Multimodal polyethylene resin for tubes, obtained using single-site catalyst on metal

FIELD: chemistry.

SUBSTANCE: composition contains a multimodal polyethylene basic resin obtained during polymerisation of at least one of fractions (A) and (B) in the presence of a single-site catalyst (SSC) on a metal. The fraction (A) in the composition is an ethylene copolymer and fraction (B) is an ethylene homo- or copolymer. Fraction (A) has lower molecular weight than fraction (B). The basic resin has density lower than 940 kg/m3, melt flow rate (MFR2) at 190°C/2.16 kg from 0.001 to 10 g/10 min and the composition has bending modulus between 300 and 820 MPa.

EFFECT: polyethylene composition has good processability during production and flexibility which is sufficient for easy handling, and meets PE63 class requirements or higher for pressure.

13 cl, 1 tbl, 2 ex

 

The present invention relates to a polyethylene composition comprising a polyethylene resin produced in the polymerization process in the presence of a catalyst with a single center of polymerization on the metal (SSC). Moreover, the present invention relates to the use of such a polyethylene composition for the production of pipes, in particular a pressure pipe made from a plastic composition.

Pipes, in particular pressure pipes, used in various purposes such as transportation of drinking water, wastewater, as well as in various industrial purposes, for transportation of gas and so on.

Depending on the strength of the polymer polyethylene pipes for pressure systems can be classified into several categories, such as PE63, PE80 or PE100. The higher the numerical value, the longer the service life at high pressure.

Currently, the best plastic resin for pressure pipes produced by the multi-stage process in the presence of catalysts of the Ziegler-Natta. Density values such polyethylene resins is high enough to ensure that the produced pipe high pressure resistance, However, the high density results in high rigidity, which is a disadvantage, for example, when installing pipes.

In the late 80s Kaminsky (Kaminsky) and others to depict Avila metallocene catalyst type catalyst with a single center of polymerization on the metal. There was a lively study of metallocene catalysts, but until the introduction of polyolefin resins obtained by using metallocene catalysts, remains insignificant. The main areas of use of catalysts with a single center of polymerization on the metal are films or coatings applied by extrusion, as described for example in WO 03/066699. The films described herein have excellent mechanical properties and exceptional integrity.

However, it is known that the catalytic activity of catalysts with a single center of polymerization on the metal is moderate and the highest activity was achieved in the range of low and medium density.

To meet the requirements RE towards multimodal polyolefin resins made using the traditional catalyst of the Ziegler-Natta, their density must be at least 940 kg/m3and to meet the requirements of PE100, the density must exceed at least 945 kg/m3. Resin for pressure pipes obtained by using catalysts with a single center of polymerization on the metal known in the art, as described, for example, in WO 02/34829, also have a higher density of 940 kg/m3. The result of the application of such resins high density is that the flexibility of manufacturing olenych of these pipes is quite low.

Moreover, for the production of pressure pipes it is necessary to apply a polyethylene composition had such speed melt flow and molecular weight distribution, which could ensure good workability of the composition in the extrusion process.

For this reason, the aim of the present invention is to provide a polyethylene composition for the manufacture of pipes, in particular a pressure pipe, which simultaneously have good machinability in the production and flexibility for easy handling, and meet the requirements of class PE63 or higher pressure.

It was unexpectedly discovered that such a polyethylene composition can be obtained, if its production is used catalyst with a single center of polymerization on the metal, and the resin composition has a density lower than 940 kg/m3.

Therefore, the present invention provides a polyethylene composition comprising a polyethylene core resin, which contains

A. a copolymer of ethylene as a fraction (A) and

B. Homo - or copolymer of ethylene as a fraction (B),

moreover, the fraction (A) has a lower molecular weight than fraction (B), where the PE the main resin can be obtained by the polymerization method, in which the polymerisation of at least one of the fractions (A) and (B) note the following catalyst with a single center of polymerization on the metal (SSC), and the main resin has:

(i) a density less than 940 kg/m3and

(ii) the rate of flow of the melt (CTP2) at 190°C/2,16 kg) from 0.01 to 10 g/10 min, and

the composition has

(iii) bending modulus from 300 to 820 MPa.

As shown below, the present invention enables to produce a more flexible pipes meet the requirements of resistance to high pressure.

For this reason, for example, the compositions of the present invention allow the manufacture of flexible tubes which are easier to bend and therefore easier to twist into a roll. This gives the advantage that the installation of pipes much easier.

At the same time have such high resistance that the pipes can be used in areas where traditionally only used pipes made from polyolefin compositions of higher density.

The term "principal resin" refers to the combination of the polymeric components of the polyethylene compositions of the present invention, is usually component of at least 90 wt.% of the total weight of the composition. Preferably, the main resin consists of fractions (A) and (B), and optionally contains forprimary fraction in an amount up to 20 wt.%, preferably up to 10 wt.%, more preferably up to 5 wt.% from the total mass of the resin base.

The basic density of the resin contained in the polyethylene composition is according to the present invention, measured according to ISO 1183, is in the middle range, i.e. less than 940 kg/m3more preferably in the range from 910 to less than 940 kg/m3even more preferably in the range of from 915 to less than 940 kg/m3and most preferably in the range from 920 to less 939 kg/m3.

Despite the fact that the density of the resin base compared to traditional resins 5-10 kg/m3below, pipes made from compositions of the present invention, correspond to classes of high pressure pipes.

