Liquid Rosin Ester Adhesive Odor and Low-Temperature Tack
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Solution Overview
Problem
Conventional adhesive compositions, particularly those using rosin-based tackifiers, suffer from odor issues, decreased tack at low temperatures, and instability under heat and light, making them unsuitable for hygiene products like disposable diapers and sanitary napkins.
Innovation Solution
A liquid rosin ester compound with specific properties, such as a Gardner color of 1 or less, a glass transition temperature of −20° C. or less, and a high degree of esterification, is used to create an adhesive composition that is odorless, colorless, and maintains excellent adhesion and stability under heat and light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional rosin-based tackifiers are used to improve adhesive strength, then adhesive strength is improved, but the adhesive develops strong odor and deteriorates under heat and light
Solution Approach 1:
The patent applies parameter changes by modifying the chemical structure of the rosin-based compound through hydrogenation and esterification. The degree of hydrogenation is controlled at 5-50% and degree of esterification at 80-95%, which transforms the molecular properties to reduce odor while maintaining adhesive strength and improving stability under heat and light.
Solution Approach 2:
The patent creates a composite material system by combining partially hydrogenated rosin with a polyol compound. This composite approach allows the synergistic effects of both components, where the hydrogenated rosin provides adhesive strength and the polyol component contributes to odor reduction and improved stability.
2Strength
If rosin-based compounds are used as tackifiers, then adhesive strength is improved, but the adhesive hardens at low temperatures causing zipping and reduced tack
Solution Approach 1:
The patent modifies the glass transition temperature parameter by controlling the degree of hydrogenation (5-50%) and esterification (80-95%). These parameter changes adjust the molecular flexibility and free volume, preventing the adhesive from hardening at low temperatures while maintaining adequate adhesive strength.
Solution Approach 2:
The patent introduces local quality by creating regions of different molecular mobility through partial hydrogenation. The non-hydrogenated portions maintain flexibility for low-temperature performance, while hydrogenated portions provide structural integrity and adhesive strength.
3Strength
If conventional liquid rosin-based tackifier resin is used, then some adhesion performance is achieved, but the adhesive shows insufficient adhesion at low temperatures and lacks stability to heat and light
Solution Approach 1:
The patent systematically changes the chemical parameters by controlling hydrogenation degree (5-50%) and esterification degree (80-95%). These parameter adjustments simultaneously improve adhesion performance at low temperatures and enhance stability to heat and light, resolving the reliability issue.
Solution Approach 2:
The patent applies preliminary action by pre-hydrogenating and pre-esterifying the rosin-based compound before final adhesive formulation. This preliminary chemical modification stabilizes the molecule against further degradation from heat and light exposure during subsequent use.
4Strength
If rosin-based compounds are used to improve adhesive strength, then adhesive strength is improved, but the adhesive develops strong odor that spreads during use
Solution Approach 1:
The patent changes the chemical parameters by implementing partial hydrogenation (5-50%) and esterification (80-95%). These parameter changes modify the volatile components responsible for odor while preserving the adhesive strength properties of the rosin-based compound.
Solution Approach 2:
The patent converts the harmful volatile components that cause odor into beneficial stable ester groups through esterification reaction. The reaction transforms odorous carboxylic acid groups into non-volatile ester groups, converting the harmful property into a beneficial stability property.
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 adhesive composition is substantially odorless, exhibits good tack at low temperatures, and provides long-lasting heat and light resistance, making it suitable for use in hygiene materials.
Implementation Method 1
a glass transition temperature of −20° C. or less
Implementation Method 2
rosin-based compounds are structurally susceptible to oxidative degradation due to heat or light, leading to deterioration of the adhesives
Data Source
AI summary
An object of the present invention is to provide an adhesive composition that is substantially odorless and has an extremely good color and excellent adhesive properties or tack at low temperatures of about 5° C. and in which deterioration over time caused by heat or light is suppressed. The present invention relates to an adhesive composition comprising a liquid rosin ester compound, the liquid rosin ester compound being obtained by reacting a rosin compound with a C1-10 monohydric alcohol compound and having a Gardner color of 1 or less, a glass transition temperature of −20° C. or less, a degree of esterification of 93 wt % or more, and a ratio (Y′/Y) of the total area of peaks in 16- to 22-min retention time region (Y′) to the total area of all the peaks (Y) measured by gas chromatography under the following conditions of 200 ppm or less.