Automotive Horizontal Member Composition for Flame Retardancy and Moldability
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Solution Overview
Problem
Existing technologies for horizontal members in automobiles face issues such as poor moldability, high specific gravity, resin dripping during combustion, and inadequate flame retardancy, particularly when using large-sized members.
Innovation Solution
A horizontal member for automobiles comprising reinforcing fibers with a weight average fiber length of 5 mm to 100 mm, a thermoplastic resin, and a flame retardant, with specific tensile strength and workload properties, produced through cold pressing to ensure excellent moldability and reduced resin dripping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a papermaking method is used for production, then flame retardancy is improved, but moldability deteriorates due to large spring back
Solution Approach 1:
The invention changes the fiber length parameter to 5-100mm (optimal range 10-50mm) and controls the fiber length distribution, which fundamentally alters the material's spring back characteristics. This parameter optimization allows the material to achieve both good flame retardancy and acceptable moldability without the excessive spring back problem of conventional papermaking methods
2Reliability
If a large amount of flame retardant is added, then flame retardancy is improved, but moldability deteriorates and production cost increases
Solution Approach 1:
The invention optimizes the flame retardant content to 1-50 parts by mass per 100 parts by mass of resin (preferably 5-25 parts). This parameter optimization ensures adequate flame retardancy while preventing the material from becoming too rigid or difficult to mold, avoiding the moldability deterioration that occurs with excessive flame retardant addition
3Reliability
If a large amount of metal hydrate is used as flame retardant, then flame retardancy is improved, but specific gravity of the molded body becomes too large
Solution Approach 1:
The invention carefully controls the metal hydrate content within the overall flame retardant composition, optimizing the ratio between different flame retardant components. This parameter control achieves the required flame retardancy level while minimizing the specific gravity increase that would result from excessive metal hydrate addition
4Ease of manufacture
If fiber length is too short for injection molding, then moldability is improved, but entanglement between fibers is small and resin drip occurs during combustion
Solution Approach 1:
The invention sets the fiber length to 5-100mm (optimal 10-50mm), which is significantly longer than conventional injection molding fibers. This parameter change provides sufficient fiber entanglement to prevent resin drip during combustion while still allowing the material to be processed by injection molding, achieving both moldability and combustion resistance
5Strength
If the workload is too large, then fiber reinforcement is improved, but spring back becomes too large and moldability is extremely deteriorated
Solution Approach 1:
The invention optimizes the fiber length to 5-100mm (preferably 10-50mm) and controls the fiber length distribution, which balances the workload between fibers and matrix. This parameter optimization provides adequate tensile strength while preventing excessive spring back that would occur with longer, overly stiff fibers, thereby maintaining good moldability
Data Source
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AI summary
The present invention provides a horizontal member for automobiles, which can be easily formed and has a small resin drip after a combustion test. A horizontal member for automobiles, including: a reinforcing fiber having a weight average fiber length of 5 mm or more and 100 mm or less, a resin, and a flame retardant, in which the horizontal member for automobiles contains the flame retardant in an amount of 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the resin, and the following (a) and (b) are satisfied: (a) a tensile strength retention ratio represented by the formula (1) is 0.04% or more, Tensile strength retention ratio (%) = (tensile strength B after combustion ÷ tensile strength A before combustion) × 100 and (b) in a tensile test of a test piece having a width of 25 mm after subjected to the combustion test, a workload per basis weight is 0.5 × 10-3 or more and 100 × 10-3 [(N·mm)/(g/m2)] or less, and the maximum load per basis weight is 1.1 × 10-3 [N/(g/m2)] or more.