The rate of flow of the melt (CTP) and the ratio of flow rates (swaps) are important characteristics of the polyethylene resin base, because CTP and GSP are the yield and thus the workability of the polymer. The higher the flow velocity of the melt, the lower the viscosity of the polymer. CTP is measured according to ISO 1133, expressed in g/10 min and is determined at the temperature of 190°C and different loads, such as 2,16 kg (CTP2; ISO 1133), 5,0 kg (CTP5; ISO 1133) or 21.6 kg (CTP21; ISO 1133). The ratio of flow rates (cap) represents the ratio between the Pload 1and Pload 2i.e. BSA21/5means the ratio between CTP21and CTP5.

The PE the main resin of the present invention preferably has a CTP2from 0.01 to 5.0 g/10 min, more preferably from 0.02 to 1.0 g/10 m is n and most preferably from 0.10 to 0.50 g/10 min.

The modulus of elasticity (young's modulus, E-module) is determined according to ISO 527. The polyethylene composition of the present invention preferably has a modulus of elasticity of from 400 to 900 MPa, more preferably from 425 to 850 MPa, and most preferably from 450 to 800 MPa.

Moreover, it is preferable that the bending modulus polyethylene compositions ranged from 400 to less than 800 MPa, more preferably from 450 to 700 MPa, and most preferably from 450 to 650 MPa.

Test for impact strength according to Charpy at low temperature reflects the impact strength and, therefore, provides a method of evaluating the resistance to rapid crack propagation (RCP).

In a preferred variant embodiment of the present invention the polyethylene composition has an impact strength Charpy at 0°C, defined by ISO 179, at least 8 kJ/m2and more preferably at least 10 kJ/m2.

Resistance of polyethylene compositions to rapid crack propagation can also define a method called S4 (test steady state in a shorter program), developed at Imperial College, London, and is described in ISO 13477: 1977 (E). Pipe according to the present invention preferably reaches the critical temperature, i.e. the values of RCP-S4, +2°C or below, more preferably +1°C or below.

Resistance to slow most the of cracks can be determined according to ISO 13479: 1997, where determine the number of hours during which the pipe is notched stand at a certain temperature, a certain pressure to fracture.

The polyethylene composition of the pipe according to the present invention preferably shows according to ISO 1167 resistance to slow crack propagation when the ring voltage of 5.4 MPa and 80°C, preferably at least 165 hours, more preferably at least 500 hours, even more preferably at least 1000 hours and most preferably at least 4000 hours.

An additional important characteristic of the pipe is the nominal value of the rated voltage, which is voltage on the surface of the pipe, is designed so that the pipe is kept for 50 years without breaking, and which is determined at different temperatures in terms of the minimum long-term strength (MRS) according to ISO/TR 9080. So, MRS 8,0 means that this pipe is a pipe that can withstand the ring voltage at a rate of 8.0 MPa for 50 years at 20°C and similarly MRS 10,0 means that the pipe can withstand the ring voltage in the amount of 10 MPa for 50 years at 20°C.

The polyethylene composition of the pipe according to the present invention preferably has a nominal value of MRS at least 6,3, more preferably at least an 8.0, and most preferred is sustained fashion 10,0.

Index thinning under shear stress (SHI) is the ratio of the viscosities of polyethylene resin base at different shear stresses and may serve as an indicator of the width of the molecular weight distribution. According to the present invention for determining SHI polyethylene resin base applied shear stress of 2.7 kPa and 210 kPa and 5 kPa and 300 kPa. The definition and the measurement conditions are described in detail in WO 00/22040, page 8, line 29 to page 11 line 25.

The PE the main resin preferably has a SHI(of 2.7/210)less than 20, more preferably less than 15 and most preferably less than 10. The preferred range SHI(of 2.7/210)is the range from 1 to less than 20.

Also preferably SHI(5/300)is less than 35, more preferably less than 30 and most preferably less than 25. The preferred range SHI(5/300)is the range from 5 to less than 35.

It should be noted that the polyethylene composition of the present invention and, therefore, also made her pipes are characterized not only of the above characteristics, and the combination of them all, as defined in claim 1 of the claims. A unique combination of characteristics can be obtained a polymer composition for pipes with a performance of the highest quality in private is minute in relation to their flexibility, machinability, operational characteristics with respect to pressure, resistance to impact, resistance to fast and slow crack propagation.

In addition, it is important to pay attention to the importance of good machinability polyethylene compositions intended for the manufacture of pipes. To obtain good resistance to pressure and a low creep high molecular weight. Improved machinability is achieved with multimodal performance. This is achieved by the fact that in the composition used for pipes according to the present invention, there is at least one fraction of low molecular weight, provides good machinability and one fraction with high molecular weight that provides mechanical strength.

Typically, a "multimodal" is called a polyethylene composition comprising at least two polyethylene fractions, which were produced under different conditions of polymerization, which is a consequence of various (mass-average) molecular weight fractions. The prefix "multi" refers to the number of different polymer fractions that make up the composition. For example, a composition consisting only of the two factions, called "bimodal".

The shape of the curve of the molecular-mass distribution, i.e. the dependence of the mass fraction is Ricci polymer from its molecular weight, for such a multimodal polyethylene will show one or more maxima or at least wider in comparison with the curves for the individual fractions.

For example, if the polymer is produced sequential multistage manner, using serially arranged reactors and creating in each reactor, the different conditions, each fraction of polymer produced in each reactor will have its own molecular weight distribution and mass-average molecular weight. If for each polymer fixed curve of the molecular-mass distribution, the individual curves for these fractions are superimposed on the curve of the molecular-mass distribution for the resulting polymer product as a whole, forming as a result, as a rule, a curve with two or more distinct peaks.

