Analysis of Ion Component in Liquid Cristals



One of the causes of a defective display of a liquid crystal display is ionic conduction in the panel. This ionic conduction occurs due to the ions (impurities) having entered the materials such as the liquid crystal material, oriented film and sealing agent or the manufacturing process and depends on their types and concentrations.
The ions that bring about conduction include metal ions, inorganic ions and organic acid.
Generally, the analysis of these is performed by using a method in which ion conductivity is measured and the results of the measurement are converted into the ion concentration. However, the use of capillary electrophoresis equipment makes it possible to separate the ions contained in a liquid crystal and determine them qualitatively and quantitatively.
Furthermore, the study of the results of the determination makes it possible to identify the source of the impurities having entered the liquid crystal and the types of ions that affect it.
Here is a presentation of the results of an analysis (a model test) in which the positive ions having entered liquid a liquid crystal were extracted from the liquid crystal for the purpose of investigating the positive ion substance.

Example of analysis

An electropherogram of a standard sample is shown in the figure on the left.
It is possible to completely separate the positive ion component including methylamines in a short analysis time of 5 minutes or less

mono-MA: monomethylamine
di-MA: dimethylamine
tri-MA: trimethylamine

An electroherogram of the liquid crystal from which ions were extracted is shown in the figure on the left.

Six types of positive ion components, including one unknown component, were detected.

Electropherogram of Liquid crystal If a calibration curve using a standard sample is prepared, it will become possible to conduct a quantitative analysis of the detected components.

Search Number 3002

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