MXPA00009934A - Propylene copolymers containing styrene units - Google Patents

Abstract

Isotactic-polypropylene-based copolymers having a homogeneous distribution of recurring units of formula (1) where R is a hydrogen, halide radical or hydrocarbyl radical optionally containing an atom selected from oxygen, nitrogen, sulphur, phosphorus and silicon and n is an integer ranging from 1 to 3;said copolymer having a 13C-NMR spectrum wherein the resonance signals attributable to the links between different monomeric units fall around 30, 34, 35, 45 and 47 ppm and present intensities at least two times higher than the resonance signals attributable to styrene-styrene sequences around 41 ppm and 44-46 ppm. A process for preparing said copolymers carried out in the presence of homogeneous catalytic systems comprising a metallocene compound and a cocatalyst. Functionalized copolymers obtainable from said isotactic-polypropylene-based copolymers. Graft copolymers comprising said isotactic-polypropylene-based copolymers as backbones.

Description

COPOLI ERQS DE PRQPILENQ CONTAINING UNITS OF ESTIRENQ DESCRIPTIVE MEMORY The present invention relates to random copolymers of propylene as main recurring units comprising recurring units that are derived from styrene. The present invention also relates to functionalized copolymers and graft copolymers. The invention, moreover, relates to processes for the production of said copolymers. The present invention lies in the technical field of the production of thermoplastic materials. As is well known, plastic materials based on isotactic polypropylene are among the most interesting from the point of view of technology. In fact, they are not only competitive from a cost perspective, but also suitable for various applications due to adequate chemical and physical modifications. The chemical modification used mainly in industry is the random copolymerization of propylene with small amounts of one or more comonomers, usually ethylene or butene-1. This modification allows obtaining materials that have a lower melting temperature (mostly used to produce films with thermowelded layers), lower stiffness, higher impact strength at low temperatures and higher transparency than isotactic propylene homopolymer The variations mentioned above in physical properties with respect to the homopolymer are due to lower cnsta nity and smaller size of cpstalites caused by the comonomer units It is worth noting that the recurring units of ethylene and butene-1 have a steric hindrance sufficiently similar to the recurrent units of propylene. Consequently, although they cause a decrease in packing energy, they are partially enclosed as defects in the crystalline phase As is well known, generally speaking, in semicpstalin polymephous materials a more efficient decrease in cpstallite size and size is obtained when comonomer units with higher impediment are used than the basic monomer units, ie they must be excluded in a manner inevitable of the crystalline phase In this connection, however, there is a problem that cheap and impeded comonomers, such as styrene, are not easily copolymerizable with propylene, because the generally catalytic sites suitable for the isotactic polymerization of propylene are not capable of polimeprating styrene and vice versa In fact, generally speaking, catalytic systems suitable for the polymerization of 1-alkenes to isotactic polymers, such as catalysts based on metallocenes and methylalumoxane, are not able to polymerize styrene. On the contrary, styrene tends to act as a poison in such procedures. It is worth noting that in the case of heterogeneous catalysts, which typically contain different types of catalytic sites, it is possible to polymerize mixtures of the two mentioned monomers but mainly mixtures of the two homopolymers are obtained. Another disadvantage of known random copolymers based on propylene produced by heterogeneous catalysts is that the macromolecules do not have a homogeneous content of the comonomer units, so that fractions with a higher comonomer content are more easily extractable with solvents. This obviously limits its use to prepare articles to be used in contact with food. European patent application EP-A-872 492 describes catalytic systems based on stereorigid metallocenes containing a metal atom belonging to group IV of the periodic table and whose substituted cyclopentadienyl groups are bridged through a single atom. Said metallocenes are capable of copolymerizing olefins with aromatic vinyl compounds. As described in the patent application, said catalyst systems, however, produce copolymers containing blocks of styrene units. This is, for example, demonstrated by the nuclear magnetic resonance spectrum of Figure 29, therein.

A random copolymer of propylene having a homogeneous distribution of recurring units deriving from styrene in the polymer chain has now been produced. Thanks to the homogeneous distribution of the recurring units of styrene in the polymer chain, the polymers of the invention of the at the moment they show essentially no change in glass transition temperature compared to isotactic polypropylene. For example, in the case of propylene copolymers of the present invention, no increase in the glass transition temperature higher than 10 ° C is observed in comparison with isotactic polypropylene, for example, if Tg is measured by differential scanning calorimetry, at a rate of 10 ° K per minute, its value does not exceed 0 ° C It is important to note that possible random copolymers of propylene with styrene or substituted styrenes would present a substantial increase in glass transition temperature (Tg) compared to the propylene homopolymer, roughly in accordance with the ratio Fox where W pr0p and W styr are respectively propylene and styrene by weight fractions and Tg prap and Tg styr are respectively the glass transition temperatures of propylene homopolymer homogenous and poitherirene.

