Nano-coated Pulp Substrate Barrier Process
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Solution Overview
Problem
Existing methods for manufacturing pulp-based substrates with barrier and strength properties face challenges such as water sensitivity, dimensional instability, and the need for high coat weights, which can lead to environmental issues and recycling problems due to the use of materials like aluminum foil.
Innovation Solution
A process involving a suspension of pulp with a high Schopper Riegler value, forming a wet web, dewatering and drying, followed by the application of an acrylic monomer solution with low water content and radiation curing, and finally, a nano-coating with a thickness ranging from 0.1 nm to 100 nm to achieve enhanced barrier properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water-based solutions or dispersions are applied onto thin substrates to provide barrier properties, then barrier properties are improved, but web breaks and dimensional instability occur due to water sorption and penetration into the hydrophilic substrate
Solution Approach 1:
The patent changes the fundamental parameter of the coating medium from water-based to solvent-free acrylic monomer solution. This eliminates water sorption and penetration issues that cause dimensional instability, while still providing the necessary barrier properties through the cured polymer layer and subsequent nano-coating.
Solution Approach 2:
The patent extracts and removes water from the coating system entirely. By using a solvent-free acrylic monomer solution, the harmful effect of water penetration into the hydrophilic substrate is eliminated, preventing web breaks and dimensional changes while maintaining barrier functionality.
2Reliability
If aluminum foil or film-forming polymers are used to provide barrier properties, then barrier and water vapor barrier properties are improved, but environmental challenges and recycling problems arise
Solution Approach 1:
The patent changes the material composition from conventional aluminum foil or fossil-based polymers to a cellulose-based substrate with an acrylic monomer coating and nano-coating. This maintains the barrier properties while eliminating the environmental harm associated with aluminum and fossil fuels, enabling compostability and recyclability.
Solution Approach 2:
The patent creates a composite structure combining cellulose substrate, acrylic monomer coating layer, and nano-coating (such as metal oxides or ceramics). This composite provides the necessary barrier properties against water vapor and gases while being environmentally friendly and suitable for composting and recycling, replacing traditional aluminum or plastic barriers.
3Object-affected harmful factors
If the solids content of the applied solution is increased to reduce water content, then water-related problems are reduced, but coat weight and viscosity increase
Solution Approach 1:
The patent extracts water from the coating system entirely by using a solvent-free acrylic monomer solution. This eliminates the need to balance water content with solids content, avoiding the problem of increased coat weight and viscosity that would result from using high-solids water-based alternatives.
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
This process effectively achieves advantageous barrier properties, particularly water vapor barrier properties, while maintaining substrate strength and being environmentally friendly by minimizing the use of non-renewable materials and ensuring recyclability.
Implementation Method 1
adding a first layer of an acrylic monomer solution comprising less than 2 wt-% water to the surface of the substrate, followed by radiation curing the first layer
Implementation Method 2
providing a nano-coating on the surface of the cured first or second layer such that a nano-coating having a thickness in the range of from 0.1 nm to 100 nm is provided on the substrate
Data Source
AI summary
The present invention is directed to a process for manufacturing a nano-coated pulp-based substrate comprising the steps of: a) providing a suspension comprising pulp, said pulp having Schopper Riegler value of at least 70°; b) using the suspension of step a) to form a wet web; c) dewatering and/or drying the wet web to form a substrate; d) adding a first layer of an acrylic monomer solution comprising less than 2 wt-% water to the surface of the substrate, followed by radiation curing the first layer; e) optionally adding a second layer comprising an acrylic monomer solution to the surface of the cured first layer and radiation curing the second layer; f) providing a nano-coating on the surface of the cured first or second layer such that a nano-coating having a thickness in the range of from 0.1 nm to 100 nm is provided on the substrate.