Polyethylene moulding composition for pressure casting finished parts

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

 

The present invention relates to a polyethylene molding composition which has a multimodal molecular weight distribution and, in particular, suitable for the production of molded under pressure of finished parts, such as bottle caps and bottles, and the method of production of this molding composition in the presence of a suitable catalyst, preferably a catalyst of Ziegler.

The invention further relates to the use of such molding compositions for the production of molded under pressure of finished parts and finished parts that are manufactured by way of injection molding.

The terms "polyethylene molding composition which has a multimodal molecular weight distribution" or simply "a multimodal polyethylene" refers to a polyethylene molding composition or polyethylene, having a curve of molecular weight distribution with a multimodal configuration, i.e. polyethylene, containing many factions ethylene polymer having a single molecular weight. For example, according to preferred variants of implementation of the present invention, a multimodal polyethylene can be obtained by a multistage reaction sequence comprising successive stages of polymerization carried out in predetermined different re czynnik conditions in the respective reactors, connected in series, in order to obtain the appropriate fraction of polyethylene having different molecular weight. A process of this type can be performed in suspension medium: in this case, the monomers and the molecular weight regulator, preferably hydrogen, first polymerized in the first reactor in the first reaction conditions in the presence of a suspension medium and a suitable catalyst, preferably a Ziegler catalyst, then transferred to the second reactor and then polimerizuet second reaction conditions and, if the resulting polyethylene is, for example, tri-modal, then transferred to the third reactor and then polimerizuet in the third reaction conditions, and the first reaction conditions differ from the second and third reaction conditions, so that one obtains three fractions of polyethylene having different molecular mass. This difference in molecular masses in different fractions of the ethylene polymer is usually judged by srednevekovoi molecular mass Mw.

Although the Ziegler catalysts are particularly suitable for the preferred applications of the present invention, it is also possible to use other catalysts, for example catalysts with homogeneous catalytic center (or catalysts with "one heart"), for example metallocene catalysts.

The polyethylene is widely used in the manufacture of molded under pressure of finished parts. Polyethylene is used for this purpose should have a high mechanical strength and rigidity in order to be suitable for the production of thin-walled cast under pressure parts. In addition, the material must have a high degree of resistance to cracking under the action of the environment. If the finished parts are used as food packaging material must also have excellent organoleptic properties. In addition, for the above mentioned applications of molding the molding composition should be efficient, in particular in relation to injection molding.

Polyethylene molding composition having a unimodal molecular weight distribution, that is, one fraction containing ethylene polymer having a predetermined molecular weight, have shortcomings in terms of processability, resistance to cracking under the action of environmental and mechanical strength, which is undesirable for applications injection molding.

In comparison with this molding composition having a bimodal molecular weight distribution, represent a technological step forward. Molding the composition for molded under pressure of finished parts, based on polyethylene, which has a bimodal m is LeCoultre mass distribution, it's easy enough to handle, and it has better mechanical properties compared to conventional unimodal molding compositions. Although molding composition having a bimodal molecular weight distribution, easier to handle, and it has better resistance to cracking under the action of the environment and a higher mechanical strength at the same density with respect to unimodal molding compositions, mechanical properties, and in particular the resistance to cracking under the action of the environment, the strength and rigidity bimodal molding compositions, however, still require improvement.

Thus, the present invention is the creation of a molding composition based on polyethylene and which has significant benefits in terms of mechanical strength in conjunction with high rigidity and resistance to cracking under the action of the environment, while maintaining good workability, when subjected to the process of injection molding.

This problem is solved using a moulding composition having a multimodal molecular-phase distribution, containing from 25 to 50 wt.% ethylene homopolymer And low molecular weight, from 28 to 50 wt.% ethylene FOSS is the iMER In with high molecular weight and from 15 to 40 wt.% ethylene copolymer With ultra-high molecular weight, all percentages based on the total weight of the molding composition, where the molding composition has a density at 23°C in the range from 0,940 to 0,957 g/cm3, MFR (190°C/2,16 kg) in the range from 0.5 to 4 DG/min, and the coefficient of viscosity VN3a mixture of ethylene homopolymer And copolymer and the ethylene copolymer, measured in accordance with ISO/R 1191 in decaline at a temperature of 135°C in the range from 150 to 300 cm3/year

The expression "ethylene Homo-polymer And low molecular weight", "ethylene copolymer with high molecular weight and ethylene copolymer With ultra-high molecular weight" refers to the ethylene homopolymer And the ethylene copolymer and the ethylene copolymer C, respectively, which have different increasing molecular weight.

Thanks to this combination of characteristics and, in particular, through a multimodal molecular mass distribution, this special ranges MFR, coefficient of viscosity VN3and density, polyethylene moulding composition of the present invention can preferably be processed more easily, while having improved strength and rigidity.

