US2957225A - Fiber of poly - Google Patents

Description

United States Patent FIBER OF POLY(4-METHYL-1-PENTENE) Frank J. Welch, South Charleston, and Frederick P. Reding and Andrew T. Walter, Charleston, W. Va., assignors to Union Carbide Corporation, a corporation of New York No Drawing. Filed May 4, 1956, Ser. No. 582,632

'3 Claims. (CI. 2882) The present invention relates to novel polymeric fibers and methods of making the same. More particularly it relates to poly(4-methyl-1-pentene) fibers, and methods employed in the preparation thereof.

According to heretofore customary procedures it was known to polymerize olefins such as ethylene, isobutylene and styrene or its homologues to high molecular weight solid homopolymers. However, we have found that fibers made from poly(4-methyl-1-pentene) are superior in melting point, extensibility and tensile strength to such homopolymers. Further, the present invention also includes processes for preparing fibers from poly(4-methyll-pentene), and particularly high molecular weight fibers of a high degree of crystallinity.

Accordingly, in the present invention it has been found that filamentary material may be prepared from 4-methyl-l-pentene homopolymer having a melt index of 0.1 to 40 by extruding the said polymer through a spinneret at a temperature from about 260 C. to 350 C. to form a continuous fiber. This extruded product is then stretched to two to eight times its length at a temperature of 50 C. to 220 C.

The stretched-oriented fibers prepared from poly(4- methyl-l-pentene) by the process of the present invention have an ultimate elongation at break of at least 15 percent and up to approximately 30 percent and a tensile strength at break of at least 1.5 grams per denier. In its preferred embodiment, however, these fibers have an ultimate elongation at break of about 18 percent and a. tensile strength of 6 g.p.d. Illustratively, a sample of poly(4-methyl-l-pentene), in granular or flaked form, is charged to a suitable melting device such as, for example, a melt grid or extruder and fed in the molten conditions to a metering pump. The polymer that is discharged at a constant rate from the metering pump is forced through a suitable filtering medium, such as a sand-pack, and thence through a spinning die having one or more (up to about 250) orifices. The molten polymer filaments which are formed in this manner are then extenuated while still in the molten state to reduce their diameter and are then rapidly cooled in a stream of air or cool fluid medium and wound onto a bobbin to form a suitable yarn package. The spun yarn is then stretched and oriented to improve its properties in the following manner: The spun yarn is withdrawn from the package and passed around an advancing roll (godet) to control the rate of feed to the stretching zone. The yarn is stretched while passing through a heated zone by a second godet rotating with a higher surface speed than the first godet. The yarn may be heated by radiation or by contact with a surface or a hot fiuid medium of suitable temperature (i.e., 50 C. to 220 C.). The stretched yarn is then rewound onto a suitable bobbin for subsequent textile operations. The operative limits for conducting the preparation of poly(4-methy1-1-pentene) fibers are as indicated in Table I.

TABLE I Limits for the spinning process Polymeric fibers made in accordance with the present invention having a high melting point, a considerable degree of crystallinity (i.e., at least 50 percent, with a preferred range extending from about percent to about percent for the purified polymer), and a high degree of toughness and strength are of particular value for use in textile yarns.

The crystalline polymers preferably employed in forming the fibers of the present invention are obtained from the reaction product containing a mixture of amorphous and crystalline poly(4-methyl-1-pentene) by forming the polymer in a suitable solvent (i.e., aromatic and saturated aliphatic hydrocarbons such as hexane, heptane, benzene and the like) or placing it therein, wherein the amorphous polymer is dissolved and the crystalline portion, being insoluble, is separated out.

Poly(4-methyl'-l-pentene) is prepared by polymerizing 4-methyl-1-pentene in the presence of a catalyst composition composed of a halide (i.e., bromide, fluoride or chloride) of a metal such as, preferably, for example,

titanium, vanadium or tungsten, and a compound of the formula RAlR wherein A1 is aluminum; R is an alkyl group containing at least one carbon atom or hydrogen; and each of R and R is an alkyl group containing at least one carbon atom; and aninert diluent (i.e., a hydrocarbon solvent) to form poly(4-methyl-1-pentene).

