Patent Application
20050183747
The present application is based on, and claims priority from, Taiwan Application Serial number 93104361, filed Feb. 20, 2004, the disclosure of which is hereby incorporated by reference herein in its entirety.
1. Field of Invention
The present invention relates to a TAC film pre-processing method. More particularly, the present invention relates to a TAC film pre-processing method for reducing the contact angle of water on a TAC film.
2. Description of Related Art
LCD displays are one of the most rapidly developed display technologies in the world. In the field of computer industry, computers having LCD displays occupy a very large market share, Moreover, in the market of home televisions, the ratio of televisions with LCD displays (LCDTV) is growing rapidly. Therefore, LCD displays will play a very important role in the future.
An LCD display includes, for example, a back light module, polarizers, a liquid crystal layer and color filters. A polarizer allows a light that is linearly polarized in a specific direction to pass. When the LCD display is controlled by an external voltage, the LCD display is capable of generating a white mode and a black mode. Thus, the LCD display can be controlled to show images.
Therefore, a polarizer plays an important role in an LCD display. Generally speaking, the structure of a polarizer is made by sandwiching a PVA (poly vinyl alcohol) film between two TAC (cellulose tri-acetate) films. The interface between the PVA film and the TAC film is a hydrophilic interface, so that a more hydrophilic TAC film attaches to the PVA film more easily. Therefore, before the TAC film is attached to the PVA film, the TAC film is be pre-processed to obtain a smaller contact angle of water, i.e. a better hydrophilic character.
It is therefore an objective of the present invention to provide a TAC film pre-processing method that is capable of reducing the contact angle of water on a TAC film.
It is another objective of the present invention to provide a TAC film pre-processing method for reducing the contact angle of water on a TAC film, which method is simple, fast, and greatly reduces the contact angle.
It is still another objective of the present invention to provide a TAC film pre-processing method for reducing the contact angle of water on a TAC film, which method is cheap.
In accordance with the foregoing and other objectives of the present invention, a TAC film pre-processing method for reducing the contact angle of water on a TAC film is provided. The method includes the following steps.
First, a base cleaning process is performed by passing the TAC film through a base tank. Then, a first water cleaning process is performed by passing the TAC film through a first rinse tank. Following that, an acid cleaning process is performed by passing the TAC film through an acid tank. Then, a second water cleaning process is performed by passing the TAC film through a second rinse tank, in which an alcohol is added to the second rinse tank at a predetermined concentration. The base cleaning process, the first water cleaning process, and the acid cleaning process as a whole is called a chemical cleaning process. The alcohol can be methanol, ethanol, or propanol, and is preferably iso-propanol (IPA). In the second rinse tank, the predetermined concentration of the alcohol is from 2% to 100%, and preferably from 4% to 6%.
The invention has at least the following advantages. The TAC film pre-processing method can effectively reduce the contact angle of water on the TAC film. The method is simple, fast and cheap, and is achieved by adding an alcohol to the second rinse tank.
It is to be understood that both the foregoing general description and the following detailed description are examples, and are intended to provide further explanation of the invention as claimed.
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. In the drawings,
Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
Before the TAC film 102, the PVA film 104, and the TAC film 106 are attached together, the TAC film 102 and the TAC film 106 have to be pre-processed, so that the contact angle of water on the TAC film 102 or the TAC film 106 is smaller than 20 degrees. Because the interface between the PVA film 104 and the TAC film 106 is a hydrophilic interface, the contact angle of water on the TAC film 102 or the TAC film 106 should be smaller than 20 degrees for tight cohesion.
Following that, a second acid cleaning process is performed by passing the TAC film through a second acid tank (step 308). The first acid cleaning process combined with the second acid cleaning process is called an acid cleaning process (step 307). The first acid tank and the second acid tank both contain, for example, H2SO4. The concentration of H2SO4 is about 0.1 N in both the first acid tank and the second acid tank. The total acid cleaning process time is about 4 seconds and the temperature is about 25 degrees Celsius.
Then, a second water cleaning process is performed by passing the TAC film through a second rinse tank (step 310). An alcohol is added at a predetermined concentration to the second rinse tank. For example, the alcohol can be methanol, ethanol, or propanol. A preferred alcohol is isopropanol. For example, in the second rinse tank, the predetermined concentration of the alcohol is from 2% to 100%, and preferably from 4% to 6%.
Subsequently, a drying process (step 312) is performed by putting the TAC film into an oven. The temperature is about 100 degrees Celsius and the drying process time is about 10 minutes. Then, a pre-processing process is completed. In an experimental test, the contact angle of water on the TAC film is 17.2 degrees before adding an alcohol to the second rinse tank and 13.2 degrees after adding the alcohol to the second rinse tank. The contact angle is far smaller than the 20-degree requirement. Therefore, the method mentioned above can effectively reduce the contact angle of water on the TAC film.
Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. Therefore, their spirit and scope of the appended claims should not be limited to the description of the preferred embodiments contained herein. It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 93104361 | Feb 2004 | TW | national |