Ethylene copolymer with high molecular weight and/or ethylene copolymer With ultra-high molecular weight are preferably sprinklers the action of ethylene, at least, additional olefin, which preferably has from 4 to 8 carbon atoms. Ethylene, thus, is used as the monomer, and used comonomer represents preferably 1-butene, 1-penten, 1-hexene, 1-octene, 4-methyl-1-penten or a combination of both. The preferred comonomers are 1-butene, 1-hexene and 4-methyl-1-penten. Particular preference is given to 1-butene.

The copolymer with high molecular weight preferably contains at least one comonomer in an amount of from 1 to 10 wt.%, more preferably from 1 to 8 wt.% and especially from 1 to 6 wt.%, based on the weight of copolymer Century

Copolymer With ultra-high molecular weight preferably contains at least one comonomer in an amount of from 1 to 10 wt.%, more preferably from 1 to 8 wt.% and especially from 1 to 6 wt.%, based on the weight of copolymer C.

These preferred amounts of comonomers make it possible to achieve improved resistance to cracking under the action of the environment. Within these preferred ranges polyethylene molding composition mainly has additionally improved combination of mechanical properties.

Ethylene copolymer With ultra-high molecular weight preferably contains one or more comonomers mentioned above in image quality is as example.

Polyethylene molding composition preferably has a density at 23°C in the range from 0,942 to 0,957 g/cm3more preferably in the range of from 0,945 to 0,957 g/cm3in particular in the range from 0,948 to 0,957 g/cm3.

Thus, the rigidity of the polyethylene molding composition additionally mainly increased without significant changes in other mechanical properties and processability.

Polyethylene molding composition preferably has a coefficient of viscosity VN3a mixture of ethylene homopolymer And the ethylene copolymer and the ethylene copolymer, measured in accordance with ISO/R 1191 in decaline at a temperature of 135°C in the range from 150 to 280 cm3/g, more preferably in the range of from 180 to 260 cm3/g, in particular in the range from 180 to 240 cm3/year

Polyethylene molding composition preferably has a flow index in the melt in accordance with ISO 1133, condition D, expressed as MFR (190°C/2,16 kg) in the range from 0.5 to 3 DG/min, more preferably from 0.7 to 3 DG/min, in particular from 1 to 2.7 DG/min

Polyethylene molding composition preferably get through a multistage reaction sequence comprising successive stages of polymerization. For example, when the reaction sequence is lnost has three stages, get a tri-modal polyethylene molding composition, while if the reaction sequence has four stages, get chetyrehbalnoy polyethylene molding composition.

In order to obtain a multimodal polyethylene, the polymerization can be conducted by a multi-stage process, i.e. the number of stages is carried out in the respective reactors connected in series, with the regulation of the molecular weight in each case by means of a molecular weight regulator, preferably hydrogen. In particular, the polymerization process is preferably carried out at a maximum concentration of hydrogen to be installed in the first reactor. In subsequent reactors, the hydrogen concentration is preferably gradually reduced so that the concentration of hydrogen used in the third reactor was small in relation to the concentration of hydrogen used in the second reactor. Preferably in the second reactor and the third reactor using a specific pre-concentration of co monomer, preferably increasing from the second reactor to the third reactor. As stated above, at the stages where they receive a fraction of the copolymer, preferably in the second reactor and the third reactor, ethylene, thus, used as a monomer, and olefin containing up to 8 carbon atoms, preferably used as co monomer.

Molecular weight distribution of the polyethylene moulding composition of the present invention is preferably a tri-modal. In this case, it is possible to obtain the above-mentioned preferential combination of properties without undue complication of the manufacturing process by providing three consecutive reactors, and, thus, predominantly containing the size of the plant. Thus, in order to obtain a tri-modal polyethylene molding composition, the polymerization of ethylene is preferably carried out in a continuous process performed in three reactors connected in series, in which three reactors set according to different reaction conditions. Preferably the polymerization is performed in suspension: a suitable catalyst such as a Ziegler catalyst, preferably fed to the first reactor together with the suspension medium, socialization, ethylene and hydrogen. Preferably the first reactor does not impose any co monomer. The suspension from the first reactor was then transferred to the second reactor, to which is added ethylene, hydrogen, and preferably also a pre-set amount of co monomer, such as 1-butene. The amount of hydrogen supplied to the second reactor, predpochtitel is however lower compared to the amount of hydrogen, fed into the first reactor. From the second reactor, the suspension is transferred into the third reactor. In the third reactor is injected ethylene, hydrogen, and preferably a pre-set amount of co monomer, such as 1-butene, preferably in quantities greater than the number of co monomer used in the second reactor. The amount of hydrogen in the second reactor is reduced compared to the amount of hydrogen in the second reactor. From the suspension of the polymer, leaving the third reactor, separating the suspension medium, and the resulting polymer powder is dried and then preferably granularit.

