The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Coloring Finishing And Painting Wood
The vinyl resins have been used to some extent as binding material in molding plastics, but their general use is limited. These resins can be manufactured in an almost colorless and transparent form. Varnishes have been made from vinyl resins for use on objects of metal and sometimes for fabrics.
326. The Important Synthetic Resins.—Many new synthetic resins have been produced, but only a few of them are of much value. The few that are valuable at the present time are really very precious because they are needed to replace natural resins which are now scarce. A few of the best known synthetic resins will be mentioned and described here. Others of some value are known and are being used to some extent.
Amber oh.—The amberols, Fig. 24, are of the phenolformaldehyde type but are often modified or used in combination with other resins which supply qualities not found in the pure resins. The resins commonly chosen to modify the 100% resins into various Albertols or Amberols are often rosin, rosin-esters or ester-gum, and sometimes natural rosins. The addition of cheap, common rosin to the pure phenol-formaldehyde resin produces a new resin characterized by hardness, better oil solubility, greater durability, and less tendency to turn yellow in transparent films. Several grades of Amberol are manufactured having varying characteristics of hardness, different acid numbers, and other physical properties, such as oil solubility and the temperatures used when dissolving in oils. The important Amberols, except No. 226, are not soluble in alcohol, but they are soluble in most of the usual varnish solvents, as turpentine, mineral thinner, and toluol.
Bakelite.—The synthetic material known as Bakelite is the discovery of Dr. L. H. Bakeland and has been used in some of its forms for about a quarter of a century. He discovered that an amber-colored, resin-like material could he produced from phenol and formaldehyde by joining them under certain conditions. Bakelite is now well known for its use in plastics and molded material—even for the telephone and parts of the automobile.
