JP2009001814A - Film formed from ethylene polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film formed from an ethylene-α-olefin copolymer excellent in the extrusion moldability and in the balance between the appearance and the impact resistance of an extrusion molding. <P>SOLUTION: The ethylene-α-olefin copolymer contains a constitutional unit derived from ethylene and a constitutional unit derived from a 4-20C α-olefin and is characterized in that the melt flow rate is 1.65-2.18 g/10 min, the melt tension at 190°C is 2.9-3.3 cN, and the molecular weight distribution (Mw/Mn) is 9.2-16.6. The film is obtained by inflation molding an ethylene-α-olefin copolymer having a SR (swell ratio) value of 1.28-1.45 and characterized in that the haze at a thickness of 30 μm is 6.3-9.1% and the impact resistance is 820-950 kJ/m<SP>2</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a film made of an ethylene-α-olefin copolymer. More specifically, the present invention relates to a film made of an ethylene-α-olefin copolymer excellent in balance between extrusion processability, appearance and impact strength of an extruded product.

  Ethylene-based polymers are used in many fields as general-purpose resins, and are used, for example, in extruded products such as films and sheets. For extruded products, molding processability such as extrusion torque and melt tension, mechanical properties such as rigidity and impact strength, and appearance such as surface smoothness, gloss and transparency of films and sheets (optical It is required to have excellent properties.

  For example, JP-A-4-213309 discloses an ethylene copolymer having excellent melt tension and a narrow composition distribution from a structural unit derived from ethylene and a structural unit derived from an α-olefin having 3 to 20 carbon atoms. An ethylene copolymer having a density of 0.86 to 0.95 g / cm 3, an MFR of 0.001 to 50 g / 10 min, a melt tension and MFR satisfying a specific relationship, An ethylene-based copolymer is described in which the temperature and density at the maximum peak position in the measured endothermic curve satisfy a specific relationship.

  Although the ethylene copolymers described in the above-mentioned JP-A-4-213309 etc. have a high melt tension, the appearance of the extruded product may not necessarily satisfy the requirements. Further improvements have been desired for the extrusion processability of ethylene-based copolymers, the appearance and impact strength of extruded products, and the balance.

JP-A-4-213309

  An object of the present invention is to provide an ethylene-α-olefin copolymer excellent in the balance between extrusion processability, appearance of an extrusion-molded product and impact strength.

As a result of the study, the present inventors have found that the present invention can solve the above-described problems, and have completed the present invention.
That is, one aspect of the present invention is
An ethylene-α-olefin copolymer comprising a structural unit derived from ethylene and a structural unit derived from an α-olefin having 4 to 20 carbon atoms, wherein the melt flow rate (MFR; unit is g / 10 minutes) Is 1.65 or more and 2.18 or less, melt tension (MT; unit is cN) at 190 ° C. is 2.9 or more and 3.3 or less, and molecular weight distribution (Mw / Mn) is A film obtained by inflation molding an ethylene-α-olefin copolymer having a 9.2 to 16.6 SR and an SR of 1.28 to 1.45, and having a haze (unit: 30 μm) %) Is from 6.3 to 9.1 and the impact strength (TI; unit is kJ / m ² ) is from 820 to 950 .

  ADVANTAGE OF THE INVENTION According to this invention, the ethylene-alpha-olefin copolymer excellent in the balance with extrusion processability, the external appearance of an extrusion molded product, and impact strength can be obtained.

  The ethylene-α-olefin copolymer of the present invention is an ethylene-α-olefin copolymer containing a structural unit derived from ethylene and a structural unit derived from an α-olefin having 4 to 20 carbon atoms.

  The structural unit derived from ethylene is a unit derived from ethylene as a monomer and contained in the ethylene-α-olefin copolymer. The structural unit derived from an α-olefin having 4 to 20 carbon atoms is a unit derived from an α-olefin having 4 to 20 carbon atoms as a monomer and contained in an ethylene-α-olefin copolymer. is there. Examples of the α-olefin having 4 to 20 carbon atoms include 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene and the like. More preferred are 4-methyl-1-pentene and 1-hexene.

  Content of the structural unit induced | guided | derived from ethylene is 50 to 99 weight% with respect to the total weight (100 weight%) of an ethylene-alpha-olefin copolymer. Content of the structural unit induced | guided | derived from a C4-C20 alpha olefin is 1-50 weight% with respect to the total weight (100 weight%) of an ethylene-alpha-olefin copolymer.

  The ethylene-α-olefin copolymer of the present invention is a structural unit derived from a monomer other than the structural unit derived from ethylene and a structural unit derived from an α-olefin having 4 to 20 carbon atoms. It may contain. Examples of other monomers include conjugated dienes (for example, butadiene and isoprene), non-conjugated dienes (for example, 1,4-pentadiene), acrylic acid, acrylic acid esters (for example, methyl acrylate and ethyl acrylate), and methacrylic acid. Methacrylic acid esters (for example, methyl methacrylate and ethyl methacrylate), vinyl acetate and the like.

  The ethylene-α-olefin copolymer of the present invention is preferably a copolymer of ethylene and an α-olefin having 5 to 10 carbon atoms, more preferably ethylene and an α-olefin having 6 to 10 carbon atoms. It is a copolymer. Examples thereof include an ethylene / 1-hexene copolymer, an ethylene-4-methyl-1-pentene copolymer, and an ethylene-1-octene copolymer, and an ethylene-1-hexene copolymer is preferable. A terpolymer of ethylene, an α-olefin having 6 to 10 carbon atoms and 1-butene is also preferable. For example, ethylene-1-butene-1-hexene copolymer, ethylene-1-butene-4-methyl Examples include a -1-pentene copolymer and an ethylene-1-butene-1-octene copolymer, and an ethylene-1-butene-1-hexene copolymer is more preferable.

