Patent Description:
Polymer compositions that can be used to modify bitumen, are already known in the art.

Published European patent application <CIT> describes polymer compositions developed to be used in roofing applications. Said polymer compositions comprise two fractions, one of which is made up of a propylene homopolymer, and the other of a propylene-ethylene copolymer.

According to said patent application, the polymer compositions with the best properties for the use in bituminous mixtures for roofing must have an intrinsic viscosity (I. ) ranging from <NUM> to <NUM> dl/g for both the above mentioned polymer fractions.

Published European patent application <CIT> describes mixtures of bitumen and polymer compositions containing:.

Such compositions achieve an improved set of properties, in particular flexibility at low temperature, resistance to penetration and softening, and ductility.

<CIT> relates to a mixture comprising a polymer composition a bitumen A and a polymer composition B comprising (I) a butene polymer and II an heterophasic polyolefin composition. There are several differences with the claimed invention.

The applicant found that the modulus, and tensile properties of a bitumen composition can be improved by using a particular polymer compositions.

Object of the present disclosure is a mixture comprising:.

Component (A) preferably has the melt flow rate (<NUM>/<NUM>) ranging between <NUM> and <NUM>/<NUM>; more preferably between <NUM> and <NUM>/<NUM>.

Components (A)+ (B) blended together have the melt flow rate (<NUM>/<NUM>) comprised between <NUM> and <NUM>/<NUM>. preferably between <NUM> and <NUM>/<NUM>; more preferably between <NUM> and <NUM>/<NUM>.

Preferably component B) has a density (determined according to ISO <NUM> at <NUM>) of from <NUM> to <NUM>/cm<NUM>. Component B) is an ethylene copolymer containing C<NUM>-C<NUM> alpha-olefin derived units. Specific examples of such alpha-olefin comonomers are propylene, <NUM>-butene, <NUM>-pentene, <NUM>-methyl-<NUM>-pentene, <NUM>-hexene and <NUM>-octene; <NUM>-butene <NUM>-hexene and <NUM>-octene being preferred; <NUM>-butene being the most preferred.

Preferably the component T2) has a melt flow rate (<NUM>/<NUM>) comprised between <NUM> to <NUM>/<NUM> preferably from <NUM> to <NUM>/<NUM>; even more preferably from <NUM> to <NUM>/<NUM>.

Preferably, the component T2) has an intrinsic viscosity [η] (measured in tetrahydronaphthalene at <NUM>) of the xylene soluble fraction at <NUM> comprised between <NUM> to <NUM> dl/g preferably the intrinsic viscosity is comprised between <NUM> and <NUM> dl/g; more preferably the intrinsic viscosity is comprised between <NUM> and <NUM> dl/g.

For the present disclosure the term "copolymer" means polymers containing two kinds of comonomers such as propylene and ethylene or ethylene and <NUM>-butene.

Useful bitumens (T1) include solid, semi-solid or viscous distillation residues of the petroleum refinery process, consisting predominantly of high molecular weight hydrocarbons, the structure of which can be partially altered, for example by oxidation.

It has been found that the component T2) can be prepared by a sequential polymerization, comprising at least three sequential steps, wherein components (A), (B) and (C) are prepared in separate subsequent steps, operating in each step, except the first step, in the presence of the polymer formed and the catalyst used in the preceding step. The catalyst is added only in the first step, however its activity is such that it is still active for all the subsequent steps.

The polymerization, which can be continuous or batch, is carried out following known techniques and operating in liquid phase, in the presence or not of inert diluent, or in gas phase, or by mixed liquid-gas techniques. It is preferable to carry out the polymerization in gas phase.

Reaction time, pressure and temperature relative to the polymerization steps are not critical, however it is best if the temperature is from <NUM> to <NUM>. The pressure can be atmospheric or higher.

The regulation of the molecular weight is carried out by using known regulators, hydrogen in particular.

