Polyether-Urethane-Urea Additives for Latex Paint Open Time
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Solution Overview
Problem
Latex paints often face challenges in maintaining open time without compromising block resistance, as existing additives can degrade these properties.
Innovation Solution
A composition comprising a hydrophilic polyurethane polymer with polymerized units of a water-soluble polyol and aliphatic polyisocyanate, where ethylene oxide units make up at least 85 wt%, combined with a saccharide and ethoxylated glycerol, is used to enhance open time without significantly affecting block resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If existing open time additives (e.g., phenolic glycidyl ether adducts) are used to improve open time, then open time is extended, but block resistance and tack resistance are substantially degraded
Solution Approach 1:
The invention changes the chemical parameters of the open time additive by using a polyether-urethane-urea polymer with specific molecular weight (5,000-1,000,000), specific polyol composition (polyethylene glycol and ethoxylated glycerol in 90:10 to 50:50 weight ratio), and at least 80 wt% ethylene oxide units. These parameter changes enable the additive to extend open time without substantially degrading block resistance and tack resistance, unlike conventional phenolic-based additives.
Solution Approach 2:
The invention employs a composite polyether-urethane-urea polymer structure combining multiple functional groups (urethane, urea, and polyether segments) with specific composition ratios. This composite structure provides both open time extension capability and maintains film formation properties, resolving the contradiction between extended open time and maintained block resistance.
2Duration of action of moving object
If existing open time additives are used to improve open time, then open time is extended, but tack resistance is substantially degraded
Solution Approach 1:
The invention changes the chemical parameters of the open time additive by using a polyether-urethane-urea polymer with specific molecular weight (5,000-1,000,000), specific polyol composition (polyethylene glycol and ethoxylated glycerol in 90:10 to 50:50 weight ratio), and at least 80 wt% ethylene oxide units. These parameter changes enable the additive to extend open time without substantially degrading tack resistance, unlike conventional phenolic-based additives.
Solution Approach 2:
The invention employs a composite polyether-urethane-urea polymer structure combining multiple functional groups (urethane, urea, and polyether segments) with specific composition ratios. This composite structure provides both open time extension capability and maintains film formation properties, resolving the contradiction between extended open time and maintained tack resistance.
3Stability of the object's composition
If HEUR thickeners are used to achieve desirable rheological characteristics, then viscosity and rheological properties are improved, but open time is not adequately extended
Solution Approach 1:
The polyether-urethane-urea polymer serves multiple functions simultaneously: it acts as a thickener providing desirable rheological characteristics (like HEURs) and as an open time extender (unlike HEURs). The specific composition with polyethylene glycol and ethoxylated glycerol, and at least 80 wt% ethylene oxide units, enables this multi-functionality, resolving the contradiction between rheological performance and open time extension.
Data Source
AI summary
A composition comprising: (a) a hydrophilic polyurethane comprising polymerized units of: (i) a water-soluble polyol having hydroxyl functionality from two to four and a weight-average molecular weight from 800 to 16,000; and (ii) an aliphatic polyisocyanate having isocyanate functionality from two to six; wherein polymerized ethylene oxide units comprise at least 85 wt% of said hydrophilic polyurethane; and at least one of: (b) a saccharide having at least 5 hydroxyl groups and Mw from 300 to 4,000; (c) a dispersant polymer having Mw from 700 to 50,000 and from 10 to 55 wt% polymerized residues of C3-C6 carboxylic acid monomer and (d) a surfactant having HLB > 11 and 12 to 100 polymerized units of ethylene oxide.