According to one embodiment, a varnish for a photo alignment film includes an imidization promotor and a first polyamic acid-based compound in an organic solvent. The first polyamic acid-based compound is a polyamic acid or a polyamic acid ester. The imidization promotor has skeleton containing no primary amino group and no secondary amino group. The first polyamic acid-based compound has terminal skeletons containing no primary amino group.

A liquid crystal display includes: a first substrate; a second substrate overlapping the first substrate and spaced apart therefrom; a liquid crystal layer between the first substrate and the second substrate and including liquid crystal molecules; a first alignment layer between the first substrate and the liquid crystal layer; and a plurality of protrusions between the first alignment layer and the liquid crystal layer, wherein the first alignment layer includes a photoinitiator, wherein the plurality of protrusions include a polymerization product of the photoinitiator, a reactive mesogen, and a vertical alignment additive, and the vertical alignment additive may be less reactive than the photoinitiator.

A photosensitive resin composition including a polyimide resin (A) having a specific structure and a weight average molecular weight of 70000 or less is provided.

An exemplary embodiment of the present application provides a polyimide resin comprising a structure represented by Chemical Formula 1 and a positive-type photosensitive resin composition comprising the same.

An LED filament and an LED light bulb applying the same are provided. The LED filament includes a conductive section including a conductor; two or more LED sections connected to each other by the conductive section, and each of the LED sections includes two or more LED chips electrically connected to each other through a wire; two electrodes, electrically connected to the LED section; and a light conversion layer with a top layer and a base layer, covering the LED sections, the conductive section and the two electrodes, and a part of each of the two electrodes is exposed respectively. The LED filament is supplied with electric power no more than 8 W, when the LED filament is lit, at least 4 lm of white light is emitted per millimeter of filament length.

In a first aspect, a coating solution includes a soluble polymer and a crosslinking precursor. The soluble polymer includes an imide group. The crosslinking precursor includes a first amine group that is either reactive or passivated towards crosslinking and one or more additional amine groups, wherein the one or more additional amine groups has been passivated towards crosslinking such that the crosslinking precursor can be chemically converted, thermally converted, photo-converted or dissociated to form at least two reactive amines. In a second aspect, a process for forming a polymer film includes: (a) casting a coating solution, (b) activating the crosslinking precursor using an external stimulus to form at least two reactive amines and crosslink the polymer, and (c) drying the polymer film. The coating solution includes a soluble polymer, including an imide group, and a crosslinking precursor.

The embodiments relate to a polyamide-based film that is excellent in optical properties and mechanical properties, to a process for preparing the same, and to a cover window and a display device comprising the same. There are provided a polyamide-based film, which comprises a polyamide-based polymer and has a plasticity characteristic value represented by the following equation of 18.45 to 19.97%, a process for preparing the same, and a cover window and a display device comprising the same: Plasticity characteristic value (%)=(100−nIT)/(HIT/HM). In this equation, nIT, HIT, and HM are measured according to the ISO 14577 standard with a nanoindenter, nIT is the elasticity (%), HIT is the indentation hardness (N/mm.sup.2), and HM is the composite hardness (N/mm.sup.2).

A tetracarboxylic dianhydride that is a mixture of stereoisomers of a compound represented by the following general formula (1):

##STR00001##

[in the formula (1), R.sup.1, R.sup.2, and R.sup.3 each independently represent a hydrogen atom or the like and n is an integer of 0 to 12], wherein a content of an isomer (A) represented by a specific general formula is 40% by mol to 98% by mol relative to a total amount of the stereoisomers, a content of an isomer (B) represented by a specific general formula is 2% by mol to 60% by mol relative to the total amount of the stereoisomers, and a summed amount of the isomers (A) and (B) is 42% by mol or more relative to the total amount of the stereoisomers.

The present invention has the effect of making it possible to produce 1,1,1-trifluoro-2,2-bisarylethane efficiently by a simple procedure by condensing a mixture of fluoral and hydrogen fluoride with an aryl compound under anhydrous conditions. The purity of the 1,1, 1-trifluoro-2, 2-bisarylethane obtained can be raised by a simple purification method such as crystallization or distillation. The obtained 1,1,1-trifluoro-2,2-bisarylethane can be increased in purity by a simple purification method such as crystallization operation or distillation.

The present invention relates to a polymer having excellent liquid crystal alignment and electrical properties and thus is suitable for use as a liquid crystal alignment agent, a liquid crystal alignment agent containing the same, a liquid crystal aligning film formed from the liquid crystal alignment agent, and a liquid crystal display device containing the liquid crystal aligning film.