Introductory Remarks A. C. ELM The New Jersey Zinc Company
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STUDY of the history of human endeavor reveals that the birth and growth of an industry usually follow a definite pattern. Someone discovers, more or less accidentally, a new product or process which offers promise of satisfying a recognized need or of increasing the welfare or comfort of the human race. By tedious and wasteful trial and error methods the inventor finally develops his brain child into an economical process or useful product. His personal skill and experience are necessary for the successful operation of the process or manufacture of the product. This development thus acquires the status of an art. Further development beyond this stage is dependent upon an understanding of the basic principles which make the process work or the fundamental properties which make the product desirable or useful. Research provides the fundamental knowledge needed and development applies this knowledge to the improvement of the product or process, until these operations finally become a science. The development of the industry of organic protective coatings and plastics followed this pattern rather closely. Many still remember the time when every technical operation was Derformed according t o some secret and well guarded formula or recipe, when the varnish maker and paint maker reigned supreme in their domains, and when paint making was as much of an a r t as painting. The invasion of this field by the chemist has changed all this so radically that the old-time varnish and paint makers would hardly recogniPe it today. One typical example may serve to illustrate a development of this type. Phenol-formaldehyde plastics were discovered when a chemist realized that the peculiar properties of the products of some reactions which had plagued organic chemists ever since Woehler’s time might be made to serve a useful purpose. By trial and error methods the first commercial process for the production of phenol-formaldehyde plastics was developed. The similarity between these materials and the natural resins then in use in the varnish industry stimulated efforts t o make soluble phenol-formaldehyde resins which could be used in the manufacture of varnishes. Progress was slow and tedious until chemists began to unravel the basic reactions which led t o the formation
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of resins, and recognized the nature of the resinous state. With the formulation of these basic principles high polymer chemistry was born. This science pointed out numerous ways for the production of other materials possessing the properties that made the early phenol-formaldehyde resins and plastics so desirable. Sparked by the discoveries of the high polymer chemists, t h e plastics industry developed to its present spectacular size in t h e quarter century reviewed here. Developments like these do not just happen. They are born out of the vision of some people imbued with the pioneering spirit which has made this country so great, and out of the enthusiastic pursuit by these people of their ideas, hope, and dreams. In many cases success is slow in coming, and only the courage of their conviction and the faith in their own beliefs keep these pioneers plodding toward their goal. The ccatings industries were fortunate that a band of pioneers 25 years ago saw the necessity of employing scientific methods to their problems, and realized that further growth was contingent upon the full utilization of every bit of help science could offer. As individuals they had labored tirelessly to put operations on a scientifically and technologically sound basis, and their efforts were beginning t o bear fruit. However, they were aware that the full and speedy realization of their hopes would depend upon the organization of a forum where kindred spirits could meet and, freed from the shackles of tradition, could exchange ideas, discuss plans, and think out loud. They knew that the stimulation received by. each individual in these gatherings would more than pay for the bit he contributed to the success of the whole venture. They were fully aware of the value of association with other chemists whose major interests lay in wholly unrelated fields, for it had been shown repeatedly that the successful application of fundamental scientific facts and experiences t o industrial problems is subject t o related general principles regardless of the diversity of the problems involved. They knew that much can be gained from the freshness of thought and the radically different perspective of scientists not in close contact with their own industry. With these ideas in mind they decided to organize the Division of Paint and Varnish Chemistry of the AMERICAN CHEMICAL SOCIETY.
