Multimodal polymer

FIELD: chemistry.

SUBSTANCE: invention relates to cross-linked multimodal polyethylene. Described is cross-linked polyethylene, which includes multimodal ethylene polymer with density less than 950 kg/m3, obtained by polymerisation in presence of catalyst with one active centre. Polymer has MFR21 from 10 to 20 g/10 min. Index of viscosity reduction in shifting of TVR2.7/210 is at least 4. Also described is application of multimodal ethylene polymer in production of cross-linked pipe and method of multimodal ethylene polymer obtaining.

EFFECT: obtaining good workability and essential cross-linking in one and the same polymer.

15 cl, 3 tbl, 2 ex

 

This invention relates to a method for production of stitched multimodal polyethylene, as well as the stitching of the multimodal polyethylene per se. The invention also relates to crosslinked polyethylene and products, preferably pipes made of cross-linked polyethylene.

It is known the use of polymers for pipes for various purposes, such as transporting fluid, for example, the transport of liquids or gases, such as water or natural gas. In General, these pipes fluid is under pressure. These tubes can be made from polyethylene, such as medium-density polyethylene (PASP) or high density polyethylene (HDPE), usually a density of about 950 kg/m3.

In the related descriptions of the invention of EP-A-1927626 and EP-A-1927627 describe a pipe formed from a component which is a copolymer with a lower molecular weight, and the component, which homopolymers with higher molecular weight, having a density of less than 940 kg/m3.

Pipes can be produced by different technologies, such as plunger extrusion or screw extrusion. Screw extrusion is one of the major steps in the processing of polymers, as well as a key component in many other technological operations. An important goal in the way screw extras and is the creation of such pressure in the polymer melt, so it can be ekstradiroval through the head.

Crosslinking improves parameters such as resistance to heat deformation, and therefore tubes for applications using hot water, such as pipes for floor heating or for hot water distribution, usually made of crosslinked polyethylene (PE-X). However, the pipe of the previous prior art, such as pipes made unimodal high density polyethylene (HDPE), have several drawbacks. In order to meet the high requirements of the so-called rules HDPE-X for hot and cold water applications (for example, EN ISO 15875), you must apply the polyethylene of relatively high density. This makes the resulting tube is relatively rigid. This rigidity is even more pronounced when using insulating layers on top of or inside the core tube.

In order to improve the ability to crosslinking and, therefore, reduce the amount of cross-linking agent, for example, peroxide cross-linking of polyethylene pipes, generally you want to use the ethylene polymer with a relatively low rate of flow of the melt (P), i.e. high molecular weight. However, this leads to poor workability, that is, reduced performance technical line during extrusion.

Therefore it is generally true is but to achieve good workability and significant stevenote in the same polymer. The inventors tried to find a solution to these problems is a good stevenote in combination with good machinability, in particular in the manner of a screw extrusion process.

The aim of the present invention is to provide polymeric compositions with improved ability to crosslinking, for example with a degree of crosslinking of at least 60%, and flexibility, and with good machinability, making possible the production of pipes, especially when using a screw extrusion process. According to the experience of the inventors, it is difficult to obtain a polymer, which has excellent workability, and also provides sufficient stevenote. To maintain good workability in the way of a screw extrusion, the necessary balance between Mw and Mw/Mn. In the case of polyethylene obtained in the presence of a catalyst and an active centre (OAC PE), which requires bi - or multimodal polymers. Further, in order to avoid yellowing, gels and inhomogeneities, you want to apply the polymers with such a low ash content as possible, that is, the polymer to be obtained in the presence of a catalyst with high activity.

The inventors have discovered that the specific polymer possesses all these qualities.

Thus, from the point of view of the first embodiment, the invention provides a multimodal ethylene polymer is letestu below 950 kg/m 3obtained by polymerization in the presence of a catalyst and an active centre, and with

CTP21from 10 to 20 g/10 min,

the rate of decrease in viscosity when the shear PSV2,7/210at least 4, and preferably

stevenote at least 60%.

From the point of view of the second embodiment, the invention provides a polymer composition comprising the above-defined multimodal ethylene polymer, and at least one additive and/or other olefinic component.

From the point of view of another embodiment, the invention provides a method of obtaining a multimodal ethylene polymer, including:

(1) polymerization of ethylene in the presence of a catalyst and an active centre of ethylene and, optionally, at least one of the co monomer in the first stage;

(2) polymerization of ethylene in the presence of the same catalyst and an active centre of ethylene and, optionally, at least one of the co monomer in the second stage;

so in order to form the above-described ethylene polymer, for example, the multimodal ethylene polymer with a density of less than 950 kg/m3obtained by polymerization in the presence of a catalyst and an active centre, and with

CTP21from 10 to 20 g/10 min,

the rate of decrease in viscosity when the shear PSV2,7/210at least 4, and predpochtite the flax

stevenote at least 60%.

From the point of view of another embodiment, the invention provides cross-linked polyethylene, comprising the above-described multimodal ethylene polymer which is crosslinked.

From the point of view of another embodiment, the invention provides use of the above multimodal ethylene polymer in the production of pipes, especially custom made pipes.

From the point of view of another embodiment, the invention provides a method of producing pipe from cross-linked ethylene polymer, including the formation of the above-described ethylene polymer pipe by extrusion, especially screw extrusion, and its stitching.

Multimodal ethylene polymer

Under ethylene polymer is meant a polymer in which ethylene is the basic repeating element, for example, 70 wt.% ethylene, preferably at least 85 wt.% of ethylene.

The ethylene polymer of the present invention has a density of less than 950 kg/m3preferably less 949 kg/m3preferably not more than 947 kg/m3. Ideally the polymer has a density of at least 920 kg/m3for example, at least 925 kg/m3. The preferred density range is from 932 to less than 950 kg/m3mainly from 940 to less than 950 kg/m3. This density can be obtained is ay polymerization of the ethylene polymer in the presence of a catalyst and an active centre and it has several advantages. The density of the polymer below the normal mean, what made him pipe is more flexible. This is important, among other things, to the type of pipe, for example, for floor heating. Next, lower the density of the primary ethylene polymer means a lower crystallinity, which, in turn, means that less energy is required to melt the polymer. This leads to increased productivity in the manufacture of pipes.

More importantly, lower density/crystallinity of the ethylene polymer of the present invention, obtained in the presence of a catalyst and an active centre, unexpectedly gives the same or superior characteristics when tested under pressure compared with previous technology with higher density/crystallinity, it is possible to obtain one characteristic pressure test with a more flexible pipe according to the present invention and the conventional material with higher density and crystallinity.

The ethylene polymer according to the invention preferably has a P21from 10 to 20 g/10 min, more preferably from 11 to 19 g/10 min, mainly from 12 to 18 g/10 min, for example, from 13 to 17 g/10 minutes

P is a measure of the fluidity and, therefore, the workability of the polymer. The higher the speed, the fluidity of the melt,the lower the viscosity of the polymer. PAGE also important to provide sufficient stevenote. A very narrow range of P21ensures that stevenote declared polymer is excellent. If P21is less than 10 g/10 min, extraterrest is poor, resulting in products with poor surface quality. If P21more than 20 g/10 min, did not achieve the desired degree of crosslinking.

Values of P5can be from 0.1 to 5 g/10 min. Ideal value of P5is from 0.5 to 3 g/10 minutes

The ethylene polymers according to the invention preferably have a molecular weight Mw of at least 100,000, preferably at least 120000, mainly at least 150000.

The values of Mn should preferably be at least 25000, more preferably at least 30,000.

Preferably the ethylene polymer of the present invention, obtained in the presence of a catalyst and an active centre has a wide molecular weight distribution, as determined by its rate of decrease of viscosity shear (PSV). PSV is the ratio of the complex viscosity (η*) at two different shear stresses and is a measure of the width (or narrowness) of molecular mass distribution.

According to the present invention the ethylene polymer has the rate of decrease in viscosity when the shear PSV , i.e. the ratio of complex viscosity at 190°C. and a shear stress of 5 kPa(η5KPand*)and the complex viscosity at 190°C. and a shear stress of 300 kPa(η300KPand*)at least 5, preferably at least 6.

