IPN Silicone Emulsion for Leather Coating Defects
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Solution Overview
Problem
Existing aqueous silicone gum emulsions have poor compatibility with polyurethane coating compositions due to large particle sizes, leading to defects like pinholes in leather coatings, and current solutions such as silicone-acrylic copolymers are complex and expensive to produce.
Innovation Solution
Development of aqueous emulsions with an interpenetrating polymer network (IPN) of silicone gum and crosslinked organic polymer, which are mechanically mixed to achieve larger particle sizes and improved compatibility, preventing polymer separation and resulting in a more homogeneous coating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large particle size silicone gum emulsions are used to improve haptic properties, then haptic performance is improved, but compatibility with polyurethane coating compositions deteriorates leading to pinholes and defects
Solution Approach 1:
The patent creates an interpenetrating polymer network (IPN) composite combining silicone gum and crosslinked organic polymer at the molecular level. This composite structure allows large particle size (1-10 microns) for haptic performance while the interlaced polymer networks prevent phase separation and improve compatibility with polyurethane coatings, eliminating pinholes and defects.
Solution Approach 2:
The patent changes the structural parameters of the emulsion by creating an IPN structure where two polymer networks are at least partially interlaced on a molecular scale. This structural transformation allows the emulsion to maintain large particle size for haptic properties while the crosslinked network structure improves stability and compatibility, preventing the harmful effects of particle aggregation and phase separation.
2Object-affected harmful factors
If silicone-acrylic copolymers are used to improve compatibility, then compatibility with polyurethane coatings is improved, but manufacturing complexity and cost increase due to copolymerization requirements
Solution Approach 1:
The patent segments the polymer structure into two separate but interpenetrating networks: a silicone gum network and a crosslinked organic polymer network. This segmentation avoids the need for complex copolymerization while achieving compatibility through the interlaced molecular structure, simplifying manufacturing compared to silicone-acrylic copolymers.
Solution Approach 2:
The crosslinked organic polymer acts as an intermediary between the silicone gum and the polyurethane coating composition. This intermediary network improves compatibility and stability without requiring direct copolymerization of silicone and acrylic, simplifying the manufacturing process while achieving the desired compatibility.
3Reliability
If polymer blends of silicones and polyacrylates are used to improve leather treatment performance, then performance attributes are improved, but polymer separation occurs during storage leading to poor distribution and coating defects
Solution Approach 1:
The patent creates an interpenetrating polymer network composite where silicone gum and crosslinked organic polymer are at least partially interlaced on a molecular scale. This composite structure fundamentally differs from simple polymer blends by creating a stable, integrated network that prevents phase separation during storage, ensuring uniform polymer distribution and eliminating coating defects.
Solution Approach 2:
The patent changes the physical-chemical parameters of the polymer mixture by introducing crosslinking to form an IPN structure. This parameter change transforms the system from a separable blend to a stable interlaced network, preventing polymer separation during storage while maintaining improved leather treatment performance.
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 IPN emulsions provide a more uniform distribution of polymers, reducing defects in leather coatings and enhancing performance attributes like haptics and compatibility, while simplifying the production process.
Implementation Method 1
an interpenetrating polymer network (IPN) of silicone gum and a crosslinked organic polymer... a polymer comprising two or more networks which are at least partially interlaced on a molecular scale but not covalently bonded to each other
Data Source
AI summary
An aqueous emulsion comprising particles having an average volume particle size (Dv 50) of 1 to 10 pm wherein the particles comprise an interpenetrating polymer network including from 90 to 99 wt % silicone gum and 1 to 10 wt % of crosslinked organic polymer, methods for making such aqueous emulsions, polyurethane coating compositions including such interpenetrating polymer networks, methods of preparing such polyurethane coating compositions, and their use in treating leather.