Flame-Retardant Polyamide Sheathing for Optical Cables
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Solution Overview
Problem
Existing polyamide sheathings for optical fibers and cables do not adequately meet the requirements for both indoor and outdoor applications, particularly lacking in flame retardancy and flexibility, with previous materials not being halogen-free and not effectively protecting against weather and rodent damage.
Innovation Solution
A flame-retardant polyamide molding compound with a specific composition of 40-71% copolyamide MACMI/12, 20-51% aliphatic polyamide, 6-20% melamine cyanurate, 3-10% aryl phosphate, and 0-6% further additives, which forms one or more layers of the casing, providing a Shore hardness of at least 77 and passing the V2 rating in the 50 W vertical fire test, while allowing for flexibility and rodent resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polyamide sheathings are used, then basic protective function is provided, but flame retardancy and halogen-free requirements are not met
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating specific flame retardant compounds (melamine cyanurate and aryl phosphate) in defined weight percentages (6-20% and 3-10% respectively) to achieve flame retardancy while maintaining halogen-free status. This parameter modification transforms the material properties to meet both safety requirements.
Solution Approach 2:
The patent creates a composite molding compound by combining copolyamide MACMI/12 with aliphatic polyamide and integrating flame retardant additives (melamine cyanurate and aryl phosphate) into the polyamide matrix. This composite structure achieves flame retardancy without halogens, resolving the contradiction between reliability and harmful factors.
2Object-affected harmful factors
If robust protective sheathings are used for outdoor applications, then weather and rodent protection is improved, but flexibility and bendability are reduced
Solution Approach 1:
The patent modifies the physical parameters of the sheathing by specifying Shore hardness within the range of 77-95 and controlling the composition ratios of copolyamide MACMI/12 (40-71%) and aliphatic polyamide (20-51%). These parameter changes achieve the optimal balance between rodent/weather resistance and flexibility, allowing the material to pass buckling tests while maintaining protective properties.
Solution Approach 2:
The patent uses a composite material system combining copolyamide MACMI/12 with aliphatic polyamide to achieve both robustness and flexibility. The specific composition ratio creates a material that is sufficiently hard to resist rodents and weather (Shore hardness ≥77) yet flexible enough to pass buckling tests with metal rods of various diameters.
3Object-affected harmful factors
If high Shore hardness is achieved for rodent resistance, then protective function is improved, but manufacturing complexity and formulation difficulty increase
Solution Approach 1:
The patent simplifies the formulation process by specifying concrete parameter ranges: Shore hardness of 77-95, copolyamide MACMI/12 content of 40-71%, and defined amounts of flame retardants. These parameter specifications provide clear manufacturing targets that achieve rodent protection without requiring complex formulation procedures.
Data Source
AI summary
A flame-retardant polyamide molding compound for encasing optical fibers and optical cables is proposed, comprising: (A) 40 to 71 wt.% copolyamide MACMI/12; (B) 20 to 51 wt.% at least one aliphatic polyamide; (C) 6 to 20 wt.% melamine cyanurate; (D) 3 to 10 wt.% aryl phosphate; and (E) 0 to 6 wt.% other additives; wherein components (A) to (E) supplement 100 wt.% of the polyamide molding compound. The copolyamide MACMI/12 has a laurinlactam content of 23 to 45 mol% based on the molar sum of the monomers MACM, isophthalic acid, and laurinlactam of this copolyamide, wherein the isophthalic acid in the copolyamide MACMI/12 may be wholly or partially replaced by terephthalic acid.A test specimen made from this polyamide molding compound exhibits a Shore hardness D of preferably at least 77, and a bending test is passed with a PA 12 extrudate coated with this molding compound when wound around a metal rod with a diameter of 12 mm, wherein the PA 12 extrudate for this bending test has a diameter of 1.5 mm and a coating thickness of 0.7 mm. Sheathing for optical fibers and optical cables made from this polyamide molding compound exhibits a rodent-resistant effect.