JPH046899Y2 - - Google Patents

Description

[Detailed explanation of the idea]

The present invention relates to a color-forming laminated film. Specifically, it relates to the structure of a laminated film in which colors are developed by the interference of irradiated light without adding pigments such as dyes or pigments. The purpose is to develop any color without adding pigments such as dyes or pigments, depending on the type and direction of the irradiating light source, as well as the type, thickness, number of transparent films, and lamination direction of the transparent film used as the material. The object of the present invention is to provide a color-developing laminated film that has extremely high utility value. Conventionally, there has been no film that is simply a stack of transparent films that do not contain dyes, and that allows the film layers to develop a clear color simply by irradiating the film with transmitted light. In nature, examples of colors that develop without pigments include the iridescent color of peacock feathers that interfere with light due to melamine particles arranged in a lattice pattern, and the ladders on the surface of the wings of the Brazilian solar butterfly. It is known that the spacing of the scales and the refractive index interfere with light, resulting in color that changes subtly depending on the viewing angle. As a result of various studies to obtain a means for producing color using only a transparent film without dyes, the present inventor discovered that when light rays pass through a polymer film or are reflected between films, the light rays can be directed in a specific direction and at a specific wavelength. It can be obtained by combining multiple polarizing films and one or more refractive index anisotropic polymer films, using the principle that if they overlap with a phase difference, interference will occur and a coloring phenomenon will occur. They discovered that a laminated film can produce extremely clear coloring phenomena, and arrived at the present invention. That is, two or more polarizing films are arranged in parallel so that their polarization directions are perpendicular or parallel to each other, and one or more refractive index anisotropic polymer films are placed between the polarizing films with respect to the polarizing films. By interposing the anisotropy in an oblique direction, the inventors have devised a color-forming laminated film which is characterized by being colored by irradiation with transmitted light. The present invention will be explained with reference to the drawings. FIG. 1 is an enlarged vertical cross-sectional view of one embodiment of the laminated film of the present invention. As shown in this figure, in the present invention, for example, two polarizing films 1 and 2 are arranged in parallel at an appropriate interval, and between the polarizing films 1 and 2 at least one refractive index anisotropic polymer film 3, 3'... is interposed. In this case, the polarizing film 1 on the upper side of the figure and the polarizing film 2 on the lower side of the figure are arranged in parallel so that their polarization directions are perpendicular or parallel, while the refractive index anisotropic polymer films 3, 3' ...is polarizing film 1,
The anisotropy is in the diagonal direction with respect to No. 2. This refractive index anisotropic polymer film is a film in which the orientation of its polymer chains is anisotropic, that is, the molecular orientation differs depending on the vertical and horizontal directions.
The result is a film whose refractive index has directionality (details will be described later), such as a free width uniaxially stretched film, a constant width uniaxially stretched film, an anisotropic biaxially stretched film, and a stretched tape. The refractive index anisotropic polymer film 3 is arranged so that its anisotropy is oblique to the polarizing films 1 and 2, that is, for example, the stretching direction of the uniaxially stretched film is relative to the polarization direction of the polarizing films 1 and 2. They are stacked diagonally rather than perpendicularly or parallelly. In other words, the largest laminated film of the present invention can be obtained by laminating them in the 45 degree direction where the refractive index anisotropy is maximum and sandwiching them between the polarizing films 1 and 2. Figure 2 is a diagram for explaining the coloring phenomenon in the laminated film of the present invention, where shows the case where two polarizing films are arranged in parallel, and shows the case where two polarizing films are arranged orthogonally. , A represents the front view, and B represents the front view. In the case of this figure 2, two polarizing films 1,
2 is used, and only one refractive index anisotropic polymer film 3 is interposed therebetween. When two polarizing films 1 and 2 are installed so that their polarization directions are parallel to each other as shown in the figure, when light ray a passes through polarizing film 1, it is called polarized light b, which has vibration waves in only one direction. When the light passes through the next refractive index anisotropic polymer film 3, it is arbitrarily refracted depending on the long axis direction of the refractive index anisotropy and its degree, interferes, and then passes through the next polarizing film 2. Therefore, only light of a specific wavelength, for example, red wavelength, is allowed to pass through and the color is developed. On the other hand, when the polarization directions of the polarizing film 1 and the polarizing film 2 are orthogonal to each other as shown in the figure, the polarized light b is refracted by the refractive index anisotropic polymer film 3 and becomes interference light, and the polarized light is film 2
In this case, only light with a wavelength that is complementary to the wavelength that passed in the case of the parallel position is passed through, for example, if the parallel position is red, only green wavelength is passed through, and the color is developed in that color. . In the present invention, if either the polarizing film 1 or 2 is laminated in a rotatable manner, each time the polarizing film 1 or 2 is rotated by 90 degrees, a color and its complementary color will be alternately developed, so that the color can be freely changed. It becomes a film. In other words, the laminated film has both the functions shown in FIG. 2, and by arbitrarily rotating the polarizing film 1 or 2, it is possible to change the color development. Note that the arrow c in the figure indicates that there is a complementary color relationship. The laminated film of the present invention exhibits a phenomenon in which its color changes to iridescent light by moving the transmitted light. Therefore, even if the transmitted light is in a fixed direction, a similar phenomenon occurs when the viewer's viewing angle moves, and iridescent light is observed. Examples of this transmitted light include daylight, white light, fluorescence, sodium light, and laser light.
By changing the irradiation angle from perpendicular to almost parallel to the laminated film surface, and by irradiating various light beams or transmitted light of various wavelengths singly or in combination, a wide variety of hues can be seen by the viewer. Moreover, this hue change also changes depending on the viewing angle of the viewer, so the color change is very beautiful. Furthermore, it is not only due to changes in transmitted light or viewing angle, but also due to the type, thickness, number, degree of molecular orientation, refractive index, etc. of the refractive index anisotropic polymer film 3 sandwiched between the polarizing films 1 and 2. Any hue can be selected, and by bending or wrinkling the polymer film 3, or interposing it in a random overlapping state, it is possible to create a variety of hues such as iridescent or rainbow-like. It is. Materials for the refractive index anisotropic polymer film used in this invention include polyethylene, polypropylene,
All polymer films such as polystyrene, polyvinyl chloride, polyvinyl alcohol, ethylene vinyl acetate copolymer, nylon, and polyester are applicable. However, the colors produced by the above-mentioned mechanism differ depending on the thickness of each film and the degree of refractive index anisotropy. In other words, this color is optically determined by a value called retardation (compensation). This retardation is the value obtained by multiplying the birefringence (Δn) by the thickness, and the in-plane birefringence (Δn ₁₂ ) of the film is the refraction index (n ₁ ) on the vertical axis (stretching direction) and the refraction on the horizontal axis. The difference from the rate (n ₂ ), that is, Δn ₁₂ = n ₁ − n ₂ . In other words, the presence of refractive index anisotropy within the film plane means that the value of Δn ₁₂ is not zero. Tables 1 and 2 show the relationship between the refractive index anisotropy and the color development of the laminated film of the present invention using a stretched polystyrene film having a thickness of 200 μm.