  The melt flow rate (MFR, unit g / 10 min) of the ethylene-α-olefin copolymer of the present invention is 1 or more and 100 or less, preferably 1 or more and 20 or less, more preferably 1.2 or more and 10 or less. Or less, more preferably 1.4 or more and 6 or less.

  In the present invention, the melt flow rate (MFR; unit is g / 10 minutes) was measured at 190 ° C. with a load of 21.18 N (2.16 Kg) according to the method defined in JIS K7210-1995. Value. And the polymer which mix | blended antioxidant 1000ppm previously is used for the measurement of said melt flow rate.

The ethylene-α-olefin copolymer of the present invention has a melt flow rate (MFR; the unit is g / 10 minutes) and a melt tension at 190 ° C. (MT; the unit is cN) represented by the following formula ( It satisfies the relationship 1).
2 x MFR ^-0.59 <MT <20 x MFR ^-0.59 Formula (1)

It is generally known that there is a relationship between the melt flow rate (MFR) and melt hearing of an ethylene-α-olefin copolymer, for example, the melt tension decreases as the MFR increases. .
The ethylene-α-olefin copolymer of the present invention is considered to have a polymer structure such as a long chain branch, and since it has such a polymer structure as a long chain branch, the ethylene-α- It is considered that the melt hearing of the olefin copolymer is higher than the melt hearing of the conventional ethylene-α-olefin copolymer and falls within an appropriate range.

The ethylene-α-olefin copolymer of the present invention is excellent in extrusion processability in order to satisfy the relationship of the above formula (1). When the melt tension is too low and the relationship of 2 × MFR ^−0.59 <MT is not satisfied in the formula (1), the extrusion processability may be deteriorated, and the melt tension is too high, in the formula (1). When MT <20 × MFR ^−0.59 is not satisfied, high-speed take-up processing may be difficult.

The relationship between the melt flow rate (MFR) and the melt tension (MT) satisfied by the ethylene-α-olefin copolymer of the present invention is more preferably 2.2 × MFR ^−0.59 <MT <15 than the relationship of the formula (1). × MFR ^-0.59
And more preferably
2.5 × MFR ^-0.59 <MT <10 × MFR ^-0.59
It is.

  The melt tension (MT; unit is cN) in the above formula (1) is a piston at 190 ° C. and an extrusion speed of 5.5 mm / min using a melt tension tester sold by Toyo Seiki Seisakusho. When the molten resin strand is extruded from an orifice having a diameter of 2.09 mmφ and a length of 8 mm, and the strand is wound up by using a roller having a diameter of 50 mm while increasing the rotational speed by 40 rpm / min, the strand is cut. The previous tension value.

In the ethylene-α-olefin copolymer of the present invention, the intrinsic viscosity ([η]; the unit is dl / g) and the MFR satisfy the relationship of the following formula (2).
1.02 × MFR ^−0.094 <[η] <1.50 × MFR ^−0.156 Formula (2)

It is generally known that there is a relationship between the MFR and intrinsic viscosity of an ethylene-α-olefin copolymer, for example, the intrinsic viscosity decreases as the MFR increases.
The ethylene-α-olefin copolymer of the present invention is considered to have a polymer structure such as a long chain branch, and since it has such a polymer structure as a long chain branch, the ethylene-α- It is considered that the intrinsic viscosity of the olefin copolymer is lower than the intrinsic viscosity of the conventional ethylene-α-olefin copolymer and falls within an appropriate range.

Since the ethylene-α-olefin copolymer of the present invention satisfies the relationship of the above formula (2), the extrusion torque is low and the extrusion processability is excellent. If the intrinsic viscosity ([η]) is too low and the relationship of 1.02 × MFR ^−0.094 <[η] is not satisfied in the formula (2), the impact strength may be reduced, and the intrinsic viscosity ([η ]) Is too high, and in equation (2), ^if the relationship [η] <1.50 × MFR ^−0.156 is not satisfied, the extrusion torque may be high and the extrusion processability may be poor.

As the relationship between the melt flow rate (MFR) and the intrinsic viscosity ([η]) satisfied by the ethylene-α-olefin copolymer of the present invention, more preferably than the relationship of formula (2),
1.05 × MFR ^−0.094 <[η] <1.47 × MFR ^−0.156
And more preferably
1.08 × MFR ^−0.094 <[η] <1.42 × MFR ^−0.156
It is.

The intrinsic viscosity ([η]; the unit is dl / g) in the above formula (2) is obtained by adding ethylene-α-olefin to 100 ml of tetralin containing 5% by weight of butylhydroxytoluene (BHT) as a thermal degradation inhibitor. After preparing a sample solution by dissolving 100 mg of the copolymer at 135 ° C., and determining the relative viscosity (ηrel) at 135 ° C. calculated from the falling time of the sample solution and the blank solution using an Ubbelohde viscometer Is calculated from the following equation. The blank solution is tetralin containing only 5% by weight of BHT as a thermal deterioration preventing agent.
[Η] = 23.3 × log (ηrel)

The ethylene-α-olefin copolymer of the present invention is the most log normal distribution curve obtained by dividing the chain length distribution curve obtained by gel permeation chromatography measurement into at least two log normal distribution curves. The chain length A at the peak position of the logarithmic normal distribution curve corresponding to the component having a high molecular weight and the MFR satisfy the relationship of the following formula (3).
3.30 <logA <−0.0815 × log (MFR) +4.05 Formula (3)

  Since the ethylene-α-olefin copolymer of the present invention satisfies the relationship of the above formula (3), the melt tension is high and the extrusion processability is excellent, or the extrusion torque is low and the extrusion processability is excellent. Excellent appearance of extruded products.

