Aqueous Polymeric Dispersion Using Organic Carboxylic Acids
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Solution Overview
Problem
Existing polymeric dispersions face challenges in reducing the minimum film-forming temperature (MFFT) and glass transition temperature (Tg) effectively, especially for high Tg polymers, while maintaining mechanical performances and toxicity compliance for various applications, including food coatings and adhesives, where traditional coalescing agents like phthalates are harmful and inefficient at lower contents.
Innovation Solution
An aqueous polymeric dispersion comprising organic carboxylic acids, such as C16 to C25 acids, in their acid form, is used to lower the pH and adjust the MFFT and Tg, with a weight ratio not exceeding 50%, allowing for efficient film formation and recovery of mechanical properties, suitable for both hydrophilic and hydrophobic polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If traditional coalescing agents like phthalates are used to reduce MFFT, then film formation ability is improved, but health and environmental safety deteriorates
Solution Approach 1:
The patent changes the chemical parameters of coalescing agents by using organic carboxylic acids (C1-C4) instead of traditional phthalates. This substitution maintains the MFFT reduction capability while eliminating the harmful effects of phthalates, directly resolving the contradiction between film formation ability and health/environmental safety
Solution Approach 2:
The patent employs volatile organic carboxylic acids (C1-C4) that act as temporary plasticizers during film formation and then evaporate completely. This short-lived approach allows the coalescing function to be performed temporarily without leaving harmful residues, resolving the contradiction by using a disposable, non-toxic alternative to persistent phthalates
2Reliability
If high amounts of protective colloids are used to stabilize dispersion, then water resistance is improved, but MFFT increases
Solution Approach 1:
The patent introduces organic carboxylic acids as intermediary substances that mediate between the protective colloids and polymer particles. These acids act as coalescing agents that facilitate particle fusion at lower temperatures without requiring reduction of the protective colloid content, thus maintaining water resistance while lowering MFFT
Solution Approach 2:
The patent changes the temperature parameter by using organic carboxylic acids that enable film formation at lower temperatures. This allows the system to maintain high protective colloid content for water resistance while achieving acceptable MFFT through the coalescing effect of the added acids
3Temperature
If high boiling point organic solvents are used to reduce MFFT, then film formation ability is improved, but creep resistance deteriorates
Solution Approach 1:
The patent uses volatile organic carboxylic acids (C1-C4) with low boiling points as temporary coalescing agents. These substances perform their function during film formation and then completely evaporate, leaving no residue that would compromise creep resistance. This resolves the contradiction by replacing persistent high-boiling solvents with transient low-boiling acids
4Temperature
If permanent plasticizers are used to reduce MFFT and Tg, then film formation ability is improved, but mechanical properties deteriorate
Solution Approach 1:
The patent employs volatile organic carboxylic acids (C1-C4) that serve as temporary plasticizers during the film formation process. These substances enable particle coalescence and film formation at lower temperatures but then evaporate completely, allowing the polymer to recover its original mechanical properties without permanent plasticization. This resolves the contradiction between film formation ability and mechanical property retention
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 achieves a balance of improved coalescing efficiency, compatibility, and homogeneity, enabling enhanced mechanical and viscoelastic performances while ensuring compliance with environmental regulations, particularly for applications requiring lower toxicity and food contact safety.
Implementation Method 1
the said acid b) being in its acid form, with the pH of the said aqueous dispersion a), being adjusted to be lower than the pKa of the said organic carboxylic acid
Implementation Method 2
specific aqueous polymeric dispersions of polymers with coalescing and/or plasticizing agents for reducing the minimum film-forming temperature (MFFT) of the dispersions
Implementation Method 3
coalescing and/or plasticizing agents for reducing the minimum film-forming temperature (MFFT) of the dispersions and optionally for decreasing the glass transition temperature (Tg) of the polymers
Implementation Method 4
enabling by an MFFT suitable decrease, the film formation (or filmification) ability to a broad range of polymeric aqueous dispersions
Data Source
AI summary
The invention relates to an aqueous polymeric dispersion, characterised in that it comprises : a) at least one polymer in aqueous dispersion having a minimum film- forming temperature (MFFT) between 0 and 100°C, b) from 0.05 to 30%, preferably from 0.1 to 30% by weight with respect to the said aqueous dispersion a), of at least one organic carboxylic acid in C1 to C25, or of their mixtures and, the said organic carboxylic acid b) and its content in the said aqueous dispersion, is selected to be compatible with the said aqueous polymeric dispersion a) as such, and with the said polymer, as polymer itself, the said acid b) is present in its acid form with the pH of the said aqueous dispersion a) being adjusted to be lower than the pKa of the said organic carboxylic acid when the said acid is in C1-C6acids. The invention does also cover a process of preparation, an end-use composition comprising the said aqueous polymeric dispersion for various specific uses in : paints, varnishes, inks, glues, adhesives, construction materials, fibre sizing compositions or textile or leather treatment compositions, or food coatings or packagings. More particularly, the invention concerns peelable coatings : industrial protective coatings and food protective coatings.