2,940,949 United States Patent Office Patented June 14, 1960 2 tions having low brittle points. Other objects and their achievement in accordance with the invention will be 2,940,949 apparent hereinafter. COMPOSITION CONTAINING POLYPROPYLENE It has now been found that solid polymers of propyl AND AN ESTER PLASTCZER ene having improved properties can be prepared by com pounding polypropylene with a minor quantity of diesters Daniel R. Mullin, Chester, Pa., assignor to Sun Oil Com of adipic acid or diesters of polyethylene glycols. pany, Philadelphia, Pa., a corporation of New Jersey The crystalline polypropylene used in the process of No Drawing. Filed Aug. 26, 1957, Ser. No. 680,404 the invention is prepared by polymerizing propylene with a solid catalyst maintained as a dispersion in an inert, 9 Claims. (C. 260-314) liquid diluent, such as n-heptane or isooctane. The solid catalyst is preferably a halide of a metal such as zirconi um, chromium, vanadium, molybdenum or titanium This invention relates to new compositions of matter wherein the metal is in a valence state other than its and methods for their preparation. More particularly, 5 highest valence state. A lower halide of titanium such the present invention relates to solid polymers of propyl as titanium trichloride or titanium dichloride, or a mix ene compounded with certain additives to give new com ture thereof, is preferred. The metal halide is used with positions of enhanced properties. an activator therefor such as an aluminum alkyl. For Low molecular weight olefins such as propylene have example, aluminum triethyl, aluminum triisopropyl, heretofore been polymerized to relatively low molecular 20 aluminum tri-n-propyl, or aluminum triisobutyl are suit weight liquids or soft amorphous solids through the use able activators and give good results. Generally a mole of polymerization catalysts such as aluminum trichloride, ratio of activator to metal halide of 1:1 to 12:1 is used. boron trifluoride and the like. Such olefins can be poly Temperatures of from about 0° C. to 170° C. are suitable. merized to relatively high molecular weight solid polymers Atmospheric pressure can be used although elevated pres by contacting the olefin with a dispersion of titanium 25 sures are preferred in that the polymerization reaction trichloride and an activator such as aluminum triethyl proceeds at a faster rate at such elevated pressures, say maintained in an inert, liquid reaction medium. Gen up to about 10,000 p.s.i.g. (pounds per square inch gauge). erally such processes produce polymers of propylene Polypropylene is recovered from the reaction system by having molecular weights of above about 25,000 and draining the inert, liquid reaction medium and the catalyst usually within the range of from about 50,000 to 250,000. is deactivated and removed by contacting the polypropyl A proportion of the solid products obtained with pro ene with water, alcohol or an aqueous or alcoholic solu pylene using the mentioned catalyst appears crystalline, tion of an inorganic acid, such as nitric acid, with vigorous i.e., exhibits a crystalline structure by X-ray analysis. The agitation. Preferably such agitation provides for com crystalline polymer is relatively insoluble in the usual minuting the polymer, during the contacting with the hydrocarbon solvents, such as the paraffins including for catalyst deactivating liquid to insure good catalyst de example, the pentanes, hexanes, octanes, decanes, and the activation. ... The polymer is then repeatedly washed to like, even at elevated temperatures. However, the crystal remove at least a major proportion of the residual in line polymer can be dissolved in such solvents at relative organic material from the catalyst, and is then dried. ly high temperatures, as hereinafter described. This in The described procedure yields a product which is a solubility provides a means of separating crystalline poly 40 mixture of a predominate amount of crystalline polypro mers from amorphous polymers of propylene which are pylene with a minor amount of amorphous polypropyl also formed in the process, since the amorphous polymers ene. The amorphous polymer can be removed by dis are quite soluble in such hydrocarbons. Although the solution in a hydrocarbon solvent at an elevated tempera crystalline polymers of propylene, hereinafter for con ture below the temperature at which the crystalline poly venience designated "polypropylene,' possess many desir 45 mer is dissolved. For example, dissolution of the able properties, they are not suitable for use in many amorphous polymer in n-pentane at the boiling point of applications because of their high brittle points. By n-pentane (under atmospheric pressure), orn-heptane, iso "brittle point” is meant the temperature at which the octane, tetrahydronaphthalene, decahydronaphthalene, or