Energy-consumption-free liquid crystal colored recyclable writing tool and preparation method thereof

Abstract

The invention discloses an energy-consumption-free liquid crystal color recyclable writing tool and a preparation method thereof, and belongs to the field of liquid crystal materials and display. The recyclable writing tool comprises a writing board and a writing pen; the writing board is made of a cholesteric liquid crystal polymer film; the writing pen is dipped with pen ink with different hydrogen ion concentrations; the cholesteric liquid crystal polymer film has the characteristic of reflecting circularly polarized light with single rotation, and the concentration change of hydrogen ions can cause expansion or compression of a polymer grid, so that the screw pitch of the cholesteric liquid crystal is changed, the reflection band of the cholesteric liquid crystal is adjusted, and the color of the cholesteric liquid crystal polymer film is changed. After the writing pen writes on the writing board, the cholesteric liquid crystal polymer film of the writing board absorbs moisture and volatilizes, the film returns to be colorless again, and meanwhile, the film is cleaned again by using an alkaline solution to return to a colorless state, so that recycling is realized; the method has the advantages of high response speed, rich color, recyclability, low cost and the like.

Description

Technical Field

[0001] This invention belongs to the field of liquid crystal materials and displays, specifically relating to a recyclable writing instrument with zero energy consumption liquid crystal color and its preparation method. Background Technology

[0002] With the development of science and technology, the disadvantages of traditional writing methods have become increasingly prominent. For example, ink writing increases the environmental burden on paper usage, and its pungent odor can harm human health. The dust generated by chalk writing is also a major pain point for educators. Therefore, LCD writing tablets have gradually emerged in recent years, mainly because they offer advantages that traditional writing methods cannot match. For instance, LCD writing tablets allow users to write and erase repeatedly, avoiding frequent paper replacements, thus saving a significant amount of paper and promoting environmental protection. This paper-free writing method greatly reduces the space occupied by paper and notebooks for students and office workers, making them easier to carry. At the same time, LCD writing tablets offer more diverse functions, supporting the saving and transfer of written content to other devices, providing more digital functions, and facilitating information management and sharing. Compared to traditional digital screens such as mobile phones and computers, LCD writing tablets offer a better writing experience, closer to paper writing. The biggest advantages are their low power consumption and safety. LCD writing tablets can typically last for a long time, avoiding the high power consumption and damage problems of traditional screens. They also do not emit blue light like traditional electronic devices, reducing eye fatigue and making them suitable for prolonged use.

[0003] Most LCD writing tablets on the market currently use voltage to change the arrangement of liquid crystal molecules to display colored writing marks, or other low-energy mechanical responses. These tablets suffer from slow response times, limited color options, or the inability to change colors once set, resulting in a poor writing experience. Energy consumption is also a problem for current LCD writing tablets. They either use rechargeable batteries, which increase portability and cost, or button batteries, but button batteries have a significant impact on human health and the environment. Considering the potential for accidental ingestion by children, they pose a significant safety hazard. Furthermore, the environmental pollution caused by their internal chemical components cannot be underestimated. Therefore, developing an energy-efficient, color-rich, and recyclable LCD writing tablet is a key technological challenge for further improving the practicality of LCD displays. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a cholesteric liquid crystal polymer film responsive to hydrogen ions and a method for preparing an energy-free, reusable, color liquid crystal writing board. This cholesteric liquid crystal polymer film is prepared by using a liquid crystal mixture composed of liquid crystal monomers, non-polymerizable liquid crystals, hydrogen-bonding molecular triggers, chiral agents, photoinitiators, and crosslinking agents to form a pristine cholesteric liquid crystal polymer network film. After treatment with acetone or tetrahydrofuran solution and alkali, a polymer network film is formed. Based on the characteristic of cholesteric liquid crystals reflecting circularly polarized light with a single rotation, changes in hydrogen ion concentration cause expansion or compression of the polymer network, thereby altering the pitch of the cholesteric liquid crystal and adjusting its reflective band, thus changing the color of the polymer film. Different hydrogen ion concentrations result in different film colors, achieving color writing. At the upper concentration boundary, the film displays red; at the lower concentration boundary, the film displays blue. When the hydrogen ion concentration reaches the upper boundary, due to the reflective effect of the cholesteric liquid crystal, red light is reflected to the human eye, resulting in red writing. When the hydrogen ion concentration reaches the lower limit, blue light is reflected to the human eye due to the reflection effect of the cholesteric liquid crystal, making the writing blue. After the writing ink evaporates, the film becomes colorless, enabling cyclic writing.