The PE the main resin composition of the present invention is or multimodal, preferably bimodal polyethylene resin comprising at least two polyethylene fractions (A) and (B), where the fraction (A) has a lower molecular weight than fraction (B). The term molecular weight used herein, denotes a mass-average molecular mass Mw.

The PE the main resin of the present invention preferably has m LeCoultre weight distribution (MWD), defined as the ratio of mass-average molecular mass Mwand srednekamennogo molecular mass Mnfrom 5 to 25, more preferably from 5 to 20 and most preferably from 5 to 15.

Previously it was known that for the production of multimodal, in particular bimodal, olefinic polymers such as polyethylene main resin of the present invention, using two or more reactors or zones connected in series, as described in EP 517868, which is herein entered entirely by reference.

Main stage polymerization is preferably carried out by a combination of suspension and gas-phase polymerization. Suspension polymerization is preferably carried out in the so-called loop reactor. Optionally and preferably the main stage polymerization is preceded by terpolymerization, in which case most preferably is from 1 to 5 wt.% the total number of polymer. The prepolymer may be a Homo - or copolymer of ethylene.

If there is terpolymerization, in this case, the entire catalyst is preferably loaded into the first reactor for terpolymerization and terpolymerization spend in a variant of the suspension polymerization. Such polymerization leads to fewer fine inclusions, which could obra is to find in the subsequent reactors, and eventually to a more homogeneous product. Typically, this technology leads to a mixture of multimodal polymers during polymerization using the catalyst of the present invention using a catalyst with a single center of polymerization on the metal.

The catalyst with a single center of polymerization on the metal used in the examples according to the present invention has been described in EP 1462464, Example 5, the catalyst 3.

In the method according to the present invention for the production of resin base polymer composition of the present invention, at least a fraction (A) or fraction (B) obtained by polymerization reaction in the presence of a catalyst with a single center of polymerization on the metal. For example, fraction (A) or alternative (B) may be obtained in the presence of a catalyst with a single center of polymerization on the metal, and fraction (B) or alternative (A) may be obtained in the presence of a catalyst of Ziegler-Natta.

However, it is preferable that both fractions (A) and (B) were obtained in the presence of a catalyst with a single center of polymerization on the metal.

Moreover, preferably, fraction (A) and fraction (B) were polymerized in the presence of the same catalyst with a single center of polymerization on the metal.

In the production of polyethylene resin base according to the present invention the fraction (A) preferably p is get in a loop reactor at specific values of the hydrogen concentration, monomer and co monomer, temperature, pressure and so on.

Moreover, preferably, fraction (B) was obtained in the gas-phase reactor.

In addition, it is preferable that after polymerization, the fraction (A), including the catalyst was transferred into the reactor, preferably in a gas-phase reactor, where the fraction (B) obtained when other conditions.

The resulting end product consists of a homogeneous mixture of the polymers of the two main reactor and optionally a fraction of the prepolymer, the different curves of the molecular-mass distribution for these polymers together form a curve of the molecular mass distribution with a broad maximum or two maxima, i.e. the final product is a bimodal polymer mixture.

To make attainable thus the flexibility of the reaction conditions it is most preferable that the polymerization was carried out in the sequence of reactors: reactor terpolymerization/loop reactor/gas-phase reactor. Preferably the conditions of polymerization in the preferred three-stage method are chosen so that the fraction (A) was obtained in one stage, preferably the second reactor, while the fraction (B) was received on a different stage, preferably in the third reactor. The order of these stages, however, may be reversed.

According to the present invention, preferred is entrusted, to terpolymerization proceeded at a temperature of from 40 to 70°C, more preferably from 50 to 65°C and preferably at a pressure of from 50 to 70 bar, more preferably from 55 to 65 bar.

In the second reactor, the polymerization temperature is preferably from 60 to 100°C, more preferably from 70 to 90°C, and the pressure is preferably from 40 to 70 bar, more preferably from 50 to 60 bar.

In the third reactor temperature is preferably from 60 to 105°C, more preferably from 70 to 90°C, and the pressure is preferably from 10 to 40 bar, more preferably from 15 to 20 bar.

The mass ratio of fractions (A) and (B) is preferably from 60:40 to 40:60, more preferably from 55:45 to 45:55.

The present invention component (A) is a copolymer of ethylene and fraction (B) may be Homo - or copolymer of ethylene. Preferably, fraction (B) is a copolymer of ethylene.

The comonomers used in both fractions, may be the same or different.

As comonomers may apply different alpha-olefins with 4-20 carbon atoms, however, the comonomers are preferably chosen from the group of 1-butene, 1-penten, 4-methyl-1-penten, 1-hexene, 1-hepten, 1-octene, 1-mission 1-achozen. In particular, in a preferred variant embodiment of the co monomer is 1-butene and/or 1-hexene.

Preferably, fraction (B) before the hat is a copolymer of ethylene, and used by the co monomer is an alpha olefin with 4, more preferably 6 or more carbon atoms, more preferably 1-hexene or 1-octene.

At least one of the fractions (A) and (B) may also consist of ethylene and two or more different comonomers parts, for example, may consist of terpolymer.

If the composition of the present invention contains terpolymer, preferably it is terpolymers ethylene and C4-C12alpha-olefin comonomers, preferably fraction (B) is terpolymers.

The number of co monomer used in fraction (A)preferably is 0.1 to 3.0 mol.%, more preferably of 0.2 to 2.0 mol.%, even more preferably 0.5 to 1.5 mol.%.

