WO1998033842A1

WO1998033842A1 - Process for the reaction of polyolefins with hydrosilanes

Info

Publication number: WO1998033842A1
Application number: PCT/NL1998/000058
Authority: WO
Inventors: Koen Jan Gerarda Janssen; Wilhelmus Gerardus Marie Bruls; Theodoor Wilhelm Leonard Rauch; Michel Paul Van Boggelen; Gerardus Arnoldus Rademarkers
Original assignee: Dsm N.V.
Priority date: 1997-01-31
Filing date: 1998-01-28
Publication date: 1998-08-06
Also published as: AU5884198A

Abstract

A method for the preparation of branched polyolefins in the form of a comb, star, nanogel and structural combinations thereof in which polyolefin prearms are reacted with a polyhydrosilane in the presence of a hydrosilation catalyst in which the catalyst is dosed to the reaction mixture at an elevated temperature to promote the addition of Si-H groups across the ethylenic unsaturation of the polyolefin prearm. The method of the invention can be carried out optionally in the presence of an accelerator to promote the hydrosilation reaction.

Description

PROCESS FOR THE REACTION OF POLYOLEFINS WITH HYDROSILANES

This invention relates to branched polyolefin polymers, and more specifically to a process for use in the production of branched polyolefin polymers compri- sing a silicon containing polymeric backbone with branches extending therefrom in which the branches are formed of polyolefins wherein the branched polymers are produced by a hydrosilation reaction between polyolefin prearms with a hydrosilane containing compound.

BACKGROUND OF THE INVENTION

In co-pending application Serial No. 511,402 filed August 4, 1995, and co-pending application Serial No. 683,518 filed July 12, 1996, there is described a number of branched polyolefin polymers in the form of a comb, star, nanogel or structural combinations thereof wherein a plurality of polyolefin arms are linked to a polymeric backbone to provide a highly branched structure in which the properties can be conveniently tailored to the application for which the polymer is used. One embodiment disclosed in those co-pending applications includes those branched polymers containing polyolefin arms bonded to a polymeric backbone in the form of polyhydrosilane polymers containing a large number of repeating units containing a silicon-hydrogen bond. In general, those silicon-containing polymers have a number of units of the general formula :

wherein X is a heteroatom, such as O, P, S, N, Si or one or more carbon atoms either as part of an aliphatic or aromatic group and R is hydrogen or an organic group .

One illustration of the backbones suitable for use in the preparation of branched polyolefin polymers are polyhydro-siloxanes derived from an alkylhydrosiloxane end-capped with either a hydrosilane functionality or an alkylsilane functionality. Such compounds have the general formula:

wherein R_x to R₇ is each independently hydrogen or an organic group; preferably, R_x and R₂ can be either alkyl, aryl or cycloalkyl; R₃ can be either hydrogen, alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy; R₄ is hydrogen, alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy; R₅ and R₆ are alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy and R₇ is hydrogen, alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy; n is an integer having a minimum value of about 10, and preferably 25 or higher. Such polyhydrosiloxanes, as is well-known to those skilled in the art, are commonly available from a number of companies including Dow Corning and Rhone Poulenc.

As described in the foregoing applications, the branched polymers utilizing a hydrosilane- containing backbone are prepared by reacting one or more of the hydrosilanes with a polyolefin prearm preferably containing terminal unsaturation, either in the form of vinyl, vinylidene, vinylene groups and mixtures thereof, in the presence of a suitable catalyst wherein the silicon-hydrogen bond adds across the double bond of the prearm. That reaction can be illustrated for those prearms containing terminal vinylidene unsaturation according to the following equation:

while a reaction with a terminal vinyl unsaturation proceeds according to the following equation: EP

H !

I CH₂ CH₃ - CH - EP

- 0 - Si - + EP - CH = CH₂ → I and/or |

I CH₂ - 0 - Si - CH₃ I I

- 0 - Si - CH₃

1 1

CH,

wherein EP represents the remainder of the polyolefin pre-arm.

As described in the foregoing applications, that hydrosilation reaction can be carried out in the presence of a solvent along with a catalyst to promote the reaction. Suitable hydrosilation catalysts to effect that addition reaction are known in the art and include compounds of metals from Groups 8 to 10 of the Periodic Table, typically catalysts based on palladium, platinum or nickel. It has been found that the reaction between the Si-H bond of a polyhydrosilane backbone polymer and the ethylenically unsaturated polyolefin prearm proceeds somewhat slowly, particularly when the polyolefin prearm is dissolved in a solvent at low concentrations (less than 50 wt %) and/or when the polyolefin prearm has a number average molecular weight or Mn greater than about 10,000 g/mol. Using a dilute concentration of polyolefin prearms, the reaction rates are frequently too slow for commercial utilization, often requiring many hours to days of reaction time. In addition, since the polyolefin prearms are typically dissolved in a solvent to form a relatively dilute solution, the reaction produces branched polymers having polyolefin arms bonded to a backbone which themselves are dissolved in dilute solutions. Thus, commercial practice of this technology would require techniques to remove and recycle large volumes of solvent, which complicate the process and increase production costs. Apart from the foregoing deficiencies, the use of solvents which are more readily separable from the polymers by known commercial processes has generally dictated relatively low reaction temperatures which have, in turn, increased the time required for the reaction.

It is accordingly an object of the present invention to provide a method for the hydrosilation reaction between a polymeric backbone having hydrosilane groups with a polyolefin prearm containing ethylenic unsaturation to produce a branched polymer which overcomes the foregoing disadvantages.

It is another object of this invention to provide a method for carrying out the reaction of a polymeric backbone having hydrosilane groups with a polyolefin prearm containing ethylenic unsaturation to produce a branched polyolefin at significantly reduced reaction times and elevated temperatures. It is another object of the invention to provide a method for carrying out the reaction of a hydrosilane-containing backbone with a polyolefin prearm containing ethylenic unsaturation wherein the reaction can be carried out in bulk, either in the absence of a solvent or in the presence of limited quantities of solvent .

