Styrene Block Copolymer Hot Melt Adhesive for Lower-Temperature Processing
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Solution Overview
Problem
Existing hot melt adhesives for absorbent articles have high viscosities that hinder processability and can damage substrates, requiring high application temperatures and excessive energy, while lacking adequate cohesion and adhesive properties.
Innovation Solution
A hot melt adhesive composition comprising 22% to 60% styrene block copolymer and 0.1% to 5% wax with specific viscosity ranges, ensuring good processability and cohesion, using styrene block copolymers with a styrene content of 38% to 70% and a diblock content of 0% to 10%, along with additives like tackifying resin and plasticizer to achieve optimal viscosity and adhesive properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If styrene block copolymers with high styrene content are used to obtain high cohesion, then adhesive strength is improved, but viscosity becomes too high making application difficult and requiring high temperature
Solution Approach 1:
The patent applies parameter changes by precisely controlling the styrene content (38-70%) and diblock content (0-10%) of the styrene block copolymer, along with specifying viscosity ranges at different temperatures, to achieve the optimal balance between cohesion and processability
Solution Approach 2:
The patent uses composite materials by combining styrene block copolymers with specific additives including waxes (0.1-5%), tackifying resins (5-30%), and plasticizers (5-30%), creating a multi-component adhesive system that achieves both high cohesion and good processability
2Ease of operation
If high temperature is used to apply the adhesive, then viscosity is reduced improving flow, but substrate damage occurs and energy consumption increases
Solution Approach 1:
The patent specifies viscosity ranges at different temperatures (≥30,000 mPa.s at 120°C and ≤5,000 mPa.s at 177°C) to define the optimal application temperature window, enabling viscosity control without excessive heating
Solution Approach 2:
The patent introduces waxes with specific congealing points (≥60°C) and needle penetration values (≤2 dmm) as intermediary substances that modify the adhesive's thermal behavior, allowing for lower application temperatures while maintaining proper flow characteristics
3Ease of operation
If high temperature is used to apply the adhesive, then viscosity is reduced improving flow, but energy consumption increases
Solution Approach 1:
The patent defines specific viscosity ranges at different temperatures to optimize the application temperature, reducing energy consumption by avoiding excessive heating while maintaining adequate flow properties
Solution Approach 2:
The patent uses waxes as intermediary substances that modify the temperature-viscosity relationship, enabling the adhesive to achieve proper flow at lower temperatures and thus reducing energy consumption during application
4Ease of operation
If viscosity is reduced for better processability, then application becomes easier, but adhesive strength and cohesion deteriorate
Solution Approach 1:
The patent specifies viscosity ranges at different temperatures to define the optimal processability window, ensuring that viscosity is sufficiently low for application but high enough to maintain adhesive strength
Solution Approach 2:
The patent combines styrene block copolymers with tackifying resins (5-30%) and other additives to create a composite system where the synergistic interaction maintains both processability and adhesive strength
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 composition allows for effective application at lower temperatures, maintaining substrate integrity and cohesion, ensuring the absorbent core remains stable in both dry and wet states, with improved processability and adhesive performance.
Implementation Method 1
obtain high cohesion of the absorbent core by using styrene block copolymers with high contents of styrene in hot melt adhesives
Implementation Method 2
at least one wax having a congealing point higher than or equal to 60°C
Implementation Method 3
the adhesive has a viscosity less than about 8,500 mPa.s at 120° C
Data Source
AI summary
The present invention relates to hot melt adhesive composition comprising: a) from 22% to 60% by weight of at least one styrene block copolymer (A) (designated as "SBC (A)") comprising:. at least one linear styrene block copolymer (A1); and. optionally at least one styrene diblock copolymer (A2); said styrene block copolymer (A) having: - a styrene content higher than or equal to 38% by weight based on the total weight of SBC (A); and - a diblock content ranging from 0% to 10% by weight based on the total weight of SBC(A); b) from 0.1% to 5% by weight of at least one wax having a congealing point higher than or equal to 60°C and a needle penetration at 25°C lower than or equal to 2 dmm; wherein the hot melt adhesive composition has a viscosity at 120°C higher than or equal to 30 000 mPa.s, and a viscosity at 177°C lower than or equal to 5 000 mPa.s.