JP2002536514A - Propylene copolymer containing styrene units - Google Patents

Abstract

(57) [Summary] Formula (1): Wherein R is hydrogen, a halide group or a hydrocarbon group optionally containing an atom selected from oxygen, nitrogen, sulfur, phosphorus and silicon, and n is an integer of 1 to 3. The resonance signal attributable to the bond between the different monomer units having a homogeneous distribution is at around 30, 34, 35, 45 and 47 ppm, at least 41 ppm and at least more than the resonance signal attributable to the styrene-styrene sequence around 44-46 ppm. Isotactic-polypropylene-based copolymer with a ¹³ C-NMR spectrum showing twice the intensity. A method for producing the polymer in the presence of a homogeneous catalyst system comprising a metallocene compound and a cocatalyst. Functionalized copolymers obtained from said isotactic-polypropylene-based copolymer. A graft copolymer comprising the isotactic-polypropylene-based copolymer as a skeleton.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to random copolymers of propylene as the main repeating unit consisting of repeating units derived from styrene. The invention also relates to the functionalized and graft copolymers. The invention further relates to a method for preparing the copolymer. The present invention is in the technical field of the production of thermoplastics.

As is well known, plastic materials based on isotactic polypropylene are of most interest from a technology point of view. In fact, they are not only competitive from a cost perspective, but are also suitable for various applications due to appropriate chemical and physical modifications. The chemical modification most used in the industry is the random copolymerization of propylene with small amounts of one or more comonomers, usually ethylene or butene-1. The modification results in a lower melting point (particularly used to produce films with heat-weldable layers), lower stiffness, higher impact resistance at low temperatures and higher transparency than isotactic polypropylene homopolymers A substance having properties is obtained.

[0003] The above changes in physical properties for homopolymers are due to the lower crystallinity caused by the comonomer units and smaller size crystallites. It is worth noting that ethylene and butene-1 repeat units have steric hindrance sufficiently similar to propylene repeat units. Thus, although they reduce the filling energy, they are partly encapsulated as defects in the crystalline layer. As is well known, in general, in semi-crystalline polymeric materials, when using comonomer units having a higher degree of hindrance than the basic monomer units, i.e., they must necessarily be excluded from the crystalline layer. A more effective reduction in crystallinity and crystal size.

[0004] However, in connection with this, there is a problem that hindered and inexpensive comonomers such as styrene are not easily copolymerizable with propylene. This is because the catalytic sites suitable for isotactic polymerization of propylene are usually not capable of polymerizing styrene. In fact, generally metallocene- and methylalumoxane-
Suitable catalyst systems for the polymerization of 1-alkenes into isotactic polymers, such as base catalysts, are not capable of polymerizing styrene. Conversely, styrene tends to act toxic in such processes. It is worth noting that in the case of heterogeneous catalysts, which typically contain different types of catalytic sites, the mixture of the two monomers can be polymerized, but a mixture of the two homopolymers is largely obtained. .

Another disadvantage of the known random copolymers based on propylene prepared with heterogeneous catalysts is that the macromolecules do not have a homogeneous content of comonomer units, so that fractions having a higher comonomer content Can be more easily extracted with a solvent. This clearly limits its use for producing articles used in contact with food.

[0006] European patent application EP-A-87 492 describes a stereorigid composition comprising a metal atom belonging to group IV of the periodic table, wherein the substituted cyclopentadienyl group is bridged by a single atom. A catalyst system based on a stereorigid metallocene is disclosed. The metallocene is capable of copolymerizing a vinyl aromatic compound and an olefin. As described in the above-mentioned patent application, such catalyst systems, however, produce copolymers containing blocks of styrene units. This is illustrated, for example, by the nuclear magnetic resonance of FIG. 29 therein.

[0007] Random copolymers of propylene have now been produced having a homogeneous distribution of repeating units derived from styrene in the polymer chain.

