A film 1 for a metal layer laminate board is used for lamination of a metal layer 5. The film 1 for a metal layer laminate board includes a porous resin layer 2 and a skin layer 3 in order in a thickness direction. The porous resin layer 2 has an average pore size W in the entire thickness direction of 7.0 μm or less. The porous resin layer 2 includes a first region 11 to a fifth region 15 disposed in order in a direction away from the skin layer 3 when the porous resin layer 3 is equally divided into five in the thickness direction. A ratio (A1/A5) of an average pore size A1 of the first region 11 to an average pore size A5 of the fifth region 15 is 0.45 or more and 1 or less.

A porous polyimide film has a low dielectric loss tangent. The porous polyimide film is a reaction product of a diamine component and an acid dianhydride component. The diamine component contains an aromatic diamine represented by the following formula (1).

##STR00001##

(In formula, Y represents at least one selected from the group consisting of a single bond, —COO—, —S—, —CH(CH.sub.3)—, —C(CH.sub.3).sub.2—, —CO—, —NH—, and —NHCO—.) The porosity is 50% or more.

A porous polyimide film is provided to suppress an increase in a dielectric loss tangent even when immersed in water. In the porous polyimide film, a difference between a dielectric loss tangent T1 after being left to stand for 24 hours under an atmosphere of 25° C. and relative humidity of 50% and a dielectric loss tangent T2 after immersion in water for 24 hours under an atmosphere of 25° C. is 0.0030 or less.

A method of forming an aromatic polyester polyol compound comprising an imide moiety, wherein the method comprises reacting: (i) a cyclic anhydride compound; (ii) a phthalic acid based compound; (iii) a primary amine compound; and (iv) an aliphatic diol compound.

A method of forming an aromatic polyester polyol compound comprising an imide moiety, wherein the method comprises reacting: (i) a cyclic anhydride compound; (ii) a phthalic acid based compound; (iii) a primary amine compound; and (iv) an aliphatic diol compound.

A photo alignment including a copolymer of a diamine and a dianhydride, wherein the copolymer includes a repeating unit including a first group derived from the diamine and a second group derived from the dianhydride, and wherein any one of the first group and the second group includes a photoreactive group and the other one of the first group and the second group includes at least one selected from a tert-butyl group, a tert-butoxy group, a tert-butyloxycarbonyl group, and a di-tert-butyloxycarbonyl group.

A photo alignment including a copolymer of a diamine and a dianhydride, wherein the copolymer includes a repeating unit including a first group derived from the diamine and a second group derived from the dianhydride, and wherein any one of the first group and the second group includes a photoreactive group and the other one of the first group and the second group includes at least one selected from a tert-butyl group, a tert-butoxy group, a tert-butyloxycarbonyl group, and a di-tert-butyloxycarbonyl group.

A monomer represented by Chemical Formula 1:

##STR00001##

wherein, in Chemical Formula 1, R.sup.1, R.sup.2, A.sup.1, A.sup.2, L.sup.1, L.sup.2, o, p, q, and r are the same as defined in the detailed description.

A monomer represented by Chemical Formula 1:

##STR00001##

wherein, in Chemical Formula 1, R.sup.1, R.sup.2, A.sup.1, A.sup.2, L.sup.1, L.sup.2, o, p, q, and r are the same as defined in the detailed description.

A semi-crystalline biaxially oriented film comprising a copolyester which comprises repeating units derived from an aliphatic glycol, an aromatic dicarboxylic acid, and the monomer of formula (I): (I) wherein n=2, 3 or 4, Z is C═O, and wherein comonomer (I) constitutes a proportion of the glycol fraction of the copolyester and is present in an amount of at least about 4 mol % of the glycol fraction of the copolyester. ##STR00001##