The said polymerizations are preferably carried out in the presence of a Ziegler-Natta catalyst. Typically, a Ziegler-Natta catalyst comprises the product of the reaction of an organometallic compound of group <NUM>, <NUM> or <NUM> of the Periodic Table of elements with a transition metal compound of groups <NUM> to <NUM> of the Periodic Table of Elements (new notation). In particular, the transition metal compound can be selected among compounds of Ti, V, Zr, Cr and Hf and is preferably supported on MgCl<NUM>.

Particularly preferred catalysts comprise the product of the reaction of said organometallic compound of group <NUM>, <NUM> or <NUM> of the Periodic Table of elements, with a solid catalyst component comprising a Ti compound and an electron donor compound supported on MgCl<NUM>.

Preferred organometallic compounds are the aluminum alkyl compounds.

Thus, in a preferred embodiment, the polymer composition B) of the present invention is obtainable by using a Ziegler-Natta polymerization catalyst, more preferably a Ziegler-Natta catalyst supported on MgCl<NUM>, even more preferably a Ziegler-Natta catalyst comprising the product of reaction of:.

The solid catalyst component (<NUM>) contains as electron-donor a compound generally selected among the ethers, ketones, lactones, compounds containing N, P and/or S atoms, and mono- and dicarboxylic acid esters.

Catalysts having the above-mentioned characteristics are well known in the patent literature; particularly advantageous are the catalysts described in <CIT> and <CIT>.

Particularly suited among the said electron-donor compounds are phthalic acid esters, preferably diisobutyl phthalate, and succinic acid esters.

Suitable succinic acid esters are represented by the formula (I):
<CHM>
wherein the radicals R<NUM> and R<NUM>, equal to or different from each other, are a C<NUM>-C<NUM> linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms; the radicals R<NUM> to R<NUM> equal to or different from each other, are hydrogen or a C<NUM>-C<NUM> linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms, and the radicals R<NUM> to R<NUM> which are joined to the same carbon atom can be linked together to form a cycle.

R<NUM> and R<NUM> are preferably Ci-Cs alkyl, cycloalkyl, aryl, arylalkyl and alkylaryl groups. Particularly preferred are the compounds in which R<NUM> and R<NUM> are selected from primary alkyls and in particular branched primary alkyls. Examples of suitable R<NUM> and R<NUM> groups are methyl, ethyl, n-propyl, n-butyl, isobutyl, neopentyl, <NUM>-ethylhexyl. Particularly preferred are ethyl, isobutyl, and neopentyl.

One of the preferred groups of compounds described by the formula (I) is that in which R<NUM> to R<NUM> are hydrogen and R<NUM> is a branched alkyl, cycloalkyl, aryl, arylalkyl and alkylaryl radical having from <NUM> to <NUM> carbon atoms. Another preferred group of compounds within those of formula (I) is that in which at least two radicals from R<NUM> to R<NUM> are different from hydrogen and are selected from C<NUM>-C<NUM> linear or branched alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or alkylaryl group, optionally containing heteroatoms. Particularly preferred are the compounds in which the two radicals different from hydrogen are linked to the same carbon atom. Furthermore, also the compounds in which at least two radicals different from hydrogen are linked to different carbon atoms, that is R<NUM> and R<NUM> or R<NUM> and R<NUM> are particularly preferred.

Other electron-donors particularly suited are the <NUM>,<NUM>-diethers, as illustrated in published European patent applications <CIT> and <CIT>.

As cocatalysts (<NUM>), one preferably uses the trialkyl aluminum compounds, such as Al-triethyl, Al-triisobutyl and Al-tri-n-butyl.

The electron-donor compounds (<NUM>) that can be used as external electron-donors (added to the Al-alkyl compound) comprise the aromatic acid esters (such as alkylic benzoates), heterocyclic compounds (such as the <NUM>,<NUM>,<NUM>,<NUM>-tetramethylpiperidine and the <NUM>,<NUM>-diisopropylpiperidine), and in particular silicon compounds containing at least one Si-OR bond (where R is a hydrocarbon radical).

Examples of the said silicon compounds are those of formula R<NUM>aR<NUM>bSi(OR<NUM>)c, where a and b are integer numbers from <NUM> to <NUM>, c is an integer from <NUM> to <NUM> and the sum (a+b+c) is <NUM>; R<NUM>, R<NUM> and R<NUM> are alkyl, cycloalkyl or aryl radicals with <NUM>-<NUM> carbon atoms optionally containing heteroatoms.

