CA1207483A - Thermoplastic elastomers - Google Patents

Abstract

THERMOPLASTIC ELASTOMER

Abstract Thermoplastic elastomeric sequentially prepared propylene and (ethylene-propylene) polymer, or propylene, (ethylene-propylene) and propylene polymer, made in solvent medium with catalyst system based on (a) complex of titanium tetrachloride and alkyl benzoate or a phenol, supported on magnesium dihalide and (b) trialkyl alumi-num modified by electron rich substituted benzoate.

Description

~7~3 THERMOPLASTIC ELASTOMER --This invention relates to a thermoplastic elastomer and a me-thod of making same.
More particularly the invention relates to a thermoplastic elastomer which is a sequentially prepared propylene and (ethylene-propylene) polymer, or a sequentially prepared propylene, (ethy-lene-propylene) and propylene polymer. In one aspect, the inven-tion is directed to such a thermoplastic elastomeric sequentially prepared polymer having ~A) polypropylene segments showing crystallinity of the isotactic polypropylene type, and (B) amorphous segments which are elastic ethylene-propylene materials, said seg-ments (A) and (B) being only partially block copolymerizecl to each other, the weight ratio of (A) to (B~ segments being within the range of from 10:90 to 75:25 and the product being characterized by lamellar chain-folded crystallinity at room temperature, as evi denced by at least one differential thermal anal~rsis ("DTA") melting point of at least 150C. The product is believed to comprise two interpenetrating networks ~two intertwined continuous phases) one of which is plastic in na~ure ~essentially polypropylene) and the other rubbery in nature (essentially ethylene-propylene polymer).
It is known that in order to introduce true rubber character-istics (elasticit~) to an amorphous polymeric material which is above its second order transition temperature (glass transition tempera-ture, "Tg") at room ~mperature, one has to introduce "anchoring points" which ~ie the polymeric chains into giant macromolecules.
When this is done by forming chemical bonds which link all the chains together, one talks ab~ut "curing" or "crosslinking" the rubber. However, chemically crosslinking the rubber alters the rubber to a point where i~ can no longer be reprocessed (it is no longer thermoplas tic) and any scrap material has to be discarded .
By using physical "crosslinks" (such as anchoring points based on high glass transition temperature, crystallinity, or ionic bonds) in place of true chemical crosslinks, one can undo the crosslinking effect by simply raising ~he temperature to a point which ov~ercomes ~`.~

~Z~4~33

2-the anchoring of chains and allows random motion. Cooling rean-chors the chains. Any scrap can thus be reused. These types of rubbers are called thermoplastic elastomers.
One known kind of thermoplastic elastomer is a blend of poly-5 olefin plastic (e . g . polypropylene) and olefin copolymer rubber(e . g ., EPM; ethylene-propylene rubber~, known as "TPO" . The thermoplastic elastomeric properties of TPOIs are thought to come about from interpenetrating networks of a continuous plastic (poly-propylene) phase and a continuous rubber (EPM) phase. The 10 "crosslinking" in such polymers may be regarded as provided by "hard segments " interweaving throu~h a continuous matrix of "soft material". There is thought to be enough interaction (Van der Waals forces) along the continuous interfaces to allow the hard segments to act as anchoring points at moderate temperatures and 15 thus provide elastic behavior. At high temperatures ( 125~C) the interac~ions are weakened and the stress-strain properties deter-iorate rapidly. At even higher processing temperatures ( 160C) the anchoring points melt and thereby lose their risidity, i.e., the material becomes thermoplastic. This allows the shaping of the 20 blends into final form.
The TPO's exhibit electron micrographs at 8,000 to 20,000 magnification level consistent withl interpenetrating networks;--do-mains of plastic particles in a "sea" of rubber for high rubber-low - plastic content materials, to the other end of the spectrum of ru~-25 ber domains in a "sea" of plastic for the low rubber-high plastic content materials. It has been shown by scanning electron micros-copy of a hexane-extracted film of TPO that the undissolved poly-propylene was present in a continuous network throughout the film.
Following the holes created in the material as shown by the scan-30 ning electron micrograph, one can see that the EPM ru~ber phase was also continuous. The polypropylene phase has been shown to be isotactic polypropylene with a melting point in the range of 160-175C. The crystallites are of the chain-folded lamellae type.
Certain TPO's have some chemical crosslinking, introduced by 35 partially curing with a peroxide or other curative while dynamically working the mixture, to enhance the properties without destroying thermoplasticity. The advantages of this are lower compression set, L,.......................................... - -ot7~

higher tensile at high temperatures, and better tensile to hardness ratio. The transmission electron micrographs of these dynamically partially crosslinked TPO's are different in that the two phases are better dispersed in one another and there are no smooth interfaces 5 but rather many jagged edges delineate the boundary areas.
One object of the invention is to avoid the expensive and energy intensive mixing step necessary in preparing conventional blended types of TPQ's. Another object is to provide a thermo-plastic elastomer having good properties without any necessity for a 10 dynamic partial curing step.
U . S . patents 3, 378, 606 and 3, 853, 969 issued to Emmanuel G .
Kontos on April 16, 1968 and Dec. 10, 1974, respectively, disclose semicrystalline or crystallizable block copolymers. The materials of Kontos are true (substantially complete) block copolymers as evi-15 denced by the fact that the materials are soluble in boiling heptane,whereas the present products contain considerable (e . g . 30-70% by weight) heptane insoluble material. It is believed that properties of the Kontos products do not arise from interpenetrating networks but rather from domains in a sea of rubber . The r i~id domains 20 appear to act as anchor points for the rubbery chain segments; the rubbery chains are apparently chemically bonded to the rigid do-mains. Production of the Kontos materials is difficult bPcause of low polymer yields, high solution viscosities and relatively long reaction t~mes. Kontos employs a "living'l catalyst, with the result 25 that added monomer units continually add on to living ends of the polymer molecule existing in the reaction mixture, thus making a very high molecular weight polymer and producin~ a highly viscous reaction mass. The present process, in contrast, provides for formation of at least some of a short-lived polypropylene species 30 which do not have a "livin~" end and therefore do not continue to grow by attachment to monomer added during the process. This provides the important crystalline polypropylene phase that is characteristic of the present product.
Similarly, V.S. patent 3,970,719, Edmonds, Jr., July 20, 1976, 35 discloses a sequential polymer of polypropylene and (ethylene-propy-lene) made with living catalyst and containing no substan~ial sepa-rate polypropylene resin phase as in the present product.

