484 



THE INDIA RUBBER WORLD 



[June 1, 1915. 



hardened with lime, as used in varhish works, is better. In 

 thi ■ compounds the higher the percentage of the binder the 

 b< ii, -i the insulating qualities; of filler, the more fireproof the 

 product. In using asphalts and binders of this class heat is 

 ,,,,! employed, but the binders are dissolved in solvents and 

 1 with the fillers to make a plastic which is cold-molded 

 and afterwards dried to remove the solvenl and thus harden 

 the mass [These products do not resemble hard rubber as 

 elj as thosi before mentioned, bul thej are largely used 

 .- insulators, and while liable to -lunik in drying, yet they 

 can be so made as to be acceptable for many , lasses of work 



CASEIN PI \-l [I S 

 [real deal of work has been done and money spent in 

 the endeavor to produce plastics having a basis of casein. 

 ft doe- not seem to be a promising material, yet many articles, 

 such as billiard balls, have been made from it. 



While casein can be obtained from skim-milk by use of 

 rennet, as in manufacturing cheese, it is customary to use 

 muriatic acid Eoi coagulating when making it commercially. 

 Casein mixed with lime or other alkali and a little water 

 can be molded into a plastic mass which dries very slowly 

 ,,, ., transparent mass nearl) as bard as bone and which can 

 then be turned or otherwise worked. If mixed with tillers 

 and slowly dried it shrinks some, but retains its shape. The 

 great weakness of all these casein articles is their affinity for 

 water. If they lose absolutely all their water they become 

 hard and buttle and are no longer plastic. On the other hand. 

 if subjected to moisture they are liable to absorb it and decaj 

 ],, avoid this casein is treated with formaldehyde, which 

 harden- it and renders it more insoluble. This product, 

 patented, is in use under the name of galalith. Galalith has 

 , introduced in the European market in a variety of 

 is and has been used quite largely. It is a hard, horny- 

 mass which, by the incorporation of pigments and fillers, can 

 onverted into imitation ivory, jet, horn, etc., and into 

 most article- ordinarily made from celluloid. Galalith is un- 



it cellulose is treated with nitric acid, and preferably also 

 sulphuric acid, under certain conditions of time, temperature 

 and concentration, there results a nitrocellulose which, when 

 mixed with camphor, produce- the plastic ordinarily called 

 celluloid, a substance which, though quite inflammable, is 

 not explosive and is largely used for many purposes for 

 which hard rubber is also well adapted. In American pro- 

 duction the wet nitrocellulose is ground up with camphor and 

 the mixture dried and heated, when the camphor enters into 

 -,,lid solution with the nitrocellulose, forming a plastic which 

 may be rolled into sheets and also may be molded, while 

 warm and soft. 



In the manufacture of celluloid there are a number of 



Machining oi Vulcanized Fibre Parts. 



ted by fats and oils, alcohols or dilute acids, but it swells 

 up in alkaline liquids. It is as good an insulator as celluloid 

 and will resist fire, as it chars without melting. It is free 

 from the camphor smell of celluloid, and odorless. 

 i ELLULOID. 

 Celluloid is a plastic which closely resembles hard rubber 

 in some of its valuable qualities. It is tough, flexible and 

 to a remark. ill, extent and can be molded with ease, 

 as when heated it becomes soft. Its great drawback is in- 

 flammability. 



Gun cotton, or the highly nitrated cellulose, was first made 

 in Europe. Dissolved in ether, the solution was known as 

 collodion and was used for photographic films at an early 

 day. 



Delaware Hard Fibre Co. 



I SLENDERING SHEETS OF H.\RD FlBRE. 



processes analogous to those used in rubber manufacture. 

 There is the mixing of the nitrocellulose and camphor on rolls 

 while a little solvent, such as alcohol or ether, is added to 

 keep the mass soft while the rolls are heated to about 50 

 degrees C. Cut sheet is also manufactured from celluloid in 

 a manner very similar to rubber. The celluloid is also calen- 

 dered to give a smooth finish to sheets. The hot molding is 

 done in presses similar to vulcanizing presses. 



Celluloid has one feature favoring it over rubber in that 

 ii is transparent and readily takes any color. Being so easily 

 molded, it is used to imitate horn, ivory, tortoise shell, ebo- 

 nite, etc. 



The mixture of casein with celluloid is said to have met 

 with considerable success, particularly in reducing its in- 

 flammability. 



CONDENSATION PRODUCTS. 



If a phenol or carbolic acid, or body of this nature, is heated 

 with formaldehyde or a similar body, a condensation product 

 is formed with elimination of water, the body first appearing 

 a- ,i heavj oil, then assuming a resinous appearance, all the 

 time becoming harder and more insoluble; and finally, if highly 

 healed, becoming very hard and insoluble, somewhat resem- 

 bling amber in appearance. 



While this general process was long known, it was not until 

 Dr. Baekeland produced Bakelite that it became of commer- 

 cial importance. I lis work resulted in two fundamental dis- 

 coveries: First, he found that in the presence of minute quan- 

 tities of alkali, preferably ammonia, the reaction became con- 

 trollable and wa- greatly hastened, so that the formation of 

 the resins of uniform compositions and properties beam, 

 easy; and, secondly, that if this formation was treated in 

 molds under heat and pressure, the hard insoluble variety 

 free from porositj could be made successfully. 



Before molding it is customary to mix in some kind oi 

 tiller for most objects. Asbestos is a favorite for thi- purpose 

 and when used the product gives good insulation below 2.500 



