecular weight ranges. These parameter changes optimize the balance between flexibility and stability, allowing the material to maintain both properties simultaneously under press sleeve operating conditions.
2Productivity
If thicker polymer layers are desired for each coating pass, then manufacturing efficiency improves, but air bubbles form leading to premature failure
Solution Approach 1:
The patent changes the viscosity parameters of the coating composition by adjusting the chemical composition ratios and selecting appropriate molecular weights. This parameter optimization allows thicker layers to be applied without trapping air bubbles, as the modified rheological properties enable proper air release while maintaining coating integrity.
Solution Approach 2:
The patent eliminates the need for reinforcement structures (threads, fabrics) that are prone to failure from air bubbles. By using a disposable-like approach where the polymer layer itself is optimized to be bubble-free through composition control rather than structural reinforcement, the service life is improved without compromising manufacturing efficiency.
3Manufacturing precision
If a second coating pass is carried out to achieve desired thickness, then coating quality improves, but manufacturing time and complexity increase
Solution Approach 1:
The patent optimizes the viscosity and chemical composition parameters to enable single-pass coating at the desired final thickness. By adjusting these parameters, the coating can be applied uniformly in one pass without requiring multiple passes, thereby simplifying the manufacturing process while maintaining coating quality.
Solution Approach 2:
The patent extracts the reinforcement structure (threads, fabrics) from the coating system, relying instead on the optimized polymer composition to provide the necessary structural integrity. This elimination of additional components simplifies the coating process to a single pass while maintaining manufacturing precision through composition control rather than structural complexity.
4Ease of operation
If press sleeves are subjected to strong alternating bending loads during operation, then they can perform their pressing function, but the tendency to break increases especially at entry and exit points
Solution Approach 1:
The patent employs a composite chemical system with specific ratios of polyol, isocyanate, and extender isocyanate that creates a polyurethane material with enhanced toughness and flexibility. This composite material structure allows the press sleeve to withstand strong alternating bending loads during operation without breaking, while maintaining the necessary flexibility to perform the pressing function.
Solution Approach 2:
The patent modifies the molecular weight parameters and chemical composition ratios to optimize the material's resistance to fatigue from alternating bending loads. By selecting specific molecular weight ranges and composition ratios, the press sleeve gains improved durability at stress concentration points (entry and exit) while preserving operational 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
This solution achieves increased stability, longer service life, and improved resistance to hydrolysis and mechanical stress, enabling the production of almost bubble-free press jackets with polymer layers up to 40 mm thick in a single pass, enhancing the operational durability of press sleeves.
Implementation Method 1
the prepolymer being a reaction product of 1,4-phenylene diisocyanate (PPDI) and at least one polyol
Implementation Method 2
a crosslinking agent comprising a diamine and a carbonic acid ester
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a press jacket comprising at least one polymer layer containing a polyurethane or being produced from a polyurethane, wherein the polyurethane is formed from a prepolymer and a cross-linking agent, and the prepolymer is a reaction product of caprolactam and carbonate, such as polycaprolacton polycarbonate-polyol, containing 1,4-phenylene diisocyanate (PPDI) and at least one polyol.