Glass transition temperatures of styrene polymers are much higher than those of polypropylene and the molecular mass of the styrenic units is much higher than that of the propylene unit, a substantial increase in glass transition temperature should be observed also in cases of a low mole content of the styrenic units and this would render said materials unusable in applications that demand a low operating temperature. As another advantage, some copolymers of the present invention can be used to prepare functionalized polypropylene as well as copolymers The present invention therefore provides new copolymers based on isotactic polypropylene having a homogeneous distribution of recurring units of the formula (1) wherein R is a hydrogen, halogenide radical, or a hydrocarbyl radical optionally containing an atom selected from oxygen, nitrogen, sulfur, phosphorus and silicon and n is an integer in the scale from 1 to 3 The copolymers of the present invention contain the units of formula (1) preferably in amounts ranging from 0 1 to 30% by weight • "-" * '* - • *' Said copolymers have a 13 C-NMR spectrum in which the resonance signals attributable to the links between different monomepcas units fall around 30, 34, 35, 45 and 47 ppm and have intensities at least 2 times higher than the resonance signals atpbuibles to styrene-styrene sequences of about 41 ppm and 44-46 ppm (all chemical shifts are relative to tetramethylsilane) In particular, for the case R of formula (1) is hydrogen, which is for styrene-comonomer units ethene, the resonance signals atpbuble to the bonds between different monomenca units fall to 30 3, 33 9, 34 6, 44 8, 46 9 ppm The degree of polymerization of the copolymers of the present invention is normally at least 50 When R is a substituent containing carbon atoms, can be selected from linear or branched C1-C20 alkyl radicals, C3-C20 cycloalkyl radicals and C6-C20 anlo radicals. They may be saturated or unsaturated radicals. Preferred radicals are methyl, ethyl, isopropyl, vinyl and halo radical. Said substituent R may contain a functional group, such as -NR2, wherein R is an alkyl group as defined above. sequences of recurrent propylene units are mainly isotactic In general, the content of meso diadas (m) is higher than 80% The amount of the structural units of formula (1) in the copolymer can be determined based on the intensity of specific signals in the 13C nuclear magnetic resonance spectrum. For example, in the case of copolymers of propylene with styrene the presence of said structural units is evidenced by signals in the aliphatic region at 33 9 and 25 2 ppm (chemical shift of tetramethylsilane, TS) and the mole fraction of the styrene units ( Xs), equal to the molar fraction of the connected ethylenic units, can be obtained by the following relationship Xs = (0 5A 39 + A252) + (0 5A339 + A252 + A244) + (A448 + 0 5A3 6 + A454 + 0 5A369) where Ax is the intensity of the ax ppm signal Depending on the polymerization conditions, random copolymers with various compositions and degrees of polymerization are obtained. In general, the average molecular weight PP is between 3,000 and 1,000,000 As mentioned above , the copolymers of the invention have a homogenous distribution of the comonomers. Such homogeneity is also tested by the impossibility by extraction of solvent to obtain fractions of the copolymers with an Xs value that differs more than 50% from the Xs value of the unfractionated sample. The copolymers of the instant invention can be obtained according to the known polymerization methods. The copolymers can be produced by means of the homogeneous catalyst systems used for the propylene insertion polymerization which gives an isotactic homopolymer, for example, catalyst systems based on metallocene compounds. Suitable examples of said metallocene compounds are rac-ethylene-bis (1-indenyl) -ZrCl2, rac -sopropylidene-b1s (1-indenyl) -ZrCl2, rac-dimethylsilyl-bis (1-indenyl) -ZrCl2, rac-dimethylsilyl-bis (2-methyl-1-indenyl) -ZrCl2, rac-dimethylsilyl-bis (2-methyl-4-isopropyl-1-indenyl) -ZrCl2, rac-dlmethylsil bis (2-methyl-4-phenyl-1-indenyl) -ZrCl2, rac-dimethylsilyl-bis (2-methyl-benz [e] -1-indenl) -ZrCl2, rac-dimethylsilyl-bis (benz [ e] -1-indenyl) -ZrCl2.