[0008] Due to the homogenous distribution of the styrene repeat units in the polymer chain, the copolymers of the invention show essentially no change in the glass transition temperature compared to isotactic polypropylene. For example, it has been observed that the propylene copolymers of the present invention do not show an increase in glass transition temperature greater than 10 ° C. as compared to isotactic polypropylene. For example, when T _g is measured by differential calorimetry at a rate of 10 ° K / min, the value does not exceed 0 ° C.

[0009] Possible random copolymers of propylene and styrene or substituted styrene have an approximate Fox relationship compared to propylene homopolymer:

(Equation 1) _Where W _prop and W _styr are the weight fractions of propylene and styrene, respectively, and T _{g prop} and T _{g styr} are the glass transition temperatures of the polypropylene and polystyrene homopolymers, respectively. It is important to note that it shows a substantial increase in (T _g ). Because the glass transition temperature of styrene polymers is much higher than that of polypropylene, and the molecular mass of styrene units is much higher than that of propylene units, a substantial increase in glass transition temperature is due to the lower molar content of styrene units. It is also found in quantities, which renders the material unusable in applications requiring low continuous temperatures.

[0010] As another advantage, some copolymers of the present invention, as well as graft copolymers, can be used to make functionalized polypropylene.

The present invention therefore provides a method of formula (1):

Embedded image Wherein R is hydrogen, a halide group or a hydrocarbon group optionally containing an atom selected from oxygen, nitrogen, sulfur, phosphorus and silicon, and n is an integer in the range of 1-3. Novel isotactic-polypropylene-based copolymers having a homogeneous distribution of

The copolymers of the present invention contain recurring units of formula (1), preferably in amounts ranging from 0.1 to 30% by weight.

The copolymer has resonance signals attributable to bonds between different monomer units of 30,34.
, Located near 35, 45 and 47 ppm, styrene near 41ppm and 44～46Ppm - shows a higher strength than at least 2 times greater than attributed resonance signal styrene sequence ¹³ C-
It has an NMR spectrum (all chemical shifts relate to tetramethylsilane). In particular, when R in formula (1) is hydrogen, ie, a styrene-ethene comonomer unit, the resonance signals attributable to the bond between the different monomer units are 30.3, 33.9, 34.6.
, 44.8, and 46.9 ppm.

The degree of polymerization of the copolymer of the present invention is usually at least 50. When R is a substituent containing a carbon atom, it can be selected from linear or branched C ₁ -C ₂₀ alkyl groups, C ₃ -C ₂₀ cycloalkyl groups and C ₆ -C ₂₀ aryl groups. The alkyl group may be a saturated or unsaturated group. Preferred groups are methyl, ethyl, isopropyl, vinyl and aryl groups.

The substituent R may include a functional group such as —NR _2, wherein R is an alkyl group as defined above.

The sequence of the propylene repeating units is preferably predominantly isotactic. In general, the content of meso dyads (m) is higher than 80%.

The amount of structural units of formula (1) in the copolymer is determined on the basis of the intensity of a particular signal in the ¹³ C nuclear magnetic resonance spectrum. For example, in the case of a propylene copolymer with styrene, the presence of the structural unit is evidenced by a signal in the fatty region at 33.9 and 25.2 ppm (tetramethylsilane, chemical shift from TMS), and the styrene unit (X _S ) Is equal to the molar fraction of bound ethylene units, with the following relationship:

(Equation 2) Wherein A _x is the intensity of the signal at _x ppm.

[0018] Depending on the polymerization conditions, random copolymers having various compositions and degrees of polymerization can be obtained. Usually average molecular weight

(Equation 3) Is 3,000 to 1,000,000.

As mentioned above, the copolymers of the present invention have a homogeneous distribution of comonomer.
Such homogeneity is also evidenced by solvent extraction to obtain fractions of the copolymers with different X _S value of 50% or more from the X _S value of unfractionated samples is not possible.