As the relationship between the melt flow rate (MFR) and the chain length A (log A) satisfied by the ethylene-α-olefin copolymer of the present invention, more preferably than the relationship of formula (3),
3.30 <logA <−0.0815 × log (MFR) +4.03
And more preferably
3.30 <logA <−0.0815 × log (MFR) +4.02
It is.

The chain length distribution curve can be obtained by gel permeation chromatography measurement under the following conditions (1) to (6).
(1) Apparatus: Waters 150C manufactured by Water
(2) Separation column: TOSOH TSKgelGMH-HT
(3) Measurement temperature: 145 ° C
(4) Carrier: orthodichlorobenzene (5) Flow rate: 1.0 mL / min (6) Injection volume: 500 μL

The chain length distribution curve is divided as follows.
First, a chain length distribution curve in which a weight ratio dW / d (logAw) (y value) is plotted against logAw (x value) that is the logarithm of chain length Aw is measured by gel permeation chromatography measurement. The number of plot data is usually at least 300 or more so as to form a continuous distribution curve. Next, four lognormal distribution curves (xy) having a standard deviation of 0.30 and an arbitrary average value (usually corresponding to the chain length A of the peak position) with respect to the above x value. Curve) is added at an arbitrary ratio to create a composite curve. Further, the average value and the ratio are obtained so that the deviation sum of squares of the y value with respect to the same x value of the actually measured chain length distribution curve and the combined curve becomes a minimum value. The minimum value of the deviation sum of squares is usually 0.5% or less with respect to the deviation sum of squares when the ratios of the peaks are all zero. The logarithm corresponding to the component having the highest molecular weight among the lognormal distribution curves obtained by dividing the logarithmic normal distribution curve into four lognormal distribution curves when the average value and the ratio giving the minimum value of the deviation sum of squares are obtained. Log A is calculated from the chain length A at the peak position of the normal distribution curve. The ratio of the peak of the lognormal distribution curve corresponding to the highest molecular weight component is usually 10% or more.

In the ethylene-α-olefin copolymer of the present invention, the characteristic relaxation time at 190 ° C. (τ; the unit is sec) and the MFR satisfy the relationship of the following formula (4).
2 <τ <8.1 × MFR ^-0.746 formula (4)

  In order to satisfy the relationship of the above formula (4), the ethylene-α-olefin copolymer of the present invention has a high melt tension and excellent extrusion processability, or a low extrusion torque and excellent extrusion processability. Excellent appearance of extruded products such as films.

The relationship between the melt flow rate (MFR) and the characteristic relaxation time (τ) satisfied by the ethylene-α-olefin copolymer of the present invention is more preferably the relationship of the formula (4),
2 <τ <7.9 × MFR ^-0.746
And more preferably
2 <τ <7.8 × MFR ^-0.746
It is.

  The characteristic relaxation time (τ) at 190 ° C. is measured at each temperature T (K) measured under the following conditions (1) to (4) using a Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics as a viscoelasticity measuring device. ) Is shifted on the basis of the temperature-time superposition principle, and the shear rate (ω: unit is rad / unit) of the dynamic viscosity (η; unit is Pa · sec) at 190 ° C. This is a numerical value calculated when a master curve showing dependency is obtained and the master curve is approximated by the following cross equation.

Measurement conditions of dynamic viscoelasticity data at each temperature T (K) (1) Geometry: Parallel plate, diameter 25 mm, plate interval: 1.5-2 mm
(2) Strain: 5%
(3) Shear rate: 0.1 to 100 rad / sec
(4) Temperature: 190, 170, 150, 130 ° C
In addition, an appropriate amount (for example, 1000 ppm or more) of an antioxidant such as Irganox 1076 is blended in advance in the sample, and all measurements are performed under nitrogen.

Cloth's approximate expression η = η0 / [1+ (τ × ω) ⁿ ]
(Η0 and n are constants determined for each ethylene-α-olefin copolymer used in the measurement, similarly to the characteristic relaxation time τ.)
In addition, Rheometrics Rhios V. is used as a calculation software for creating a master curve and cross-type approximation. Use 4.4.4.

  The molecular weight distribution of the ethylene-α-olefin copolymer of the present invention is preferably 3.5 to 25, more preferably from the viewpoint of extrusion torque, extrusion processability, smoke generation and fluidity during extrusion process. Is 4.0-20, more preferably 7.5-17. The above-mentioned molecular weight distribution is a polystyrene equivalent weight average molecular weight (Mw) and number average molecular weight (Mn) calculated for the chain length distribution obtained by the gel permeation chromatography measurement, and Mw is divided by Mn. Value (Mw / Mn).

The density of the ethylene-α-olefin copolymer of the present invention is usually 890 to 970 kg / m ³ , and is a value measured according to the method defined in JIS K6760-1981. The density is preferably 905 to 940 kg / m ³ , more preferably 907 to 930 kg / m ³ from the viewpoint of the balance between rigidity and impact strength of the film obtained from the ethylene-α-olefin copolymer of the present invention. m is ^3.

  The flow activation energy (Ea, unit is kJ / mol) of the ethylene-α-olefin copolymer of the present invention is preferably 40 kJ / mol or more, more preferably from the viewpoint of fluidity. It is 45 kJ / mol or more, more preferably 50 kJ / mol or more.

The above flow activation energy (Ea) is measured under the same conditions as when the characteristic relaxation time (τ) is calculated using a Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics as a viscoelasticity measuring device. When dynamic viscoelasticity data at each temperature T (K) is shifted based on the temperature-time superposition principle, it is a numerical value calculated from the Arrhenius type equation of the following shift factor (a _T ), It is an index of sex.

Arrhenius type equation of shift factor (a _T ) log (a _T ) = Ea / R (1 / T−1 / T ₀ )
(R is a gas constant and T ₀ is a reference temperature (463 K).)
The calculation software includes Rheometrics Rhios V. 4.4.4, and in the Arrhenius plot log (a _T ) − (1 / T), the Ea value when the correlation coefficient r ₂ obtained when performing linear approximation is 0.99 or more is It is set as the activation energy of the flow of the ethylene-α-olefin copolymer of the present invention.

