Multilayer Lignocellulose Moulded Bodies with Formaldehyde Scavenger
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Solution Overview
Problem
Current lignocellulose-containing molded bodies face challenges in reducing formaldehyde emissions and improving mechanical properties, with existing methods either slowing down the hardening process or not fully addressing formaldehyde release issues.
Innovation Solution
A multilayer molded body design using a middle layer with formaldehyde resin or organic isocyanate as binder and a top layer with a polymer binder containing ethylenically unsaturated monomers and a formaldehyde scavenger, optimizing the binder composition to minimize formaldehyde emissions while maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If formaldehyde scavengers are added to aminoplast glue to reduce formaldehyde emissions, then formaldehyde emissions are reduced, but the glue hardens more slowly extending residence times in the hot press
Solution Approach 1:
The invention divides the binder system into multiple layers: the middle layer uses formaldehyde resin binder, while the top layers use formaldehyde-free binders (polymer A and polymer M). This segmentation isolates the formaldehyde-containing binder to the middle layer where it can be controlled, while the top layers provide the surface functionality without contributing to formaldehyde emissions. The top layer binder contains a formaldehyde scavenger that actively neutralizes any formaldehyde that might migrate to the surface.
Solution Approach 2:
The top layer acts as an intermediary barrier between the formaldehyde-containing middle layer and the external environment. The formaldehyde scavenger in the top layer binder serves as a chemical intermediary that captures and neutralizes formaldehyde molecules, preventing them from reaching the surface. This mediator approach allows the middle layer to use effective formaldehyde resin binders while the top layer protects against emissions.
2Object-affected harmful factors
If formaldehyde scavengers are added to aminoplast glue, then formaldehyde emissions are reduced, but the glue hardens more slowly extending residence times in the hot press
Solution Approach 1:
The binder system is segmented into middle layers with formaldehyde resin and top layers with formaldehyde-free polymers. This segmentation eliminates the need to add formaldehyde scavengers to the entire glue system, as only the top layers require formaldehyde-free composition. The middle layer can maintain its fast-hardening aminoplast binder without time extension, while the top layers provide emission control.
Solution Approach 2:
The invention extracts the formaldehyde scavenging function from the bulk glue system and places it specifically in the top layer binder. This allows the middle layer binder to maintain its original fast-hardening properties without modification, while the top layer provides the necessary formaldehyde emission control. The scavenger is taken out of the critical hardening zone and placed in the protective surface zone.
3Strength
If conventional single-layer design with formaldehyde resin binder is used, then mechanical strength is achieved, but formaldehyde emissions occur
Solution Approach 1:
The molding is divided into multiple layers with different binder compositions. The middle layers use formaldehyde resin binders that provide excellent mechanical strength and bonding. The top layers use formaldehyde-free polymer binders that provide emission control while maintaining surface integrity. This segmentation allows each layer to optimize for its specific function.
Solution Approach 2:
The invention uses a composite binder system combining formaldehyde resin (for strength) with formaldehyde-free polymers (for emission control). The top layer binder is a composite of polymer A (polyacrylic acid or polyacrylamide) and polymer M (polymer with epoxide or hydroxyalkyl groups), creating a material that provides both structural integrity and formaldehyde emission control.
4Object-affected harmful factors
If top layer uses formaldehyde-free polymer binder, then formaldehyde emissions are reduced, but mechanical strength and moisture resistance need optimization
Solution Approach 1:
The top layer binder is designed as a composite system combining polymer A (polyacrylic acid or polyacrylamide) with polymer M (containing epoxide or hydroxyalkyl groups). This composite provides enhanced mechanical strength and moisture resistance through the synergistic interaction of the two polymers, while maintaining formaldehyde-free composition. The crosslinking capability of polymer M enhances the overall strength.
Solution Approach 2:
The invention specifies precise compositional parameters for the top layer binder: polymer A at 70-100 wt% and polymer M at 0-30 wt%, with molecular weight and functional group specifications. These parameter controls ensure that the formaldehyde-free top layer achieves the necessary mechanical strength and moisture resistance while maintaining emission control.
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 solution significantly reduces formaldehyde emissions and enhances mechanical properties such as transverse tensile strength and moisture resistance, allowing for faster production times and improved performance in lignocellulose-containing molded bodies.
Implementation Method 1
contains a formaldehyde scavenger
Implementation Method 2
a polymer A which is composed of the following monomers: a) 80 to 100% by weight of at least one ethylenically unsaturated mono- and/or dicarboxylic acid
Implementation Method 3
a low molecular weight crosslinker with at least two functional groups which are selected from the group hydroxy, Carboxylic acid and its derivatives, primary, secondary and tertiary amine, epoxy, aldehyde, an organic isocyanate
Data Source
AI summary
A multilayer lignocellulose-containing molding comprising A) a middle layer or a plurality of middle layers comprising lignocellulose-containing particles which is/are obtainable by using a binder (a) and B) a covering layer or a plurality of covering layers comprising lignocellulose-containing particles which is/are obtainable by using a binder (b), the binder (a) being selected from the group consisting of (a1) formaldehyde resins and (a2) an organic isocyanate having at least two isocyanate groups; the binder (b) comprising the following components: an aqueous component (I) comprising (i) a polymer A which is composed of the following monomers: a) from 70 to 100% by weight of at least one ethylenically unsaturated mono- and/or dicarboxylic acid (monomer(s) A1) and b) from 0 to 30% by weight of at least one further ethylenically unsaturated monomer which differs from the monomers A1 (monomer(s) A2) optionally (ii) a low molecular weight crosslinking agent having at least two functional groups which are selected from the group consisting of hydroxyl, carboxyl and derivatives thereof, primary, secondary and tertiary amine, epoxy, aldehyde, an organic isocyanate having at least two isocyanate groups as component (II) and, optionally, a component (III), as an aqueous dispersion, comprising one or more polymer(s) M which is/are composed of the following monomers: a) from 0 to 50% by weight of at least one ethylenically unsaturated monomer which comprises at least one epoxide and/or at least one hydroxyalkyl group (monomer(s) M1) and b) from 50 to 100% by weight of at least one further ethylenically unsaturated monomer which differs from the monomers M1 (monomer(s) M2) and, optionally, customary additives as component (IV), and the binder (b) optionally comprises a formaldehyde scavenger.