Suitable co-catalysts according to the process of the invention are alumoxanes or compounds capable of forming an alkyl metallocene cation. The alumoxanes useful as co-catalysts can be linear alumoxanes of formula (2): wherein R1 is selected from the group consisting of halogen, C?-C20 alkyl, C3-C2o cycloalkyl, C6-C2o aryl, C7-C20 alkylaryl, and C7-C20 arylalkyl, straight or branched, saturated or unsaturated, and is on a scale of 0 to 40; or cyclic alumoxanes of formula (3): wherein R1 has the meaning described herein and is an integer on the scale from 2 to 40. The above alumoxanes can be obtained according to procedures known in the art, by reacting water with an organoaluminum compound of formula AIR13 or AI2R16, with the proviso that at least one R1 is not halogen. In this case, the molar ratios of Al / water in the reaction are between 1: 1 and 100: 1. Particularly suitable are organometallic aluminum compounds of formula (II) described in EP 0 575 875 and those of formula (II) described in WO 96/02580. Moreover, suitable co-catalysts are those described in WO 99/21899 and in European patent application No. 99203110.4. The molar ratio between aluminum and the metal of the metallocene is between 10: 1 and 5000: 1, and preferably between 100: 1 and 4000: 1.

Examples of suitable alumoxanes as co-catalysts for activation in the process of the invention are methylalumoxane (MAO), tetra-isobutyl-alumoxane (TIBAO), tetra-2,4,4-tr? Met? Lpent? Lamoxane (TIOAO) and tetra-2-met? l-pent? lamoxane Mixes of different alumoxanes can also be used Non-limiting examples of aluminum compounds of formula AIR83 or AI2R86 are Tr? s (met? l) alum? n? o, tps (? sobut ? l) alum? n? o, tr? s (? sooct? l) alum? n? o, b? s (? sobut? l) alum? n? o hydruro, met? lb? s (? sobut? l) ) alum? n? o, d? met? l (? sobut? l) alum? n? o, tps (? sohex? l) alum? n? o, ps (benc? l) alum? n? o, tps (tol? l) alum? n? o, tr? s (2,4,4-tpmet? lpent? l) alum? n?, b? s hydride (2,4,4-tr? met? lpent ? l) alum? n? o,? sobut? lb? s (2-fen? l-prop? l) alum? n? o, d? sobut? l- (2-phen? l-prop? l) alum? n? o,? sobut? lb? s (2,4,4-tnmet? l-pent? l) alum? n? o, d? sobut? l- (2,4,4-tr? met ? l-pent? l) alum? n? o, tr? s (2,3-d? met? l-hex? l) alum? n? o, tr? s (2,3,3-tpmet? l -but? l) alum? n? o, tps (2,3-d? met? l-but? l) alum? n? o, tr? s (2,3-d? met? l-pent? l) ) alum? n? o, tr? s (2-met? l-3- et? l-pent? l) alum? n? o, tr? s (2-et? l-3-met? l-but? l) alum? n? o, tps (2-et? l-3- met? l-pent? l) alum? n? o, tr? s (2-? soprop? l-3-met? l-but? l) alum? n? oy tr? s (2,4-d? metil-hept? l) alum? n? Particularly preferred aluminum compounds are tmethylamumium (TA), tr? s (2,4,4-tr? met? lpent? l) alum? n? o (TIOA ), triisobutylaluminum (TIBA), tps (2,3,3-t-methyl-l-butyl) alum? n? oy tr? s (2,3-d? met? l-but? l) alum? n? or Mixtures of organometallic aluminum compounds and / or alumoxanes can also be used. In the catalyst system used in the process of the invention, the metallocene and alumoxane can be pre-reacted with an organometallic aluminum compound of formula AIR13 or Al2R1ß, in which R has the meaning reported above. The additional suitable co-catalysts in the catalysts of the invention are those compounds capable of forming an alkylmetallocene cation. Examples are compounds of boron and tetrakis-pentafluorophenyl-borate is particularly preferred. Moreover, they can be used conveniently compounds of formula BAr3 The catalysts of the present invention can also be used on an inert support, depositing the metallocene, or the reaction product of the metallocene with the co-catalyst, or the co-catalyst and successively the metallocene , on the inert support, such as silica, to lumina, magnesium halides, polymers or olefin prepolymers (ie polyethylenes, polypropylenes or styrene-divmylbenzene copolymers) The supported catalyst system obtained in this manner, optionally in the presence of alkylaluminum compounds, either untreated or pre-reacted with water, can be used in a useful manner in gas phase polymerization processes. The solid compound obtained in this way, in combination with additional addition of the compound of alkylaluminum as such or pre-reacted with water, is used in a useful manner in gas phase polymerization. The molecular weight of the polymers can be varied by changing the polymerization temperature or the type or concentration of the catalyst components, or by using regulators of molecular weight, such as hydrogen, as is well known in the art The polymerization process according to the present invention can be carried out in gas phase or in liquid phase, optionally in the presence of an inert hydrocarbon solvent either aromatic (such as toluene), or aliphatic (such as propane, hexane, heptane, isobutane and cyclohexane) The polymerization temperature is in the range of 0 ° C to 250 ° C, preferably 20 ° C to 150 ° C, and more preferably from 40 ° C to 90 ° C The molecular weight distribution can be varied by using different metallocene mixtures or by carrying out the polymerization in various steps which differ in the polymerization temperature and / or in the concentration of the polymerization monomers The polymerization yield depends on the purity of metallocenes in the catalysts, the metallocenes according to the present invention can be used as such or can be subjected to prior treatments purification The metallocenes and co-catalysts can be contacted in a suitable manner between them before polymerization. The contact time can be between 1 and 60 minutes, preferably between 5 and 20 minutes. The pre-contact concentrations for the metallocenes are between 10"2 and 10" 8 mol / l, while for the co-catalysts they are between 10 and 10"3 mol / I. The pre-contact is carried out generally in the presence of a hydrocarbon solvent and, optionally, small amounts of monomer The copolymerization of propylene and styrene is carried out in the presence of small amounts of ethylene, in particular, the concentration of propylene may be between 0.1 M and 13 M, the styrene concentration between 10"3 M and 9 M, the ethylene concentration of less than one tenth of the propylene concentration, the catalyst concentration between 10" 8 M and 10"2 M. The temperature of polymerization is between -30 ° C and + 150 ° C, preferably between 0 ° C and 100 ° C. The copolymers of the present invention can be mixed with other polymers, preferably with isotactic propylene polymers.