  The melt flow rate ratio (MFRR) of the ethylene-α-olefin copolymer of the present invention is usually 60 or more from the viewpoint of fluidity, and the ethylene-α having a melt flow rate ratio (MFRR) of 60 or more. -The olefin copolymer has a low extrusion torque and is excellent in extrusion processability.

  The melt flow rate ratio (MFRR) is a value obtained by measuring a melt flow rate value measured at 190 ° C. under a load of 211.82 N (21.60 kg) according to a method defined in JIS K7210-1995 with a load of 21.18 N (2 .16 kg) divided by the melt flow rate value. In addition, the polymer which mix | blended 1000 ppm of antioxidant previously was used for said melt flow rate measurement.

As the melting point (unit is ° C.) of the ethylene-α-olefin copolymer of the present invention, when the density is 927 kg / m ³ or less, at least two melting points are usually present from the viewpoint of heat resistance. The maximum melting point (Tmax) is 115 ° C. or higher, preferably 118 ° C. or higher. However, even if there is only one melting point and the melting point is 115 ° C. or lower, a melting component of 118 ° C. or higher is present.

  The above melting point is a differential scanning calorimeter DSC-7 manufactured by PerkinElmer, and 8 to 12 mg of sample is packed in an aluminum pan and held at 150 ° C. for 2 minutes, and then up to 40 ° C. at 5 ° C./min. The melting peak temperature observed when the temperature is lowered and held at 40 ° C. for 2 minutes and then raised to 150 ° C. at 5 ° C./min. Among them, the temperature at the highest melting peak position is defined as the maximum melting point Tmax.

The method for producing an ethylene-α-olefin copolymer of the present invention is a method of copolymerizing ethylene and an α-olefin under hydrogen conditions using the following metallocene olefin polymerization catalyst.
The metallocene olefin polymerization catalyst used in the production of the ethylene-α-olefin copolymer of the present invention is obtained by contacting the co-catalyst carrier (A), the crosslinked bisindenyl zirconium complex (B) and the organoaluminum compound (C). The promoter support (A) is diethyl zinc (a), fluorinated phenol (b), water (c), silica (d) and (e) trimethyldisilazane (((CH ₃ ) is a ₃ Si) ₂ NH) carrier obtained by contacting the.

The amount of each compound (a), (b), (c) used is not particularly limited, but the molar ratio of the amount of each compound used is (a) :( b) :( c) = 1: y: z It is preferable that y and z satisfy the following formula (3).
| 2-y-2z | ≦ 1 (3)
In the above formula (3), y is preferably a number of 0.01 to 1.99, more preferably a number of 0.10 to 1.80, and still more preferably a number of 0.20 to 1.50. Yes, most preferably a number from 0.30 to 1.00.

  The amount of (d) used for (a) is the amount of zinc atoms derived from (a) contained in the particles obtained by contact between (a) and (d) in 1 g of the obtained particles. The amount of zinc atoms contained is preferably 0.1 mmol or more, and more preferably 0.5 to 20 mmol. The amount of (e) used relative to (d) is preferably (e) 0.1 mmol or more per 1 g of (d), more preferably 0.5 to 20 mmol. preferable.

The cross-linked bisindenyl zirconium complex (B) is preferably racemic-ethylenebis (1-indenyl) zirconium dichloride or racemic-ethylenebis (1-indenyl) zirconium diphenoxide.
The organoaluminum compound (C) is preferably triisobutylaluminum or trinormaloctylaluminum.

The amount of the bridged bisindenyl zirconium complex (B) used is preferably 5 × 10 ^{−6 to} 5 × 10 ⁻⁴ mol with respect to 1 g of the promoter support (A). The amount of the organoaluminum compound (C) used is preferably the ratio of the number of moles of aluminum atoms in the organoaluminum compound (C) to the number of moles of zirconium atoms in the crosslinked bisindenylzirconium complex (B) (Al / Zr). And 1 to 2000.

The polymerization method is preferably a polymerization method involving the formation of ethylene-α-olefin copolymer particles, such as gas phase polymerization, slurry polymerization, and bulk polymerization, and preferably gas phase polymerization.
The gas phase polymerization reaction apparatus is usually an apparatus having a fluidized bed type reaction tank, and preferably an apparatus having a fluidized bed type reaction tank having an enlarged portion. A stirring blade may be installed in the reaction vessel.

As a method of supplying each component of the metallocene-based olefin polymerization catalyst used for the production of the ethylene-α-olefin copolymer of the present invention to the reaction vessel, usually an inert gas such as nitrogen or argon, hydrogen, ethylene, etc. And a method of supplying in a water-free state, and a method of supplying each component in a solution or slurry after dissolving or diluting each component in a solvent. Each component of the catalyst may be supplied individually, or arbitrary components may be supplied in contact in advance in an arbitrary order.
Moreover, it is preferable to carry out prepolymerization before carrying out the main polymerization and to use the prepolymerized prepolymerized catalyst component as a catalyst component or catalyst for the main polymerization.

The polymerization temperature is usually below the temperature at which the copolymer melts, preferably 0 to 150 ° C, more preferably 30 to 100 ° C.
Further, hydrogen may be added as a molecular weight regulator for the purpose of regulating the melt fluidity of the copolymer. An inert gas may coexist in the mixed gas.

  The ethylene-α-olefin copolymer of the present invention is considered to have a polymer structure such as long chain branching. And as a polymer structure like a long chain branch, it is thought that the structure intertwined closely is preferable. Such a tightly intertwined structure provides a higher flow activation energy than the conventional ethylene-α-olefin copolymer, and is thought to further improve the extrusion moldability.