According to the present invention the ethylene polymer has the rate of decrease in viscosity when the shear PSV2,7/210, i.e. the ratio of complex viscosity at 190°C. and a shear stress of 2.7 kPa(η2,7KPand*)and the complex viscosity at 190°C. and a shear stress of 210 kPa(η210KPand*)at least 4. Preferably PSV2,7/210is at least 10.

Another way of measuring the molecular mass distribution (MMD) is a civil act (helpanimals chromatography). Molecular weight distribution (led is in MMD, that is, Mw/Mn) of the present invention is more than 4. Preferably the mold is less than 10, for example, less than 8. This molecular weight distribution increases stevenot, for example, requires less peroxide or radiation to obtain a certain degree of crosslinking.

According to a preferred embodiment of the invention the ethylene polymer has a complex viscosity at a shear stress of 5 kPa/190°C,η5KPand*equal to at least 10000 PA·s, more preferably at least 15000 PA·S.

According to another preferred embodiment of the invention the ethylene polymer has a complex viscosity at a shear stress of 0.05 rad/s at 190°C,η0,05pandd/with a*equal to at least 10000 PA·s, more preferably at least 15000 PA·S.

An additional advantage of the method according to the invention and, therefore, the polymers according to the invention, is a low ash content and excellent distribution of particle sizes. Samples with high ash content are more susceptible to oxidation, and when the two reactors educated polymers them who have less ash and more uniform distribution of ash in the absence of particles with very high ash content.

The ash content of the ethylene polymer according to the invention may be less than 500 parts per million, preferably less than 400 parts per million, mainly less than 350 parts per million Take into account the fact that ash is affected by the polymerization conditions, especially the partial pressure of ethylene, used during the polymerization. Lower the partial pressure of ethylene leads to a higher ash content.

Also observe that the method according to the invention provides better distribution of ash content (that is, any present ash is distributed in a wider range of particles and not concentrated in some fraction of the polymer). It is noted that high levels of ash are particularly prevalent in the smaller particles when the polymer is unimodal and received during one stage of polymerization.

Low ash content is also associated with low yellowness for made of polymer products. Thus, products made from ethylene polymer according to the invention (preferably crosslinked ethylene polymer according to the invention can have a yellowness indices less than 2, preferably less than 1.5.

Multimodal ethylene polymer according to the invention receives at least two stages, ideally only two stages, and therefore it contains at least two fractions, preferably only two factions.

T is pmin "multimodal" means here unless otherwise specified, the multimodal with respect to molecular weight distribution, and therefore includes a bimodal polymer. Usually, a polyethylene composition comprising at least two polyethylene fractions, which were obtained under various conditions of polymerization, leading to different (mass-average) molecular weights and molecular weight distributions for the fractions, is referred to as "multimodal". The prefix "multi" refers to the number of different polymer fractions present in the polymer. Thus, for example, the multimodal polymer includes so-called "bimodal" polymer consisting of two fractions. The shape of the curve of the molecular-mass distribution, i.e. the graph of the proportion of the weight of the polymer as a function of its molecular weight, for multimodal polymer has two or more peaks, or usually explicitly broadened in comparison with the curves for the individual fractions. For example, if the polymer is produced in a sequential multi-stage method, using reactors connected in series and using different conditions in each reactor, the polymer fractions obtained in different reactors, each have their own molecular weight distribution and mass-average molecular weight. When registering curve of the molecular-mass distribution is s such a polymer, individual curves of these fractions usually together form the extended curve of the molecular-mass distribution for the whole of the resulting polymer product.

Multimodal polymer applicable to the present invention includes a component with a lower mass-average molecular mass (hmm) and a component with a higher mass-average molecular mass (AMM). The specified component MMO has a lower molecular weight compared with the component of the AMM. This difference is preferably at least 5000 units.

In one preferred embodiment of the specified multimodal polymer includes at least (1) a component with a lower mass-average molecular mass (hmm), which homopolymer or copolymer of ethylene, and (2) a component with a higher mass-average molecular mass (AMM), which homopolymer or copolymer of ethylene. Preferably at least one of these MMOs and AMM component is a copolymer of ethylene with at least one co monomer. It is preferable that at least the specified AMM component was a copolymer of ethylene. Alternatively, if one of these components is homopolymers, then the specified MMO preferably is homopolymer.

Alternatively, the specified multimodal etileno the second polymer may include additional polymeric components, for example, three components, which is a tri-modal ethylene polymer. If necessary, the multimodal ethylene polymers according to the invention can also include, for example, up to 10 wt.% well-known polyethylene prepolymer, which is obtained at the stage of preliminary polymerization, as is well known in the prior art, for example as described in WO 9618662. In the case of such a prepolymer, forprimary component included in one of the MMO and AMM components, preferably in the MMO component, as defined above.

Preferably specified multimodal polymer is bimodal, including these MMOs and AMM components and, if necessary, pre-polymerized fraction, as defined above.

Specified MMO component of the multimodal polymer preferably has a CTP2at least 5 g/10 min, preferably less than 50 g/10 min, for example, up to 40 g/10 min, such as from 5 to 20 g/10 minutes

The density of the MMO component specified multimodal polymer can range from 930 to 980 kg/m3for example from 930 to 970 kg/m3more preferably from 935 to 960 kg/m3.

MMO component specified multimodal polymer can range from 30 to 70 wt.%, for example from 40 to 60 wt.% multimodal polymer with AMM component comprising from 70 to 30 wt.%, for example from 40 to 60 wt.%. the one embodiment of the specified MMO component comprises 50 wt.% or more multimodal polymer, as defined above or below.

AMM specified component of the multimodal ethylene polymer has a lower P2than MMO component.

The ethylene polymer according to the invention can be ethylene homopolymers or copolymer. Under ethylene homopolymers understand the polymer, which is formed essentially only ethylene Monomeric units consisting of ethylene 99.9 wt.% or more. Consider that minor traces of other monomers may be present due to the fact that the industrial ethylene contains trace amounts of other monomers.

The ethylene polymer according to the invention may also be a copolymer and, therefore, can be formed from ethylene with at least one other co monomer, for example, C3-20the olefin. The preferred comonomers are alpha-olefins, especially those containing from 3 to 8 carbon atoms. Other significant comonomers are dieny. The use of dienes as co monomer increases the unsaturation of the polymer and, thus, is way additional increase stevenote. The preferred danami are 64-20 diene, in which at least one double bond is in position 1 of the diene. Especially preferred danami are diene containing tertiary double bond. The term "critic the traveler double bond" here understand the double bond, which is substituted by three non-hydrogen groups (for example, the three alkyl groups).

Preferably comonomer selected from the group consisting of propene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1,7-octadiene and 7-methyl-1,6-octadiene.

The polymers according to the invention can include one monomer or two monomer, or more than two monomers. Preferred is the use of one of the co monomer. If you use two of the co monomer, preferably, if one is3-8the olefin, and the other is a diene as defined above.

The number of co monomer preferably is such that he is 0-3 mole.%, more preferably 0-1,5 mole.% and most preferably 0-1 mole.% the ethylene polymer.

However, preferably, if the ethylene polymer according to the invention includes a component of MMOs homopolymer component and TIM copolymer of ethylene, for example, a copolymer of ethylene and hexene.

The polymer according to the invention is obtained by polymerization in the presence of a catalyst and an active centre and it has a relatively low density and narrow molecular weight distribution. The use of the ethylene polymer obtained in the presence of a catalyst and an active center, gives the best description of the test pressure for a given density than the corresponding materials of the previous is its level of technology. Therefore, it is possible to apply the polymer lower density, which leads to a more flexible pipe. Moreover, for a polymer lower density also requires less energy to melt, which is an advantage in the production of pipes. Further, the use of a polymer with a low P obtained in the presence of a catalyst with one active site, allows you to use a lower amount of cross-linking agent to achieve the desired degree of crosslinking. The above-defined polyethylene in practice can be obtained using any conventional catalysts with one active site, including metallocene and not metallocene catalysts, as is well known in the prior art.

