CN113568213A - A kind of manufacturing method of polymer honeycomb liquid crystal blackboard - Google Patents

Abstract

Translated fromChinese

本发明提供一种聚合物蜂网液晶黑板的制造方法。该黑板的聚合物含量介于15～30％之间，由两片透明导电胶片夹层聚合物蜂网胆甾相液晶膜构成，其中下层导电胶片外背面涂有黑漆；其聚合物是沿光束传播方向为易聚合方向的柔性单体与柔性低聚物聚合而成的聚合物；其胆甾相液晶是由向列相液晶添加手性剂配制成的短螺距胆甾相液晶。该液晶黑板的制造方法是采用特殊的经过准直较弱紫外光强垂面曝光进行相分离，聚合物形成沿复合胶片制品表面法线方向分布的较大的蜂巢孔道网络，即形成聚合物蜂网液晶黑板。该聚合物蜂网液晶黑板在零电场时为黑态；施加按压应力后着力部位呈现着色态，黑态与着色态具有比较明显的反差对比构成书写显示效果。

The invention provides a manufacturing method of a polymer honeycomb liquid crystal blackboard. The blackboard has a polymer content between 15% and 30%, and is composed of two transparent conductive films sandwiched by a polymer honeycomb cholesteric liquid crystal film, wherein the outer and back sides of the lower conductive film are coated with black paint; The cholesteric liquid crystal is a short-pitch cholesteric liquid crystal prepared by adding a chiral agent to the nematic liquid crystal. The manufacturing method of the liquid crystal blackboard is to use special collimated weak ultraviolet light intensity vertical exposure to carry out phase separation, and the polymer forms a larger honeycomb channel network distributed along the normal direction of the surface of the composite film product, that is, the polymer honeycomb is formed. Mesh LCD blackboard. The polymer honeycomb liquid crystal blackboard is in a black state when the electric field is zero; after applying a pressing stress, the stress part is in a colored state, and the black state and the colored state have a relatively obvious contrast to form a writing display effect.

Description

Manufacturing method of polymer honeycomb mesh liquid crystal blackboard

Technical Field

The invention relates to a method for manufacturing a liquid crystal dust-free large blackboard for a classroom, in particular to a method for manufacturing a polymer bee net cholesterol phase liquid crystal blackboard.

Background

As a composite system of a polymer and a liquid crystal (polymer/liquid crystal composite system), it is known to divide into a Polymer Dispersed Liquid Crystal (PDLC) and a Polymer Network Liquid Crystal (PNLC). The polymer dispersed liquid crystal has polymer content over 30%, and the polymer forms matrix with microsphere cavity filled with dispersed liquid crystal in small droplets. Polymer network liquid crystals are polymers with a polymer content of less than about 15%, the liquid crystals forming a matrix and the polymers forming a network of silk-chain strands discretely distributed in the liquid crystal layer. The PDLC product which is industrialized and has a large market is applied to an electric control light adjusting film; the PNLC product which is industrialized and has a large market is applied to a liquid crystal blackboard (polymer network stabilized cholesteric liquid crystal). The small-sized liquid crystal blackboard is also commonly called a liquid crystal writing board, and the large-sized liquid crystal blackboard is a liquid crystal dust-free blackboard suitable for classrooms. The large-area polymer dispersed cholesteric liquid crystal dust-free blackboard has huge market prospect, is concerned by people and becomes an investment hotspot. Li fenghua proposed a classroom liquid crystal blackboard system, a blackboard eraser, a flexible hand-written liquid crystal screen and a manufacturing method thereof (CN106527007B), and the structural principle, the manufacturing method and the application of the classroom liquid crystal blackboard have been described in detail. Because the liquid crystal dust-free blackboard is used under the condition of vertical suspension, the writing is thick and bright, the liquid crystal ratio in the polymer network liquid crystal is very high, the polymer ratio is very small, and the polymer network mainly has the function of providing bistable property of cholesteric liquid crystal plane state and focal conic state, namely Polymer Stabilized Cholesteric Liquid Crystal (PSCLC), and the polymer network can not play a role in enhancing the adhesive strength of the composite film. In the liquid crystal blackboard product manufactured by the conventional process, liquid crystal microdroplets cannot be completely bound by the polymer network, the polymer network cannot firmly adhere the film, and liquid crystals are easy to settle and accumulate at the bottom of the blackboard after the liquid crystal blackboard product is vertically used for a long time. Therefore, the liquid crystal above the blackboard is less, the liquid crystal below the blackboard is more, the lower part of the blackboard expands, the liquid crystal layer becomes thick, and the product fails. In order to solve the problem of failure of the liquid crystal blackboard product after long-term use, the prior possible technical scheme is to adopt a secondary exposure technology to manufacture a polymer wall so as to solve the problem of failure caused by liquid crystal flowing (CN1851549A, CN1749836A and the like), and the defects are that the process becomes complicated and the cost is increased. The invention provides a novel special manufacturing process for manufacturing a liquid crystal dust-free blackboard, which aims to solve the problem of service life of the liquid crystal blackboard.