Said mixtures of polymers can be prepared by mechanical mixing of the polymers, at least at the mild temperature, preferably at the melting temperature, of the polymers. Alternatively, the mixture can be carried out in the manner of a polymerization which can be carried out in at least two sequential steps, in which the polymers are prepared in steps Subsequent separated, operating in each step, except in the first step, in the presence of the polymer formed in the previous step The catalysts can be the same in all steps or different For example, a Ziegler-Natta catalyst can be used in the first step , while said homogeneous catalyst systems can be used in the subsequent steps. The present invention also provides functionalized copolymers. As mentioned above, the copolymers of the present invention are particularly useful for producing functionalized copolymers, which are technologically important to improve their adhesion In fact, the comonomopro units of formula (1) can be functionalized under various ammonium and cationic processes, free radicals, as described in the open and patent literature for random copolymers between ethene and styrene or styrenes substitute For example, benzylic protons can be oxidized, halogenated or metalated, to form desirable functional groups (COOH, CH2X, and CH2Mt, respectively), attached to the femlo rings. Moreover, benzylic protons can be interconverted to stable ammonia initiators for Graft polymerizations In particular, the metallated polymer (mainly lithiated) can be suspended in an inert organic diluent before the addition of monomers, such as styrene, substituted styrenes, vimlo acetate, methyl acrylate, meta-plaque of methyl, acrylonitrile. This process can be particularly relevant for the preparation of graft copolymers having polystyrene branches in isotactic polypropylene base structures. Another object of the present invention are graft copolymers comprising isotactic polypropylene base copolymers as base structures. Examples of graft copolymers of the present invention are polystyrene or polyvinylacetate or polymethacrylate or polymethylmethacrylate or polyacrylonitrile grafted to isotactic polypropylene. Said graft copolymers can be obtained by the aforementioned method. These graft copolymers are mainly useful as compatibilizers in the preparation of mixtures or alloys of normally incompatible polymers. Examples of polymers to be mixed with the propylene polymers in the presence of the graft copolymers are polystyrene, polyether, polyacrylate, such as polymethylacrylate. The following examples are given only to illustrate the invention of the moment and not to limit its scope.