The resultant product polymer, poly(4-methyl-l-pentene), is a tough, clear, highly crystalline resin, having a melting point of about 235 C. and a high stiffness measured at room temperature of 150,000 pounds per square inch, as is seen also in Table II below. The polymer has a melt index of approximately 0 at 250 C. and a density of 0.831 gram per cubic centimeter at 25 C The stiffness of the resin at several different temperatures was measured by an Instron tester made by the Instron Engineering Company of Quincy, Massachusetts (Model 37-), at a rate of strain of 10 percent per minute, a force one hundred times that required to stretch the polymer one percent, and the results are as follows:

TABLE II Stiffness, pounds per square inch (p.s.i.)

P01y(4-metl1yl-1-pentene) 150,000 23,000 11,000 7 4.500 700 It is also of interest to note that the resin is essentially crystal clear even though it is highly crystalline, an indication that spherulitic structures are either not formed at all, or are very small. This clarity is, for example,

much greater than that found in polyethylene, a material in a %-inch-diameter tube at 250 C. and a load of 2160.

grams is applied to a plunger which forces the melted polymer through a die having a diameter of 0.0825 inch. The melt index of the polymer sample is the rate, in decigrams per minute, at which the polymer is extruded under these conditions. By wayof illustration, polymers of high molecular weight extrude :more slowly and therefore have a lower melt index.

The. polymerizations described herein are conducted in the presence of an inert. diluent which, is selected from the saturated aliphatic, saturated cycloaliphatic and aromatic hydrocarbons and while serving as a solvent for the monomer, need not necessarily function .as such for either the polymer or the catalyst. The diluent, however, must not contain highly polar substituents, (i.e., nitriles and the like) oxygen, sulfur, active hydrogen, (i.e., alcohols, water, certain amines) or olefinic unsaturation which react with the catalyst and consequently inactivate it. Suitable hydrocarbon solvents are, for example, toluene, benzene, xylene, methylcyclohexane, cyclohexane, hexane, heptane, and highly purified'kerosene. Heptane is a preferred diluent.

The catalyst employed herein is composed of two components which may or may not react chemically with each other in the reaction mix. The first component is an organometallic compound such as trialkylalumium (triisobutyl aluminum and trioctyl aluminum) wherein the alkyl substituents contain at least one carbon atom and preferably from 2 to 12 carbon atoms. The preferred trialkylaluminum is triiosbutyl aluminum. The second component is a metallic halide such as'titanium tetrachloride, titanium trichloride, titanium dichloride, vanadium tetrachloride, vanadium trichloride, vanadium dichloride, zirconium tetrachloride, titanium tetrafluoride, titanium trifiuoride, titanium tetrabromide, and titanium tribromide. Titanium trichloride is most advantageously employed in this regard. Halides of other metals in Groups IV-B, V-B, or VIB or the Periodic System of the Elements, for example, zirconium, hafnium, niobium, tantalum, chromium or molybdenum, could be used in place of the titanium trichloride or other metallic halide.

The molecular ratio of the trialkylaluminum to titanium trichloride used to make the catalyst can vary from 0.5 up to 12 or more. The ratio employed is not narrowly critical and may be varied considerably, without adversely affecting the reaction. Thus, the polymerization works as well at higher ratios while the preferred ratio for efiicient and economic operation is l to 5.

However, the preferred molecular ratio of the trialkylaluminum to titanium tetrachloride or the ratio of equivalent amounts of other materials as listed hereinabove is somewhat more clearly delineated. Thus, a ratio range of from 0.5 to 12 is operable whereas a range of 0.5 to 4 is preferred. At higher ratios the conver-- sions are substantially decreased.

The total catalyst concentration in the reaction mix is not critical. The upper limit for catalyst concentration is an economic one, although excess concentrations do tend to lower the molecular weight, while concentrations as low as one millimol of titanium trichloride per liter of diluent, for example, are wholly operative and may be further decreased.

The techniques, used .in combining the catalyst, diluent,

and monomer are well known procedures designed to exclude moisture. It has been found, for example, that the addition of trialkylaluminum, or like compound as described hereinabove, .to the diluent first and the subsequent addition of titanium trichloride leads to higher polymer/catalyst ratios; however, the reactants may be added in reverse order. This higher ratio would appear due to the scavenger effect of the alkyl and since it is used generally in larger quantities, a small loss of it is preferred rather than a loss of trichloride. It has been found that by adding monomer continuously as the reaction proceeds and thus avoiding a high initial concentration thereof, higher density polymer is obtained. The monomer is added as a liquid and the vessel sealed. The reaction mix is stirred at the ,desired temperature and polymerization takes place under autogenous pressure.

