CN101311796A - Method for manufacturing reflective optical film, reflective polarizing film and method for manufacturing the same - Google Patents

Abstract

The invention discloses a manufacturing method of a reflective optical film, a reflective polarizing film and a manufacturing method thereof. The manufacturing method of the reflective optical film comprises the following steps: providing a substrate, forming a compensation film on at least one side of the substrate by coating, and forming a cholesterol liquid crystal layer on the compensation film by coating. Therefore, the difficulty of the traditional external-pasting process can be reduced, and the problems of poor optical result and incapability of displaying compensation effect caused by more disordered arrangement of the upper layer of the cholesterol liquid crystal compared with the lower layer can be solved.

Description

Manufacturing method of reflective optical film, reflective polarizing film and manufacturing method thereof

technical field

The present invention relates to an optical film structure and a manufacturing method thereof, and in particular to a reflective optical film manufacturing method, a reflective polarizer film and a manufacturing method thereof.

Background technique

A liquid crystal display usually utilizes linearly polarized light generated by two polarizing films to achieve a display effect, and its main light source is provided by a backlight module. When the light generated by the backlight module passes through the first polarizing plate, it produces linearly polarized light; as the liquid crystal molecules in the display are arranged and twisted, it reaches the second polarizing plate and changes in brightness and darkness.

However, because the light must go through many layers of material refraction, reflection and absorption, the light emitted from the LCD will become less than 5% of the light intensity. In particular, the absorption and light transmission of the polarizer in the display has become one of the main factors affecting the brightness. Therefore, strengthening the intensity of the light source and increasing the light transmittance is currently one of the key points for improving the display.

At present, there are two methods for increasing the overall light transmittance of the display: increasing the penetration effect of incident light and increasing the light source of the backlight module. Among them, the main method of the first effect is to increase the transmittance of the polarizing film, or change the polarization state of the incident light before the incident light enters the polarizing film, so that the polarization state of the incident light is parallel to the polarization of the polarizing film, increasing the incident light penetration efficiency.

The so-called changing the polarization state of the incident light is a way to make the incident light parallel to the polarization of the polarizing film to achieve high penetration light intensity. At present, the reflective polarizer (DBEF, Dual Brightness Enhancement Film) made by 3M Company and the cholesteric liquid crystal ( Cholesteric Liquid Crystal, CLC) reflective polarizing film and other brightness-enhancing films.

The optical element of the cholesteric liquid crystal reflective polarizer, its main principle is to use the separation characteristics of left-handed and right-handed circularly polarized light of cholesteric liquid crystal to separate the incident unpolarized white light into right-handed circularly polarized light, in which the circular polarized light with opposite optical rotation Polarized light can be transmitted, while circularly polarized light with the same optical rotation is reflected, and then re-reflected into circularly polarized light that can pass through, increasing the light passing rate. With 1/4 wavelength retardation film (also known as "λ/4 film"), the circularly polarized light passing through will be converted into linearly polarized light and then enter the polarizing film. The final result is that the light source has been completely converted into a polarized state that can pass through the polarizer completely achieve a brightening effect.

However, currently, lamination of polarizers, cholesteric liquid crystals, and λ/4 films requires rotating layers or 45-degree lamination, which are very complicated and time-consuming processes. In addition, the reflective optical film composed of cholesteric liquid crystal and λ/4 film often has poor optical results and cannot display the λ/4 effect, which needs to be solved urgently.

Contents of the invention

The invention provides a method for manufacturing a reflective optical film to reduce the difficulty of the traditional external sticking process and overcome the problem of poor optical results and failure to display the λ/4 effect because the upper layer of the cholesteric liquid crystal is more chaotic than the lower layer. question.

The invention provides a reflective polarizing film, which can greatly reduce the film thickness of the polarizing film.

The invention provides a method for manufacturing a reflective polarizing film to reduce the technical difficulty of combining the polarizing film, cholesteric liquid crystal and compensation film at present.

The invention proposes a method for manufacturing a reflective optical film, which includes firstly providing a substrate, then forming a layer of compensation film on at least one side of the substrate by coating, and then forming a layer of compensation film on the compensation film by coating Cholesteric liquid crystal layer.

In the first embodiment of the present invention, the above coating method is selected from spin coating method (SpinCoating), slot die coating method (Slot-die Coating), extrusion die coating method (ExtrusionCoating), One of the methods of wire-wound rod coating (Mayer Rod Coating) and blade coating. Moreover, the coating method can also be a continuous roll to roll (Roll to Roll) process.

