Spinal Fixation Rod Resin Bonding Strength
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Solution Overview
Problem
Existing metal fixture rods for spinal fixation are susceptible to magnetic field interference during MRI imaging, causing image disturbances, while polymer-based rods face challenges in achieving uniform and stable bonding between the core and the covering layer.
Innovation Solution
A fixture rod comprising a core member made of resin with a reinforcing fiber layer, where the resins in both layers have a critical surface tension of 20 mN/m or more, and the fiber layer is bonded to the core member with recesses formed on the core member's surface to enhance bonding area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal is used as fixture rod material, then fixing force and strength are improved, but magnetic field interference occurs during MRI imaging causing image disturbance
Solution Approach 1:
The patent replaces traditional metal fixture rods with polymer-based rods that have sufficient strength for spinal fixation without magnetic interference properties. The polymer material, while having different mechanical characteristics than metal, provides adequate fixing force for the application while being completely non-magnetic, thus eliminating MRI imaging disturbances.
Solution Approach 2:
The patent employs composite material structure consisting of a polymer core member reinforced with a fiber layer (carbon fiber, glass fiber, or aramid fiber). This composite construction provides enhanced mechanical strength and rigidity comparable to metal rods while maintaining the non-magnetic property essential for MRI compatibility. The fiber reinforcement compensates for the lower inherent strength of polymer materials.
2Strength
If adhesive is used for bonding between polymer core material and covering layer, then bonding is achieved, but uniform bonding is difficult to reliably achieve
Solution Approach 1:
The patent incorporates recesses on the surface of the core member before the fiber layer is applied. These pre-formed recesses create mechanical interlocking features that ensure uniform bonding across the entire interface between the core and fiber layer, eliminating the reliability issues associated with adhesive-only bonding methods.
Solution Approach 2:
The patent uses a composite bonding approach combining chemical bonding (adhesive) with mechanical bonding (recesses providing physical interlocking). This dual bonding mechanism ensures uniform and reliable bonding between the core member and fiber layer, overcoming the limitations of adhesive-only methods where uniform bonding is difficult to achieve.
3Object-affected harmful factors
If polymer core material is used instead of metal, then magnetic field interference is avoided, but bonding strength between core material and covering layer deteriorates
Solution Approach 1:
The patent creates a composite structure with a polymer core member and a reinforcing fiber layer (carbon fiber, glass fiber, or aramid fiber). This composite construction maintains the non-magnetic property of the polymer while significantly enhancing the overall bonding strength and mechanical properties through the high-strength fiber reinforcement.
Solution Approach 2:
The patent pre-forms recesses on the core member surface to create mechanical interlocking features before applying the fiber layer. This preliminary action ensures strong and uniform bonding between the core and covering layer, compensating for the inherently lower bonding strength of polymer materials compared to metal.
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 solution provides excellent bonding strength between the core material and the reinforcing fiber layer, along with high rigidity and durability against deformation loads, while avoiding magnetic interference issues.
Implementation Method 1
the resin of the core member and the resin of the reinforcing fiber layer are the same resin, or the resin of the core member and the resin of the reinforcing fiber layer are different resins, and a critical surface tension of each of the resin of the core member and the resin of the reinforcing fiber layer is 20 mN/m or more
Data Source
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AI summary
Provided is a fixture rod that is excellent in bonding strength between a core material and a reinforcing fiber layer and has high rigidity and high durability against a deformation load. A fixture rod according to one embodiment of the present invention comprises: a core member containing a resin; and a reinforcing fiber layer provided on the core member, and is configured such that the resin of the core member and a resin of the reinforcing fiber layer are the same resin, or the resin of the core member and the resin of the reinforcing fiber layer are different resins, and a critical surface tension of each of the resin of the core member and the resin of the reinforcing fiber layer is 20 mN/m or more.