The preparation of thermoplastic elastomers by direct polymer-ization OI ethylene and propylene is disclosed in United States patent 4,293,721, Borghi et al, Nov. 3, 1981. The products unfor-tunately contain polypropylene crystallites having a DTA melting point of only 100 to 130C; molding shrinka~e is high. The indi-cations are that the product has a kind of crystallinity known as fringed micellar type, rather than the chain folded lamellar type characteristic of the product of the present invention. The present products maintain good properties at elevated temperatures whereas the lower melting points of the Borghi et al. products limits their usefulness to temperatures below 80S~.
U . S . patent 4,107,414, Giannini et al ., Aug . 15 , 1978, dis-closes making prevailingly isotactic polymers (i . e . crystalline ma-terials with little or no amorphous component) from propylene and higher alpha-olefins, using a catalys$ which is useful in the present invention. Alsu disclosed is the polymerization of propylene in the presence of small amounts of ethylene fed continuously or intermit-tently after a conversion of propylene into polypropylene of at least 80% is reached. In the present elastomeric products, in contrast, not more than 70% (typically much less) of total polymerized pro-pylene is represented by the crystalline segment.
In accordance with the preserlt invention, reactor-produced thermoplastic polyolefins are prepared by sequential polymerization of propylene and (ethylene-propylene) or propylene, (ethylene-pro-pylene), and propylene using supported complexed titanium cata-Iysts with modified ~rgano alum num cocatalysts. In general the catalyst system employed may be characterized as a catalyst based on titanium halide (or complex thereof with an electron donor) supported on a carrier such as a magnesium or manganese halide, and a cocatalyst which is an organo aluminum compound such as an alkyl aluminum, particularly a substitution or addition product of a trialkyl aluminum with an electron donor. The polymers produced are characterized by a total propylene content of from 60 to 95% by weight; a ratio of absorption intensity, in the infrared spectra, between the band at 11.88 microns and the band at 12.18 microns of more than 7.0; in the Raman spectra, a ratio of the intensity of the band at 810 cm 1 and the ~and at 840 cm 1 of more than 1.0 and a ratio of the intensity of the band at 2880 cm 1 to the band at 2850 cm 1 of more than 2.0; at least one differential thermal analysis melting point of at least 150C; a flexural modulus, at room tem-perature, of less than 100,000 psi; an elongatioll, at room tempera-ture, of more than 150%.
The polymers produced are further characterized by melting points of 150 to 156C ~or some of the segments; useful rubbery properties somewhat below these melting points and down to at least -30C; and processability in equipment used Eor thermoplastic materials above the melting points referred to above.
We have now found, in accordance with the invention, that carrying out the polymerization in stages so as to polymerize only propylene in the first phase and ethylene and propylene in the second stage leads to materials with high melting p~ints (150-166~C
determined by DTA; see B.Ke, "Newer Methods of Polymer Charac-terization, " 1964, Interscience Publishers, chapter 14) and good tensiles for a given hardness value (Shore A). The present new polymers tend to retain some of their useful properties even at the high temperatures oE 250F ( 120C~.
A tri-step polymerization where propylene is polymerized in the first step and ethylene and propylene in the second step followed by propylene polymerization in the third step, gives rise to similar polymers with possibly slightly lower Tg values and higher tensile values .
It is believed that in the process of the invention propylene is initially polymerized to yield at least twc different polypropylene species, one species being a living polypropylene polymer capable of continuing addition of other monomer units to its living end, while an other species has a relatively shorter lived end that dies oEf leaving polypropylene that will not grow more. Therefore at the end of the first polymerization sequence the reaction mixture is thought to contain non-living polypropylene (resin~ and living polypropylene. When ethylene is added in the next polymerization sequence ~ it is believed that the polymerization can take several routes, including addltion of ethylene and propylene onto the living polypropylene from the first step. It is thought that at the end of the second sequence the species present can include PP, EP, P-EP, living EP and living P-EP. At this stage the polymerization can be ended, or the process can proceed to a third sequence involvin~
addition of more propylene monomer~ After addition of further 5 propylene, the polymerization can continue with more variations.
Thus, the living EP and living P-EP can add on propylene and more polypropylene can be formed. It is thought possible that the final mixture, after quenching the living polymer, can include such species as PP, EP, P-EP, EP-P, and P-EP-P. While it is not de-10 sired to limit the invention to any particular theory of operation, itis believed to be possible that the unique nature of the present product is a consequence of the ability of the catalyst system employed to form not only polypropylene with living ends having a relatively long life as in such prior art as Kontos, but also poly-15 propylene with ~hort lived ends with the result that a resinouspolypropylene phase is formed in addition to the rubber phase. In the present product, from 10 to 70% of the total polymerized pro-pylene is in a crystalline, isotactic (resinous) form.
It is not immediately evident that the present "P/EP" and "P/EP/P" type polymers would be so useful. Many polypropylene catalyst systems will incorporate ethylene to some extent so that the preparation of some kind of P/EP/P and P/EP type polymer is made possible. What is especially novel is that P/F.P and P/EP/P poly-mers of the invention have such good physical properties without 25 undergoing an intensiYe mixing step, and without dynamic partial curing. In nearly all other cases, polymers produced with the other propylene catalyst systems have very poor physical proper-ties .
In these latter cases, there is apparently not enough inter-30 facial interaction between phases or enough dispersion of the twophases (or a combination of both~ to ~ive the required stress-strain properties. An example of such a catalyst system is ~he well known alkyl aluminum halide - TiCl3~A catalys~ system.
Conversely in the present case where one uses a supported-35 complexed titanium catalyst one surprisingly gets enough dispersionof the polypropylene to give the desired stress-strain properties.