It is yet another object of the invention to provide a method for the reaction of a hydrosilane- containing polymeric backbone with a polyolefin prearm containing ethylenic unsaturation in the presence of a catalyst and an accelerator for the reaction in which the reaction times are significantly reduced.

SUMMARY OF THE INVENTION

The concepts of the present invention reside in a method for carrying out in dilute solution or in bulk the reaction of a hydrosilane-containing silicon polymer with a polyolefin prearm containing ethylenic unsaturation in the presence or absence of an acce- lerator for the preparation of branched polyolefin polymers, wherein the polyolefin arms become attached to a silicon polymer as the backbone to form a highly branched polymer in the form of a star, comb, nanogel and structural combinations thereof. In the practice of the present invention, the polyolefin prearms containing ethylenic unsaturation are reacted with a compound containing a plurality of hydrosilane groups in the presence of a catalyst to promote the addition of the Si-H groups across the ethylenic unsaturation of the polyolefin and optionally in the presence of an accelerator for that reaction. It has been found that, reaction times can be significantly reduced for both the dilute solution reaction and the bulk reaction provided the catalyst is dosed to, that is, it is mixed with, the reaction mixture containing polyolefin prearms and polyhydrosilane at elevated temperatures. It has also been found that, when using the appropriate catalyst and accelerator, the reaction can be carried out efficiently and at significantly reduced reaction times under both dilute solution or bulk reaction conditions. As used herein, the term "bulk reaction conditions" refers to and includes a reaction of either a solid or a liquid polyolefin prearm polymer either in the absence of a solvent or in the presence of limited quantities of solvent. In general, where a solvent is used in the practice of the present invention, the concentration of polyolefin prearm in the solvent is at least 10% by weight, preferably at least 50% by weight, and most preferably 75% by weight or higher. The use of relatively concentrated polymer systems allows the reaction time to be significantly reduced; in addition, the bulk reaction conditions as described herein also permit the use of higher temperatures which likewise serve to reduce the time required for the reaction. In the practice of the invention, the reaction is carried out in the presence of a hydrosilation catalyst, and preferably a catalyst containing a metal from Groups 8 to 10 of the Periodic Table. Typical catalysts are based on palladium, platinum, nickel, rhodium or cobalt.

Accelerators used in the practice of this invention are preferably halogenated organic compounds including trichloroacetic acid esters, hexachloro- acetone, hexachloropropylene, trichlorotoluene or perchlorocrotonic acid esters. Such compounds promote or accelerate the reaction between the ethylenic unsaturation in the prearm and the Si-H group in the silicon containing polymeric backbone in the preparation of branched polymers. The accelerators effectively increase the coupling efficiency of both the bulk reaction and the conventional more diluted reaction in solvent.

The reaction can be carried out as desired in high intensity mixing devices such as melt processing equipment like a Banbury mixer or an extruder or reactors such as a Haake high intensity mixer or like equipment for blending solid and semi-solid reactants.

It has been found, in accordance with the practice of the invention, that the polyolefin prearms can be efficiently reacted with a polyhydrosilane containing silicon polymer to produce a branched polyolefin polymer to form a star, comb, nanogel and structural combinations thereof with an increased reaction rate when the catalyst or a combination of catalyst and accelerator are added to the mixture of polymers at elevated temperatures, in the range of 80 to 350 °C.

The reaction in accordance with the practice of this invention is far more efficient as compared to prior art processes.

DETAILED DESCRIPTION OF THE INVENTION

In carrying out the improved process of the present invention, polyolefin prearms containing ethylenic unsaturation are reacted with a polymeric backbone polymer containing Si-H groups whereby the Si-H groups add across the ethylenic unsaturation to form a branched polyolefin polymer in the form of a comb, star, nanogel or structural combinations thereof as described in the foregoing co-pending applications Serial No. 08/511,402 filed August 4, 1995 and Serial No. 08/683,518 filed July 12, 1996. As used herein, the term polyolefin prearm refers to a polyolefin polymer containing ethylenic unsaturation, preferably at its terminus or within the terminating monomeric unit, so that it can react with the Si-H bond of the silicon- containing backbone. That ethylenic unsaturation is preferably one of vinyl, vinylidene or vinylene unsaturation. Terminal ethylenic unsaturation is preferred to reduce steric effects resulting from reaction between two polymeric molecules.

The polyolefin prearms which can be used in the practice of the present invention depend in large measure on the properties desired in the branched polyolefin polymer. In most embodiments, it is generally preferred, that the polyolefin prearm be formed of a polyolefin containing terminal unsaturation in the form of either vinyl, vinylidene, vinylene, or mixtures thereof. Use can be made of polyolefin homopolymers, such as polyethylene and polypropylene, but it is also possible, and sometimes preferred, to employ copolymers of one or more 1- alkenes or to employ copolymers of one or more 1-alkenes with other unsaturated monomers copolymerizable therewith. In general, use is made of polyolefin prearms formed by copolymerization of ethylene and propylene or ethylene and/or propylene with at least one other 1-alkene. In addition, it is also possible to use, in combination with one or more of the monomers described above, one or more polyenes which either may or may not be functionalized. Also suitable as comonomers in the formation of the polyolefin prearms are functionalized ethylenically unsaturated monomers in which the functional group may be one or more polar groups capable of undergoing metallocene catalyzed polymerization.

The polyolefin prearms used in the practice of the present invention refer to and include polymers of l-alkenes generally, and preferably ethylene/ propylene copolymers or copolymers of ethylene and propylene with other 1-alkenes, as well as copolymers formed by the interpoly erization of ethylene, 1-alkenes and at least one other polyene monomer. Such polymers are themselves well known to those skilled in the art and are typically prepared by using conventional Ziegler or metallocene polymeriza- tion techniques well known to those skilled in the art . Both types of polymers hereinafter collectively are referred to as EP(D)M.