The number of co monomer used in fraction (B), preferably 0.1 to 2.0 mol.%, more preferably 0.1 to 1.5 mol.%, even more preferably 0.2 to 1.0 mol.%.

Moreover, preferably, fraction (A) had a density 920-962 kg/m3more preferably 925-945 kg/m3most preferably 925-940 kg/m3.

Additionally, the flow rate of the melt CTP2(190°C/2,16 kg) fraction (A) is preferably 10-300 g/10 min, more preferably 50-140 g/10 minutes

The polyethylene composition of the present invention may also contain additives such as processing AIDS, antioxidant is Lanta, pigments, UV stabilizers and the like. Typically, the amount of such additives is 10 wt.% or less relative to the entire composition.

The present invention also relates to a pipe, in particular to a pressure tube containing the above polyethylene composition, as well as to the use of such compositions for the manufacture of pipes, in particular pressure pipes.

The pipe according to the present invention can be produced by any conventional method, preferably by extrusion of the polyolefin composition in the extruder. This technology is well known to specialists in this field of technology.

The pipe according to the present invention exhibits good resistance to loads and high flexibility.

Methods and examples

The rate of flow of the melt (CTP)

CTP is determined according to ISO 1133 and is expressed in g/10 min. For polyethylene resins used a temperature of 190°C. CTP is determined at different loadings such as 2,16 kg (CTP2), 5 kg (CTP5) or 21.6 kg (CTP21).

Molecular mass

The mass-average molecular mass Mwand molecular weight distribution (MWD=Mw/Mnwhere Mnrepresents srednecenovogo molecular weight, a Mw- mass-average molecular weight) is measured on the basis of ISO 1014-4:2003. Used appliance Waters 150CV plus, column 3×HT&E styragel, Waters, (divinyl ensol) and trichlorobenzene (TCB) as solvent at 140°C. Columns were calibrated using universal calibration standards PS with narrow MWD (constant Mark Houwings K: 9,54*10-5and a: 0,725 for PS and K: 3,92*10-4and a: 0,725 for PE). The relation of Mwand Mnis a measure of the width of the distribution, because each of the terms is influenced by the opposite ends of a "set".

Rapid crack propagation (S4)

Resistance to rapid crack propagation (RCP) pipe is determined according to ISO 13477 (E). By way of RCP-S4 have a tube having a longitudinal length no less than 7 pipe diameters. The tube outer diameter is about 110 mm or more and a wall thickness of about 10 mm or more. When determining the values of RCP pipe according to the present invention, the outer diameter and the wall thickness was chosen to 110 mm and 10 mm, respectively. While the outer side of the pipe is at ambient pressure (atmospheric pressure), in the inner part of the tube pump pressure and maintain it constant in the inner part of the pipe at 0.5 MPa positive pressure. Pipe and surrounding equipment thermostatic to a predetermined temperature. In order to avoid decompression during the test inside the pipe mounted shaft with a certain number of disks. To initiate bystrorasshiryayuscheysya longitudinal cracks on the pipe, towards the end, in the so-called zone and is iluzii, shoot knife projectile with well-defined forms. Avoid unnecessary deformation of the pipe zone initiation equip the supporting wall. Equipment set up in such a way that the test material has passed the initiation of the crack, and at different temperatures are conducting a series of tests. After each test measured the length of longitudinal cracks in the control zone, with a total length of 4.5 diameter, and put it on a graph against the established test temperature. If the crack length exceeded 4 diameter, crack believed spreading. If the pipe has passed the test at a given temperature, it has been successively lowered until a temperature (Tcrit.), in which the pipe is not passed the test.

The test pressure for pipes without incision

Pressure test the pipes 32 mm without incision was performed according to ISO 1167. The time of destruction expressed in hours.

Pressure test the pipe with cuts

The test pressure is 110 mm pipes with incisions was performed according to ISO 13479.

Test impact strength Charpy

The strength of the blow was determined by testing the impact strength according to Charpy ISO 179-1 (manually) or ISO 179-2 (devices)

Bending modulus

Bending modulus was determined according to ISO 178 at the constant speed of 2 mm/min

The modulus of elasticity

The modulus of elasticity determined and according to ISO 527-2 (test sample 1) at the constant speed of 1 mm/min

Rheological parameters

Rheological parameters such as the index of thinning under shear stress (SHI) and the viscosity was determined using a rheometer, preferably Physica MCR 300 Rheometer from Anton Paar. The definition and measurement conditions are presented in detail in WO 00/22040 on page 8, line 29 to page 11, line 25.

Examples

Example 1

In a loop reactor with a capacity of 50 DM3added with a speed of 32 kg/h propane at a rate of 8.3 g/h of hydrogen and ethylene. The operating temperature was 60°C and working pressure - bar 61.

The suspension was removed from the reactor and transferred to the loop reactor with a capacity of 500 DM3. The reactor was operating at 85°C and a pressure of 58 bar. The catalyst with a single center of polymerization on the metal, obtained as described in EP 1462464, routinely submitted to the loop reactor with a speed of 29 g/min Additional ethylene, 1-butene, diluent propane and hydrogen was continuously introduced into the reactor so that the rate of polymer formation was 35 kg/h, p2the polymer was 110 g/10 min, and the density of the polymer was 939 kg/m3.

The suspension is continuously removed from the reactor and transferred to the stage of rapid evaporation, where the hydrocarbons were removed from the polymer. Then the polymer was transferred into a gas phase reactor, where the polymerization was continued. The reactor temperature was 80°C and the pressure is s 20 bar In the reactor was filed ethylene, hydrogen and 1-hexene, therefore, to provide conditions under which the rate of polymer formation was 34 kg/h Performance of the catalyst was 2.4 kg/g catalyst.

