CN110703464A

CN110703464A - Colour local erasing blackboard

Info

Publication number: CN110703464A
Application number: CN201911040680.9A
Authority: CN
Inventors: 张富山
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-10-30
Filing date: 2019-10-30
Publication date: 2020-01-17

Abstract

The color local blackboard eraser. The sheet is composed of a vertical stack of cyan, magenta and yellow thermochromic systems containing a mixture of a leuco dye, a developer and a light-to-heat converter in a polymer matrix. The sheet is simply manufactured by a roll-to-roll (R2R) process. Writing and erasing is performed by scanning the near-infrared laser. It achieves full color photo quality images with a wide color gamut, 70% covering the Web offset publication (SWOP) standard specification and high resolution 426 ppi. Clear rewritability was also confirmed. Non-contact laser writing has other advantages because it can produce images under protective films and has flexibility in form factor. And the lifetime of the image is estimated to be over 8 years under ambient conditions. The technique will create applications for on-demand rewritable image designs while saving power consumption and reducing paper usage.

Description

Colour local erasing blackboard

Technical Field

The invention relates to the field of erasable paper, in particular to a color local erasing board.

Background

Non-volatile reflective displays have the advantage that they consume less power and reduce paper usage, which is important to sustainable society. Various non-volatile reflective displays have been developed so far, such as electrophoretic displays, 1 cholesteric LCD, 2 electrochromic displays, 3 and electroosmotic displays 4. They are driven by circuitry and are therefore useful for applications requiring frequent image updates. However, their

The color gamut has not yet reached the quality of the photographic image. For non-volatile displays where frequent image updates are not required. For example, black and white thermal rewritable recording techniques using leuco dyes have been developed to reduce the use of paper. This is advantageous because it does not require circuitry on each sheet, primarily for rewriting simple characters or bar codes on labels or cards. Full-color erasable paper has not been realized. In this context we propose a laser-addressable full-color rewritable paper with photographic image quality.

Cyan (C)/magenta (M)/yellow (Y) -a color shifting layer having a mixture of a leuco dye, a developer, a light-to-heat converter (PCA) and a polymer matrix. The PCA in each C/M/Y layer absorbs Near Infrared (NIR) light having a different wavelength. Irradiation of the NIR laser with corresponding different wavelengths enables independent rendering of the C/M/Y image and full colour photographic image quality. Our design of reversible thermochromic systems enables erasing of images by irradiating NIR laser light with optimal power density. The non-contact stretching and wiping allows the addition of hard coatings, uv and oxygen protective layers, ensuring a scratch-free surface and high volatility in 8 years under ambient conditions. Our board can be made by a roll-to-roll (R2R) process. Laser addressing has the further advantage of a high degree of freedom in design and form factor as required. It can create applications with on-demand rewritable image designs on various product surfaces.

Disclosure of Invention

The technical problem mainly solved by the invention is to provide a color local blackboard eraser, which is simply manufactured by an R2R process. Writing and erasing is performed by scanning the NIR laser. It achieves a photo quality image with a high resolution of 426 ppi and a wide color gamut covering 70% of the SWOP standard. We have also demonstrated that non-contact laser addressing has other advantages in its high form factor flexibility and that it promotes scratch resistance. The rewritability has also been confirmed for the whole range of gradations.

In order to solve the technical problem, the invention relates to the field of erasable paper, in particular to a color local erasing plate, which comprises each group of leuco dyes, color developing agents and PCA with corresponding colors which are dispersed in a solution of a polymer matrix. Then, the mixture and the solution of the heat insulating material were applied with a gravure roll and then dried with an air-float dryer to obtain a stack of the thermochromic layer and the heat insulating layer. The oxygen barrier layer, UV barrier layer and hard coat protective layer were then laminated onto a stack of thermochromic and thermal barrier layers by an R2R laminator. The total thickness of the film was 150. mu.m. The roll of sheet material is then cut to size and laminated to a substrate. Herein, we use white polyethylene terephthalate (PET) film as reference, which has a brightness L = 95. For integration into the product, an additional protective film or glass may be assembled on top of the foil. If necessary. Finally, laser writing is applied from the top.

The color local blackboard eraser has the beneficial effects that:

the invention relates to a colorful local blackboard eraser, which is simply manufactured by an R2R process. Writing and erasing is performed by scanning the NIR laser. It achieves a photo quality image with a high resolution of 426 ppi and a wide color gamut covering 70% of the SWOP standard. We have also demonstrated that non-contact laser addressing has other advantages in its high form factor flexibility and that it promotes scratch resistance. The rewritability has also been confirmed for the whole range of gradations.

Detailed Description

The specific implementation mode is as follows:

leuco dyes are known to exhibit two chemical states: a bleached and colored state. The transition between these two states can be controlled by a redox reaction between the leuco dye and the acidic compound or electron accepting compound (so-called developer). In our system, the leuco dye and developer are dispersed in a polymer matrix. The system exhibits a bistable bleached and colored state. Their transition can be controlled by the application of heat, which is known as the thermochromic phenomenon.

It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and that various changes, modifications, additions and substitutions which are within the spirit and scope of the present invention and which may be made by those skilled in the art are also within the scope of the present invention.

Claims

1. A color local blackboard eraser comprises each group of leuco dyes, color developing agents and PCA with corresponding colors are dispersed in a solution of a polymer matrix; then, coating the mixture and a solution of a heat insulating material by using a gravure roller, and then drying by using an air flotation dryer to obtain a stack of thermochromic layers and a heat insulating layer; then, laminating the oxygen barrier layer, the UV-shielding layer and the hard coat protective layer on a stack of the thermochromic layer and the thermal insulation layer by an R2R laminator; the total thickness of the film was 150 μm; the roll of sheet material is then cut to size and laminated to a substrate; white polyethylene terephthalate (PET) film was used as reference, with a brightness L × = 95; for integration into the product, an additional protective film or glass may be assembled on top of the foil.