The polyethylene produced by polymerization of monomers, for example, in suspension, preferably at temperatures in the range from 70 to 90°C., preferably from 80 to 90°C at a preferred pressure in the range from 2 to 20 bar, preferably from 2 to 10 bar. The polymerization is preferably carried out in the presence of a suitable catalyst such as a Ziegler catalyst, preferably active enough to be certain predetermined performance multi-stage process. The Ziegler catalyst preferably comprises compounds of the transition metal and alyuminiiorganicheskikh connection.

Preferred trimodality, that is the preferred tri-modal curve molecular mass u is edeline, can be described in terms of the positions of the centers of gravity of three distinct molecular weight distributions by the viscosity VN in accordance with ISO/R 1191 for polymers obtained after each stage of polymerization.

Ethylene Homo-polymer And low molecular weight preferably is formed in the first stage of polymerization: in this preferred embodiment, the coefficient of viscosity VN1measured for the polymer obtained after the first stage polymerization, it is the coefficient of viscosity of the ethylene homopolymer And with low molecular weight and is preferably in the range from 50 to 150 cm3/g, more preferably from 60 to 120 cm3/g, in particular from 65 to 100 cm3/year

According to a possible alternative implementation of the first stage polymerization can be formed or ethylene copolymer with high molecular weight, or ethylene copolymer With ultra-high molecular weight.

Ethylene copolymer with high molecular weight preferably is formed in the second stage polymerization.

According to a particularly preferred variant implementation, in which the ethylene Homo-polymer And low molecular weight is formed in the first stage polymerization and ethylene copolymer with a high mole is Blarney mass is formed in the second stage polymerization, the coefficient of viscosity VN2measured for the polymer obtained after the second stage of polymerization, is a coefficient of viscosity of a mixture of ethylene homopolymer And with low molecular weight and ethylene copolymer with high molecular weight. VN2is preferably in the range from 70 to 180 cm3/g, more preferably from 90 to 170 cm3/g, in particular from 100 to 160 cm3/year

In this preferred embodiment, on the basis of these measured values VN1and VN2the coefficient of viscosity VNInethylene copolymer with high molecular weight can, for example, be calculated by the following empirical formula:

where w1is the mass fraction of ethylene homopolymer low molecular weight produced in the first stage of polymerization, as measured in wt.%, based on the total weight of polyethylene having a bimodal molecular weight distribution formed on the first two stages.

Ethylene copolymer With ultra-high molecular weight preferably is formed at the third stage of polymerization: in this preferred embodiment, as well as alternative options for implementation, providing a different order of polymerization, the ratio of wascott the VN 3measured for the polymer obtained after the third stage polymerization, it is the coefficient of viscosity of a mixture of ethylene homopolymer And low molecular weight, ethylene copolymer with high molecular weight and ethylene copolymer With ultra-high molecular weight. VN3is preferably within the preferred ranges already defined above, i.e. from 150 to 300 cm3/g, preferably from 150 to 280 cm3/g, more preferably from 180 to 260 cm3/g, in particular from 180 to 240 cm3/year

In this preferred embodiment, on the basis of these measured values VN2and VN3the coefficient of viscosity VNWithethylene copolymer With ultra-high molecular weight formed on the third stage polymerization can be, for example, be calculated by the following empirical formula:

where w2is the mass fraction of polyethylene having a bimodal molecular weight distribution formed on the first two stages, measured in wt.%, based on the total weight of polyethylene having a tri-modal molecular weight distribution formed in all three stages.

Although the method of calculating the viscosity of each fraction of the ethylene polymer is polyethylene is th molding composition is given with reference to the preferred case, in which the ethylene Homo-polymer And low molecular weight, ethylene copolymer with high molecular weight and, accordingly, the ethylene copolymer With ultra-high molecular weight receive in this manner, this method of calculation can also be applied to the polymerization carried out in other orders. In any case, virtually regardless of the order obtain three fractions of polyethylene coefficient of viscosity of the first fraction of the ethylene polymer is equal to the coefficient of viscosity VN1measured for ethylene polymer obtained after the first stage polymerization, the viscosity of the second fraction of the ethylene polymer can be derived from the mass fraction w1the first fraction of the ethylene polymer produced in the first stage of polymerization, as measured in wt.%, based on the total weight of polyethylene having a bimodal molecular weight distribution formed on the first two stages and from VN1and VN2measured for the polymers obtained after the second and respectively third stage of polymerization, while the coefficient of viscosity of a third faction, the ethylene polymer can be calculated based on the mass fraction w2polyethylene having a bimodal molecular weight distribution formed on the first two stages, measured in ve is.%, based on the total weight of polyethylene having a tri-modal molecular weight distribution formed on all three stages and from VN2and VN3measured for the polymers obtained after the second and respectively third stage polymerization.

Polyethylene molding composition according to the invention may further comprise additional optional additives. Such additives are, for example, stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, decontamination officers metals, compounds that destroy peroxide, total joint stabilizers in amounts of from 0 to 10 wt.%, preferably from 0 to 5 wt.%, as well as carbon black, fillers, pigments, antivalentine or combinations thereof in a total amount of from 0 to 50% wt.% on the basis of the total mass of the mixture.