Preferably the specified catalyst is one of the catalysts, including metal, coordinated by one or more p-binding ligands. Such η-associated metals are usually transition metals of Groups 3 to 10, for example, Zr, Hf or Ti, especially Zr or Hf. η-binding ligand is typically acyclic ligand, i.e. Homo - cyclopentadienyls or heterocyclic group optionally condensed with or attached as a side group substituents. Such preferably metallocene, precatalysts with one active center was widely described in scientific and patent Lite is the atur for about twenty years. Here precatalysts refers to a specific complex of the transition metal.

The metallocene precatalysts can have the formula II:

(Cp)mRnMXq,(II)

in which:

each Ls is independently unsubstituted or substituted and/or condensed Homo - or heterosynaptically ligand, for example, substituted or unsubstituted cyclopentadienyls, substituted or unsubstituted indanilnykh or substituted or unsubstituted fluorenyl ligand;

one or more of the possible substituent(s)independently selected preferably from halogen, hydrocarbon (for example, C1-C20of alkyl, C2-C20alkenyl,2-C20the quinil,3-C12cycloalkyl,6-C20aryl or7-C20kilakila)3-C12cycloalkyl, which contains 1, 2, 3 or 4 heteroatom(s) in the ring portion, and6-C20heteroaryl,1-C20halogenoalkane,-SiR2", -OSiR3", -SR”,-PR2"or-NR2",

each R” independently is hydrogen or a hydrocarbon, for example, With1-C20the alkyl, C1-C20alkenyl,2-C20the quinil,2-C12cycloalkyl or6-C20by aryl, or, for example, in the case of-NR2"two Deputy R” can form a ring, for example, a ring of five or six components, together with the nitrogen atom to which they are attached;

R is a bridge of 1-7 atoms, e.g. a bridge of 1-4 carbon atoms and 0-4 heteroatoms, where the heteroatom(s) may be, for example, the atom(s) Si, Ge and/or O, where each atom of the bridge may be independently associated with substituents, such as1-C20alkalemia, three(C1-C20alkyl)Silovye, three(C1-C20alkyl)siloxy or6-C20akrilovye substituents, or a bridge of 1-3 atoms, for example, one or two heteroatoms, so the x as the atom(s) of silicon, Germany and/or oxygen, for example,-SiR21-where each R1independently is C1-C20alkilany,6-C20allowin or three(C1-C20alkyl)sillavan residue, such as trimethylsilyl;

M is a transition metal of Group 3 to 10, preferably 4 to 6, such as Group 4, for example, Ti, Zr or Hf, particularly Hf;

each X is independently a Sigma-ligand, such as H, halogen, C1-C20alkyl, C2-C20alkoxy, C2-C20alkenyl,2-C20quinil,3-C12cycloalkyl,6-C20aryl, C7-C20aryloxy,7-C20arylalkyl,7-C20arylalkyl, -SR”,-PR3",-SiR3",-OSiR3",-NR2"or-CH2-Y, where Y is a C6-C20what Rila, With6-C20heteroaryl,1-C20alkoxy, C6-C20aryloxy,NR2", -SR”,-PR3",-SiR3"or-OSiR3";

each of the aforementioned ring molecules by itself or as part of another molecule as Deputy for Cf, X, R” or R1may be optionally substituted, for example, With1-C20the alkyl which may contain Si atoms and/or;

n is 0, 1 or 2, for example 0 or 1,

m is 1, 2 or 3, for example, 1 or 2,

q is 1, 2 or 3, for example, 2 or 3,

where m+q is equal to the valence of M.

Accordingly, each X-CH2-Y each Y is independently selected from C6-C20aryl,NR2",-SiR3"or-O SiR3". Most preferably X-CH2-Y is benzyl. Every X, except-CH2-Y independently is halogen, C1-C20the alkyl, C1-C20alkoxy, C6-C20the aryl, C7-C20arylalkyl or-NR2"as defined above, for example, -N(C1-C20alkyl)2.

Preferably q is 2, each X is a halogen or-CH2-Y, and each Y independently is as defined above.

Cf is preferably cyclopentadienyl, indenolol, tetrahydroindene or fluorenyl, optionally substituted as defined above.

In a suitable subgroup of compounds of formula II, each Ls is independently carries 1, 2, 3, or 4 substituent as defined above, preferably 1, 2 or 3, such as 1 and 2 substituents which are preferably selected from C1-C20of alkyl, C6-C20aryl, C7-C20arylalkyl (where arelove ring by itself or as part of additional molecules may be optionally substituted as shown above),-OSiR3" where R” is as shown above, preferably1-C20the alkyl.

R, if present, is preferably methylene, ethylene or sillavan bridge, which allows you to replace silyl, as defined above, for example (dimethyl)Si=, (were)Si= or (trimethylsilylmethyl)Si=, n is 0 or 1, m is 2 and q is two. Preferably R” is not hydrogen.

A specific subgroup includes the well-known metallocene Zr, Hf and Ti with two η5-ligands, which can be cyclopentadienyls ligands, related or unrelated bridge bond, optionally substituted, for example, siloxy or alkyl (for example, C1-C6the alkyl, as defined above, or with two indanilnykh ligands, related or unrelated bridge bond, optionally substituted in any of the ring parts, for example, siloxy or alkyl, as defined above, for example, in the 2-, 3-, 4 - and/or 7-positions. Preferred bridges are ethylene or SiMe2.

Getting metallocenes can be performed according or analogously to methods known from the literature, and within the competence of the specialist in this field. Thus, obtaining see, for example, in EP-A-129368, examples of compounds in which the metal atom bears- R2"the ligand, see, among others, in WO-A-9856831 and WO-A-0034341. Receiving, see also EP-A-260130, WO-A-9728170, WO-A-9846616, WO-A-9849208, WO-A-9912981, WO-A-9919335, WO-A-9856831, WO-A-00/34341, EP-A-423101 and EP-A-537130.

Alternatively, additional subgroup metallocene compounds metal carries the Cf group, as defined above, and optionally η1 or η2 ligand, where these ligands can be connected or not connected bridge communication with each other. Such compounds are described, for example, in WO-A-9613529, the content of which is incorporated herein by reference.

More preferred metallocene include compounds of formula (I)

Cp2'HfX2',(I)

where each X' is halogen, C1-6the alkyl, benzyl or hydrogen;

Cf' is cyclopentadienyls or indenolol group, optionally substituted C1-10hydrocarbon group or groups and, if necessary, connected by bridge connection, for example, by ethylene or dimethylsilane.

Especially preferred catalysts are dichloride, bis(n-butylcyclopentadienyl)hafnium, dichloro the d bis-(n-butylcyclopentadienyl)zirconium and dibenzyl bis-(n-butylcyclopentadienyl)hafnium, the latter is especially preferred.

The metallocene precatalysts usually used as part of the catalytic system, which also includes an activator, a catalyst, also called socialization. Suitable activators are, among others, are aluminum compounds, such compounds alkoxyamine. Suitable alkoxyamine activators are, for example, methylalumoxane (MAO), examsolutions and tetraisostearate. Moreover, as activators you can use boron compounds (for example, connection forbore, such as triphenylmethane or triphenylcarbenium-tetraphenylnaphthalene ((C6H5)3In+In-(C6P5)4)). Socializaton and activators and the receipt of such catalytic systems are well known in the prior art. For example, when the activator is used alkoxyamine compound, the molar ratio Al/M of the catalytic system (Al represents aluminum from activator and M is a transition metal complex of the transition metal) ranges from 50 to 500 mol/mol, preferably from 100 to 400 mol/mol. It is also possible relationship below or above these ranges, however, the above ranges are often the most appropriate.

