Plasticizer-Free Acrylic Sealants via Phase Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional acrylic and emulsion polymers used in caulks and sealants face challenges in providing both flexibility and durability across a wide temperature range, often requiring plasticizers that are expensive, unsafe, and contribute to tackiness and dirt pickup.
Innovation Solution
Development of aqueous caulk and sealant compositions comprising acrylic emulsion copolymers with a broad measured glass transition temperature, featuring separate soft and hard phases, achieved through powerfeed emulsion polymerization, which are substantially free of plasticizers, allowing for improved flexibility, low tack, and tensile properties across a wide temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional acrylic and emulsion polymers are made soft for ease of application and low temperature flexibility, then flexibility and ease of operation improve, but block resistance and durability worsen, especially at above room temperature
Solution Approach 1:
The polymer is segmented into distinct soft and hard phases through copolymerization. The soft phase (from monomers with Tg ≤ -20°C) provides flexibility and ease of application, while the hard phase (from monomers with Tg of 20°C to 140°C) provides block resistance and durability. This phase separation allows each phase to perform its specialized function without compromising the other.
Solution Approach 2:
Different regions of the polymer matrix have different properties. The soft phase domains provide local flexibility for application and low-temperature performance, while the hard phase domains provide local rigidity for block resistance. This local differentiation of properties resolves the contradiction between softness and hardness.
2Reliability
If conventional acrylic and emulsion polymers are made hard for durability and low tack, then reliability and strength improve, but ease of operation worsens due to difficulty in application
Solution Approach 1:
The polymer is segmented into distinct soft and hard phases through copolymerization. The soft phase (from monomers with Tg ≤ -20°C) provides flexibility and ease of application, while the hard phase (from monomers with Tg of 20°C to 140°C) provides block resistance and durability. This phase separation allows each phase to perform its specialized function without compromising the other.
Solution Approach 2:
Different regions of the polymer matrix have different properties. The soft phase domains provide local flexibility for application and low-temperature performance, while the hard phase domains provide local rigidity for block resistance. This local differentiation of properties resolves the contradiction between softness and hardness.
3Ease of operation
If plasticizers are added to achieve softness and flexibility, then ease of operation and low temperature flexibility improve, but cost and safety worsen, and tackiness and dirt pickup increase
Solution Approach 1:
The invention extracts and eliminates plasticizers from the formulation entirely. Instead of using external plasticizer additives, the desired softness and flexibility are achieved through the intrinsic soft phase of the copolymer, which is formed from monomers with low glass transition temperatures (≤ -20°C). This eliminates the harmful effects of plasticizers including tackiness, dirt pickup, and safety concerns.
Solution Approach 2:
The invention changes the fundamental approach to achieving softness by modifying the polymer's chemical composition rather than adding additives. By incorporating monomers with very low Tg values into the copolymer structure, the polymer itself becomes inherently soft and flexible without requiring plasticizers. This parameter change in the polymer's molecular structure replaces the need for external plasticizing agents.
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 compositions deliver consistent performance at both cold and warm temperatures without the use of plasticizers, maintaining easy cleaning attributes and providing improved performance properties throughout a range of temperatures.
Implementation Method 1
aqueous emulsion copolymer having a broad measured glass transition temperature (broad measured Tg) by differential scanning calorimetry (DSC), a soft phase and hard phase domains
Implementation Method 2
which are the copolymerization product of a monomer composition which when polymerized would provide a polymer having a calculated Tg of below −20° C. and second monomer composition which when polymerized would provide a polymer having a calculated Tg of from 20° C. to 140° C.
Data Source
AI summary
The present invention provides aqueous caulk or sealant compositions that are substantially free of any plasticizer comprising an aqueous emulsion copolymer having a broad measured glass transition temperature by differential scanning calorimetry (DSC), soft phases and hard phases, and two separate Tan Delta transition temperatures as measured by dimensional mechanical analysis (DMA), (ii) one or more filler in a filler to binder ratio of up to 4:1, and (iii) from 0.2 to 5 wt. % as solids, based on the total weight of the composition, of one or more thickener or rheology modifier. In addition, the invention provides methods of making the composition comprising polymerizing by gradually adding from a flask into a polymerization vessel a soft monomer composition, and, after feeding at least 20 wt. % of such composition in the vessel, gradually adding into the flask a hard comonomer composition, feeding all flask contents into the vessel and polymerizing.