  As described above, the flow activation energy (Ea, unit is kJ / mol) of an ethylene-α-olefin copolymer that is considered to be a structure in which polymer structures such as long chain branches are closely intertwined. ) Is preferably 60 kJ / mol or more, more preferably 63 kJ / mol or more, and still more preferably 66 kJ / mol or more, from the viewpoint of increasing melt tension at low temperature and obtaining sufficient moldability. is there. From the viewpoint of obtaining sufficient moldability without lowering the melt viscosity at a high temperature, and from the viewpoint of preventing the appearance of the surface of an extrusion-molded product such as a film from being roughened, Ea is preferably 100 kJ / mol or less, more preferably 90 kJ / mol or less.

As described above, the preferred ethylene polymer of the present invention, which is considered to be a structure in which a polymer structure such as a long chain branch is closely entangled, has a swell ratio (SR) and an intrinsic viscosity ([η]; The unit is dL / g) and the relationship of the following formula (5) or formula (6) is satisfied.
If [η] <1.20,
−0.91 × [η] +2.262 <SR <2 Formula (5)
If [η] ≧ 1.20,
1.17 <SR <2 Formula (6)

It is generally known that there is a relationship between the intrinsic viscosity ([η]) and the swell ratio (SR) of an ethylene polymer, for example, the swell ratio increases as the intrinsic viscosity decreases. .
The ethylene polymer of the present invention is considered to have a polymer structure such as a long chain branch, and the preferred ethylene polymer of the present invention has a structure that is closely entangled as a polymer structure such as a long chain branch. It is thought that there is. And, by such a tightly entangled structure, the SR of the ethylene polymer of the present invention is considered to be higher than the conventional ethylene polymer and within a preferable range, and [η] and SR of the ethylene polymer of the present invention Satisfies the above formula (5) or formula (6).

  When the ethylene-α-olefin copolymer of the present invention satisfies the relationship of the above formula (5) or formula (6), the extrusion torque is low, the stability during extrusion molding is excellent, and the film Thus, the surface of the extrusion-molded product is not roughened, and the appearance is excellent.

As the relationship of the formula (5) or (6) that the ethylene-α-olefin copolymer of the present invention satisfies,
If [η] <1.23,
−0.91 × [η] +2.289 <SR <1.9
When [η] ≧ 1.23,
1.17 <SR <1.9
And more preferably
If [η] <1.30,
−0.91 × [η] +2.353 <SR <1.8
When [η] ≧ 1.30,
1.17 <SR <1.8
It is.

The swell ratio (SR) in the above formula (5) or formula (6) was extruded into a strand with a load of 21.18 N (2.16 Kg) at 190 ° C. when measuring the melt flow rate (MFR). About the solid strand obtained by cooling in air later, the diameter D (unit is mm) at one point in the range of 1 to 6 mm from the tip is obtained, and the diameter is the orifice diameter 2.095 mm (D ₀ ). The value divided by (D / D ₀ ). The diameter D was obtained as an average value of three strand samples.

  A preferred ethylene-α-olefin copolymer of the present invention, that is, an ethylene-α-olefin copolymer having a flow activation energy (Ea) of 60 kJ / mol or more, or the above formula (5) or formula (6) The ethylene-α-olefin copolymer satisfying the above-mentioned relationship, which is considered to have a structure intertwined as a polymer structure such as a long chain branch, Using the metallocene-based olefin polymerization catalyst, ethylene and α-olefin are copolymerized under hydrogen conditions, and then kneaded by the following continuous extrusion granulation method.

  One of the methods is to continuously form a strand using an extruder equipped with an extension flow kneading (EFM) die developed by Utracki et al. Described in US Pat. No. 5,451,106. Is continuously cut to produce pellets. One of the methods is a method in which a strand is continuously formed using an extruder equipped with a different-direction twin screw having a gear pump, and the strand is continuously cut to produce a pellet. In the latter, it is preferable that there is a staying part between the screw part and the die.

The use of the ethylene-α-olefin copolymer of the present invention is preferably an extruded product such as a film or a sheet.
As a method for forming a film, for example, an ethylene-α-olefin copolymer of the present invention is melted, extruded from a circular die, and inflated into a cylindrical shape to produce a film. Examples include a T-die film forming method in which the ethylene-α-olefin copolymer of the present invention is melted, extruded from a linear die to produce a film, and the film is wound.

  You may make the ethylene-alpha-olefin copolymer of this invention contain a well-known additive as needed. Examples of the additives include antioxidants, weathering agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, dripping agents, pigments, fillers, and the like.

EXAMPLES Next, although this invention is demonstrated based on an Example, this invention is not limited to these Examples at all.
About the external appearance of the extrusion molded product in an Example, it evaluated using the film obtained by the following method.

(1) Film processing Using ethylene-α-olefin copolymer as a sample, Placo, 30 mmφ, L / D = 28, single axis extruder with full flight type screw, 50 mmφ, lip gap 0.8 mm die, two Using a heavy slit air ring, a film having a thickness of 30 μm was obtained by forming a film under conditions of a processing temperature of 170 ° C., an extrusion rate of 5.5 kg / hr, a frost line distance (FLD) of 200 mm, and a blow ratio of 1.8.

(2) Fish Eye The number of protrusions (fish eyes) on the film surface obtained above was observed visually. When the number of fish eyes was 100 or less per 1 m ² , it was evaluated as ◯, when it was 100 to 1000, Δ, and when it exceeded 1000, it was evaluated as ×.

(3) Haze (degree of itchiness)
According to the method prescribed | regulated to ASTMD1003, the haze value of the film obtained above was measured. It shows that transparency is excellent, so that this value is small.