If you want to precatalysts, you can ispoljzovalosj precatalysts/acetalization or reaction product precatalysts/socialization applied in the form (for example, on the media from silicon dioxide or aluminum oxide), nenalezena form or it can be precipitated and used as such. One possible way to obtain a catalytic system based on emulsion technology that does not use any external media, however, the solid catalyst is formed by curing catalyst droplets dispersed in the continuous phase. The method of curing and additional possible metallocene described, for example, in WO 03/051934, which is incorporated herein by reference.

It is also possible to use combinations of different activators and proletarization. Moreover, as is known in the prior art, it is possible to use additives and modifiers and similar substances.

Any catalytically active catalytic system, including precatalysts, for example, metallocene complex, here called metallocene catalyst (system) with one active center.

Getting stitched polymer

To obtain the ethylene polymer of the present invention can be used methods of polymerization are well known to the specialist. The protection scope of the invention includes a multi-modal, for example, at least bimodal polymer obtained by mixing each component in situ during its polymerization method (the so-called method of in situ) or, as ternative, by mechanical mixing of two or more received separately components method known in the prior art. Multimodal polymer suitable for the present invention, preferably prepared by mixing in situ in the multistage polymerization method. Accordingly, the polymers are obtained by mixing in situ in multiple steps, i.e. consisting of two or more stages, the polymerization method, including the methods in the solution, slurry and gas phase in any order. Although it is possible to use different catalysts with one active site in each stage of the method, preferably, if used, the catalyst is the same in both stages.

Therefore, ideally, a polyethylene polymer according to the invention receives at least two-stage polymerization using the same catalyst with one active center. Thus, it is possible to apply, for example, two suspension reactor or two gas-phase reactor, or any combination in any order. However, preferably polyethylene is produced using the suspension polymerization in a loop reactor followed by a gas-phase polymerization in the gas-phase reactor.

System loop reactor gas-phase reactor is well known as the Borealis technology, that is, as BORSTAR™ reactor system. This multi-stakeholder who atiny method described, for example, in EP 517868.

Used in this way conditions are well known. For slurry reactors, the reaction temperature is usually from 60 to 110°C., for example, 85-110°C, the pressure in the reactor is usually from 500 kPa to 8 MPa (5 to 80 bar), for example, 5-6,5 MPa (50 to 65 bar), and time is usually from 0.3 to 5 hours, for example from 0.5 to 2 hours. Used diluent is usually aliphatic hydrocarbon having a boiling point of from -70 to +100°C, for example, propane. In such reactors, the polymerization can be performed, if required, under supercritical conditions. The suspension polymerization can also be performed in the volume, where the form of the reaction environment of the polymerized monomer.

For gas-phase reactor is used, the reaction temperature is usually from 60 to 115°C., for example, from 70 to 110°C., the pressure in the reactor is usually from 1 to 2.5 MPa (from 10 to 25 bar), and time is usually from 1 to 8 hours. The gas used is usually directionspanel gas, such as nitrogen or hydrocarbons with low boiling point, such as propane, together with a monomer, such as ethylene.

Control degree of polymerization, preferably hydrogen, can be added as needed in the reactor. It is preferable if the amount of hydrogen used by the CSOs receiving the first component, very little. Therefore, it is preferable to add an amount less than 1 mole, preferably less than 0.5 mole, for example, from 0.01 to 0.5 mol H2on kilomole of ethylene in the first, for example a loop reactor.

The amount of hydrogen added to the second reactor, usually gas-phase reactor, also very small. Values can be from 0.05 to 1, for example, of 0.075 to 0.5, mainly from 0.1 to 0.4 mol H2on kilomole of ethylene.

The concentration of ethylene in the first loop preferably, the reactor may be from about 5 to 15 mole.%, for example, from 7.5 to 12 mole.%.

In the second, preferably of the gas, the reactor, the concentration of ethylene is preferably much higher, for example at least 40 mole.%, such as from 45 to 65 mole.%, preferably from 50 to 60 mole.%.

Preferably the first polymer fraction is obtained in a continuously operating loop reactor in which ethylene will polimerizuet in the presence of an installed above polymerization catalyst and regulator of the degree of polymerization, such as hydrogen. The diluent is typically an inert aliphatic hydrocarbon, preferably isobutane or propane. The reaction product is then moved, preferably in a continuously operating gas-phase reactor. Then it is possible to form the second component in the gas-phase reactor, preferably ispolzuyet catalyst.

The polymerization method may be preceded by preliminary polymerization.

The use of partial pressures in this range is an advantage and forms an additional embodiment of the invention therefore provides a method of obtaining a multimodal ethylene polymer, including:

(1) polymerization of ethylene and, optionally, at least one of the co monomer in the first stage in the presence of a catalyst and an active centre and at a partial pressure of ethylene, from 5 to 15 mole.%;

(2) polymerization of ethylene and, optionally, at least one of the co monomer, the second stage in the presence of the same catalyst with one active site and at a partial pressure of ethylene and 45 mole.%;

with the formation of the above-described ethylene polymer.

The ethylene polymer according to the invention can be mixed with any other target polymer or use by itself as a single olefinic material in the product. Thus, the ethylene polymer according to the invention can be mixed with known HDPE (high density polyethylene), PASP (medium-density polyethylene), LDPE (low density polyethylene), LLDPE (linear low-density polyethylene) polymers, or you can use a mixture of ethylene polymers according to the invention. However, ideally, any product manufactured by the th of the ethylene polymer according to the invention, essentially consists of a polymer, i.e. contains ethylene polymer along only with standard polymer additives.

The ethylene polymer according to the invention can be mixed with standard additives, fillers and activating additives known in the prior art. It may also contain additional polymers, such as polymers carrier extra uterine mixtures. Preferably the ethylene polymer comprises at least 50 wt.% any polymeric composition containing the ethylene polymer, preferably from 80 to 100 wt.%, and more preferably from 85 to 100 wt.% in relation to the total weight of the composition.

Suitable antioxidants and stabilizers are, for example, sterically difficult phenols, phosphates or phosphonites, sulfur-containing antioxidants, alkyl acceptors radicals, aromatic amines, sterically difficult amine stabilizers and mixtures containing compounds of two or more of the above groups.

Examples of sterically obstructed phenols are, among others, 2,6-ditretbutyl-4-METHYLPHENOL (supplied, for example, by Degussa under the trade name lonol CF), pentaerythrityl-tetrakis(3-(3',5'-ditretbutyl-4-hydroxyphenyl)propionate (supplied, for example, Ciba Specialty Chemicals under the trade name Irganox 1010), octadecyl-3-3(3',5'-ditretbutyl-4'-hydroxy is enyl)propionate (supplied, for example, Ciba Specialty Chemicals under the trade name Irganox 1076) and 2,5,7,8-tetramethyl-2(4',8',12'-trimethylacetyl)chroman-6-ol (supplied, for example, by BASF under the trade name Alpha-Tocopherol).

Examples of phosphates and phosphonites are Tris(2,4-ditertbutyl)fosfat (supplied, for example, Ciba Specialty Chemicals under the trade name Irgafos 168), tetrakis-(2,4-ditertbutyl)-4,4'-biphenylenediisocyanate (supplied, for example, Ciba Specialty Chemicals under the trade name Irgafos P-EPQ) and Tris-(nonylphenyl)phosphate (supplied, for example, Dover Chemical under the trade designation Doverphos HiPure 4).

Examples of sulfur-containing antioxidants are delayintolerant (supplied, for example, Ciba Specialty Chemicals under the trade name Irganox PS 800) and distearyldimethylammonium (supplied, for example, Chemtura under the trade name Lowinox DSTDB).

Examples of nitrogen-containing antioxidant is 4,4'-bis(1,l-dimethylbenzyl)diphenylamine (supplied, for example, Chemtura under the trade name Naugard 445), a polymer of 2,2,4-trimethyl-1,2-dihydroquinoline (supplied, for example, Chemtura under the trade name Naugard EL-17), n-(p-toluensulfonyl)-diphenylamine (supplied, for example, Chemtura under the trade name Naugard SA) and N,N'-diphenyl-p-phenylenediamine (supplied, for example, Chemtura under the trade name Naugard J).