The ratio of the amounts of the polymer obtained in suspension (reactor 2) and gas-phase (reactor 3) the reactor was 51:49.

Then the polymer was mixed with 1500 million-1calcium stearate and 3000 million-1Irganox B. The target compound had a density of 937 kg/m3and MWD 9,1.

Then compounded material through the extrusion was turned into a tube with an outer diameter of about 110 mm and a thickness of about 10 mm and an external diameter of 32 mm and thickness 3 mm, respectively.

Data on the conditions of polymerization, the resin/composition and pipe made from them, are summarized in Table 1.

Comparative example 1

The resin for pipes received a three-stage method in a loop reactor for terpolymerization, followed by first loop reactor, and then the gas-phase reactor as described in Example 1. The ratio was 2:42:56. In two consecutive loop reactors comonomer not used, while in the high molecular weight fraction obtained in gas-phase reactor, as co monomer used 1-butene in an amount such that the content of co monomer of 1-butene in the final polymer was 2.9 wt.%. Used catalyst of the Ziegler-N the TTA, as described in EP 688794. The value of Mnfor the final polymer was found to have $ 8600 g/mol and the value of Mwamounted to 240,000 g/mol. Thus, the relation of Mw/Mn28. Additional data presented in the Table below.

The material is then mixed with stabilizers and technical carbon and by extrusion were transferred to tubes with an external diameter of about 110 mm at a thickness of about 10 mm and a diameter of 32 mm at a thickness of 3 mm, respectively.

Table
UnitsExample 1Comparative example 1
The REACTOR TERPOLYMERIZATION
Temperature°C6050
Pressurebar6164,2
Ratiowt.%02
LOOP REACTOR
Temperature °C8595
Pressurebar5864
The concentration of C2mol.%the 5.73,5
The relation of H2/S2mol/KMOL0,46950
Relationship With4/S2mol/KMOL920

Ratiowt.%5144
CTP2g/(10 min)110325
Densitykg/m3939972
Comonomerbutene-1
GAS-phase REACTOR
Temperature°C8085
Pressurebar2019,5
The relation of H2/C2mol/KMOL050
The ratio of C4/C2mol/KMOL-200
The ratio of C6-C2mol/KMOL4-
Ratiowt.%4954
ComonomerHEXEN-1Butene-1
Density is the main resinkg/m3936940
MIXINGThe EXTRUDERJSW CIM90PJSW CIM460P
Supply kg/h217
Energy intensitykW*h/t277235
Melting point°C222285
The properties of the COMPOUNDED RESIN/RECEIVED PIPES
The content of hexene-1wt.%1,30
The content of butene-1wt.%1,62,9
CTP2g/(10 min)0,45
CTP5g/(10 min)1,40,85
CTP21g/(10 min)19
Mwg/mol157000240000
Mn g/mol172008600
MWD9,128
Density-mixturekg/m3937,2951
SHI(of 2.7/210)8,629,4
SHI(5/300)15,252,5

Eta0,05PA*s2345052400
The modulus of elasticityMPa640
Bending modulusMPa596845
Impact resistance at 0°CkJ/m21016
Impact resistance at -20°CkJ/m2 5,9
Pressure test the pipes 32 mm without incision
10.0 MPa at 20°Chmore 4719
12,0 MPa at 20°Ch4144
4,6 MPa at 80°Ch6321
5.1 MPa at 80°Ch2
5,4 MPa at 80°Ch6259
Pressure test the pipes 110 mm incisions
4.0 MPa at 80°ChMore than 5000
of 4.45 MPa at 80°Ch2731
Resistance to rapid crack propagation, Tcrit.°C-4

1. Polyethylene composition for the production of pipes, comprising a plastic main resin that contains
A. a copolymer of ethylene as a fraction (a) and
B. Homo - or copolymer of ethylene as a fraction (B), where the fraction (A) has a lower molecular weight than fraction (B),
moreover, the PE the main resin obtained by the polymerization method, in which the polymerisation of at least one of the fractions (a) and (b) apply the catalyst with a single center of polymerization on the metal (SSC), and the main resin has
(i) a density less than 940 kg/m3,
(ii) CTP2(the flow rate of the melt) at 190°C /2,16 kg) from 0.01 to 10 g/10 min, and the composition has
(iii) bending modulus of 400 to 820 MPa.

2. The polyethylene composition according to claim 1, where the polyethylene composition has an impact strength Charpy at 0°C for at least 10 kJ/m2according to the results of measurement according to ISO 179 (international organization for standardization).

3. The polyethylene composition according to claim 1 or 2, where the polyethylene composition demonstrates in the test RCP-S4 (determination of resistance to rapid crack propagation) the critical temperature of 2°C or below for measurements according to ISO 13477.

4. The polyethylene composition according to any one of claims 1 to 3, where the polyethylene composition has a value of slow RA the proliferation of cracks at least 165 hours on the test pipe with a notch according to ISO 13479 at 80°C and a load of 5.4 MPa.

5. The polyethylene composition according to any one of claims 1 to 4, wherein the polyethylene composition has a nominal value of the minimum long-term strength (MRS) at least 6,3 according to the results of measurement according to ISO/TR 9080.

6. The polyethylene composition according to claim,1 wherein the molecular weight distribution of the polyethylene resin base is from 5 to 25.