Disclosure of Invention

As mentioned above, the present invention provides a method for manufacturing a polymer mesh liquid crystal dust-free blackboard of a new composite system of polymer and liquid crystal, wherein the polymer content of PDLC is above 30%, and the polymer content of PNLC is below 15%.

The special process method provided by the invention is that the content of the polymer is 15-30%, the weak ultraviolet light intensity is adopted for carrying out the collimation vertical surface long-time exposure, and the pre-polymer component is composed of flexible monomers and oligomers which are mainly taken along the light beam propagation direction as the easy polymerization direction. The product manufactured by the special process method tends to firmly bond the upper film and the lower film and restrict the cholesteric liquid crystal to be in a focal conic state because the polymer network yarn chain has higher density, thicker and softer. When a pressing stress is applied, the polymer is softer, so that cholesteric liquid crystal can be converted into a plane state from a focal conic state, and the effect of the liquid crystal handwriting board can be realized.

The invention is realized by adopting the following technical scheme:

a liquid crystal dustless blackboard is a large-area liquid crystal writing board which is formed by two conductive films and a layer of polymer dispersed cholesteric liquid crystal.

The invention provides a special process method for manufacturing a large-area liquid crystal dust-free blackboard, which comprises the following steps:

firstly, preparing a polymer bee net cholesterol-phase liquid crystal prepolymer mixed solution (for example, the ratio of the prepolymer to the cholesteric phase liquid crystal is 0.25 to 0.75, and mixing a proper amount of spacers such as 5 mu m powder) by adopting a conventional process;

secondly, respectively uncoiling the upper conductive film and the lower conductive film, and coating the mixed solution between the conductive films by adopting a conventional process (the upper one of the two conductive films is a transparent conductive film, and the lower one is an opaque conductive film coated with black paint);

thirdly, laminating on special laminating machine equipment by adopting a conventional process to form a uniform thin-layer composite film by the prepolymer and the liquid crystal mixed liquid layer;

fourthly, two compounded films which are clamped with the prepolymer bee net cholestan phase liquid crystal are continuously and slowly moved and flatly paved on an overlong platform under the drive of a laminating roller, the alignment vertical plane weak light intensity exposure is carried out by adopting a special process, the exposure time is tens of minutes, and the composite film is completely cured;

and finally, cutting according to the specification and the size of the product, and handing over to a post-process manufacturing workshop.

The basic principle of the present invention is as follows.

As PDLC and PNLC are known in the industry, a new name is required to be given to a new composite system of polymer and liquid crystal with the polymer content of 15-30%. It is conceivable that such a content of polymer is such that it does not form a polymer matrix in which the liquid crystal is dispersed, nor does it form a discretely interlaced network, but rather forms a sufficiently dense network, or even interconnected cell microcavities. As an ideal model, it is not supposed that a honeycomb network, referred to as a honeycomb network for short, is formed, and then this new composite system of polymer and liquid crystal can be further referred to as "polymer honeycomb network liquid crystal (PHLC)" or "polymer honeycomb network cholesteric liquid crystal (PHCLC)". The invention provides a special process method of a polymer honeycomb net liner steroid phase liquid crystal dust-free blackboard, aiming at solving the problem of service life of the liquid crystal dust-free blackboard, enabling the product to have the advantages of liquid crystal sedimentation and accumulation resistance and manufacturing the durable liquid crystal dust-free blackboard. The invention not only fills up the blank in the research field of polymer and liquid crystal composite systems, but also improves the manufacturing method of the liquid crystal dustless large blackboard for classrooms.