In the first embodiment of the present invention, the aforementioned substrate is a transparent substrate or an opaque substrate.

In the first embodiment of the present invention, the aforementioned compensation film is a λ/4 film.

In the first embodiment of the present invention, the compensation film and the cholesteric liquid crystal layer can be fabricated inside or outside the display unit (cell).

The present invention further proposes a reflective polarizing film, which includes a substrate, a rotating layer, a polarizing film, a compensation film and a cholesteric liquid crystal layer, wherein the rotating layer is composed of an ultra-thin cholesteric liquid crystal with a thickness less than 1 μm. The compensation film and the polarizing film are respectively located above and below the rotating layer. The cholesteric liquid crystal layer is on the compensation film. As for the substrate, it can be located between the compensation film and the rotating layer or under the polarizing film.

In the second embodiment of the present invention, the aforementioned substrate is a transparent substrate or an opaque substrate.

In the second embodiment of the present invention, the above-mentioned substrate includes a panel glass.

In the second embodiment of the present invention, the above-mentioned substrate further includes a thin film transistor.

In the second embodiment of the present invention, the above-mentioned substrate further includes a color filter.

In the second embodiment of the present invention, the above substrate further includes an alignment layer.

In the second embodiment of the present invention, the aforementioned compensation film is a λ/4 film.

The present invention also proposes a manufacturing method of the above-mentioned reflective polarizing film, which is to form a rotating layer, a polarizing film, a compensation film and a cholesteric liquid crystal layer on the substrate by coating, and the above-mentioned compensation film is formed before the above-mentioned cholesteric liquid crystal layer .

In the third embodiment of the present invention, the above-mentioned coating method is selected from spin coating method, slot die coating method, extrusion die coating method, wire wound rod coating method and knife coating method. at least one method. Also, the coating method may be a roll-to-roll continuous process.

In the third embodiment of the present invention, the above-mentioned rotating layer and polarizing film can be fabricated inside or outside the display unit (cell).

In the third embodiment of the present invention, the compensation film and the cholesteric liquid crystal layer can be fabricated inside or outside the display unit.

In the third embodiment of the present invention, the above-mentioned substrate is a transparent substrate or an opaque substrate.

In the third embodiment of the present invention, the aforementioned compensation film is a λ/4 film.

Because the present invention uses different liquid crystal materials for alignment and coating, cholesteric liquid crystal and compensation coating, and 45-degree rotating polarizing film optical axis coating process, it can improve the optical effect caused by the chaotic arrangement of the upper layer of the cholesteric liquid crystal than the lower layer. At the same time, it overcomes the problem that the compensating phase difference film that is originally aligned in the forward direction is arranged in a radial arrangement because the arrangement of the upper layer of the cholesteric liquid crystal is more chaotic than that of the lower layer, and the compensation effect cannot be displayed. In addition, the present invention utilizes ultra-thin (<1 μm) cholesteric liquid crystals that are not reflective in the visible region as the spin layer, and cooperates with the step of forming a compensation film first and then forming a cholesteric liquid crystal layer to carry out the full coating process, so it can be greatly improved. Reduce the process difficulty of reflective polarizing film and reduce its thickness.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, preferred embodiments will be described in detail below together with the accompanying drawings.

Description of drawings

FIG. 1 is a process diagram of a reflective optical film according to the first embodiment of the present invention.

2A and 2B are respectively cross-sectional views of two kinds of reflective polarizing films according to the second embodiment of the present invention.

3A and 3B are process steps diagrams of two kinds of reflective polarizing films according to the third embodiment of the present invention, respectively.

[Description of main component symbols]

100～104, 300～308, 400～408: steps

200: Substrate

202: Polarizing film

204: Rotation layer

206: Compensation film

208: Cholesteric liquid crystal layer

Detailed ways

The invention is fully described hereinafter accompanied by the accompanying drawings, in which embodiments of the invention are shown. However, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity.

Spatially relative terms such as "below," "on," "between," and similar terms are used herein for convenience of description, to Describe the relationship of one layer or feature as illustrated in the figures to another layer or feature(s). It will be understood that the above spatially relative terms are intended to encompass different orientations of the element in use or operation in addition to the orientation depicted in the figures. For example, if the elements in the figures are turned over, layers (or elements) described as being "below" or "beneath" a layer (or element) would then be oriented to be "beneath" the layer (or element) ) "above". Therefore, the so-called "below..." may include both orientations above and below.

