Water-Based Coating Composition for Paper Substrates
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Solution Overview
Problem
Current water-resistant coatings for the paper industry, such as wax coatings, are expensive, non-recyclable, and environmentally unfriendly, and alternative coatings face issues like delamination, edge wicking, and difficulties in fluting and gluing.
Innovation Solution
A wet coating composition comprising an oxidized paraffin/polyethylene wax emulsion and an ethylene/acrylic based copolymer wax emulsion, with a dispersant, applied to cellulosic fiber-based substrates to provide a water-resistant barrier while maintaining recyclability and environmental friendliness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hot melt wax coatings are used to provide water resistance, then water barrier performance is improved, but cost increases and environmental friendliness deteriorates due to non-recyclability
Solution Approach 1:
The invention changes the chemical composition parameters of the coating from traditional hydrophobic waxes to a water-based emulsion containing oxidized paraffin/polyethylene wax and ethylene/acrylic copolymer. This parameter change maintains water barrier performance through controlled surface energy (20-60 mN/m) while enabling recyclability and environmental compatibility through water-based formulation
Solution Approach 2:
The invention uses a composite coating system combining oxidized paraffin/polyethylene wax (for water resistance) with ethylene/acrylic copolymer (for adhesion and surface properties). This composite approach achieves the water barrier performance of traditional waxes while adding functionality for recyclability and reduced environmental impact
2Object-generated harmful factors
If alternative recyclable coatings are used instead of wax coatings, then environmental friendliness is improved, but manufacturing precision deteriorates due to delamination during corrugation and fluting
Solution Approach 1:
The invention optimizes the surface energy parameters of the coating to range from 20-60 mN/m, with the oxidized paraffin/polyethylene wax contributing less than 25 mN/m substantially from dispersive energy. This parameter control ensures adequate adhesion to paper substrates during corrugation and fluting while maintaining recyclability
Solution Approach 2:
The composite system combines oxidized paraffin/polyethylene wax (providing water resistance and surface energy control) with ethylene/acrylic copolymer (providing adhesion and flexibility). This combination maintains coating integrity during manufacturing processes like corrugation and fluting while preserving environmental friendliness
3Object-generated harmful factors
If alternative recyclable coatings are used, then environmental friendliness is improved, but reliability deteriorates due to edge wicking and water penetration through vent holes
Solution Approach 1:
The invention carefully controls the surface energy parameters, with the oxidized paraffin/polyethylene wax providing less than 25 mN/m substantially from dispersive energy, and the final coating achieving 20-60 mN/m total surface energy. This parameter optimization creates adequate hydrophobicity to prevent edge wicking and water penetration while maintaining recyclability
Solution Approach 2:
The composite of oxidized paraffin/polyethylene wax and ethylene/acrylic copolymer creates a coating that balances hydrophobicity (from the wax) and adhesion (from the copolymer). This balance prevents edge wicking and water penetration through vent holes while preserving environmental friendliness
4Object-generated harmful factors
If alternative recyclable coatings are used, then environmental friendliness is improved, but ease of operation deteriorates due to difficulties in gluing
Solution Approach 1:
The invention optimizes the surface energy of the final coating to range from 20-60 mN/m, with controlled dispersive and polar components. This parameter range provides adequate surface energy for adhesive bonding (gluing) while maintaining the water-resistant and environmentally friendly properties of the coating
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 coating composition achieves effective water resistance, prevents edge wicking, and allows for easy gluing and fluting, while being recyclable and environmentally friendly, comparable to traditional wax coatings but with improved properties.
Implementation Method 1
a first aqueous emulsion of an oxidized paraffin/polyethylene wax; wherein the oxidized paraffin/polyethylene wax has a surface energy less than or equal to 25 mN/m being substantially dispersive energy
Implementation Method 2
the wet coating composition when dried forms a coating having a surface energy ranging from 20 to 60 mN/m being the sum of dispersive and polar energies
Data Source
AI summary
A wet coating composition useful for coating a cellulosic fiber-based substrate is provided. The composition includes two aqueous emulsions. The first emulsion includes an oxidized paraffin/polyethylene wax and the second emulsion includes an ethylene/acrylic acid copolymer wax, ethylene/acrylic amide copolymer wax, ethylene/acrylic acid/acrylic amide copolymer wax or a mixture thereof. The oxidized paraffin/polyethylene wax has a surface energy less than or equal to 25 mN/m being substantially dispersive energy. The wet coating composition when dried forms a coating having a surface energy ranging from 20 to 60 mN/m being the sum of dispersive and polar energies. A process for treating a cellulosic fiber-based substrate with the wet coating composition, a substrate coated and articles including the coated substrate are also described. The process involves a heating step to allow migration of the coating towards a core of the cellulosic fiber-based substrate.