EXAMPLE 1 In a pyrex glass flask, of 100 mL, of three necks, kept at -25 ° C, they are introduced, under a nitrogen atmosphere, in order: styrene (30 mL) and methylalumoxane (MAO) (300 mg); after removing the nitrogen, the liquid phase becomes saturated by bubbling a mixture of propylene / ethylene (20/1 mole / mole) at atmospheric pressure, establishing the flow at 0.3 L per minute. The reaction is initiated by injecting into the flask 3 mg of rac-ethylene-bis (l-indenyl) ZrC catalyst dissolved in 2 mL of anhydrous toluene. After a reaction time of 4 hours, the polymer produced is coagulated in 200 mL of ethanol acidified with HCl, filtered and dried in a vacuum or in vacuo. The yield is approximately 120 mg. From the analysis of 13 C-NMR (Figures 1 and 1 B) the product turns out to be composed of 76% by moles of propylene units and 12% by mole of styrene units and 12% by mole of associated ethylene units (Xs = 0.12), while no significant amounts of blocks of styrene units are observed. Figure 1B shows that the resonance signal at approximately 41 ppm, which is attributable to the styrene-styrene sequences, is almost 6 times less intense than the resonance signal at 0.3 ppm and almost 3 times less intense than the resonance signals to 33.9, 34.6, 44.8, 46.9 ppm, all attributable to the links between different monomer units. This fact confirms the statistical nature of the product obtained. From the differential scanning calorimetric analysis, carried out with a scanning speed of 10 K / min, the polymer it turns out that it is characterized by a melting temperature of 79 ° C (? Hf = 10 J / g) and a Tg * -9 ° C. The average weight of the molecular mass measured by gel permeation chromatography is 3 x 103 u.m.a.

COMPARATIVE EXAMPLE 1 A polymerization of propylene-styrene is carried out with a catalyst system of the same type as that described in the Arai et al. Patent, cited above. In a pyrex glass flask with three necks, of 100 mL, maintained at 50 ° C, they are introduced, under a nitrogen atmosphere, in the following order: toluene (30 mL), styrene (5 mL), methylalumoxane (MAO) (600 mg), and t-isobutylaluminum (0.4 mL); After removing the nitrogen, the liquid phase becomes saturated causing the propylene to form bubbles at atmospheric pressure, establishing the flow at 0.3 L per minute. The reaction is initiated by injecting into the flask 5 mg of rac-isoprop? Lidena-bis (l-indenyl) ZrCl2 catalyst dissolved in 2 mL of anhydrous toluene. After a reaction time of 4 hours, the polymer produced is coagulated in 200 mL of ethanol acidified with HCl, filtered and dried in a vacuum oven. The yield is approximately 320 mg.

From the analysis of 13 C-NMR (Figures 2 and 2B) the product turns out that it is composed of 13 mol% styrene units Figure 2B shows that the resonance signals at approximately 41 and 43 ppm, which are atpbuible to the sequences of styrene-styrene, have intensities comparable to those of the resonance signals attributable to the links between different monomentric units, falling in the region of 30 to 38 ppm, regardless of the fact that the content of styrene units is lower than in the product of example 1 (8% vs 12%) This fact indicates the presence of blocks in the polymer EXAMPLE 2 The catalyst system used, the operating method and the reaction conditions are identical to those of Example 1, except for the amounts used of styrene (10 mL) and toluene (20 mL). The yield is approximately 200 mg. 13C-NMR the product results to be composed of 88% by mole of propylene units and 6% by mole of styrene units and 6% by mole of associated ethylene units (Xs = 0 06) From the differential scanning calorimetric analysis (DSC) ) the polymer is characterized by a melting temperature of 103 ° C (? Hf = 24 J / g) and a Tg »-13 ° C EXAMPLE 3 The reaction is carried out at 0 ° C in a 250 L autoclave containing 50 mL of toluene, 3.2 mL of styrene, 0.9 g of MAO and 9 mg of the same catalyst used in Examples 1 and 2, feeding a gaseous mixture ethylene / propylene (1/4 mole / mole) at 2 atmospheres. The reaction is stopped after 1 hour and approximately 600 mg of product are obtained (conversion < 5%). From the analysis of 13 C-NMR the sample results that it is characterized by a content of styrene units of 3% in moles (Xs = 0. 03), while the content of ethylene units is 7% and is distributed between sequences of ethylene units contiguous to styrene units < 3%) and sequences of ethylene units comprised between propylene units (4%).