The copolymer of the present invention can be obtained by a known polymerization method.

[0021] The copolymer can be prepared using a homogeneous catalyst system that is used for the insertion polymerization of propylene and provides an isotactic homopolymer, for example, a catalyst system based on a metallocene compound. Suitable examples of the metallocene compound include rac-ethylene-bis (1-indenyl) -ZrCl ₂ , rac-isopropylidene-bis (1-indenyl) -ZrCl ₂ , rac-dimethylsilyl-bis (1-indenyl) -ZrCl _2, rac- dimethylsilyl - bis (2-methyl-1-indenyl) -ZrCl _2, rac- dimethylsilyl - bis (2-methyl-4-isopropyl-1-indenyl) -ZrCl _2, rac- dimethylsilyl -Bis (2-methyl-4-phenyl-1-indenyl) -ZrCl ₂ , rac-dimethylsilyl-bis (2-methyl-
Benz [e] -1-indenyl) -ZrCl ₂ and rac-dimethylsilyl-bis (benz [e] -1-indenyl) -ZrCl ₂ .

Suitable active cocatalysts according to the process of the invention are compounds capable of forming an alumoxane or alkyl metallocene cation.

Alumoxanes useful as cocatalysts have the formula (2):

Embedded image Wherein R ¹ is halogen, linear or branched, saturated or unsaturated C ₁ -C ₂₀ alkyl, C ₃ -C ₂₀ cycloalkyl, C ₆ -C ₂₀ aryl, C ₇ -C ₂₀ alkylaryl and is selected from the group consisting of C ₇ -C ₂₀ arylalkyl group, y is 0 to 4
0] or a linear alumoxane of the formula (3):

Embedded image Wherein R ¹ has the meaning described herein and y is an integer in the range of 2 to 40.

The alumoxane has the formula A under the condition that at least one R ¹ is not halogen.
lR by reacting water ¹ ₃ or an organic aluminum compound of Al ₂ R ¹ _6, can be obtained according to methods known in the art. In this case, the Al
The / water molar ratio is between 1: 1 and 100: 1. The formula (EP0575875)
Organoaluminum compounds of the formula (II) and the formulas (II) described in WO 96/02580
) Are particularly suitable. Further, suitable cocatalysts are described in WO 99/21899.
And European Patent Application No. 99203110.4.

The molar ratio of metal to aluminum and metallocene is from about 10: 1 to about 5000: 1, preferably from about 100: 1 to about 4000: 1.

Examples of alumoxanes suitable as activity cocatalysts in the process of the present invention are methylalumoxane (MAO), tetra-isobutyl-alumoxane (TIBAO), tetra-2,4,4-trimethylpentylalumoxane (TIOAO) and Tetra-2-methyl-pentylalumoxane. Mixtures of different alumoxanes can also be used.

[0027] Non-limiting examples of formula AlR ⁸ ₃ or aluminum compounds Al ₂ R ⁸ ₆ are: tris (methyl) aluminum, tris (isobutyl) aluminum, tris (isooctyl) aluminum, bis (isobutyl) aluminum hydride, methyl -Bis (isobutyl) aluminum, dimethyl (isobutyl) aluminum, tris (isohexyl) aluminum, tris (benzyl) aluminum, tris (tolyl) aluminum, tris (2,4,4-trimethylpentyl) aluminum, bis (2,4, 4-trimethylpentyl) aluminum hydride, isobutyl-bis (2-phenyl-propyl) aluminum, diisobutyl- (2-phenyl-propyl) aluminum, isobutyl-bis (2,4,4-trimethyl-pentyl) aluminum, diisobutyl- ( 2,4,4-trime Le - pentyl) aluminum, tris (2,3-dimethyl -
Hexyl) aluminum, tris (2,3,3-trimethyl-butyl) aluminum, tris (2,3-dimethyl-butyl) aluminum, tris (2,3-dimethyl-pentyl)
Aluminum, tris (2-methyl-3-ethyl-pentyl) aluminum, tris (
2-ethyl-3-methyl-butyl) aluminum, tris (2-ethyl-3-methyl-pentyl) aluminum, tris (2-isopropyl-3-methyl-butyl) aluminum and tris (2,4-dimethyl-heptyl) Aluminum.

