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UNITED STATES PATENT OFFICE 2,362,511 Modified GLYCOLIDE RESENS Wilber O

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UNITED STATES PATENT OFFICE 2,362,511 Modified GLYCOLIDE RESENS Wilber O Patented Nov. 14, 1944 2,362,511 UNITED STATES PATENT OFFICE 2,362,511 MoDIFIED GLYCOLIDE RESENS Wilber O. Teeters, Roselle, Del, assignor to E. du Pont de Nemours & Company, Wilmington, Del, a corporation of Delaware No Drawing. Application November 21, 1939, . Serial No. 305,474 4 Claims. (C. 260-8) This invention relates to the modification of acetic acid (glycocol), amino propionic acid, glycolide resins and, more particularly, to the aminobutyric acid, amino benzoic acid, and high preparation of polyglycolide resins having highly er amino aliphatic and aromatic acids, the poly useful physical and chemical properties. peptides may likewise be used, as well as the bi When glycolic acid is dehydrated to a poly functional compound obtained by the partial in glycolide there is obtained a dense, brittle, res teraction of phthalic anhydride and polyhydric inous product which is water-sensitive, insoluble alcohol. With rosin as illustrated by Examples 2 in common organic solvents and incompatible and 4 leaving a free hydroxyl and a free carboxyl with most resinous materials. While it may be gOl. saponified with alkalies, thereby giving a salt that The modification may be effected by adding the is soluble, nevertheless, the resin per se prepared O desired amount of the modifying agent to the by simple dehydration of glycolic acid is of such glycolic acid prior to dehydration. The resulting nature that its utility is considerably limited due, mixture is heated to a temperature of in the principally, to its lack of solubility. Moreover, neighborhood of 150° to 300° C. and held at that the polyglycolide resin is translucent, and, ac temperature until substantially all of the Water cordingly, because of its appearance and chemical 5 has been driven off, which will require in the properties, is not particularly fitted for many uses neighborhood of from 1 to 5 hours. As would be in the artS. expected, the duration of heating and the amount An object of the present invention is to provide of the modifying agent added will be governed a method of modifying the physical characteris in large measure by the particular modifying tics of polyglycolide (dehydrated glycolic, acid). agent used, but it has been found that, generally A further object of the invention is to provide Speaking, 20% by Weight of the modifying agent modifying agents which will convert the Water will convert the opalescent-like polyglycolide to sensitive, relatively insoluble polyglycolide to a a Substantially transparent product, and if the modified polyglycolide which is water-insensitive amount is increased up to 40 to 55% of the mod and soluble in organic solvents. Yet another ob ifying agent, excellent solubilities result and wa ject is to provide a method whereby glycolic acid ter-Sensitivity disappears. is dehydrated in the presence of an Organic Com The modifying agents which may be added to pound having birfurictional groups. A further give the above desired properties to polyglycolide object is to provide new compositions of matter 3) include lactic acid, tartaric acid, citric acid, gly which may be characterized as modified poly ceric acid, tartronic, malic, racemic, ox-hydroxy Collides. isobutyric acid, butyro-lactone and capro-lactone, It has been found that the above and other as Well as their analogues and homologues. objects of the invention can be realized by incor Other modified polyglycolides which are of spe porating into the polyglycolide molecule modify 35. cial interest are those in which the modifying in ing agents which have bi-functional groups. By gredients selected produce a desired effect. For bi-functional groupS is meant the modifying example, addition of a long chain fatty acid to agent contains active groupS that will react with a reaction mixture containing glycolic acid and the hydroxyl and carboxyl groups of the poly a partially condensed phthalic-glyceride (which glycolide. Examples of Such compounds are lac O can be considered as a bi-functional compound) tic acid, tartaric acid and like hydroxy-carboxylic prior to condensation increases the oil and hydro acids. It appears that when compounds having carbon Solubility and decreases the water-sensi th. Se bi-functional groups are heated together tivity of the completely condensed resin. Exam With glycolic acid, and the heating continued ples of fatty acids are lauric, oleic, stearic, cot until Substantially no more Water is given off, 45 tonseed, oil acids, linseed oil acids, coconut oil the carboxyl of the modifying agent reacts with acids, etc. Modification of this type improves the the hydroxyl of the glycolide chain, while the pliability of a film and enhances its durability. hydroxyl of the modifying agent reacts with the In achieving such a modification, it has been carboxyl of the glycolide chain. Other