Aqueous Polymer Dispersion Adhesive Shear Heat Resistance
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Solution Overview
Problem
Existing aqueous polymer dispersions for pressure-sensitive adhesives lack optimal adhesion-cohesion balance, particularly in terms of shear strength, heat resistance, and peel strength, while also facing challenges in water, chemical, and weather resistance.
Innovation Solution
The development of aqueous polymer dispersions comprising essentially non-crosslinked polyurethane particles, obtained by polymerizing polyurethane-forming compounds with specific diol units and radical polymerization of ethylenically unsaturated compounds, which are then used to create adhesives with improved mechanical and chemical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional aqueous polymer dispersions are used for pressure-sensitive adhesives, then adhesion properties can be achieved, but shear strength (cohesion) and heat resistance are insufficient
Solution Approach 1:
The patent uses a composite polymer system combining polyacrylate (providing adhesion and flexibility) with polyurethane (providing cohesion and heat resistance). This composite approach allows the adhesive to simultaneously achieve high shear strength through the polyurethane component's cohesive properties and improved heat resistance through the synergistic interaction between the two polymer phases, resolving the contradiction between adhesion and heat resistance
2Strength
If conventional aqueous polymer dispersions are used, then some adhesion properties are achieved, but peel strength is insufficient
Solution Approach 1:
The patent optimizes the polyurethane component's molecular weight (10,000-500,000 g/mol), glass transition temperature (-50°C to 0°C), and composition ratios to achieve optimal peel strength. By carefully controlling these parameters, the adhesive maintains the right balance between adhesion (peel strength) and cohesion (shear strength), allowing high peel strength without sacrificing overall adhesive performance
3Reliability
If existing adhesive formulations are used, then basic adhesive properties are achieved, but water, chemical and weather resistance are insufficient
Solution Approach 1:
The patent extracts and eliminates problematic components from conventional adhesive formulations, specifically avoiding organic solvents and using an aqueous-based system. The polyurethane-polyacrylate composite formulation inherently provides water and chemical resistance without requiring additional protective additives or complex multi-component systems, thereby achieving improved reliability while maintaining ease of manufacture
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 resulting adhesives exhibit enhanced shear strength, heat resistance, and peel strength, along with excellent water, chemical, and weather resistance, and facilitate a cost-effective production process.
Implementation Method 1
the polyurethane PU being obtainable by polymerization of polyurethane-forming compounds PU-M
Implementation Method 2
radical polymerization of ethylenically unsaturated compounds
Data Source
AI summary
The invention relates to aqueous polymer dispersions for adhesive compounds, to a method for producing same, and to the use of the aqueous polymer dispersions in order to produce adhesives. The aqueous polymer dispersions can be obtained by a method having the steps of A) providing an aqueous dispersion of at least one substantially non-crosslinked polyurethane PU in the form of dispersed polyurethane particles, said polyurethane PU being obtainable by polymerizing polyurethane-forming compounds PU-M containing at least one diol PU-M2 which has at least one poly-C2-C14-alkylene ether group that has at least one repeating unit of the formula (i) -O-CHRa-CH2-Rb- (i), where Ra represents hydrogen or C1-C12-alkyl, and Rb represents a bond or C1-C3-alkenyl, wherein Ra does not represent hydrogen if Rb is a bond, and the PU has substantially no ethylenically unsaturated double bonds and has a gel content of <20%; and B) radically polymerizing a monomer composition PA-M from radically polymerizable ethylenically unsaturated compounds, comprising at least one monomeric ethylenically unsaturated compound which has a water solubility of < 60 g/l at 20°C and 1 bar as the main component, said monomer composition having a theoretical glass transition temperature according to Fox of maximally 50 °C, in the aqueous dispersion of the at least one polyurethane PU. The main quantity of the monomer composition PA-M is added to the aqueous polymer dispersions of the at least one polyurethane PU in the course of the polymerization process.