Moulding composition according to the invention is predominantly possible to cast under pressure for the production of molded under pressure, preferably axisymmetric finished parts, such as bottle caps for cast under pressure plastic products or bottles.

Examples

Example 1 (invention)

Polymerization of ethylene was carried out in a continuous process in three reactors connected in series. The Ziegler catalyst, which was obtained by the method, opened in WO 91/18934, Example 2 under the nom operating the rum 2.2, filed in the first reactor in the amount of 14.3 mmol/h together with a sufficient quantity of hexane as the suspension medium, triethylaluminium as socializaton in the amount of 180 mmol/h, ethylene and hydrogen. The number of ethylene (=51,7 kg/h) and the amount of hydrogen (=62 g/h) was set so that in the gas space of the first reactor was determined share of 24% vol. ethylene and 68% vol. hydrogen; the remainder was a mixture of nitrogen and transferred into the vapor state of the suspension medium. The polymerization in the first reactor was carried out at a temperature of 84°C. the Suspension from the first reactor was then applied to the second reactor, in which the proportion of hydrogen in the gas space was lowered to 55 vol.% and who was introduced ethylene in the amount of 54.5 kg/h and 1-butene in the amount of 450 g/h added as substances dissolved in the recirculating suspension environment. Reduce the amount of hydrogen was achieved by means of an intermediate pressure relief H2. In the gas space of the second reactor was determined 40% vol. ethylene, 55% vol. hydrogen and 0.4 vol.% 1-butene, the remainder was a mixture of nitrogen and transferred into the vapor state of the suspension medium. The polymerization in the second reactor was carried out at a temperature of 85°C. the Slurry from the second reactor was then transferred to the third reactor by means of additional intermediate reset the sa pressure H 2whereby the amount of hydrogen in the gas space of the third reactor was set equal to 2.1%. In the third reactor was introduced ethylene in the amount of 38.3 kg/h and 1-butene in the number of 3900 g/h of the gas space of the third reactor was determined 79% ethylene, 2,1 vol.% hydrogen and 11% vol. 1-butene, the remainder was a mixture of nitrogen and transferred into the vapor state of the suspension medium. The polymerization in the second reactor was carried out at a temperature of 85°C. From the suspension of the polymer, leaving the third reactor, separating the suspension medium, and the resulting polymer powder was dried and granulated.

Bottle caps with a diameter of 40 mm and a wall thickness of 2 mm was molded under pressure at the molding temperature of 210°C and confining pressure of 750 bar on the machine for casting under pressure of 250 KM Krauss Maffei (with a maximum clamping force 2750 kN and the diameter of the bolt 50 mm)using 4-cavitary device with the bolt. The surface temperature of the devices was 30°C. the resulting bottle caps had a defect-free surface.

The coefficients of viscosity and share WA, WB, WCpolymers a, b and C for polyethylene moulding composition obtained as described in example 1 shown in table 1 below.

the table 1
Example 1
WA[wt.%]36
WB[wt.%]38
WC[wt.%]26
VN1[cm3/g]76
VN2[cm3/g]130
VN3[cm3/g]230
Density [g/cm3]0,954
MFR (190°C/2,16 kg) [DG/min]1,5
ESCR [h]50
ACN (-23°C) [kJ/m2]5,5
The length of the spiral [mm]175

Abbreviations in table 1 have the following meanings:

- WA, WB, WC= mass [%] of the ethylene homopolymer And low molecular weight, ethylene copolymer with high molecular weight and ethylene copolymer With ultra-high molecular weight, respectively;

- VN1, VN2and VN3= coefficient Vascos is in [cm 3/g] ethylene homopolymer And a mixture of polymer a and polymer b and a mixture of ethylene homopolymer And copolymer and the ethylene copolymer C, respectively, measured in accordance with ISO/R 1191 in decaline at a temperature of 135°C;

is the density measured at 23°C in accordance with ISO 1183 in [g/cm3];

- MFR(190°C/2,16 kg) = flow index in the melt in accordance with ISO 1133, condition D in [DG/min];

- ESCR = resistance to cracking under the action of the environment, measured by the method of M. Fleβner (test sample with a wide notch creep) in [h] under the conditions of 80°C, 2.5 MPa, water/2% Arkopal. This laboratory method is described M. Fleiβner in Kunstsoffe 77 (1987), c. 45 et seq., and complies with ISO/CD 16770. This publication shows that there is a correlation between the growth trend of resistance to cracking in the creep testing on test bars having a peripheral notch, and the area of brittle fracture in trials on long-term internal pressure in accordance with ISO 1167. Reduce the time required for damage, reach by shortening the time of initiation of cracking through cuts (with a depth of cut of 1.6 mm/razor blade) in aqueous solution Arkopal with fortress 2% as the environment, promoting the formation of cracks under tension, at a temperature of 80°C and a tensile stress of 2.5 MP is. Samples were made by sawing off the three test specimens having dimensions of 10×10×90 mm from the extruded sheet with a thickness of 10 mm. of test Specimens cut in the middle of a circle with a razor blade on a makeshift cutting machine (see Figure 5 in publication);

- ASN = impact strength notched specimen, measured according to ISO 179-1/1eA/DIN 53453 in [kJ/m2] at 23°C;

- the length of the spiral = length of the spiral in [mm], which is obtained in the tests on fluidity, where the spiral is moulded under pressure from the polymer. As is known from applications of injection molding, the resulting length of the helix, manufactured with injection molding, is a measure of the technological properties during injection molding. Here are the figures based on the temperature input 190°C. and the pressure input 1050 bar and the wall thickness of spirals 1 mm.