FIG. 1 is a process diagram of a reflective optical film according to the first embodiment of the present invention.

Referring to FIG. 1 , in step 100, a substrate is provided, and the substrate is a transparent substrate or an opaque substrate. And when the first embodiment is applied to a display unit (display cell), the substrate can be a panel glass; or, at least one of thin film transistors, color filters and alignment layers has been formed on the substrate, so that The subsequently formed optical film can be directly or indirectly formed on the above various elements as required.

Then in step 102, a layer of compensation film is formed on at least one side of the substrate in a coating manner, wherein the coating method is, for example, selected from spin coating method (Spin Coating), slot die coating method (Slot- die Coating), Extrusion Coating, Mayer Rod Coating and Blade Coating. Moreover, the coating method can also be a continuous roll (Roll to Roll) process. In addition, the above-mentioned compensation film, such as a λ/4 film, is formed by coating a liquid crystal having a λ/4 phase difference on a substrate by means of coating, and then curing it by means of ultraviolet light or the like.

Afterwards, step 104 is performed to form a layer of cholesteric liquid crystal layer on the compensation film by coating, wherein the coating method is, for example, selected from spin coating method, slit die coating method, extrusion die coating method, One of the methods of wire-wound rod coating method and blade coating method, and the coating method can also be a continuous reel process. The method of forming the cholesteric liquid crystal layer is not only coating the cholesteric liquid crystal with a thickness of the reflective area on the compensation film, but also curing the cholesteric liquid crystal by means of ultraviolet light or the like. Since the thickness of the cholesteric liquid crystal layer is generally thicker than that of the compensation film, if necessary, the above steps of coating and curing the cholesteric liquid crystal can be repeated until the desired thickness of the reflection area is obtained.

The above step 102 and step 104 are irreversible, and the coating methods adopted in the two steps may be the same or different.

In addition, the compensation film and the cholesteric liquid crystal layer can be fabricated inside or outside the display unit (cell).

2A and 2B are respectively cross-sectional views of two kinds of reflective polarizing films according to the second embodiment of the present invention.

Please refer to FIG. 2A and FIG. 2B at the same time. The reflective polarizing film in the second embodiment includes a substrate 200, a polarizing film 202, a rotating layer 204, a compensation film 206 and a cholesteric liquid crystal layer 208, wherein the rotating layer 204 is determined by the thickness Ultra-thin cholesteric liquid crystals less than 1 μm are formed, and the compensation film is, for example, a λ/4 film. The compensation film 206 and the polarizing film 202 are respectively located above and below the rotating layer 204 . The cholesteric liquid crystal layer 208 is on the compensation film 206 . The substrate 200 can be located under the polarizing film 202 (as shown in FIG. 2A ); or, the substrate 200 can be located between the compensation film 206 and the rotating layer 204 (as shown in FIG. 2B ). The aforementioned substrate 200 includes a transparent substrate or an opaque substrate.

And when the reflective polarizing film of the second embodiment is applied to a display unit, the substrate 200 can be a panel glass; or, at least one of a thin film transistor, a color filter and an alignment layer has been placed on the substrate 200 (not shown).

3A and 3B are process steps diagrams of two kinds of reflective polarizing films according to the third embodiment of the present invention, and FIG. 3A is the step of FIG. 2A , and FIG. 3B is the step of FIG. 2B .

The method of the third embodiment is mainly to form various layers on the substrate by coating, and the compensation film is formed before the cholesteric liquid crystal layer. Among them, in FIG. 3A, a polarizing film is sequentially formed on the substrate (such as step 302), a rotating layer is formed on the polarizing film (such as step 304), a compensation film is formed on the rotating layer (such as step 306), and the compensation film A cholesteric liquid crystal layer is formed on it (such as step 308).

In Fig. 3B, a compensation film (as in step 402) and a spin layer (as in step 406) are respectively formed on both sides of the substrate, and a cholesteric liquid crystal layer is formed on the compensation film (as in step 404), and on the spin layer What is formed is a polarizing film (eg step 408).

Please continue to refer to FIG. 3A and FIG. 3B , the substrate in steps 300 and 400 can be a transparent substrate or an opaque substrate. The coating methods in steps 302-308 and 402-408 are, for example, selected from spin coating method, slot die coating method, extrusion die coating method, wire wound rod coating method and knife coating method. At least one of the methods, and the coating methods used in each step can be different or the same method according to actual needs. In addition, the aforementioned coating method may be a roll-to-roll continuous process.

