JP5168779B2 - Ethylene polymer - Google Patents

Description

  The present invention relates to an ethylene polymer having a high melt tension. More specifically, the present invention relates to an ethylene polymer having a high melt tension that is excellent in thermal stability and excellent in moldability.

Low density polyethylene (LDPE) produced by the high pressure radical method is an ethylene polymer having a high melt tension (MS). However, since the flow activation energy (E _a ) is large and the temperature dependence of the melt viscosity is large, it has a high MS only in a specific molding processing temperature range, and is suitable for a polymer to be processed in the molding processing. It was necessary to select a machine.

The ethylene-based polymer obtained by Ziegler catalysts or metallocene catalysts, although E _a is small, MS is a problem in moldability lowered.

Examples of the ethylene-based polymer with improved moldability include (a) an ethylene-α-olefin copolymer having a long chain branch obtained under specific polymerization conditions using a specific metallocene catalyst (for example, a patent) references 1), (b) it was obtained in a specific metallocene catalyst, ethylene -α- olefin copolymer (for example, refer to Patent Document 2) are proposed _{E a} is 60 kJ / mol or more. However, these ethylene copolymers, like LDPE, have a large Ea and _a large temperature dependence of melt viscosity, and therefore it was necessary to strictly control the temperature in the molding process.

In order to have stable processability in a wide range of molding temperatures, an ethylene polymer having _a low Ea and _a high MS is preferable. As such a polymer, there is an ethylene polymer produced by using a Cr-based catalyst. In our study, the number of terminal vinyl groups per 1,000 carbon atoms in the ethylene polymer is 0.3. Because of the above, there was a problem in thermal stability such as yellowing during melt processing. Thus, the number of unsaturated bonds such as terminal vinyl groups is superior in less thermal stability, ethylene polymer E _a has excellent moldability in a wide molding processing temperature range lower has been desired.

US Pat. No. 5,272,236 Japanese Patent Laid-Open No. 2004-292772

The present invention has been made in order to solve the problems of the prior art as described above, and is an ethylene polymer having _a low number of terminal vinyl groups and excellent thermal stability, _a low Ea, and _a high MS. It is to provide.

The present invention has been found as a result of intensive studies on the above-described object. That is, the present invention comprises a repeating unit derived from ethylene, or a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms, and satisfies the following (A) to (F). The present invention relates to an ethylene polymer.
(A) The density [d (kg / m ³ )] is 910 or more and 970 or less,
(B) The melt flow rate [MFR (g / 10 min)] measured at 190 ° C. and a load of 2.16 kg is 0.01 to 50,
(C) the number of terminal vinyls is 0.2 or less per 1,000 carbon atoms,
(D) The melt tension [MS ₁₆₀ (mN)] and MFR measured at 160 ° C. satisfy the following formula (1),
MS ₁₆₀ > 90-130 × log (MFR) (1)
(E) Melt tension [MS ₁₉₀ (mN)] measured at 190 ° C. and MS ₁₆₀ satisfy the following formula (2):
MS ₁₆₀ / MS ₁₉₀ <1.8 (2)
(F) Flow activation energy [E _a (kJ / mol)] and d satisfy the following formula (3).

_{127-0.107d <E a <88-0.060d (3} )

  The ethylene-based polymer of the present invention is an ethylene polymer comprising a repeating unit derived from ethylene, or an ethylene-α-olefin comprising a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms. It is a copolymer.

  The repeating unit derived from ethylene is a unit derived from ethylene as a monomer and contained in an ethylene polymer or an ethylene-α-olefin copolymer. The repeating unit derived from an α-olefin having 3 to 8 carbon atoms is a unit derived from an α-olefin having 3 to 8 carbon atoms as a monomer and contained in an ethylene-α-olefin copolymer. . Examples of the α-olefin having 3 to 8 carbon atoms include propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, and 3-methyl-1-butene. You may use together at least 2 types of these C3-C8 alpha olefins.

The (A) density [d (kg / m ³ )] of the ethylene-based polymer of the present invention is a value measured by a density gradient tube method in accordance with JIS K6760 (1995), and is 910 kg / m ³ or more and 970 kg / m ³ or less, preferably 910 kg / m ³ or more and 940 kg / m ³ or less. When the density is less than 910, the melting temperature of the product is low and only a product having poor heat resistance can be obtained. On the other hand, if it exceeds 970, the product is excellent in heat resistance and rigidity, but the impact strength is lowered.