Example 1
[Preparation of catalyst components]
(1) Silica treatment Silica heated at 300 ° C. under nitrogen flow in a nitrogen-substituted 3 liter four-necked flask (Sypolol 948 manufactured by Devison; average particle size = 61 μm; pore volume = 1.70 ml / g) Specific surface area = 291 m ² / g) 0.2 kg was added, and then 1.2 liters of toluene was added while washing the silica adhering to the wall of the flask. After cooling to 5 ° C., a mixed solution of 1,1,1,3,3,3-hexamethyldisilazane 84.4 ml (0.4 mmol) and toluene 115 ml was added dropwise over 25 minutes. After completion of the dropping, the mixture was stirred at 5 ° C. for 1 hour and then at 95 ° C. for 3 hours and filtered. Thereafter, the filter was washed four times with 1.2 liters of toluene at 95 ° C. Then, after adding 1.2 liters of toluene, it was left still overnight.

(2) Synthesis of cocatalyst carrier (A) 0.550 liter (1.10 mol) of diethylzinc in hexane (2.00 mol / liter) was added to the slurry obtained above and cooled to 5 ° C. A solution prepared by dissolving 105 g (0.570 mol) of pentafluorophenol in 173 ml of toluene was added dropwise thereto over 65 minutes. After completion of dropping, the mixture was stirred at 5 ° C. for 1 hour. Then, it heated at 40 degreeC and stirred for 1 hour. After the temperature was adjusted to 5 ° C. with an ice bath, 14.9 g (0.828 mol) of H ₂ O was added dropwise over 90 minutes. After completion of dropping, the mixture was stirred at 5 ° C. for 1.5 hours and at 40 ° C. for 2 hours. Then, it left still overnight at room temperature. Then, after stirring at 80 ° C. for 2 hours, the mixture is allowed to stand to settle the solid component, and when the interface between the precipitated solid component layer and the upper slurry portion is seen, the upper slurry portion is removed, and then the remaining liquid After filtering the components with a filter, 1.7 liters of toluene was added and stirred at 95 ° C. for 2 hours. Thereafter, the mixture was stirred four times with 1.7 liters of toluene at 95 ° C. and twice with 1.7 liters of hexane at room temperature, and then allowed to stand to precipitate the solid component. When the interface with the slurry portion was seen, the upper slurry portion was removed, and the remaining liquid component was then filtered through a filter. Thereafter, the solid component was dried at room temperature under reduced pressure for 3 hours to obtain 0.39 kg of a promoter support (A).
[Preparation of pre-polymerization catalyst])
100 liters of butane containing triisobutylaluminum at a concentration of 2.5 mmol / liter, 0.5 liter of 1-butene, and 8 liters of hydrogen at room temperature and normal pressure were charged in an autoclave with a stirrer having an internal volume of 210 liters that had been purged with nitrogen in advance. Thereafter, the temperature of the autoclave was raised to 23 ° C. Further, ethylene was charged for 0.2 MPa at a gas phase pressure in the autoclave, and after the system was stabilized, 250 mmol of triisobutylaluminum, 30 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide, and then the above promoter support (A) 0.20 kg was charged to initiate polymerization. While raising the temperature to 30 ° C. and supplying ethylene and hydrogen continuously, prepolymerization was carried out at 30 ° C. for a total of 4 hours. After the polymerization was completed, ethylene, butane, hydrogen gas and the like were purged, and the remaining solid was vacuum-dried at room temperature, so that 58 g of ethylene / 1-butene copolymer was prepolymerized per 1 g of the promoter support (A). A prepolymerized catalyst component was obtained.

[polymerization]
Using the prepolymerization catalyst component obtained above, copolymerization of ethylene and 1-hexene was carried out in a continuous fluidized bed gas phase polymerization apparatus. The polymerization conditions were a temperature of 85 ° C., a total pressure of 2 MPa, a gas linear velocity of 0.24 m / sec, a hydrogen molar ratio to ethylene of 0.8%, and a 1-hexene molar ratio to ethylene of 1.5%. In order to maintain a constant, ethylene, 1-hexene and hydrogen were continuously supplied. Ethylene / 1-hexene copolymerization with an average polymerization time of 4 hr and a production efficiency of 23 kg / hr so that the prepolymerized catalyst component and triisobutylaluminum are continuously supplied and the total powder weight of the fluidized bed is maintained at 80 kg. I got a powder. The ethylene / 1-hexene copolymer powder thus obtained was blended with 1000 ppm calcium stearate and 1800 ppm Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.), Tanabe Plastics Co., Ltd., 40 mmφ, L / D = 28. Then, an ethylene / 1-hexene copolymer was obtained by granulation with a full flight screw single screw extruder under the conditions of 150 ° C. and screw rotation speed of 80 rpm. The obtained ethylene / 1-hexene copolymer exhibited physical property values and film appearance as shown in Table 1.

Example 2
[Preparation of prepolymerization catalyst]
In the same manner as in Example 1, a prepolymerized catalyst component in which 47 g of ethylene / 1-butene copolymer was prepolymerized per 1 g of the promoter support (A) was obtained.
[polymerization]
Using the prepolymerized catalyst component obtained above, ethylene and 1-hexene were copolymerized in a continuous fluidized bed gas phase polymerization apparatus in the same manner as in Example 1. The obtained ethylene / 1-hexene copolymer exhibited physical property values and film appearance as shown in Table 1.

Example 3
Using a prepolymerized catalyst component in which 13 g of ethylene / 1-butene copolymer was prepolymerized per 1 g of the cocatalyst support (A), the temperature was 75 ° C., the molar ratio of hydrogen to ethylene was 1.55%, and 1-hexene mol to ethylene. The copolymerization of ethylene and 1-hexene was carried out in the same manner as in Example 1 except that the copolymerization was carried out with the ratio changed to 1.0% to obtain an ethylene / 1-hexene copolymer powder.