Also available industrial supply is MESI antioxidants and stabilizers process, such as Irganox B225, Irganox B215 and Irganox B561 sold by Ciba Specialty Chemicals.

Suitable absorbers acids are, for example, metallic stearates such as calcium stearate and zinc stearate. They are used in amounts generally known in the prior art, typically from 500 parts per million to 10,000 parts per million, and preferably from 500 parts per million to 5,000 parts per million

The most commonly used colorant is carbon black, which also acts as a reflector of UV radiation. Usually, carbon black is used in amounts of from 0.5 to 5 wt.%, preferably from 1.5 to 3.0 wt.%. Preferably the carbon black is added in the form of a concentrate of a dye mixture in which it is pre-mixed with a polymer, preferably a high density polyethylene (HDPE), in a specific quantity. Suitable concentrates coloring mixture are, among others, HD4394 supplied by Cabot Corporation, and RM from Poly Plast Muller. Also as a reflector of UV radiation it is possible to use titanium oxide.

The application

The polymer according to the invention is stitched and perfect for use in the formation of cross-linked pipes. Crosslinking of the polymer/tubes can be achieved by conventional methods, for example using peroxide, irradiation or silane cross-linking agents. When crosslinking by peroxide crosslinking occurs by addition of peroxide compounds which form free the radicals. Crosslinking can also be achieved by irradiation or by using silanes. However, preferably, if the pipe according to this invention is produced by radiation crosslinking. Pipe according to the invention are preferably PE-X pipes (pipes made of cross linked polyethylene).

When a predefined amount of exposure you can use a polymer with a lower molecular weight (higher P)than in the previous prior art. According to the present invention is the lack of tail fraction with very low molecular weight of the polymers obtained in the presence of a catalyst with one active site, leading to improved stevenote.

Polymers with a low molecular weight require a higher amount of peroxide to achieve effective cross stitched patterns.

Radiation cross-linking is preferred, and can be done by firing a formed tube electron beam. Used the dose can be changed, however, suitable dosage ranges from 100 to 200 kGy (gray), for example from 150 to 200 kGy. Specific target dose of 160 kGy and GSR 190.

The polymers according to the invention can show the degree of crosslinking (i.e., stevenote) at least 60%, such as at least 65%. In particular, the ethylene polymer according to the invention may have a degree of crosslinking ≥60%, measured opican is m below.

The ethylene polymer according to the invention therefore can show the degree of crosslinking of at least 60% when tested as described below regulated procedures, that is, when forming the obtaining of the pipe, as set forth below regulated procedure under the heading "radiation pipe", and the degree of crosslinking was measured by extraction decaline (measured according to ASTM D2765-01, Method A). However, it should be emphasized that the ethylene polymer according to the invention does not have to be made.

In the preferred embodiment of the invention provides crosslinked multimodal ethylene polymer with a density of less than 950 kg/m3obtained by polymerization in the presence of a catalyst and an active centre, and with

P21from 10 to 20 g/10 min,

the rate of decrease in viscosity when the shear PSV2,7/210at least 4, and preferably

stevenote at least 60%,

and made of it a pipe.

Pipe according to the invention also show a degree of crosslinking of at least 60%.

Pipe of the present invention receive in accordance with methods known in the art. Thus, one preferred method the polymer composition ekstragiruyut across the head with the annular nozzle to the desired internal diameter, after which the polymer to the cool position.

Preferred are extruders having a high ratio of length to diameter L/D greater than 15, preferably at least 20 and especially at least 25. Modern extruders typically have a ratio L/D of from about 30 to 35.

Polymer melt ekstragiruyut across the head with the annular nozzle, which may be located either in a configuration with end feed, either in a configuration with side feed. Head with lateral flow is often fixed so that their axis is parallel to the axis of the extruder, which requires turning at a right angle in accession to the extruder. The advantage of the head-side feed is that the core can be pulled through the head and this ensures, for example, easy access to piping systems with cooling water to the core.

After the molten polymer exits the head, it is calibrated to the correct diameter. In the same way the extrudate is directed to a metal pipe (the calibration sleeve). Inside the extrudate is subjected to increased pressure so that the polymer was pressed against the pipe walls. The tube is cooled using a shirt, or by passing above the cold water.

According to another method, water-cooled extension piece attached to the end of the mandrel head. Water-cooled extension thermally isolated from the mandrel head is exercised by the cooling water, circulating through the mandrel head. The extrudate pull on the core, which determines the shape of the pipe and maintains that form during cooling. Cold water is passed over the external surface of the pipe to cool.

According to another method, coming from the head extrudate is directed into a pipe having a perforated section in the center. Through the perforations provide a weak vacuum to hold the trumpet at the walls of the calibration chamber.

After calibration, the pipe is cooled, typically in a water bath having a length of about 5 meters or more.

Pipe according to the present invention preferably satisfy the requirements of the standard RE, as defined in EN 12201 and EN 1555, alternative ISO 4427 and ISO 4437, the evaluation according to ISO 9080. Particularly preferably, the pipe meets the requirements of EN ISO 15875.

Typically, polymer pipes are manufactured by extrusion. Traditional installation for screw extrusion of pipes made of PE-X polymers include single or twin screw extruder nozzle, the calibration device, cooling equipment, lingering device and a device for cutting or coagulation tubes. The polymer ekstragiruyut with getting the pipe from the extruder, after which the pipe sew. This technology screw extrusion is well known in the art, and therefore it does not require any additional the different details. The ethylene polymers according to the invention are particularly suitable for screw extrusion process.

The high degree of crosslinking and other properties of the ethylene polymer according to the invention enables the formation of products, in particular tubes, which have excellent surface quality, i.e. have no defects and are smooth to the touch.

Pipe according to the invention is particularly suitable for conveying water, especially hot water.

It should be understood that what is described here is the preferred characteristics of the polymers according to the invention can be combined with each other in any way.

The invention is hereinafter described with reference to the following non-limiting it to the examples.

Analytical testing

The rate of flow of the melt

The rate of melt flow (P) is determined according to ISO 1133, and denote g/10 min. P is a measure of the viscosity of a polymer melt. For polyethylene P is determined at 190°C. the Load, which determines the rate of flow of the melt, usually shown as a subscript, for example CTP2measured under a load of 2.16 kg (condition D), CTP5measured at a load of 5 kg (condition T) or CTP21measured under a load of 21.6 kg (condition G).

The value of MRA (ratio of mass flow rate) is a measure of molecular mass distribution and denotes the ratio of the mass flow rates of p and different loads. Thus, OMR/2 denotes the value of the CTP21/CTP2.

Density

The density of the polymer was measured according to ISO 1183/1872-2B.

For the purposes of this invention the density of the mixture can be calculated based on the densities of the components according to the formula:

ρb=∑iwi·ρi,

ρbis the density of the mixture,

wiis the mass fractions of component i in the mixture, and

ρiis the density of component "i".

Molecular mass

Mw, Mn and DFID is measured by means of gel chromatography (GPC) according to the following method.

The mass-average molecular weight Mw and the molecular-mass distribution (MMD=Mw/Mn, where Mn is srednekamennogo molecular weight and Mw is the mass-average molecular weight) measured according to ISO 16014-4:2003 and ASTM D 6474-99. The instrument Waters GPCV2000 sensor equipped refractive index and the viscometer operating in real time, used with 2×GMHXL-HT and 1×G7000HXL-HT TSK gel columns from Tosoh Bioscience and 1,2,4-trichlorobenzene (TCB, stabilized with 250 mg/l 2,6-ditretbutyl-4-METHYLPHENOL) as solvent at 140°C and a constant mass flow rate of 1 ml/min of 209.5 ál of the sample solution was injected for analysis. Columns were calibrated using universal calibration (according to ISO 16014-2:2003) at least 15 polystyrene (PS) with whom the standards with a narrow MMD in the range from 1 kg/mol to 12000 kg/mol. Permanent Brand Hoinka used, as described in ASTM D 6474-99. All samples were made by dissolving 0.5 to 4.0 mg of polymer in 4 ml (140°C) stabilized TCB (coinciding with the mobile phase) and during a storage period of not more than 3 hours at a maximum temperature of 160°C With continuous light shaking prior to placing the sample into the GPC instrument.