~L~7 The present P/EP/P polymerization is a method of making product in which monomers are introduced to max~m~æe the polymer-ization to P/EP/P. The product is not exclusively a true tri-block polymer. In reality, as indicated, all the possible combinations 5 such as polypropylene, propylene-EP block, EP-propylene block, ethylene-propylene copolymer, and propylene, ethylene-propylene, propylene tri-block polymer are apparently present. A similar si~uation appears to exist with the P/EP polymer. In any event, the catalyst species present, the polymerization rates, the sequen-10 tial polymerization, and the workup, all combine to give mixtureswhich possess the properties needed to be of commersial interest.
The thermoplastic elastomers of the present invention contain from 60 to 95% by weight of propylene and show crystallinity of the isotactic propylene type. The crystallinity values are in the range 15 of 15 to 45% as measured by X-ray. The polypropylene segments comprise 15-70% by weight of the total polymerized propylene. The intrinsic viscosity of the polymers ~measured in tetralin at 135C) is between 1.5 and 6 or even higher and the tensile values are depen-dent not only on propylene content but also on the molecular weight 20 as reflected in the intrinsic viscosity value. The flexural modulus and elongation, at room temperature are less than 100, 000 pounds per square inch and more than 150SL, respectively.
Uniquely, the thermoplastic elastomers of this invention are characterized by spestral proper$ies that include, in the infrared 25 spectrum, a ratio of absorption intensity between the band at 11.88 microns to the band at 12 .18 microns of more than 7 . 0; m the Raman specrum, a ratio of the intensity of the band at 810 cm 1 to the band at 840 cm 1 of more than 1.0, and a ratio of the intensity of the band at 2880 om 1 ts the band at 2850 cn- 1 of more than 30 2Ø
In the first step or stage of the present process in which the initial polypropylene sequen~e is formed, the amount of propylene polymerized is only 70% by weiyht or less of the polypropylene charged, leaving 30% or more available for the second (EP) or third 35 ~EP/P) steps. Typically the amount of propylene polymerized in the first step represents less than S0%, frequently not more than 30%! of the polypropylene charged in the first step.

.. -8-The thermoplastic elastomers of the invention are prepared by sequen~ial polymerization using a catalyst system ~f the kind des-cribed in United States patent 4, 298, 721, Borghi et al ., No~ . 3, 1981, V . S . patent 4,107,414, Giannini et al. Aug. 15, 1978 or European Patent Application 0 012 397, Phillips Petroleum Co., June 25, 1980. As described in United States patent 4,~98,721, suitable catalyst comprises the product obtained by reactin0 an addition compound of a halogen-containing compound of di-, tri- or tetra-valen~ titanium and an electron-donor compound, ~he addit~`on com-pound being supported on a sarrier comprising an activated anhy-drous magnesium dihalide and having in the supported state in its X-ray powder spectrum a halo in the place of the most intense diffraction line of the X-ray powder spectrum of the corresponding non-activated halide, with an addition and/or substitution produc~
of an electron-donor compound (or Lewis base) with an aluminium trialkyl, or an addition product of an electron donor compound with an aluminum-alkyl compound containing two or more aluminium atoms bound to each other through an oxygen or nitrogen atom, prepared by reactiny 1 mole of an aluminium alkyl compound with from 0.1 to 1 mole of an ester of an organic or inorganic oxygen-containing acid as the Lewis base, a di- or a poly-amine, or another Lewis base if the titanium compound contained a di- or pnly amine as electrsn-donor compound, t:he titanium compound content being less than 0.3 g of titanium per mole of the total amount of electron-donor com-pound in the catalyst, and the molar ratio of the halogen-containing titani~un compound to the aluminium alkyl compound being from 0.001 to 0.1.
As described in IJ . S . patent 4 ,107, 414, the catalyst is com-prised of the follow~ng components:
~a~ an addition and/or substitution reaction product of an electron-donor c~mpolmd (or Lewis base~ selected from the group consisting of an ester ~ an oxygenated organic or inorganic acid wi~h an Al-trialkyl compound or with an Al-alkyl compound containing two or more Al atoms linked together through ~ oxygen or a nitrogen atom, the amount of Al-alkyl compoun~ contained in a combined form with the ester in catalyst-forll~ing compon~nt (a) I I~
", !^` ` 1'~(1'7~1~3 g ~: being from 0.05 to 1.0 mole per mole of the starting Al-compound;
and ~ (b) the product ob~ained by contacting a Ti compound selected from the gro~lp consisting of halogenated bi-, tri-, and 6~ 5 tetravalent Ti compounds and complexes of said Ti compounds with ~- an electron-donor compound, with a support which comprises j ~s the essential support material thereof, an anhydrous bihalide of M~
' or Mn in an active state such that the X-rays powder spectrum of ,~ component (b) does not show the most in$ense diffraction lines as ,. 10 they appear in the X-rays powder spectrum of normal, nonactivated Mg or Mn bihalide, the X-rays powder spectrum of component (b) showing a broadening oI said most intense diffraction lines, and component (b) being further characterized in that the amount of Ti compound present therein, expressed as Ti metal, is less than 0 . 3 g-atom per mole of the total amount of the electron-donor compound present in a combined form in the catalyst and the catalyst being additionally characterized in that the Al/Ti molar ratio is from 10 to ' `~ 1, 000 .
Also suitable is the catalyst of European Patent Appli~a-tion 0,012,397 which may be described as forrned on mixing:
(A) a catalyst component (A) formed by milling (1) a magnesium halide or manganous halide wi~h ; (2) at least one catalyst adjuvant selected from (a) hydrocarbyl metal oxides of the formula M(OR)n wherein M is aluminium, boron, magnesium, titanium or . zirconium, n is an integer representing the valence of M and ranges from 2-4, and R is a hydrocarbyl group having from 1 to 24 carbon atoms per molecule, (b) organo phosphite of the formula ' R2 o / H : ~
\p - - O ~'-. ~2 O/
`' .

wherein R2 is an aryl, aralkyl, alkaryl or haloaryl group having from 6 to 20 carbon atoms, 12u7483 . -10-(c) aromatic phenols of the formula HOR1 wherein R1 is an aryl group containing from 6 to about 20 carbon atoms, (d) aromatic ketones of the ~ormula s :' ~ s R
. ~4 - C -R5 .

