Polyester compositions are the reaction product of a reaction mixture including at least two different diacids, and at least two different diols. At least one diacid or diol has at least one pendant ethylenically unsaturated group, and at least one diacid or diol has at least one pendant ionic group. The polyester composition has a glass transition temperature in a range of 60 C. to 12 C., and is a vibration-damping, pressure sensitive adhesive.

The present invention provides an aromatic polyester having several operative functional groups and a method for producing same. An aromatic polyester comprising a polycarboxylic acid component and a polyhydric alcohol component as a copolymerization component, wherein the aromatic polyester comprises a polycarboxylic acid component having an operative functional group by 50 mol % or more when a total amount of the polycarboxylic acid component is taken as 100 mol %, and the aromatic polyester comprises an aromatic polyhydric alcohol component by 50 mol % or more when a total amount of the polyhydric alcohol component is taken as 100 mol %.

A copolyester, comprising structural units represented by [I], [II], [III] and [IV]. The number of structural units represented by [III] is 1-99% of the number of structural units represented by [I], and the number of structural units represented by [IV] is 0-99% of the number of structural units represented by [I]. Also provided are a preparation method therefor and an application thereof. Because an introduced high-temperature self-crosslinking group and an ion group can improve the melt viscosity and the melt intensity during burning of a copolyester, and effectively enhance the char-forming capability of the copolyester, the copolyester exhibits excellent flame retardance and anti-dripping performance. The preparation process for the copolyester is mature, convenient to operate, and easy to control and apply to industrial production. ##STR00001## ##STR00002## ##STR00003## ##STR00004## ##STR00005##

A composition for forming a resist underlayer film that enables the formation of a desired resist pattern; and a method for producing a resist pattern and a method for producing a semiconductor device, each of which uses the composition for forming a resist underlayer film. (In formula (1), A.sup.1, A.sup.2, A.sup.3, A.sup.4, A.sup.5, and A.sup.6 each independently represent a hydrogen atom, methyl group, or ethyl group; Q.sup.1 represents a divalent organic group; R1 represents a tetravalent organic group; and R.sup.2 represents an alkenyl group or alkynyl group having 2-10 carbon atoms.) The film-forming composition contains a solvent and a polymer that has a unit structure given by formula (1).