A liquid crystal light control element that controls a light absorption state by voltage application, the liquid crystal light control element including: a liquid crystal layer containing a liquid crystal composition between a pair of substrates each having an electrode; and a liquid crystal alignment film that is provided on at least one of the substrates and aligns a liquid crystal vertically, wherein the liquid crystal composition contains a liquid crystal and a dichroic dye, the liquid crystal alignment film is obtained from a liquid crystal aligning agent containing a polyimide precursor in which a diamine having a specific side chain is used as a part of the raw material or a polyimide obtained by imidizing the polyimide precursor, and the proportion of the diamine used is 50 to 100 mol % based on the entire diamine component.

A polymer being a product of reactants including a diamine and a monomer represented by Chemical Formula 1: ##STR00001##
wherein, in Chemical Formula 1, R.sup.1, R.sup.2, o, p, L.sup.1, A.sup.1, R.sup.a, m, and n are the same as defined in the detailed description.

The resin composition according to one aspect is a resin composition containing a polyamic acid and a solvent, wherein the polyamic acid has a repeating unit represented by the following general formula (1) in a molecular chain, and the molecular chain has a structure represented by the following general formula (2) at one end or both ends. The proportion of the structure represented by the following general formula (2) relative to 1 mol of the repeating unit represented by the following general formula (1) is 0.001 mol or more and 0.1 mol or less. In the following general formulas, R.sup.1 is a tetravalent organic group; R.sup.2 is a divalent organic group; and R.sup.3 is an organic group having 15 or less carbon atoms.

##STR00001##

A polyimide copolymer according to an embodiment of the present disclosure includes a plurality of structural units. The plurality of structural units include a structural unit derived from dianhydride having an alicyclic structure and a structural unit derived from aromatic diamine including an ether group, thereby mechanical properties, thermal stability and optical characteristics of the polyimide film may be improved.

The present disclosure relates to a polyimide precursor and flexible polyimide obtained by imidization of the polyimide precursor and having high transparency, high glass transition temperature and low coefficient of thermal expansion.

In a first aspect, a polymer film includes a polyimide. The polyimide includes one or more dianhydrides and one or more diamines. Each of the dianhydrides and diamines is selected from the group consisting of crankshaft monomers, flexible monomers, rigid rotational monomers, rigid non-rotational monomers, and rotational inhibitor monomers. The polymer film has a D.sub.f of 0.005 or less, a water absorption of 2.0% or less and a water vapor transport rate of 50 (g×mil)/(m.sup.2×day) or less. In a second aspect, a metal-clad laminate includes the polymer film of first aspect and a first metal layer adhered to a first outer surface of the polymer film. In a third aspect, an electronic device includes the polymer film of the first aspect.

A polyimide film contains fluorinated substituents and cardo structures. The polyimide film exhibits excellent heat-resistance, transparency and mechanical properties. The polyimide film has a glass-transition temperature (Tg) of at least 360° C., a coefficient of thermal expansion (CTE) of 50 ppm/° C. or lower, a modulus of at least 4.0 Gpa, a b* value of 5 or lower and yellowness index of 8 or less. The polyimide film can be used as a display substrate or an optical film in a liquid crystal display (LCD), an organic light-emitting diode (OLED) and in other fields where the characteristic features are required.

Provided is a layered product that uses a high temperature-resistant transparent film having sufficient heat resistance, and that is capable of being mechanically released from an inorganic substrate after various processes are performed on the inorganic substrate since the adhesive strength between the high temperature-resistant transparent film and the inorganic substrate is appropriately weak, and that is less warped along with the inorganic substrate. In this layered product, no adhesive is used between the high temperature-resistant transparent film and the inorganic substrate, the release strength between the high temperature-resistant transparent film and the inorganic substrate is at most 0.3 N/cm, and the warpage amount of the layered product when heated at 300° C. is at most 400 .Math.m.

According to the present invention, a power module that has a base to which a power semiconductor device is bonded and a sealing body for sealing said base and in which the base and the sealing body are bonded with a primer layer interposed therebetween, said primer layer being formed of a cured product of a silicone-modified polyimide resin composition containing, for example, components (A) to (E) below, has high reliability because delamination of an epoxy sealing resin under high temperature conditions is suppressed. (A) Silicone-modified polyimide resin represented by formula (1)
Ee-Ff-Gg  (1)
E is represented by formula (2), F is represented by formula (3), G is a divalent group derived from diamine, f+e+g=100 mol %, the molar ratio f/(e+g) is 0.9-1.1, and e is 1-90 when the sum of e and g is 100. ##STR00001##
R.sup.A is a divalent hydrocarbon group, R.sup.1 and R.sup.2 are alkyl groups, R.sup.3 and R.sup.4 are monovalent aliphatic hydrocarbon groups, R.sup.5 and R.sup.6 are aryl groups or the like, m is an integer of 0-20, n is an integer of 1-20, o is an integer of 0-20, and m+n+o is an integer of 1-30.
-Im-X-Im-  (3)
Im is a cyclic group including a cyclic imide structure, and X is a single bond or the like. (Bc) Heat-decomposable radical initiator (C) Solvent (D) Antioxidant (E) Fumed silica.

A method of making polyetherimide comprising reacting a first diamine having four bonds between the amine groups, a second diamine having greater than or equal to five bonds between the amine groups, 4-halophthalic anhydride and 3-halophthalic in the presence of a solvent and a polymer additive to produce a mixture comprising 3,3′-bis(halophthalimide)s, 3,4′-bis(halophthalimide)s, 4,4′-bis(halophthalimide)s, solvent and the polymer additive wherein the molar ratio of 3-halophthalic anhydride to 4-halophthalic anhydride is 98:02 to 50:50 and the molar ratio of the first diamine to the second diamine is 98:02 to 02:98; and reacting the mixture with an alkali metal salt of a dihydroxy aromatic compound to produce a polyetherimide having a cyclics content less than or equal to 5 weight percent, based on the total weight of the polyetherimide, wherein the polymer additive dissolves in the solvent at the imidization reaction temperature and pressure.