As is known in the prior art, the mass-average molecular mass of the mixture can be calculated if you know the molecular weight of its components, according to the formula:

Mwb=∑iwi·Mwi,

where Mwbis the mass-average molecular weight of the mixture,

wiis the mass fraction of component "i" in the mixture, and

Mwiis the mass-average molecular weight of component "i".

Srednekamennogo molecular weight can be calculated using the well-known formula:

1/Mnb=∑iwi/Mni,

where Mnbis srednekamennogo molecular weight of the mixture,

wiis the mass fraction of component "i" in the mixture, and

Mniis srednekamennogo molecular weight of component "i".

Rheology

Rheological parameters such as the rate of decrease in viscosity when the shear PSV and the viscosity is determined using a rheometer, preferably Anton Paar Physica MCR 300 Rheometer on compression molded samples the nitrogen atmosphere at 190°C. using flat disks with a diameter of 25 mm and disk geometry with a gap of 1.8 mm according to ASTM 1440-95. Experiments on pulsed shift was performed within the linear range of the viscosity of mechanical stress at frequencies from 0.05 to 300 rad/s (ISO 6721-1). It was made five measurement points per decade. In detail the method described in WO 00/22040.

Were obtained the values of dynamic modulus of elasticity (G'), loss modulus (G”), the aggregate modulus (G*) and complex viscosity (η*) as a function of frequency (ω).

The rate of decrease in viscosity shear (PSV), which correlates with MMP and does not depend on Mw, calculated according to Heino ("Rheological characterization of polyethylene fractions", Heino E.L, Lehtinen, A., Tanner J., Seppälä J., Neste Oy, Porvoo, Finland, Theor. Appl. Rheol., Proc. Int. Congr. Rheol., 11th (1992), 1, 360-362 and "The influence of molecular structure on some rheological properties of polyethylene", Heino E.L., Borealis Polymer Oy, Porvoo, Finland, Annual Transactions of the Nordic Rheology Society, 1995.).

The PSV value is obtained by calculating the complex viscosities at these values, the total module, calculating the ratio of the two viscosities. For example, using values of total module 2,7 kPa and 210 kPa, then get η*(2.7 kPa) and η*(210 kPa) at a constant value of the total module 2,7 kPa and 210 kPa, respectively. The rate of decrease in viscosity when the shear PSV2,7/210then determine the ratio of the two viscosities η*(2.7 kPa) and η*(210 kPa), i.e. η(2,7)/η(210).

It is not always possible on the right is the tick directly measure the complex viscosity at low frequency value. This value can be extrapolated by measuring to the frequency 0,126 rad/s by drawing a graph of complex viscosity versus frequency on a logarithmic scale by drawing a straight line with the least quadratic deviation of the five points corresponding to the lowest frequency values, and calculating the viscosity of the line.

The yellowness index

The yellowness index (PI) is a number calculated from the data spectrophotometry, which describes the change in color of a test specimen from light or white to yellow. This test is most often used to assess changes in the color of the material, caused by a real or simulated exposure under the conditions of the external environment. Spectrophotometric device is a Spectraflash SF600 software ColorTools, which computes a measure of yellowness E according to ASTM E313. The sample tubes were tested on the sample holder.

The yellowness index is classified as follows:

1,5-6,5
Class 1Class 2Class 3Class 4
Mud according to ASTM E313<(-0,9)(-0,9)-1,5>6,5

Ash

For ash content <1000 parts per million use the so-called "method of combustion".

- Heated two pure platinum Cup at 870°C for 15 minutes and then cool them to room temperature in the dryer.

- Measure the weight of the cups immediately after the dryer to the nearest 0.1 mg.

- Give 15 g of the polymer powder in a platinum Cup (accurate to 0.1 mg) (after sieving powder).

- Burn the powder into the device for burning up until will not burn all the material, that is, until, until you turn off the flame.

- Put the Cup in the kiln at 870°C for 45 minutes.

- Cool Cup in the dryer to room temperature and measure the weight of the cups to the nearest 0.1 mg.

- Weight of ash is a mass of Cup with ash minus the mass of the empty Cup.

- Calculation of ash content: (g ash/g polymer sample)×100 = wt.% ash content.

Irradiation tubes

Polymer powders were mixed and granulated in the installation Buss 100 mm. The pipe extrusion was performed in the extruder Battenfeld using standard PE screw. The melt temperature ranged from 200 to 230°C. the dimensions of the tube was 20×2 mm, Irradiation tubes was performed by an electron beam at room temperature in air using a dose of 160 kGy.

The degree of crosslinking, school %

School %measured by detalirovki extraction (measured according to ASTM D 2765-01, Method (A).

Example 1 preparation

Preparation of catalyst

The catalytic complex used in the examples of polymerization, represented bis(n-butylcyclopentadienyl)hafnium dibenzyl, (n-BuCp)2Hf(CH2Ph)2and his prepared according to Example 2 preparation of catalyst" WO 2005/002744, on the basis of the dichloride bis(n-butylcyclopentadienyl)hafnium (supplied by Witco).

The preparation of the catalyst was carried out in 160 l reactor batch, which was added to the solution of metallocene complex. The mixing speed was 40 rpm during the reaction and 20 rpm during drying. The reactor was thoroughly washed with toluene until the reaction was purged with nitrogen after addition of silicon dioxide.

Activated catalytic system

10,0 kg of activated silica (industrial media from silicon dioxide, HROA having an average particle size of 20 μm, supplier: Grace) suspended 21.7 kg of dry toluene at room temperature. Then the suspension of silicon dioxide was added to 14,8 kg 30 wt.% methylalumoxane in toluene (MAO, supplied by Albemarle) for 3 hours. Then the mixture MAO/silica was heated to 79°C for 6 hours and then cooled again to room temperature.

The resulting solution was reacted with 0.33 kg (n-BuCp)2Hf(CH2Ph)2in Tolu is Le (67,9 wt.%) within 8 hours at room temperature.

The catalyst was dried by purging with nitrogen for 5.5 hours at 50°C.

The resulting catalyst had a molar ratio Al/Hf 200, Hf concentration of 0.44 wt.% and the Al concentration of 13.2 wt.%.

Preparation of catalyst 2

The catalytic system is based on the complex bis(n-butylcyclopentadienyl)hafnium of dibenzyl (n-BuCp)2HfBz2. The catalytic system is prepared according to the principles described in WO 03/051934 as set forth below:

In fitted shirt 90 DM3the reactor of stainless steel, coated inside with the enamel, to prepare a solution of the complex at -5°C, adding very slowly (3.4 ml/min) of 1.26 kg 24.5 wt.% solution PFPO ((2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-heptadecadiene)oxiran) in toluene to 20 kg 30 wt.% solution methylalumoxane in toluene. The temperature was raised to 25°C and the solution was stirred for 60 minutes. After adding 253 g of complex (Hf content of 78.8 wt.% in toluene), the solution was stirred for another two hours. This mixture was pumped at a speed of 5 l/h in the rotor-stator with a pair of 4M rotor-stator. In the rotor-stator peripheral speed of the end vanes 4 m/s and the mixture was mixed with a flow of 32 l/h, PFC (hexadecafluoro-1,3-dimethylcyclohexane), thus forming the emulsion. Droplets in the emulsion utverjdali through excess flow 450 l/h PFC at 60°C in a Teflon flexible pipe. Flexible Tr is borrowed was connected with a fitted shirt 160 DM 3a reactor of stainless steel, equipped with a helical mixing element. In this reactor the catalyst particles separated from the PFC by the difference in their densities. After that utilized the solution of the complex, the catalyst particles were dried at 160 DM3reactor at a temperature of 70°C and a flow of nitrogen of 5 kg/h for 4 hours.

The resulting catalyst had a ratio Al/Mt, equal to 300, the Hf content of 0.7 wt.% and the Al content 34.4 wt.%.