7. The polyethylene composition according to claim 1, where component (A) is a copolymer of ethylene and C4-C20alpha-olefin comonomers.

8. The polyethylene composition according to claim 1, where the fraction (A) has a density of from 920 up to 962 kg/m3.

9. The polyethylene composition according to claim 1, where component (A) is the flow rate of the melt (190°C/2,16 kg) P2from 10 to 300 g/10 minutes

10. The polyethylene composition according to claim 1, where in the polyethylene resin, the mass ratio of fractions (a) and fraction (b) is from 60:40 to 40:60.

11. A method of obtaining a polyethylene composition comprising a polyethylene core resin, which includes
A. a copolymer of ethylene as a fraction (a) and
B. Homo - or copolymer of ethylene as a fraction (In),
moreover, the fraction (A) has a lower molecular weight than fraction (B), where in the polymerization of at least one of the fractions (a) and (b) apply the catalyst with a single center of polymerization on the metal (SSC), where the main resin has
(i) the density is who 940 kg/m 3and
(ii) P2at 190°C/2,16 kg from 0.001 to 10 g/10 min,
and the composition has
(iii) bending modulus of 400 to 820 MPa.

12. Pipe made from polyethylene composition according to claim 1.

13. The use of a polyethylene composition according to claim 1 for the production of pipes.



 

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8 cl, 3 dwg

FIELD: machine building.

SUBSTANCE: here is disclosed fabrication of pipe out of composite materials consisting in forming adhesion layer on mandrel, in successive forming sealing, stretching, power and under winding layers by winding composite materials impregnated with polymer binding and in following laying polymer binding on it. The sealing layer is formed by either winding two layers of a band out of non-woven material with pitch of 0.5 of band width impregnated with polymer binding and successive laying one layer of glass cloth on it or by winding two layers of the band out of glass cloth impregnated with glue at pitch of 0.5 of band width. The power layer is formed by the method of cross-layered lengthwise-cross winding out of strands of glass twisted complex thread soaked with polymer binding. The stretching layer is made by spiral-screw winding strands of glass twisted complex thread without impregnation with polymer binding. The under winding layer is formed by spiral screw or cross-layered lengthwise-cross winding strands out of glass twisted complex thread soaked with polymer binding.

EFFECT: increased weight perfection of transport-starting container out of pipe fabricated by winding composite materials; facilitation of pressure tightness and rigidity of pipe.

FIELD: chemistry.

SUBSTANCE: invention relates to use of an antioxidant to increase resistance of a polyolefin composition meant for making pipes to decomposition caused by contact with water, which contains CIO2. The antioxidant is selected from a) a group of phenols of formula I, where R is an unsubstituted or substituted aliphatic or aromatic hydrocarbon radical which can contain heteroatoms, or R is a heteroatom, R' and R" independently denote an unsubstituted or substituted hydrocarbon radical which can contain heteroatoms, or H, X1, X2 and X3 independently denote an unsubstituted or substituted hydrocarbon radical which can contain heteroatoms, or H or OH, where at least X1, X2 or X3 is OH, n assumes values from 1 to 4, and at least one of the phenol substitutes R, R' and/or R" contains at least one sulphur, phosphorus and/or nitrogen heteroatom or from b) amine compounds of formula II, where R1, R2, R3, R4, R5 and R6 independently denote a hydrogen atom or an aliphatic or aromatic hydrocarbon radical, possibly containing heteroatoms, or selected from c) sulphur-containing compounds of formula Ra-S-Rb III, where Ra and Rb independently denote an aliphatic or aromatic hydrocarbon radical, possibly containing heteroatoms.

EFFECT: antioxidant used has low susceptibility to extraction with water carried by a pipe made from such a polyolefin composition.

7 cl, 1 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a polyethylene composition for making pipes, which contains a polymer base comprising two polyethylene fractions with different molecular weight, to a pipe containing said composition and to use of said composition to make articles, preferably pipes. The polymer base accounts for not less than 90 wt % of the overall composition and has density of 932-938 kg/m3.The fraction of ethylene homo- or copolymer (A) has lower average molecular weight than the fraction of ethylene homo- or copolymer. The polyethylene composition has melt flow rate MFR5 between 0.1 and 0.6 g/10 min and shearing stress η2.7 kPa between 85 and 230 kPa. The polyethylene composition has improved combination of properties, particularly high flexibility, high mechanical strength and good long-term stability.

EFFECT: pipes obtained from the disclosed polyethylene composition have good operational characteristics, long-term stability and good resistance to rapid propagation of cracks, which facilitates their use in conveying liquids under pressure.

16 cl, 1 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a polyolefin composition which is suitable for making pipes. The composition used to make pipes contains polyolefin (A), a compound (B) which is bis(2,4-dicumyphenyl)pentaerythritol diphosphate, and a phenol compound (C) of formula (I), where R denotes an unsubstituted or substituted aliphatic or aromatic hydrocarbon radical, which can contain heteroatoms, or R denotes a heteroatom; each X1-X5 denotes H, OH and/or R'; where R' denotes a hydrocarbon radical or a hydrogen atom, and n equals 1-4; and g) possibly a stabiliser against UV light (D).

EFFECT: composition has low tendency to migration of additives and their decay products, particularly phenol compounds and a light stabiliser, not more than 1,8 mcg/l with surface to volume ratio S/V between 11,70 and 12,30 dm-1, without loss of stability.

