Polyurethane Elastomer for Paper Mill Press Roll
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Solution Overview
Problem
Polyurethane elastomers used in paper mill equipment, such as press rolls and belts, face issues with thermo-oxidative decomposition and low chemical resistance at high temperatures, leading to reduced part life and limited working temperature due to the use of Poly(tetramethylene) ether glycol (PTMEG), which is prone to melting or debonding under high moisture and elevated temperature conditions.
Innovation Solution
Development of polyurethane elastomers using a mixed composition that includes a urethane prepolymer obtained by reacting a polyisocyanate compound with a polycarbonate diol compound having a number average molecular weight of at least 1500 g/mol, and a curing agent that includes an amine compound and the same polycarbonate diol, resulting in a polyurethane layer with a hysteresis value of less than 70% and a permanent set of less than 30%, enhancing resistance to high temperatures and moisture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If PTMEG based polyurethane elastomers are used in paper mill equipment, then load bearing capability and abrasion resistance are improved, but resistance to high temperature and moisture deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the polyurethane elastomer by replacing PTMEG with polycarbonate diol compounds having specific molecular weights (at least 1500 g/mol). This parameter change transforms the material's thermal and chemical stability while preserving its mechanical properties, directly resolving the contradiction between strength and high-temperature reliability.
Solution Approach 2:
The invention creates a composite polyurethane system combining polycarbonate diol compounds with specific isocyanates and curing agents. This composite approach leverages the superior thermal stability of polycarbonate structures while maintaining the elastomeric properties needed for load bearing, thus simultaneously achieving both strength and high-temperature resistance.
2Strength
If PTMEG based polyurethane elastomers are used in paper mill equipment, then abrasion resistance is improved, but part life under high temperature conditions deteriorates
Solution Approach 1:
The invention modifies the chemical structure parameters by substituting PTMEG with high molecular weight polycarbonate diol compounds (at least 1500 g/mol). This change preserves the wear-resistant surface properties while fundamentally improving thermal stability, thereby extending part life under high-temperature operating conditions without sacrificing abrasion resistance.
Solution Approach 2:
The patent addresses the short service life issue by creating a durable material that resists thermo-oxidative decomposition. The polycarbonate-based formulation significantly extends component lifespan compared to PTMEG alternatives, reducing the frequency of replacement and maintenance interventions.
3Strength
If PTMEG based polyurethane elastomers are used, then mechanical properties are improved, but working temperature range deteriorates
Solution Approach 1:
The invention fundamentally changes the chemical composition from PTMEG to polycarbonate diol compounds with molecular weights of at least 1500 g/mol. This compositional parameter change raises the decomposition temperature and improves thermal stability, thereby expanding the working temperature range while preserving essential mechanical properties through optimized curing formulations.
Solution Approach 2:
The patent applies local quality by using specific high molecular weight polycarbonate diol compounds (at least 1500 g/mol) in critical regions of the polyurethane structure that require thermal stability. This targeted material selection maintains mechanical performance in load-bearing areas while providing heat resistance in high-temperature exposure zones.
4Reliability
If polycarbonate diol compound with high molecular weight is used, then resistance to hydrolysis and chemical resistance are improved, but hysteresis increases
Solution Approach 1:
The invention carefully selects polycarbonate diol compounds with molecular weights of at least 1500 g/mol, representing an optimized parameter range. This specific molecular weight threshold provides sufficient chain length for hydrolysis resistance while controlling the hysteresis effect, achieving a balance between chemical stability and energy loss characteristics.
Solution Approach 2:
The patent utilizes the molecular structure characteristics of high molecular weight polycarbonate diols to create a network structure that resists hydrolytic attack. The extended polymer chains and crosslinked architecture formed by curing agents create a dense, hydrolysis-resistant matrix that minimizes water penetration and chemical degradation, while the controlled molecular weight keeps hysteresis within acceptable limits.
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 solution provides paper mill equipment with improved resistance to high temperatures and moisture, extending the life of components and maintaining mechanical properties, as evidenced by reduced hysteresis and permanent set, thereby enhancing the durability and performance of paper machine press rolls, belts, and acid pickling rollers.
Implementation Method 1
reacting at least a polyisocyanate compound (a) with at least a polycarbonate diol compound (b)
Implementation Method 2
curing agent (B) includes at least an amine compound and at least the polycarbonate diol compound (b)
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Embodiments of the invention provide for paper mill equipment that can better withstand the conditions of a paper mill. Embodiments encompass paper mill equipment that incorporate a polyurethane layer having a hysteresis value of less than 70% and a permanent set of less than 30%. The polyurethane layer includes a polyurethane produced by curing a mixed composition. The mixed composition includes at least a urethane prepolymer (A) and at least a curing agent (B) having an active hydrogen group (H). The urethane prepolymer (A) has at least one terminal isocyanate group and is obtained by reacting at least a polyisocyanate compound (a) with at least a polycarbonate diol compound (b) having a number average molecular weight of at least 1500 g/mol. The curing agent (B) includes at least an amine compound. The elastomer compositions are also useful to coat the acid pickling roller in the steel industry.