wherein R4 is a thiophene, aryl or alkyl group and R5 is an aryl group containing 6 to 20 carbon atoms, (e) organo silanols of the formula : :;

5j 0}1 , ~:
":;
wherein R6, R7 and R8 are the same or different and are hydro-carbyl groups containing from 4 to 20 carbon atoms, (~) organo phosphates and phospines of the formula . /R9 , . Rl_ p =:C O
\Rll 20 wherein each R in the same or different hydrocarbyl or hydro-carbyloxy group containing from 1 to 20 carbon atoms, ~) aromatic amines of the formula ~ .
wherein R5 is an aryl group having from 6 to 20 carbon atoms and ` 25 R12 is hydrogen or an aryl group having from 6 to 20 carbon . atoms, 1 Zt) ~ 48 3 ~' ', ! .
(h) oxygenated terpenes selected from among carvone, dihydrocarvone, carvenone and carvomenthane, triarylphosphites having from 6 to 24-~
!-~ carbon atoms in each aryl group, and -~c: 5 (j) halogen-containing organo phosphorous compounds of the formulae ~'t' PX3 a(OR )a' R3\ >p - X3 b and ' ¦, < / <xl where R3 is an aryl group containing from 6 to 20 carbon atoms, X
15 is a halogen, a is 1 or 2 and b is zero or 2, . ~o ~orm a milled composite wherein the molar ratio of (1 to (2) ranges from 4:1 to 100:1;
(3~ trea~ing ~he composits obtained from (1) and (2) wi~h a tetravalent titanium halide for a period of time sufficient to 20 incorporate titanium tetrahalide in at least a p~rtion of the surface o~ said milled component; and (B) a cocatalyst component comprisin0 at least one o~ an organoaluminum compound and an organoaluminum monohalide where-in the molar ra~io of component (B) to titaniusn compound ranges 25 from 0 . 5 :1 to 2000 1 and the amount of titanium percent in the finished catalyst ranges from about 0.1 to about 10 weight percent ' based on the dry composits.
In a preferred process for preparing thermoplastic elactomers by sequential polymerization in accordance with the inven~ion there 30 is employed a catalyst system (hereinafter referred to as Preferred Catalyst Sys~em I) made by reacting:
i .. ..

(a) a catalyst which is an addition compound of titanium tetrachloride with an alkyl benzoate ~methyl benzoate, or, more preferably higher alkyl benzoates), supported on an anhydrous magnesium dihalide and ground to give particles below 1 m~cron in siæe; with `
(b~ a cocatalyst which is a trialkyl aluminum modified by reaction with alkyl p-substituted benzoates having Hammett sigma values which are zero or negative ~electron-rich substituents).
Two preferred examples are ethyl anisate and ethyl p-t-butyl ben-zoate.
The molar ratio of titanium tetrachloride to alkyl benzoate in (a) is 1.1 to 1. The weight ratio of magnesium dlhalide to the complexed titanium compound is 4 to 1 or higher. The molar ratio of trialkyl aluminum to benzoate ester in (b) is from 2 to 1 to 10 to 1. The molar ratio of aluminun to titanium is at least ~û to 1, e.g. from 50 to 1 to 200 to 1 or even higher.
In another preferred practice of the sequential polymerization method of the invention there is employed a catalyst system (here-inafter referred to as Preferred Catalyst Systems II) which may be described as a TiCl4 supported on MgCl2 and modified by an aro-ma tic hydroxy compound . The phenol can ~e phenol itself, alpha-naphthol, beta-naphthol, p-chlorophenol, p-methylphenol (p-cresol) and the other cresols, etc. The catalyst is prepared by grinding the MgCl 2 and phenol in a vibratory ball mill or similar apparatus for from 16 to 72 hours, then treating this mix~ure with excess TiCl4 in a solvent at elevated temperatures. Decantation of the solvent followed by two washings with fresh solvent and drying of the precipitate (all under N;2) gave the desired catalyst. The weight ratio of MgCl2 to phenol is 4/1 to 100J1. The mole ratio of MgCl2 to TiCl4 is 2000/1 to 14/1.
The cocatalyst system is the same as described above in con-nection with Preferred Catalyst System I, except for the fact that the cocatalyst and modifier do not have to be pre aged. In fact aging for 30 minutes appears to reduce catalytic activity. The cocatalyst system contains an aluminum alkyl modified by an alkyl p-substitutedbenzoate. The para substituent is hydrogen or an electron donating group. (Hammet sigma value is either zero or ,,, negative). The ratio of A.l to modifier is 2/1 to infinity.

)7~L~3 -:L3-It will be noted that Preferred Catalyst System II is essentially ~he same as Preferred Catalyst System I except that in Preferred Catalyst System II a phenol is substituted for the alkyl benzoate in (a~ of Preferred Catalyst System I.
The polymerization is typically conducted at a temperature of from 20 to 80C or even higher, for the propylene step and from -10 to 80C for the ethylene-propylene step. The preferred procedure is to heat the polymerization system to 55S:~ and begin the polymerization keeping the temperature below 77~C. The second step, the copolymerization of ethylene and propylene, is usually carried out between 60 and 77C and the third step, if present, is usually kept between 60 and 77C.
The first polymerization step can require as little as 10 to 25 minutes, the second step as little as 15 to 45 minutes, and the last step, if present, as little as from 10 to 25 minutes. Of course, longer times are also possible. The precise reaction time will de-pend on such variables as the reaction temperature and pressure, the heat transfer rate, etc.
The polymerization is preferably carried out in organic solvent such as a hydrocarbon fraction ~boiling, for example, bet~reen 3d and 60C), such as hexane. Other solvents such as heptane, octane, or hiyher alkanes can be used. Aromatic hydrocarbons can also be used, benzene and toluene being two examples. The poly-mers produced are only partially soluble in the solvent, thus yivins~
one a slurry type polymerization. The solvent is "inert" in the sense that it does not adversely interfere with the catalyst or the polymerization reaction. An excess of propylene over and above the propylene which takes part in the polymerization, can serve as the reaction medium; isobutylene is another eacample of a suitable reaction medium.
The fact that the polymers are not completely soluble in ~e solvent system allows one to run at high solids concentration since the viscosity of the reaction medium is low for a given solids con-tent thus helping to facilitate heat transfer to keep the exothermic polymerization under control. The polymeriæation gives rise to a small particle type slurry (easily dispersed) so that handling prob-lems are facilitated and transfer of the reaction mixture from the reactor to finishing equipment is easily accomplished.

