Synthetic Leather Urethane Composition to Reduce Odor and Bleeding
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Solution Overview
Problem
Current synthetic leather products face challenges with strong odors, inadequate peel strength, and bleeding issues, particularly in the adhesive layer, which limits the use of water-based urethane resins due to these deficiencies.
Innovation Solution
A synthetic leather composition comprising a base, an adhesive layer formed with a urethane resin using aromatic polyisocyanate, and a skin layer with an anionic urethane resin and anionic surfactant, optimizing intermolecular interactions for enhanced peel strength, hydrolysis resistance, and reduced odor and bleeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water-based urethane resin is used in the adhesive layer, then environmental compliance is improved, but peel strength deteriorates
Solution Approach 1:
The patent changes the chemical parameters of the urethane resin by incorporating aromatic polyisocyanate components and controlling the NCO/OH ratio to 1.05-1.30, which enhances intermolecular interactions and maintains high peel strength in water-based formulations
Solution Approach 2:
The adhesive layer uses a composite urethane resin system combining aromatic polyisocyanate (TDI or MDI) with specific polyols and chain extenders, creating a multi-component system that achieves both environmental compliance and mechanical performance
2Object-affected harmful factors
If water-based urethane resin is used in the skin layer, then environmental compliance is improved, but odor increases due to neutralizer
Solution Approach 1:
The patent reduces the anionic group concentration to 0.25 mmol/g or less, which minimizes the amount of neutralizer required and consequently reduces odor generation while maintaining the water-based formulation benefits
Solution Approach 2:
The patent employs anionic surfactants as temporary processing aids that facilitate water-based formulation during manufacturing but are present in minimal amounts in the final product, reducing their impact on odor
3Object-affected harmful factors
If water-based urethane resin is used in the adhesive layer, then environmental compliance is improved, but bleeding increases
Solution Approach 1:
The patent optimizes the molecular weight and chemical composition of the urethane resin, controlling the NCO/OH ratio and incorporating aromatic polyisocyanate to enhance intermolecular forces that prevent resin migration and bleeding
Solution Approach 2:
The patent utilizes hydrogen bonding and intermolecular interactions (analogous to fluid pressure relationships) to create a cohesive adhesive layer structure that resists bleeding under heat and pressure conditions
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 synthetic leather with improved peel strength, hydrolysis resistance, and reduced odor and bleeding, enabling its use in durable applications like automotive interiors and sports shoes, where water-based urethane resins were previously unsuitable.
Implementation Method 1
a urethane resin (A) produced using an aromatic polyisocyanate (a1) as a raw material
Implementation Method 2
an anionic surfactant (Z)
Implementation Method 3
an anionic urethane resin (X) having an anionic group concentration of 0.25 mmol/g or less
Data Source
AI summary
The present invention provides a synthetic leather including at least a base (i), an adhesive layer (ii), and a skin layer (iii). The adhesive layer (ii) is formed of a urethane resin composition including a urethane resin (A) produced using an aromatic polyisocyanate (a1) as a raw material and water (B). The skin layer (iii) is formed of a urethane resin composition including an anionic urethane resin (X) having an anionic group concentration of 0.25 mmol/g or less, water (Y), and an anionic surfactant (Z). The aromatic polyisocyanate (a1) preferably includes toluene diisocyanate. The urethane resin (A) has an aromatic ring concentration of 0.1 to 2.5 mol/kg.