[0005] This patent is designed based on the optical properties of cholesteric liquid crystals. While avoiding the problems of traditional writing materials, it also features simple manufacturing, low cost, fast response, rich colors, and zero energy consumption, making it safer and better able to meet users' writing needs.

[0006] This invention provides a recyclable writing tool with zero energy consumption and liquid crystal color printing. The recyclable writing tool includes a writing board and a writing pen. The writing board is made of a cholesteric liquid crystal polymer film. The writing pen is dipped in ink with different hydrogen ion concentrations, and writes on the writing board to produce different colored handwriting. The cholesteric liquid crystal polymer film has the characteristic of reflecting circularly polarized light with a single rotation. Because the change in hydrogen ion concentration causes the expansion or compression of the polymer mesh, it changes the pitch of the cholesteric liquid crystal, thereby adjusting the reflection band of the cholesteric liquid crystal, and the color of the cholesteric liquid crystal polymer film changes.

[0007] Furthermore, at room temperature, the hydrogen ion concentration in the ink is greater than 10. -7 The ink is displayed in red; the hydrogen ion concentration in the ink is less than 10. -7 The writing is displayed in blue.

[0008] Furthermore, after the writing pen writes on the writing board, the cholesteric liquid crystal polymer film of the writing board absorbs moisture and evaporates, and the film will return to colorless, thus achieving recycling; at the same time, it is cleaned again with a 0.1 mol / L alkaline solution to return it to a colorless state, thus achieving recycling.

[0009] This invention provides a method for preparing a recyclable writing instrument with zero-energy liquid crystal color, wherein the cholesteric phase liquid crystal polymer film is specifically:

[0010] Step 1: Spin-coat PVA solution onto the pretreated glass substrate, dry it, and then perform rubbing alignment to obtain a functionalized glass substrate.

[0011] Step 2: Dissolve the liquid crystal monomer, non-polymerizable liquid crystal, hydrogen bond molecule trigger, chiral agent, photoinitiator, and crosslinking agent in a solvent, ultrasonically vibrate and mix them evenly, then heat to obtain a uniformly mixed liquid crystal polymer solution;

[0012] Step 3: Place the functionalized glass substrate on the worktable, use a capillary tube to draw the liquid crystal polymer solution to the edge of the functionalized glass substrate, use a scraper to scrape and coat it, and cure it under ultraviolet light after alignment to obtain a cholesteric liquid crystal polymer network film.

[0013] Step 4: The cholesteric liquid crystal polymer film is first soaked in a solvent to remove the non-polymerizable liquid crystal and then dried, followed by alkali treatment and drying to obtain a cholesteric liquid crystal polymer film that is sensitive to pH value.

[0014] Further, in step 1, the pretreatment of the glass substrate is as follows: nitrogen gas is used to blow away surface dust and impurities, and after immersion in anhydrous ethanol, ultrasonic cleaning is performed; the concentration of the PVA solution is 8-10 wt%; the drying temperature of the PVA solution is 70℃-80℃, and the time is 10-15 min; the PVA solution is evenly applied to the dried glass substrate, and then placed in a spin coater and rotated at 500 r / min for 2 min.

[0015] 6. The method for preparing the energy-saving liquid crystal color recyclable writing instrument according to claim 4, characterized in that, in step 2, the liquid crystal monomer is RM23; the crosslinking agent is RM257; the non-polymerizable liquid crystal is 5CB; the hydrogen bond molecular triggering agent is two of 6OBA, POBA and 4OBA; the chiral agent is LC756; and the photoinitiator is Ig369.

