Solvent-free Polyurethane Adhesive Oxygen Transfer
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Solution Overview
Problem
Current two-component solvent-free laminating adhesives can impair oxygen and gas transfer through packaging materials, limiting their use in applications requiring high oxygen transfer rates, such as packaging fresh produce.
Innovation Solution
A two-component laminating adhesive composition comprising a Part A prepolymer with a combination of lower and higher molecular weight polyether polyols and a Part B curative, which maintains good adhesive and processing properties while minimizing impact on oxygen transfer rates, using polyether polyols like ARCOL PPG 3025 and ACCLAIM Polyol 8200 with isocyanates like MONDUR MR and Poly G 30-280.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional two-component solvent-free laminating adhesives are used, then good adhesive bonding and processing properties are achieved, but oxygen transfer rate through the packaging material is impaired
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by incorporating specific polyether polyols with controlled molecular weights and hydroxyl values, along with selected isocyanates, to achieve a formulation that maintains bonding performance while allowing oxygen permeation. The specific parameter ranges (e.g., polyol molecular weight 1000-10000, hydroxyl value 10-100) are optimized to balance adhesion and gas transfer properties.
Solution Approach 2:
The adhesive is formulated as a composite system combining multiple polyether polyols of different molecular weights with specific isocyanates. This composite approach creates a material that exhibits both strong adhesive bonding characteristics and enhanced oxygen permeability, resolving the contradiction between bonding performance and gas transfer rate.
2Strength
If adhesive formulations are optimized for strong bonding, then adhesive strength is improved, but oxygen permeability deteriorates
Solution Approach 1:
The patent optimizes the molecular weight distribution of polyether polyols (combining lower MW 1000-3000 for bonding strength and higher MW 3000-10000 for permeability) and controls hydroxyl values (10-100) to achieve a balance where the adhesive provides sufficient bond strength while maintaining oxygen permeability comparable to the uncoated film.
Data Source
AI summary
A solventless two component laminating adhesive comprising a Part A prepolymer and a Part B curative. The prepolymer comprises a lower molecular weight polyether polyol and a higher molecular weight polyether polyol. The laminating adhesive can be applied to flexible films with high oxygen transfer rate to form flexible packaging, particularly for fresh produce, such as pre-prepared salads and other green leaf products.