【table】

【table】

[Table] However, one refractive index anisotropic polymer film was used, and two polarizing films manufactured by 3M Company in the United States were used. As can be seen from the table above, the laminated film of the present invention can be colored in any desired color. The range of applications of the laminated film of the present invention is extremely wide, such as store displays, stage costumes, curtains, variable color signal lights (red to green), and the laminated film of the present invention is cut into long strips and shaped into tapes or fibers. If used by twisting and twisting as necessary, it can be used to create various woven and knitted fabrics with iridescent colors, and can also be used in the same way as laminates and mixed yarns. As explained in detail above, the present invention is a color-forming laminated film that is extremely vivid and changes beautifully without using any dyes.
It brings about revolutionary effects in its color change and iridescent to rainbow-like color expressions.
Its application range is wide and it is extremely useful.

[Brief explanation of the drawing]

FIG. 1 is an enlarged vertical cross-sectional view of one embodiment of the laminated film of the present invention. Figure 2 is a diagram for explaining the coloring phenomenon in the laminated film of the present invention, where shows the case where two polarizing films are arranged in parallel, and shows the case where two polarizing films are arranged at right angles. , A is a front view, and B is a front view. 1, 2...Polarizing film, 3,3'...Refractive index anisotropic polymer film, a...Light ray, b...Polarized light.

Claims (1)

[Claims for Utility Model Registration] 1. Two or more polarizing films arranged in parallel so that their polarization directions are perpendicular or parallel to each other, and one or more refractive index anisotropic polymer films are placed between the polarizing films. By interposing the polarizing film so that its anisotropy is in an oblique direction,
A color-forming laminated film characterized in that it develops color upon irradiation with transmitted light. 2. The color-forming laminated film according to claim 1, which is made by laminating one sheet of polarizing film in a rotatable manner so that a color and its complementary color appear each time the film is rotated by 90 degrees. .