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INDUSTRIAL AND ENGINEERING CHEMISTRY
The division had hardly outgrown its swaddling clothes n-hen the discovery of t>heoil-soluble synthetic resins opened up a new field for its activities. Related raw materials, markets, and theories induced the synthetic resin chemists to take an active interest in the division. In 1937 they were given recognition as a distinct group, but t x o years later decided to affiliate permanently with the Division of Paint and Trarnish Chemistry. In recognition thereof its name was changed to Division of Paint, Varnish, and Plastics Chemistry, and the divisional by-laws mere amended to provide for the election of chairmen alternately from the protective coatings group and the plastics group. The subsequent rapid growth of high polymer chemistry resulted in the influx of a tremendous number of theoretical papers dealing especially with the physical chemistry of polymers, which threatened to drown out the technological aspects of the protective coatings and plastics industries which the division had been founded to foster. To eliminate this conflict this division took the active lead in the organization of the High Polymer
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Forum, which started operations in 1946 and has grown into on(' of the major scientific activities of the . ~ M E R I C A R CHmiIc.ii2
SOCIETY. According to information gathered by Secretary E. E. Mc:Sweeney, the division has held 43 meetings and received i 5 8 papers since its formation 25 years ago. About i 8 % of thew papers fell into four major subject classifications--pigmenti: (12%), oils (15%), resins (as%), and testing (227,). The balance (about 22%) dealt with such diversified suhjects as thinners, paint formulation and application. The anniversary program is based on these four major subjects. They serve to show in what way and how much this division has contributed to the progress of the industries it serves, and to demonstrate its right t'o a share of the credit for the better pigments, oils, resins, plastics, and manufacturing processes available today. -4t the same time it' offers an opportunity to clarify thinking, give a new perspective and incite to still greater cfforts for the benefit of the science and industry.
Progress in the Protective Co and Plastics I ustries
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CONTRIBUTIONS OF THE OIL CHEMIST D. H. WHEELER General Mills, Inc., Minneapolis, Minn.
M o s t protective coatings based on drying oils result from two basic reactions: (1) polymerization by heat (bodied oils) or condensation (alkyds, synthetic oils, certain resin-oil combinations); (2) further polymerization by oxygen, catalyzed by driers, light, or heat. This paper attempts to assign an average functionality to the unsaturated groups in drying oils as they function in heat and oxidative polymerization, and to review what the oil chemist has contributed to understanding the mechanisms by which they exert their functionality, There is a remarlcable general similarity in the heat and oxidative functionality of the unsaturated groups of drying acids, and in the formation of conjugated from nonconjugated groups in both types of polymerization. However, there is evidence of considerable difference between the two types of poIymerization as to.the nature and extent of side reactions and possible structures involved in the polymerization.
HE use of drying oils in protective coatings Can become a T s c i o n c e *&her than an art only when industry the chemical reactions that occur during the processing and application of drying oil products. Therefore, the oil chemist's contribution to knowledge of those reactions is even more important than individual products or processes he has developed. The most important reaction involved in the formation of a hard, tough, and durable protective film is the conversion of a relatively simple compound of low molecular weight into one of extremely large molecular weight and complexity. I n lacquers
and enamels based upon cellulose derivativcs, nature has synthesized the large molecular weight skeleton. The chemist has simply altered their structures so that they may be ,!issolved and spread as a film. To produce other lacquers and enamels, he has built up synthetic resins from simpler units and similarly dissolved and dispersed them. In these types of Iacquer and enamel, the film-forming material is already built to the necessary size before it is deposited as a film; the final film is left when the solvent evaporates. The final film from drying oil protective coatings, on the other hand, usually results from t\vo basic ieactions: (1) an increase in molecular size of the vehicle by heat-induced polymeiization, by copolymerization, or by condensation polymerization (usually completed before the material is deposited as a film): (2) additional polymerization of the deposited film by the action of molecular oxygen, catalyzed by driers with or without the aid of heat and light. In some paints using unpolymerized oil alone as the vehicle, the second reaction is the sole polymerizing mechanism. However, in many exterior paints and in practically all interior paints and enamels, the first reaction represents an important step in Producing finishes that Will dry rapidly a d thoroughly, by oxygen conversion, to produce durable useful fikm AS the oil chemist attempts to build a science that will lead t o an understanding of why and how these two reactions o x u r , his most useful single concept is that of functionality and the part it plays in polymerization reactions.
