Three-Component Polyurethane Primer for Blister-Free Concrete Adhesion
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Solution Overview
Problem
Existing flooring primer and scratch coat compositions, particularly on concrete surfaces, face issues with blister formation on freshly cured substrates and limited open time, restricting application flexibility and adhesion performance across varying temperatures.
Innovation Solution
A three-component composition comprising a polyol component, a methylene diphenyl diisocyanate (MDI) product with partial pre-polymerization, and a powder component, including hydraulic binders, with specific ratios of 2-(Dimethylamino)ethanol and tertiary amines to enhance workability and prevent blistering across a broad temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If one-component polyurethane systems are used on freshly cured concrete substrates, then adhesion is improved, but blister formation occurs
Solution Approach 1:
The polyol component is divided into two distinct polyols with different molecular weights: a high molecular weight polyol (800-30,000 g/mol) providing adhesion and a low molecular weight polyol (48-800 g/mol) preventing blister formation. This segmentation allows each polyol to perform its specific function without interfering with the other.
Solution Approach 2:
The invention creates a composite polyol system combining high and low molecular weight polyols in specific ratios. This composite material integrates the adhesive properties of high molecular weight polyols with the blister-preventing characteristics of low molecular weight polyols, achieving both adhesion strength and surface integrity.
2Strength
If epoxy-based or acrylate-based compositions are used, then adhesion is improved, but they cannot be used on freshly cured concrete substrates
Solution Approach 1:
The invention changes the chemical composition parameters by using a polyol-polyisocyanate-hydraulic binder system instead of epoxy or acrylate systems. This parameter change enables the composition to be applied on freshly cured concrete substrates while maintaining strong adhesion, as the polyol component provides flexibility and the hydraulic binder ensures bonding to green concrete.
3Strength
If conventional primer layers are applied, then adhesion is achieved, but the open time is limited requiring multiple jobsite visits
Solution Approach 1:
The invention introduces dynamic control of the curing process through a polyisocyanate component that reacts with the polyol component over an extended period. The use of specific polyisocyanates with controlled reactivity and the inclusion of hydraulic binders create a dynamic system that maintains workability and open time while progressively achieving adhesion, allowing the applicator to complete all works in one day.
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 provides a longer open time and improved workability from 5-35°C, preventing blister formation and ensuring quick surface accessibility and adhesion, suitable for industrial flooring applications.
Implementation Method 1
a polyol component (A) comprising at least one polyol P1a... and at least one polyol P1b... a polyisocyanate component (B) comprising a methylene diphenyl diisocyanate (MDI) product
Implementation Method 2
a powder component (C) comprising at least one hydraulic binder, preferably cement and/or calcined paper sludge
Implementation Method 3
The composition contains 2-(Dimethylamino)ethanol, whereby the molar ratio of the 2-(Dimethylamino)ethanol to the OH-groups of the polyol P1a is between 0.0008 and 0.013
Data Source
AI summary
A three component composition consisting of a polyol component (A) including at least two polyols, one with high, one with low molecular weight and water, a polyisocyanate component (B) including a methylene diphenyl diisocyanate (MDI) product with an average NCO functionality of at least 2.5, or a methylene diphenyl diisocyanate (MDI) product with an average NCO functionality of at least 2 and at least one further polyol with an amount of between 1% and 30% based on the weight of the polyisocyanate component (B), wherein the MDI product and the polyol have reacted at least partially, and a powder component (C) including at least one hydraulic binder, preferably cement and/or calcined paper sludge, preferably a calcium compound selected from calcium hydroxide and/or calcium oxide, and optionally one or more aggregates.