Example 2 (comparative example)

Polymerization of ethylene was carried out in a continuous process in two reactors connected in series. The Ziegler catalyst, which was obtained by the method, opened in WO 91/18934, Example 2 under operating room 2.2, was filed in the first reactor in the amount of 14.3 mmol/h together with a sufficient amount of the suspension medium, triethylaluminium as socializaton in the amount of 180 mmol/h, ethylene and hydrogen. The number of ethylene(=71.5 kg/h) and the amount of hydrogen (=79 g/h) was set so that so in the gas space of the first reactor was determined share of 26% vol. ethylene and share 61% of hydrogen. In addition, it was determined the share of 1.2% vol. 1-butene, which was administered as a 1-butene dissolved in recirculating suspension medium; the remainder was a mixture of nitrogen and transferred into the vapor state of the suspension medium. The polymerization in the first reactor was carried out at a temperature of 84°C. the Suspension from the first reactor was then transferred to the second reactor, in which the proportion of hydrogen in the gas space was reduced to 19% vol. and who was administered the ethylene in the number of 58.5 kg/h and 1-butene in the number 2350 l/h reduce the amount of hydrogen was achieved by means of an intermediate pressure relief H2. In the gas space of the second reactor was determined by 67% ethylene, 19% vol. hydrogen and 6.5% vol. 1-butene, the remainder was a mixture of nitrogen and transferred into the vapor state of the suspension medium. The polymerization in the second reactor was carried out at a temperature of 85°C. a Suspension of the polymer, leaving the second reactor, was sent granulation after separating the suspension medium and dried powder.

Bottle caps with a diameter of 40 mm and a wall thickness of 2 mm was molded under pressure at the molding temperature of 210°C and confining pressure of 750 bar on the machine for casting under pressure of 250 KM Krauss Maffei (if the maximum is s clamping 2750 kN and the diameter of the bolt 50 mm), using 4-cavitary device with the bolt. The surface temperature of the devices was 30°C. the resulting bottle caps had a defect-free surface.

The coefficients of viscosity and share WA, WBand WCpolymers a, b and C for polyethylene moulding composition obtained as described in comparative example 2 shown in table 2 below.

Table 2
Example 2 (comparative example)
WA[wt.%]55
WB[wt.%]45
VN1[cm3/g]53
VN2[cm3/g]160
Density [g/cm3]0,951
MFR (190°C/2,16 kg) [DG/min]1,0
ESCR [h]12
ACN (-23°C) [kJ/m2]the 4.7
The length of the spiral [mm]145

1. The polyethylene is new molding composition for injection molding, which has a multimodal molecular weight distribution and contains from 25 to 50 wt.% ethylene homopolymer And low molecular weight, from 28 to 50 wt.% ethylene copolymer with high molecular weight and from 15 to 40 wt.% ethylene copolymer With ultra-high molecular weight, all percentages based on the total weight of the molding composition and the ethylene homopolymer And ethylene copolymer and the ethylene copolymer To have a different molecular weight, and has a density at 23°C in the range from 0,948 to 0,957 g/cm3the melt flow index MFR, measured in accordance with ISO 1133, condition D (190°C/2,16 kg)in the range from 1 to 2.7 DG/min, and the coefficient of viscosity VN3a mixture of ethylene homopolymer And copolymer and the ethylene copolymer, measured in accordance with ISO/R 1191 in decaline at a temperature of 135°C, in the range from 150 to 240 cm3/g, and where the polyethylene molding composition is produced by a multistage reaction sequence comprising successive stages of polymerization, and where the coefficient of viscosity VN1measured for ethylene homopolymer And low molecular weight after the first stage polymerization is in the range from 65 to 100 cm3/g, and the coefficient of viscosity VN2measured for a mixture of ethylene homopolymer the low molecular weight plus ethylene copolymer with high molecular weight after the second stage of polymerization, is in the range from 100 to 160 cm3/year

2. Polyethylene molding composition according to claim 1, in which the ethylene copolymer with high molecular weight and ethylene copolymer With ultra-high molecular weight are copolymers of ethylene and at least additional olefin having from 4 to 8 carbon atoms.

3. Polyethylene molding composition according to claim 2, in which the olefin include 1-butene, 1-penten, 1-hexene, 1-octene, 4-methyl-1-penten or a combination of both.