The existing liquid crystal blackboard is structured by polymer network liquid crystal, and in order to achieve the purpose of firm bonding of an upper film and a lower film, secondary exposure such as the technology of manufacturing polymer micro-walls and the like may be needed. The polymer network liquid crystal concept means that the polymer network silk chain density is higher, the vertical plane polymerization components are more, the bonding strength of PDLC can be achieved, and the flexible polymer network has the writing function of PNLC. The vertical polymerization components are firmly adhered, so that the liquid crystal cannot flow freely, the problem of liquid crystal sedimentation and accumulation in the liquid crystal dust-free blackboard can be solved, and the service life of the liquid crystal dust-free blackboard is obviously prolonged.

In the existing PDLC or PNLC products, people naturally adopt a surface light source to carry out ultraviolet light exposure phase separation, which is a known technology in the industry. The manufacturing method of the trans-polymer honeycomb mesh liquid crystal blackboard emphasizes ultraviolet light exposure according to a special process, and is characterized in that a light source is collimated vertical plane incident ultraviolet light. This is based on the recent research efforts of the present inventors, and it was experimentally found that some linear monomers and oligomers have a characteristic of being easily polymerizable in the direction of propagation of a light beam. Optically, if the direction of beam propagation is taken as the z-axis and the direction of perpendicular beam propagation is taken as the x-and y-axes, some monomers tend to polymerize along the z-direction of beam propagation, while some other monomers tend to polymerize along the x-and y-directions of perpendicular beam propagation. From the view point of molecular physics, pi electron cloud or sigma electron cloud exists in organic matter molecules, and can be stably or concussively influenced or not influenced by polarized light disturbance, so that polymerization or non-polymerization occurs, and then photo-induced directional polymerization reaction occurs. The invention provides a manufacturing method of a polymer bee cholesteric phase net liquid crystal blackboard, which is characterized in that a polarized light induced oriented polymerization monomer is adopted, and a light source is a collimated light source for vertical incident ultraviolet light exposure, so the invention has innovation on materials and process technical conditions of the manufacturing method.

The material requirements of the present invention are linear monomers or oligomers that can be photo-induced to polymerize directionally along the direction of propagation of the light beam, and such monomers or oligomers are readily found experimentally. Compared with the prior art, the PDLC or PNLC product adopts a large-area ultraviolet light source in the manufacturing process, and the invention needs to adopt a collimation vertical plane incident point light source, so that a collimation diaphragm device needs to be added between the surface light source and the product to meet the requirement of transforming the surface light source into the collimation vertical plane incident point light source.

Compared with the prior art, the invention has the beneficial effects that:

the polymer and liquid crystal composite system proposed in the past is PDLC with relatively high polymer content or PNLC with relatively low polymer content, and no special attention is paid to the system with the polymer content of approximately 15-30%, so that the polymer and liquid crystal composite system has innovation in the concept of polymer mesh liquid crystal (PHLC).

In the existing liquid crystal dust-free blackboard manufacturing technology, although a polymer network cholesteric liquid crystal layer is formed after exposure, the polymer content is too low to completely separate the liquid crystal in a dispersing way, and a liquid crystal communicating body is formed. When the liquid crystal handwriting board is used as a small-area liquid crystal handwriting board product, the polymer content is slightly higher, the handwriting can be thinner, the liquid crystal droplets can be smaller, and the liquid crystal handwriting board is usually in a flat-laid state, so that the sedimentation and accumulation of liquid crystals are avoided. However, when the liquid crystal dust-free blackboard is used as a large-area liquid crystal dust-free blackboard, the polymer content is lower in a vertical suspension state, writing is thicker, liquid crystal droplets are larger, and liquid crystals can be deposited downwards due to the liquid crystal connectors. Over time, the upper liquid crystal flows away and cannot write, the lower liquid crystal swells, the liquid crystal becomes more membrane layer and becomes thicker, and the upper liquid crystal cannot be written and erased. In the special process, compared with more polymer honeycomb net silk chains, the two conductive films are bonded more firmly, and the polymer honeycomb net cholesta phase liquid crystal can effectively solve the problem of liquid crystal sedimentation and accumulation.

Drawings

FIG. 1 is a schematic diagram of the principle of a prestressed front focal conic PHCLC blackboard: 1. gluing a film substrate; 2. an ITO conductive layer is arranged; 3. the easy vertical plane is polymerized into a polymer bee net with a main vertical orientation; 4. the focal conic state spiral is easy to distribute oriented cholesteric liquid crystal molecules along the surface; 5. a lower ITO conductive layer; 6. a lower film substrate; 7. and coating black paint on the back.