~Z0~ 3 The work-up of the polymer involves addition of a short-stop;
addition of antioxidants, steam-floccing, or vacuum drum drying, as in conventional practice . The efficiencies of polymerization (2Q, 000 to 100,000 g polymer/g of titanium) make a washing s$ep unneces-sary unless it is desired to minimize aluminum residues. If neces-sary, a washing step can be instituted. The crumb obtained can be dried and diced for use in injection molding or prepared in other forms such as flakes by using conventional commercial equipment.
Oil extension will give rise to soft polymers w~th excellent tensile to hardness ratios.
The examples below illus trate the preparation of the catalyst and the practice of the invention.

PREPARATION OF PREFERRED CATALYST SYSTEM I

A ) Preparation of Ti Complex An apparatus consisting of a one liter 3-necked flask, a me-chanical stirrer, an addi~ion funnel, a thermometer, and a reflux condenser which had been oven dried at 110C was equipped with an adapter at the top of the condenser to keep the apparatus under a N2 stream. The N2 exited through a bubbler con~aining a small amount of oil. Heptane (450 ml) and TiCl4 (48 ml, 82.8 g, .436 moles) were added under N2 and after heating to 65C, the drop-wise addition of a solution of 52 ml (54 . 7 9, . 364 moles) of ethyl-benzoate in 50 ml of heptane was begun. After ~he addition was comple~e, the reaction mixture was stirred for 1 hour. The hep~ane was stripped off under vacuum and the solid complex which fumes in air was put in a taped bottle in the N2 glove box. The complex appears to be active indefinitely in the absence of air.

B) Formation of Supported Catalyst Co~
An oven dried polypropylene wide mouthed bottle containing ceramic balls was half-filled with a mixture of 4 parts of anhydrous MgCl2 or every 1 part of catalyst complex under N2. The self-locking cover was taped to further protect the contents and the bottle put in a vibrating ball mill for at leas~ 15 hours and usually ?~ 30 hours. The supported complex was separated from the ceramic 1~07~3 balls in a glove box and stored until needed. The dry complex appears to be stable at least for 3-5 months. When it is dispersed in solvent it begins to lose activity after about 4 days. One gram of the complex contains 28 mg of titanium.

5 C) Formation of_Cocatalyst Complex The 25% Et3Al ~1.6 M) was reacted in hexane or helptane w~th the required amount of ethyl anisate (10-40 mole O, keeping the temperature below 50C. The clear yellow solution was aged for hour before adding to the polymerizing medium. The same was lG done for ethyl p-t-butyl benzoate when used in place of ethyl anisate. The use of other modifiers gave much poorer results.
Leaving out the modifiers gave rise to high yields of low molecular weight polymers with lower tensile values.

EX~MPLES 1-7 AND COMPARISON EXAMPLE 1 In a 20 gallon jacketed pressure reactor equipped with a sealed mechnical stirrer were added 40 Kg of hexane followed by 4 Kg of propylene. The contents were heated to 130F. Aged cocatalyst was then addkd consisting of 250 ml of 1.6 M. Et3Al (400 millimoles) diluted with 400 ml of hexane and reacted with 16 . 7 g ethyl p-t-20 butyl benzoate (EPTBB ) (equivallen~ to 86 . 4 millimoles of ester~ to give a mole ratio of 0 . 216 oE ester ot AlEt3 . The solution of co-catalyst had been aged ~ hour before addition to reactor.
Addition of 6.4 g (180 mg Ti) of supported catalyst dispersed in hexane initiated the reaction and propylene was fed in to main-25 tain th~ pressure at 50 psig. A regulator valve was used to con-trol the pressure. The temperature rose from 130F to 142F even with coolin~ on. After 15 minutes the propylene feed was turned off and CP ethylene fed rapidly till 400 g of ethylene had been introduced . The pressure at this point was 55 . 2 psig . Ethylene 3û and propylene at a 1 ~o 1 molar ratio were fed in ~o maintain this pressure. With the introduction of E/P, the temperature climbed to 175F even with full cooling. After 45 minutes l~he temperature was 148~ . The monomer feeds were turned of E and the reaction mix-ture was dumped, the reac~or was rinsed with hexane, the rinse 35 was added to the dump and the total short-stopped with 100 9 ~L .A ~ ._ _ . . . ~ _ .. _ _ _ _ .. .. _ .. _ . _ .. _ . _ _ .. . ~.. ~ .. : ~
U7~33 -:L6~

isopropyl alcohol. At this point 40 g of antioxidant was added with mechanical stirring and the polymer suspension was stearn-flocced to recover the crum~. Drying and massing on a mill to give homo-geneous product gave a yield of 7730 g (efficiency = 42,944 g 5 polymer per gram of titanium).
The pertinent data for this example are in Table I under Example 1. It is seen that one had 90% utilization of the total ethylene added and 75% utilization of the total propylene added.
The polymer has 45% propylene crystallinity as measured by 10 X-ray with 15% ethylene content. The Tg is -48C and the melting point by DTA of the polymer is 154C, indicating the presence of isotactic propylene segments. The injection molded sample has a tensile of 1736 psi at 520% elongation. The 250~F properties are adequate especially when compared to the United States pa$ent 15 4,298,721 one-step product with no high temperature tensile and a meltin0 point of 248F (120C).
Examples 2-7 which were run under essentially identical con-ditions are recorded in Table 1.
Example C-1, which is a comparison or control example outside the scope of ~he invention, is included to show the difference between polymer made in accordance with the one-stage process of United States patent 4, 298, 721 and the thermoplastic elastomer of this invention. It is evident that at 250F the tensile of the Example C-1 polymer for all practical purposes is zero.

