WO2005063376A1

WO2005063376A1 - Process for making peroxide-containing olefin polymers

Info

Publication number: WO2005063376A1
Application number: PCT/IB2004/003738
Authority: WO
Inventors: Cheng Q. Song
Original assignee: Basell Poliolefine Italia, s.r.l.
Priority date: 2003-12-22
Filing date: 2004-11-12
Publication date: 2005-07-14
Also published as: TW200534923A

Abstract

A process for making a peroxide-containing olefin polymer in a two-zone reactor with a first and a second interconnected reaction zones, into which particles of an olefin polymer and an organic peroxide are fed and from which the peroxide-containing olefin polymer is discharged, comprises: feeding into a two-zone reactor an olefin polymer and an organic peroxide, thereby forming an olefin polymer mixture comprising: about 90.0 to about 99.9 wt% of an olefin polymer material; about 0.1 to about 10.0 wt% of an organic peroxide; wherein the sum of components I + II is equal to 100 wt%; wherein the olefin polymer mixture is exposed to a controlled amount of oxygen greater than 0.004% by volume of oxygen in gas phase at a temperature at least 25°C but below the softening point of the polymer, thereby producing a peroxide-containing olefin polymer.

Description

PROCESS FOR MAKING PEROXIDE-CONTAINING OLEFIN POLYMERS This invention relates to a process for making polyolefins containing peroxide functionalities in the presence of an organic peroxide and a controlled amount of oxygen. Reactive polyolefins with peroxide functionality have been of interest in the art because the peroxide functional groups attached to the polyolefm backbone can be used to initiate various chemical reactions, such as, grafting polymerizations. U.S. Pat. No. 5,817,707 discloses grafting polymerization using reactive polyolefins prepared by an electron beam irradiation process. The process includes irradiating a particulate polypropylene material in a substantially inert atmosphere, exposing the irradiated propylene polymer material to a controlled amount of oxygen, and heating the polymer material to a specified temperature for a specified time. The resulting polymer may be used for initiating graft polymerization reactions between the olefin polymer and vinyl monomers. Organic peroxides have also been used in the graft polymerization of polyolefins with vinyl monomers. U.S. Pat. No. 4,990,558 discloses a process for making grafted polymer. The grafting sites were produced by treatment with an organic peroxide which is a free-radical polymerization initiator. The free radicals produced in the polymer as a result of the chemical decomposition form the active grafting sites on the polymer and initiate the graft polymerization of the vinyl monomer at these sites. But the active grafting sites so generated have very short half-life time and the intermediates containing such active grafting sites may not be separated from the reaction system. It is well known that the organic peroxides can initiate homopolymerization of vinyl monomers; therefore, the ratio of graft polymerization versus the homopolymerization is relatively low. In addition, because the organic peroxide has excellent mobility in the reaction system, besides the graft polymerization or homopolymerization in the bulk, it will initiate the polymerization in undesired locations, such as on the reactor walls, to result in reactor fouling during polymerization. U.S. Patent Application Serial No. 10/305,816 disclosed a method to prepare an oxidized olefin polymer material by treating the polymer material with an organic peroxide in the presence of a controlled amount of oxygen. Since the oxidation reaction is exothermic the normal autoclave type reactor could not remove the heat effectively, thus causing an increase in the polymer temperature to its softening point and generating undesirable polymer clumps. A gas phase process for producing olefin polymer graft copolymers, including providing a reaction apparatus having first and second reaction zones operatively connected to each other is disclosed in U.S. Patent No. 5,696,203. A graft copolymer is prepared by mixing an olefin polymer and a free-radical polymerizable monomer in the gas phase process while maintaining free-radical polymerization conditions and a substantial non-oxidizing environment in reaction zones. There is no indication that a reaction could be carried out in an oxidizing environment and in the absence of a free-radical polymerizable monomer. Therefore, there is a