Particularly preferred aluminum compounds are trimethylaluminum (TMA), tris (2,4,4-trimethylpentyl) aluminum (TIOA), triisobutylaluminum (TIBA), tris (2,3,3-trimethyl-butyl) Aluminum and tris (2,3-dimethyl-butyl) aluminum.

Mixtures of different organometallic aluminum compounds and / or alumoxanes are also
Can be used.

[0030] In the catalyst system used in the method of the present invention, both the metallocene and the alumoxane, ¹ ₃ or Al ₂ R ¹ ₆ [In the formula, R ¹ has the meaning given above formula AlR organometallic aluminum compounds May be preliminarily reacted.

Further active cocatalysts suitable in the catalyst according to the invention are compounds which can form alkyl metallocene cations. Examples are boron compounds, with tetrakis-pentafluorophenyl-borate being particularly preferred. In addition, compounds of the formula BAr ₃ can usually be used.

The catalysts of the present invention can be prepared by reacting a metallocene, the reaction product of a metallocene and a cocatalyst, or a cocatalyst followed by a metallocene on an inert support with silica, alumina, magnesium halide, olefin polymer or prepolymer (ie, polyethylene,
It can also be used by deposition on an inert support such as polypropylene or styrene-divinylbenzene copolymer). The supported catalyst system thus obtained can be usefully used in a gas phase polymerization process, without treatment with water or pre-reaction with water, optionally in the presence of an alkyl aluminum compound. Further, the solid compound thus obtained, which has been combined with the addition of the alkylaluminum compound itself or preliminarily reacted with water, can be usefully used in a gas phase polymerization method.

The molecular weight of the polymer can be varied by changing the polymerization temperature or the type or concentration of the catalyst component, or by using a molecular weight regulator known in the art, such as hydrogen.

The polymerization process according to the invention is characterized in that, in the gas or liquid phase, an inert carbon, optionally aromatic (such as toluene) or aliphatic (such as propane, hexane, heptane, isobutane and cyclohexane) It can be carried out in the presence of a hydride solvent.

[0035] The polymerization temperature ranges from about 0 ° C to about 250 ° C, preferably 20 ° C to 150 ° C, more preferably 40 ° C to 90 ° C.

[0036] The molecular weight distribution can be varied by using a mixture of different metallocenes or by performing the polymerization in various steps with different polymerization temperatures and / or concentrations of polymerized monomers.

The polymerization yield depends on the purity of the metallocene in the catalyst; the metallocene according to the invention may be used as such or may have been subjected to a purification treatment beforehand.

The metallocene and cocatalyst may be suitably contacted therein prior to polymerization. The contact time is 1 to 60 minutes, preferably 5 to 20 minutes. The pre-contact concentration of the metallocene is 10 ⁻² to 10 ⁻⁸ mol / L.
10 ⁻³ mol / L. The pre-contacting is usually performed in the presence of a hydrocarbon solvent, optionally in the presence of a small amount of monomer.

The copolymerization of propylene and styrene is performed in the presence of a small amount of ethylene. In particular, the propylene concentration is 0.1 M to 13 M, the styrene concentration is 10 ⁻³ M to 9 M, the ethylene concentration is less than one tenth of the propylene concentration, and the concentration of the catalyst is 10 ⁻⁸ M to 10 ^−2. M. The polymerization temperature is from -30 ° C to + 150 ° C, preferably 0 ° C.
C. to 100C.

The copolymers of the present invention may be blended with other polymers, preferably with an isotactic propylene polymer.

Such a polymer blend can be produced by mechanical blending of the polymer, at least at a low temperature, preferably at the melting point of the polymer.

