Rosin Ester Hot-Melt Adhesive Low-Temperature Application
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Solution Overview
Problem
Current hot-melt adhesives require high temperatures for application, posing safety risks and energy inefficiencies, and existing rosin esters may compromise compatibility and stability, particularly at lower application temperatures.
Innovation Solution
Compositions comprising low molecular weight ethylene polymers and rosin esters with specific properties, such as low hydroxyl and acid numbers, and controlled molecular weights, which enhance viscosity stability and compatibility at elevated temperatures without the need for additional reaction steps like Diels-Alder or Ene reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high temperature application is used to ensure complete melting and satisfactory viscosity, then adhesive performance is improved, but safety risks and energy consumption increase
Solution Approach 1:
The patent changes the molecular weight parameter of the rosin ester from high to low (specifically 500-2000 g/mol), which fundamentally alters the melting and flow characteristics of the adhesive system, enabling effective application at lower temperatures while maintaining adhesive performance
Solution Approach 2:
The patent creates a composite adhesive system combining low molecular weight ethylene polymers (high MI values) with low molecular weight rosin esters, where the synergistic interaction between components enables low-temperature application with maintained reliability
2Reliability
If high molecular weight rosin esters are used to improve heat stress resistance, then adhesive properties are enhanced, but compatibility and stability are compromised
Solution Approach 1:
The patent inverts the molecular weight parameter of rosin esters from high (conventional) to low (500-2000 g/mol), which unexpectedly improves both heat stress resistance and compatibility/stability simultaneously by reducing molecular complexity and enhancing uniform distribution
Solution Approach 2:
The patent uses low molecular weight rosin esters in optimized quantities (5-50 wt%) to achieve sufficient heat stress resistance without the negative effects of high molecular weight variants, applying just enough of the beneficial property without excess
3Temperature
If low molecular weight polymers with high melt flow index are used to enable low temperature application, then application temperature is reduced, but adhesive properties such as toughness and heat resistance are lost
Solution Approach 1:
The patent formulates a composite system where low molecular weight ethylene polymers (providing low-temperature processability) are combined with low molecular weight rosin esters (providing heat stress resistance and toughness), achieving both low application temperature and maintained adhesive strength
Solution Approach 2:
The patent changes the molecular weight parameter of the rosin ester component to low values (500-2000 g/mol), which fundamentally alters the thermal and mechanical properties of the adhesive system, enabling it to maintain strength at low application temperatures
Data Source
AI summary
Disclosed are compositions which include an ethylene polymer derived from at least one polar monomer with one or more ester groups, and a rosin ester. The rosin ester can have a low hydroxyl number (e.g., a hydroxyl number seven or less), a low acid number (e.g., an acid number of ten or less), a relatively low PAN number (e.g., a PAN number less than twenty-five), a relatively high third moment or third power average molecular weight (Mz), (e.g., an Mz value in between 2500 and 12000 g/mol), a low sulfur content (e.g., a sulfur content lower than 600 ppm prior to antioxidant addition) or combinations thereof. The compositions can exhibit a high heat stress resistance (e.g., a heat stress pass temperature value higher than 52° C. or in between 48° C. and 60° C.) and/or improved viscosity stability and/or color stability upon thermal aging and/or improved compatibility.