As will be appreciated by those skilled in the art, while propylene is a preferred monomer for copolymerization with ethylene and optionally a diene monomer, it will be understood that in place of propylene, use can be made of other 1-alkenes containing 4 to 20 carbon atoms. The use of such higher 1-alkenes together with or in place of propylene are well known to those skilled in the art and include, particularly, 1-butene, 1-hexene and 1-octene.

When using an interpolymer of ethylene, 1-alkene and a polyene monomer, use can be made of a variety of polyene monomers known to those skilled in the art containing two or more carbon-to-carbon double bonds containing 4 to 20 carbon atoms, including non-cyclic polyene monomers, monocyclic polyene monomers and polycyclic polyene monomers. Representative of such compounds include 1, 4-hexadiene, dicyclopentadiene, bicyclo (2, 2, l)hepta-2 , 5-diene, commonly known as norbornadiene, as well as the alkenyl norbornenes wherein the alkenyl group contains 1 to 20 carbon atoms and preferably 1 to 12 carbon atoms . Examples of some of the latter compounds includes 5-methylene-2-norbornene, 5-ethylidene-2-norbornene, vinyl norbornene as well as alkyl norbornadienes .

As known to those skilled in the art, it is also possible to include with certain Ziegler-Natta catalyst systems, as a comonomer in the polymerization of the polyolefin prearm, a small amount, typically up to 10 percent, of a functional ethylenically unsatura- ted monomer. Such monomers typically contain 2 to 20 carbon atoms and contain an ethylenically unsaturated group. Preferred functional ethylenically unsaturated monomers include acrylate and methacrylate esters wherein the ester group is Cj_. to C₂₀ alkyl or C₆ to C₂₅ aryl including substituted aryl, vinyl amines, vinyl- cyano compounds and vinyl esters. Representative of suitable functional monomers which can be used in the practice of the present invention include methylmeth- acrylate, methylacrylate, N-vinylamine, N-vinylpyri- dine, acrylonitrile, vinylacetate, etc.

In a particular practice of the present invention, the polyolefin prearm is produced using metallocene catalysts. As used herein, the term "metallocene catalyst system" refers to and includes the use of a transition metal compound comprising a metal from Groups 3 to 6 of the Periodic Table such as titanium, zirconium, chromium, hafnium, yttrium containing at least one coordinating ligand that is a highly conjugated organic compound (e.g., cyclopenta- dienyl or indenyl) . Such catalyst systems are themselves known and are described in the following published applications, the disclosures of which are incorporated herein by reference: EP-A-69, 951; EP-A-347,129; ; EP-A-468 , 537 ; EP-A-500 , 944 ; WO 94/11406 and WO 96/13529. Also the process as disclosed in WO 96/23010 is suitable. In addition, other Ziegler catalyst systems likewise known in the art as producing terminal unsaturation can likewise be used in the practice of this invention, as well as the Cr-based

Phillips catalyst systems. One such example is titanium chloride supported on magnesium chloride and used in high temperature (above 100°C) polymerization systems. Another example is the copolymerization of ethylene with higher 1-alkenes using V0C1₃ and diethylaluminum chloride. In general, the choice of catalyst system and polymerization conditions will depend on the specific type of polyolefin prearm desired, as known to those skilled in the art of Ziegler-Natta polymerization technology. Thus, the composition of the arms are dependent on the limits of Ziegler-Natta polymerization technology and can be controlled independent of the composition of the backbone.

In addition to the foregoing polyolefins, the concepts of the present invention also may employ polyolefins derived from conjugated dienes which contain ethylenic unsaturation. Such polyolefins can be described as homopolymers of conjugated dienes containing 4-8 carbon atoms (such as butadiene, isoprene and chloroprene) , and copolymers of those monomers with one or more vinyl monomers copolymerizable therewith. Included also as the polyolefin prearms which can be reacted in accordance with the concepts of the present invention are polybutadiene polymers . Because the concepts of the present invention make it possible to introduce in a controlling fashion large numbers of polyolefin arms, the properties of the polyolefin arms linked to the polymeric backbone dominate the properties of the resulting branched polymer. Thus, the molecular weight of the polyolefin prearms can be varied to control the properties desired in the overall branched polymer. Similarly, the method of preparation of the prearms can be used to, in part, control over the properties of the arms. In general, the lengths of the arms, expressed as the number-average molecular weight, M_n, can be varied within broad limits, depending on the properties desired. As a general rule, use is made of polymer prearms having a M_n between 300 and 2,000,000 g/mol, and preferably between 600 and 500,000 g/mol.

It is generally preferred that the molecular weight distribution (MWD) , referring to the ratio between the weight-average molecular weight (M_w) and the number-average molecular weight (M_n) as determined by size exclusion chromatograph-differential viscometry (SEC-DV) , of the arms be relatively narrow, that is in the range of at least 1.2 ranging up to 3.5 to improve efficiency of the coupling reaction. However, broader MWD polyolefin prearms can be used and are often desired in the practice of this invention. As will be appreciated by those skilled in the art, as the molecular weight of the polyolefin prearm to be coupled with the backbone increases in molecular weight, the number of double bonds in the polyolefin prearm decreases on a weight basis . That in turn results in a reduction of the coupling efficiency generally expressed as the percent of polyolefin prearms actually bonded to the polymeric backbone . The number of repeating units with Si-H functionality capable of being coupled to a plurality of polyolefin prearms depends, to some degree, also on the intended application of the polymer. As a general rule, it is preferred that the hydrosilane-containing polymeric backbone contains at least 4 functional Si-H groups through which polyolefin arms can be linked to form a branched structure. In the preferred practice of the invention, it is often desirable to employ a reactive polymeric backbone having the capability of forming at least 3 to 300 polyolefin arms linked to the polymeric backbone . One suitable class of polymeric backbones used in the practice of the present invention are polyhydrosilane polymers and copolymers containing a large number of repeating units containing a silicon-hydrogen bond. In general, it is preferred to use silicon-containing polymers having repeating units of the general formula: H

X S i

R wherein X is a group containing a heteroatom, such as 0, P, S, N, Si and/or one or more carbon atoms either as part of an aliphatic or aromatic group, and R is hydrogen or an organic group, and preferably hydrogen, alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy.

