Self-Emulsifying Polyester Resin for Water Dispersions
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Solution Overview
Problem
Existing polyester resin water dispersions often require emulsifiers and organic solvents, leading to issues like reduced adhesive properties, inferior water resistance, and challenges with heat resistance, particularly when used in applications requiring high hydrolysis resistance and heat stability.
Innovation Solution
A polyester resin with a specific chemical structure, characterized by a high acid value and molecular weight range, which forms a stable aqueous emulsion without emulsifiers or organic solvents, utilizing a polyvalent carboxylic acid and polyhydric alcohol polymerization, and incorporating curing agents for enhanced adhesive and water-resistant properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an emulsifier is used to prepare water dispersion of polyester resin, then the resin can be dispersed in water, but the adhesive property lowers due to emulsifier remaining at the interface
Solution Approach 1:
The polyester resin is designed to form a water dispersion without requiring external emulsifiers. The resin itself possesses the necessary properties to disperse in water through its molecular structure containing hydrophilic groups, enabling it to serve its own emulsification function and maintain adhesive properties.
Solution Approach 2:
The emulsifier component is completely removed from the system. Instead of using separate emulsifying agents, the invention extracts the emulsification function from the formulation and integrates it directly into the polyester resin molecule through incorporation of hydrophilic groups.
2Ease of operation
If hydrophilic material is added to improve water dispersibility, then water resistance of the coat deteriorates
Solution Approach 1:
The polyester resin incorporates hydrophilic groups at specific locations within the polymer chain rather than uniformly throughout. This localized placement of hydrophilic character (such as carboxyl groups or hydroxyl groups) provides water dispersibility while the bulk of the polymer maintains hydrophobic character for water resistance.
Solution Approach 2:
The invention creates a composite molecular structure within the polyester resin, combining hydrophobic polyester backbone segments with hydrophilic functional groups. This molecular-level composite structure enables simultaneous achievement of water dispersibility and water resistance.
3Ease of operation
If polylactic acid is used as the polyester backbone, then self-emulsifying ability is achieved, but heat resistance and hydrolysis resistance are reduced
Solution Approach 1:
The invention changes the chemical parameters of the polyester backbone from polylactic acid to other polyester structures (such as polyadipic acid, polysebacic acid, or copolyesters). By adjusting the molecular composition and functional groups while maintaining appropriate acid values and molecular weights, the resin achieves self-emulsifying ability without sacrificing heat and hydrolysis resistance.
Solution Approach 2:
The invention creates a composite molecular structure within the polyester resin, combining hydrophobic polyester backbone segments with hydrophilic functional groups. This molecular-level composite structure enables simultaneous achievement of water dispersibility and water resistance.
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 solution enables the formation of a stable aqueous emulsion with excellent adhesive properties and improved water resistance, while maintaining heat resistance superior to polylactic acid, allowing for broader application in coatings, inks, and packaging materials.
Implementation Method 1
a polyester resin having a self-emulsifying function which is able to form a stable aqueous emulsion without using any emulsifier and organic solvent
Implementation Method 2
containing a basic compound and water... wherein the polyester resin, a basic compound and water are mixed without addition of any emulsifier and organic solvent
Data Source
AI summary
The present invention provides a polyester resin having a self-emulsifying function which is able to form an aqueous emulsion without using any emulsifier and organic solvent. The present invention also provides a water dispersion, an aqueous adhesive, an aqueous ink, a laminate and a packaging material containing the above polyester resin, as well as a method for preparing the water dispersion. A polyester resin represented by the following chemical structure of formula (I) and having an acid value of 250 to 2,500 eq/106 g and a number-average molecular weight of 2,000 to 50,000: (X-O)r-W-(O-(CO-Z-CO-O-Y-O)p-X)q ...... (I) wherein W is a (q + r)-valent organic group; (CO-Z-CO-O-Y-O) is a skeleton of polyester resin prepared by polymerization using a polyvalent carboxylic acid ingredient Z and a polyhydric alcohol ingredient Y as polymerizing ingredients; X is a residue of polybasic acid having two or more carboxyl groups or is hydrogen (except the case wherein all of X in numbers of (q + r) are hydrogen); X, Y and Z each may be the same as or different from each other and, even in the same repetitive unit, X, Y and Z each may be the same as or different from each other; average value of p is 3 or more, average value of q is more than 0 and is 15 or less, average value of r is 0 or more and is less than 15, and (q + r) is 3 or more and 15 or less.