Low Density Plaster Leveller for Textured Wallcoverings
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Solution Overview
Problem
Existing plaster levelling compositions fail to effectively obliterate the texture of wallcoverings without causing the wallcovering to bubble and peel away, due to their high density and water content, which redissolves the adhesive and leads to poor adhesion to polymer-coated papers.
Innovation Solution
A one-pack aqueous plaster levelling composition with a density of 0.3 to 1.2 g/cm³, comprising film-forming polymers, non-film-forming particles of varying densities, and water, specifically excluding particles derived from Perlite, which allows for a smooth surface without the issues of bubbling and peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If known plaster levelling compositions are used to fill textured wallcoverings, then the texture is obliterated and a smooth surface is provided, but the wallcovering rapidly begins to bubble and lift, eventually pulling away completely at the edges and finally peeling away from the wall
Solution Approach 1:
The patent changes the density parameter of the plaster composition from conventional high density (greater than 1.2 g/cm³) to low density (0.3 to 1.2 g/cm³). This parameter change reduces the weight of the plaster, minimizing the downward force that causes wallcovering detachment while still providing sufficient material for texture obliteration. The low density is achieved through the use of lightweight fillers such as expanded perlite, foam beads, or air-entraining agents.
Solution Approach 2:
The patent creates a composite plaster material combining calcium sulphate hemihydrate with lightweight fillers (expanded perlite, foam beads) and polymer modifiers. This composite structure provides both the levelling function and the reduced weight necessary to prevent wallcovering detachment. The polymer modifiers also enhance adhesion to the wallcovering surface.
2Quantity of substance
If high density plaster compositions are used, then the plaster provides sufficient weight and coverage, but the water content redissolves the adhesive causing the wallcovering to lift away
Solution Approach 1:
The patent reduces the density parameter of the plaster composition, which inherently reduces the water-to-plaster ratio. This parameter change limits the total water content available to redissolve the adhesive, while still providing adequate plaster material for coverage. The low density is achieved through the incorporation of hollow or highly porous particles that displace water without adding significant weight.
3Manufacturing precision
If conventional plaster formulations are applied to polymer-coated papers, then the plaster sets and provides a smooth surface, but the plaster adheres poorly and falls off the wallcovering
Solution Approach 1:
The patent develops a composite plaster formulation combining calcium sulphate hemihydrate with polymer modifiers specifically designed to enhance adhesion to polymer-coated surfaces. The polymer modifiers create chemical or physical bonds with the vinyl wallcovering, while the low density fillers provide the necessary bulk for smooth surface formation without compromising the adhesive bonds.
Solution Approach 2:
The patent modifies the chemical composition parameters of the plaster by incorporating specific polymer additives that improve wetting and bonding to polymer surfaces. This parameter change in composition enhances adhesion strength while maintaining the low density characteristics that prevent detachment.
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 provides a stable, non-bubbling, and non-peeling solution that effectively obliterates texture, maintaining adhesion and preventing detachment of the wallcovering, while being easier to apply and requiring fewer coats.
Implementation Method 1
On mixing with water, the hemihydrate hydrates to the dihydrate (CaSO4.2H2O) producing on evaporation of the excess water a crystalline three dimensional matrix
Implementation Method 2
producing on evaporation of the excess water a crystalline three dimensional matrix
Implementation Method 3
The composition is characterised in that it has a density from 0.3 to 1.2 g cm-3, more preferably from 0.4 to 1.0 g cm-3
Data Source
Figure 1
AI summary
Aqueous plaster leveller compositions of specified density, and their use to obliterate relief of textured wallcoverings, are disclosed. The compositions contain low density fillers such as hollow glass or polymeric microspheres and inorganic fillers and film forming binder.