Illustrative are polyhydrosiloxanes derived from an alkylhydrosiloxane end-capped with either a hydrosilane functionality or an alkylsilane functionality. Such siloxanes have the general formula:

wherein R_x to R₇ is each independently hydrogen or an organic group; preferably, R_x, R₂ and R₃ can be either hydrogen, alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy; R₄ is hydrogen, alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy; R₅ and R₆ are alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy and R₇ is hydrogen, alkyl, aryl, cycloalkyl, alkoxy, aryloxy or cycloalkoxy; n is an integer having a minimum value of 4, preferably of 10 and more preferably 25 or higher. Such polyhydrosiloxanes, as is well-known to those skilled in the art, are commonly available from a number of companies including Dow Corning and Rhone Poulenc .

As will also be appreciated by those skilled in the art, it is also possible to use, as the reactive polymeric bacbone, siloxane copolymers containing 10 or more and typically 10 to 80 silicon-hydrogen groups as repeating units. As will also be appreciated by those skilled in the art, it is likewise possible to employ in place of the polyhydrosiloxanes described above, the corresponding analogs thereof in which the oxygen atom is at least partially replaced by sulfur or nitrogen atoms. Representative of suitable polyhydrosilane polymers are polymethylhydrosilane, polymethylhydro- siloxane, methylhydrodimethyl-siloxane copolymer, methylhydrophenylmethylsiloxane copolymer, methyl- hydrocyanopropylsiloxane copolymer, methylhydromethyl- octylsiloxane copolymer, poly (1, 2-dimethylsilazane) , (1-methylsilazane) (1, 2-dimethylsilazane) copolymer and methylhydrocyclosiloxane polymer. In general, use is made of silicon-containing polymer backbone having a number average molecular weight of 300 or higher, and preferably 300 to 10,000.

As is well known to those skilled in the art, the reaction between the polyolefin prearm and the silicon-containing polymeric backbone is carried out under conditions of heat and a suitable catalyst to effect addition of the silicon hydride across the terminal unsaturation of the polyolefin prearm to link the arm to the silicon-containing polymeric backbone. Suitable hydrosilation catalysts to effect that reaction are known in the art and contain metals from Groups 8 to 10 of the Periodic Table of the Elements. Such catalysts are described in Lukevics et al . in J. Organomet . Chem. Lib. 1977, 5, pages 1-80 and include compounds based on palladium, platinum, nickel, rhodium and cobalt. Hydrosilation catalysts which have been found to be particularly effective are

H₂PtCl₆- xH₂0 (x≥0) , K .Pt (C₂H₄ ) C1₃] , RhCl ( PPh₃ ) ₃ or Co₂ (CO) ₈ . Such catalysts and their use are also described in the literature and in U . S . Patent Nos . 5 , 486 , 637 ,

4,578,497, 3,220,972, and 2,823,218, the disclosures of which are incorporated herein by reference.

The hydrosilation catalyst may be dissolved in a suitable solvent to facilitate handling and measuring of the small amounts of metal catalyst usually employed. Suitable solvents include aromatic hydrocarbons (such as benzene, toluene, xylene) and/or polar solvents (such as alcohols, ketones, glycols and esters) . While the hydrosilation catalyst can be handled in suitable solvents, storage in those solvents, particularly at temperatures above ambient, results in deactivation of the metal catalyst.

In the practice of the invention, it is often desirable and preferable to carry out the reaction in the presence of a halogenated organic compound as an accelerator for the reaction. As a general rule, compounds suitable for use as accelerators have the general formula :

D_4-„ C X_n wherein X is a halogen atom, and preferably chlorine and bromine; D is a substituent which is hydrogen, halogen as described above, a halogenated alkyl, alkenyl, aryl, aralkyl or cycloalkyl group or a carboxy, carbonyl, oxycarbonyl or alkoxy containing group; and n is an integer from 1-4. In the preferred practice of the invention, the accelerators have the general formula:

X

I I A C —— Z

I

Y

wherein A is a phenyl group which may contain 1 or 2 halogen atoms or alkyl groups substituted thereon, or a thienyl, furyl pyrollyl, N-alkyl pyrollyl or a pyridyl group. Those groups are either bonded directly to the carbon atom or indirectly through a carbonyl group . In addition, A can be a phenyl or benzyl group substituted with 1 or 2 nitro groups . X is halogen and preferably chlorine or bromine and Y is halogen as described above, hydrogen or a _λ to C₈ hydrocarbon group. Z is selected from any one of the following in which R' and R" are a hydrogen atom or a carbon group containing 1-8 carbon atoms :

0 0

II II

— C ≡ N — C — OH — C R '

0 0 0

II II

— C — O — (CH₂ ) _ra — OR ' — C X OR '

0 0

or

0 0

II II X — C — (CH₂ ) _p — C — X

m is 1-8 and p is 0-8. Preferred accelerators are those having the structure : Cl 0

:o>- C - OH

I

H

The amount of accelerator employed in the practice of this invention depends on the quantity of hydrosilation catalyst employed and is generally ratioed in terms of moles of accelerator to moles of metal component in the hydrosilation catalyst. For reactions at 80 to 350 °C, generally it is convenient to employ molar ratios of accelerator to metal component of 0.01/1 to 100/1. When the accelerator is used in the practice of this invention, it is preferred to prepare, in a suitable solvent, a stock solution of the metal catalyst component and the accelerator for addition to the reaction vessel. It has been found that storage of the accelerator and catalyst in aromatic hydrocarbon solvents or aliphatic alcohol even at temperatures above ambient does not result in deactivation of the catalyst. Suitable solvents for preparation of the stock solution are aliphatic alcohols, aromatic alcohols, aliphatic ketones, esters or glycols.

