| 摘要 |
Superior frictional materials are formed by heating under pressure in the presence of a filler, e.g., asbestos, and a source of formaldehyde, e.g., hexamethylenetetramine, the polymers formed by reacting (1) a mixture of compounds selected from the group having the formula R1-A-CH2-OCH2-yA-xCH2-OCH2-yR3 wherein each A is an independently selected aromatic radical having the formula <IMAGE> +tr <IMAGE> WHEREIN EACH R1 represents an independently selected radical from the group consisting of hydrogen, -CH2-OCH2-yR3; each R2 represents an independently selected radical selected from the group consisting of R1, halogen or an alkyl group of 1 to 10 carbon atoms; R3 represents a radical selected from the group consisting of hydrogen, methoxy, ethoxy, propoxy or -A-H; x represents an integer from 0 to 60; y represents an integer from 0 to 4; z represents an integer from 0 to 2; and B represents oxygen or sulfur; provided that if x is 0 and A is diphenyloxide, then y must be 1 or greater; which mixture may contain up to 50% by weight unreacted aromatic HAH; with (2) at least one monomeric reactant selected from the group <IMAGE> WHEREIN R represents hydrogen, alkyl or aryl of 1 to 20 carbon atoms and <IMAGE> M REPRESENTS AN INTEGER FROM 1 TO 3; O REPRESENTS AN INTEGER FROM 1 TO 5; P REPRESENTS AN INTEGER FROM 0 TO 3; B represents oxygen, sulfur or C1 to C3 alkylidene and q represents an integer from 0 to 1; and finally with (3) formaldehyde in the presence of an acid catalyst at a temperature of from between about 90 DEG C to about 190 DEG C for from several minutes to several hours.
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