Plasticization and Plasticizer Processes

As servants, piasticizers are more neglected than their masters, the resins them selves. Less has been said and written about ... cohols of a high deg...
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Downloaded by on September 3, 2017 | Publication Date: January 1, 1965 | doi: 10.1021/ba-1965-0048.pr001


piasticizers are often called servants of the resin industry because they serve to soften hard and brittle resins into flexible and pliable products. Of all the resin servants, they are certainly the oldest, as some of them have been used with natural resins far before the first synthetic resin was invented. Their origin dates back to ancient times when the first sailors added oil to pitch when calking their ships. The plasticizer industry represents a giant servant. In 1964, production passed the one billion pound mark. When compared with the plastics industry, piasticizers have only been surpassed by the polyolefins, the vinyls, and the styrene resins. A l l other plastics are smaller, such as the phenolics, alkyds, melamines, ureas, polyesters, or epoxies. As servants, piasticizers are more neglected than their masters, the resins them­ selves. Less has been said and written about them. The Division of Industrial and Engineering Chemistry felt that plasticization and plasticizer processes are important enough to hold a two-day symposium on this subject. This volume contains the papers presented at the symposium during the Spring of 1964— National ACS Meeting in Philadelphia. Piasticizers seem to have an importance equal to plasticized resins and should be considered as a spouse rather than as servant. This couple, resin plus plasticizer, is equally responsible for the physical properties of the plasticized product, its processing performance, and its cost. In selecting a plasticizer, one must consider compatibility, efficiency, permanence, and economy. Compatibility depends upon polarity, structural configuration, and size of molecule. Efficiency depends upon the solvating effect. Permanence depends upon volatility and susceptibility to extraction. And economy depends upon raw materials and conversion costs. Plasticization is the process in which the plasticizer molecules neutralize the secondary valence bonds, known as van der Waal's force between the polymer molecules. It increases the mobility of the polymer chains and reduces the crystallinity. These phenomena become evident in reduced modulus or stiffness, in­ creased elongation and flexibility, and lowering of the brittle or softening tempera­ ture of the plasticized product. The effect of piasticizers on polymers is the sub­ ject of the first chapter by Ε. H . Immergut and H . F. Mark. Reducing the glass transition temperature by blending high boiling solvents with polymers is considered as external plasticization and discussed by M . C. Shen and Α. V . Tobolsky. Reducing the glass transition temperature through copolymerization is considered as internal or self-plasticization. K . Ueberreiter, who created these terms 24 years ago, has recently found a second transition tempera­ ture: the side group transition. Polymers and piasticizers must have side groups of high mobility in order to have plasticizing qualities. This and other observa­ tions, such as the relation between rate of dissolving and solubility are discussed in Ueberreiter's chapter. vli

Platzer; Plasticization and Plasticizer Processes Advances in Chemistry; American Chemical Society: Washington, DC, 1965.

Downloaded by on September 3, 2017 | Publication Date: January 1, 1965 | doi: 10.1021/ba-1965-0048.pr001

In his chapter, "Mobility of Piasticizers in Polymers," R. Kosfeld describes his recent finding that a portion of a liquid plasticizer remains in the liquid-like state in the plasticized resin even below its glass transition temperature. For many years, it has been known that a small quantity of plasticizer acts as an antiplasticizer for polyvinyl chloride (PVC). During a recent search for effective piasticizers for polycarbonate, W. J . Jackson and J . R. Caldwell found several groups of compounds which acted as antipiasticizers. They increased the tensile modulus and strength and reduced the elongation of polycarbonate films. In contrast to piasticizers, these an ti piasticizers affected glass transition tempera­ ture quite differently. Their mechanism is explained by the fact that they either increase crystallinity or reduce the mobility of the polymer chain through the bulkiness of their molecules. Piasticizers represent a large family. There are 300 different piasticizers known, of which one hundred are commercially produced—liquid and solid, monomeric, and polymeric. Piasticizers are generally grouped into phthalates, phos­ phates, low temperature diesters, polymeric or permanent piasticizers, epoxides, and others. U. S . Plastlclzor P r o d u c t i o n 1 9 6 4

Phthalates Phosphates Epoxides Low temperature diesters (adipates, azelates, sebacates) Polymer All others