4. Polyethylene molding composition according to claim 1 in which the copolymer with high molecular weight contains at least one comonomer in an amount of from 1 to 6 wt.%, based on the weight of copolymer Century

5. Polyethylene molding composition according to claim 1 in which the copolymer With ultra-high molecular weight contains at least one comonomer in an amount of from 1 to 6 wt.%, based on the weight of copolymer C.

6. A method of obtaining a polyethylene molding composition according to one or more of claims 1 to 5, in which three-stage polymerization of the monomers is carried out in suspension at temperatures in the range from 70 to 90°C., a pressure of from 2 to 10 bar and in the presence of Ziegler catalyst, which consists of compounds of the transition metal and alyuminiiorganicheskikh connection with the molecular weight of the polyethylene, resulting in each of the stages, regulated in each case by means of hydrogen.

7. The use of the moulding compositions according to one or more of claims 1 to 5 for the production of molded under pressure of finished parts.

8. The finished part produced by injection molding, with the polyethylene molding composition according to one or more of claims 1 to 5.



 

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22 cl, 1 tbl, 16 ex

FIELD: chemistry.

SUBSTANCE: resin has melt index MI5 from 0.40 to 0.70 g/10 min and contains from 47 to 52 wt % low-molecular polyethylene fraction and from 48 to 53 wt % high-molecular polyethylene fraction, where the high-molecular polyethylene fraction includes a copolymer of ethylene and 1-hexene and 1-octene.

EFFECT: improved hydrostatic properties.

5 cl, 3 tbl, 6 ex

FIELD: chemistry.

SUBSTANCE: invention relates to polyethylene mixed compositions, intended for film manufacturing, which include two or more different ethylene polymers, each of which has different degree of complexity of long chain branching. Polyethylene composition is practically linear and has average index of branching constituting 0.85 or less. In addition, composition has density 0.935 g/cm3 or less, dullness - 10% or less and stability to falling load impact - 100g/mm or more, determined according to ASTM D-1709 methodology.

EFFECT: polyethylene compositions possess definite combination of required properties and characteristics, good optic properties and strengthening characteristics.

15 cl, 1 dwg, 5 tbl, 5 ex

FIELD: chemistry.

SUBSTANCE: invention refers to making a moulded product for handling clean-room materials, intermediate products or end products, such as a container, a tray and a tool. The moulded product is made of resin compound prepared by mixing in melt cycloolefine polymer (A) 100 weight fractions chosen from the group including bicyclo[2.2.1]-2-heptene and its derivatives, tricyclo [4,3,0,12,5]-3-decene and its derivatives, and tetracyclo[4,4,0,12,5,17,10]-3-dodecene and its derivatives of vitrification temperature within 60 to 200°C, and amorphous or low-crystalline elastic copolymer (B(b1)) 1 to 150 weight fractions. Copolymer (B(b1)) is polymerised from at least two monomers chosen from the group including ethylene and a-olefin with 3 to 20 carbon atoms and vitrification temperature 0°C or lower. The compound contains radical polymerisation initiator 0.001 to 1 weight fractions containing peroxide, and polyfunctional compound (D) 0 to 1 weight fractions. The compound (D) has at least two radical-polymerised functional groups chosen from the group including vinyl group, allylic group, acrylic group and methacrylic group in a molecule.

EFFECT: clean-room moulded product is characterised with good chemical stability, heat resistance and dimensional accuracy, it prevents volatile component release in the surrounding space, has good abrasion resistance and prevents particle formation.

19 cl, 1 tbl, 2 dwg, 12 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: composition contains a mixture of a low molecular weight polyethylene component and a high molecular weight polyethylene component and a binding agent containing at least 0.0025 wt % polysulphonyl azide. The mixture has sine peak on the lamella thickness distribution (LTD) curve.

EFFECT: prolonged wear resistance of pipes under gas or water pressure, resistance to cracking under stress associated with environmental factors, resistance to slow formation of cracks, to fast crack propagation and to creep under internal stress.

64 cl, 3 dwg, 24 tbl, 6 ex

FIELD: chemistry.

SUBSTANCE: film is made from a composition having multi-modal molecular-weight distribution and density between 0.940 and 0.948 g/cm3. The composition contains 40-60 wt % of a first fraction of an ethylene polymer made from a homopolymer A, 25-45 wt % of a second fraction of ethylene polymer made from a first copolymer B of ethylene and at least one first comonomer from a group of olefins having 4-8 carbon atoms and 10-30 wt % of a third fraction of ethylene polymer made from a second copolymer C of ethylene and at least one second comonomer from a group of olefins having 4-8 carbon atoms. The first copolymer B of ethylene has molecular weight which is less than that of the second copolymer C of ethylene, but greater than that of homopolymer A.

EFFECT: disclosed thin films have improved mechanical properties, particularly impact resistance when testing the films using a falling pointed load, with high rate of collection without deterioration of stability of the molten bubble.