The number of vinyl terminals (C) in the ethylene polymer of the present invention is determined by using a Fourier transform infrared spectrophotometer (FT-IR) to heat-press the ethylene polymer and then cooling it with ice. measured in the range of 4000cm ^-1 ~400cm ^-1, it was calculated using the following equation.

Number of terminal vinyls per 1000 carbon atoms (pieces / 1000 C) = a × A / L / d
In the formula, a represents an absorptivity coefficient, A represents an absorbance of 909 cm ⁻¹ attributed to terminal vinyl, L represents a film thickness, and d represents a density. In addition, a was calculated | required from the analytical curve created using the sample which confirmed the number of terminal vinyls per 1000 carbon atoms from < ¹ > H-NMR measurement. ¹ H-NMR measurement was performed at 130 ° C. in a mixed solvent of deuterated benzene and o-dichlorobenzene using GSX400 manufactured by JEOL. The number of terminal vinyls per 1000 carbon atoms was calculated from the integral ratio of the peak attributed to methylene and the peak attributed to terminal vinyl. With respect to each peak, tetramethylsilane was used as a standard (0 ppm), and a peak with a chemical shift of 1.3 ppm was attributed to methylene and a peak with 4.8 to 5.0 ppm was assigned to terminal vinyl. The number of (C) terminal vinyls in the ethylene polymer of the present invention is 0.2 or less per 1,000 carbon atoms, preferably 0.1 or less. When the number of terminal vinyls exceeds 0.2 per 1,000 carbon atoms, the problem of thermal deterioration during molding, particularly yellowing, occurs.

The melt tension [MS ₁₆₀ (mN)] of the ethylene-based polymer of the present invention uses a die having a length of 8 mm and a diameter of 2.095 mm, an inflow angle of 90 °, a shear rate of 10.8 s ⁻¹ , and stretching. Although it is a value measured at a measurement temperature of 160 ° C. under a condition of a ratio of 47, when the maximum stretch ratio is less than 47, the value measured at the highest stretch ratio that does not break was designated as MS ₁₆₀ . The melt tension measured by the same method with the temperature set at 190 ° C. was defined as MS ₁₉₀ (mN).

  The (B) melt flow rate [MFR (g / 10 min)] of the ethylene-based polymer of the present invention is a value measured at 190 ° C. under a 2.16 kg load, and is from 0.01 to 50. An MFR of less than 0.01 is not preferable because the load on the extruder increases during the molding process and the production decreases. On the other hand, if it exceeds 50, the melt tension becomes small, and the strength of the product also decreases, which is not preferable.

(D) MS ₁₆₀ and MFR of the ethylene polymer of the present invention are represented by the following formula (1).
MS ₁₆₀ > 90-130 × log (MFR) (1)
And preferably the following formula (4)
MS ₁₆₀ > 110-130 × log (MFR) (4)
There is a relationship that satisfies.

When MS ₁₆₀ is in the range of [90-130 × log (MFR)] or less, a problem occurs in moldability.

(E) MS ₁₉₀ and MS ₁₆₀ of the ethylene polymer of the present invention are represented by the following formula (5).
MS ₁₆₀ / MS ₁₉₀ <1.8 (2)
And preferably the following formula (19)
MS ₁₆₀ / MS ₁₉₀ <1.7 (5)
There is a relationship that satisfies.

When MS ₁₆₀ / MS ₁₉₀ is in the range of 1.8 or more, the melt tension varies greatly depending on the temperature, so that it is necessary to strictly adjust the molding temperature, and the molding range is narrowed.

The activation energy [E _a (kJ / mol)] of (F) flow of the ethylene-based polymer of the present invention is obtained by substituting the shift factor obtained by dynamic viscoelasticity measurement at 160 ° C. to 230 ° C. into the Arrhenius equation. The calculated value, the following formula (2)
_{127-0.107d <E a <88-0.060d (3} )
And preferably the following formula (6)
_{127-0.107d <E a <87-0.060d (6} )
Meet.

When E _a is in the (127-0.107d) the range, problems in workability. Also, when the range E _a is (88-0.060d) or more, the temperature dependency of the melt viscosity increases, tight regulation of the molding temperature is required, the molding range is narrow and thus.

The ratio (M _w / M _n ) of weight average molecular weight (M _w ) and number average molecular weight (M _n ) measured by (G) gel permeation chromatography (GPC) of the ethylene polymer of the present invention is Preferably they are 2 or more and 6 or less, More preferably, they are 2 or more and 5 or less. When _Mw / _Mn is decreased, the mechanical strength of the molded product is improved.