[0016] Further, in step 2, the solvent is an acrylic acid solution; the mass ratio of the liquid crystal monomer, hydrogen bond molecular trigger, crosslinking agent, non-polymerizable liquid crystal, photoinitiator, and chiral agent is 30:43.8:13:8.2:0.5:4.5; the heating temperature is 110-130℃, and the time is 3-5 min.

[0017] Furthermore, in step 3, the operating table temperature is 40°C, and the time is 25–30 minutes.

[0018] Furthermore, in step 3, the curing process involves irradiating the surface with a 365nm UV lamp for 5–10 minutes.

[0019] Furthermore, in step 4, the solvent for removing the non-polymerizable liquid crystal is acetone or tetrahydrofuran, and the soaking time is 10 min; the alkali treatment uses a 1-1.2 mol / L KOH solution.

[0020] The beneficial effects of this invention are as follows:

[0021] The hydrogen ion concentration-responsive liquid crystal polymer film writing tool provided by this invention differs from existing traditional writing methods or other responses. This invention is based on the hydrogen ion concentration response of a cholesteric phase liquid crystal polymer network. By changing the hydrogen ion concentration of the ink, the polymer network expands and contracts, and its response reflection band essentially covers the visible light range. This allows for writing in multiple colors, rapid erasure of ink marks, and reusability. The writing tool of this invention has advantages such as fast response speed, rich colors, reusability, and low cost. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating the preparation process of the cholesteric phase liquid crystal polymer film of the present invention.

[0023] The reference numerals in the figure are: (a) original cholesteric liquid crystal mixing, (b) glass substrate coating orientation, (c) UV curing, (d) organic solvent and KOH alkali treatment, and (e) cholesteric liquid crystal polymer film.

[0024] Figure 2 This is a schematic diagram of the writing tool of the present invention for cyclic writing;

[0025] The attached diagram is labeled as follows: 1. Colorless writing board; 2 and 3. Brush and corresponding color strokes for hydrogen ion concentration ①; 4 and 5. Brush and corresponding color strokes for hydrogen ion concentration ②; 6 and 7. Hydrogen ion concentration ③ and corresponding color strokes; 8. Colorless writing board after ink evaporation; 9 and 10. Circular writing. Note: The colors of the characters in 3, 5, and 7 are different. Detailed Implementation

[0026] The present invention will now be further described with reference to the accompanying drawings.

[0027] This invention aims to provide a zero-energy, color, and reusable liquid crystal thin film writing board tool. It proposes a feasible solution to achieve different colors of writing by utilizing the different concentrations of hydrogen ions in the cholesteric liquid crystal network, which leads to different reflective bands. It features zero energy consumption, rich colors, fast response, and low cost.

[0028] The color, energy-free, recyclable writing board based on cholesteric liquid crystal networks of this invention is prepared by the following method:

[0029] 1. Use nitrogen to blow away surface dust and impurities from the glass substrate, immerse it in anhydrous ethanol, and then place it in an ultrasonic cleaner for rinsing. After removing and drying, apply 8-10 wt% PVA solution evenly to the substrate, place it in a spin coater and rotate it at 500 rpm for 2 minutes. After removing and drying, perform rubbing alignment.

[0030] 2. Select specific liquid crystal monomers, photoinitiators, non-polymerizable chiral dopants with adjustable proportions, non-polymerizable liquid crystals, crosslinking agents, hydrogen bond molecular triggers, etc., and mix these materials in a certain proportion; the mass ratio is 30:0.5:4.5:8.2:13:43.8.

[0031] 3. Heat the mixed material to 110-130℃ to achieve isotropy, pick up the liquid crystal on the 40℃ operating table and apply it to the edge of the glass plate, use a scraper to scrape it, wait for it to be oriented to form a cholesteric liquid crystal film, and then cure it with ultraviolet light.

[0032] 4. Remove the cured liquid crystal film and immerse it in an organic solvent to remove the non-polymerizable liquid crystal 5CB. After removing it and fully evaporating the organic solvent, place it in an alkaline solution for alkaline treatment, and then remove and dry it. The preparation of the cholesteric polymer film with hydrogen ion concentration response is then complete.