Useful examples of silicon compounds are (tert-butyl)<NUM>Si(OCH<NUM>)<NUM>, (cyclohexyl)(methyl)Si (OCH<NUM>)<NUM>, (phenyl)<NUM>Si(OCH<NUM>)<NUM> and (cyclopentyl)<NUM>Si(OCH<NUM>)<NUM>.

The previously said <NUM>,<NUM>- diethers are also suitable to be used as external donors. In the case that the internal donor is one of the said <NUM>,<NUM>-diethers, the external donor can be omitted.

The catalysts may be precontacted with small quantities of olefin (prepolymerization), maintaining the catalyst in supension in a hydrocarbon solvent, and polymerizing at temperatures from room to <NUM>, thus producing a quantity of polymer from <NUM> to <NUM> times the weight of the catalyst.

The operation can also take place in liquid monomer, producing, in this case, a quantity of polymer up to <NUM> times the weight of the catalyst. the polyolefin compositions T2) can also prepared as a physical blend of the separately-prepared components rather than as a reactor blend.

Moreover the mixture of the present disclosure may contain at least one other type of polymer, hereinafter identified as component (T3), in addition to the polymer composition (T2).

For example, the mixture may comprise, as component (T3), one or more olefinic or nonolefinic polymers. In particular, such additional polymers (T3) can be selected from the group consisting of amorphous or atactic polymers (in particular amorphous polyolefins such as amorphous polypropylene), styrene-butadiene-styrene (SBS) copolymers, ethylene polyvinyl acetate, low or high density polyethylene, and other polyolefins, in particular isotactic polypropylene and ethylene-propylene random copolymers.

Generally the said additional polymers (T3) are added, for example, in quantities greater than or equal to <NUM>%, preferably from <NUM> to <NUM>%, more preferably from <NUM> to <NUM>% by weight with respect to the weight of the mixture. Even when the said additional polymers are present, the total quantity of component T2 and T3, in other words the amount of T2+T3, in the bituminous mixture is less than or equal to <NUM>%, preferably <NUM>% by weight with respect to the total weight of the mixture.

The polymer composition (T2) and all the other described components are incorporated in the bitumen according to known methods.

Preferably the mixing process is carried out at a temperature from <NUM> to <NUM>; more preferably from <NUM> to <NUM>.

The mixtures of the present disclosure can be used in the commonly known applications of polymer modified bitumens, in particular for road paving and in the preparation of roofing membranes.

The following examples are given in order to illustrate, but not limit the present disclosure.

Measured according to ISO <NUM> at <NUM> with a load of <NUM>, unless otherwise specified.

The sample is dissolved in tetrahydronaphthalene at <NUM> and then is poured into the capillary viscometer. The viscometer tube (Ubbelohde type) is surrounded by a cylindrical glass jacket; this setup allows temperature control with a circulating thermostated liquid. The downward passage of the meniscus is timed by a photoelectric device.

The passage of the meniscus in front of the upper lamp starts the counter which has a quartz crystal oscillator. The meniscus stops the counter as it passes the lower lamp and the efflux time is registered: this is converted into a value of intrinsic viscosity through Huggins' equation (<NPL>) provided that the flow time of the pure solvent is known at the same experimental conditions (same viscometer and same temperature). One single polymer solution is used to determine [η].

<NUM>C NMR spectra of base polymers and their fractions were acquired on a Bruker AV600 spectrometer equipped with cryo probe, operating <NUM> MHz in the Fourier transform mode at <NUM>. The peak of the S□□ carbon (nomenclature according C. Harrington and C. Wilkes, Macromolecules, <NUM>, <NUM>, <NUM> (<NUM>)) was used as internal reference at <NUM> ppm. About <NUM> of sample were dissolved in <NUM> of <NUM>,<NUM>,<NUM>,<NUM> tetrachloro ethane d2 at <NUM>. Each spectrum was acquired with a <NUM> ° pulse, <NUM> seconds of delay between pulses and CPD to remove <NUM>-13C coupling. <NUM> transients were stored in <NUM> data points using a spectral window of <NUM>. The assignments of the spectra were made according to <NPL>) and <NPL>).

