Cardboard Coating Binder Composition for Delamination Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing coating solutions for multi-layer cardboard fail to prevent delamination and picking during printing, which affects the strength and smoothness of the coated surface.
Innovation Solution
A coating slip comprising an aqueous dispersion of vinyl acetate polymers and styrene copolymers, specifically formulated with a weight ratio of 77:23 to 93:7, along with inorganic pigments and auxiliary materials, to enhance the bonding strength and resistance to delamination and picking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coating slips are used on multi-layer cardboard, then the coating can be applied, but delamination occurs during printing due to tensile forces in the z-direction
Solution Approach 1:
The invention uses a composite binder system combining vinyl acetate polymer and styrene copolymer in specific weight ratios (30-70 wt% vinyl acetate polymer with 70-30 wt% styrene copolymer). This composite material approach creates synergistic effects where the vinyl acetate polymer provides flexibility and adhesion to prevent delamination, while the styrene copolymer contributes to surface strength and resistance to picking, resolving the contradiction between delamination resistance and bonding strength.
Solution Approach 2:
The invention optimizes specific parameters including the weight ratio of binder components (30-70 wt% vinyl acetate polymer), ethylene content (1-13 wt%), and glass transition temperature (10-30°C). These parameter changes tailor the binder's mechanical properties to withstand the tensile forces during printing while maintaining strong adhesion to the multi-layer cardboard structure, preventing both delamination and picking.
2Strength
If the coating provides good adhesion to prevent picking, then surface strength improves, but the rough fibrous surface of cardboard limits printability
Solution Approach 1:
The invention creates different local properties within the coating layer by using the dual-polymer binder system. The vinyl acetate polymer component provides flexibility and conformability to the rough cardboard surface, enabling good coverage and adhesion. The styrene copolymer component provides surface hardness and strength for pick resistance. This local differentiation of properties within the coating allows the coating to adapt to the rough substrate while providing a smooth, printable surface with high strength.
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 delamination and picking, resulting in improved surface strength and printability of multi-layer cardboard, ensuring high dry picking resistance and smooth coating.
Implementation Method 1
an aqueous dispersion of one or more vinyl acetate polymers, obtainable by radically initiated emulsion polymerization
Implementation Method 2
enhance the bonding strength and resistance to delamination and picking
Implementation Method 3
aqueous dispersion of vinyl acetate polymers and styrene copolymers
Data Source
AI summary
The invention relates to a coating composition comprising (i) an aqueous dispersion of one or more vinyl acetate polymers, obtainable by radical-initiated emulsion polymerization of 77 to 99 wt.% vinyl acetate, 1 to 13 wt.% ethylene, and 0 to 10 wt.% one or more monoethylene unsaturated monomers, which is neither vinyl acetate nor ethylene, wherein the amounts of the monomers add up to 100 wt.%, (ii) an aqueous dispersion of one or more styrene copolymers, obtainable by radical-initiated emulsion polymerization of a monomer composition comprising 35 to 70 wt.% styrene, 20 to 60 wt.% one or more esters of acrylic and/or methacrylic acid with alkanols having 1 to 12 carbon atoms, or one or more conjugated aliphatic dienes, and 1 to 10 wt.% monomers containing one or more acid groups, wherein the amounts of Monomers per 100 wt.(iii) inorganic pigments and (iv) optionally further excipients, wherein the total amount of the emulsion polymers (i) and (ii) is 10 to 30 parts by weight based on 100 parts by weight of inorganic pigment (iii) and wherein the weight ratio of the styrene copolymer to the vinyl acetate polymer is 77:23 to 93:7, as well as a process for producing the coating, its use for coating cardboard, a process for coating cardboard with the coating and the cardboard coated therewith.