Microfibrillated Cellulose–Metal Adhesives for Faster Board Processing
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Solution Overview
Problem
Existing adhesive compositions used in manufacturing corrugated and solid boards face challenges with boron-containing cross-linkers like borax and boric acid, which are toxic, hazardous, and environmentally unfriendly, leading to issues such as delamination, low tack, and unsatisfactory processing speeds.
Innovation Solution
A combination of microfibrillated cellulose (MFC) and a metal in an oxidation state of II or greater is used to replace boron-containing cross-linkers, providing improved adhesive properties and processing speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If boron-containing cross-linkers (borax, boric acid) are used to improve adhesive bonding and curing, then adhesion strength is improved, but toxicity and environmental harm increase
Solution Approach 1:
The invention extracts and removes the harmful boron-containing cross-linkers (borax, boric acid) from the adhesive composition while maintaining the essential cross-linking function through alternative means. The patent explicitly eliminates these toxic substances from the formulation to resolve the contradiction between adhesion strength and environmental safety.
Solution Approach 2:
The invention introduces microfibrillated cellulose (MFC) as an intermediary substance that mediates the cross-linking process. MFC acts as a natural, non-toxic alternative to boron-based cross-linkers, providing the necessary adhesive bonding and curing functionality without the harmful effects of borax and boric acid.
2Object-affected harmful factors
If borax is replaced by MFC alone, then environmental safety is improved, but glue-ability and gelatinization speed deteriorate
Solution Approach 1:
The invention creates a composite adhesive system combining multiple components: starch or PVA as the base adhesive, microfibrillated cellulose (MFC) as the primary cross-linking agent, and additional cross-linkers (glutaraldehyde, formaldehyde, or metal salts) to enhance gelatinization speed and glue-ability. This composite approach maintains environmental safety while restoring productivity.
Solution Approach 2:
The invention modifies the chemical and physical parameters of the adhesive system by introducing specific cross-linking agents that accelerate gelatinization. The use of aldehydes or metal salts in controlled amounts adjusts the curing kinetics and adhesive properties without compromising the environmentally friendly nature of the formulation.
3Object-affected harmful factors
If PVA-based adhesive compositions replace boric acid, then environmental safety is improved, but initial tack deteriorates
Solution Approach 1:
The invention adjusts the chemical composition and concentration parameters of the PVA-based adhesive system. By optimizing the ratio of PVA to MFC and selecting appropriate cross-linking agents, the formulation achieves sufficient initial tack while maintaining environmental safety. The cross-linking density and network structure are tuned to provide adequate adhesion strength.
Solution Approach 2:
The invention develops a composite PVA-MFC-adhesive system that combines the benefits of PVA (environmental compatibility) with MFC (cross-linking capability) and supplemental cross-linkers (tack enhancement). This multi-component composite material achieves both environmental safety and satisfactory initial tack 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 combination achieves enhanced initial tack, adhesion, and processing speeds on corrugated board production lines, resulting in a sustainable and environmentally friendly adhesive composition.
Implementation Method 1
a cross-linker is commonly used to improve curing and bonding between the molecules of the composition and with the substrate
Implementation Method 2
has at least two groups available for hydrogen bonding, preferably OH groups
Data Source
AI summary
The present invention relates to an adhesive composition comprising, among others, (i) microfibrillated cellulose and (ii) a metal in oxidation state of II or greater. The present invention further relates to uses of such an adhesive composition and to products prepared with such an adhesive composition. Furthermore, the present invention relates to a process for making corrugated paperboards or cardboards, or solid paperboards or cardboards by using such an adhesive composition.