JPS6253809B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an alignment treatment film for a plastic panel in which a transparent conductive film such as indium oxide is provided on plastic. The purpose of the present invention is to obtain a stable horizontal alignment effect on conductive films and plastic substrates. Most conventional liquid crystal display panels use inorganic glass as a substrate, and there are very few liquid crystal display panels that use plastic as a substrate. The alignment treatment film on the conductive film cannot be created by simply transferring the method used for conventional inorganic glass to the plastic panel.
Horizontal alignment stability of liquid crystal cannot be obtained. For example, there is a method of using an organic aminosilane coupling agent as a horizontal alignment treatment agent for an inorganic glass panel in which tin oxide is used as a conductive film on inorganic glass. Even if this alignment treatment agent is used for plastic panels using indium oxide as the conductive film on polyester film,
Liquid crystals are not oriented. This is because the organic silane coupling agent is easily affected by the conductive film. Also, with the tilted evaporation method used for inorganic glass panels,
When SiO is deposited on the above plastic panel, the liquid crystal is oriented on the conductive film and the panel substrate immediately after the deposition, but there are two drawbacks. One of these is the lack of adhesion between the vapor-deposited SiO film and the panel, which is moisture permeable and air permeable, resulting in poor orientation and air bubbles entering the panel due to changes over time. The other problem is that the panels are made of plastic and cannot be fired at high temperatures, which means that the chemically unstable SiO cannot be converted into stable _SiO2 , which is highly hygroscopic and causes poor orientation. be. Another method for horizontally aligning inorganic glass is to form an imide ring-containing polymer, which is a high-molecular substance unaffected by the conductive film, on the conductive film as an alignment film, and then rub the film with cotton cloth or the like. This method had the disadvantage that it could not be used for plastic panels because it required a high temperature of 300°C or higher to form the imide ring-containing polymer. The oriented film of the addition polymerized thermosetting resin of organic cyanate and bismaleimide according to the present invention is as follows.
The features (1), (2), and (3) can eliminate the drawbacks of conventional plastic panel orientation processing methods. (1) The alignment film resin of the present invention is a polymeric substance that is not affected by a conductive film, unlike organic silane coupling agents and the like. (2) The alignment film resin of the present invention has strong adhesion to plastic panels and is chemically and thermally stable, so it has excellent moisture permeability and moisture absorption properties that were observed when forming a SiO film using an inclined vapor deposition method. Also, there is no air permeability, and there is no orientation defect due to aging and no air bubbles mixed into the panel. (3) A high temperature of 300°C or higher was required to form the imide ring-containing polymer, but since the temperature for forming the alignment film resin of the present invention is a low temperature of 150°C or lower, the plastic is thermally Endure. The organic cyanate used in the present invention generally has the formula 1
It is an organic compound represented by Formula 1 Furthermore, bismaleimide is generally an organic compound represented by formula 2. Formula 2 The method for forming the addition polymerized thermosetting resin of organic cyanate and bismaleimide on a plastic panel is to immerse the panel in a solution of organic cyanate and bismaleimide dissolved in a ketone solvent, or to spray the solution onto the panel. Afterwards, the solvent is removed by hot air drying or the like, and the mixture is baked at a temperature and time necessary for the addition polymerization reaction. Lightly rub the fired resin thin film with cotton cloth, etc.
By encapsulating liquid crystal, a liquid crystal display panel with a stable horizontal alignment film according to the present invention can be obtained. A sectional view showing the structure of a liquid crystal display panel according to the present invention is shown in FIG. Reference numeral 1 denotes a plastic substrate, and the material is generally a plastic such as polyester, polycarbonate, or polyether self-on. 2
is a transparent conductive film made of indium oxide containing a small amount of tin. A vacuum evaporation method is used as a method for providing this conductive film on a substrate. In order to improve the adhesion between the substrate and the conductive film, a method is used in which the substrate is undercoated with an organic silane coupling agent in advance. Furthermore, it is also possible to improve the properties by heat treatment or anodic oxidation. 3 is a sealant that serves to hold the panel and seal the liquid crystal. 4 is a nematic type liquid crystal, and azoxy type liquid crystal, biphenyl type liquid crystal, Schiff type liquid crystal, phenylbenzoate type liquid crystal, etc. are used. 5 is an alignment treatment film according to the present invention, which is made of an addition polymerized thermosetting resin of organic cyanate and bismaleimide. Hereinafter, the present invention will be explained in more detail with reference to Examples. <Example> A 0.1% BT resin solution having the composition shown in Table 1 (BT resin is a mixture of organic cyanate and bismaleimide manufactured by Mitsubishi Gas Chemical Co., Ltd. is the trade name of an addition-polymerized thermosetting resin whose main raw material is ), and the solvent is removed by hot air drying at 70°C. Further baking at 150℃ for 30 minutes

[Table] After using acetone as the solvent, rub the panel lightly with a cotton cloth and remove the biphenyl liquid crystal (BDH, E-
7) was sealed to test the initial alignment of the liquid crystal in the absence of an electric field and the horizontal alignment stability against heat and moisture. Table 2 shows the test results. No air bubbles were generated within the panel after any of the tests. In addition, after the rubbing that is performed before liquid crystal filling is strengthened,

[Table] There was no change in the alignment effect after each test, and it can be judged that the adhesion between the alignment film and the substrate was sufficient. The purpose of the present invention is to obtain a stable horizontal alignment effect on a conductive film and a plastic substrate by using an addition-polymerized thermosetting resin of organic cyanate and bismaleimide in the horizontal alignment treatment film of a plastic panel. It does not matter how the addition polymerization type thermosetting resin is formed on the panel. Furthermore, the alignment treatment film of the present invention can be used not only for nematic type liquid crystals but also for plastic panels using smesteric type liquid crystals, cholesteric type liquid crystals, etc., and the same effect can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the construction of a plastic panel according to the present invention.

Claims (1)

[Claims] 1. A liquid crystal display panel whose panel substrate is a substrate made of plastic with a transparent conductive film such as indium oxide, characterized in that an addition polymerized thermosetting resin of organic cyanate and bismaleimide is used as an alignment treatment film. panel.