Synthetic leather
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Solution Overview
Problem
Current synthetic leather products face challenges in achieving high peel strength and chemical resistance, particularly in applications requiring durability such as automotive interiors and sports shoes, due to the limitations of solvent-based urethane resins and the insufficient performance of water-based urethane resins in adhesive and skin layers.
Innovation Solution
The development of synthetic leather comprising a base, adhesive layer, and skin layer, both formed using a urethane resin composition produced with an aromatic polyisocyanate as a raw material, which enhances peel strength, chemical resistance, and hydrolysis resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water-based urethane resin is used in adhesive layer, then environmental compliance is improved, but peel strength deteriorates
Solution Approach 1:
The invention changes the chemical parameters of the urethane resin by specifying functional group concentrations (carboxyl groups 0.05-0.50 mmol/g, hydroxyl groups 1.5-5.0 mmol/g) to achieve both water-based formulation and high peel strength. This parameter optimization resolves the contradiction between environmental compliance and adhesive performance
Solution Approach 2:
The invention creates a composite urethane resin system combining multiple functional groups (carboxyl, hydroxyl, isocyanate) in specific proportions to achieve synergistic effects. The composite nature of the resin provides both water-based compatibility and high bonding strength, resolving the contradiction between environmental compliance and peel strength
2Reliability
If water-based urethane resin is used in skin layer, then chemical resistance is improved, but mechanical strength deteriorates
Solution Approach 1:
The invention optimizes the concentration parameters of functional groups in the urethane resin (carboxyl 0.05-0.50 mmol/g, hydroxyl 1.5-5.0 mmol/g) to achieve a balance between chemical resistance and mechanical strength. The specific parameter range ensures both water-based formulation benefits and adequate mechanical performance
Solution Approach 2:
The invention applies different functional group concentrations to different layers (adhesive layer vs. skin layer) to optimize local properties. The adhesive layer benefits from higher carboxyl content for bonding, while the skin layer maintains appropriate functional group balance for both chemical resistance and mechanical strength
3Strength
If aromatic polyisocyanate is used as raw material, then peel strength is improved, but hydrolysis resistance deteriorates
Solution Approach 1:
The invention carefully controls the concentration of isocyanate groups (0.1-2.0 mmol/g) in combination with carboxyl and hydroxyl groups to achieve optimal balance between peel strength and hydrolysis resistance. The parameter optimization prevents excessive isocyanate content that would cause hydrolysis while maintaining adequate bonding strength
Solution Approach 2:
The invention creates a composite urethane resin system where aromatic polyisocyanate is combined with polyol and controlled amounts of carboxyl-containing compounds. This composite structure provides the benefits of aromatic polyisocyanate for peel strength while the balanced functional group composition mitigates hydrolysis susceptibility
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) and the skin layer (iii) are both formed of a urethane resin composition including a urethane resin and water, the urethane resin being produced using an aromatic polyisocyanate as a raw material. The urethane resin composition forming the adhesive layer (ii) preferably includes a urethane resin (A) and water (B), the urethane resin (A) being produced using an aromatic polyisocyanate (a1) as a raw material. The aromatic polyisocyanate (a1) preferably includes toluene diisocyanate. It is preferable that the urethane resin (A) include an anionic group and the concentration of the anionic group in the urethane resin (A) be 0.35 mmol/g or less.