[Kneading]
The ethylene / 1-hexene copolymer powder obtained above was blended with 1000 ppm of calcium stearate and 1800 ppm of Sumilizer GP (manufactured by Sumitomo Chemical Co., Ltd.) using an LCM100 extruder manufactured by Kobe Steel, Ltd., at a feed rate of 350 kg / An ethylene / 1-hexene copolymer was obtained by granulation under the conditions of hr, screw rotation speed 450 rpm, gate opening 4.2 mm, gear pump suction pressure 0.2 MPa, and resin temperature 200-230 ° C. The obtained ethylene polymer exhibited physical property values and film extrusion moldability as shown in Table 1.

Reference example 4
Using the same prepolymerization catalyst component as used in Example 3, the hydrogen molar ratio to ethylene was 1.9%, the 1-hexene molar ratio to ethylene was 0.28%, and the molar ratio to ethylene was 3.1%. An ethylene / 1-butene / 1-hexene copolymer was obtained in the same manner as in Example 3 except that copolymerization was carried out by changing to using butene together. The obtained ethylene / 1-butene / 1-hexene copolymer exhibited physical property values and film extrusion moldability as shown in Table 1.

Reference Example 5
Using a prepolymerized catalyst component in which 34 g of ethylene / 1-butene copolymer is prepolymerized per 1 g of the co-catalyst support (A), the temperature is 85 ° C., the hydrogen molar ratio to ethylene is 0.8%, instead of 1-hexene. In the same manner as in Example 3, except that 4-methyl-1-pentene was used and only the 4-methyl-1-pentene molar ratio to ethylene was changed to 2.6%, copolymerization was carried out. A methyl-1-pentene copolymer was obtained. The obtained ethylene-4-methyl-1-pentene copolymer exhibited physical property values and film extrusion moldability as shown in Table 1.

Comparative Examples 1-3
[Catalyst component]
Preparation of cocatalyst support (A) In a 5-liter four-necked flask purged with nitrogen, 1.5 liters of tetrahydrofuran and 1.35 liters (2.7 mol) of diethylzinc hexane solution (2 mol / liter) were placed at 5 ° C. Cooled to. A solution prepared by dissolving 0.2 kg (1 mol) of pentafluorophenol in 500 ml of tetrahydrofuran was added dropwise thereto over 60 minutes. After completion of dropping, the mixture was stirred at 5 ° C. for 60 minutes, and the temperature was raised to 45 ° C. over 28 minutes, followed by stirring for 60 minutes. Thereafter, the temperature was lowered to 20 ° C. in an ice bath, and 45 g (2.5 mol) of water was added dropwise over 90 minutes. Thereafter, the mixture was stirred at 20 ° C. for 60 minutes, heated to 45 ° C. over 24 minutes, and stirred for 60 minutes. Thereafter, the solvent was distilled off under reduced pressure for 120 minutes while raising the temperature from 20 ° C. to 50 ° C., and then dried under reduced pressure for 8 hours at 120 ° C. As a result, 0.43 kg of a solid product was obtained.
0.43 kg of the above solid product and 3 liters of tetrahydrofuran were placed in a 5-liter four-necked flask purged with nitrogen and stirred. Thereto was added 0.33 kg of silica (Sypolol 948 manufactured by Devison; average particle size = 61 μm; pore volume = 1.61 ml / g; specific surface area = 296 m ² / g) heated at 300 ° C. under nitrogen flow. After heating to 40 ° C. and stirring for 2 hours, the mixture was allowed to stand to settle the solid component, and when the interface between the precipitated solid component layer and the upper slurry portion was seen, the upper slurry portion was removed. . As a washing operation, 3 liters of tetrahydrofuran was added thereto, and after stirring, the mixture was allowed to stand to settle the solid component. Similarly, when the interface was seen, the upper slurry portion was removed. The above washing operation was repeated 5 times in total. Thereafter, drying was performed at 120 ° C. under reduced pressure for 8 hours to obtain 0.52 kg of a promoter support (A).
[Preparation of prepolymerization catalyst]
After charging 80 liters of butane containing triisobutylaluminum at a concentration of 2.5 mmol / liter and 28 liters of hydrogen at normal temperature and pressure into an autoclave with a stirrer with an internal volume of 210 liters that was previously purged with nitrogen, the autoclave was heated to 40 ° C. The temperature rose. Further, ethylene was charged for 0.3 MPa at the gas phase pressure in the autoclave, and after the system was stabilized, 200 mmol of triisobutylaluminum, 28 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide, and then in the above comparative example Polymerization was started by adding 0.2 kg of the obtained promoter support (A). While raising the temperature from 40 ° C. to 50 ° C. and continuously supplying ethylene and hydrogen, preliminary polymerization was carried out for a total of 4 hours. After completion of the polymerization, after purging ethylene, butane and hydrogen gas, the solvent is filtered, and the resulting solid is vacuum-dried at room temperature, so that 60 g of polyethylene per 1 g of the promoter support (A) is prepolymerized. A polymerization catalyst component was obtained.

[polymerization]
Using the prepolymerized catalyst component obtained as described above, in the same manner as in Example 1, the hydrogen molar ratio to ethylene during polymerization was in the range of 0.3 to 0.5%, and the 1-hexene molar ratio to ethylene was 1. An ethylene-1-hexene copolymer having a different MFR was obtained by adjusting the content in the range of 0.8 to 2.0% and carrying out copolymerization of ethylene and 1-hexene in a continuous fluidized bed gas phase polymerization apparatus. The obtained ethylene-1-hexene copolymer exhibited physical property values and film appearance as shown in Table 1. From this result, a relational expression of log A, characteristic relaxation time τ, and MFR of an ethylene-α-olefin copolymer excellent in normal moldability was obtained. Moreover, in the ethylene-alpha-olefin copolymer of Comparative Examples 1-3, it turns out that although the external appearance of an extrusion molded product improves with a MFR raise, on the other hand, a fall of impact strength or a melt tension is caused.

