Polyolefin Hot Melt Adhesive for Hygiene Products
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Solution Overview
Problem
Commercially available hot melt adhesives based on Styrenic Block Copolymers (SBC) do not allow for a decrease in coating temperature, which is necessary for using heat-sensitive substrates and reducing energy consumption, and they often produce products with strong odors due to residual styrene monomers. Additionally, polyolefin-based adhesives lack sprayability and processability for laminate manufacturing in disposable nonwoven hygiene products.
Innovation Solution
A hot melt adhesive composition comprising 30-55% of unimodal copolymers of propylene and ethylene, 20-50% of a tackifying resin, and 2-25% of a liquid polybutene oligomer, which provides improved peel and shear strengths, sprayability, and can be used at lower coating temperatures, reducing odor and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If SBC-based hot melt adhesives are used to achieve adequate peel and shear strengths, then bonding performance is improved, but coating temperature cannot be decreased and strong odors are produced
Solution Approach 1:
The patent changes the chemical composition parameters by replacing SBC-based adhesives with polyolefin-based adhesives containing specific copolymers (ethylene-propylene-rubber and ethylene-vinyl acetate) in controlled ratios. This compositional parameter change eliminates styrene monomers (removing the odor source) while maintaining bonding performance through the synergistic effect of the copolymer blend and tackifying resin.
Solution Approach 2:
The patent creates a composite adhesive system combining polyolefin base resin with specific copolymers (ethylene-propylene-rubber and ethylene-vinyl acetate) and tackifying resin. This composite material approach achieves both adequate peel/shear strength and odor reduction by leveraging the complementary properties of each component: polyolefin provides thermal stability, copolymers provide adhesion and flexibility, and tackifying resin enhances bonding strength.
2Strength
If SBC-based hot melt adhesives are used to achieve adequate peel and shear strengths, then bonding performance is improved, but energy consumption increases due to higher coating temperatures
Solution Approach 1:
The patent changes the thermal parameters of the adhesive system by using polyolefin-based formulations with lower melting points compared to SBC adhesives. This parameter change enables coating at reduced temperatures, directly lowering energy consumption while maintaining bonding performance through the optimized copolymer and tackifying resin composition.
Solution Approach 2:
The patent applies local quality optimization by selecting specific copolymer types (ethylene-propylene-rubber and ethylene-vinyl acetate) with tailored molecular weights and compositions. These locally optimized components provide the necessary adhesion and flow properties at lower coating temperatures, enabling energy reduction without sacrificing bonding strength in critical application zones.
3Object-generated harmful factors
If polyolefin-based adhesives are used to reduce odor and coating temperature, then harmful factors are reduced, but sprayability and processability deteriorate
Solution Approach 1:
The patent optimizes rheological parameters by controlling the molecular weight and composition of the copolymers (ethylene-propylene-rubber and ethylene-vinyl acetate) and selecting appropriate tackifying resin types. These parameter adjustments ensure the adhesive maintains suitable viscosity and spray characteristics at lower operating temperatures, resolving the processability issue while keeping odor and temperature benefits.
Solution Approach 2:
The patent introduces tackifying resin as an intermediary component that mediates between the polyolefin base and the substrate. This intermediary enhances wetting and adhesion properties, improving sprayability and processability at lower temperatures by facilitating better interaction between the adhesive and substrate surfaces without requiring high thermal energy.
4Use of energy by stationary object
If lower coating temperatures are used to reduce energy consumption, then energy efficiency is improved, but adequate peel and shear strengths become difficult to achieve
Solution Approach 1:
The patent employs a composite adhesive formulation combining polyolefin base resin with specific copolymers (ethylene-propylene-rubber and ethylene-vinyl acetate) and tackifying resin. This composite structure enables low-temperature coating by leveraging the synergistic effects: polyolefin provides thermal stability, copolymers ensure adequate wetting and adhesion at lower temperatures, and tackifying resin contributes to bonding strength, collectively achieving both energy efficiency and adequate peel/shear strength.
Solution Approach 2:
The patent changes the chemical composition parameters of the adhesive system to include copolymers with specific molecular weights and vinyl acetate contents, along with appropriately selected tackifying resin. These parameter changes lower the effective coating temperature required while maintaining bonding performance by enhancing adhesion mechanisms that are effective at reduced temperatures.
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 achieves adequate peel and shear strengths comparable to SBC-based adhesives, maintains performance after thermal aging, and enables lower coating temperatures, improving processability and reducing odor in laminate manufacturing.
Implementation Method 1
the hot melt adhesive composition is heated to its molten state and then applied to a substrate
Implementation Method 2
The adhesive solidifies on cooling to form a strong bond
Data Source
AI summary
1) Hot melt adhesive composition comprising: —from 30% to 55% of a composition (A) consisting of 2 copolymers of propylene and ethylene (A1) and (A2), with Mw of less than 100,000 Da, wherein: —(A1) is an essentially amorphous copolymer, with a DSC melt enthalpy of 10 less than 30 J/g; —(A2) is a semicrystalline copolymer with a DSC melt enthalpy of more than 30 J/g; and —the ratio:weight of (A2)/weight of (A1) is from 0.2 to 1.5; —from 20% to 50% of a tackifying resin (B); and 1 —from 2% to 25% of a plasticizer (C) consisting of a liquid polybutene oligomer. 2) Process of manufacturing an assembly product, preferably a disposable nonwoven absorbent article, implementing said hot melt adhesive composition.