  The ethylene polymer of the present invention satisfying the above requirements (A) to (F), preferably satisfying the above requirement (G), can be arbitrarily selected according to the production conditions themselves of the examples of the present invention to be described later or minor fluctuations of the condition factors. It is possible to make them separately. Specific examples of condition factor fluctuations include: requirements for catalyst components such as the structure of components (a) and (b) used, the amount of component (b) relative to component (a), the type of promoter component used, and the polymerization temperature It can also be made by controlling polymerization conditions such as ethylene partial pressure, the amount of a molecular weight adjusting agent such as hydrogen to be coexisted, and the amount of comonomer added. Furthermore, the range of physical properties can be expanded by combining with multi-stage polymerization.

More specifically, it is possible to reduce the number of terminal vinyls by, for example, reducing the ethylene partial pressure, reducing the amount of comonomer addition, or changing the structure of component (a). Also, the melt tension can change the structure of component (a), increase the number of terminal vinyls, change the structure of component (b), reduce ethylene partial pressure, increase the number of long-chain branches. It can be increased by increasing the long chain branching length, changing the amount of component (b) relative to component (a), increasing Mw / Mn, and the like. Furthermore, the flow activation energy (E _a ) is determined based on the structure of the component (a), the number of terminal vinyls, the structure of the component (b), the ethylene partial pressure, the number of long chain branches, the long chain branch length, and the component (a). Control is possible by the amount of component (b).

  As the method for producing an ethylene polymer of the present invention, for example, as a metallocene compound, two cyclopentadienyl groups are cross-linked by a cross-linking group composed of a chain of two or more atoms, or two or more atoms of Cross-linked biscyclopentadienyl zirconium complex [component (a)] cross-linked with a cross-linking group consisting of a chain, cross-linked (cyclopentadienyl) (fluorenyl) zirconium complex and / or cross-linked (indenyl) (fluorenyl) ) A method of polymerizing ethylene or copolymerizing ethylene and an α-olefin having 3 to 8 carbon atoms in the presence of a metallocene catalyst using a zirconium complex [component (b)] can be used.

  Specific examples of component (a) include 1,1,3,3-tetramethyldisiloxane-1,3-diyl-bis (cyclopentadienyl) zirconium dichloride, 1,1-dimethyl-1-silaethane-1. , 2-diyl-bis (cyclopentadienyl) zirconium dichloride, propane-1,3-diyl-bis (cyclopentadienyl) zirconium dichloride, butane-1,4-diyl-bis (cyclopentadienyl) zirconium dichloride Cis-2-butene-1,4-diyl-bis (cyclopentadienyl) zirconium dichloride, 1,1,2,2-tetramethyldisilane-1,2-diyl-bis (cyclopentadienyl) zirconium dichloride And the above transition metal compounds such as dimethyl, diethyl, dihy B body, diphenyl body, can be exemplified dibenzyl body.

  Specific examples of component (b) include diphenylmethylene (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (2-trimethylsilyl-1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, Diphenylmethylene (1-cyclopentadienyl) (2,7-dimethyl-9-fluorenyl) zirconium dichloride, diphenylmethylene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium Dichloride, isopropylidene (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, isopropylidene (1-cyclopentadienyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, diphenylsila Diyl (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, dimethylsilanediyl (1-cyclopentadienyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (1-indenyl) (9-fluorenyl) zirconium dichloride Diphenylmethylene (2-phenyl-1-indenyl) (9-fluorenyl) zirconium dichloride, diphenylmethylene (2-phenyl-1-indenyl) (2,7-di-t-butyl-9-fluorenyl) zirconium dichloride, etc. Examples thereof include dimethyl, diethyl, dihydro, diphenyl, and dibenzyl isomers of dichloride and the above transition metal compounds. Moreover, the compound which substituted the zirconium atom of the said transition metal compound by the titanium atom or the hafnium atom can also be illustrated.

  There is no restriction | limiting in particular in the quantity of the component (b) with respect to component (a) in manufacture of the ethylene-type polymer of this invention, It is preferable that it is 0.0001-100 times mole, Most preferably, it is 0.001-10. Double mole.