10 cl, 3 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: polymer base is not less than 90 wt % of the overall composition and has density of 940-947 kg/m3.The fraction of homo- or copolymer of ethylene (A) has lower average molecular weight than the fraction of homo- or copolymer of ethylene. The polyethylene composition has melt flow rate MFR5 of 0.1-0.5 g/10 min and viscosity reduction index during shear (2.7/210) of 10-49, has better combination of properties, in particular high flexibility and high mechanical strength and good long-term stability.

EFFECT: pipes made from the disclosed polyethylene composition have good performance properties, especially in terms of flexibility and rapid propagation of cracks while preserving minimal required strength, processing characteristics, impact viscosity and resistance to slow propagation of cracks.

14 cl, 1 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: addition of a stabilising amount of a mixture to high density polyethylene, where the said mixture contains 4,4'-bis(α,α-dimethylbenzyl)diphenylamine and sterically hindered phenol, enables to increase resistance to decomposition caused by chlorinated water.

EFFECT: pipes made from such a stabilising composition are suitable for conveying hot water, particularly chlorinated water.

6 cl, 3 ex

FIELD: machine building.

SUBSTANCE: cooling agent pipeline includes the following layers: outer layer from moulding compound on the basis of polyamide; inner layer having the thickness at least of 0.3 mm and containing polypropene, 0.02 wt % of heat stabiliser. Polypropene is hetero-phase copolymer on the basis of propene, which contains 0.5 wt % to 20 wt % of ethene.

EFFECT: increasing heat stability and mechanical pipeline strength.

10 cl, 1 tbl

FIELD: machine building.

SUBSTANCE: multi-layer pipe is made out of composite material corresponding to reinforced materials in form of alternate mono-layers with cross and lengthwise laying of reinforced material impregnated, for example with thermo-reactive binding. Binding consists of internal and external structure layers divided with a barrier layer. The barrier layer is made out of a layer of heat insulating foam applied on external surface of the internal structure layer and of an additional layer arranged between the layer of heat insulating foam and internal surface of the external structure layer. The latter corresponds to successively lain metal screens out of continuous bands divided with polymer material.

EFFECT: increased heat resistance of wall of multi-layer pipe.

5 cl, 1 dwg

FIELD: metallurgy.

SUBSTANCE: composition consists of copolymer of propylene, of first copolymer of ethylene with at least one linear or branched alpha-olefine having 3-8 carbon atoms and of second copolymer of ethylene with at least one linear or branched alpha-olefine having 3-8 carbon atms. Copolymer of propylene has value of poly-dispersity index within ranges from 4.5 to 10 and contents of isotactic penthalogy above 97.5 mol %. Also, said copolymer contains at least 95 wt % (relative to copolymer) links derivative from propylene. The first copolymer - copolymer of ethylene contains from 25 to less, than 40 wt % relative to this copolymer) links derivative from ethylene and is soluble in xylol at 25°C within the ranges from over 85 to 95 wt %, while the second copolymer of ethylene contains from 50 to less 75 wt %relative to this copolymer) links derivative from ethylene and is soluble in xylol at 25°C within the ranges from over 50 to 85 wt %, and possesses characteristic viscosity of fraction soluble in xylol below 1.8 sh/g.

EFFECT: composition possesses good resistance to stress causing whitening, and lustre combined with good balance of mechanical properties.

8 cl, 3 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a biodegradable thermoplastic composition used in making films and various hot-moulded articles in form of consumer packaging. The composition contains polyethylene, a copolymer of ethylene and vinylacetate, starch, nonionic surfactant and schungite.

EFFECT: composition has good rheological characteristics and is biodegradable under the effect of light, moisture and soil microflora.

2 tbl, 4 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a polyethylene moulding composition for pressure casting finished parts, for example bottle tops and bottles, and to a method of preparing said moulding composition. The composition has polymodal molecular weight distribution and contains an ethylene homopolymer (A) with low molecular weight, an ethylene copolymer (B) with high molecular weight an ethylene copolymer (C) with ultrahigh molecular weight. At temperature 23°C, the moulding composition has density of 0.948-0.957 g/cm3, melt flow rate MFR (190°C/2.16 kg) of 1-2.7 dg/min and coefficient of viscosity VN3 of the mixture of ethylene homopolymer A, copolymer B and ethylene copolymer C, measured in accordance with ISO/R 1191 in decalin at temperature 135°C ranging from 150 to 240 cm3/g.

EFFECT: besides processability, the moulding composition has high mechanical strength and rigidity, excellent organoleptic properties and high cracking resistance under the effect of the surrounding medium.

12 cl, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to dispersion powdered compositions re-dispersed in water, a method of preparing said compositions, as well as to their use in construction materials. The composition is prepared based on polymers of one or more ethylene unsaturated monomers. The composition additionally contains one or more dimeric surfactants in form of alkyne derivatives, an one or more protective colloids. Powdered compositions are obtained through emulsion or suspension polymerisation of one or more ethylene unsaturated monomers. The reaction takes place in an aqueous medium followed by drying the obtained aqueous dispersions, while adding one or more dimeric surfactants.

EFFECT: use of obtained powdered compositions in self-levelling filler or fluid solutions for making seamless floors, prevents formation of irregularities, depressions and small pores on the surface, as well as formation of air pockets in the deposited layer.

18 cl, 2 tbl, 12 ex

FIELD: chemistry.

SUBSTANCE: mixture contains two different polyolefin and ethylene/α-olefin copolymers. The ethylene/α-olefin copolymer is a block-copolymer containing at least one hard block and at least one soft block. The ethylene/α-olefin copolymer can function as a component which improves compatibility between two polyolefins which may be incompatible. The disclosed polymeric mixtures can be used in making various articles such as tyres, hoses, belts, linings, shoe soles, cast and moulded articles. Said mixtures are especially useful for applications requiring melt strength, such as big articles made by blow moulding, foam and bundled bars.

