Mobile room-temperature stable acid catalyzed phenol formaldehyde resin compositions

Abstract

Abstract Thermosetting phenol-formaldehyde resins having novel structures and properties are described. In one embodiment, there is provided a novel thermosetting phenol-formaldehyde resin having benzyl ether linkages ortho to the phenolic hydroxyl group and characterized by its infra-red spectrum which exhibits absorption at wave numbers of about 1010 cm -1 , 1060 cm -1 and 1230 cm -1 . The infra-red spectrum has a particular ratio of absorbance at 1010 cm -1 , measured from a base line drawn between wave numbers of 1030 cm -1 and 950 cm -1 , to that at 1230 cm -1 , measured from a base line drawn between wave numbers of 1130 cm -1 and 1310 cm -1 which is less than about 0.1. These novel resins are prepared by the controlled addition of strong acids to thermosetting phenol-formaldehyde resins having the benzyl ether linkages and an infra-red spectrum exhibiting large adsorption at wave numbers of 1230 cm -1 , 1060 cm -1 and 1010 cm -1 , causing a decrease of at least 35% in the ratio of absorbance at 1010 cm -1 , measured from a base line drawn between wave numbers of 1030 cm -1 and 950 cm -1 to that at 1230 cm -1 , measured from a base line drawn between wave numbers of 1130 cm -1 and 1310 cm -1 , while leaving substantially unaltered the absorbance at wave numbers of 1230 cm -1 and 1060 cm -1 . These novel resins are capable of many applications and are normally tack-free, although the tack may be controlled by the addition of an organic solvent, such as phenol, thereto. In a second embodiment, the resins are formed at a mole ratio of formaldehyde to phenol of above 1.7:1 in an aqueous reaction medium. The resins form acid-catalyzed, room-temperature stable and mobile resins which may be applied as a one component curable system onto substrates for the formation of molded articles, such as rice husk boards.

Inventors

• 👤 Ramesh C. Vasishth
• 👤 Pitchaiya Chandramouli

Bibliographic Details