Red optical color-changing sheet and preparation method thereof

Abstract

The invention discloses a red optical color-changing sheet. The thin sheet is provided with a central reflecting layer; and a basic structure including a first dielectric layer, a first metal light splitting layer and a second dielectric layer is symmetrically or asymmetrically arranged in sequence from the central reflection layer to the outside. Proper material and film thickness are selected, the symmetrical or asymmetric structure is used to form a film system structure with a long red waveband, supersaturated red in a CIE1931 system is constructed, the main peak of the red waveband is moved forwards to a high visual efficiency region on the premise that the phase length of a red interval is met, the half-wave width of a red region is reduced, the color purity and the color changing performance are guaranteed, a red chromaticity region in the CIE1931 system is displayed in a front-view color manner, the visual effect is optimized, and the purposes of reducing the film thickness, improving the material utilization rate and reducing the energy consumption are achieved.

Description

Technical field: [0001] The invention relates to the technical field of optical anti-counterfeiting and the technical field of high-grade color printing and coating, in particular to a red optical color-changing sheet and a preparation method thereof. Background technique: [0002] The optically variable pigment (OVP) based on the principle of thin-film multi-beam interference is a high-end anti-counterfeiting material in the field of anti-counterfeiting. The color displayed by it has the characteristic of changing with the viewing angle. Scanning cannot be reproduced, the anti-counterfeiting performance is extremely strong, and it can be recognized by human eyes, so it has been widely used in currency, securities, tobacco, alcohol and high-end coating markets, especially in daily commodities. It is required that such optically variable materials not only have optically variable anti-counterfeiting functions, but also have better color display effects. Especially red or bur...

AI Technical Summary

Problems solved by technology

[0006] Through the analysis of its film structure, there are several problems: 1. The film thickness is too thick, and the total film thickness of each cycle is about 1 μm; 2. The position of the main peak is at 700nm or beyond, and the half-wave width is very wide. From the perspective of visual color , the color of the wave band after 680nm is black, and it is invisible to non-experts. It is in the low-efficiency zone of human eyesight, resulting in insufficient brightness; For the Red area

Correspondingly, some adverse effects are caused: 1. The internal stress of the film is large, the film layer is unstable during the production process, and the film is easy to burst; 2. The diameter-thickness ratio is small under the same particle size, and the film layer is not flat during printing. The color display effect is greatly reduced; 3. Printing the same area requires more pigments, which is a waste of materials; 4. The wave peak is located in the low-efficiency area of ​​human vision, and the color is dark and the effect is poor. 5. The range of color display area is Red Pure red, no wine red (Purplish Red or Reddish purple)

[0007] During the film growth process, as the film layer grows, its stress continues to accumulate, and the thicker film thickness causes the stress of the entire film system to be too large. Due to the release layer in the film system, this layer acts as a vulnerable layer. The role of separation is relatively weak, and it is easy to cause film cracks due to stress during the production process, which affects the number of cycles per furnace and thus affects production capacity

At the same time, it means that the coating time of each cycle is relatively long, resulting in waste of raw materials and energy consumption, and the unit construction cost increases in printing.

[0008] Because in the manufacturing process, the commonly used method in this field is to use the combination of resistance evaporation and electron gun evaporation in the box coating machine, intermittent production, and the production capacity is relatively low

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