Water-Based Barrier Coating Resists Cracking on Fold
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Solution Overview
Problem
Existing barrier coating applications on paper and paperboard suffer from cracking on fold, leading to a loss of barrier properties, which is not effectively addressed by current technologies.
Innovation Solution
A water-based barrier coating composition comprising polyvinyl alcohol, a plasticizer, C16-C18 alkenyl ketene dimer, and a gelling agent, along with an aqueous polymer composition from an ethylenically unsaturated monomer blend, is used to form a grease barrier coating that is resistant to cracking on fold.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional barrier coatings are applied to paper and paperboard, then barrier properties are achieved, but cracking occurs on fold leading to loss of barrier properties
Solution Approach 1:
The patent modifies the chemical composition parameters of the coating by incorporating specific plasticizers and fatty acid amides in controlled amounts (0.1-5.0 wt% and 0.1-3.0 wt% respectively), which changes the physical properties of the coating film to improve flexibility and crack resistance while maintaining barrier properties
Solution Approach 2:
The patent creates a composite coating system combining polymer emulsion with specific additives (plasticizers, fatty acid amides, and optional waxes) that work synergistically to provide both barrier properties and flexibility, preventing the cracking that occurs with conventional single-component coatings
2Reliability
If polymer particles are packed tightly to form pinhole-free film, then barrier properties improve, but film flexibility decreases leading to cracking on fold
Solution Approach 1:
The patent adjusts the glass transition temperature parameter of the coating film by adding plasticizers, which maintains the pinhole-free structure while improving flexibility to prevent cracking during folding operations
Solution Approach 2:
The patent introduces plasticizers and fatty acid amides as intermediary substances that mediate between the rigid polymer matrix and the flexibility requirement, allowing the film to bend without cracking while maintaining its pinhole-free barrier structure
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 durable grease barrier coating that maintains its integrity on folding, preventing cracking and ensuring consistent barrier properties.
Implementation Method 1
Film formation proceeds from water evaporation and packing of polymer particles
Implementation Method 2
deformation of these particles due to capillary forces
Implementation Method 3
a) 0.1-5.0 wt% of a plasticizer and b) 0.1-3.0 wt% of a fatty acid amide
Data Source
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AI summary
Provided herein is a water-based barrier coating composition suitable for use as a barrier coating, said composition comprising (A): (i) 40 to 95 % by weight of the total weight of (A) an aqueous polymer composition obtainable by free radical (co)polymerizing an ethylenically unsaturated monomer blend comprising (a) 0 to 70 % by weight of at least one optionally substituted styrene, (b) up to 100 % by weight of at least one C1-C4-alkyl (meth)acrylate, (c) 0 to 10% by weight of other ethylenically unsaturated copolymerizable monomers, in the presence of (d) 0 to 40% % by weight of degraded starch having a molecular weight Mn of 500 to 10,000, wherein the sum (a)+(b)+(c)+(d) is 100%; (ii) 2 to 55 % by weight of the total weight of (A) of polyvinyl alcohol (PVA), optionally polymerized together with the components of (i); (iii) 2 to 30 % by weight of the total weight of (A) of a plasticizer; (iv) 5 to 30 % by weight of the total weight of (A) a composition comprising C16-C18 alkenyl ketene dimer, optionally as a mixture with rosin, whereby in the ratio of the C16-C18 alkenyl ketene dimer:rosin is from 100:0 to 25:75; (v) 5 to 20 % by weight of the total weight of (A) of a gelling agent; and (B): a filler.