need to prepare free flowing peroxide-containing olefin polymers which are reactive in initiating graft polymerization and other reactions known to persons skilled in the art, without using an expensive irradiation source. The applicant has unexpectedly found that a free flowing peroxide-containing olefin polymer can be prepared in the presence of an organic peroxide and a controlled amount of oxygen in a particular reactor, comprising a first and a second interconnected reaction zones through which the polymer circulates under different flow modes, without causing usual difficulties such as polymer clumping, reactor fouling etc. The present invention provides a process for making a peroxide-containing olefin polymer carried out in a two-zone reactor with a first and a second interconnected reaction zones, into which particles of an olefin polymer and an organic peroxide are fed and from which the peroxide-containing olefin polymer is discharged. Said process comprises: feeding into a two-zone reactor an olefin polymer and an organic peroxide, thereby forming an olefin polymer mixture comprising: I. about 90.0 to about 99.9 wt%, preferably about 95.0 to about 99.8, most preferably about 98.0 to 99.5, of an olefin polymer material; II. about 0.1 to about 10.0 wt%, preferably about 0.2 to 5.0, most preferably about 0.5 to 2.0, of an organic peroxide; wherein the sum of components I + II is equal to 100 wt%; wherein the olefin polymer mixture is exposed to a controlled amount of oxygen greater than 0.004% by volume, preferably about 0.1 to 6% by volume, most preferably about 0.2 to 4% by volume of oxygen in gas phase, at a temperature of at least 25 °C but below the softening point of the polymer, preferably at about 80°C to 140°C, thereby producing a peroxide-containing olefin polymer; wherein the two-zone reactor comprises a first interconnected reaction zone through which the polymer mixture flows under fast fluidization conditions, leaves said first reaction zone and enters a second interconnected reaction zone through which the polymer mixture moves in a plug flow mode by gravity, leaves said second reaction zone and is reintroduced into said first reaction zone, thus establishing a circulation of the olefin polymer between the two reaction zones. According to another embodiment of the invention, before discharging from the two- zone reactor, the peroxide-containing olefin polymer is treated at a temperature of at least 80°C but below the softening point of the polymer, in an inert atmosphere, with an oxygen concentration of 0.004% by volume or less by removing the oxygen from the reactor. According to another embodiment of the invention, after discharging from the two- zone reactor, the peroxide-containing olefin polymer is treated at a temperature of at least 80°C but below the softening point of the polymer, in an inert atmosphere, with an oxygen concentration of 0.004% by volume or less in a second reactor. According to another embodiment of the invention, before discharging from the two- zone reactor, the peroxide-containing olefin polymer is contacted with at least one polymerizable vinyl monomer, at a temperature from at least about 50°C to below the softening point of the polymer, by feeding the polymerizable vinyl monomer into the two- zone reactor. According to another embodiment of the invention, after discharging from the two- zone reactor, the peroxide-containing olefin polymer is contacted with at least one polymerizable vinyl monomer at a temperature from at least about 50°C to below the softening point of the polymer in a second reactor. Olefin polymer materials suitable for making the peroxide-containing olefin polymer materials include propylene, ethylene, and butene-1 polymer materials. When a propylene polymer material is used as the starting material for making the peroxide-containing olefin polymer materials, the propylene polymer is preferably selected from: (a) a crystalline homopolymer of propylene having an isotactic index greater than about 80%, preferably about 90% to about 99.5%; (b) a crystalline, random copolymer of propylene with an olefin selected from ethylene and C₄-Cιo -olefins wherein the polymerized olefin content is about 1-10%) by weight, preferably about 1% to about 4%, when ethylene is used, and about 1% to about 20%> by weight, preferably about 1%> to about 16%, when the C₄-Cιo α-olefin is used, the copolymer having an isotactic index greater than about 60%, preferably at least about 70%;

