Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1991-12-19
1993-10-12
Ryan, Patrick J.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428372, 428374, 428400, 264 78, 264181, 264182, 264208, D02G 300
Patent
active
052523969
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a shaped material such as fiber, film or the like, which changes its color reversibly depending upon its moist or dry condition, as well as to a process for producing said shaped material.
BACKGROUND ART
There are many reports on researches made with a view to increasing the sensitivity of a shaped material, for example, a fiber, and various techniques are disclosed. It is well known that the development of, in particular, a chromatic fiber capable of changing its color depending upon the external environment is in an advanced stage. A typical example thereof is a fiber which responds to temperature, light, etc.
Used therein is a technique of combining a fiber with a material inherently having a chromatic function (e.g. a thermochromic acrylic fiber obtained from a polymer mixed with a thermochromic granular material, disclosed in Japanese Patent Application Kokai Laid-Open) No. 62-184114), and there are very few examples of a technique of imparting a color-changing function to a fiber per se.
As the example of, in particular, a technique of endowing a fiber with a function of changing its color depending upon its moist or dry condition, there can be mentioned at best a method of mixing a fiber with cobalt ion. This method has problems in that the color-changing function is markedly reduced owing to the falling-off of the material having said function and further the speed of color change response is low.
DISCLOSURE OF THE INVENTION
The present inventors made research in order to develop a shaped material which per se has substantially permanently a function of changing its color depending upon its moist or dry condition and which has a high speed of response. As a result, the present inventors has completed the present invention.
The present invention relates to a shaped material consisting of a layer having open microvoids (hereinafter referred to as light-scattering layer) and a layer having a hue different from that of the light-scattering layer (hereinafter referred to as color-developing layer), the light-scattering layer constituting at least part of the outer surface of the shaped material and the color-developing layer constituting the rest of the shaped material, which shaped material changes its color reversibly depending upon its moist or dry condition.
The open microvoids refer to a microvoid structure generated by ordinary wet coagulation and mean contiguous voids of 10.ANG.-10,000.ANG. in average pore diameter communicating with each other.
As the materials constituting the light-scattering layer and the color-developing layer, an acrylonitrile polymer is used ordinarily.
In the present invention, the light-scattering layer constitutes part or the whole of the outer periphery of a fiber or a film. That is, in the cross-section perpendicular to the lengthwise direction of the fiber or the cross-section of the film, the light-scattering layer constitutes part or the whole of the circumference of the cross-section.
In the shaped material having this structure, a light incoming from outside is scattered by the light-scattering layer when the material is dry, and consequently the hue of the light-scattering layer is perceived; however, the hue of the portion of the color-developing layer covered by the light-scattering layer cannot be perceived. When the shaped material is moist, however, the microvoids of the light-scattering layer are filled with water and consequently the light-scattering layer loses the light-scattering ability. In this case, since the incoming light can reach as far as the color-developing layer via the light-scattering layer, both of the hue of the light-scattering layer and the hue of the color-developing layer are perceived even if the color-developing layer is covered by the light-scattering layer. As a result, the shaped material has a hue completely different from the hue perceived when dry. When the shaped material changes from a moist condition to a dry condition, a completely opposite color change takes place.
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Patent Abstracts of Japan, vol. 13, No. 593 (M-914), Dec. 27, 1989, & JP-A-12-50-554, Oct. 5, 1989, Takagi Mitsuaki, "Decorative Material For Interior Part".
Fukui Yuichi
Hagura Shigeki
Itoh Hajime
Muraoka Itsumi
Edwards N.
Mitsubishi Rayon Co. Ltd.
Ryan Patrick J.
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