12 cl, 2 tbl, 3 ex

FIELD: chemistry.

SUBSTANCE: invention relates to a polyethylene moulding composition having multi-modal molecular-weight distribution, especially suitable for films made via extrusion blowing, having thickness between 8 and 200 mcm. The polyethylene moulding composition has density between 0.953 and 0.960 g/cm3 and MFR190/5 of the end product after extrusion between 0.10 and 0.50 dg/min. The composition contains 42-52 wt % of a first fraction of ethylene polymer made from a homopolymer A, having a first molecular weight, 27-38 wt % of a second fraction of ethylene polymer made from another homopolymer or a first copolymer B of ethylene and at least one first comonomer from a group of olefins having 4-8 carbon atoms,whereby the first copolymer B has a second molecular weight greater than the said first molecular weight, and 15-25 wt % of a third fraction of ethylene polymer made from a second copolymer C having a third molecular weight greater than the second molecular weight.

EFFECT: disclosed polyethylene moulding composition enables to obtain thin films with improve processing properties without deterioration of mechanical properties.

12 cl, 2 tbl, 3 ex

Polyethylene tubes // 2394052

FIELD: chemistry.

SUBSTANCE: method involves preparation of a mixture containing 5-50 wt % filler and 95-50 wt % low density polyethylene and 0-3 wt % of one or more stabilisers.The obtained mixture and high density polyethylene containing at least one low-molecular component which is a copolymer of ethylene and C3-C10 α-olefin are mixed in a molten mass until the end product is obtained at drop point of 165-185°C. The obtained composition for making tubes contains 1-20 wt % filler in terms of mass of the composition.

EFFECT: composition has better balance of properties and can be extruded with sufficiently high efficiency at optimal low melt temperature.

19 cl, 3 tbl, 7 ex

FIELD: chemistry.

SUBSTANCE: present invention relates to a polyethylene composition with multimodal molecular weight distribution for blow moulding canisters with volume ranging from 2 to 20 dm3 and a method of preparing the said composition. The composition has density ranging from 0.950 to 0.958 g/cm3 at 23°C and melt flow rate (MFR190/5) from 0.30 to 0.50 dg/min. The composition also contains 40 to 50 wt % low molecular weight ethylene homopolymer A and 25 to less than 30 wt % high molecular weight copolymer B obtained from ethylene and another 1-olefin containing 4 to 8 carbon atoms, and 24 to 28 wt % ethylene copolymer C having ultra-high molecular weight.

EFFECT: obtained composition has good resistance to chemical effect, especially high mechanical strength, high corrosion resistance and is a naturally light material; high melt strength of the composition enables prolonged extrusion without breaking the workpiece, and an accurately selected swelling index of the composition enables optimisation of controlling thickness of the wall of the article.

10 cl, 1 tbl, 1 ex

FIELD: chemistry.

SUBSTANCE: polyethylene in form of ethylene homopolymers and copolymers of ethylene with α-olefins and having molecular weight distribution range Mw/Mn from 6 to 100, density from 0.89 to 0.97 g/cm3, weight-average molecular weight Mw from 5000 g/mol to 700000 g/mol and from 0.01 to 20 branches/1000 carbon atoms and at least 0.5 vinyl groups/1000 carbon atoms, where the fraction of polyethylene with molecular weight less than 10000 g/mol has degree of branching from 0 to 1.5 branches on the side chains, longer than CH3/1000 carbon atoms. The catalyst composition for synthesis of polyethylene in paragraph 1 consists of at least two different polymerisation catalysts, from which A) is at least one polymerisation catalyst based on monocyclopentadienyl complex of a group IV-VI metal, in which the cyclopentadienyl system is substituted by an uncharged donor (A1) of formula Cp-Zk-A-MA (II), where variables assume the following values: Cp-Zk-A is , MA is a metal which is selected from a group consisting of titanium (III), vanadium, chromium, molybdenum and tungsten, and k equals 0 or 1, or with hafnocene (A2), and B) is at least one polymerisation catalyst based on a ferrous component with a tridentate ligand containing at least two ortho-, ortho-disubstituted aryl radicals (B).

EFFECT: obtaining polyethylene with good mechanical properties, possibility for processing and high content of vinyl groups.

27 cl, 12 ex, 2 tbl, 5 dwg

FIELD: chemistry.

SUBSTANCE: invention relates to high-strength bimodal polyethylene compositions which are meant for preparing compositions for pipes, particularly high-strength compositions for pipes. The composition has density equal to or greater than 0.940 g/cm3, overall polydispersity index equal to or greater than 25 and contains a high-molecular polyethylene component and a low-molecular polyethylene component. The ratio of weight-average molecular weight of the high-molecular component to the weight-average molecular weight of the low-molecular component of the composition is equal to or greater than 30. The weight-average molecular weight of the low-molecular polyethylene component ranges from 5000 to 30000. The composition is classified as PE 100 material, has proper balance of properties such as strength and hardness, as well as good processing properties. A pipe made from the composition which has undergone internal strength tests has extrapolated stress equal to or greater than 10 MPa when the internal strength curve of the pipe is extrapolated to 50 or 100 years in accordance with ISO 9080:2003(E).