(c) a crystalline, random terpolymer of propylene and two olefins selected from ethylene and C₄-C α-olefins wherein the polymerized olefin content is about 1%) to about 5%) by weight, preferably about 1% to about 4%, when ethylene is used, and about 1% to about 20%) by weight, preferably about 1% to about 16%), when the C₄-Cιo α-olefins are used, the terpolymer having an isotactic index greater than about 85%;

(d) an olefin polymer composition comprising: (i) about 10%) to about 60%> by weight, preferably about 15%> to about 55%), of a crystalline propylene homopolymer having an isotactic index great than about 80%, preferably about 90 to about 99.5%>, or a crystalline copolymer of monomers selected from (a) propylene and ethylene, (b) propylene, ethylene and a C₄-C₈ α-olefin, and (c) propylene and a C₄-C₈ α-olefin, the copolymer having a polymerized propylene content of more than about 85% by weight, preferably about 90%) to about 99%», and an isotactic index greater than about 60%; (ii) about 3%> to about 25%> by weight, preferably about 5%> to about 20%o, of a copolymer of ethylene and propylene or a C₄-C₈ α-olefin that is insoluble in xylene at ambient temperature; and (iii) about 10%> to about 85%> by weight, preferably about 15% to about 65%>, of an elastomeric copolymer of monomers selected from (a) ethylene and propylene, (b) ethylene, propylene, and a C₄-C₈ α-olefin, and (c) ethylene and a C₄-C α-olefin, the copolymer optionally containing about 0.5% to about 10%> by weight of a polymerized diene and containing less than about 70%> by weight, preferably about 10%> to about 60%), most preferably about 12% to about 55%>, of polymerized ethylene, and being soluble in xylene at ambient temperature and having an intrinsic viscosity of about 1.5 to about 6.0 dl/g; wherein the total of (ii) and (iii), based on the total olefin polymer composition is about 50% to about 90%> by weight, and the weight ratio of (ii)/(iii) is less than about 0.4, preferably 0.1 to 0.3, and preferably the composition is prepared by polymerization in at least two stages; and (e) mixtures thereof. When an ethylene polymer material is used as the starting material for making the peroxide-containing olefin polymer material, the ethylene polymer material is preferably selected from: (a) homopolymers of ethylene; (b) random copolymers of ethylene and an α-olefin selected from C₃-C₁₀ α-olefins having a polymerized α-olefin content of about 1 to about 20% by weight, preferably about 1%> to about 16%; and (c) random terpolymers of ethylene and two C₃-C1₀ α-olefins having a polymerized α-olefin content of about 1%> to about 20%> by weight, preferably about 1% to about 16%>; and (d) mixtures thereof; wherein the C₃-Cκ) α-olefins include the linear and branched alpha-olefms such as, for example, propylene, 1-butene, isobutylene, 1-pentene, 3-methyl-l-butene, 1-hexene, 3,4-dimethyl-l-butene, 1-heptene, 3 -methyl- 1-hexene, and 1-octene. When the ethylene polymer is an ethylene homopolymer, it typically has a density of 0.89 g/cm³ or greater, and when the ethylene polymer is an ethylene copolymer with a C₃-C₁₀ oi-olefins, it typically has a density of 0.91 g/cm or greater but less than 0.94 g/cm . Suitable ethylene copolymers include ethylene/butene-1, ethylene/hexene-1, ethylene/octene-1 and ethyl ene/4-methyl- 1-pentene. The ethylene copolymer can be a high density ethylene copolymer or a short chain branched linear low density ethylene copolymer (LLDPE), and the ethylene homopolymer can be a high density polyethylene (HDPE) or a low density polyethylene (LDPE). Typically the LLDPE and LDPE have densities of 0.910 g/cm³ or greater to less than 0.94 g/cm , and the HDPE and high density ethylene copolymers have densities greater than 0.940 g/cm , usually 0.95 g/cm³ or greater. In general, ethylene polymer materials having a density from 0.89 to 0.97 g/cm³ are suitable for use in the practice of this invention. Preferably the ethylene polymers are LLDPE and HDPE. When a butene-1 polymer material is used as the starting material for making the peroxide-containing olefin polymer material, the butene-1 polymer material is preferably selected from: (a) homopolymers of butene- 1 ; (b) copolymers or terpolymers of butene-1 with ethylene, propylene or C₅-C₁₀ alpha-olefin, the comonomer content ranging from about 1 mole % to about 15 mole %; and (c) mixtures thereof. Suitable polybutene-1 homo or copolymers can be isotactic or syndiotactic and have a melt flow rate (MFR) from about 0.1 to 150 dg/min, preferably from about 0.3 to 100, and most preferably from about 0.5 to 75. These butene-1 polymer materials, their methods of preparation and