The triad distribution was obtained using the following relations:
<MAT>
<MAT>
<MAT>
<MAT>
<MAT>
<MAT>
<MAT>
<MAT>
wherein
<MAT>
and wherein X can be propylene (P) or <NUM>-butene (B), and I<NUM> to I<NUM> are the areas of the corresponding carbon atoms as reported below (only selected triads and assignements being reported):.

The molar content of ethylene (E), of propylene (P) and of <NUM>-butene (B) is obtained from triads using the following relations:
<MAT>
<MAT>
<MAT>.

Other comonomers can be easily determined by using NMR procedures known in the art.

The solid catalyst component used in polymerization is a Ziegler-Natta catalyst component supported on magnesium chloride, containing titanium and diisobutylphthalate as internal donor, prepared as follows. An initial amount of microspheroidal MgCl2·<NUM>. 8C2H5OH was prepared according to the method described in Example <NUM> of <CIT> but operating at <NUM>,<NUM> rpm instead of <NUM>,<NUM>. The so obtained adduct was then subject to thermal dealcoholation at increasing temperatures from <NUM> to <NUM> operating in nitrogen current until the molar alcohol content per mol of Mg is <NUM>. Into a <NUM> four-necked round flask, purged with nitrogen, <NUM> of TiCl4 were introduced at <NUM>. While stirring, <NUM> grams of the microspheroidal MgCl2·<NUM>. 16C2H5OH adduct (prepared as described above) were added. The temperature was raised to <NUM> and kept at this value for <NUM> minutes. During the temperature increase, an amount of diisobutylphthalate was added such as to have a Mg/ diisobutylphthalate molar ratio of <NUM>. After the mentioned <NUM> minutes, the stirring was stopped, the liquid siphoned off and the treatment with TiCl4 was repeated at <NUM> for <NUM> hour in the presence of an amount of diisobutylphthalate such as to have a Mg/ diisobutylphthalate molar ratio of <NUM>. After that time the stirring was stopped, the liquid siphoned off and the treatment with TiCl4 was repeated at <NUM> for <NUM>. After sedimentation and siphoning at <NUM> the solid was washed six times with anhydrous hexane (<NUM> x <NUM>) at <NUM>.

Before introducing it into the polymerization reactors, the solid catalyst component described above is contacted at <NUM> for <NUM> minutes with aluminum triethyl (TEAL) and dicyclopentyldimethoxysilane (DCPMS), in a TEAL/DCPMS weight ratio equal to about <NUM> and in such quantity that the TEAL/solid catalyst component weight ratio be equal to <NUM>.

The catalyst system is then subjected to prepolymerization by maintaining it in suspension in liquid propylene at <NUM> for about <NUM> minutes before introducing it into the first polymerization reactor.

The polymerization is carried out in continuous in a series of three gas-phase reactors equipped with devices to transfer the product from the first reactor to the second one. Into the first gas phase polymerization reactor a propylene-based polymer (i) is produced by feeding in a continuous and constant flow the prepolymerized catalyst system, hydrogen (used as molecular weight regulator) and propylene all in the gas state. The propylene-based polymer (i) coming from the first reactor is discharged in a continuous flow and, after having been purged of unreacted monomers, is introduced, in a continuous flow, into the second gas phase reactor, together with quantitatively constant flows of hydrogen and ethylene, all in the gas state. In the second reactor a copolymer of ethylene (ii) is produced. The product coming from the second reactor is discharged in a continuous flow and, after having been purged of unreacted monomers, is introduced, in a continuous flow, into the third gas phase reactor, together with quantitatively constant flows of hydrogen, ethylene and propylene all in the gas state. In the third reactor an ethylene-propylene polymer (iii) is produced. Polymerization conditions, molar ratio of the reactants and composition of the copolymers obtained are shown in Table <NUM>. The polymer particles exiting the third reactor are subjected to a steam treatment to remove the reactive monomers and volatile substances, and then dried. Thereafter the polymer particles are mixed with a usual stabilizing additive composition in a twin screw extruder Berstorff ZE <NUM> (length/diameter ratio of screws: <NUM>) and extruded under nitrogen atmosphere in the following conditions:.