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0~74~33 In a 20 gallon reactor as in Example 1 were added 40 Kg of hexane and 4000 g of propylene. The solution was then heated to 132~F. A prereacted soution of 400 millimoles of Et3Al and 146 5 millimoles of ethyl anisate in hexane was added to the reactor after aging 1-2 hour and the polymerization initiated by adding the Ti4 catalyst (180 mg . titanium) . The pressure was 46 . 5 psig at this point and propylene monomer was fed as needed to keep pressure at this point. The reaction exothermed to 142F after ten minutes and 10 after 25 minutes the pressure was at 47 psig and the temperature was 126F. The propylene was turned off and ethylene added to increase the pressure to 55.0 psig. The pressure was kept at this level by feeding in ethylene and the second phase run for 25 minu-tes. The temperature was 146F and the pressure 55.3 psig.
The final 25 minutes was run with only propylene monomer where the pressure dropped to 40 and the temperature to 110~F.
The polymer slurry was dumped, the reactor rinsed with hexane and added to the dump. The polymerization was short-stopped with isopropanol (100 g.) and antioxidant added with stir-20 ring.
The polymer was recovered by steam floccing, dryin~ undervacuum and massing on a mill to assure a homogeneous mix. The yield was 4,500 g. (24,772 g/of polymer per g of titanium).
The physical properties are in Table Il under Example 8. It 25 is seen that the properties like tensile are very good. The h;gh temperature tensile is also very good. Monomer utilization is good for ethylene and fair for the propylene.
Examples 9-13 in Table II are more or less run in a similar manner to give the properties described in Table II. Again, the 30 high temperature properties are excellent for materials of high hardness and become poorer as the hardness decreases as expected.

7~o-TABLE II
~EACTOR TPO'S; PILOT PLANT RUNS 0~ - -EXAMPIE # 8 9 10 11 12 13 COCATALYST Et3Al/EA Et3Al/EA Et3Al/EA Et3Al/EA Et3Al/EpTBB Et3Al/EA
MMoles/MMoles 400/140 490/140 400/140 400/140 400/85 400/140 CATALYST (mg ~f 180 180 180 180 180 18Q
Ti) 10 TIME (MIN.~ 25/25/25 H2 PSI O 0 2.5 7.5 2.5 2.5 YIELD (g.~ 4500 4630 5440 4880 8940 4200 EFFICIENCY 24,772 25,700 30,239 27,128 49,667 23,556 ~ ML-4 @ 257 139 130 95 58 34 70-95 ; 15 BROOKFIELD CP - - - 105 875 600 % ETHYLENE 8.7 22.4 21.2 32.1 33 35.7 [n]135 3.67 4.85 2.0 1.82 1.67 2.17 % CRYST. (X-RAY) 39 37 37.1 22.7 27.3 38.7 Tg --45 -55 -46 -60 -53 Tm 154 156 162 159 162 160 % UTIL. OF E. 97 100 1()0 97 100 91 % UTIL. OF P. 49 45 52 40 76 33 INJECTION MOLD
R.T. SHORE A 95 93 89 89 75 91 100% NOD PSI 2216 1631 1187 774 491 820 h ELONG. 537 390 653 823 787 677 FLEX. MOD PSI7~ 69,600 22,500 14,800 l6,000 4500 12~300 30 250~

100~ MOD PSI 277 253 102 77 31 113 ELONG % 900 650 NB NB 960 NB
* As determined by ASTM D-790-71, Nethod B.

:~Z~)74~33 The oil extension of these thermoplastic elastomers gives materials which are softer, and yet maintain good tensile values.
We are able to get Shore A hardness values of below 70 and keep 5 our tensile values above 600 psi. This is difficult to do with TPO's as a group . The oil used in these experiments is Tufflo ( trade-mark) 6056 and is a parafinnic hydrocarbon oil *om Atlantic Richfield. The oil is mixed on a mill or on a Banbury with the stabilizers and the resultant product injection molded. The prop-10 erties of the oil extended material of Example 15 are recorded inTable III along with similarly carried out Examples lfi~21.

TABLE I I I
OIL EXTENDED ~PO POLYMERS

EXAMPLE # 14 15 16 17 _ 18 19 20 AMOUNT 80.0 80 80 80 80 80 80 TENSI~E PSI ~27 1343 1375 1375 735 1623 106~
: OIL TUFFL0 TUFFLO TUFFLO TUFFLO TUFFLO TUFFLO TUFFLO
~056 6056 605~ 6056 ~056 6056 ~055 20 AMOUNT (pph) 20.0 20.0 20.0 40.0 20 20 20 INJECTION MOLD

TENSIL~ PSI 563 1784 1074 697 473 1234 751 ELONGATION % 773 810 737 720 797 337 430 100% ELONG. SET 30 30 42 40 30 19 20 : 100% MOD 296 941 582 353 209 804 453 TENSILE/HARDNESS 11.7 23.2 13.1 10.9 8.~ 15.8 11.0 Thermoplastic elastomer samples, Examples 21-24, within the contemplation of this invention were analyzed to determine their spectral characteristics. The results of these tests are summarized below in Table IV. Included in the table are Comparison Examples t79 C-2, C-3 and C-4 illustra~ive of ethylene-propylene polymers of the prior art, TABLE IV

EXAMPI,E # 22 23_ _24* C-2** C-3 C-4 TYPE P/EP P/EP PIEP/P EP Block EP P/EPDM
% ETHYIENE 29.4 18.0 22.0 30.7 25.0 27.0 2.29 1.73 4.85 2,43 2.~7 1.26 Z CRYS (X-RAY) 41.1 37.0 30.9 49.0 31.0 Tg (C) -50 -35 ~45 -46 NONE -58 10 Tm (C) 161 162 156 120 162 161 11.88/12.18 ~IR RATIO) 26.5 12.1 9.6 3.4 14.0 14.0 810/84û (RAMAN RATIO) 1.589 1.2168 1.486 0.923 1.5401 1.566 2880/2û50 (RAMON RATIO) 2.146 2.3510 2.351 2.03~ 2.235 1.854 FLEXtlRAL MOD (PSI ) 25, ooa 18,20û 22,000 6,500 112,800 24,000 15 P~.T. TENSIL~ STR (PSI) 1,643 2,953 2,121 1,291 2,913 970 El.ONGATION (%) 650 610 390 620 97 330 * Same Polymer as Example 9 Same Polymer as Example C-l The data in Table IV distinguishes the thermoplastic elastomers 20 of the present invention from those of the prior art. As seen, the ratio of the absorp~ion intensits7 in the IR spectrum between the band at 11.88 microns and the band at 12.18 m~crons, discussed in U.S. Patent 4,298,721, for polymers within the contemplation of this inven~ion is more than 7Ø Similarly the ratio of the intensities of Z5 the band at 810 cm 1 and the band a~ 840 cm~1, in the Raman spectrum, for polymers within the contemplation of this invention, is more than 1.0, while the.ratio of the intensity of the band at 2880 cm 1 to the band at 2~50 cm~1 for the elastomers of this invention is more than 2Ø Thermoplastic elastomers of the one-30 step process, repre~entative of the prior art/ as disclosed by U.S.
Patent 4,29B,721, and illustrated by Example C-2 in Table IV
above, yield an equivalent IR ratio of less than 7 . O and a Raman spestra r~tio of less than 1Ø