[0033] 5. Expand and fix the film to create a writing board of suitable size, and adjust the ink with different hydrogen ion concentrations to achieve writing in different colors. Create an alkaline cleaning brush; if the effectiveness decreases after multiple uses, alkaline treatment will restore its original effectiveness.

[0034] Example 1

[0035] 1. Blow away surface dust and impurities from the glass substrate with nitrogen gas, immerse it in anhydrous ethanol for 5 minutes, then place it in an ultrasonic cleaner for 3 minutes. After drying, apply PVA solution evenly to the substrate, place it in a spin coater and rotate it at 500 rpm for 2 minutes. After drying, perform rubbing alignment.

[0036] 2. Selected liquid crystal monomers RM23, 5CB, photoinitiator Ig369, chiral agent LC756, crosslinking agent RM257, hydrogen bond triggering agents POBA and 4OBA, etc., are mixed in a mass ratio of 30:8.2:0.5:4.5:13:21.9:21.9 and ultrasonically vibrated to ensure uniform mixing. The mixture is then placed in an electric heating drying oven and heated to 130℃. After maintaining the temperature for 10 minutes, it is removed.

[0037] 3. Fix the treated glass substrate on a 40°C operating table, drip the liquid crystal mixture onto the edge of the liquid crystal glass plate, and use a scraper to scrape it. After alignment is completed, irradiate it under a UV lamp for 8 minutes to cure.

[0038] 4. Peel off the cured liquid crystal film with a scalpel, soak it in tetrahydrofuran solvent for 3 minutes to wash away the non-polymerizable liquid crystal 5CB, and then put it into an electric heating drying oven at 20-30℃ to evaporate excess organic solvent.

[0039] 5. The liquid crystal film was immersed in a 1 mol / L KOH solution for 2 minutes to form a carboxylate that responds to hydrogen ions. The film was then removed and dried. The alkali treatment breaks hydrogen bonds to form a carboxylate, which responds to solutions of different pH values; the preparation of the colorless, erasable cholesteric phase liquid crystal polymer film is now complete.

[0040] 6. A colorless hydrogen-bonded cholesteric liquid crystal film is expanded and fixed to form a writing board. By adjusting the ink with different hydrogen ion concentrations, different colors of writing can be obtained. After the ink evaporates, the writing disappears and returns to colorless, achieving recycling.

[0041] In summary, various elemental liquid crystals RM23, 4OBA, POBA, RM257, 5CB, photoinitiators, and chiral agents are mixed and cured in a certain proportion, and then treated with tetrahydrofuran solution to create a polymer network responsive to hydrogen ion concentration. Polymerizable cholesteric liquid crystals fill this network. Since the light reflection band of the cholesteric liquid crystal largely depends on the molecular pitch, changes in the hydrogen ion concentration of the ink cause the polymer network to expand or compress, thus altering the pitch of the cholesteric liquid crystal, which macroscopically manifests as a color change in the film. Based on this color change, the hydrogen ion concentration of the ink can be rationally designed. By adjusting the concentration of the chiral agent, the wavelength range of the reflection band at the upper and lower boundaries of the hydrogen ion concentration value is roughly consistent with the visible light wavelength range. When the set hydrogen ion concentration of the ink is absorbed, due to the effect of the cholesteric liquid crystal reflection band, light of a specific color is reflected to the human eye. Changing the hydrogen ion concentration of the ink produces different colored handwriting. Once the ink evaporates, the written content disappears, allowing for the recycling of the writing tablet.

[0042] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A recyclable, energy-efficient liquid crystal color writing instrument, characterized in that, The recyclable writing tool includes a writing board and a writing pen; the writing board is made of a cholesteric liquid crystal polymer film; the writing pen is dipped in ink with different hydrogen ion concentrations, and writes on the writing board to produce different colored strokes; the cholesteric liquid crystal polymer film has the characteristic of reflecting circularly polarized light with a single rotation, and because the change in hydrogen ion concentration will cause the polymer mesh to expand or compress, thereby changing the pitch of the cholesteric liquid crystal, thus adjusting the reflection band of the cholesteric liquid crystal, and the color of the cholesteric liquid crystal polymer film changes.