The stabilizing additive composition is made of the following components:.

all percent amounts being referred to the total weight of the polymer and stabilizing additive composition.

The said Irganox® <NUM> is <NUM>,<NUM>-bis[<NUM>-[,<NUM>-bis(<NUM>,<NUM>-dimethylethyl)-<NUM>-hydroxyphenyl)-<NUM>-oxopropoxy]methyl]-<NUM>,<NUM>-propanediyl-<NUM>,<NUM>-bis(<NUM>,<NUM>-dimethylethyl)-<NUM>-hydroxybenzene-propanoate, while Irgafos® <NUM> is tris(<NUM>,<NUM>-di-tert. -butylphenyl)phosphite. The characteristics relating to the polymer composition, reported in Table <NUM>.

Comparative example <NUM> is an heterophasic copolymer having an homopolymer matrix and a propylene ethylene rubber phase. The feature of the polymer of comparative example <NUM> are reported on table <NUM>.

The polymer of example <NUM> and comparative example <NUM> have been blended with bitumen. The blends contain <NUM>% of the polymers of example <NUM> (T2) and comparative example <NUM> (T2) and <NUM>% of bitumen (T1). The two composition are marked as B1 e B2.

<NUM>% of B1 and B2 has been mixed with sand, stone and gravel to obtain asphalt. A black sample obtained by using bitumen (T1) without T2 and sand, stone and gravel has been produced (sample C1).

The feature of the asphalt obtained has measured and the results are reported on table <NUM>.

CTI, Coefficient of Indirect Tensile strength, and RT Indirect Tensile strength, has been measured according to EN <NUM>-<NUM> on a sample having a diameter of <NUM>. From table <NUM> the superior features of the asphalt obtained according to the present invention clearly result.

The polymer of example <NUM> have been blended with bitumen. The blends contain 4wt% and 5wt% of the polymers of example <NUM> (T2) T1 is the bitumen without additives. The compositions are marked as B3, B4,
The features of the obtained bitumen are reported on table <NUM>.

The properties of the polymer composition/bitumen mixtures were determined as follows.

The R&B test determines the temperature at which a layer of bitumen, in a brass ring, experiences a certain deformation under the weight of a steel ball as the temperature rises.

The penetration test determines depth, measured in <NUM>/<NUM>, to which a <NUM> needle penetrates in <NUM> seconds into the bitumen at a temperature of <NUM>.

Claim 1:
A mixture comprising:
T1) from <NUM> wt% to <NUM> wt% of bitumen , and
T2) from <NUM> wt% to <NUM> wt% of polymer composition comprising the following components,
A) <NUM>-<NUM>% by weight of a propylene homopolymer or a propylene ethylene copolymer containing <NUM>% by weight or more of propylene units; component A) containing <NUM> % by weight or less of a fraction soluble in xylene at <NUM> (XSa), both the amount of propylene units and of the fraction XSA being referred to the weight of A);
B) <NUM>-<NUM>% by weight; of a copolymer of ethylene and a C<NUM>-C<NUM> alpha-olefin containing from <NUM> % to <NUM> % by weight of alpha-olefin units and containing <NUM> % by weight or less; of a fraction soluble in xylene at <NUM> (XSB), both the amount of alpha-olefin units and of the fraction XSB being referred to the weight of (B); and
C) <NUM>-<NUM>% by weight of a copolymer of ethylene and propylene containing from <NUM> % to <NUM> % by weight of ethylene units and containing from <NUM> % to <NUM>% by weight of a fraction soluble in xylene at <NUM> (XSc), both the amount of ethylene units and of the fraction XSc being referred to the weight of (C);
the amounts of (A), (B) and (C) being referred to the total weight of (A) + (B) + (C), the sum of the amount of (A) + (B) + (C) being <NUM>;
the amounts, wt%, of T1 +T2 being <NUM> wt%.