their properties are known in the art. Suitable polybutene-1 polymers can be obtained, for example, by using Ziegler-Natta catalysts with butene-1, as described in WO 99/45043, or by metallocene polymerization of butene-1 as described in WO 02/102811, the disclosures of which are incoφorated herein by reference. Preferably, the butene-1 polymer materials contain up to about 15 mole % of copolymerized ethylene or propylene. More preferably, the butene-1 polymer material is a homopolymer having a crystallinity of at least about 30%> by weight measured with wide- angle X-ray diffraction after 7 days, more preferably about 45 %> to about 70%, most preferably about 55%> to about 60%. The process of the present invention may be carried out in continuous or batch mode. Either in continuous or batch mode, an olefin polymer material and an organic peroxide are fed into a two-zone reactor, preferably at a feed rate of the organic peroxide from about 0.1 to about 20 parts of the organic peroxide per one hundreds parts (pph) of the olefin polymer material per minute, most preferably from about 0.2 to about 2 pph/min, thereby forming an olefin polymer mixture. The total amount of the organic peroxide used in the reaction is about 0.1 to about 10 wt%>, wherein the sum of the polymer material and the organic peroxide is 100 wt%_>. The amount of oxygen in the two-zone reactor is maintained at a concentration greater than 0.004%) by volume, preferably less than 15%, more preferably less than 8%, and most preferably from about 1.0 to about 5% by volume of oxygen in gas phase, at a temperature higher than 25°C but below the softening point of the polymer, preferably about 80 °C to about 140 °C or the softening point, whatever is lower, thereby forming a peroxide-containing olefin polymer. The reaction temperature in the first and second reaction zone could be the same or different. According to the batch mode, the peroxide-containing olefin polymer is optionally further treated at a temperature of at least 80°C but below the softening point of the polymer in an inert atmosphere with an oxygen concentration of 0.004%> by volume or less by removing the oxygen from the reactor to quench any reactive free radicals and remove degradation by-products from the organic peroxide. Or the peroxide-containing olefin polymer is optionally contacted with at least one polymerizable vinyl monomer, at a temperature from at least about 50°C to below the softening point of the polymer, by feeding the monomer into the two-zone reactor. According to the continuous mode, the peroxide-containing olefin polymer is discharged from the two-zone reactor and is optionally treated at a temperature of at least 80°C but below the softening point of the polymer in an inert atmosphere with an oxygen concentration of 0.004% by volume or less to quench any reactive free radicals and remove degradation by-products from the organic peroxide in a second reactor. Or the peroxide- containing olefin polymer is optionally contacted with at least one polymerizable vinyl monomer at a temperature from at least about 50°C to below the softening point of the polymer in a second reactor. The second reactor can be a two-zone reactor, an autoclave, or other reactors known by a person skilled in the art. Preferably, the second reactor is a two-zone reactor. The two-zone reactor is a reactor with two interconnected reaction zone, which comprises: a first interconnected reaction zone through which the polymer mixture flows under fast fluidization conditions, leaves said first reaction zone and enters a second interconnected reaction zone through which the polymer mixture moves in a plug flow mode by gravity, leaves said second reaction zone and is reintroduced into said first reaction zone, thus establishing a circulation of the olefin polymer between the two reaction zones. More specifically, the polymer particles flow through the first of said reaction zones under fast fluidization conditions, leave said first reaction zone through a pipe connector into a gas/solid separation means, such as a cyclone, which separates the solid particles from the gaseous material and the particles leave the gas/solid separation means and enter the second of said reaction zones through which they move in a plug flow mode by gravity, leave said second reaction zone by another pipe connector and are reintroduced into said first reaction zone, thus establishing a circulation of polymer between the two reaction zones. The gas flow introduced into the reactor has the high enough flow rate to circulate the polymer particles at a rate of about 0.5 to 10 cycles per minute, preferably about 1 