INTERESTING PRODUCTS AND NEW DEVELOPMENTS OF THE GENERAL ELECTRIC CHEMICAL DIVISION' KURT C. FRISCH General Electric Company, Pittsfield, Massachusetts
G E N E R A L Electric has been active in the chemical field since 1900 when the Company established the first industrial research laboratory in the nation. The main efforts a t that time were mainly directed a t chemical progress as a means of making better electrical products. Taking into account the rapid growth and expansion of chemical products the Chemical Division was formed in 1915 with headquarters a t Pittsfield, Massachusetts. Today the Division has four operating departments. They are the Chemical Materials Department with units in Pittsfield, Massachusetts, Schenectady, New York; and Anaheim, California; the Plastics Department in Pittsfield, Springfield, and Taunton, Massachusetts, and Decatur, Illinois; the Laminated and Insulating Products Department in Schenectady and Coshocton, Ohio; and finally the Silicone Products Department in Waterford, New York. Plastics materials in form of resins or in form of finished products and products closely allied to them, such as surface coatings and plasticizers, represent the major portion of the business done by the Chemical Division, and I will discuss primarily some developments in these fields. Both thermoplastic and thermosetting materials are being either manufactured or fabricated by G. E. The term thermoplastic indicates, as the name implies, that the material softens under the influence of heat and therefore products made of thermoplastic materials can be remolded. The principal thermoplastic materials are polystyrene, vinyls, acrylics, cellulosics, polyethylene, and polyamides (Nylon). Both injection molding and extrusion of thermoplastic materials is carried out by G. E. Injection molding, which is by far the most popular method for molding thermoplastic materials, is the process in which the moldmg compound is made plastic in a heating chamber from which it is forced by high pressure and introduced into a closed mold which is cooled by means 1 Abstract of a n address presented a t the 265th meeting of the NEACT, Deerfield Academy, Deerfield, Mass., April 12, 1952.
of circulating water. The pressure applied to the compound in the heating cylinder is transmitted to the mold after it has been filled. The pressure is held until the compound has solidified. Then the mold is opened and the pieces are removed. Examples of injection molded thermoplastic products are television screens and refrigerator inner doors made of polystyrene. The latter are probably the largest existing injection molded parts in the world. Nylon is also manufactured i n the form of injection molded pieces, such as the gears illustrated. Nylon possesses some advantages of both the thermoplastic and thermosetting molding materials by being heat resistant (some moldings ale dimensionally stable even above 400°F.) and extremely tough at the same time. While the cost of the molding powders is a t present relatively high, Nylon can be molded in thin sections which are very strong and, combined with their shorter molding cycle, the cost factor can partly be countered by these properties. Extrusion is the process of rendering a material plastic and then forcing it through a die and producing tubular or solid articles having the cross sections of the shape of the die opening but indefinite in length. .4 material frequently used is polyethylene. Like polystyrene it has excellent electrical properties and its chemical inertness and toughness make it a material of a wide range of usefulness. Typical applications include insulation for radar and coaxial cables, food packaging, and many others. At present G. E. is running tests on a farm using polyethylene tubing to pump water from a well and it does not take too much imagination to picture the use of plastic tubing, either of polyethylene or similar materials, for transporting various gases and fluids, in radiant heating, and in many other applications. In contrast to the thermoplastic materials thermosetting means that heat sets this type of material or, in other terms, when these materials are subjected to heat and Pressure, a chemical change "curing2' takes lace. Once a thermosetting material is cured it cannot be
468
SEPTEMBER, 1952
changed hack into its original condition. The principal kinds of thermosetting resins are the phenolics, ureas, melamines, alkyds, certain polyesters, and silicones. Of these G. E. manufactures phenolic, alkyd, polyester, and silirone resins while it only processes the other resins. Phenol-formaldehyde resins represent amajor portion of the thermosetting business. Molded applications such as radio cabinets, toaster bases, camera housings, etc., have grown to include bigger and bigger applications such as television cabinets or the new airconditiouing housing shown in t,he figure. This is made of woodflour-filled general purpose phenol-forma l d e h ~ l ecompound. A great step fonvard was made when Hycar2, the synthetic n ~ b b e rmade by copolymerization of hutadiene and acrylonitrile, %.as incorporated into phenolic resins. The rubber increases the resilience and shock resistance of the compound considerably and molded applications are particularly well suited for uses re-
Window Air-cond',ti.ning
Housing Mad. Cornpound
from Phonolis Molding
brand-new development, the "Monotop" laminates. In contrast to older kitchen counter tops or table surfaces, Monotop resists severe abrasions and there is very little in normal everyday kitchen usage that vill so much as dim the beauty of the Monotop surface. Another form in which phenolic resins are being utilized are in surface coatings. I t has been estimated that approximately six billion dollars are lost annually in this country because of corrosion and this situation is the more serious in viem of the tight metal situation. R-108, a new concept in protective coating intermediates, was developed as the result of a study of the basic processes involved in the phenol-formaldehyde con-
Injection Molded N y l a n Gea.. for Oscilleting ran. coat Reduction Ie Effected by Replacement of More Expensive Metal Gears.