The melting temperature of the polymer is 124 ° C (? Hf = 53 J / g) and The homogeneous distribution of the comonomers is confirmed by hydrocarbon solvent extraction tests: the polymer is completely soluble in boiling hexane and completely insoluble in boiling ethyl ether.

EXAMPLE 4 In a pyrex glass flask of 100 mL, with three necks, kept at -25 ° C, in the atmosphere of nitrogen, in the following order are introduced toluene (28 mL), p-methyl-styrene (2 mL) and methylalumoxane ( MAO) (460 mg), after removing the nitrogen, the liquid phase is saturated causing a mixture of propylene / ethylene (124/1 mole / mole) to form at atmospheric pressure, establishing the flow at 0 3 L per minute. reaction is initiated by injecting into the flask 6 mg of catalyst rac-et? len-b? s (1-? nden? l) ZrCl2 dissolved in 2 mL of anhydrous toluene After a reaction time of 3 hours, the polymer produced is coagulated in 200 mL of ethanol acidified with HCl, filtered and dried in a vacuum oven. The yield is approximately 500 mg. From the analysis of 13 C-NMR the polymer results to consist essentially of isotactic polypropylene and contains 0 7% by moles of p-methyl-styrene units and 0 9% by moles of ethylene units (of which 0 7% are associated with the p-methyl-styrene units, Xs = 0 07) From the calorimetric analysis of Differential scrutiny, carried out with a scanning speed of 10 K / mm, the polymer is characterized by a melting temperature of 134 ° C (? H, = 85 J / g) It is interesting to note that the isotactic polypropylene, obtained under the same conditions with this catalyst system, shows a melting temperature of 151 ° C (? Hf = 95 J / g).

EXAMPLE 5 The catalyst system used, the operating method and the reaction conditions are identical to those of Example 4, except for the fact that divinyl benzene is used in place of p-methyl-styrene and the composition of the propylene / ethylene mixture is of 75/1 mole / mole. The yield is approximately 500 mg. From the 13 C-NMR analysis the polymer results to consist essentially of isotactic polypropylene and contains 0.7 mol% of divinylbenzene units and 0.7 mol% of ethylene-associated units (X s = 0.007). From the differential scanning calorimetric analysis, carried out with a scanning speed of 10 K / min, the polymer is characterized by a melting temperature of 131 ° C (? Hf = 90 J / g).

Claims (2)

1. NOVELTY OF THE INVENTION CLAIMS 1 - . 1 - Copolymers based on isotactic polypropylene having a homogeneous distribution of recurring units of the formula (I): wherein R is a hydrogen, halide radical or a hydrocarbyl radical optionally containing an atom selected from oxygen, nitrogen, sulfur, phosphorus and silica and n is an integer in the scale from 1 to 3; said copolymer has a 13 C-NMR spectrum in which the resonance signals attributable to the links between different monomer units fall around 30, 34, 35, 45, and 47 ppm and have intensities at least twice as high as the signals of resonance attributable to styrene-styrene sequences around 41 ppm and 44-46 ppm.
2. 2. The copolymers according to claim 1, further characterized in that the content of recurring units of formula (1) is in the range of 0.1 to 30% by weight. 3 - . 3 - The copolymers according to claim 1, further characterized in that they have the degree of polymerization of at least 50 - The copolymers according to claim 1, further characterized in that R is selected from linear or branched C 2 C alkyl radicals , C3-C20 cycloalkyl radicals and C6-C2 alkyl The alkyl radicals can be saturated or unsaturated radicals. 5 - The copolymers according to claim 4, further characterized in that R is selected from methyl, ethyl, isopropyl, vinyl and amyl radicals 6 - The copolymers according to claim 1 and 4, further characterized in that the substituent R contains a group functional 7 -. 7 - The copolymers according to claim 1, further characterized in that the content of meso diadas (m) is higher than 80% 8 - A process for preparing the copolymer according to claim 1 carried out in the presence of catalyst systems homogeneous compounds comprising a metallocene compound and a cocatalyst 9 - The copolymers function which are obtained from the copolymers based on isotactic polypropylene according to claim 1 10. - Graft copolymers comprising copolymers based on isotactic polypropylene according to claim 1 as base structures. 11. Graft copolymers according to claim 10 selected from polystyrene or polyvinylacetate or polymethacrylate or polymethylmethacrylate or polyacrylonitrile grafted to isotactic polypropylene.