polymer exhibits brittle failure under specific impact con the like gives good results. The resulting crystalline ditions as measured by ASTM test (D746-55T). For 50 polypropylene is then used in the process of the inven example, thin films or fibers of polypropylene are not tion. However, a quantity of the amorphous polymer, suitable for use in applications where flexibility is by which is meant the polymer which is soluble in n required, such as for use as wrapping materials, because pentane at the boiling point of n-pentane under atmos of cracking attemperatures encountered under usual room pheric pressure, say up to about 10% by weight, can be temperatures, or slightly below usual room temperatures. 55 present with the crystalline polymer and good results Likewise, polypropylene is not suitable for preparing fluid obtained. The crystalline polypropylene will generally containers, fluid conduits, or like articles for the same have a molecular weight of from about 25,000 to 300,000 eaSO. and usually from about 50,000 to 250,000, a melting Many plasticizers heretofore used with various plastic point of from about 161° C. to 171 C., and exhibits a materials do not appear suitable for improving the brittle 80 crystalline structure by X-ray analysis. The polypro point of polypropylene because such materials lower the pylene may be combined with a small quantity of oxygen, tensile strength and/or adversely affect other physical such as from oxidation by contacting air, and good results properties of the polymer, such as the melting point, melt obtained, even though such oxidation increases the brittle index, and the like. point of the polymer. Generally the quantity of oxygen An object of the present invention is to provide a poly 55 is below about 0.1%. In order to prevent excessive propylene composition having a low brittle point. An oxidation, it is advantageous to incorporate an oxidation other object is to provide a new composition of matter inhibitor in the polymer shortly after or during the prepa having a low brittle point comprising a relatively high ration. The presence of the inhibitor, in the quantities molecular weight polypropylene admixed with a minor required to Substantially completely prevent oxidation, quantity of a diester additive. A further object is to 0. does not adversely affect the compositions of the present provide a process for preparing polypropylene composi invention. - . . . . . 2,940,949. 3. 4 The additives of the present invention are diesters Example 3 -- selected from the group consisting of alkyl decyl adipates 10% by weight of di-ethylhexyl adipate was added to wherein the alkyl group has from 6 to 12 carbon atoms, the same inhibited polypropylene. The resulting com and diesters of polyethylene glycols wherein each acid position failed the brittle test, having a brittle point of portion of the diester has from 6 to 12 carbon atoms. above 4° C. The alkyl decyladipates of the invention are those which have the type formula ROOC(CH2)COOCoHai, where Example 4 in R may be any alkyl having from 6 to 12 carbon atoms. A composition was prepared using the polypropyl Examples of compounds of this type which will produce ene described above and 10% by weight of triethylene good results are di-isodecyl adipate, isodecyl-n-octyl glycol di(2-ethylhexoate). The brittle point was lowered adipate, n-octyl-n-decyl adipate, n-dodecyl-n-decyl adipate, to -7°C., the melt index was raised to .297 and the isohexyl-isodecyl adipate, and the isomers and homologues melting point was raised to 184 C. - thereof within the above limits. The diesters of poly ethylene glycols which may be used are those which Example 5 A similar polypropylene sample was combined with a have the type formula. - - polyethylene glycol di(2-ethylhexoate) having a boiling point at 5 mm. Hg of 255° C. The resulting composition - g - had a brittle point of -7°C., a melt index of .289, and R-C-O-CH3(CHOCH2)CH-O-C-R the melting point was raised to 197° C. wherein-R and R' are alkyl radicals having from 5 to 11 Many materials which have heretofore been described, as suitable for plasticizing polymers of other materials. carbon atoms; i.e., the acid portions of the diester have are not suitable for plasticizing polypropylene. Thus, for from 6 to 12 carbon atoms, and n is an integer greater example, compositions of polypropylene, with di-isohexyl than 1. Preferably the molecular weight of the diesters of adipate, phenyl ethylene oxide, benzoyl acetate, di-octyl polyethylene glycol is such that the boiling-point at 5. phthalate and tricFesyl-phosphate were prepared. With mm. Hg pressure is not greater than about 290 C. Some of these additives, namely di-octyl phthalate, and In order to prepare the compositions of the present in tricresyl phosphate, the resulting