Thermally Restorable Adhesive Layer Thickness Control
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Solution Overview
Problem
High flowability of adhesive layers in thermally restorable articles leads to unstable shape formation during extrusion molding, resulting in increased thickness variation, particularly when the inner diameter is small, which complicates the process of increasing the diameter and achieving reliable adhesiveness.
Innovation Solution
Incorporating a thermoplastic resin with a melt flow rate of 15 g/10 min to 1,000 g/10 min at 190°C and an organically treated layered silicate to control shear viscosity, ensuring good flowability during extrusion molding while maintaining thickness consistency and enhancing adhesiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the adhesive layer has high flowability to achieve good filling property and adhesiveness, then the adhesiveness to base is improved, but the shape stability during extrusion molding deteriorates resulting in increased thickness variation
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive layer by incorporating specific polymers (polyolefin, polyamide, polyester) with defined molecular weight ranges and compositions. This allows control of flowability through chemical structure rather than单纯 viscosity adjustment, achieving good filling property while maintaining shape stability during extrusion molding.
Solution Approach 2:
The adhesive layer is formulated as a composite material containing multiple polymer components (polyolefin, polyamide, polyester) with specific weight ratios. This composite structure provides both the flowability needed for good filling and adhesiveness, and the structural stability required for consistent thickness during extrusion molding, resolving the contradiction between these two requirements.
2Reliability
If the adhesive layer has high flowability to easily closely adhere to adherend, then the filling property is improved, but the ease of manufacture deteriorates because the space inside may be filled and diameter increase process becomes difficult
Solution Approach 1:
The patent controls the flowability parameter through specific polymer selection and composition rather than using excessively low viscosity materials. This allows the adhesive to have sufficient flow to fill gaps and adhere well, while maintaining enough viscosity to prevent complete space filling during extrusion, thus keeping the diameter increase process manageable.
Solution Approach 2:
The adhesive layer is designed with specific local properties through polymer composition - having high flowability characteristics in the radial direction for good filling and adhesion, while maintaining structural integrity in the axial direction to prevent space filling and allow diameter increase. This directional quality differentiation resolves the manufacturing difficulty.
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 achieves a thermally restorable article with improved filling properties and reduced thickness variation of the adhesive layer, ensuring reliable adhesiveness and consistent extrusion moldability, even with small inner diameters.
Implementation Method 1
controlling a shear viscosity at a temperature of 150°C and at a shear rate of 0.1 s-1 to 10 Pa·s or less
Implementation Method 2
heating is then performed so that the outer layer of the tube is thermally shrunk and, at the same time, the inner adhesive layer is allowed to flow to fill a gap between the base to be treated and the outer layer
Data Source
Figure 1
AI summary
Provided is a thermally restorable article which has a good filling property when thermally shrunk to improve adhesiveness with a base to be treated, and in which the variation in the thickness of an adhesive layer during extrusion molding can be reduced. A multilayer thermally restorable article includes an adhesive layer composed of an adhesive composition that contains a thermoplastic resin having a melt flow rate of 15 g/10 min or more and 1,000 g/10 min or less at 190°C and at a load of 2.16 kg, and an organically treated layered silicate, and that has a shear viscosity of 1,000 Pa·s or more at a temperature of 150°C and at a shear rate of 0.1 s-1; and an outer layer disposed on an outer periphery of the adhesive layer. More preferably, a shear viscosity of the adhesive composition at a temperature of 150°C and at a shear rate of 100 s-1 is 200 Pa·s or less.