In accordance with one of the concepts of the invention, it has been found that the reaction between the polyolefin prearms and the hydrosilane-containing polymeric backbone can be carried out with far greater efficiency and shorter reaction times as compared to the prior art when the reaction is carried out as a bulk reaction and/or in the presence of the accelerator. As used herein, the term "bulk reaction" refers to a process in which the solid or liquid polyolefin prearms are reacted with the hydrosilane-containing polymer backbone in the presence of a minimum amount of solvent. It has been found that the reaction rate can be increased markedly when the concentration of polyolefin prearm in any solvent is at least 50%, and preferably at least 75%. Indeed, it has been found that no solvent need be employed at all. For example, the reaction between the polyolefin prearms and the hydrosilane-containing polymeric backbone can be carried out in a batch or continuous high intensity mixing device such as various types of melt processing equipment including a Haake mixer, Banbury mixer, Brabender plasticord, an extruder or like blending equipment with little to no solvent employed. Where a solvent is used, the solvent can be a solvent for the polyolefin prearm such as aliphatic hydrocarbons (including pentane, hexane, heptane, pentamethylheptane or distillation fractions) ; aromatic hydrocarbons (such as benzene or toluene) ; halogenated derivatives of aliphatic or aromatic hydrocarbons (such as tetrachloroethylene) , or ethers (such as tetrahydrofuran or dioxane) . Surprisingly, it has been found that both reaction with and without the accelerator, regardless of the presence of solvent, are significantly enhanced as to reaction rate and coupling efficiency when the catalyst solution or the catalyst/accelerator solution is dosed to a mixture of polyolefin prearms and polyhydrosilane backbone at elevated temperatures, 80 to 350 °C, and preferably 120 to 300 °C

The relative proportions of the polyolefin prearm and the polyhydrosilane are controlled to ensure that the desired number of polyolefin prearms become linked by the addition reaction to the polymeric backbone. The reactants are ratioed according to the moles of terminal unsaturation (C=C) in the polyolefin prearm to the moles of Si-H bonds in the polyhydrosilane. In general, mole ratios ranging from 1:100 to 10:1 are employed.

The reaction temperature employed in the bulk reaction, since little or no solvent is employed, is generally higher than that frequently used in dilute solution reactions or prior art addition reactions of this type. The use of generally higher temperatures is yet another factor which promotes the efficiency in the reaction. As a general rule, temperatures ranging from about 100 to 350 °C can be used, and preferably 120 to 300 °C. Similarly, the reaction time afforded by the process of the present invention is generally less than that required in prior processes. Depending somewhat on the nature of the hydrosilane-containing backbone and the polyolefin prearms reacted with it, reaction times are generally less than 10 hours, and preferably less than 4 hours. In accordance with the preferred embodiment of the invention, the reaction time can be controlled within the range of 10 seconds to 240 minutes and preferably 10 seconds to 60 minutes.

Having described the basic concepts of the invention, references are now made to the following examples which are provided by way of illustration, and not by way of limitation, of the practice of the invention.

Polyolefin prearms and reagents used in carrying out the examples are described below and in

Table I: Table I: Polyolefin Prearms

(a) A, B, C, E, F, G and I are ethylene/propylene copolymers prepared by solution polymerization with a metallocene type catalyst; D is Stamylan 7625 (registered trademark of DSM N.V. , the Netherlands) ; H is a low density polyethylene with a density of .966 g/cm³. (b) The polyolefin molecular weights were determined with Size Exclusion Chromatography-Differential Viscometry (SEC-DV) at 150 °C using 1, 2 , 4-trichloro- benzene as solvent. A Waters M 150 °C GPC with DRI-detector and a Viscotek Differential Viscometer (DV) Model 100-02, the detectors connected in parallel, was used with Toyo Soda (TSK) GMHXL-HT, mixed bed (4X) columns (plate count of 25000 as determined on n-C₂₈H₅₈) . The SEC-DV technique was used to calculate the number average molecular weight (M_n) in units of kg/mole, the weight average molecular weight (M_w) in units of kg/mole, and the molecular weight distribution (MWD=M_W/M_n) using a universal calibration curve based on polyethylene as standards . The number of arms on the branched polyolefin polymers was defined as the ratio of the molecular weight at the top of the SEC-DV chromatogram of the branched polymer to the molecular weight at the top of the SEC-DV chromatogram of the original polyolefin prearm (the polyolefin before the coupling reaction) . Therefore, the number of arms as defined herein was the mean number of arms on the backbone for that experiment. The coupling efficiency was determined from the SEC-DV chromatograms as the ratio of the molar mass distribution calculated for the branched polyolefin (in some cases after correction for residual prearm) to the molar mass distribution calculated for the polyolefin prearms, using curve fitting techniques known in the art for measuring molar mass distribution.