  As the metallocene catalyst using the component (a) and the component (b) in the method that can be used for the production of the ethylene polymer of the present invention, the component (a), the component (b), the organoaluminum compound [component (c )], A catalyst comprising component (a), component (b) and aluminoxane [component (d)], a catalyst comprising component (c), component (a) and component (b) A catalyst comprising at least one salt selected from a protonic acid salt [component (e)], a Lewis acid salt [component (f)] or a metal salt [component (g)], and further comprising a component (c) A catalyst comprising component (a), component (b), component (d), and inorganic oxide [component (h)], component (a), component (b), component (h), component (e), component (F) a catalyst comprising at least one salt selected from component (g); A catalyst comprising component (c), a catalyst comprising component (a), component (b), clay mineral [component (i)] and component (c), component (a), component (b) and an organic compound The catalyst comprising the clay mineral [component (j)] treated with the above can be exemplified, but preferably the catalyst comprising the component (a), the component (b) and the component (j) can be used.

  The clay mineral that can be used as the component (i) and the component (j) is fine particles mainly composed of microcrystalline silicate. Most of the clay minerals have a layered structure as a structural feature, and it can be mentioned that the layers have negative charges of various sizes. In this respect, it is greatly different from a metal oxide having a three-dimensional structure such as silica or alumina. These clay minerals are generally of a large layer charge, with pyrophyllite, kaolinite, dickite and talc groups (negative charge per chemical formula is approximately 0), smectite groups (negative charge per chemical formula is from about 0.25). 0.6), vermiculite group (negative charge per chemical formula is approximately 0.6 to 0.9), mica group (negative charge per chemical formula is approximately 1), brittle mica group (negative charge per chemical formula is approximately 2) It is classified. Each group shown here includes various clay minerals, and examples of the clay mineral belonging to the smectite group include montmorillonite, beidellite, saponite, hectorite and the like. Further, a plurality of the above clay minerals can be mixed and used.

  The organic compound treatment in component (j) refers to introducing an organic ion between clay mineral layers to form an ionic complex. Examples of the organic compound used in the organic compound treatment include N, N-dimethyl-n-octadecylamine hydrochloride, N, N-dimethyl-n-eicosylamine hydrochloride, N, N-dimethyl-n-docosylamine hydrochloride, N, N-dimethyloleylamine hydrochloride, N, N-dimethylbehenylamine hydrochloride, N-methyl-bis (n-octadecyl) amine hydrochloride, N-methyl-bis (n-eicosyl) amine hydrochloride, N-methyl -Dioleylamine hydrochloride, N-methyl-dibehenylamine hydrochloride, N, N-dimethylaniline hydrochloride can be exemplified.

  The catalyst comprising component (a), component (b) and component (j) can be obtained by contacting component (a), component (b) and component (j) in an organic solvent. The method of adding component (b) to the contact product of component (j) and component (b), the method of adding component (a) to the contact product of component (b) and component (j), component (a) and component (b) ) And a method of adding the contact product of component (a) and component (b) to component (j).

  As the contact solvent, aliphatic hydrocarbons such as butane, pentane, hexane, heptane, octane, nonane, decane, cyclopentane or cyclohexane, aromatic hydrocarbons such as benzene, toluene or xylene, ethyl ether or n-butyl ether And ethers such as methylene chloride and chloroform, 1,4-dioxane, acetonitrile and tetrahydrofuran.

  About a contact temperature, it is preferable to select between 0-200 degreeC and to process.

  The amount of each component used is 0.0001 to 100 mmol, preferably 0.001 to 10 mmol of component (a) per 1 g of component (j).

  The contact product of component (a), component (b) and component (j) prepared in this way may be used without washing, or may be used after washing. Further, when the component (a) or the component (b) is a dihalogen, it is preferable to further add the component (c). Further, component (c) can be added for the purpose of removing impurities in component (j), polymerization solvent and olefin.

  In the method that can be used for the production of the ethylene polymer of the present invention, the polymerization temperature is preferably -100 to 120 ° C, and particularly in consideration of productivity, the polymerization temperature is performed in the range of 20 to 120 ° C, and more preferably 60 to 120 ° C. Is preferred. The polymerization time is preferably in the range of 10 seconds to 20 hours, and the polymerization pressure is preferably in the range of normal pressure to 300 MPa. As a supply ratio of ethylene and a C3-C8 alpha-olefin, ethylene / C3-C8 alpha-olefin (molar ratio) is 1-200, Preferably it is 3-100, More preferably, it is 5-50. Feed rates can be used. It is also possible to adjust the molecular weight using hydrogen during polymerization. The polymerization can be carried out by any of batch, semi-continuous and continuous methods, and can be carried out in two or more stages by changing the polymerization conditions. In addition, the ethylene copolymer can be obtained by separating and recovering from the polymerization solvent by a conventionally known method after the completion of the polymerization and drying.

