Composite Artificial Hair with Polyamide Core and Polyester Sheath
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Solution Overview
Problem
Artificial hair used in wigs often lacks the natural feel and behavior of human hair, particularly in terms of moisture absorbency, tensile strength, elasticity, and bending rigidity, leading to issues like bundling and unnatural appearance under different humidity conditions.
Innovation Solution
The development of artificial hair with a cross-sectional size of 50 to 100 µm and a double structure of polyethylene terephthalate and polybutylene terephthalate, combined with a sheath/core structure of polyamide resins, which adjusts bending rigidity and moisture absorbency to match natural hair, and the formation of fine pores on the surface to reduce gloss and enhance tactile similarity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyester fibers are used for artificial hair, then strength and heat stability are improved, but moisture absorbency becomes extremely low and bending rigidity becomes too high, resulting in unnatural feel and bundling under high humidity
Solution Approach 1:
The patent uses a composite structure with a polyamide resin core (providing moisture absorbency and flexibility) and a polyester resin sheath (providing strength and heat stability). This composite approach allows the artificial hair to simultaneously achieve the strength of polyester fibers while maintaining the moisture absorbency and bending flexibility of polyamide fibers, preventing bundling and achieving natural behavior under high humidity conditions.
2Reliability
If polyamide fibers are used for artificial hair, then appearance and physical properties similar to natural hair are achieved, but bending rigidity becomes too low, resulting in poor standing up when attached to wig base
Solution Approach 1:
The patent employs a composite structure where the polyamide resin core maintains moisture absorbency and natural appearance characteristics, while the polyester resin sheath provides enhanced bending rigidity and strength. This allows the artificial hair to stand up properly when attached to a wig base while retaining the appearance and moisture behavior similar to natural hair.
3Shape
If artificial hair has high bending rigidity, then standing up is improved, but tactile feeling becomes rough and adaptability to wearer's own hair is poor
Solution Approach 1:
The composite structure with polyamide core and polyester sheath creates a balanced bending rigidity that allows the artificial hair to stand up properly while maintaining smooth tactile feeling. The polyamide core provides flexibility and softness similar to natural hair, while the polyester sheath provides sufficient rigidity for proper positioning, achieving both good standing up and comfortable tactile sensation.
4Stability of the object's composition
If polyester fibers are used, then shape preservation is improved, but the artificial hair does not show natural behavior that physical properties change with humidity
Solution Approach 1:
The composite structure combines polyester resin (providing shape preservation and heat stability) with polyamide resin (providing moisture absorbency and humidity responsiveness). The polyamide core absorbs moisture from the environment, causing the artificial hair to expand and soften in high humidity conditions similar to natural hair, while the polyester sheath maintains overall shape integrity and prevents excessive deformation.
Data Source
Figure 1~2
Figure 3
Figure 4(A)~4(B)
AI summary
An artificial hair bundle (10) is made up by mixing a first artificial hair made of a polyester resin (1, 2) and a second artificial hair made of a polyamide resin (5, 6), and the first artificial hair (1, 2) is made of polyethylene terephthalate and polybutylene terephthalate, having a cross-sectional size and bending rigidity similar to those of natural hair, wherein the bending rigidity is in the range of about 6.5 to 7.8 X 10-3gf· cm2/strand at humidity 40 %, and the first artificial hair (1, 2) suppresses bundling of the second artificial hair (5, 6), and the first and the second artificial hairs (1, 2, 5, 6) behave similarly to natural hair.