(c) The type and degree of terminal unsaturation (TU) was determined by Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR) and are reported as groups per 100,000 carbon atoms. Calculations were based on standard published procedures routinely practiced by those skilled in the art. VI represents the number of vinyl end groups, Vld represents the number of vinylidene end groups. (d) The ethylene content (C₂) , reported as mole percent of the total monomers polymerized, was determined by means of Fourier Transform Infrared Spectroscopy with calculations based on standard published procedures routinely practiced by those skilled in the art. Reagents used were as follows: PMHS = polymethylhydrosiloxane, containing an average of 48 Si-H groups per molecule CPS = copolyhydrosiloxane containing 14 Si-H groups per molecule (copolymer of dimethyl and methylhydrosilanes)

PMH = pentamethylheptane HPCH = H₂PtCl₆.6H₂0

DCPAE = dichlorophenylacetic acid ethylester MCDPAE = monochlorodiphenylacetic acid ethyl ester IPA = isopropylalcohol

SNO130 = a paraffinic petroleum oil

Comparative Experiment A

Polymer I, 10 gmε, dissolved in 100 ml PMH was mixed with HPCH dissolved in tetrahydrofuran at a molar ratio of 1000/1. The PMHS was added to the reaction solution so that the molar ratio of Si-H to C=C in Polymer I was 5/1. The reaction mixture was stirred at 140 °C for 14 days. The branched polyolefin collected after evaporation of the solvent mixture at 80 °C under vacuum was analyzed by SEC-DV to contain 5 arms .

Comparative Experiment B The procedure of Comparative Experiment A was repeated except that the reaction mixture was stirred at 90 °C for 3 days. The recovered branched polyolefin was analyzed by SEC-DV to contain 4 arms. The coupling efficiency was 85%.

The following Examples I-IX demonstrate the use of an accelerator. In each case, the accelerator and Pt catalyst were predissolved in IPA and charged as a stock solution. Example I - Coupling Polymer A at 10 wt% Solution

Polymer A, 10 gms, was dissolved in 100 ml of toluene in an agitated flask. PMHS was added to the polymer solution to provide a molar ratio of Si-H to C=C in Polymer A of 5/1. The reaction mixture was subsequently heated to 130 °C after which the HPCH catalyst and the DCPAE accelerator were added dissolved in IPA to provide a molar ratio of Pt in the catalyst to C=C in Polymer A of 1/1000 and DCPAE to Pt of 10/1. This reaction mixture was agitated at 130 °C for 24 hours, then blocked with an excess of 1-decene. The branched polyolefin was recovered after evaporation of the solvent under vacuum at 80 °C and was analyzed by SEC-DV to contain 3 arms. The coupling efficiency was 82%.

Example II- Coupling of Polymer F at 10 wt% Solution

Polymer F was dissolved in PMH at a concentration of 10 wt%. PMHS was added to the polyolefin solution to provide a molar ratio of Si-H to C=C in Polymer F of 5/1. The reaction solution was subsequently heated to 130 °C after which an IPA solution of HPCH catalyst and MCDPAE accelerator at a molar ratio of MCDPAE to Pt of 10/1 was charged to provide molar ratio of Pt in the catalyst to C=C in

Polymer F of 1/1000. This reaction mixture was stirred at 130 °C for an additional 40 minutes, then blocked with an excess of 1-decene. The branched polyolefin was recovered after evaporation of the solvent under vacuum at 80 °C and was analyzed by SEC-DV to contain 3 arms. The coupling efficiency was 88%.

The following Examples III-IX were carried out in bulk, that is, as concentrated solutions or in the melt with an accelerator in the form of DCPAE. Example III - Coupling of Polymer C as a 50 wt% Solution in PMH

Polymer C, 70 gms, was dissolved in 100 ml of PMH. PMHS was added to the polymer solution to provide a molar ratio of Si-H to C=C in Polymer C of 5/1. The reaction mixture was subsequently heated to 130 °C and a solution of HPCH and DCPAE in IPA (molar ratio of DCPAE to Pt was 10/1) was added to provide a molar ratio of Pt in the catalyst to C=C in the polymer of 1/1000. The reaction mixture was stirred maintaining

130 °C for an additional 15 minutes. Then, the reaction was blocked with an excess of 1-decene. The branched polyolefin was recovered by evaporation of the solvent under vacuum at 80 °C and was analyzed by SEC-DV to contain 4 arms. The coupling efficiency was 93%.

Example IV - Coupling of Polymer F in Oil

Polymer F was dissolved in SNO-130 oil with PMHS and reacted according to the procedure of Example III. After addition of the catalyst at 130 °C, the reaction mixture was stirred an additional 20 minutes before blocking. Analysis of the oil solution by SEC-DV showed a polymer with M_w of 210 kg/mol . The coupling efficiency was 83%.

Example V - Coupling of Polymer C as a 75 wt% Solution in PMH

The procedure of Example III was repeated with the following exceptions: 40 gms of Polymer C were dissolved in 20 ml of PMH, the reaction mixture was heated to 150 °C prior to addition of the catalyst and accelerator. The molar ratio of DCPAE to Pt in the HPCH was 16. After addition of the DCPAE and HPCH solutions, the reaction mixture was stirred for an additional 5 minutes at 150 °C, then blocked with an excess of 1-decene. The branched polymer recovered after evaporation of the PMH under vacuum at 80 °C was analyzed by SEC-DV to contain 5 arms. The coupling efficiency was 96%.

Example VI - Coupling of Polymer E as a 95 wt% Mixture in PMH

Polymer E, 40 gms (stabilized with a phenolic antioxidant) , was heated with PMHS at a molar ratio of Si-H to C=C in Polymer E of 5/1 and 3 ml of PMH at 150 °C in a Haake Rheomix600 batch mixer. When the temperature was stabilized at 150 °C, an IPA solution of HPCH and DCPAE (molar ratio of DCPAE to Pt in the HPCH was 10/1) were charged to provide a ratio of Pt to C=C in Polymer E of 1/1000. This mixture was heated and agitated at 150 °C for 5.5 minutes, then blocked with an excess of 1-decene. The branched polymer was analyzed by SEC-DV to contain 5 arms. The coupling efficiency was 90%.