FIG. 2 is a schematic diagram of the display principle of planar PHCLC after stress: 8. gluing a film substrate; 9. an ITO conductive layer is arranged; 10. the easy vertical plane is polymerized into a polymer bee net with a main vertical orientation; 11. cholesteric liquid crystal molecules with planar helices oriented in the vertical direction; 12. a lower ITO conductive layer; 13. a lower film substrate; 14. and coating black paint on the back.

FIG. 3 is a schematic diagram of a device for transforming a surface light source into a collimated vertical incident point light source: 15. an ultraviolet light area light source; 16. a collimating diaphragm array; 17. an article of manufacture.

Detailed Description

The present invention is described below with reference to specific examples.

Step one, preparing a cholesteric liquid crystal and prepolymer mixed solution according to a conventional process: X3P-1189 (n) from Nicotiana Kogyo for cholesteric liquid Crystal_o＝1.519，n_e1.769, delta n is 0.250) and chiral agent S5011; the prepolymer monomer which is easy to polymerize along the light beam propagation direction is made of eaglewood chemical products EM211 ethoxyethoxyethyl acrylate (EOEOEA) and EM 2132-hydroxypropyl acrylate (beta-CEA), the eaglewood chemical product EM70 isoborneol acrylate (IBOA) is used as a flexible dilution monomer, the flexible oligomer is made of a product 270 of Mitsuoki corporation with high viscosity and an EM6101 with low viscosity, and the high-viscosity product CN9893 is used as a high-adhesion oligomer, wherein the mixing ratio of the prepolymer mixed liquid of the monomer and the oligomer is (EOEA): (beta-CEA): (IBOA): (6101): (270): (9893) -0.07: 0.03: 0.3: 0.2: 0.1; a small amount of photoinitiator 1173 (2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP) was added to the prepolymer at a ratio of 0.25: 0.75 (1: 3) of prepolymer mixture to cholesteric liquid crystal.

Secondly, uncoiling according to a conventional process, pouring mixed liquid into two films, and laminating the films, wherein the upper film is a transparent conductive film, and the lower film is an opaque conductive film with the back coated with black paint; the viscosity of the mixed liquid of the cholesteric liquid crystal and the prepolymer is lower, and the mixed liquid can be easily poured into a film according to the conventional process.

And thirdly, ultraviolet light exposure (light intensity of 0.1kW/m2 and exposure time of 20min) is carried out according to a special process, and the device is characterized in that a light source is collimated vertical plane incident ultraviolet light (a schematic diagram of the device is shown in figure 3), an exposure platform is long, and the film moving speed is slow.

The polymer honeycomb mesh liquid crystal blackboard prepared by the steps is a black composite film in appearance, and after a pressing stress is applied, the cholesteric liquid crystal spiral vertical plane is oriented to become a color handwriting capable of displaying character patterns, so that the writing function of the liquid crystal blackboard is realized, and the erasing function is realized by applying an electric field.

In summary, the above-described examples illustrate the invention in detail, but do not limit the scope of the invention. After reading this disclosure, those skilled in the art will make minor changes and modifications to the invention without departing from the spirit and scope of the invention.

Claims (3)

1. A polymer honeycomb liquid crystal blackboard is characterized by comprising:

the composite film consists of two conductive film interlayer polymer bee net liquid crystal layers;

the polymer is formed by polymerizing a photopolymerisable flexible monomer and a flexible oligomer along the propagation direction of the light beam, wherein the direction of the photopolymerisable flexible monomer is the easy polymerization direction;

the liquid crystal is a short-pitch cholesteric liquid crystal prepared by adding a chiral agent into a nematic liquid crystal;

the polymer content is between 15 and 30 percent.

2. A manufacturing method of a polymer honeycomb mesh liquid crystal blackboard is characterized by comprising the following steps:

step one, preparing a cholesteric liquid crystal, a prepolymer and a mixed solution mixed with a small amount of spacers according to a conventional process;

secondly, laminating the two films with the mixed solution on a laminating machine according to a conventional process;

and thirdly, performing ultraviolet exposure on the composite film on an exposure machine according to a special process, wherein the special process is characterized in that an ultraviolet light source with weaker intensity is adopted, and a collimating diaphragm array which enables ultraviolet light beams to enter in a vertical plane is additionally arranged between the light source and a product.

3. A polymer bee net liquid crystal blackboard is characterized in that the polymer bee net liquid crystal blackboard is in a black state in a zero electric field; after the pressing stress is applied, the stressed part is in a colored state, and the black state and the colored state have obvious contrast to form a writing display effect.

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