quiring exceptionally high impact resistance. Applications of these modified phenolics include soldering guns, various tool handles, faubases, impellers for automatic dishwashers, and many others. So far I have mentioned only molded applications of phenolics. Another important form in which phenolics, or for that matter, other plastics occur, are laminates. Thermosetting resins in solution can be used to impregnate cloth, paper, and various other materials. They are then dried and cut into sheets. I n this form they are ready for the laminating press which cures several layers of these sheets into one single sheet of laminate. In addition to industrial laminates decorative laminates dake the limelight of attraction. Urea and melamine resins are often used in conjunction with phenolic resins to produce decorative laminates such as the
* B. F. Goodrich Chemical Co., Reg. U. 5.Patent OR.
silicon. oil.
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JOURNAL OF CHEMICAL EDUCATION
470
densations. It combines excellent acid and alkali resistance with toughness, flexibility, adhesion, and heat resistance and may be formulated in a variety of coating applications. An interesting application of phenolic resins which is growing in ever increasing popularity is as a binder for sandcores which are used in the manufacture of castings. I t is based on a new foundry process developed in Germany in the late forties, and is called Shell Molding. Only a relatively small amount of resin is necessary to give the sandcore the desired consistency. The sandshells into which the molten metal is poured can be produced at a faster rate and advantages include savings in sand, metal, and labor besides the fact that closer tolerances can be met. Some forecasts indicate that this application may grow in the next ten years to such proportions that more phenolic resins will be used by it than for plastics molding compounds. An unusual application of phenolics is G. E. phenolic foam. It is a cellular thermosetting plastic product produced from special phenolic foaming resins for use as a thermal and acoustical insulator. I t combines excellent insulating properties with light weight. It is sold commercially in form of liquid resins for "foamingin-place" operations. Properly activated this resin expands up to 150 times its original volume, solidifying almost immediately to a rigid, cellular structure which fills completely the space in which it is formed. This self-fabricating property enables it to be made in intricate shapes as well as standard block forms. .4mong the most interesting products which recently made headlines are certain polyester resins. They are
usually made from ethylene glycol and maleic and phthalic anhydrides in various proportions and are then crosslinked with diallylphthalate or styrene. These polyesters are primarily used for the manufacture of so-called "reinforced plastics." In many respects these materials are the glamour products of t,he plastics industry. They soared into prominence during World War I1 when glass-reinforced polyesters were used to manufacture helmets and other military applications. Glass mat is put around a mold over which the resin is poured. It is then allowed to cure at room temperature. Afterward the finished board is sprayed to give it the desired color shade. The same type of materials can be used in the manufacture of boats, luggage, and even automobile bodies. At the recent National Plastics Exposition in Convention Hall, Philadelphia, a plastic auto body was displayed, made of glass-fiber reinforced polyester resins. I t was built by simply putting a few layers of Fiberglass fabric into a hollow mold, painting on 15 gallons of the resin, and letting the thin shell harden overnight. The body is said to be dent- and rust-proof, and, for its \\-eight, stronger than steel. If there is a break in the body caused by a heavy collision, the repair work can be done easily by the motorist himself by simply applying some glass mat and resinon that spot and smoothingthepatch with squeegee. The patch is then painted. The cost of such repair work is only nominal. Despite this happy outlook it will probably take some time before the automobile industry, which has invested a considerable amount of money in machine tools, dies, and skilled labor, will change - over to ulastic bodies. A relatively new field, at least so far as commercial ex~loitationroes, are the silicones. Today silicones are prepared mainly by the "direct process," developed by E. Rochow. This process consists of reacting alkyl or aryl halides, principally the chlorides, xvith a mixture of powdered silicon and metallic copper or silver as a catalyst. When using methyl chloride the predominant reaction can be represented as folloms: In addition to 2 CH,CI
+ Si
-
(CH&3iCl? (1)