Example VII - Coupling of Polymer B in the Melt

Polymer B, 10 gms, was heated and agitated in a flask like Example 1, but without solvent to 130 °C. PMHS was added to the molten Polymer B to provide a molar ratio of Si-H to C=C in Polymer B of 5/1, followed immediately by a solution of HPCH and DCPAE (molar ratio of DCPAE to Pt of 1) to provide a molar ratio of Pt to C=C in Polymer B of 1/1000. This mixture was stirred, maintaining 130 °C for 45 minutes. The reaction was blocked with an excess 1-decene. The branched polymer recovered from the reactor was analyzed by SEC-DV and contained 5 arms. The coupling efficiency was 86%.

Example VIII - Coupling of Polymer A in the Melt Polymer A, 40 gms, stabilized with a phenolic antioxidant, was heated and agitated with PMHS in a Haake mixer to 150 °C according to the procedure of Example VI with the following exceptions: No PMH was added; the solution of HPCH and DCPAE was adjusted so that the molar ratio of DCPAE to Pt in the HPCH was 16. The reaction mixture was stirred at 150 °C for an additional 15 minutes before blocking. The recovered branched polymer was analyzed by SEC-DV to contain 4 arms. The coupling efficiency was 96%.

Example IX - Coupling of Polymer D in an extruder Polymer D (melt index of 0.97 dg/min. @ 190 °C, 15) was treated with an IPA solution of PMHS in a Diosna mixing unit to provide a mixture containing 0.1 wt% PMHS in Polymer D. This mixture was fed to a ZSK 30 mn/42F extruder at a speed of 4 kg/hr, simultaneously with an IPA solution of HPCH and DCPAE (4.3 mol/1 HPCH in IPA with a DCPAE to Pt ratio of 10/1) fed at 5 ml/min through a liquid injection port. The temperature in the extruder was maintained at 180 °C and the screw speed was 100 rpm. The branched polymer leaving the extruder was analyzed to have a melt index (190°C, 15) of 0.41 dg/min. and by SEC-DV to contain 4 arms.

Examples X to XIV

The following Examples were carried out in bulk, that is, as a concentrated solution or in the melt without the addition of an accelerator. In each case, the HPCH in IPA solution was dosed to the mixture of reactants at elevated temperatures.

Example X - Coupling of Polymer A in Melt

Polymer A and PMHS were heated and agitated in a Haake mixer at 150 °C according to the procedure of Example VIII with the following exceptions: the

HPCH/IPA solution was added at a temperature of 150 °C so that the molar ratio of C=C in Polymer A to Pt was 1000/1, no DCPAE was used. The mixture was agitated at 150 °C for 6 minutes before blocking with decene. The recovered branched polyolefin was analyzed by SEC-DV to have a M_w of 720 kg/mol and to contain 7 arms. The coupling efficiency was 93%.

Example XI - Coupling of Polymer C at 50 wt% Solution The procedure of Example III was repeated with Polymer C and PMHS with the exception that no

DCPAE accelerator was added. The HPCH in IPA was dosed to the reaction solution at 130 °C and the temperature held for 60 minutes before blocking. The branched polyolefin recovered by evaporation of the solvent under vacuum at 80 °C was analyzed by SEC-DV to have 4 arms and a M_w of 225 kg/mol. The coupling efficiency was 96%.

Example XII - Coupling of Polymer A at 10 wt% Solution The procedure of Example I was repeated with

Polymer A and PMHS with the exception that no DCPAE was added. The reaction mixture was heated to 90 °C and then the HPCH in IPA was charged to the reaction flask.

The temperature was maintained at 90°C with agitation for 23 hours, then the reaction was blocked. The branched polyolefin recovered after evaporation of the solvent was analyzed by SEC-DV to contain 3 arms and to have a M_w of 180 kg/mol. The coupling efficiency was

80%.

Example XIII - Coupling of Polymer G as a 50 wt%

Solution

The procedure of Example III was followed with Polymer G and CPS in PMH with the following exceptions: the molar ratio of Si-H in CPS to C=C in

Polymer G was l/l, the reaction temperature was 150 °C, and no DCPAE was used. The reaction mixture was maintained at 150 °C after charging the HPCH/IPA solution for 60 minutes before blocking. The branched polyolefin recovered from the reaction was analyzed by SEC-DV to have 6 arms. The coupling efficiency was 65%.

Example XIV A - Coupling of Polymer H in Melt

The procedure of Example VIII was followed with Polymer H (a low density polyethylene, density = .966 gr/cm³) and PMHS with the following exceptions: the molar ratio of Si-H in the PMHS to C=C in Polymer H was 2.5/1, and no DCPAE was used. The reaction mixture was maintained at 150 °C with agitation for 3 minutes after charging the HPCH/IPA at 150 °C. The coupling efficiency was 100%. The branched polyolefin was analyzed by SEC-DV to have a M_w of 160 kg/mole and was a mixture of branched and linear polyethylene because only 40% of Polymer H molecules had terminal ethylenic unsaturation.

Example XIVB - Coupling of Polymer H at 70 wt%

The procedure of Example V was repeated with Polymer H and PMHS with the following exceptions: polymer H was dissolved in PMH at a concentration of 70 wt%, the molar ratio of Si-H in the PMHS to C=C in polymer H was 2.5/1 and no DCPAE was charged. The reaction mixture was heated at 150 °C for 3 minutes after charging the HPCH/IPA at 150 °C. The coupling efficiency was 73%. The mixture of branched polyolefin and linear polyolefin had a M_w of 97 kg/mole.