Examples of polymerization

The two-stage polymerization

Loop reactor having a volume of 500 DM3operated at 85°C and a pressure of 5.8 MPa (bar 58). Into the reactor were introduced propane diluent, hydrogen and ethylene. The polymerization catalyst prepared according to the above description, continuously introduced into the reactor in order to achieve the following output.

The polymer slurry was removed from the loop reactor and moved into the evaporation vessel, operating at pressures of 300 kPa (3 bar) and a temperature of 70°C, in which the hydrocarbons were essentially removed from the polymer. The polymer is then introduced into the gas-phase reactor operating at a temperature of 80°C and pressure of 2 MPa (20 bar). Additional ethylene, hexene, and hydrogen was introduced into the reactor. Conditions shown in table 1.

Polymers were obtained in the de powder. Properties of the formed polymer and crosslinked pipes are presented in table 2.

Table 2
DesignationPolymer 1Polymer 2
Density (kg/m3)946,5943,4
η0,05pandd/with a*(PA·s)1830021400
η5KPand*(PA·s)1620018700
CTP21(g/10 min)1413
P5(g/10 min)1,51,4
Mw (g/mol)157000165000
Mn (g/10 mol)3390038700
Mw/Mn4,64,3
PSV5/3006,16,2
PSV2,7/210the 4.7a 4.9
Surface qualityGoodGood
School, % (exposed. 160 kGy)>62>60
Ash content (parts/million)300190

The low activity of the catalyst is obviously not desirable either from the point of view of economy of way, neither from the point of view of product quality, because it leads to high salesteam in the polymer. The high ash content lead to undesirable characteristics, such as yellow, gels, etc. In table 3 show that the ash content should be kept below the range 250-500 parts per million

Table 3
The yellowness index depending on the ash content of the polymer SSC in the form of pipes
The yellowness indexAsh (h is the capacity per million)
1<250
3540
4710
41680
42765

1. Cross-linked polyethylene, comprising a multimodal ethylene polymer with a density of less than 950 kg/m3obtained by polymerization in the presence of a catalyst and an active center, and with the rate of flow of the melt CTP21from 10 to 20 g/10 min;
the rate of decrease in viscosity when the shear PSV2,7/210at least 4;
which is sewn.

2. Cross-linked polyethylene according to claim 1, comprising a multimodal ethylene polymer having a density of 940 to less than 950 kg/m3.

3. Cross-linked polyethylene according to claim 1, comprising a multimodal ethylene polymer having an ash content of less than 350 million hours

4. Cross-linked polyethylene according to claim 1, comprising a multimodal ethylene polymer having a degree of crosslinking, as measured by extraction with decaline, at least 60%.

5. Cross-linked polyethylene according to claim 1, comprising a multimodal ethylene polymer having a component homopolymer ethylene with a lower molecular weight component copolymer of ethylene with a higher molecular weight.

6 cross-linked polyethylene according to claim 5, comprising a multimodal ethylene polymer having a component homopolymer ethylene with a lower molecular weight component copolymer of ethylene and hexene with higher molecular weight.

7. Cross-linked polyethylene according to claim 1, comprising a multimodal ethylene polymer having a Mw/Mn of at least 4.

8. Cross-linked polyethylene according to any one of claims 1 to 7, having a degree of crosslinking of at least 60%.

9. Custom made pipe, including cross-linked polyethylene according to any one of claims 1 to 8.

10. Custom made pipe according to claim 9, crosslinked by irradiation.

11. Stitched tube of claim 10, where this pipe has a degree of crosslinking of at least 60%.

12. The multimodal ethylene polymer with a density of less than 950 kg/m3obtained by polymerization in the presence of a catalyst with one active site, and have
P21from 10 to 20 g/10 min;
the rate of decrease in viscosity when the shear PSV2,7/210at least 4 in the manufacture of custom made pipes.

13. Multimodal ethylene polymer with a density in the range from 940 to less than 950 kg/m3obtained by polymerization in the presence of a catalyst with one active site, and have
CTP21from 10 to 20 g/10 min;
the rate of decrease in viscosity when the shear PSV2,7/210at least 4; which is crosslinked and has a component of homopolymer ethylene with a lower molecular mass and component copolymer of ethylene with a higher molecular weight.

14. A method of obtaining a multimodal ethylene polymer, including:
(1) polymerization of ethylene in the first stage in the presence of a catalyst with one active site, preferably deposited on silicon dioxide or which is a solid catalyst formed by the solidification of the droplets of the catalyst dispersed in the continuous phase;
(2) polymerization of ethylene and at least one of the co monomer in the second stage in the presence of the same catalyst with one active center;
to obtain the ethylene polymer according to any one of claims 1 to 8.

15. Polymer composition comprising a multimodal ethylene polymer according to item 13 and at least one additive and/or other olefinic component.



 

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3 dwg

FIELD: chemistry.

SUBSTANCE: multimodal copolymer of ethylene and one or more alpha-olefins containing 4-10 carbon atoms is characterised by density of 937-950 kg/m3, flow melt index STR5 of 0.5-2.0 g/10 min, flow melt index STR2 of 0.2-1.0 g/10 min, and shear thinning index IUVS2.7/210 of 0.3-20. The multimodal copolymer contains 30-70 wt % low-molecular weight ethylene polymer, selected from an ethylene homopolymer and a copolymer of ethylene and one or more alpha-olefins containing 4-10 carbon atoms, and is characterised by weight-average molecular weight of 5000-100000 g/mol and density of 960-977 kg/m3, and 30-70 wt % copolymer of high-molecular weight ethylene and one or more alpha-olefins containing 4-10 carbon atoms, and is characterised by average molecular weight of 100000-1000000 g/mol and density of 890-929 kg/m3.

EFFECT: compositions are flexible; tubes made therefrom can be easily bent or coiled into a ring; the tubes are characterised by sufficient mechanical strength, which enables their use under pressure.

15 cl, 1 dwg, 3 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention relates to fibre made from a polyethylene composition, a method of making said fibre, fabric made from said fibres and a method of making said fabric. The fibre is made from a polyethylene composition which contains at least 80 wt % of a (co)polymer, which contains at most 100 wt % links obtained from ethylene and less than 20 wt % links of one or more α-olefin comonomers. The composition has density of 0.920-0.970 g/cm3, molecular weight distribution (Mw/Mn) of 1.70-3.5, flow melt index (I2) of 0.2-1000 g/10 min, molecular weight distribution (Mz/Mw) of less than 2.5 and vinyl unsaturation level of less than 0.1 vinyl groups per thousand carbon atoms present in the backbone chain of said composition. The disclosed fibre can have denier value per filament less than 50 g/9000 m, breaking strength of 0.1-15 g/denier and relative elongation less than 1500%.

EFFECT: fabric made from said fibre, both woven and nonwoven, have high tearing strength, improved softness and drapeability.

10 cl, 4 dwg, 10 tbl

FIELD: chemistry.

SUBSTANCE: polymer composition contains a mixture of (i) a polymer selected from polyethylene, polypropylene, polystyrene, polyvinyl chloride or a mixture thereof (ii) cellulose, (iii) ammonium nitrate, (iv) nutrients selected from blue-green algae and/or yeast, and (v) water. This composition can be mixed with a pure base polymer to obtain a polymer master batch. The master batch of the composition can be mixed with a pure base polymer which is suitable for obtaining products which are biodegradable. Described also is a method of preparing a biodegradable polymer composition, a method of preparing a master batch of the biodegradable polymer composition.

EFFECT: biodegradation of the composition within 6 to 36 months, environmental safety, preparation of the biodegradable composition does not require special equipment.

15 cl, 27 ex

FIELD: chemistry.