2. The energy-saving liquid crystal color recyclable writing instrument according to claim 1, characterized in that, At room temperature, the hydrogen ion concentration in the ink is greater than 10. -7 The ink is displayed in red; the hydrogen ion concentration in the ink is less than 10. -7 The writing is displayed in blue.

3. The energy-saving liquid crystal color recyclable writing instrument according to claim 1, characterized in that, After the writing pen writes on the writing board, the cholesteric liquid crystal polymer film of the writing board absorbs moisture and evaporates, and the film will return to colorless, thus achieving recycling. At the same time, it can be cleaned again with a 0.1 mol / L alkaline solution to return it to a colorless state, thus achieving recycling.

4. A method for preparing a recyclable writing instrument with zero energy consumption liquid crystal color as described in claim 1, characterized in that, The cholesteric phase liquid crystal polymer film is specifically: Step 1: Spin-coat PVA solution onto the pretreated glass substrate, dry it, and then perform rubbing alignment to obtain a functionalized glass substrate. Step 2: Dissolve the liquid crystal monomer, non-polymerizable liquid crystal, hydrogen bond molecule trigger, chiral agent, photoinitiator, and crosslinking agent in a solvent, ultrasonically vibrate and mix them evenly, then heat to obtain a uniformly mixed liquid crystal polymer solution; Step 3: Place the functionalized glass substrate on the worktable, use a capillary tube to draw the liquid crystal polymer solution to the edge of the functionalized glass substrate, use a scraper to scrape and coat it, and cure it under ultraviolet light after alignment to obtain a cholesteric liquid crystal polymer network film. Step 4: The cholesteric liquid crystal polymer film is first soaked in a solvent to remove the non-polymerizable liquid crystal and then dried, followed by alkali treatment and drying to obtain a cholesteric liquid crystal polymer film that is sensitive to pH value.

5. The method for preparing the energy-saving liquid crystal color recyclable writing instrument according to claim 4, characterized in that, In step 1, the pretreatment of the glass substrate is as follows: nitrogen gas is used to blow away surface dust and impurities, and after immersion in anhydrous ethanol, ultrasonic cleaning is performed; the concentration of the PVA solution is 8-10 wt%; the drying temperature of the PVA solution is 70℃-80℃, and the time is 10-15 min; the PVA solution is evenly applied to the dried glass substrate and placed in a spin coater and rotated at 500 r / min for 2 min.

6. The method for preparing the energy-saving liquid crystal color recyclable writing instrument according to claim 4, characterized in that, In step 2, the liquid crystal monomer is RM23; the crosslinking agent is RM257; the non-polymerizable liquid crystal is 5CB; the hydrogen bond initiator is two of 6OBA, POBA and 4OBA; the chiral agent is LC756; and the photoinitiator is Ig369.

7. The method for preparing the energy-saving liquid crystal color recyclable writing instrument according to claim 4, characterized in that, In step 2, the solvent is an acrylic acid solution; the mass ratio of the liquid crystal monomer, hydrogen bond molecule trigger, crosslinking agent, non-polymerizable liquid crystal, photoinitiator, and chiral agent is 30:43.8:13:8.2:0.5:4.5; the heating temperature is 110-130℃, and the time is 3-5 min.

8. The method for preparing the energy-saving liquid crystal color recyclable writing instrument according to claim 4, characterized in that, In step 3, the operating table temperature is 40℃ and the time is 25-30 minutes.

9. The method for preparing the energy-saving liquid crystal color recyclable writing instrument according to claim 4, characterized in that, In step 3, the curing process involves irradiating the surface with a 365nm UV lamp for 5–10 minutes.

10. The method for preparing the energy-saving liquid crystal color recyclable writing instrument according to claim 4, characterized in that, In step 4, the solvent for removing the non-polymerizable liquid crystal is acetone or tetrahydrofuran, and the soaking time is 10 min; the alkali treatment uses a 1-1.2 mol / L KOH solution.

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