Core-Sheath Composite Fiber Using Calcium Carbonate for White Opacity
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Solution Overview
Problem
Existing nonwoven fabrics used in sanitary applications face challenges with titanium oxide as a white pigment due to safety concerns, sustainability issues, and difficulties in reducing plastic volume by high-concentration incorporation, while maintaining opacity and processability.
Innovation Solution
A core-sheath conjugate fiber is developed using calcium carbonate in the core and/or sheath components, with specific resin compositions and drawing processes to enhance white opacity and sustainability, avoiding titanium oxide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If titanium oxide is incorporated into resins to improve opacity, then the white appearance and opacity of nonwoven fabrics are enhanced, but safety concerns arise due to its classification as a carcinogen
Solution Approach 1:
The patent extracts and removes titanium oxide from the resin composition entirely, replacing it with calcium carbonate as the white pigment. This extraction eliminates the carcinogenic hazard while maintaining the desired opacity function through alternative inorganic particles with appropriate refractive indices.
Solution Approach 2:
The patent employs calcium carbonate, a naturally abundant, non-toxic, and inexpensive inorganic material, as a substitute for titanium oxide. This replacement provides a safe, sustainable, and cost-effective solution that maintains optical properties without the health risks associated with titanium oxide.
2Stability of the object's composition
If titanium oxide is used as a white pigment, then excellent stability and high refractive index are achieved, but sustainability issues arise as it is an underground mineral resource
Solution Approach 1:
The patent changes the material parameter from a non-renewable mineral resource (titanium oxide) to a renewable, naturally abundant material (calcium carbonate). This substitution maintains the functional properties of high refractive index and stability while improving sustainability by using a material that is more environmentally friendly and potentially recyclable.
3Ease of operation
If inorganic particles with low refractive index are incorporated into resins, then softness is improved, but white appearance and opacity cannot be achieved
Solution Approach 1:
The patent applies local quality by selectively incorporating calcium carbonate particles with appropriate size distribution and concentration into the resin matrix. This localized optimization ensures that the inorganic particles provide both the desired softness through proper dispersion and the necessary white appearance through sufficient refractive index contrast, achieving multiple functions simultaneously.
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 fiber achieves enhanced safety, sustainability, and opacity comparable to titanium oxide-based fibers, reducing resin usage and plastic volume, with improved mechanical properties and process stability.
Implementation Method 1
it has been thought difficult to achieve white appearance and opacity comparable to those imparted by titanium oxide, simply by incorporating these inorganic particles or talc into a resin
Implementation Method 2
a sheath component containing a polyolefin resin having a melting point that is lower than a melting point of the polyester resin by 20°C or more
Implementation Method 3
the core component has a maximum peak temperature of crystal melting of lower than 255°C, as measured with a differential scanning calorimeter
Data Source
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AI summary
It is an object of the present invention to provide a core-sheath conjugate fiber that exhibits excellent white opacity without using titanium oxide. The core-sheath conjugate fiber of the present invention includes a core component containing a polyester resin; and a sheath component containing a polyolefin resin having a melting point that is lower than a melting point of the polyester resin by 20°C or more, wherein either or both of the core component and the sheath component contain calcium carbonate in an amount of more than 1.0% by mass and 30.0% by mass or less based on 100% by mass of each component, the core component has a maximum peak temperature of crystal melting of lower than 255°C, as measured with a differential scanning calorimeter, and the fiber has an L* value of 91 or more and a b* value of 5.0 or less, which indicate a hue of the fiber.