A copolymer including a repeating unit represented by (I) wherein: Y is selected from: a carboxylic acid, sulfonic, phosphorous acid and phosphoric acid and their corresponding salt or ester; imino, amide, nitrile, hydrogen, hydroxyl and alkyl comprising from 1 to 6 carbon atoms; and R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are independently selected from: hydrogen, alkyl groups comprising from 1 to 6 carbon atoms, and R.sub.1 and R.sub.2 may collectively form a ketone group or a 9, 9-fluorene group, and R.sub.3 and R.sub.4 may collectively form a ketone group or a 9, 9-fluorene group; R.sub.5 and R.sub.6 are independently selected from: a bond and an alkylene group comprising from 1 to 6 carbon atoms; R.sub.7 is selected from: hydrogen, alkyl, aryl, aralkyl and heteroaryl groups comprising from 1 to 8 carbon atoms which may be unsubstituted or substituted with carboxylic acid, sulfonic acid and phosphoric acid and their corresponding salt or ester, imino and amide; and X and X are independently selected from: a carboxylic acid, sulfonic acid and phosphoric acid and their corresponding salt or ester, imino and amide; nitrile, hydrogen, alkyl having from 1 to 6 carbon atoms and alkoxy having from 1 to 6 carbon atoms.

##STR00001##

A copolymer including a repeating unit represented by (I) wherein: Y is selected from: a carboxylic acid, sulfonic, phosphorous acid and phosphoric acid and their corresponding salt or ester; imino, amide, nitrile, hydrogen, hydroxyl and alkyl comprising from 1 to 6 carbon atoms; and R.sub.1, R.sub.2, R.sub.3, and R.sub.4 are independently selected from: hydrogen, alkyl groups comprising from 1 to 6 carbon atoms, and R.sub.1 and R.sub.2 may collectively form a ketone group or a 9, 9-fluorene group, and R.sub.3 and R.sub.4 may collectively form a ketone group or a 9, 9-fluorene group; R.sub.5 and R.sub.6 are independently selected from: a bond and an alkylene group comprising from 1 to 6 carbon atoms; R.sub.7 is selected from: hydrogen, alkyl, aryl, aralkyl and heteroaryl groups comprising from 1 to 8 carbon atoms which may be unsubstituted or substituted with carboxylic acid, sulfonic acid and phosphoric acid and their corresponding salt or ester, imino and amide; and X and X are independently selected from: a carboxylic acid, sulfonic acid and phosphoric acid and their corresponding salt or ester, imino and amide; nitrile, hydrogen, alkyl having from 1 to 6 carbon atoms and alkoxy having from 1 to 6 carbon atoms.

##STR00001##

A copolymer including a repeating unit represented by Formula I: wherein: L is a divalent hydrocarbon group comprising from 1 to 12 carbon atoms; and L is optional and when present is represented by Formula II: wherein: Y, Y and Y if present, are independently selected from: a carboxylic acid, sulfonic acid, phosphorous acid and phosphoric acid and their corresponding salt or ester; imino, amide, nitrile, hydrogen, hydroxyl and alkyl comprising from 1 to 6 carbon atoms; and A, A and A if present, are independently selected from an arylene moiety, with the proviso one or both Y and A may not be present.

##STR00001##

There are provided a compound containing a phenolic hydroxyl group, which exhibits excellent heat resistance and excellent flame retardancy in terms of a cured product thereof, a phenolic resin including the same, a curable composition and a cured product thereof, a semiconductor sealing material, and a printed circuit board. The phenolic resin contains a binuclear compound (X) represented by the following Structural Formula (I), and a trinuclear compound (Y) represented by the following Structural Formula (II) as essential components: ##STR00001##
wherein each of j and k is 1 or 2, and at least one of j and k is 2; ##STR00002##
wherein each of l, m and n is 1 or 2, and at least one of l, m, and n is 2.

There are provided a compound containing a phenolic hydroxyl group, which exhibits excellent heat resistance and excellent flame retardancy in terms of a cured product thereof, a phenolic resin including the same, a curable composition and a cured product thereof, a semiconductor sealing material, and a printed circuit board. The phenolic resin contains a binuclear compound (X) represented by the following Structural Formula (I), and a trinuclear compound (Y) represented by the following Structural Formula (II) as essential components: ##STR00001##
wherein each of j and k is 1 or 2, and at least one of j and k is 2; ##STR00002##
wherein each of l, m and n is 1 or 2, and at least one of l, m, and n is 2.

A compound represented by the following formula (1).

##STR00001##

(in formula (1), each R.sup.1 independently represents a divalent group having 1 to 30 carbon atoms, each of R.sup.2 to R.sup.7 independently represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a thiol group or a hydroxyl group, in which at least one R.sup.5 represents a hydroxyl group or a thiol group, each of m.sup.2, m.sup.3 and m.sup.6 is independently an integer of 0 to 9, each of m.sup.4 and m.sup.7 is independently an integer of 0 to 8, m.sup.5 is an integer of 1 to 9, n is an integer of 1 to 4, and each of p.sup.2 to p.sup.7 is independently an integer of 0 to 2.)

A compound represented by the following formula (1).

##STR00001##

(in formula (1), each R.sup.1 independently represents a divalent group having 1 to 30 carbon atoms, each of R.sup.2 to R.sup.7 independently represents a linear, branched or cyclic alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, a thiol group or a hydroxyl group, in which at least one R.sup.5 represents a hydroxyl group or a thiol group, each of m.sup.2, m.sup.3 and m.sup.6 is independently an integer of 0 to 9, each of m.sup.4 and m.sup.7 is independently an integer of 0 to 8, m.sup.5 is an integer of 1 to 9, n is an integer of 1 to 4, and each of p.sup.2 to p.sup.7 is independently an integer of 0 to 2.)

A resin powder for solid freeform fabrication has a 50 percent cumulative volume particle diameter of from 5 to 100 m and a ratio (Mv/Mn) of a volume average particle diameter (Mv) to the number average particle diameter (Mn) of 2.50 or less and satisfies at least one of the following conditions (1) to (3): (1): Tmf1>Tmf2 and (Tmf1Tmf2)3 degrees C., both Tmf1 and Tmf2 are measured in differential scanning calorimetry measuring according to ISO 3146, (2): Cd1>Cd2 and (Cd1Cd2)3 percent, both Cd1 and Cd2 are measured in differential scanning calorimetry measuring according to ISO 3146, and (3): C1>C2 and (C1C2)3 percent.

A resin powder for solid freeform fabrication has a 50 percent cumulative volume particle diameter of from 5 to 100 m and a ratio (Mv/Mn) of a volume average particle diameter (Mv) to the number average particle diameter (Mn) of 2.50 or less and satisfies at least one of the following conditions (1) to (3): (1): Tmf1>Tmf2 and (Tmf1Tmf2)3 degrees C., both Tmf1 and Tmf2 are measured in differential scanning calorimetry measuring according to ISO 3146, (2): Cd1>Cd2 and (Cd1Cd2)3 percent, both Cd1 and Cd2 are measured in differential scanning calorimetry measuring according to ISO 3146, and (3): C1>C2 and (C1C2)3 percent.

The invention relates to heat treatment of polymorphic semicrystalline or crystallizable polymers to increase the content of the highest melting crystalline form. Such heat treatment results in a polymer powder that has a consistent, uniform melting range, improved flow and improved durability of the powder particle size for applications that require powder flow at elevated temperatures. In addition to improved powder properties, the articles produced from the powders also exhibit better physical properties in both appearance and in mechanical properties. Thus the invention also includes polymer powders and articles produced by the described processes.