Solvent-Free Polyurethane Adhesive Viscosity Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing solvent-free polyurethane adhesive compositions for laminating PET and aluminum foil in food packaging face challenges in achieving desirably low viscosity and satisfactory optical appearance.
Innovation Solution
A solvent-free polyurethane adhesive composition comprising an isocyanate group-containing component with an isocyanate-terminated polyurethane prepolymer, obtained by reacting a polyol mixture of polyester and polyether polyols with a stoichiometric excess of polyisocyanate, and a hydroxyl group-containing component, with an NCO content of between 10% to 14% by weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If solvent-free polyurethane adhesive compositions are used for laminating PET and aluminum foil, then environmental safety and food packaging suitability are improved, but viscosity control and optical appearance become problematic
Solution Approach 1:
The patent changes the chemical parameters of the adhesive composition by specifying precise NCO content ranges (10-14% by weight) and defining specific polyol mixtures with controlled molecular weights. This parameter optimization enables the solvent-free adhesive to achieve both low viscosity and satisfactory optical appearance while maintaining environmental safety.
2Object-affected harmful factors
If solvent-free polyurethane adhesive compositions are used for laminating PET and aluminum foil, then environmental safety and food packaging suitability are improved, but optical appearance becomes problematic
Solution Approach 1:
The patent optimizes chemical parameters including NCO content (10-14% by weight) and polyol molecular weight ranges to control the adhesive's reactivity and curing characteristics. This precise parameter control prevents excessive foam formation and ensures satisfactory optical appearance on high-barrier films like PET and aluminum foil.
Solution Approach 2:
The patent uses a composite polyol system combining polyester polyols and polyether polyols in specific ratios. This composite approach balances the adhesive's viscosity, flexibility, and curing properties, enabling both environmental safety and optical appearance requirements to be met simultaneously.
3Strength
If free isocyanate-containing adhesives are used, then adhesive strength is improved, but carbon dioxide bubble formation causing appearance problems occurs
Solution Approach 1:
The patent carefully controls the NCO content within a specific range (10-14% by weight) rather than using high free isocyanate formulations. This moderate parameter setting provides sufficient adhesive strength while limiting the amount of isocyanate available to react with moisture and form CO2 bubbles, thus preventing appearance defects.
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 low viscosity and satisfactory optical appearance when laminated on PET and aluminum foil, addressing the limitations of prior art while ensuring food safety and packaging integrity.
Implementation Method 1
reacting a polyol mixture comprising: (a) at least one polyester polyol obtained by reacting a reactant mixture comprising: (i) at least one polycarboxylic acids, (ii) neopentyl glycol, and (iii) at least one polyol with a stoichiometric excess of at least one polyisocyanate
Implementation Method 2
adhesive composition comprising: (A) at least one isocyanate group-containing component comprising at least one isocyanate-terminated polyurethane prepolymer... and (B) at least one hydroxyl group-containing component
Data Source
AI summary
The present invention relates to a solvent-free polyurethane adhesive composition and the use thereof. In particular, the present invention provides a solvent-free polyurethane adhesive composition comprising: (A) at least one isocyanate group-containing component comprising at least one isocyanate-terminated polyurethane prepolymer obtained by reacting a polyol mixture comprising: (a) at least one polyester polyol obtained by reacting a reactant mixture comprising: (i) at least one polycarboxylic acids selected from at least one aliphatic dicarboxylic acid and at least one aromatic dicarboxylic acid, (ii) neopentyl glycol, and (iii) at least one polyol having a weight average molecular weight of from 50 to 300 g/mol other than neopentyl glycol, and (b) at least one polyether polyol having a weight average molecular weight of from 200 to 4000 g/mol, with a stoichiometric excess of at least one polyisocyanate, and (B) at least one hydroxyl group-containing component; wherein the isocyanate-containing component (A) has an NCO content of from more than 10% to less than 14% by weight.