compositions not only vention; it is essential that the additive come within the failed in the brittle-test, but were brittle at room tempera above-defined groups. Similar compounds not within ture. Furthermore, such additives caused decomposition. the above definitions do not give operable results. For of the polymer, composition. None of these materials. example, diethylhexyl adipate and di-isohexyl adipate are gave a composition which passed the brittle point test. notFrom suitable-for-use about 7% to as 25% above by described. weight of the subject addi The invention claimed is: . . . tive: can be incorporated in polypropylene. When less 1. A new composition of matter comprising poly than the stated amount is used, the brittle point is not propylene and a material selected from the group con significantly affected, whereas large quantities adversely sisting of an alkyl decyl adipate wherein the alkyl group affect other properties such as the melt index. The com has from 6 to 12 carbon atoms and a diester of poly. positions are prepared by heating the polypropylene to a ethylene glycol having the type formula ...... temperature above its melting point, dissolving the addi - - 9 tive therein, mixing and cooling the resulting composition. 40 R-C-O-CH (CH,och)..CH-O--R If an oxidation inhibitor has not been incorporated into the polypropylene, the composition is advantageously. wherein RandR' are alkyl radicals having from 5 to 11 prepared under an inert atmosphere, such as an atmos carbon atoms and n is an integer greater than 1, and phere of nitrogen, to prevent oxidation of the polypropyl having a boiling point at 5 mm. Hg of not greater than 45 290° C. eC.The following examples illustrate compositions- 1 of the 2. A new composition of matter as defined by claim 1 invention and their preparation. In the examples, "parts' wherein the material selected is from about 7% to 25% refers to parts by weight. The polypropylene had a mo by weight of the composition. - leeular-weight of about 150,000, a brittle point of 4 C. 3. A new composition of matter as defined by claim 2 to 16°C., a melt index of about 0.1 and a melting point wherein the material selected is di-isodecyl adipate. of about 165 C. Prior to incorporating the additives, 4. A new composition of matter as defined by claim 2. about 0.2% by weight of an oxidation inhibitor, 4,4'-thio wherein the material selected is isodecyl-n-octyl adipate. bis(6-tertiary-butyl-m-cresol), was incorporated into the 5. A new composition of matter as defined by claim 2 polypropylene. The “brittle-point" as stated in the ex wherein the material selected is n-octyl-n-decyl adipate. amples was determined by ASTM method D746-55T. 6. A new composition of matter as defined by claim 2 Compositions having a brittle point of about -4° C. are wherein the material selected is triethylene, glycol di(2- considered-to fail in the test. By "melt index,” as used. ethylhexoate). herein, is meant the weight of polymer expressed in grams. 7. A new composition of matter as defined by claim 2 extruded through an orifice: 0.0823 inch in diameter from wherein the material selected is polyethylene glycol di(2. a barrel 0.3760-inch in diameter under the force of a 60 ethyl hexoate) having a molecular weight such that its piston weighing 2160 grams, the polymer being main boiling point at 5 mm. Hg is from 215° C. to 290° C. 8. A new composition of matter consisting essentially tained at 190° C. during the extrusion. of predominantly crystalline polypropylene, an oxidation Example: I - inhibitor, and a material selected from the group consist 10% by weight di-isodecyl adipate was incorporated 65 ing of an alkyl decyl adipate wherein the alkyl group into the above polypropylene. The resulting composition has from 6 to 12 carbon atoms, and a diester of poly had a brittle point of -18° C., a melt index of 0.505, ethylene glycol having the type formula . and a melting point of 185 C. - - - - Example 2 70 R-6-O-CH;(CHOCH) CH-O-6-R ... 10% by weight of isodecyloctyl adipate was combined wherein R and R' are: alkyl radicals having from 5 to 11 with the same inhibited polypropylene, resulting in a com carbon atoms and n is an integer greater than 1, and position having a brittle point of -20 C., a melt index having-a-boiling point at 5 mm Hg of not greater than of 0.42, and a melting point of 169 C. 290° C...... 2,940,949 S. 9. A new composition of matter as defined by claim 8 2,274,672 Dennison ------Mar. 3, 1942 wherein the oxidation inhibitor is 4,4'-thio-bis(6-tertiary- 2,670,382 Downey et al. ------Feb. 23, 1954 butyl-n-cresol). OTHER REFERENCES References Cited in the file of this patent 5 y: 5: Eger." Cleaver-Hume Press Ltd., New UNITED STATES PATENTS Natia: jórial of Polymer Science, volume XVI, pages 2,244,021 Rosen et al. ------June 3, 1941 143-154, 1955.