to 4 cycles per minute. The reactor design and its operating conditions were disclosed in U.S. Pat. No. 5,696,203, which is incorporated herein by reference. In order to keep a controlled amount of oxygen in the reactor system, a constant addition of oxygen into the reactor is required to compensate the oxygen consumed in the reaction and vented to outside of the reactor. Suitable organic peroxides include acyl peroxides, such as benzoyl and dibenzoyl peroxides; dialkyl and aralkyl peroxides, such as di-tert-butyl peroxide, dicumyl peroxide; cumyl butyl peroxide; l,l,-di-tert-butylperoxy-3,5,5-trimethylcyclohexane; 2,5-dimethyl- l,2,5-tri-tert-butylperoxyhexane,and bis(alpha-tert-butylperoxy isopropylbenzene), and peroxy esters such as bis(alpha-tert-butylperoxy pivalate; tert-butylperbenzoate; 2,5- dimethylhexyl-2,5-di(perbenzoate); tert-butyl-di(perphthalate); tert-butylperoxy-2- ethylhexanoate, and l,l-dimethyl-3-hydroxybutylperoxy-2-ethyl hexanoate, and peroxycarbonates such as di(2-ethylhexyl) peroxy dicarbonate, di(n-propyl)peroxy dicarbonate, and di(4-tert-butylcyclohexyl)peroxy dicarbonate. The peroxides can be used neat or in diluent medium, having an active concentration of from about 10% to about 100%o by weight, preferably from 40 to 80% by weight, wherein the sum of the peroxide and the diluent medium is 100%. Particularly preferred is tert-butyl peroctoate as a 50 wt% dispersion in odorless mineral oil, sold commercially under the brand name Lupersol PMS. The number average molecular weight (M_n) of the peroxide-containing olefin polymer materials is preferably greater than 10,000, although it may be lower in some cases. The peroxide concentration in the peroxide-containing olefin polymers preferably ranges from about 1 to about 200 mmole of peroxide in one kilogram of the peroxide- containing olefin polymer (mmol/kg), more preferably from about 5 to about 150 mmol/kg, and most preferably from about 10 to 100 mmol kg. The peroxide containing olefin polymer material can be used to prepare a grafted copolymer by treating the peroxide-containing olefin polymer material with a vinyl monomer compound at an elevated temperature. More specifically, the grafting process comprises treating 100 parts of the peroxide-containing olefin polymer with about from 5 to 240 parts (pph) of at least one polymerizable monomer under free radical polymerization conditions, preferably about 10 to 80 pph, most preferably 20 to 40 pph at a temperature from at least about 50°C to below the softening point of the polymer. The vinyl monomer has one or more unsaturated bonds with and the monomer can contain a C₂-C ₀, straight or branched aliphatic chain or a substituted or unsubstituted aromatic, heterocychc, or alicyclic ring in a mono- or polycyclic compound. Preferably, the vinyl monomer is a C₂-C₂₀ vinyl monomer. Examples of the vinyl monomers are: styrene, vinylnaphthalene, vinylpyridine, vinylpyrrolidone, vinylcarbazole, methylstyrenes, methylchlorostyrene, p-tert-bulylstyrene, methylvinylpyridine, ethylvinylpyridine, acrylonitrile, methacrylonitrile, acrylic acid esters, methacrylic acid esters, unsaturated acid anhydride, metal salts of unsaturated acids and mixtures thereof, particularly styrene, acrylonitrile, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, methyl acrylate, butyl methacrylate, and mixtures thereof. Unless otherwise specified, the properties of the olefin polymer materials, compositions and other characteristics that are set forth in the following examples have been determined according to the test methods reported below: Melt Flow Rate ("MFR"): ASTM D1238, units of dg/min; 230° C; 2.16 kg; Polymer material with a MFR below 100, using full die; Polymer material with a MFR equal or above 100, using Vi die; unless otherwise specified. Isotactic Index ("LI."): Defined as the percent of olefin polymer insoluble in xylene. The weight percent of olefin polymer soluble in xylene at room temperature is determined by dissolving 2.5 g of polymer in 250 ml of xylene at room temperature in a vessel equipped with a stirrer, and heating at 135°C with agitation for 20 minutes. The solution is cooled to 25°C while continuing the agitation, and then left to stand without agitation for 30 minutes so that the solids can settle. The solids are filtered with filter paper, the remaining solution is evaporated by treating it with a nitrogen stream, and the solid residue is vacuum dried at 80°C until a constant weight is reached. These values correspond substantially to the isotactic index determined by extracting with boiling n-heptane, which by definition constitutes the isotactic index of polypropylene.