the dimethyldichlorosilane (I) other chlorosilanes such as (CH3),SiCland CH3SiCI3are formed in this reaction. The chlorosilanes are then hydrolyzed to yield at first silanols (11) and siloxanediols (111) which then can be condensed to polysiloxanes (173 which are termed commercially silicones:
Comp..rison of Two Coated Steel Test Probes After Exposun to 18 c e n t cau.tic solution 195% ~ h - 0 ~ -t h . ~ . f t ~ a .covend **h a Conventiond Phenolic Coatins. Larted but 30 ~ i n ~ t . ~ha. One on the Right. Coated with R-108 Coating Intermediate. Showed No D-terioration at tha Timo the Test, Wa. Discontinued Five Months
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The outstanding ropert ties of silicones are resistance to high and low temperatures (they resist temperatures as high as 550°F. and as low as - 12OoF.,) outstanding release from--sticking, unusual surface characteristics,
SEPTEMBER. 1952
and inertness. The principal forms in which silicones occur are silicone rubber, water repellents, silicone resins, and silicone oils and greases. You are probably familiar with the clown of the silicone family, the bouncing putty, at one time merely a laboratory curios it,^, hut now going into the center of golf balls as well as in automat,ic leveling devices for table legs. Silicone rubber, while exhibiting not as great physical st,rength and abrasion resistance a t ordinary temperatures as most natural and synthetic rubber stocks, possesses mechanical properties far superior after exposure at elevated temperatures. These properties have led to the use of silicone rubber in lighting equipment, aircraft engines, electrical apparatus, and chemical processing equipment, just t o ment,ion a few applications. The property of silicones to release from sticking is being utilized to release rubber and plastics from molds and hread from baking pans. Silicone oils exhibit only a small change in viscosity over a wide temperahre range. This property can be demonstrated by comparing a silicone oil with a petroleum oil of like viscosity (at room temperature). On chilling t,hese tmo oils to a temperature of - 100°F. the petroleum oil stiffens and congeals while the silicone oil can he poured without any difficulty (see the figure). Silicone oils are being used as damping fluids in internal combustion engines and as lubricating fluids in aircraft gun charging motors among other applications. I mentioned before the unusual surface characteristics of silicones. One of the most important is water repellency. A blotter partly treated with silicone resin and then dipped in water illustrates this property. A more practical application is the treatment of concrete hlocks with silicone resin. Untreat,ed concrete absorbs water easily, hut water runs off the treated blocks. This application bas of course a big potential market for t,heprotection of residential and industrial buildings. Resistance to sunlight and weathering in silicones has been utilized in the manufacture of car polishes which are easier to apply and eliminate "rainbow" streaks so common in ordinary car polishes. Finally, a new development in the mica field will be described. Mica, or more exactly in its form as Muscovite, is an outstanding material in the electrical insulation field. Muscovite, a potassium-aluminum silicate, occurs in t , ~ forms, o a green and a ruby, the main difference being the higher iron content of the green form. The best grade of mica comes from India while the native mica is usually contaminated with
471
~i~~ M*+ E ~ ~ F , , ~ , , , from , a hi^^ where ~i~~~~ converted into continuous sheets of M ~ C = ~.
rlakesf i e outstanding ~
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Insulation Renrtano.
other minerals. G. E. has now brought out, a continous sheet of mica, called mica mat, xvhich permits the use of low-grade domestic mica and may free our mica industry from dependence on foreign sources and alleviate a serious shortage threat to.the electrical industry. Mica mat is 100 per cent mica in the form of flakes and particles in continuous sheets. I t gives better performance than present machine- and handlaid mica because of its greater uniformity of thickness and void-free construction. Mica mat, a-hen impregnated with resins and bonded to paper, glass, or cloth for greater strength, can be used in form of tapes or sheets in heating devices, molded into shapes for motors and generators, or machine-wrapped on bars ' and cable. In conclusion I mould like to point out that the products which I have discussed are merely some outstanding examples of the more recent developments in the Chemical Division. They are the result of a teamwork between research, engineering, and manufacturing which lay the groundwork for t,he new chemical products of the future.
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