  Polymerization can be carried out in a slurry state, a solution state, or a gas phase state. In particular, when the polymerization is performed in a slurry state, an ethylene-based copolymer having a powder particle shape is efficiently and stably produced. Can do. Further, the solvent used for the polymerization may be any organic solvent that is generally used, and specific examples include benzene, toluene, xylene, propane, isobutane, pentane, hexane, heptane, cyclohexane, gasoline, and the like, propylene, Olefin itself such as 1-butene, 1-hexene and 1-octene can also be used as a solvent.

  The ethylene-based polymer obtained in the present invention can be applied to fields that can be conventionally used. For example, fields such as injection-molded products, films, sheets, blows, laminates, foams or fibers can be mentioned. Moreover, it can shape | mold by a normal shaping | molding method. As additives such as stabilizers, those used in the industry can be applied. In addition, other commonly known resins such as high density polyethylene, linear low density polyethylene, low density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, and ethylene / vinyl acetate copolymers. , Ethylene / vinyl alcohol copolymer, polystyrene, grafted products of these maleic anhydrides, etc., or a mixture of rubbers such as ethylene / propylene rubber, ethylene / butadiene rubber, ethylene / propylene / diene rubber. Furthermore, it can also be used in combination with a nucleating agent, an inorganic filler, a fiber or the like. Further, as with conventional polyolefins, maleic anhydride or the like can be subjected to modification such as graft reaction, crosslinking, and the like. The ethylene polymer of the present invention includes a heat stabilizer, a weather stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a slip agent, a lubricant, a nucleating agent, a pigment, carbon black, talc, glass powder, glass fiber, etc. Known additives such as inorganic fillers or reinforcing agents, organic fillers or reinforcing agents, flame retardants, and neutron shielding agents can be blended.

  According to the present invention, it is possible to obtain an ethylene polymer that is excellent in thermal stability and excellent in moldability in a wide range of molding temperatures.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, commercially available reagents were used.

  Preparation of the clay mineral [component (j)] treated with the organic compound, preparation of the ethylene polymer production catalyst, production of the ethylene polymer and solvent purification were all carried out in an inert gas atmosphere. Preparation of clay mineral [component (j)] treated with an organic compound, preparation of an ethylene polymer production catalyst, solvent used for the production of the ethylene polymer, etc. are all purified, dried and removed in advance by known methods. What used oxygen was used. Components (a) and (b) were synthesized and identified by known methods. A hexane solution (0.714M) of triisobutylaluminum manufactured by Tosoh Finechem Co., Ltd. was used.

  Furthermore, various physical properties of the ethylene-based polymer in the examples were measured by the following methods.

The weight average molecular weight (M _w ), the number average molecular weight (M _n ), and the ratio of the weight average molecular weight to the number average molecular weight (M _w / M _n ) were measured by gel permeation chromatography (GPC). Tosoh Co., Ltd. HLC-8121GPC / HT is used as the GPC apparatus, Tosoh Co., Ltd. TSKgel GMHhr-H (20) HT is used as the column, the column temperature is set to 140 ° C., and 1 is used as the eluent. Measurement was performed using 2,4-trichlorobenzene. A measurement sample was prepared at a concentration of 1.0 mg / ml, and 0.3 ml was injected and measured. The calibration curve of molecular weight is calibrated using a polystyrene sample having a known molecular weight. In addition, _Mw and _Mn were calculated | required as a value of linear polyethylene conversion.

  The density (d) was measured by a density gradient tube method in accordance with JIS K6760 (1995).

The number of terminal vinyls is 4000 cm ⁻¹ to 400 cm of a film prepared by hot-pressing an ethylene polymer using a SPECTRUM ONE Fourier transform infrared spectrophotometer (FT-IR) manufactured by Perkin Elmer, and then cooling with ice. It measured in the range of ^-1 and computed using the following formula.