h.................................. . ....................... ... ......
lZV'74~3 The one-stage polymers of IJ.S. Patent 4,298,721 are futher-more distinguished by a differential thermal melting point of only 120C, helow the requirement of the thermoplastic elastomers of the present invention, which are characterized by at least one differ~
5 ential thermal melting point of at least 150~C.
Comparison example C-3 is illustrative of plastic block copoly-mers of the prior art. Although this sample is not distinguishable over the polymers of this invention by analysis of the spectral data, it is clearly distinguished ~y the absence of a glass transition 10 temperature characteristic of crystalline plastics. Thermoplastic elastomers all possess a glass transition temperature.
Crystalline plastics, exemplified by Example C-3, are similarly distinguished by their high flexural modulus, typically above 100,000 psi, in this example 112,800 psi and low elon~ation, usually 15 less than 150%, in this example 97%. These properties distinguish thermoplas~ic elastomers of this invention which typically have a flexural modulus of less and oftentimes considerably less, than 100,000 psi. Thermoplastic elastomers of this invention are similarly distinguished from block copolymer plastics by their high elonga-20 tion, characteristic of rubbery polymers. Thermoplastic elastomers of this invention have elongations in excess of 150%.
Comparison Example C-4 is dlirected to a typical thermoplastic elastomer of the prior art. Often thermoplastic elastomers of the prior art are physical blends of a crystalline plastic, usually, as in 25 Comparison Example 3, polyproplyene, and an elastomer, usually, as in Comparison Example 3, EPDM. These polymers are distinguished from the thermoplastic elastomers of the present invention by their Raman spectrum characteristics. Specifically, the ratio of the intensity of the band at 2880 crn ~ l~o the intensity of the band at 30 2850 cm 1 in the Raman spectra of physically blended thermoplastic elastomers is less than 2 O 0 . The same ratio for the thermoplastic elastomers of the present invention is more than 2Ø

EXAMPI.E 26 Catalyst Preparation This example utilizes Preferred Catalyst System II. Anhydrous MgC12 ~45 g) is mixed with purified phenol (6.3 g) then ground for h...................... . . ..................... ... .. .. . . . .. ... ... . . ..
lZ0'748 31 hours . The material was sif ted into a 500ml 3 necked round bottom flask in an inert atmosphere and trea~ed w~th 150 ml of heptane and 18 ml of TiCl4. The mixture was heated at 100C for 1 hour, cooled, the liquid decanted, and the precipitate washed two time with fresh solvent. All the above operations were done under dry nitrogen. The precipitate was then heated to 50C and dried in a steam of nitrogen.

20 Gallon Reactor Run To a clean, and dried reactor was added 40 Kg of hexane and 4 Kg of purified propylene. The solution was heated to 135F and then the Et3A1 (80 mm) ethyl p-t-butylbenzoate (~3 mm) and the Ti4 phenol modified catalyst (0.8 g = 20 mg Ti) were added. The pressure at this point was 64 psig. No propylene had to be fed to maintain this pressure. After 15 minutes 400g of ethylene were added rapidly. The pressure was now 86 psig. The temperature rose to 160F and was maintained at this point. After 30 minutes during which ethylene and propylene were fed at a 4/1 molar ratio to maintain the pressure, the reaction mass was dumped. The reactor was rinsed with hexane and the hexane added to the reac-tion mixture. Addition of isopropyl alcohol to short-stop the reac-tion was followed by addition of A0449 (trademark; antioxidant) and finally isolation of the polymer by steam floccing. The polymer was dried under vacuum. The yield of material was 2,070 g (100,000 g polymer/g of Ti~. The % ethylene was 24 and I.V. in tetralin @
135C was 5.30. The ML-4 @ 257F was 10g.
The advan~ages of ~his catalyst are higher efficiency ~lower amounts of catalyst cut catalyst cost and eliminate necessi~ to wash polymer cement) and the elimination of aging step in cocatalyst preparati~n.

This example illustrates the fact that only 70% or less of the propylene charged in the first step becomes polymerized in that step (as measured by determining total solids), leaving 30% or more available for the second step (F.P) or third step (EP~P~.
(16A) Charge 4000 g propylene, 40,000 9 hexane and 600 g of total catalyst solution as previously ~escribed. Once polymerization ~ILZO'7~33 starts additional propylene (1,105 g) is added continuously to maintain pressure. At the end of this first step the total solids is 1252 g of polypropylene.
1252 g polypropylene 100 - 24.5% of propylene 5 5105 g propylene monomer charged x used in first step.
Further additions of propylene are added later together with ethy-lene to form EP and again in the third step to form more polypro-pylene .
(16B) Charge 4000g propylene, 40,000 g hexane and 560 g of 10 total catalyst solution. Add an additional 1,690 g propylene during the first step to maintain pressure. 1295 g of polypropylene is formed .
1295 g polyprop~lene 100 = 23% of propylene 5690 g propylene charged x used in first step

Claims (23)

What is claimed

1. A thermoplastic elastomer comprising a sequential-ly prepared polymer having (A) polypropylene segments showing crystallinity of the isotactic polypropylene type and (B) amorphous segments which are elastic ethylene-propylene materials, said segments (A) and (B) being only partially block copolymerized to each other, said polymer comprising 60 to 95 weight percent propylene, said polymer characterized by a ratio of the absorption intensity in the infrared spectrum of the band at 11.88 microns to the band at 12.18 microns of more than 7.0; a ratio of the intensity in the Raman spectrum of the band at 810 cm-1 to the band at 840 cm-1 of more than 1.0; a ratio of the intensity in the Raman spectrum of the band at 2880 cm-1 to the band at 2850 cm-1 of more than 2.0; a flexural modulus, at room temperature, of less than 100,000 pounds per square inch;
an elongation, at room temperature, or more than 150%; and at least one differential thermal analysis melting point of at least 150°C.