Peroxide Concentration: Quantitative Organic Analysis via Functional Groups, by S. Siggia et al., 4th Ed., NY, Wiley 1979, pp. 334-42.

Molecular Weight and

Molecular Weight Distribution

(MWD) The samples are prepared at a concentration of 70 mg/50 ml of stabilized 1, 2, 4 trichlorobenzene (250μg/ml BHT). The samples are then heated to 170 degC for 2.5 hours to solubilize. The samples are then run on a Waters GPCV2000 at 145°C at a flow rate of 1.0 ml/min. using the same stabilized solvent. Three Polymer Lab columns were used in series (Plgel, 20 μm mixed ALS, 300 X 7.5 mm).

Gas Chromatography

Determination of Oligomer

Content: Weigh accurately 7-8 g polymer sample into a 50 ml serum vial. Add 25 ml methylene chloride by pipette and cap the vial tightly with a teflon-lined septum seal (crimp the cap tightly to ensure seal is secure). Place the vial in a ultrasonic bath at room temperature. Remove a portion of the extract and analyze by Gas Chromatograph (Agilent 5890 or equivalent). In this specification, all parts, percentages and ratios are by weight unless otherwise specified. The peroxide-containing olefin polymers are prepared according to the following procedures.

Example 1 Peroxide-containing olefin polymers were prepared from a crystalline homopolymer of propylene, having a melt flow rate (MFR) of 9.4 dg/min, and I.I. of 96.5%, commercially available from Basell USA Inc. The homopolymer of propylene (2000g) was added into a 7 liter two zone reactor as described in General Procedures in U.S. Patent No. 5,696,203. A total gas flow rate in the reactor was kept at 28.3 standard liter per hour (SLH). An organic peroxide (100g), Lupersol PMS, which is a 50 wt% solution of t-butyl peroxy-2- ethylhexanoate in odorless mineral spirit (OMS), obtained from Atofina North America, Inc. was pumped into the reactor at a feeding rate of 4 g/min. The reactor was then heated up to 100°C under a controlled amount of oxygen in nitrogen as reported in Table 1. The reactor was maintained at 100°C for 60 minutes and then at 140°C for another 60 minutes. The oxygen was then removed and the reactor was held at 140°C°C under a blanket of nitrogen for another 60 minutes. Finally, the resultant olefin polymer was cooled, discharged and collected. The MFR of the olefin polymer and their peroxide concentration are summarized in Table 1. The reaction condition is correlated with the characteristics of the resultant polymer materials as demonstrated by the melt flow rate changes before and after the reaction. The melt flow rate and the peroxide content of the polymers increase with the increase of the oxygen concentration. Comparative samples are summarized in Table 2. The comparative samples 1 and 2 show the characteristics of the polymer after oxygen treatment under the same temperature treatment profile as those of the samples but without adding an organic peroxide. Comparative samples 1-2 show no significant increase in their MFRs indicating that there was no significant oxidation reaction under these conditions. Comparative sample 3 was prepared by using an irradiation method. The polymer starting material was irradiated at 0.5 Mrad under a blanket of nitrogen. The irradiated polymer was then treated with 1.45% by volume of oxygen at 80°C for 60 minutes and then with 1.45% by volume of oxygen at 140°C for an additional 60 minutes. The oxygen was then removed. The polymer was then heated at 140°C under a blanket of nitrogen for 60 minutes, cooled and collected. The data reported in Tables 1 and 2 show that the process of this invention carried out in a two-zone reactor is able to produce peroxide-containing olefin polymers with a high amount of peroxide functionality with respect to other methods known in the art.

The activity of the peroxide-containing olefin polymers prepared in Example 1 can be determined by measuring the polymerization reactivity in the presence of a vinyl monomer. About 85 pph of styrene monomer, commercially available from Aldrich Chemical Company, Inc., was added to the peroxide-containing olefin polymers and the mixture was sealed in a high pressure stainless steel pan. The pan was then placed in a differential scanning - calorimeter (DSC), model DSC 7 made by Perkin-Elmer Corporation. The mixture was heated from 25°C to 70°C at a heating rate of 20°C/min and then heated from 70°C to 170°C at a heating rate of l°C/min. Table 3 summarizes the polymerization enthalpy and the reaction conversion of the sample 1-3 and comparative samples 1-2.

The activity of the peroxide-containing polyolefins prepared in Example 1 was also been analyzed by DSC under isothermal conditions. About 85 pph of styrene monomer, commercially available from Aldrich Chemical Company, Inc., was added to the peroxide- containing polyolefins and the mixture was sealed in a high pressure stainless steel pan. The pan was then placed in a differential scanning calorimeter (DSC), model DSC 7 made by Perkin-Elmer Corporation. The mixture was heated from 25 °C to 140°C at a heating rate of 40°C/min and then held at the temperature for 120 min. Table 4 summarizes the polymerization enthalpy and the reaction conversion of the sample 1-3 and comparative samples 1-2.

Example 2 Peroxide-containing olefin polymers were prepared from a crystalline homopolymer of propylene, having a melt flow rate (MFR) of 9.8 dg/min, and I.I. of 96.5%>, commercially available from Basell USA Inc. The homopolymer of propylene (2000g) was added into a 7 liter two-zone reactor, having the set-up described in Example 1, under various total gas flow rates as outlined in Table 5. A specified amount of Lupersol PMS was pumped into the reactor at a feeding rate of 4 g/min for making samples 1-4. The reactor was then heated up to 100°C under a gas mixture having the controlled amount of oxygen in nitrogen reported in Table 5. The reactor was maintained at 100°C for a specified period of time and it was then heated to 140°C and held for 60 minutes at the same temperature. The oxygen was then removed and the reactor was held at 140°C under a blanket of nitrogen for another 60 minutes. Finally, the olefin polymer was cooled, discharged and collected. The characteristics of the resultant polymer materials are summarized in Table 5. Comparative Sample 1 is the crystalline homopolymer of propylene used as polymer starting material in samples 1-4. The peroxide-containing polymers in Table 5 shows significant changes in their melt flow rate, molecular weight, molecular weight distribution (MWD) and the oligomer content as measured by Gas Chromatography method defined herein. Samples 1-4 have higher MFR, lower molecular weight, molecular weight distribution and lower oligomer content as compared with those of the starting material.