Number of terminal vinyls per 1000 carbon atoms (pieces / 1000 C) = a × A / L / d
In the formula, a represents an absorptivity coefficient, A represents an absorbance of 909 cm ⁻¹ attributed to terminal vinyl, L represents a film thickness, and d represents a density. In addition, a was calculated | required from the analytical curve created using the sample which confirmed the number of terminal vinyls per 1000 carbon atoms from < ¹ > H-NMR measurement. ¹ H-NMR measurement was performed at 130 ° C. in a mixed solvent of deuterated benzene and o-dichlorobenzene using GSX400 manufactured by JEOL. The number of terminal vinyls per 1000 carbon atoms was calculated from the integral ratio of the peak attributed to methylene and the peak attributed to terminal vinyl. With respect to each peak, tetramethylsilane was used as a standard (0 ppm), and a peak with a chemical shift of 1.3 ppm was attributed to methylene and a peak with 4.8 to 5.0 ppm was assigned to terminal vinyl.

The ethylene polymer used for the measurement of the melt tension (MS ₁₆₀ , MS ₁₆₀ ) and the flow activation energy (E _a ) was previously used as a heat-resistant stabilizer Irganox 1010 ^™ (manufactured by Ciba Specialty Chemicals) 1,500 ppm, Irgafos 168 ^TM (manufactured by Ciba Specialty Chemicals Co., Ltd.) with 1,500 ppm added was used at 190 ° C. and rotation speed 30 rpm under nitrogen flow using an internal mixer (manufactured by Toyo Seiki Seisakusho, trade name: Labo Plast Mill). What kneaded for 30 minutes was used.

The activation energy (E _a ) of the flow was determined by using a disk-disk rheometer (trade name: MCR-300, manufactured by Anton Paar Co., Ltd.) at each of 150 ° C., 170 ° C., and 190 ° C. at an angular velocity of 0.1. The shear storage elastic modulus G ′ and the shear loss elastic modulus G ″ in the range of ˜100 rad / s were determined, the shift factor of the horizontal axis at a reference temperature of 150 ° C. was determined, and the following Arrhenius equation was used.
Viscosity (η _o ) = Aexp (E _a / RT)
In the formula, R is a gas constant.
The vertical axis is not moved.

Melt tension is measured by attaching a die with a length of 8mm and a diameter of 2.095mm to a capillary viscometer (Toyo Seiki Seisakusho, trade name: Capillograph) with a barrel diameter of 9.55mm so that the inflow angle is 90 °. did. In MS ₁₆₀ , the temperature was set to 160 ° C., the piston lowering speed was set to 10 mm / min, the stretch ratio was set to 47, and the load (mN) required for take-up was MS ₁₆₀ . When the maximum draw ratio was less than 47, the load (mN) required for taking up at the highest draw ratio that did not break was MS ₁₆₀ . The load (mN) measured by the same method with the temperature set at 190 ° C. was designated as MS ₁₉₀ .

  The thermal stability of the ethylene-based polymer is as follows. The ethylene-based polymer is not added with a heat-resistant stabilizer and is rotated at 190 ° C under a nitrogen stream using an internal mixer (product name: Labo Plast Mill, manufactured by Toyo Seiki Seisakusho). What was pelletized after kneading at several 30 rpm for 30 minutes was left in an oven set at 120 ° C. for 96 hours and evaluated by calculating the yellowing degree (ΔYI) by the method described in JIS K 7105. ΔYI is the amount of change in yellowness determined by the following formula. The smaller the ΔYI, the better the thermal stability.

ΔYI = YI−YI ₀
(Wherein, YI is the yellowness after heat treatment in an oven, YI ₀ is the yellowness before heating in an oven.)
Example 1
[Preparation of Clay Mineral {Component (j)} Treated with Organic Compound]
After adding 60 mL of ethanol and 2.0 mL of 37% concentrated hydrochloric acid to 60 mL of water, 6.6 g (0.022 mol) of N, N-dimethyl-octadecylamine was added to the resulting solution and heated to 60 ° C. A hydrochloride solution was prepared. To this solution was added 20 g of hectorite. The suspension was stirred at 60 ° C. for 3 hours, the supernatant was removed, and then washed with 1 L of 60 ° C. water. Then, the modified hectorite (component (m)) with an average particle diameter of 5.2 micrometers was obtained by drying at 60 degreeC and 10 < ^-3 > torr for 24 hours, and grind | pulverizing with a jet mill. As a result of elemental analysis, the amount of ions per gram of modified hectorite was 0.85 mmol.
[Preparation of ethylene-based copolymer production catalyst]
53 mg (160 μmol) of propane-1,3-diylbis (cyclopentadienyl) zirconium dichloride (component (a)) was suspended in 17.6 mL of hexane, and a hexane solution of triisobutylaluminum (component (c)) (0. 714M) 22.4 mL was added to obtain a contact product of component (a) and component (c). 4.0 g of the modified hectorite (component (l)) was added to the contact product, and the mixture was stirred at 60 ° C. for 3 hours, and then allowed to stand to remove the supernatant, and a hexane solution of triisobutylaluminum (0.03 M ). Further, a hexane solution (0.15 M) of triisobutylaluminum was added to form a catalyst slurry (100 g / L).