If desired, polymerization may be conducted at atmospheric pressure in agitator equipped vessels. In such case, air and moisture are excluded by maintaining an inert (e.g., nitrogen) atmosphere. The rate of polymerization is slower at atmospheric pressure.

The temperature of polymerization has a marked effect on the molecular weight of the polymer. In general, the higher the'temperature,,the lower is the molecular weight. Temperatures ranging from 0 C. to 170 C. operative when employing titanium trichloride .as the cocatalyst, although temperatures from about 25 C. to about 150 C. are most advantageously employed. Yields of polymer are very low at temperatures in excess of 170 C. At temperatures below 25 C., the polymerization rate falls to low values. The polymerization at 50 C. proceeds very well in 4 to 8 hours to give conversions of 85 percent. It all the monomer is charged initially, about 20 percent of the polymer is soluble in hydrocarbons (amorphous fraction). By feeding the monomer slowly as the polymerization proceeds and thus avoiding a large initial concentration of monorner, the

; insoluble fraction can be increased to 9095 percent.

V polymer are obtained. About 50 to 60 percent of the At 25 C., the polymerization proceeds more slowly than at 50 C.

When titanium trichloride is used with triisobutylaluminum and Without avoiding a large initial concen tration of monomer, higher proportions of crystalline polymer is obtained in crystalline form employing titanium tetrachloride to percent for an equivalent amount of titanium trichloride. The remainder is amorphous polymer. For this reason as Well as the fact that the tetrachloride is not so effective at higher temperatures (i.e., C. to C.) with the monomer, titanium trichloride is preferred.

Crystallinity is determined by placing the product polymer in hexane, wherein the amorphous polymer is dissolved and the insoluble fraction separated therefrom. This insoluble portion is molded into plaques and X-ray difraction tests run thereon. These tests indicate that this insoluble portion which is employed in fiber-forming operation is about 100 percent Crystallinity. The ratio of crystalline polymer formed in relation to the amount of amorphous polymer formed, is determined by recovery of the amorphous polymer from the hexane solvent by evaporation of the latter.

When the polymerization reaction is complete, the contents of the reaction vessel are mixed with iopro'panol, methanol or water containing up to 10 percent hydrochloric acid to solubilize the catalyst residue. The polymer is removed by filtration, washed again and dried. The amorphous material can be separated by extracting with any suitable solvent such as, for example, toluene, heptane, hexane, kerosene and diethylether, at room tem perature. The crystalline polymer is insoluble at room temperature and can be recovered by filtration. The amorphous material can be precipitated from the solvent using, for example, methanol or isopropyl alcohol.

Examples 1 to -9 inclusive demonstrate the production of 4-methyl-l-pentene homopolymers. Examples 10 and 11 describe the formation of polymeric fibers from the said homopolymer, and while illustrative of the invention, are not to be construed in limiting the scope thereof.

EXAMPLE 1 A mixture of 400 milliliters (mL) hexane, 60 grams (g.) 4-methyl-l-pentene, 8 g. triisobutylaluminum and 3.8 g. titanium tetrachloride was divided and charged to two Pyrex bottles. The bottles were capped and placed in a rotating basket in a 40 C. water bath. After 18 hours the bottles were removed and opened. A precipitate had formed which was filtered ofi, washed with isopropyl alcohol and dried. It weighed 18 g. The melt index of the solid was 0, and its density was 0.830. The filtrate of the reaction'mixture was diluted with isopropanol, causing a precipitate to form. This was washed with alcohol and dried. The dry material weighed 9 g. Its melt index was and its density was 0.830.

EXAMPLE 2 A mixture of 200 ml. hexane, 30 g. 4-methyl-l-pentene, 4 g. triisobutylaluminum and 1.9 g. titanium tetrachloride was polymerized in a capped Pyrex bottle at 40 C. for 6 /2 hours. The product was worked up in the same fashion as in Example 1. The soluble fraction weighed g., the insoluble fraction 7 g.