SUBSTANCE: multimodal ethylene copolymer has density of 924-960 kg/m3, melt flow index STR5 of 0.5-6.0 g/10 min, melt flow index STR2 of 0.1-2.0 g/10 min and shear thinning index IUVS2.7/210 of 2-50. The multimodal ethylene copolymer contains at most 100 ppm by weight of volatile compounds. The multimodal ethylene copolymer is obtained in two steps by polymerisation in the presence of a catalyst with a single polymerisation centre of ethylene, hydrogen and one or more alpha-olefin having 4-10 carbon atoms. A low-molecular weight component (A) of the ethylene polymer is obtained in a first polymerisation zone and a high-molecular weight component of the ethylene copolymer (B) is obtained in a second polymerisation zone. The first and second polymerisation steps can be carried out in any order and the next step is carried out in the presence of a polymer obtained at the previous step. Components (A) and (B) are present in the multimodal ethylene copolymer in amount of 30-70 wt % and 70-30 wt %, respectively, of the total amount of components (A) and (B). Component (A) has weight-average molecular weight of 5000-100000 g/mol and density of 945-975 kg/m3, and component (B) has weight-average molecular weight of 100000-1000000 g/mol and density of 890-935 kg/m3.

EFFECT: improved properties of the compound.

15 cl, 1 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: film contains multilayered antioxygen barrier component, in which: i) active antioxygen barrier layer is located between two passive antioxygen barrier layers, or ii) passive antioxygen barrier layer is located between two active antioxygen barrier layers. Active layer contains oxygen-absorbing composition, which represents mixture of thermoplastic resin (A) with carbon-carbon double bonds mainly in main chain, salts of transition metal (B) and antioxygen barrier polymer (C). Passive layer contains material selected from group, including copolymer of ethylene and vinyl alcohol, polyvinyl alcohol and their copolymers and combinations. Multilayered antioxygen barrier component is located between sealing layer and stable to external impact layer. Invention also relates to package, containing food product and said film. Passive antioxygen barrier layers assist in preservation of antioxygen barrier properties of film after depletion of capacity to absorb oxygen of active barrier layer.

EFFECT: increased term of film service life.

9 cl, 6 dwg, 3 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: pipe is made from spatially cross-linked polyolefin composition which is obtained by cross-linking a polyolefin composition. The polyolefin composition contains a base resin which contains a cross-linkable olefin homo- or copolymer (A) which contains hydrolysable silicon-containing groups, and filler (B). The filler is selected from mineral glass filler, feldspar, barites and carbon fibres.

EFFECT: disclosed pipe has significantly improved hardness and modulus of elasticity in tension.

13 cl, 2 tbl

FIELD: chemistry.

SUBSTANCE: ethylene copolymers and a method of producing said copolymers are provided. More specifically, provided are ethylene copolymers which exhibit excellent processability and physical properties due to their polydispersity index of polymodal molecular weight distribution, achieved via a multi-step process using reactors which are connected in series or in parallel. The method involves: a) solution polymerisation of ethylene and C3-C18 α-olefin comonomer(s) in the presence of a catalyst composition containing a transition metal catalyst of chemical formula (1) and a cocatalyst; (b) passing a first copolymer synthesised at step (a) through at least another reactor containing ethylene or ethylene and at least one C3-C18 α-olefin, at temperature 90-220°C and pressure 20-500, at temperature higher than the reaction temperature at step (a) in the presence of the same catalyst composition as was used at step (a) to obtain a polymer at high temperature, which contains a copolymer combination of ethylene and C3-C18 α-olefin. In the second version of the method, copolymers from step (a) and (b) are obtained separately and (c) the first copolymer from step (a) is mixed with the second copolymer from step (b).

EFFECT: disclosed is an ethylene copolymer for making extrusion blown films, films made by casting, articles made by injection moulding, articles made by blow moulding or tubes made using said methods, wherein radicals and symbols assume values given in the claim.

14 cl, 3 dwg 4 tbl, 11 ex

FIELD: chemistry.

SUBSTANCE: multimodal copolymer of ethylene and one or more alpha-olefins containing 4-10 carbon atoms is characterised by density of 937-950 kg/m3, flow melt index STR5 of 0.5-2.0 g/10 min, flow melt index STR2 of 0.2-1.0 g/10 min, and shear thinning index IUVS2.7/210 of 0.3-20. The multimodal copolymer contains 30-70 wt % low-molecular weight ethylene polymer, selected from an ethylene homopolymer and a copolymer of ethylene and one or more alpha-olefins containing 4-10 carbon atoms, and is characterised by weight-average molecular weight of 5000-100000 g/mol and density of 960-977 kg/m3, and 30-70 wt % copolymer of high-molecular weight ethylene and one or more alpha-olefins containing 4-10 carbon atoms, and is characterised by average molecular weight of 100000-1000000 g/mol and density of 890-929 kg/m3.

EFFECT: compositions are flexible; tubes made therefrom can be easily bent or coiled into a ring; the tubes are characterised by sufficient mechanical strength, which enables their use under pressure.

15 cl, 1 dwg, 3 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: composition contains a polyolefin polymer matrix containing a propylene homopolymer with MWD (molecular weight distribution) of 1.5-5.0 and copolymer of ethylene with one or more comonomers selected from alpha-olefins with 4-12 carbon atoms, having density of not more than 920 kg/m3. The weight ratio of the propylene homopolymer to the copolymer of ethylene in the polyolefin polymer matrix ranges from 95:5 to 60:40. The propylene homopolymer is polymerised in the presence of a catalyst with a single cross-linking point, where the cold xylene-soluble fraction is not more than 2 wt %. The disclosed composition has good mechanical properties, particularly impact resistance at low temperatures and bending properties, without the need to use special equipment to prepare the mixture and/or additives when producing said compositions.

EFFECT: articles made from the composition have good scratch resistance along with low lustre.

14 cl, 3 tbl, 10 ex

FIELD: chemistry.

SUBSTANCE: invention relates to polyethylene moulding composition having multimodal molecular-weight distribution for making tubes. The composition contains the following in wt %: a first low-molecular weight ethylene homopolymer A 45-55; a second high-molecular weight copolymer B 20-40 containing ethylene and one more olefin with 4-8 carbon atoms; a third ethylene copolymer C 15-30. The composition further contains an organic polyoxy-compound in amount of 0.01-0.5 wt %. The composition is obtained in the presence of a Ziegler catalyst using a three-step suspension polymerisation method.

EFFECT: producing a polyethylene-based moulding composition characterised by improved processability without formation of drops.

9 cl, 2 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a polyethylene film for making packaging, grocery sacks, trash can liners and produce bags. The film is made from a multimodal polymer composition obtained using a double metallocene catalyst and contains an ethylene homopolymer or a copolymer of ethylene and alpha-olefin comonomer or combination thereof and, optionally, additives and modifiers. The film is characterised by total energy dart drop, measured in accordance with ASTM D4272, greater than about 0.45 ft.lbf, dart drop impact strength, measured in accordance with ASTM D1709 Method A, greater than about 135 g, and moisture vapour transmission rate, measured in accordance with ASTM F1249 at 100°F and 90% relative humidity, less than about 0.85 g-mil/100 square inch/24 hour. Said tests are performed on a test specimen having a 0.8 mil thickness.

EFFECT: improved film properties.

20 cl, 2 dwg, 4 tbl, 4 ex

FIELD: chemistry.

SUBSTANCE: polymerisation method involves contacting propylene and optionally at least one other olefin with a catalyst composition in a first polymerisation reactor under gas-phase polymerisation conditions, the catalyst composition containing a procatalyst, a cocatalyst and a mixed external electron donor (M-EED) containing a first selectivity control agent (SCA1), a second selectivity control agent (SCA2), and an activity limiting agent (ALA); forming, in a first polymerisation reactor, an active propylene-based polymer having a melt flow rate greater than about 100 g/10 min as measured in accordance with ASTM D1238-01 (230°C, 2.16 kg); contacting the active propylene-based polymer with at least one olefin in a second reactor under polymerisation conditions; and obtaining an impact-resistant propylene copolymer having a melt flow rate greater than about 60 g/10 min. A version of the method and the polymer is disclosed.

EFFECT: obtaining an impact-resistant polymer with a high melt flow rate and low content of volatile substances.

10 cl, 4 tbl, 8 ex

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