EFFECT: improved compatibility of mixtures.

27 cl, 10 dwg, 13 tbl, 40 ex

FIELD: chemistry.

SUBSTANCE: composition with multimodal distribution of molecular weight has density between 0.94 and 0.95 g/cm3 at 23°C and melt flow index (MFI190/5) between 1.2-2.1 dg/min in accordance with ISO 1133. The composition contains 45-55 wt % low molecular weight homopolymer A of ethylene, 30-40 wt % high molecular weight copolymer B of ethylene and another olefin containing 4-8 carbon atoms, and 10-20 wt % ultrahigh molecular weight copolymer C of ethylene and another olefin containing 4-8 carbon atoms. The composition has high processibillity and resistance to mechanical loads and breaking, especially at temperatures below 0°C.

EFFECT: flawless coating for steel pips has mechanical strength properties combined with high hardness.

10 cl, 1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to polymer moulding compositions meant for moulding screw fitments. The composition contains a copolymer of ethylene and 1-hexene with density between 0.947 and 0.962 g/cm3 and melt index between 2 and 8 g/10 min and another copolymer of ethylene and 1-hexene with density between 0.912 and 0.932 g/cm3 and melt index between 0.25 and 6 g/10 min. Difference in density of the two polyethylenes is equal to or greater than 0.03 g/cm3. Selection of the components enables to obtain polymer compositions which have sufficient resistance to cracking and impact strength at low production expenses and without loss of other necessary operational properties.

EFFECT: screw fittings made from the said composition have strength which conforms to requirements for maintaining pressure, particularly in bottles with carbonated drinks, as well as plasticity for providing an airtight seal without need for lining and without change in taste or smell of the contents of the bottle.

9 cl, 4 ex, 6 tbl

FIELD: chemistry.

SUBSTANCE: invention relates to polyethylene and articles made by injection moulding polyethylene. Polyethylene contains homopolymers of ethylene and/or copolymers with ethylene with molecular weight distribution Mw/Mn between 3 and 30, density of 0.945 - 0.965 g/cm3, average molecular weight Mw between 50000 g/mol and 200000 g/mol, high-load melt index (HLMI) between 10 and 300 g/10 min. The polymer contains 0.1-15 branches/1000 carbon atoms, where 1-15 wt % polyethylene with the highest molecular weight has degree of branching greater than 1 branch of side chains with length greater than CH3/1000 carbon atoms.The polyethylene is obtained using a catalyst composition which contains at least two different polymerisation catalysts, where A) is at least one hafnocene-based polymerisation catalyst (A2), and B) is at least one polymerisation catalyst based on an iron component, having a tridentate ligand which contains at least two ortho-, ortho-disubstituted aryl radicals (B). The disclosed polyethylene can be subjected to processing treatment on standard injection moulding apparatus.

EFFECT: articles obtained through injection moulding is uniform and can further be improved by increasing rate of injection moulding or high melting point.

9 cl, 2 tbl, 2 ex

FIELD: chemistry.

SUBSTANCE: invention relates to polyolefin compositions which have high decolouration and impact resistance. The composition contains from 50 to less than 70 wt % crystalline propylene homopolymer, 13-28 wt % elastomeric ethylene and propylene copolymer and 10-22 wt % polyethylene. Total amount of the elastomeric copolymer and polyethylene in the composition is more than 30 wt %. The crystalline propylene homopolymer has polydispersity index ranging from 4 to 10 and amount of isotactic pentades (mmmm) measured using 13C-NMR method on a fraction which is insoluble in xylene at 25°C more than 97.5 mol %. The elastomeric ethylene copolymer is partially soluble in xylene at ambient temperature. The polymer fraction which is soluble in xylene has value of inherent viscosity, measured in tetrahydronaphthalene at 135°C, which ranges from 2 to 4 dl/g. Polyethylene has inherent viscosity ranging from 1 to 3 dl/g.

EFFECT: obtained polypropylene compositions have relatively low hardness, high impact resistance and high resistance to decolouration, which enables their use in the motor car industry, particularly in bumpers and interior finishing, packaging and household objects.

5 cl, 4 tbl, 6 ex

FIELD: chemistry.

SUBSTANCE: composition contains at least one high-molecular polyethylene and at least one low-molecular polyethylene component. The high-molecular polyethylene component of the composition has molecular weight distribution of approximately 6 to 9, content of short-chain branches less than approximately 2 branches per 1000 carbon atoms of the main chain and Mz - approximately 1100000 or greater. The ratio of weight-average molecular weight of the high-molecular polyethylene component to the weight-average molecular weight of the low-molecular polyethylene component is less than 20. The disclosed composition has density greater than 0.94 g/cm3, resistance to cracking under the influence of the surrounding medium greater than 600 hours and percentage swelling greater than 70%.

EFFECT: improved mechanical strength characteristics, suitable for blow moulding.

22 cl, 1 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: lubricated polymer composition from which an article is made contains one or more polymers which are low-density polyethylene in amount ranging from approximately 95% to approximately 99.5% of the total weight of the composition, and one or more lubricating substances. The one or more lubricating substances are selected from a group comprising erucamide, sterile erucamide, bis-erucamide and any of combination thereof.

EFFECT: obtained articles have high softness, flexibility and oiliness.

33 cl, 7 tbl, 25 ex

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