SLH: standard liter per hour. Example 3 Peroxide-containing olefin polymers were prepared from a crystalline homopolymer of propylene, having a melt flow rate (MFR) of 9.8 dg/min, and I.I. of 96.5%, commercially available from Basell USA Inc. The homopolymer of propylene (2000g) was added into a 7 liter two-zone reactor, having the set up described in Example 1, under a total gas flow rate of 113.2 standard liters per hour (SLH). Lupersol PMS (lOOg) was pumped into the reactor at a feeding rate of 4 g/min for making samples 1-3. The reactor was then heated up to 100°C under a gas mixture having the controlled amount of oxygen in nitrogen reported in Table 6. The reactor was maintained at 100°C for 60 minutes and then heated to 140°C and held for 60 minutes. The oxygen was then removed and the reactor was held at 140°C under a blanket of nitrogen for another 60 minutes. Finally the olefin polymer was cooled, discharged and collected. The characteristics of the peroxide-containing olefin polymer materials are summarized in Table 6. Comparative Sample 1 was prepared under the same conditions as outlined above except that there was no organic peroxide added. The characteristics of the resultant polymer materials in Table 6 showed the effect of oxygen concentration on the resultant polymers.

Example 4 Peroxide-containing olefin polymers were prepared from a crystalline homopolymer of propylene, having a melt flow rate (MFR) of 9.8 dg/min, and I.I. of 96.5%o, commercially available from Basell USA Inc. The homopolymer of propylene (2000g) was added into a 7 liter two-zone reactor, having the set up described in Example 1, under a total gas flow rate of 4.0 SCFH. Lupersol PMS (100g) was pumped into the reactor at a feeding rate of 4 g/min for making Samples 1-2 and Comparative Sample 1. The reactor was then heated up to 100°C under a gas mixture having the controlled amount of oxygen in nitrogen reported in Table 7. The reactor was maintained at 100°C for 60 minutes and it was then heated to 140°C and held for 60 minutes. The oxygen was then removed and the reactor was held at 140°C under a blanket of nitrogen for another 60 minutes. Finally, the olefin polymer was cooled, discharged and collected. The characteristics of the resultant polymer materials are summarized in Table 7. Comparative Sample 1 was prepared under the same conditions as outlined above except that there was no oxygen added to the reactor. The changes in melt flow rate and molecular weight of the peroxide-containing polymers corresponded to the oxygen concentration used in the reactions.

Other features, advantages and embodiments of the invention disclosed herein will be readily apparent to those exercising ordinary skill after reading the foregoing disclosure. In this regard, while specific embodiments of the invention have been described in considerable detail, variations and modification of these embodiments can be effected without departing from the spirit and scope of the invention as described and claimed.

Claims

CLAIMS A process for making a peroxide-containing olefin polymer in a two-zone reactor with a first and a second interconnected reaction zones, into which particles of an olefin polymer and an organic peroxide are fed and from which the peroxide-containing olefin polymer is discharged, comprising: feeding into a two-zone reactor an olefin polymer and an organic peroxide, thereby forming an olefin polymer mixture comprising: I. about 90.0 to about 99.9 wt% of an olefin polymer material; II. about 0.1 to about 10.0 wt%> of an organic peroxide; wherein the sum of components I + II is equal to 100 wt%>; wherein the olefin polymer mixture is exposed to a controlled amount of oxygen greater than 0.004%> by volume of oxygen in gas phase, at a temperature at least 25°C but below the softening point of the polymer, thereby producing a peroxide-containing olefin polymer; wherein the two-zone reactor comprises a first interconnected reaction zone through which the polymer mixture flows under fast fluidization conditions, leaves said first reaction zone and enters a second interconnected reaction zone through which the polymer mixture moves in a plug flow mode by gravity, leaves said second reaction zone and is reintroduced into said first reaction zone, thus establishing a circulation of the olefin polymer between the two reaction zones.

2. The process according to claim 1 further comprising: treating the peroxide-containing olefin polymer at a temperature of at least 80°C but below the softening point of the polymer, in an inert atmosphere, with an oxygen concentration of 0.004%> by volume or less by removing the oxygen from the reactor.

3. The process according to claim 1 further comprising: treating the peroxide-containing olefin polymer at a temperature of at least 80°C but below the softening point of the polymer, in an inert atmosphere, with an oxygen concentration of 0.004%) by volume or less, in a second reactor after discharging the olefin polymer from the two-zone reactor.

4. The process according to claim 1 further comprising: contacting the peroxide-containing olefin polymer with at least one polymerizable vinyl monomer, at a temperature from at least about 50°C to below the softening point of the polymer, by feeding the polymerizable vinyl monomer into the two-zone reactor.

