Cellulose Ether Additives for Ceramic Extrusion Pressure
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Solution Overview
Problem
The extrusion of ceramic masses and other sinterable materials often faces high extrusion pressures, leading to premature equipment wear and high power costs, along with low extrusion rates and potential cracking due to internal friction and shrinkage issues during the baking or sintering process.
Innovation Solution
Incorporating specific water-soluble cellulose ethers with defined rheological properties, such as a loss modulus to storage modulus ratio (tan δ) of less than 1.3 and a capillary breakup time of 2.0 seconds or more, into ceramic masses to reduce friction and improve extrusion efficiency without cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional extrusion methods are used for ceramic masses, then extrusion can be performed, but high extrusion pressures cause premature equipment wear and high power costs
Solution Approach 1:
The patent applies parameter changes by modifying the rheological properties of the ceramic mass through the addition of specific cellulose ethers. The cellulose ethers are selected to achieve a tan δ value of less than 1.3 at 100 rad/s, which changes the flow behavior and reduces extrusion pressure. This parameter modification resolves the contradiction by enabling extrusion at lower pressures while maintaining material integrity.
Solution Approach 2:
The cellulose ether acts as an intermediary substance that modifies the interaction between ceramic particles and the extrusion environment. It serves as a rheological modifier that mediates the flow characteristics, reducing friction and pressure during extrusion while preventing crack formation. This intermediary substance resolves the equipment wear issue without compromising the ceramic mass properties.
2Productivity
If conventional extrusion methods are used for ceramic masses, then extrusion can be performed, but low extrusion rates reduce plant capacity
Solution Approach 1:
The patent utilizes parameter changes by optimizing the cellulose ether concentration and molecular characteristics to achieve favorable rheological parameters. The tan δ < 1.3 condition at 100 rad/s creates an optimal balance between flowability and structural stability, enabling higher extrusion rates without requiring excessive pressure. This resolves the productivity-pressure contradiction.
3Temperature
If ceramic masses are extruded, then production can proceed, but internal friction causes excessive heating requiring cooling water or electric cooling
Solution Approach 1:
The patent applies parameter changes by selecting cellulose ethers that modify the friction characteristics of the ceramic mass. The rheological optimization (tan δ < 1.3) reduces internal friction during extrusion, thereby minimizing viscous heating. This resolves the contradiction by reducing temperature rise without requiring additional cooling energy.
4Reliability
If ceramic masses are extruded, then profiles can be produced, but cracks form during drying and subsequent baking or sintering
Solution Approach 1:
The cellulose ether serves as an intermediary that modifies the stress distribution within the ceramic mass during drying and sintering. It acts as a binding agent that maintains structural integrity during shrinkage, preventing crack formation. This resolves the reliability-stress contradiction by enabling the mass to withstand shrinkage stresses without cracking.
Solution Approach 2:
The patent applies beforehand cushioning by incorporating cellulose ethers that provide preliminary structural support to the ceramic mass. This cushioning effect is established before drying and sintering, allowing the mass to withstand subsequent shrinkage stresses without developing cracks. The rheological modification creates a more resilient structure that anticipates and withstands future stress.
5Shape
If thin webs are extruded, then fine structures can be produced, but particle cohesion must be very high to prevent problems
Solution Approach 1:
The patent applies parameter changes by optimizing the cellulose ether properties to achieve enhanced particle cohesion. The rheological modification creates stronger interparticle bonds, enabling the extrusion of thin webs without compromising structural integrity. This resolves the contradiction between achieving thin geometries and maintaining sufficient 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 use of these cellulose ethers significantly reduces extrusion pressures, maintains low heating, and minimizes cracking, enabling the production of ceramic honeycomb bodies with enhanced extrusion rates and plant capacity while maintaining material cohesion.
Implementation Method 1
an alkaline solution of 1.0 part by weight of these cellulose ethers per 100 parts by weight of solution displays elastic properties in which the ratio of loss modulus G'' to storage modulus G' (tan δ=G''/G') of the solution at a temperature of 20°C.+/−1°C. when using a solvent comprising 98 parts by weight of water and 2 parts by weight of sodium hydroxide per 100 parts by weight of solvent in a rheological oscillation experiment as a function of the angular frequency ω in the linear viscoelastic region
Implementation Method 2
an alkaline solution of 1.5 parts by weight of the cellulose ethers per 100 parts by weight of solution has a capillary breakup time in an extensional flow experiment at a temperature of 20°C.+/−1°C. when using a solvent comprising 98 parts by weight of water and 2 parts by weight of sodium hydroxide per 100 parts by weight of solvent of 2.0 or more seconds
Data Source
AI summary
The present invention relates to extrudable ceramic masses and other masses which set as a result of baking or sintering, which masses comprise specific additives based on water-soluble cellulose ethers, an extrusion process, the extrudates and their use.