In addition, in FIG. 3A and FIG. 3B , the rotation layer and the polarizing film can be fabricated inside or outside the display unit, and the compensation film and the cholesteric liquid crystal layer can also be fabricated inside or outside the display unit. The compensation film can be a λ/4 film.

In summary, the present invention is characterized in that:

1. The present invention uses the full coating process to manufacture the cholesteric liquid crystal layer and the compensation film, so it can reduce the difficulty of the traditional external sticking process. Moreover, the cholesteric liquid crystal layer must be carried out after coating the compensation film. If the order is different, the optical result will be poor because the upper layer of the cholesteric liquid crystal is more chaotic than the lower layer, and the compensation retardation film (such as λ /4 film) presents a radial arrangement and cannot show a compensation effect.

2. In the present invention, a rotating layer is arranged on the polarizing film to rotate the optical axis of the polarizing film and the alignment axis by 45 degrees, and the rotating layer of the present invention is composed of non-reflective ultra-thin cholesteric liquid crystals with a thickness less than 1 μm. Therefore, the cholesteric liquid crystal is not reflective in the visible light region, and the polarizing film is rotated by 45 degrees by using the rotation of the liquid crystal arrangement.

3. The rotating layer and polarizing film of the present invention can also be made by the full coating process, so the difficulty of the traditional external sticking process can be reduced.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be defined by the claims.

Claims (20)

1. A method for manufacturing a reflective optical film, comprising: Provide the substrate; forming a compensation film on at least one side of the substrate by coating; and A cholesteric liquid crystal layer is formed on the compensation film by coating. 2. The manufacture method of the reflective optical film as claimed in claim 1, wherein the coating method is selected from spin coating method, slot die coating method, extrusion die coating method, wire wound rod coating One of the method and blade coating method. 3. The method for manufacturing a reflective optical film according to claim 2, wherein the coating method comprises a roll-to-roll continuous process. 4. The method for manufacturing a reflective optical film as claimed in claim 1, wherein the substrate is a transparent substrate or an opaque substrate. 5. The method for manufacturing a reflective optical film as claimed in claim 1, wherein the compensation film comprises a λ/4 film. 6. The method for manufacturing a reflective optical film as claimed in claim 1, wherein the compensation film and the cholesteric liquid crystal layer can be fabricated inside or outside the display unit. 7. A reflective polarizing film, comprising: The spin layer is composed of ultra-thin cholesteric liquid crystals with a thickness less than 1 μm; a compensation film on the rotating layer; a polarizing film located under the rotating layer; a cholesteric liquid crystal layer on the compensation film; and The substrate is located between the compensation film and the rotating layer or under the polarizing film. 8. The reflective polarizing film as claimed in claim 7, wherein the substrate is a transparent substrate or an opaque substrate. 9. The reflective polarizing film as claimed in claim 7, wherein the substrate comprises panel glass. 10. The reflective polarizing film as claimed in claim 7, wherein the substrate further comprises a thin film transistor. 11. The reflective polarizing film as claimed in claim 7, wherein the substrate further comprises a color filter. 12. The reflective polarizing film as claimed in claim 7, wherein the substrate further comprises an alignment layer. 13. The reflective optical film of claim 7, wherein the compensation film comprises a λ/4 film. 14. A method for manufacturing a reflective polarizing film according to claim 7, characterized in that: Forming a spin layer, a polarizing film, a compensation film and a cholesteric liquid crystal layer on a substrate by coating; and The compensation film is formed earlier than the cholesteric liquid crystal layer. 15. The manufacturing method of reflective polarizing film as claimed in claim 14, wherein the coating method is selected from spin coating method, slot die coating method, extrusion die coating method, wire wound rod coating At least one of cloth method and blade coating method. 16. The method for manufacturing a reflective polarizing film as claimed in claim 15, wherein the coating method comprises a roll-to-roll continuous process. 17. The method for manufacturing a reflective polarizing film as claimed in claim 14, wherein the rotating layer and the polarizing film can be fabricated inside or outside the display unit. 18. The method for manufacturing a reflective polarizing film as claimed in claim 14, wherein the compensation film and the cholesteric liquid crystal layer can be fabricated inside or outside the display unit. 19. The method for manufacturing a reflective polarizing film as claimed in claim 14, wherein the substrate is a transparent substrate or an opaque substrate. 20. The method for manufacturing a reflective polarizing film as claimed in claim 14, wherein the compensation film comprises a λ/4 film.

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