[0042] Alternatively, the blending can be performed in a manner of polymerization that can be performed in at least two successive steps. The polymer is produced in a separate, subsequent step, operating in each step except the first step, in the presence of the polymer formed in the previous step. The catalyst is
All steps may be the same or different. For example, a Ziegler-Natta catalyst can be used in the first step, while the homogeneous catalyst system can be used in a subsequent step.

The present invention also provides a functionalized copolymer. As noted above, the copolymers of the present invention are particularly useful for preparing functionalized copolymers that are technically important for improving adhesion to other materials and improving compatibility. In fact, the comonomer units of formula (1) can be functionalized by various free radical, anionic and cationic methods, as described in the publication of random copolymers of ethene and styrene or substituted styrene and in the patent literature. can do. For example, a benzylic proton can be oxidized, halogenated or metallized to form the desired functional group (COOH, CH ₂ X and CH ₂ Mt, respectively) attached to the phenyl ring.

In addition, benzylic protons can be interconverted into stable anionic initiators for graft polymerization. In particular, the metallized polymer (primarily lithiated) is treated with an inert organic diluent prior to the addition of monomers such as styrene, substituted styrene, vinyl acetate, methyl acrylate, methyl methacrylate, acrylonitrile. Can be suspended therein. This method is particularly relevant for the preparation of graft copolymers that provide polystyrene branches to an isotactic polypropylene backbone.

Another object of the invention is a graft copolymer consisting of an isotactic-polypropylene-based copolymer as backbone. Examples of graft copolymers of the present invention are polystyrene or polyvinyl acetate or polymethacrylate or polymethyl methacrylate or polyacrylonitrile grafted on isotactic polypropylene.

The graft copolymer can be obtained by the above method. These graft copolymers are primarily useful as compatibilizers in the manufacture of usually incompatible polymer blends or alloys. Examples of polymers that are blended with a propylene polymer in the presence of a graft copolymer are polystyrenes, polyethers, polyacrylates such as polymethyl acrylate.

The following examples illustrate the invention but do not limit its scope.

Example 1 Under a nitrogen atmosphere, styrene (30 mL) and methylalumoxane (MAO) (300 mg) were introduced in this order into a three-neck 100 mL Pyrex (registered trademark) glass flask kept at −25 ° C. After removing the nitrogen, the liquid phase is saturated by bubbling a propylene / ethylene mixture (20/1 mol / mol) at normal pressure and flowing at 0.3 L / min.

The reaction is started by injecting 3 mg of rac-ethylene-bis (1-indenyl) ZrCl ₂ catalyst dissolved in 2 mL of anhydrous toluene into the flask.

After a reaction time of 4 hours, the polymer formed is converted to ethanol 2 acidified with HCl.
Coagulate in 00 mL, filter and dry in a vacuum oven. The yield is about 120 mg.

From the ¹³ C-NMR analysis (FIGS. 1 and 1B), the product showed 76 mol% of propylene units, 12 mol% of styrene units and 12 mol% of linked ethylene units (X _S = 0.12). ), While no large blocks of styrene units are observed. FIG. 1B shows that the intensity of the resonance signal at 30.3 ppm is almost six times weaker,
Approximately 41 times less intense than the resonance signal at 4.6, 44.8, 46.9 ppm [all signals attributable to bonding between different monomer units], approximately 41 attributable to the styrene-styrene sequence.
The ppm resonance signal is shown. This fact confirms the statistical properties of the product obtained.

From the differential calorimetry analysis performed at a scan rate of 10 K / min, the polymer was found to be 79 ° C. (△
The melting point of the H _f = 10J / g) and

(Equation 4) There is a feature. The weight average molecular weight measured by gel permeation chromatography is 3 × 10 ³ u
. m. a. It is.

