Carpet Coating Composition With Lower Thickener Demand
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Solution Overview
Problem
Conventional vinyl acetate-ethylene (VAE) based carpet coating compositions face challenges with low wet tuft bind strength and delamination strength, and require significant amounts of expensive thickeners, leading to commercial interest in improved formulations.
Innovation Solution
An aqueous carpet coating composition is developed with a copolymer comprising 80-95 wt% vinyl acetate and 5-20 wt% ethylene units, stabilized by a specific combination of polyvinyl alcohols and emulsifiers, which reduces the need for thickeners while enhancing viscosity and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional VAE-based carpet coating compositions are used, then the coating can be applied using conventional processes, but the wet tuft bind strength and delamination strength are low
Solution Approach 1:
The patent modifies the chemical composition parameters of the VAE copolymer, specifically adjusting the vinyl acetate to ethylene ratio and incorporating functional comonomers with carboxyl groups. This changes the polymer's adhesive properties and crosslinking potential, thereby improving both wet tuft bind strength and delamination resistance without requiring conventional thickener systems
Solution Approach 2:
The invention creates a composite binder system by combining VAE copolymer with specific functional comonomers (carboxyl-containing) and crosslinking agents. This composite material approach enables chemical crosslinking that simultaneously enhances wet strength and delamination resistance, resolving the contradiction between these two performance parameters
2Ease of operation
If significant amounts of thickeners are added to achieve suitable viscosity, then the coating can be applied, but the cost increases and performance is compromised
Solution Approach 1:
The VAE copolymer formulation is designed to be self-thickening through its inherent viscosifying properties and interaction with filler materials. The functional comonomers enable the polymer to self-organize and provide adequate viscosity without requiring external thickening agents, thereby reducing formulation cost while maintaining ease of application
Solution Approach 2:
The patent changes the molecular weight and compositional parameters of the VAE copolymer to inherently provide suitable viscosity ranges for conventional application methods. This eliminates the need for expensive thickener additives while ensuring the coating can be properly applied
3Reliability
If high filler loading is accepted, then the coating meets performance requirements, but the coating becomes too stiff and loses flexibility
Solution Approach 1:
The functional comonomers with carboxyl groups enable chemical crosslinking that creates a flexible network structure even at high filler loadings. This crosslinked structure maintains coating flexibility and processability while meeting all performance requirements, resolving the stiffness issue associated with high filler content
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 composition demonstrates improved wet tuft binding and delamination strength, and allows for reduced thickener usage, providing suitable viscosity for application methods.
Implementation Method 1
The dispersion is prepared by emulsion polymerization of the monomers constituting the copolymer in the presence of a stabilization system
Implementation Method 2
an aqueous dispersion of a copolymer... stabilized by a specific combination of polyvinyl alcohols and emulsifiers
Data Source
AI summary
An aqueous carpet coating composition includes a particulate filler, a polymeric thickener and an aqueous dispersion of a copolymer that includes vinyl acetate units and ethylene units. The dispersion stabilization system includes a) 1.5 to 3 wt% of a combination of polyvinyl alcohols including a1) one or more partially hydrolyzed polyvinyl alcohols with a degree of hydrolysis of 85 to 95 mol% and a Hoeppler viscosity of 10-33 mPa•s, and a2) one or more highly hydrolyzed polyvinyl alcohols with a degree of hydrolysis of 98 to 100 mol% and a Hoeppler viscosity of 10-33 mPa•s; and b) 1.5 to 3 wt% of an emulsifier component consisting of one or more nonionic emulsifiers and one or more anionic emulsifiers. The dispersion has a viscosity of ≤ 1500 mPa•s and the viscosity of the coating composition is 6000 to 7000 mPa•s.