Rayon Fiber Pellets Preventing Production Cracking
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Solution Overview
Problem
Pellets produced by impregnating reinforcing fiber bundles with thermoplastic resin are prone to cracking during production.
Innovation Solution
Using rayon fibers with specific properties and a thermoplastic resin with a melt flow rate (MFR) of 70 to 200 g/10 min, and adjusting the pellet length to between 3 to 30 mm to reduce cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If glass fibers are used as reinforcing fibers to increase mechanical strength, then the mechanical strength of molded articles is improved, but the pellets are prone to cracking during production
Solution Approach 1:
The patent changes the material parameter from glass fibers to rayon fibers, which have different physical and chemical properties. Rayon fibers have better flexibility and lower brittleness compared to glass fibers, which prevents cracking during pellet production while maintaining reinforcement effectiveness. This material substitution resolves the contradiction between strength enhancement and crack resistance.
Solution Approach 2:
The patent creates a composite system using rayon fibers combined with specific thermoplastic resins (polypropylene or polyacetal). The composite structure leverages the high strength-to-weight ratio of rayon fibers while the thermoplastic matrix provides ductility and crack resistance, achieving both mechanical strength improvement and production reliability.
2Stability of the object's composition
If a thermoplastic resin with low MFR is used to maintain structural integrity, then the resin maintains its shape well, but the impregnation of fiber bundles becomes difficult
Solution Approach 1:
The patent optimizes the MFR parameter of the thermoplastic resin to a specific range (70-200 g/10min at 230°C). This parameter adjustment balances the resin's viscosity characteristics, providing sufficient flowability for complete fiber bundle impregnation while maintaining adequate shape stability during molding. The specific MFR range resolves the contradiction between impregnation ease and shape stability.
3Productivity
If the pellet length is increased to reduce the number of pellets needed, then the productivity is improved, but the pellets become more prone to cracking
Solution Approach 1:
The patent optimizes the pellet length parameter to a specific range (3-30 mm number average length). This parameter optimization achieves the best balance between productivity and crack resistance. Pellets within this length range are long enough to reduce the total number of pellets needed (improving productivity) but short enough to maintain structural integrity and resist cracking during handling and injection molding.
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 effectively prevents cracking of pellets during production, enabling the formation of strong molded articles from these pellets.
Implementation Method 1
bringing the fiber bundle and the molten resin into contact with each other in the die to impregnate the fiber bundle with the molten resin
Implementation Method 2
cooling and cutting the fiber bundle
Implementation Method 3
cooling and cutting the fiber bundle
Data Source
AI summary
To provide pellets, a molded article formed from the pellets, and a method for producing pellets. The Pellets contain: a thermoplastic resin; and a bundle of 2000 to 30000 rayon fibers arranged in parallel in the fiber length direction, wherein at least a portion of the thermoplastic resin is impregnated into the bundle of 2000 to 30000 rayon fibers, the thermoplastic resin has a melt flow rate (MFR) of 70 to 200 g/10 min when measured at a temperature of 230° C. and a load of 2.16 kg according to JIS K 7210, rayon fibers of the bundle have a number average fiber diameter of 5 to 30 μm, and a number average length of the pellets is from 3 to 30 mm.