Comparative Example 1 Propylene-styrene polymerization is carried out with the same type of catalyst system as described in the Arai et al. Patent cited above. Under a nitrogen atmosphere, toluene (30 mL), styrene (5 mL) and methylalumoxane (MAO) were placed in a 100 mL Pyrex glass three-necked flask maintained at 50 ° C.
) (600 mg) and triisobutylaluminum (0.4 mL). After removing the nitrogen, the liquid phase was bubbled with propylene at normal pressure, 0.3 L / min.
To saturate.

The reaction is started by injecting 5 mg of rac-isopropylidene-bis (1-indenyl) ZrCl ₂ catalyst dissolved in 2 mL of anhydrous toluene into the flask.

After a reaction time of 4 hours, the polymer formed is converted to ethanol 2 acidified with HCl.
Coagulate in 00 mL, filter and dry in a vacuum oven. The yield is about 320 mg.

From the ¹³ C-NMR analysis (FIGS. 2 and 2B), the product results from 13 mol% of styrene units. FIG. 2B shows that the styrene content is lower than in the product of Example 1 (
(8% vs. 12%), despite the fact that it has an intensity comparable to the resonance signal attributable to the bond between the different monomer units in the region of 30-38 ppm and 41 and 43 ppm attributable to the styrene-styrene sequence. The resonance signal is shown. This fact confirms the presence of blocks in the polymer.

Example 2 The catalyst system, operating method and reaction conditions used are the same as those of Example 1, except for the amounts of styrene (10 mL) and toluene (20 mL) used. The yield is about 200 mg. ^{From 13} C-NMR analysis, the product results from 88 mol% of propylene units, 6 mol% of styrene units and 6 mol% of linked ethylene units (X _S = 0.06).

From differential calorimetry analysis (DSC), the polymer had a melting point of 103 ° C. (ΔH _f = 24 J / g) and

(Equation 5) There is a feature.

Example 3 The reaction was carried out at 0 ° C. with 50 mL of toluene, 3.2 mL of styrene, 0.9 g of M
In a 250 mL autoclave containing AO and 9 mg of the same catalyst used in Examples 1 and 2, a gaseous mixture of ethylene / propylene (1/4 mol / mol) is fed at 2 atm.

The reaction is stopped after 1 hour and about 600 mg of product are obtained (conversion <5%).
). ^{According to 13} C-NMR analysis, the product had a content of ethylene units of 7%, and a sequence of ethylene units close to the sequence of ethylene units (4%) consisting of styrene units (3%) and propylene units. Dispensed, but characterized by a content of styrene units of 3 mol% (X _s = 0.03).

The melting point of the polymer is 124 ° C. (ΔH _f = 53 J / g)

(Equation 6) It is.

[0062] Homogeneous distribution of the comonomer is confirmed by extraction tests with hydrocarbon solvents: the polymer is completely soluble in boiling hexane and completely insoluble in boiling ethyl ether.

Example 4 Under a nitrogen atmosphere, toluene (28 mL), p-methylstyrene (2 mL) and methylalumoxane (MAO) (460 mg) were introduced into a 100 mL Pyrex glass three-necked flask kept at −25 ° C. in this order. I do. After removing the nitrogen, the liquid phase is saturated by bubbling a propylene / ethylene mixture (124/1 mol / mol) at normal pressure and flowing in at 0.3 L / min.

The reaction is started by injecting 6 mg of rac-ethylene-bis (1-indenyl) ZrCl ₂ catalyst dissolved in 2 mL of anhydrous toluene into the flask.

After a reaction time of 3 hours, the polymer formed is converted to ethanol 2 acidified with HCl.
Coagulate in 00 mL, filter and dry in a vacuum oven. The yield is about 500 mg.

From the ¹³ C-NMR analysis, the polymer consists essentially of isotactic polypropylene, with 0.7 mol% of p-methylstyrene units and 0.9 mol% of ethylene units, of which 0.7% is p - coupling to methyl styrene unit, X _S = 0.07)
As a result.

