Web-Formed Composite Coating Process for High Ash Content
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Solution Overview
Problem
Current methods for producing web-formed structures with high inorganic content face challenges such as unpredictable size variances, limitations in product dimensions, abrasive ceramic particles causing machine wear, and the use of non-renewable thermoplastic materials that degrade under sunlight and temperature changes, making it difficult to achieve a composite with both high mechanical strength and high mineral content.
Innovation Solution
A process involving a paper machine to produce a web-formed composite with an ash content of over 70% by applying multiple layers of a coating composition with high pigment content, preferably inorganic materials, onto a cellulose fiber base substrate, allowing for efficient production of a composite with enhanced mechanical strength, water resistance, and reduced energy consumption through controlled drying and porosity adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If ceramic fillers are dosed to the wet-end to produce preceramic papers with high ceramic content, then the inorganic material content increases, but filler retention deteriorates and process runnability worsens
Solution Approach 1:
The process is divided into two separate stages: (1) producing a cellulose web with controlled properties in the paper machine, and (2) coating the dried web with ceramic-containing slurry in a separate coating operation. This segmentation allows each stage to be optimized independently, avoiding the problems of dosing ceramic fillers to the wet-end while achieving high inorganic content in the final product.
Solution Approach 2:
The cellulose web is produced and dried to a controlled moisture content (5-15%) before the coating operation. This preliminary drying action creates an optimal substrate that readily absorbs the ceramic slurry coating, ensuring good filler retention and process runnability while achieving high ceramic content in the final composite.
2Quantity of substance
If ceramic particles are added to increase inorganic content, then the ash content increases, but machine wear increases due to abrasiveness
Solution Approach 1:
A cellulose web acts as an intermediary carrier that protects machine parts from direct contact with abrasive ceramic particles. The ceramic-containing slurry is applied as a coating on the soft cellulose substrate, which absorbs the mechanical stress and prevents ceramic particles from wearing down the coating head and other machine components.
Solution Approach 2:
The cellulose web provides a porous, compliant matrix that accommodates the abrasive ceramic particles without transmitting the mechanical stress to machine parts. The fibrous structure of the cellulose base substrate absorbs impact forces, reducing wear on the coating apparatus while maintaining high ceramic particle content in the final product.
3Strength
If thermoplastic materials are used to bind minerals, then the composite can be formed, but the material degrades under sunlight and temperature changes
Solution Approach 1:
The binding mechanism is changed from chemical bonding via thermoplastic polymers to physical bonding via moisture control. The cellulose web's natural hygroscopic properties are utilized to bind ceramic particles through hydrogen bonding and capillary forces, eliminating the need for thermoplastic materials that degrade under UV exposure and temperature variations.
Solution Approach 2:
A natural cellulose-ceramic composite is created that combines the renewable, UV-stable cellulose fibers with ceramic particles. This bio-based composite replaces fossil-fuel-derived thermoplastic binders, providing both composite formation and long-term stability under environmental conditions while being fully renewable and non-toxic.
4Quantity of substance
If multiple coating steps are applied to increase inorganic content, then the ash content increases, but the process complexity increases
Solution Approach 1:
The coating head is designed to perform multiple functions: it applies the ceramic-containing slurry coating, controls the moisture content of the substrate, and facilitates drying in a single integrated operation. This multi-functional design achieves high inorganic content through effective multi-layer coating without proportionally increasing process complexity.
Solution Approach 2:
The coating operation is designed to continuously apply multiple layers of ceramic-containing slurry in sequence, with each layer building upon the previous one. The process maintains continuous operation with optimized drying between layers, achieving high ash content through cumulative coating while minimizing interruptions and process complexity through streamlined workflow.
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 process enables the production of a moldable, high-density web-formed composite with over 70% ash content, offering improved mechanical strength, water resistance, and sustainability, suitable for various applications including 3D printing and ceramic production, while minimizing energy consumption and environmental impact.
Implementation Method 1
coating said base substrate with coating compositions comprising pigment materials of more than 50 wt% by weight in at least a first and a second coating step, so that at least two successive layers of coating is applied to said base substrate
Implementation Method 2
The process may further comprise drying of said composite to a final moisture content of below 4%
Data Source
AI summary
The invention relates to a process for producing a web formed composite with an ash content of more than 70 wt%. The inventive method comprises the steps of; providing a web-formed base substrate comprising fibers and coating said base substrate with coating compositions comprising pigment materials of more than 50 wt% by weight in at least a first and a second coating step, so that at least two successive layers of coating is applied to said base substrate. The process of the invention enables the production of a web-formed composite with a high mineral content in a fast and cost-efficient manner. The reinforcement base substrate provides the composite with mechanical strength. It has surprisingly been found that use of multiple coating in accordance with the invention makes it possible to produce a web formed composite with an ash content of more than 70%by weight. The invention further relates to a web formed composite produced by the method.