Multi-Stage Vinyl Ester Copolymer Dispersion for Low VOC Coatings
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Solution Overview
Problem
Existing aqueous polymer dispersions based on vinyl ester copolymers fail to provide sufficient blocking resistance and high gloss properties while minimizing VOC levels and maintaining low binder content, especially in low pigment volume concentration formulations.
Innovation Solution
A multi-stage polymer dispersion is manufactured through step polymerization of monomer mixtures containing vinyl acetate and specific vinyl esters of aromatic and aliphatic carboxylic acids, with distinct glass transition temperatures, using free radical emulsion polymerization in the presence of surfactants and adhesion improving monomers, resulting in a vinyl ester copolymer with improved blocking resistance and gloss properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If aqueous polymer dispersions based on vinyl ester copolymers are used to reduce binder content, then VOC levels are minimized, but blocking resistance and gloss properties become insufficient
Solution Approach 1:
The patent uses composite materials by combining vinyl acetate copolymer (50-90 wt%) with vinyl ester of aromatic carboxylic acid (10-50 wt%) to create a multi-component binder system. This composite approach allows the dispersion to achieve both low VOC levels and improved blocking resistance, as the aromatic vinyl ester component specifically enhances blocking resistance while the vinyl acetate provides film formation and gloss properties.
Solution Approach 2:
The patent applies parameter changes by carefully controlling the glass transition temperatures (Tg) of the polymer components. The vinyl acetate copolymer has Tg of -50 to -100°C and the vinyl ester of aromatic carboxylic acid has Tg of -50 to -100°C, with the final dispersion achieving blocking resistance through specific Tg combinations. This parameter control enables the system to maintain low binder content while achieving sufficient blocking resistance.
2Object-generated harmful factors
If binder content is reduced to minimize VOC, then environmental harm is reduced, but gloss properties of dried coatings deteriorate
Solution Approach 1:
The patent creates a composite binder system where vinyl acetate copolymer (providing gloss and film formation) is combined with vinyl ester of aromatic carboxylic acid (providing blocking resistance). This composite approach maintains high gloss properties even at reduced binder content (low PVC), as each component contributes its specific properties to the overall coating performance.
Solution Approach 2:
The patent applies local quality by assigning specific functional roles to different polymer components: vinyl acetate copolymer primarily provides gloss and film formation, while vinyl ester of aromatic carboxylic acid primarily provides blocking resistance. This functional differentiation allows the coating to achieve multiple performance targets simultaneously with minimal binder content.
3Reliability
If multi-stage polymer dispersion is used to improve blocking resistance, then coating reliability improves, but manufacturing process complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the polymerization process into two distinct stages: first stage polymerization of vinyl acetate and vinyl ester of aromatic carboxylic acid, followed by second stage polymerization with vinyl ester of aliphatic carboxylic acid. This segmented approach enables precise control over polymer composition and Tg distribution, achieving superior blocking resistance while maintaining manageable manufacturing complexity through systematic process design.
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 multi-stage polymer dispersion achieves excellent blocking resistance and high gloss with minimal VOC levels, meeting the requirements for low binder content coatings and demonstrating at least two distinct glass transition temperatures.
Implementation Method 1
polymerizing a monomer mixture (A) comprising a-i) vinyl acetate and a-ii) at least one vinyl ester of an aromatic carboxylic acid via free radical emulsion polymerization to obtain a copolymer (A)
Data Source
AI summary
The present invention describes a method for the manufacturing of a multi-stage polymer by the following steps:a) polymerizing monomer mixture (A) comprisinga-i) vinyl acetate anda-ii) at least one vinyl ester of an aromatic carboxylic acidvia free radical emulsion polymerization to obtain copolymer (A); andb) polymerizing monomer mixture (B) comprisingb-i) vinyl acetate andb-ii) at least one vinyl ester of aliphatic branched or unbranched carboxylic acids having at least 3 carbon atoms,via free radical emulsion polymerization in the presence of copolymer (A) to obtain the multi-stage polymerwith the proviso that said monomer mixture (B) can also be polymerized first to obtain a copolymer (B) and subsequently monomer mixture (A) is polymerized in the presence copolymer (B) to obtain the multi-stage polymer.