2. A thermoplastic elastomer in accordance with claim 1 char-acterized by a crystallinity value of from 15 to 45% as measured by X-ray.

3. A thermoplastic elastomer in accordance with claim 1 characterized by an intrinsic viscosity of from 1.5 to 6 measured in tetralin at 135°C.

4. A thermoplastic elastomer in accordance with claim 1 characterized by polypropylene segments with crystallinity of the isotactic polypropylene type and amorphous segments which are elastic ethylene-propylene materials, said segments and said amor-phous segments only partially block copolymerized to each other, the weight ratio of said polypropylene segments to said amorphous segments being within the range of from 10:90 to 75:25.

5. A thermoplastic elastomer in accordance with claim 4 wherein said polypropylene segments comprise 15 to 70% by weight, based on the total weight of propylene in said thermoplastic elas-tomer.

6. A thermoplastic elastomer in accordance with claim 1 including from 30% to 70% by weight of said thermoplastic elastomer extractable by boiling n-hexane.

7. A thermoplastic elastomer in accordance with claim 1 which is oil-extended.

8. A thermoplastic elastomer in accordance with claim 1 wherein said polymer is a propylene and ethylene-propylene polymer.

9. A thermoplastic elastomer in accordance with claim 1 wherein said polymer is a propylene, ethylene-propylene and pro-pylene polymer.

10. A method of making a thermoplastic elastomeric sequential polymer of propylene and (ethylene-propylene) or propylene, (ethy-lene-propylene) and propylene comprising contacting propylene in solution under polymerization conditions with a polymerization cata-lyst which produces polypropylene in which at least some of the polymer molecules have living polymer ends with a short life, there-after adding ethylene and propylene to the polymerization mixture to form ethylene-propylene copolymer sequentially therein, and optionally thereafter adding propylene to the reaction mixture to form sequentially additional polypropylene therein, the resulting polymer having (A) polypropylene segments with crystallinity of the isotactic polypropylene type and (B) amorphous segments which are elastic ethylene-propylene materials, the weight ratio of (A) to (B) segments being within the range of from 10:90 to 75:25.

11. A method as in claim 10 in which the polypropylene seg-ments (A) comprise 15-70% by weight of the total polymerized pro-pylene.

12. A method as in claim 10 in which less than 50% by weight of the propylene charged in the first step is converted to polypro-pylene.

13. A method as in claim 10 in which not more than 30% by weight of the propylene charged in the first step is converted to polypropylene.

14. A method as in claim 10 in which the said catalyst is a catalyst system comprising a titanium halide or a complex thereof with an electron donor supported on a magnesium or manganese halide, and a cocatalyst which is an organo aluminum compound or a substitution product or addition product thereof with an electron donor.

15. A method as in claim 10 in which the said catalyst is a catalyst system comprising:
(a) a catalyst which is a reaction product of titanium tetrachloride with an alkyl benzoate, supported on anhydrous mag-nesium dihalide; and (b) a cocatalyst which is a trialkyl aluminum modified by reaction with an electron rich substituted benzoate.

16. A method as in claim 15 in which (a) is ground to a par-ticle size below 1 micron, the alkyl benzoate is ethyl benzoate, the magnesium dihalide is magnesium dichloride, the trialkyl aluminum is triethyl aluminum, the electron-rich substituted benzoate is ethyl anisate or ethyl p-t-butyl benzoate, the molar ratio of titanium tetrachloride to alkyl benzoate in the catalyst (a) is 1.1 to 1, the weight ratio of MgCl2 to complexed titanium compound is at least 4 to 1, the molar ratio of trialkyl aluminum to benzoate in the cocata-lyst (b) is from 2:1 to 10:1 and the molar ratio of aluminum to titanium is from 50 to 1 to 200 to 1.

17. A method as in claim 16 in which the said electron-rich substituted benzoate is ethyl p-t-butyl benzoate.

18. A method as in claim 10 in which the said catalyst is a catalyst system comprising:
(a) a catalyst which is a reaction product of titanium tetrachloride with a phenol, supported on an anhydrous magnesium dihalide; and (b) a cocatalyst which is a trialkyl aluminum modified by reaction with an electron rich substituted benzoate.

19. A method as in claim 18 in which (a) is ground to a particle size below 1 micron, the magnesium dihalide is magnesium dichloride, the phenol is phenol itself, the trialkyl aluminum is triethyl aluminum, the electron-rich substituted benzoate is ethyl anisate or ethyl p-t-butylbenzoate, the weight ratio of magnesium dichloride to phenol is from 4:1 to 100:1, the molar ratio of magne-sium dichloride to titanium tetrachloride is from 2000:1 to 14:1, and the mole ratio of aluminum to titanium is at least 2:1.

20. A method as in claim 16 in which the polymer produced is a sequential propylene and (ethylene-propylene) polymer, the polymerization temperature being from 20° to 80°C in the first step and from -10° to 80°C in the second step.

21. A method as in claim 16 in which the polymer produced is a sequential propylene, (ethylene-propylene) and propylene poly-mer, the polymerization temperature being from 55° to 77°C in the first step, from 60° to 77°C in the second step and from 60° to 77°C in the third step.

22. A method as in claim 19 in which the polymer produced is a sequential propylene and (ethylene-propylene) polymer, the polymerization temperature being from 20° to 80°C in the first step and from 10° to 80°C in the second step.

23. A method as in claim 19 in which the polymer produced is a sequential propylene, (ethylene-propylene) and propylene poly-mer, the polymerization temperature being from 55° to 77°C in the first step, from 60° to 77°C in the second step and from 60° to 77°C in the third step.