classes of found desirable to have the ratio of Carboxyl and bi-functional compounds may likewise be used, 50 hydroxyl units in the modifying ingredient or in the primary requisite being that the modifying gredients approximately one to one. - agent contains at least two reactive groups, one ad In a like manner, abietic acid (rosin) as a mod of which will react with the hydroxyl and the ifying agent, in addition to a phthalic-glyceride other with the carboxyl group of the glycolide in the preparation of a modified polyglycolide, chain. Examples of such compounds are: amino produces a resin particularly resistant to mois 2 2,862,511 ture, while addition of a long chain fatty alcohol was immediately and completely soluble in Hi or a cyclic alcohol, such as the terpene alcohols, flash naphtha (50-200 C.), acetone, isobutyl cyclohexanol and the like to a reaction mixture propionate, toluene and ethoxyethanol. The containing glycolic acid and a partially condensed resin exhibited good adhesion and was moderate tri-basic acid-dihydric alcohol prior to final con ly pliable. densation will decrease the water-sensitivity and While the examples do not illustrate the use increase the oil and hydrocarbon Solubility of the of a catalyst for accelerating the reaction be completely condensed resin. tWeen the modifying agent and the glycolic acid, The more detailed practice of the invention is a catalyst may be employed for speeding up this illustrated by the following examples, in which 10 reaction, and for this purpose such catalysts as parts given are by weight unless otherwise stated. litharge and p-toluene sulfonic acid may be em There are, of course, many forms of the inven ployed. Furthermore, it is advantageous in tion other than these specific embodiments. many instances to conduct the reaction in the Eacample 1-A mixture of 300 parts of glycolic presence of a Water-withdrawing agent such, acid dissolved in 233 parts of water and 17 parts 5 for example, as toluene, the halogenated hydro of lactic acid (85%) was heated rapidly to 200 carbons such as trichlorethylene and the like, C. in a closed vessel equipped with a mechanical for, by So doing, the water formed as a conse stirrer, thermometer, and condenser set for down quence of the reaction may be more readily with ward condensation, a slow stream of nitrogen drawn as formed or after the reaction has pro being passed over the reaction mixture to exclude 20 ceeded to the desired degree. air and aid in the removal of solvent water as The modified polyglycolide resins prepared in well as water of reaction. After 2.0 hours at 200 accord with the invention are particularly adapt C., the stirrer was removed and the viscous res ed for uses in the arts and they may be applied inous material heated an additional 0.5 hour in directly therein as plasticizers, extenders and the vacuo (15-20 mm. of mercury). The acid num 25 like for alkyd resins, phenol-formaldehyde and ber of the reaction product was 75. urea-formaldehyde resins; being employed in The resin was a tough, transparent solid of . place of polyvinyl acetate or in conjunction with low melting point (45-50 C.), soluble in di it for modification of the phenol-formaldehyde methyl formamide and was deposited on a glass resins. They are excellent adhesives for appli surface as a clear film. 30 cation either from hot melt or solution, the hot Eacample 2-A mixture of 122 parts of glycolic melt being particularly applicable for use with acid, 74 parts of phthalic anhydride, 48 parts of those modified polyglycolide resins which are glycerol (96%) and 122 parts of rosin was heat relatively insoluble. They may be used as ad ed rapidly to 240-250 C. and held between these hesives or binders, for plywood, for cementing temperature limits for 45 minutes, in a closed 35 rubber to artificial or natural fabrics such as vessel equipped with a mechanical stirrer, ther rayon, cotton, liner, hemp, and the like, for abra mometer, nitrogen inlet tube (through which sive wheels, sand and emery papers, for cork nitrogen was introduced during the reaction) compositions, for increasing adherence of latex and goose neck attached to a condenser set for or rubber to metal, for use in the preparation downward condensation. At the end of this of catalysts, for the preparation of cores in time, the reaction mixture was homogeneous and foundry practice and likewise in uses requiring was heated an additional 2 hours at 215-225 C., water-Sensitive adhesives. The modified resins in order to complete the condensation. The re may be dissolved in suitable solvents and used action product is a clear, amber-colored resin, alone or in conjunction with other lacquer con acid number 47. It was soluble in acetone, ethyl 45 stituents for coating wood, steel, concrete, or acetate, methoxyethanol, chloroform and diox other surfaces. They are useful as primers for ane, and forms a hard, tackfree film which was automobile finishes, as a component in tin deco particularly resistant to moisture.
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