EFFECT: increased strength of products.

15 cl, 6 tbl, 10 ex

FIELD: chemistry.

SUBSTANCE: present invention relates to a method of preparing an ethylene polymer composition. Described is a method of preparing an ethylene polymer composition in a multistage process. The said method involves polymerisation of only one of ethylene or ethylene with a comonomer to obtain ethylene polymer at the first stage, supply of the polymer obtained at the first stage to the second stage, where at the second stage only one of ethylene or ethylene with a comonomer is polymerised in the presence of the polymer obtained at the first stage, and where the first stage is a suspension polymerisation stage, and polymerisation at the first stage is carried out in the presence of a catalyst system containing: (a) a precursor solid catalyst containing a transition metal selected from titanium and vanadium; magnesium, haloid, electron donor and solid dispersion material containing inorganic oxide, and (b) organoaluminium compound; and where the average diametre of particles of the precursor solid catalyst obtained per total volume of the precursor solid catalyst, D50, ranges from 1 to 13 micrometres. Also described is an ethylene polymer composition obtained using the said method, having density in the range 0.915-0.970 g/cm3 and MI5 in the range 0.02-3.5 dg/min and less than 6 regions of gel per m2 with size greater than 800 micrometres, and less than 100 regions of gel per m2 with size ranging from 400 to 800 micrometres, where the amount and size of gel is determined for a 5 m2 cast film sample with thickness of 50 micrometres, obtained from the ethylene polymer composition; also described is an industrial product made from the said composition. Described is an ethylene polymer composition obtained using the said method, having density in the range 0.915-0.970 g/cm3 and MI5 in the range 0.02-3.5 dg/min, where the composition has Young's modulus during bending, measured using an Instron device in accordance with ISO 178, exceeding 1340*{1-exp[-235*(density-0.9451)]}; ethylene polymer composition having density in the range 0.915-0.970 g/cm3 and MI5 in the range 0.02-3.5 dg/min, where the composition has Young's modulus during bending which exceeds 1355*{1-exp[-235*(density-0.9448)]}. Described is a composition obtained using the said method and containing bimodal polyethylene resin, and where the bimodal polyethylene resin contains high-molecular ethylene polymer and low-molecular ethylene polymer, and where the low-molecular ethylene polymer has MI2 ranging from 10 g/10 min to 1000 g/10 min and density of at least 0.920 g/cm3, and where the composition has density ranging from 0.915 g/cm3 to 0.970 g/cm3.

EFFECT: improved mechanical properties of products made from the compositions, reduced amount of gel in the compositions.

20 cl, 38 ex, 1 dwg, 4 tbl

FIELD: chemistry.

SUBSTANCE: thermoplastic elastomer material contains: (a) from 10 to 100 wt % of at least one thermoplastic elastomer based on styrene; (b) from 0 to 90 wt % of at least one thermoplastic homopolymer or copolymer of α-olefin, different from (a); where amount of (a)+(b) equals 100; (c) from 2 to 90 pts. wt of vulcanised rubber in crushed state; (d) from 0.01 to 10 pts. wt of at least one coupling agent which contains at least one unsaturated ethylene; where amounts (c) and (d) are expressed in ratio to 100 pts. wt of (a)+(b).

EFFECT: improved mechanical properties, specifically breaking stress and breaking elongation, increased wear resistance.

60 cl, 6 tbl, 6 ex

FIELD: chemistry.

SUBSTANCE: invention relates to making articles with an elongated shape with a regular microrelief on the surface, which can be used as elements of optoelectronic devices and information display systems. In the first version, articles with an elongated shape made from glass-like non-oriented or partially oriented polymer are treated with low-temperature plasma. The articles are then heated to temperature higher than the glass transition point (Tg). The articles are stretched in at least one direction. The articles are cooled to temperature lower than Tg of the polymer while fixing the size of the article in the direction of stretching. In the second version, the non-oriented or partially oriented article made from amorphous glass-like or polycrystalline polymer is treated with low-temperature plasma. The article is stretched at temperature lower than Tg for the amorphous polymer and lower than melting point (Tm) for the polycrystalline polymer. In the third version, an article in high-elastic state of the polymer is treated with low-temperature plasma. The article is stretched while fixing the size of the stretched article in the direction of stretching. In the fourth version, an article made from amorphous or polycrystalline polymer is used. The article is stretched at temperature higher than Tg for the amorphous polymer and lower than Tm for the polycrystalline polymer. The article is treated with low-temperature plasma while fixing the size of the article with subsequent removal of the fixing.

EFFECT: easier formation of a regular microrelief on the surface of polymer articles.

8 cl, 7 dwg, 4 ex

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