Million Pounds 650 80 74


Average Price φ/lb. 16 29 29

70 65 96

34 42



Phthalic ester piasticizers represent by far the largest plasticizer group be­ cause of their good performance and economy. In 1964 they accounted for 63% of the total plasticizer production and 46% of their dollar sales. Three chapters of this book describe novel processes for phthalic esters. The chapter by S. J . Fusco and co-workers deals with the oxonation of linear olefins resulting in primary al­ cohols of a high degree of linearity. Phthalate esters of these linear alcohols ex­ hibit an improved performance in PVC compounds. The chapter by L. O. Raether and H . R. Gamrath reports a novel and economic process for phthalic esters by the reaction of phthalic acid with olefins and without isolating the alcohol and even without adding water. The chapter by A . Coenen reveals new catalyst systems for the esterification of phthalic acid with an alcohol. Phosphates represent the second largest plasticizer group. They accounted for 8% of the total plasticizer production and 16% of total sales. Tricresyl phos­ phate continued to hold the lead with production increasing 13% and sales increas­ ing 19%, whereas triphenyl phosphate remained practically constant. Epoxides and low temperature diesters each accounted for 7 % of the total plasticizer market. Epoxidized tallates are frequently replaced by low temperature diesters along with epoxidized soya oil. From the low temperature diesters, adipates and azelates showed a sharp increase, whereas the sebacates decreased. Polymeric piasticizers accounted for 6% of the plasticizer production and enjoy a better than average growth rate. New developments in this area are given in the chapter by H . Hopff. viii

Platzer; Plasticization and Plasticizer Processes Advances in Chemistry; American Chemical Society: Washington, DC, 1965.

Downloaded by on September 3, 2017 | Publication Date: January 1, 1965 | doi: 10.1021/ba-1965-0048.pr001

Because of the many different piasticizers, it frequently becomes important to analyze the composition of a plasticizer extracted from a plastic. A chromato­ graphic method has been developed for analyzing piasticizers by D . Braun and is described in his chapter. Piasticizers are used in combination with cellulosics, vinyls, acrylic, and styrene resins, as well as polyvinylacetate, polyamides, polycarbonate, and other synthetic and natural resins. Because PVC consumes about 70% of all piasticizers produced, the plasticizer market is closely related to the vinyl resins production. During the last ten years, the vinyl market grew at an average rate of 18% per year and has reached 1.6 billion pounds in 1964. The growth in vinyl resins and plasticizer production was paralleled by a drop in resin price and a shift towards more effective and less expensive piasticizers. Chlorinated normal paraffins represent a family of low cost secondary pias­ ticizers for PVC with better properties than chlorinated waxes and are discussed in D. H . Rotenberg's chapter. The interaction between PVC and piasticizers and the effect on mechanical, thermal, and electrical properties are the subjects of the fol­ lowing two chapters by M . C. Shen and Α. V. Tobolsky, H . Breuer and R. Kosfeld, and by R. D . Deanin and co-authors. Large quantities of piasticizers are used .in vinyl plastisols. A novel instrument to measure the gelling characteristics of plastisols is described in A . Hill's chapter. Vinyl organosols will find greater uses in protective coatings, via fluidized-bed spray coating techniques. Little plasticizer is used commercially with styrene polymers. To investigate the interaction between ethylene oxide and vinyl aromatic polymers has been the objective of J . Moacanin and co-workers. The book closes with two chapters on the plasticization and antiplasticization of polycarbonate by A . Conix and L . Jeurissen and G. W. Jackson and J . R. Cald­ well, respectively. It would have been possible to include more examples of the in­ teraction between polymers and piasticizers, for instance on the effect in lacquers, in latices, or adhesives. Some are mentioned in the first chapter. The scope of this book has not been to list all available piasticizers and their combinations with all different kind of resins. For this, we have to refer to the text books and trade literature. The intention of this book and of the symposium has been to report on new developments in the field of plasticization and plasticizer processes. Nobody else would have been more qualified than the authors of these chapters who are experts in this field. It is our hope that this book may lead the reader closer to the achievements of these experts. NORBERT A. J. PLATZER

Springfield, Mass. April 5, 1965

tx Platzer; Plasticization and Plasticizer Processes Advances in Chemistry; American Chemical Society: Washington, DC, 1965.