5. The process according to claim 1 further comprising: contacting the peroxide-containing olefin polymer with at least one polymerizable vinyl monomer at a temperature from at least about 50°C to below the softening point of the polymer in a second reactor after discharging the olefin polymer from the two-zone reactor.

6. The process according to claims 4 or 5, wherein the vinyl monomer has one or more unsaturated bonds and the monomer can contain a straight or branched aliphatic chain or a substituted or unsubstituted aromatic, heterocychc, or alicyclic ring in a mono- or polycyclic compound.

7. The process according to of claim 6, wherein the vinyl monomer is selected from styrene, vinylnaphthalene, vinylpyridine, vinylpyrrolidone, vinylcarbazole, methylstyrenes, methylchlorostyrene, p-tert-bulylstyrene, methylvinylpyridine, ethylvinylpyridine, acrylonitrile, methacrylonitrile, acrylic acid esters, methacrylic acid esters, unsaturated acid anhydrides, salts of unsaturated acids and mixtures thereof.

8. The process according to claim 1 wherein the olefin polymer material is selected from a propylene polymer material, an ethylene polymer material and a butene-1 polymer material.

9. The process according to claim 8 wherein the propylene polymer material is selected from: (a) a crystalline homopolymer of propylene having an isotactic index greater than about 80%; (b) a crystalline, random copolymer of propylene with an olefin selected from ethylene and C₄-Cι₀ α-olefins wherein the polymerized olefin content is about l-10%o by weight when ethylene is used, and about 1%> to about 20%> by weight when the C₄-Cι₀ α-olefin is used, the copolymer having an isotactic index greater than about 60%; (c) a crystalline, random terpolymer of propylene and two olefins selected from ethylene and C₄-C₈ α-olefins wherein the polymerized olefin content is about 1%) to about 5%> by weight when ethylene is used, and about 1%> to about 20% by weight when the C₄-Cι₀ α-olefins are used, the terpolymer having an isotactic index greater than about 85%>; (d) an olefin polymer composition comprising: (i) about 10%) to about 60% by weight of a crystalline propylene homopolymer having an isotactic index greater than about 80% or a crystalline copolymer of monomers selected from (a) propylene and ethylene, (b) propylene, ethylene and a C₄-C₈ α-olefin, and (c) propylene and a C₄-C₈ α-olefm, the copolymer having a polymerized propylene content of more than about 85%> by weight, and an isotactic index greater than about 60%>; (ii) about 3%> to about 25%> by weight of a copolymer of ethylene and propylene or a C₄-C₈ α-olefin that is insoluble in xylene at ambient temperature; and (iii) about 10%> to about 85%> by weight of an elastomeric copolymer of monomers selected from (a) ethylene and propylene, (b) ethylene, propylene, and a C₄-C₈ α-olefin, and (c) ethylene and a C₄-C₈ α-olefin, the copolymer optionally containing about 0.5%> to about 10%) by weight of a polymerized diene and containing less than about 70%) by weight of polymerized ethylene, and being soluble in xylene at ambient temperature and having an intrinsic viscosity of about 1.5 to about 6.0 dl g; wherein the total of (ii) and (iii), based on the total olefin polymer composition is about 50%) to about 90%> by weight, and the weight ratio of (ii)/(iii) is less than about 0.4, and the composition is prepared by polymerization in at least two stages; (e) mixtures thereof.

10. The process according to claim 9 wherein the propylene polymer material is a crystalline homopolymer of propylene having an isotactic index greater than 80%.

11. The process according to claim 8 wherein the ethylene polymer material is selected from: (a) homopolymers of ethylene; (b) random copolymers of ethylene and an α-olefin selected from C₃-C₁₀ α-olefins having a polymerized α-olefin content of about 1%> to about 20%> by weight; (c) random terpolymers of ethylene and two C₃-C1₀ α-olefins having a polymerized α-olefin content of about 1%> to about 20%> by weight; and (d) mixtures thereof.

12. The process according to claim 8 wherein the butene-1 polymer material is selected from: (a) homopolymers of butene- 1 ; (b) copolymers or terpolymers of butene-1 with ethylene, propylene or C5-C10 alpha-olefin, the comonomer content from about 1 mole %> to about 15 mole %>; and (c) mixtures thereof.

13. The process according to claim 1 wherein the organic peroxide is a solution of t-butyl peroxy-2-ethylhexanoate and an inert diluent.

14. The process according to claim 13 wherein the solution is 50 wt%> t-butyl peroxy-2- ethylhexanoate in odorless mineral spirit.