Claims

C L A I M S

1. A method for carrying out the reaction between a polyhydrosilane and polyolefin prearms to produce a branched polyolefin in the form of a comb, star, nanogel and structural combinations thereof comprising the steps of :

(a) combining polyolefin prearms having ethylenic unsaturation with a polyhydrosilane selected from the group consisting of homopolymers and copolymers of a hydrosilane to form a reaction mixture;

(b) heating the reaction mixture to an elevated temperature sufficient to promote hydrosilation;

(c) dosing a hydrosilation catalyst to the reaction mixture at the elevated temperature;

(d) maintaining the reaction mixture at a temperature and for a time sufficient to promote the addition of the Si-H groups of the polyhydrosilation across the ethylenic unsaturation of a polyolefin prearm; and

(e) recovering the branched polyolefin thus produced.

2. A method according to claim 1 wherein the polyolefin prearm contains terminal unsaturation in the form of vinyl, vinylidene, vinylene groups and mixtures thereof .

3. A method according to claim 1 wherein the polyolefin prearm is a polyethylene polymer having terminal unsaturation.

4. A method according to claim 1 wherein the polyolefin prearm is a polypropylene polymer having terminal unsaturation.

5. A method according to claim 1 wherein the polyolefin prearm is an interpolymer of ethylene, propylene and at least one polyene monomer containing two or more carbon-to-carbon double bonds and 4 to 28 carbon atoms.

6. A method according to claim 1 wherein the polyolefin prearm is a copolymer of ethylene and at least one alpha-olefin, said copolymer having terminal unsaturation.

7. A method according to claim 1 wherein the reaction is carried out in the absence of a solvent .

8. A method according to claim 1 wherein the reaction is carried out in the presence of a solvent at a concentration of the polyolefin prearm in the solvent of at least 50% by weight.

9. A method according to claim 1 wherein the reaction is carried out in an extruder.

10. A method according to claim 1 wherein the hydrosilation catalyst comprises a metal from Groups 8 to 10 of the Periodic Table.

11. A method according to claim 10 wherein the metal is platinum.

12. A method according to claim 1 wherein the catalyst is chloroplatinic acid.

13. A method according to claim 1 wherein the reaction is carried out as a bulk reaction.

14. A method according to claim 1 wherein the reac tion is carried out in the presence of an accelerator.

15. A method according to claim 14 wherein the accelerator is a halogenated organic compound.

16. A method according to claim 14 wherein the accelerator is combined with the hydrosilation catalyst for dosing to the reaction mixture.

17. A method according to claim 1 wherein the reaction is carried out in the presence of an accelerator selected from the group consisting of trichloroacetic acid esters, dichlorophenylaceticacidethylesters, monochlorodiphenylacetic acid ethyl esters, hexachloraoacetone, hexachloropropylene, trichloraltoluene, and perchlorocrotonic acid esters.

18. A method according to claim 1 wherein the polyhydrosilane is selected from the group consisting of polyhydrosilane polymers and copolymers containing repeating units of the general formula:

H X si

R

wherein X is a group containing a heteroatom and/or one or more carbon atoms as part of an aliphatic or aromatic group and R is hydrogen or an organic group .

19. A method according to claim 16 wherein the polyhydrosilane has a number average molecular weight of 300 or higher.

20. A method according to claim 1 wherein the mixture of the polyolefin prearm and the polyhydrosilane is heated to a temperature within the range of 80┬░ to 350┬░C.

21. A method for carrying out the reaction between a polyhydrosilane and polyolefin prearms to produce a branched polyolefin in the form of a comb, star, nanogel and structural combinations thereof comprising the steps of:

(a) reacting in a bulk reaction polyolefin prearms having ethylenic unsaturation with a polyhydrosilane selected from the group consisting of homopolymers and copolymers of a hydrosilane in the presence of a hydrosilation catalyst and an accelerator at temperature to promote the addition of the H-Si group across the ethylenic unsaturation of the polyolefin; and (b) recovering the branched polyolefin thus produced.

22. A method according to claim 21 wherein the olyolefin prearm is a polyethylene polymer having terminal unsaturation.

23. A method according to claim 21 wherein the polyolefin prearm is an interpolymer of ethylene, propylene and at least one polyene monomer containing two or more carbon-to-carbon double bonds and 4 to 28 carbon atoms.

24. A method according to claim 21 wherein the polyolefin prearm is a copolymer of ethylene and at least one alpha-olefin, said copolymer having terminal unsaturation.

25. A method according to claim 21 wherein the reaction is carried out in the absence of a solvent .

26. A method according to claim 21 wherein the reaction is carried out in an extruder.

27. A method according to claim 21 wherein the catalyst is chloroplatinic acid.

28. A method according to claim 21 wherein the accelerator is a halogenated organic compound.

29. A method according to claim 21 wherein the accelerator is a compound having the general formula:

X.

wherein X is a halogen atoms, D is selected from the group consisting of hydrogen, halogen, halogenated alkyl alkenol, aryl, aralkyl or cycloalkyl group, a carboxy carbonyl, oxycarbonyl or alkoxy group and n is an integer from 1 to 4.

30. A method according to claim 14 wherein the accelerator is a compound having the general formula :

XΓÇ₧

wherein X is one or more halogen atoms, D is selected from the group consisting of hydrogen, halogen, halogenated alkyl alkenol, aryl, aralkyl or cycloalkyl group, a carboxy carbonyl, oxycarbonyl or alkoxy group and n is an integer from 1 to 4.

31. A method for carrying out the reaction between a polyhydrosilane and polyolefin prearms to produce a branched polyolefin in the form of a comb, star, nanogel and structural combinations thereof comprising the steps of: (a) reacting polyolefin prearms having ethylenic unsaturation with a polyhydrosilane selected from the group consisting of homopolymers and copolymers of a hydrosilane in the presence of a catalyst and a halogenated organic compound accelerator at a time and temperature sufficient to promote the addition of an H-Si group across the ethylenic unsaturation of the polyolefin prearm; and (b) recovering the branched polyolefin thus produced.

32. A method according to claim 31 wherein the polyhydrosilane and the polyolefin prearms are dissolved in a solvent .