Calendering Cellulose Ester Films via Melt Processing
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Solution Overview
Problem
The production of cellulose ester films and sheets is limited by the need for extra compounding steps to convert powder forms into melt extrudable forms, leading to increased costs, variability, and degradation, particularly with standard extrusion methods that require higher temperatures and plasticizer modification.
Innovation Solution
A composition comprising cellulose esters with specific (C2-5)alkanoyl and hydroxyl substituents, plasticizers, roll release agents, and processing aids, allowing for calendering processes that reduce processing steps and temperatures, enabling the production of uniform films and sheets with improved quality and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard extrusion methods are used to produce cellulose ester films, then the material can be processed, but extra compounding steps are required to convert powder form into melt extrudable form, increasing cost and complexity
Solution Approach 1:
The patent combines the compounding step with the main extrusion process by incorporating plasticizer and processing aid directly into the extruder feed. This merging eliminates the separate pre-compounding step required by conventional methods, reducing both process complexity and manufacturing cost while maintaining proper material flow characteristics.
Solution Approach 2:
The patent performs preliminary blending of the cellulose ester powder with plasticizer and processing aid before extrusion. This preliminary action ensures the material is properly prepared for extrusion without requiring a separate compounding step during production, thereby simplifying the overall manufacturing process.
2Ease of operation
If standard extrusion methods are used with higher temperatures, then the material flows better, but degradation and plasticizer loss increase
Solution Approach 1:
The patent modifies the chemical composition parameters by selecting specific cellulose esters with degree of substitution between 2.0 and 3.0 and incorporating particular plasticizers and processing aids. These parameter changes enable the material to flow properly at lower extrusion temperatures, preventing degradation and plasticizer loss while maintaining good flow characteristics.
Solution Approach 2:
The patent creates a composite material system combining cellulose ester with specific plasticizers and processing aids. This composite formulation improves flow characteristics at lower temperatures, reducing thermal degradation while maintaining processability, thereby enhancing product quality and reliability.
3Ease of operation
If cellulose esters are produced in powder form, then the material is easier to handle, but an extra compounding step is required to convert to melt extrudable form
Solution Approach 1:
The patent merges the compounding operation with the extrusion process by feeding plasticizer and processing aid directly into the extruder along with the powder cellulose ester. This eliminates the separate compounding step, maintaining the handling advantages of powder form while improving production efficiency by reducing the number of process steps.
4Productivity
If calendering is used instead of extrusion, then processing steps can be reduced and costs lowered, but very few materials besides PVC have the right combination of processing window, flow characteristics and metal release
Solution Approach 1:
The patent selects cellulose esters with specific parameters (degree of substitution 2.0-3.0, specific glass transition temperatures) and combines them with particular plasticizers and processing aids. These parameter changes give the material calendering-compatible flow characteristics and metal release properties, expanding the range of materials suitable for calendering beyond just PVC.
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 described composition enables the production of cellulose ester films and sheets through calendering, reducing costs and variability while maintaining quality by optimizing the degree of substitution, crystallinity, and melt viscosity, thus overcoming the limitations of traditional extrusion methods.
Implementation Method 1
the cellulose ester has a glass transition temperature from about 80° C. to about 200° C.
Implementation Method 2
running at a lower temperature, better quality and lower cost film can be produced by calendering
Data Source
AI summary
This invention relates to cellulose ester compositions cable of being calendered. The invention also relates to calendered films or sheets comprising the cellulose ester compositions and processes for calendering the cellulose compositions.