EXAMPLE 3 The charge and procedure of Example 1 was repeated, but the polymerization was carried out at 60 C. for 17 hours. The polymer (insoluble fraction) weighed 23 g., its melt index was zero, and its density was 0.830.

EXAMPLE 4 A clean, dry Pyrex bottle was flushed with nitrogen and was charged with the following materials in a dry box:

200 ml. of hexane 0.49 g. of TlC13 2.0 g. of triisobutylaluminum (Al/Ti=3.2) 50 g. of 4-methyl-1-pentene The bottle was capped and placed in a rotating water bath at 50 C. for 17 hours. The resultant polymer mixture was then diluted with hexane and filtered. The insoluble polymer was washed with isopropanol and water to remove the catalyst residue and after drying, 34 g. of polymer was obtained. The filtrate was mixed with isopropanol whereupon 8 g. of amorphous polymer precipitated. The total conversion was 84 percent and the conversion to crystalline polymer was 68 percent. The melt index of the insoluble fraction was 0.00.

EXAMPLE 5 A clean, dry Pyrex bottle was flushed with nitrogen and was charged with the following materials:

200 ml. of hexane 1.05 g. of TiCl 2.0 g. of triisobutylaluminum (Al/Ti=2.0) 50 g. of 4-methyl-1-pentene The bottle was capped and placed in a rotating water bath at 50 C. for 85 hours. The polymer was washed with isopropanol and with water and hydrochloric acid to remove the catalyst residue. The dry polymer weighed 20 g. (40 percent conversion).

EXAMPLE 6 The same charge and conditions were used as in Example 5 except that the time of reaction was 16 hours. The polymer was separated into insolubleand solublein-heptane fractions. A total yield of 36 g. represented a 72 percent conversion of which 20 g. or 40 percent was insoluble polymer and 16 g. or 32 percent was soluble.

The yield of crystalline material was identical with that in Example 5. The molecular weight of this polymer was higher than that in Example 5 where the amorphous polymer was lost during washing.

The melt index of this sample was 0.04 and the flow rate was 1.1 measured at 250 C.

EXAMPLE 7 A two-liter resin flask equipped with a stirrer, reflux condenser, thermocouple well, and a combination nitrogen inlet and dropping-funnel inlet was charged as follows:

400 ml. Bayol-D (scrubbed kerosene) 1.0 -g. TiCl 4.4 g. triisobutylaluminum (Al/Ti=4) 60 g. of 4-methyl-1-pentene The 4-methyl-1-pentene was added after a temperature of C. was obtained, whereupon the temperature fell to 100 C. Over a period of 19 hours, the temperature slowly increased to C. as the free olefin disappeared. The polymer was washed with isopropanol and water and upon drying, weighed 15 g. for a 25 percent conversion. A melt index of 0.26 and flow rate of 21.4 was obtained indicating that at higher temperatures a lower molecular Weight is obtained (compared with melt index of 0.00 obtained in Example 4 at 50 C.).

EXAMPLE 8 The following charges along with 50 g. of 4-methyl-' l-pentene were placed in six separate bottles and were reacted for six hours at 50 C. The techniques of ham dling were the same as in Example .4.- The polymer obtained was about 60 percent insoluble in heptane in all cases.

TiOls, Triisobutyl- Al/Ti Hexane, Poly(4methylaluminum, g. ml. l-pentene), g.

EXAMPLE 9 A clean, dry Pyrex bottle was flushed with nitrogen and was charged with the following materials:

200 ml. of hexane 0.96 g. of TiBr 1.04 g. of triisobutylaluminum 40 g. of 4-methyl-1-pentene The mixture was placed in a rotating water bath at 50 C. for 17 hours. The polymer was washed with isopropanol and with water containing hydrochloric acid to remove the catalyst residues. The polymer was white and powder-like and weighed 9 grams.

EXAMPLE 10 A sample of poly(4-methyl-l-pentene) prepared as described in Example 5 was melt spun and hand-drawn to a 22-denier monofilament. The polymer was prepared at 50 C. in hexane with a titanium tetrachloridetriisobutylaluminum catalyst, and was evaluated without fractionation or separation of any amorphous polymer that might have been present. The polymer had a melt index of 41 measured at 250 C., a density of about 0.83 and a melting point of about 240 C.