From the differential calorimetry analysis performed at a scan rate of 10 K / min, the polymer was found to be 134 ° C. (
△ in H _f = 85J / g) melting point resulting in a feature. Isotactic polypropylene obtained under the same conditions as this catalyst system was 151
It is interesting to show a melting point in ° C. (ΔHf = 95 J / g).

Example 5 The catalyst system, operating method and reaction conditions used were divinylbenzene instead of p-methylstyrene, and the composition of the propylene / ethylene mixture was 75/1 mol /
Except for the mole, it is the same as that of Example 4. The yield is about 500 mg. ^{From 13} C-NMR analysis, the polymer consists essentially of isotactic polypropylene, resulting in 0.7 mol% of divinylbenzene units and 0.7 mol% of bound ethylene units (X _S = 0.007). Including.

From the differential calorimetric analysis performed at a scan rate of 10 K / min, the polymer was found to be 131 ° C. (
△ in H _f = 90J / g) melting point resulting in a feature.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) C08F 210: 02) (81) Designated country EP (AT, BE, CH, CY, DE, DK, ES, FI) , FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), AE, AU, AZ, BG, BR, CA, CN, CZ, HU, ID, IL, IN, JP, KR, KZ, MX, NO, PL, RO, RU, SG, SK, TM, TR, UA, US, UZ, VN, YU, ZA Domodossola, 90 (72) Inventor Isso, Lorella Italy, -84100 Salerno, Ai 84100 Via Paradiso, 17 (72) Inventor Sconi, Luigi Italy, Ai-44100 Ferrara, Via Alianuova, 56 / B F-term (reference) 4J026 AA13 BA05 BA18 BA20 BA27 BA31 4J028 AA00A AB00A AC27A AC28A BA00A BA01B BB00A BB01B BC25B EA01 A02A02A04 EB02 A04B04A CA05 DA41 FA10 [Continued Summary] A graft copolymer consisting of a ctic-polypropylene-based copolymer.

Claims (11)

[Claims] (1) Formula (1): Wherein R is hydrogen, a halide group or a hydrocarbon group optionally containing an atom selected from oxygen, nitrogen, sulfur, phosphorus and silicon, and n is an integer of 1 to 3. Resonant signals having a homogeneous distribution and resulting from bonds between different monomer units are 30, 34, 35, 45
And around 47 ppm, and 41 ppm and styrene around 44 to 46 ppm.
An isotactic-polypropylene-based copolymer having a ¹³ C-NMR spectrum exhibiting an intensity at least twice as high as the resonance signal attributable to the styrene sequence. 2. The copolymer according to claim 1, wherein the content of the repeating unit of the formula (1) ranges from 0.1 to 30% by weight. 3. The copolymer of claim 1 having a degree of polymerization of at least 50. 4. The copolymer of claim 1 wherein R is selected from linear or branched C ₁ -C ₂₀ alkyl groups, C ₃ -C ₂₀ cycloalkyl groups and C ₆ -C ₂₀ aryl. The alkyl group may be a saturated or unsaturated group. 5. The copolymer of claim 4, wherein R is selected from methyl, ethyl, isopropyl, vinyl and allyl groups. 6. The copolymer of claim 1 wherein the R substituent comprises a functional group. 7. The copolymer of claim 1, wherein the content of meso dyad (m) is higher than 80%. 8. The process for producing a copolymer according to claim 1, which is carried out in the presence of a homogeneous catalyst system comprising a metallocene compound and a cocatalyst. 9. A functionalized copolymer obtained from the isotactic-polypropylene-based copolymer of claim 1. 10. A graft copolymer comprising the isotactic-polypropylene-based copolymer of claim 1 as a backbone. 11. Graft polymerized to isotactic polypropylene,
The graft copolymer of claim 10, wherein the graft copolymer is selected from polystyrene or polyvinyl acetate or polymethacrylate or polymethyl methacrylate or polyacrylonitrile.