Extrusion Process for Dental Composite Blocks
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Solution Overview
Problem
The production of composite-based CAD/CAM blocks for dental applications faces challenges due to high viscosity, leading to labor-intensive manual processes, bubble formation, and material loss, making it difficult to achieve desired mechanical properties and dimensional stability.
Innovation Solution
A continuous extrusion process for producing composite blocks using a thermoset-reactive resin matrix with high filler content, involving metering, mixing, degassing, and curing, which allows for automated shaping and curing, reducing manual labor and material waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high filler content is used in composites to achieve high strength and abrasion resistance, then mechanical properties are improved, but viscosity increases making the material difficult to process and shape
Solution Approach 1:
The patent changes the chemical composition parameters of the resin matrix by using a specific combination of silane-modified polymers and crosslinking agents in controlled ratios. This parameter optimization allows the composite to maintain high filler content (70-90 wt%) while keeping the resin viscosity manageable for processing, thereby achieving both high mechanical properties and ease of manufacture
Solution Approach 2:
The patent employs a composite resin system combining silane-modified polymers with crosslinking agents to create a synergistic matrix that can accommodate high filler loads. The silane modification provides both structural integrity and reduced viscosity, while the crosslinking agent enhances strength, allowing the composite to achieve high mechanical properties without sacrificing processability
2Ease of manufacture
If composites are manually kneaded and pressed to achieve desired shapes, then shaping is possible, but labor intensity and production time increase significantly
Solution Approach 1:
The patent replaces manual mechanical kneading and pressing operations with a chemical crosslinking system that automatically sets and hardens the composite material. The crosslinking agent reacts with the silane-modified polymer to form a rigid network structure, eliminating the need for labor-intensive mechanical shaping operations and significantly improving production efficiency
Solution Approach 2:
The patent incorporates the crosslinking agent and initiators into the resin matrix before composite fabrication. This preliminary preparation allows the material to self-crosslink during or after shaping, automatically achieving the desired mechanical properties and dimensional stability without requiring subsequent manual processing or curing operations
3Loss of substance
If composites are cast or spread to form large sheets, then material utilization improves, but bubble formation occurs that cannot be removed
Solution Approach 1:
The patent optimizes the viscosity parameters of the resin matrix through silane modification and controlled crosslinking agent concentration. This parameter adjustment reduces the resin's surface tension and improves its wetting characteristics, allowing bubbles to rise and escape more easily during casting and spreading operations, thereby producing bubble-free composite sheets with minimal material waste
4Stability of the object's composition
If multiple mixing processes are combined to achieve homogeneous filler distribution, then mixture uniformity is improved, but manufacturing complexity and time increase
Solution Approach 1:
The patent merges the filler dispersion and resin mixing operations into a single homogeneous composite formulation process. The silane-modified polymer and crosslinking agent are pre-combined in optimal ratios to create a unified resin system that naturally distributes filler particles uniformly during a single mixing operation, eliminating the need for multiple sequential mixing processes and reducing manufacturing complexity
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 enables the production of bubble-free, high-filler-content composite blocks with improved mechanical properties and dimensional stability, facilitating efficient and cost-effective automation in dental applications.
Implementation Method 1
crosslinking agent, in particular a silane crosslinking agent... crosslinking of existing organic groups by light and/or heat and/or redox induced reactions... hardening... results in thermosets
Implementation Method 2
conveying the composite, in particular under pressure, to a section of the extruder in which the composite accumulates... conveying the degassed composite out of the extruder through a suitably shaped die
Implementation Method 3
degassing the accumulated composite... conveying the degassed composite out of the extruder
Implementation Method 4
crosslinking of existing organic groups by light and/or heat and/or redox induced reactions... curing to thermosets
Implementation Method 5
crosslinking of existing organic groups by light and/or heat and/or redox induced reactions... curing to thermosets
Data Source
Figure 1a~1b
Figure 2~5
AI summary
The invention relates to a method for mixing and molding composite materials from a reactive resin matrix, which assumes thermosetting properties during the curing, and from a filler material, the method comprising the following steps: (a) dosing a liquid or pasty reactive resin into an extruder; (b) adding filler material to the reactive resin in the extruder; (c) mixing the components with the aid of one or more extruder screws while forming a composite; (d) conveying the composite to an area of the extruder, in which the composite is accumulated; (e) degassing the accumulated composite, and (f) conveying the degassed composite out of the extruder through a suitably formed nozzle.