The polymer was charged to the experimental plungerextruder, heated to 270 C., and extruded through a 0.047-inch diameter orifice at about 3 feet per minute and a hot-draw ratio of about 10 to l. The spun filament could be stretched by hand from 300 percent to 400 percent over the surface of a metal pin heated to 55 C. The tenacity and elongation of the handstretched filament was 2.3 grams per denier (g.p.d.) and 21 percent, respectively, and the stifiness modulus was very high-85 -g.p.d. Good temperature resistance was a very important feature of this stretched-fiber as indicated by the low shrinkage in boiling water percent) and in 200 C. ai-r (9.5 percent).

EXAMPLE 11 Poly(4-methyl-1-pentene) prepared in accordance with Example 6 was charged to the experimental plungerextruder heated to 27029,0 C. and extruded through a, 0.020 inch diameter orifice at about 15 feet per minute. The spun filament was stretched 200 percent over the surface of a metal pin heated to 200 C. The tenacity of the drawn filament was 2.2 to 4.5 g.-pd. with an elongation of 26 to 32 percent. The measured stiffness modulus was 22 to 31 g.p .d. The measured stifiness modulus of 22 to 31 g.p.d. was determined on an Instron Tester (Model T .M'., manufactured by Instron Engineering Corporation). The stretched fiber was subjected to a consistent rate of elongation and that rate in elongation is equal to 50 percent of the initial length of the specimen (l-inch sample) per minute. The stifiness modulus is determined on this curve, so obtained above, at a point that represents a stress of one percent elongation. The value thus .obtained is multiplied by 100 to yield the stifiness modulus as indicated above.

What is claimed is:

1. A stretched-oriented fiber formed from poly(4- methyl-l-pentene) having a erystallinity of at least 50 percent, said fiber being characterized by an ultimate elongation at break of at least 15 percent, a melting point of about 235 C. to about 240 C., and a tensile strength of at least 1.5 g.p.d.

2. A stretched-oriented fiber formed from purified poly(4-methyl-1-pentene) freed from amorphous polymer and having a crystallinity of at least percent, said fiber being characterized by an ultimate elongation at break of 15 percent to 30 percent, a melting point of about 235 C. to about 240 C., and a tensile strength of at least 1.5 g.p.d.

3. A stretched-oriented fiber formed from purified poly(4-methyl-1-pentene) freed from amorphous polymer and having a crystallinity of about percent, said fiber being characterized by an ultimate elongation at break of 15 percent to 30 percent, a melting point of about 235 C. to about 240 C., and a tensile strength of at least 1.5 'g.p.d.

References Cited in the file of this patent UNITED STATES PATENTS 2,170,439 Wiezevich Aug. 22, 1939 2,210,774 Perrin et a1. Aug. 6, 1940 2,352,328 Kleine June 27, 1944 2,605,509 Dreisbach Aug. 5, 1952 2,612,679 Ladisch Oct. 7, 1952 2,674,025 Ladisch Apr. 6, 1954 2,681,903 Linsk June 22, 1954 2,712,490 Stuchlik July '5, 1955 2,820,778 Spaenig et a1. Jan. 21, 1958 2,825,721 Hogan et a1. Mar. 4, 1958 Disclaimer 2,957,225. Fmn7c J. Weloh, South Charleston, Fredem'ck P. Healing and Andrew T. Waltew, Charleston, WV. Va

. FIBER OF POLY(4-1W:ETHYL1 PENTENE). Pa tent dated Oct. 25 1960. Digclairner filed Aug. 28,

'mer to claim 1 of said patent. [Ofioial Gazette 00270661" 16, 1962.]

Claims (1)

1. A STRECHED-ORIENTED FIBER FORMED FROM POLY(4METHYL-1-PENTENE) HAVING A CRYSTALLINITY OF AT LEAST 50 PERCENT, SAID FIBER BEING CHARACTERIZED BY AN ULTIMATE ELONGATION AT BREAK OF AT LEAST 15 PERCENT, A MELTING POINT OF ABOUT 235*C. TO ABOUT 240*C., AND A TENSILE STRENGTH OF AT LEAST 1.5 G.P.D.