To the catalyst slurry prepared above, 3 mol% of diphenylmethylene (1-cyclopentadienyl) (2,7-di-tert-butyl-based on propane-1,3-diylbis (cyclopentadienyl) zirconium dichloride was added. 9-fluorenyl) zirconium dichloride (component (b)) 3.3 mg (4.9 μmol), hexane 7.2 mL, and a solution of triisobutylaluminum in hexane (0.714 M) 0.69 mL were added at room temperature. Stir for hours. Let stand and remove the supernatant, wash with hexane solution of triisobutylaluminum (0.03M), add hexane solution of triisobutylaluminum (0.15M) and finally add 100g / L catalyst slurry. Obtained.
[Production of ethylene copolymer]
Into a 2 L autoclave, 1,200 mL of hexane, 36 g of 1-butene, and 1.0 mL of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 75 ° C. To the autoclave, 0.25 mL of the catalyst slurry was added, and an ethylene / hydrogen mixed gas (hydrogen: 700 ppm included) was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 1.2 MPa. The polymerization temperature was controlled at 75 ° C. After 60 minutes from the start of polymerization, the internal pressure of the autoclave was released, and the content was suction filtered. After drying, 45 g of polymer was obtained. Table 1 shows the density, MFR, terminal vinyl number, Mw / Mn, MS ₁₆₀ , MS ₁₉₀ , E _a , and ΔYI of the obtained ethylene copolymer.

Example 2
[Production of ethylene copolymer]
Polymerization was conducted in the same manner as in Example 1 except that 72 g of 1-butene was used and the polymerization time was 25 minutes. As a result, 46 g of polymer was obtained. Table 1 shows the density, MFR, terminal vinyl number, Mw / Mn, MS ₁₆₀ , MS ₁₉₀ , E _a , and ΔYI of the obtained ethylene copolymer.

Example 3
[Preparation of ethylene polymer production catalyst]
63 mg (160 μmol) of 1,1,3,3-tetramethyldisiloxane-1,3-diylbis (cyclopentadienyl) zirconium dichloride (component (a)) was suspended in 17.6 mL of hexane, and triisobutylaluminum ( 22.4 mL of a hexane solution (0.714M) of component (c)) was added to obtain a contact product of component (a) and component (c). 4.0 g of the modified hectorite (component (l)) prepared in Example 1 [Preparation of clay mineral {component (j)} treated with an organic compound]) was added to this contact product, and the mixture was heated at 60 ° C. for 3 hours. After stirring, the solution was left to stand to remove the supernatant, and washed with a hexane solution (0.03M) of triisobutylaluminum. Further, a hexane solution (0.15 M) of triisobutylaluminum was added to form a catalyst slurry (100 g / L).

In the catalyst slurry prepared above, 5 mol% of diphenylmethylene (1-cyclopentadienyl) with respect to 1,1,3,3-tetramethyldisiloxane-1,3-diylbis (cyclopentadienyl) zirconium dichloride. 5.6 mg (8.4 μmol) of (2,7-di-tert-butyl-9-fluorenyl) zirconium dichloride (component (b)), 6.7 mL of hexane and a hexane solution of triisobutylaluminum (0.714 M) A solution consisting of 18 mL was added and stirred at room temperature for 6 hours. Let stand and remove the supernatant, wash with hexane solution of triisobutylaluminum (0.03M), add hexane solution of triisobutylaluminum (0.15M) and finally add 100g / L catalyst slurry. Obtained.
[Production of ethylene polymer]
Into a 2 L autoclave, 1,200 mL of hexane and 1.0 mL of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To this autoclave, 0.075 mL of the catalyst slurry was added, and an ethylene / hydrogen mixed gas (hydrogen: 1000 ppm included) was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 90 g of polymer was obtained. Table 1 shows the density, MFR, number of terminal vinyls, Mw / Mn, MS ₁₆₀ , MS ₁₉₀ , E _a and ΔYI of the obtained ethylene polymer.

