Water-Based Polyurethane Dispersion Using DPGDME Solvent
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Solution Overview
Problem
The use of N-methyl-2-pyrrolidone (NMP) in the production of water-based polyurethane dispersions poses reproductive toxicity concerns and regulatory challenges, necessitating a safer, non-flammable solvent with similar solubility properties for coatings applications.
Innovation Solution
A process utilizing dipropylene glycol dimethyl ether (DPGDME) as a solvent in conjunction with 2,2-dimethylolbutanoic acid (DMBA) to form prepolymers, which are then neutralized and dispersed in water, providing improved solubility and film stability without precipitated solids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If NMP is used as solvent in prepolymer synthesis, then good solubility and thermal stability are achieved, but reproductive toxicity and regulatory concerns arise
Solution Approach 1:
The patent changes the chemical parameters of the solvent system by replacing NMP with dipropylene glycol dimethyl ether (DPGDME) and adjusting the acid group-containing polyol composition. This substitution maintains the necessary solubility and reaction performance while eliminating the reproductive toxicity associated with NMP, thus resolving the contradiction between reliability and harmful factors.
2Reliability
If NMP is used as solvent, then high polarity and good solubility properties are obtained, but flammability and environmental concerns increase
Solution Approach 1:
The patent employs dipropylene glycol dimethyl ether (DPGDME) as a replacement solvent that offers comparable solubility properties to NMP but with improved safety profile. DPGDME has lower flammability and better environmental characteristics, allowing the process to maintain reliability while reducing harmful factors through a safer solvent choice.
3Reliability
If conventional solvents are used for DMPA dissolution, then good solubility is achieved, but environmental and health safety profile deteriorates
Solution Approach 1:
The patent creates a composite solvent system using dipropylene glycol dimethyl ether (DPGDME) in combination with acid group-containing polyols (such as DMBA or DMPA). This composite approach achieves the necessary solubility for prepolymer formation while the DPGDME component provides superior environmental and health safety properties compared to conventional solvents like NMP.
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
This approach results in more stable and harder films with desirable properties, replacing NMP while addressing environmental, health, and safety concerns by using a non-toxic solvent, dipropylene glycol dimethyl ether, in the polyurethane dispersion process.
Implementation Method 1
a solvent consisting essentially of dipropylene glycol dimethyl ether
Implementation Method 2
forming a prepolymer with an acid group by contacting (i) a di-isocyanate, (ii) a diol containing an acid group
Implementation Method 3
the contacting step to form the prepolymer with acid group further comprises a metal salt catalyst
Implementation Method 4
neutralizing the acid group of the prepolymer with a base
Implementation Method 5
dispersing the neutralized prepolymer in water
Data Source
AI summary
A prepolymer comprising acid functionality is made by a process comprising the step of contacting: (i) a di-isocyanate, (ii) a diol containing an acid group, and (iii) a polyol without an acid group, the contacting conducted under reaction conditions and in a solvent consisting essentially of dipropylene glycol dimethyl ether. The prepolymer is useful in the preparation of water-based polyurethane dispersions.