Example 4
[Preparation of ethylene-based copolymer production catalyst]
10 mol% of isopropylidene (1-cyclopentadienyl) (2,7-di-tert) with respect to 1,1,3,3-tetramethyldisiloxane-1,3-diylbis (cyclopentadienyl) zirconium dichloride -A solution consisting of 9.7 mg (17.8 μmol) of butyl-9-fluorenyl) zirconium dichloride (component (b)), 5.4 mL of hexane, and 2.5 mL of a hexane solution of triisobutylaluminum (0.714 M) was added. Except for the above, preparation was carried out in the same manner as in Example 3 [Preparation of ethylene polymer production catalyst].
[Production of ethylene copolymer]
Into a 2 L autoclave, 1,200 mL of hexane and 1.0 mL of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To this autoclave, 0.075 mL of the catalyst slurry was added, and an ethylene / hydrogen mixed gas (hydrogen: 2500 ppm included) was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 91 g of polymer was obtained. Table 1 shows the density, MFR, number of terminal vinyls, Mw / Mn, MS ₁₆₀ , MS ₁₉₀ , E _a and ΔYI of the obtained ethylene polymer.

Comparative Example 1
[Production of ethylene polymer]
Into a 2 L autoclave, 1,200 mL of hexane and 0.08 mL of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 90 ° C. To this autoclave, 72.5 mg of Ineosilicas Cr catalyst (EP350) was added, hydrogen gas was introduced until the partial pressure reached 1.0 MPa, and ethylene gas was introduced until the partial pressure reached 1.0 MPa. Polymerization was started. During the polymerization, ethylene gas was continuously introduced so that the ethylene partial pressure was maintained. The polymerization temperature was controlled at 90 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 143 g of polymer was obtained. Table 1 shows the density, MFR, number of terminal vinyls, Mw / Mn, MS ₁₆₀ , MS ₁₉₀ , E _a and ΔYI of the obtained ethylene polymer. As a result of evaluating the ΔYI of the ethylene polymer, the number of terminal vinyls per 1,000 carbon atoms exceeded 0.2, and it was confirmed that the ethylene polymer was inferior in thermal stability.

Comparative Example 2
Table 1 shows the density, MFR, number of terminal vinyls, Mw / Mn, MS ₁₆₀ , MS ₁₉₀ , and E _a of the metallocene catalyst ethylene / 1-octene copolymer (AF1840) commercially available from Dow Chemical. The present ethylene copolymer deviates from the requirements of the formulas (1) and (3).

Comparative Example 3
Table 1 shows the density, MFR, number of terminal vinyls, Mw / Mn, MS ₁₆₀ , MS ₁₉₀ , and E _a of the high pressure LDPE (Petrocene 176R) commercially available from Tosoh Corporation. The present ethylene polymer deviates from the requirements of the formulas (2) and (3).

Comparative Example 4
Density of Tosoh Corporation pressure method are commercially available LDPE (Petrocene 360), MFR, terminal number vinyl _{shows Mw} / Mn, the _{MS 160,} MS _{190, E a} in Table 1. The present ethylene polymer deviates from the requirements of the formulas (2) and (3).

Claims (2)

It consists of a repeating unit derived from ethylene, or a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms, and satisfies the following (A) to (G): Ethylene polymer.
(A) The density [d (kg / m ³ )] is 910 or more and 970 or less,
(B) The melt flow rate [MFR (g / 10 min)] measured at 190 ° C. and a load of 2.16 kg is 0.01 to 50,
(C) the number of terminal vinyls is 0.2 or less per 1,000 carbon atoms,
(D) The melt tension [MS ₁₆₀ (mN)] and MFR measured at 160 ° C. satisfy the following formula (1),
MS ₁₆₀ > 90-130 × log (MFR) (1)
(E) Melt tension [MS ₁₉₀ (mN)] measured at 190 ° C. and MS ₁₆₀ satisfy the following formula (2):
MS ₁₆₀ / MS ₁₉₀ <1.8 (2)
(F) Flow activation energy [E _a (kJ / mol)] and d satisfy the following formula (3).
_{127-0.107d <E a <88-0.060d (3} )
(G) The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 2 or more and 6 or less. The ethylene-based polymer according to claim 1, wherein (A) 'd is 910 or more and 940 or less.