Comparative Example 4
[Catalyst component]
A 5-liter four-necked flask purged with nitrogen was charged with 1.5 liters of tetrahydrofuran and 1330 ml (2.7 mol) of diethylzinc in hexane (2 mol / liter) and cooled to 5 ° C. or lower. A solution prepared by dissolving 0.2 kg (1.1 mol) of pentafluorophenol in 340 ml of tetrahydrofuran was added dropwise thereto over 60 minutes. After completion of dropping, the mixture was stirred at 5 ° C. for 1 hour and at 45 ° C. for 1 hour. Thereafter, the temperature was lowered to 20 ° C. in an ice bath, and 45 g (2.5 mol) of water was added dropwise over 90 minutes. As a result, the inside of the flask became a yellowish white slurry. After completion of dropping, the mixture was stirred for 1 hour, heated to 45 ° C., and further stirred for 1 hour. After allowing to stand overnight at room temperature, the liquid and solid materials were separated into nitrogen-substituted flasks, volatile components were distilled off, and drying was performed at 120 ° C. under reduced pressure for 8 hours. As a result, 0.20 kg of a solid product derived from a liquid and 0.23 kg of a solid product derived from a solid were obtained.
Silica (Sypolol 948, manufactured by Debison Co., Ltd.) was heated in a nitrogen-substituted 2-liter four-necked flask with 0.20 kg of the solid product derived from the above synthesis, 1.4 liters of tetrahydrofuran, and 300 ° C. under nitrogen flow. Pore volume = 1.61 ml / g; specific surface area = 306 m ² / g, average particle size = 59 µm) 0.14 kg was added and stirred at 40 ° C for 2 hours. After the silica-derived component was precipitated and the upper slurry component was removed, the remaining liquid part was removed with a glass filter. After adding 1.4 liters of tetrahydrofuran to this and stirring, the silica-derived component was allowed to settle, and after removing the upper layer slurry component, the remaining liquid part was removed with a glass filter. The above washing operation was repeated 5 times in total. Thereafter, drying was performed at 120 ° C. under reduced pressure for 8 hours to obtain 0.27 kg of a fluid promoter support (A).
[Preparation of prepolymerization catalyst]
After charging 100 liters of butane containing triisobutylaluminum at a concentration of 2.5 mmol / liter and 100 liters of hydrogen at room temperature and normal pressure into an autoclave with a stirrer with an internal volume of 210 liters that had been purged with nitrogen in advance, the autoclave was heated to 40 ° C. The temperature rose. Further, ethylene was charged for 0.2 MPa at the gas phase pressure in the autoclave, and after the system was stabilized, 200 mmol of triisobutylaluminum, 36 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide, and then Comparative Example 4 above. 0.25 kg of the cocatalyst carrier (A) obtained in (1) was added to initiate polymerization. While raising the temperature from 40 ° C. to 50 ° C. and continuously supplying ethylene and hydrogen, preliminary polymerization was carried out for a total of 4 hours. After completion of the polymerization, after purging ethylene, butane, and hydrogen gas, the solvent was filtered, and the resulting solid was vacuum-dried at room temperature, so that 39 g of polyethylene was prepolymerized per 1 g of the promoter support (A). A polymerization catalyst component was obtained.

[polymerization]
Using the prepolymerization catalyst component obtained above, in the same manner as in Example 1, a continuous flow was performed under the conditions of 0.2% hydrogen molar ratio to ethylene during polymerization and 1-hexene molar ratio to ethylene 1.9%. Copolymerization of ethylene and 1-hexene was carried out in a bed gas phase polymerization apparatus. As shown in Table 1, the relationship between log A and MFR of the obtained ethylene-1-hexene copolymer deviated greatly from the formula (3). The film haze value was high, and the appearance of the extruded product was extremely deteriorated among ethylene copolymers having the same MFR.

Comparative Example 5
[Catalyst component]
A SUS reactor having an internal volume of 180 liters equipped with a stirrer and a jacket was purged with nitrogen, and then heat-treated at 300 ° C. under a nitrogen flow (Sypolol 948 manufactured by Devison; pore volume = 1.65 ml / g; specific surface area = 9.7 kg of 298 m ² / g, average particle diameter = 58 μm) and 100 liters of toluene were added. After cooling to 2 ° C, 23.3 kg (75.9 mol per Al) of PMAO in toluene (PMAO-s manufactured by Tosoh Finechem) was added dropwise over 62 minutes. After completion of dropping, the mixture was stirred at 5 ° C for 30 minutes, heated to 95 ° C over 2 hours, and stirred at 95 ° C for 4 hours. Thereafter, the temperature was lowered to 40 ° C., and the mixture was transferred to an SUS reactor having an internal volume of 180 liters having a nitrogen-substituted stirrer and jacket. The silica-derived component was allowed to settle for 50 minutes, and the upper layer slurry component was removed. Then, after adding 100 liters of toluene and stirring for 10 minutes, it was made to settle for about 45 minutes and the slurry component of the upper layer was removed. The above washing operation was repeated a total of 3 times. Next, the slurry was transferred to a SUS filter having an internal volume of 430 liters, which had a nitrogen-substituted filter with 120 liters of toluene, a stirrer, and a jacket. The mixture was stirred for 10 minutes and filtered, 100 liters of toluene was added, and the mixture was stirred again for 10 minutes and filtered. Further, 100 liters of hexane was added and stirred for 10 minutes, followed by filtration. This washing operation was repeated twice in total. In 70 liters of hexane, the slurry was transferred to a SUS dryer having an internal volume of 210 liters equipped with a nitrogen-substituted stirrer and jacket. Subsequently, 12.6 kg of catalyst components (S) were obtained by carrying out nitrogen circulation drying at a jacket temperature of 80 ° C. for 7.5 hours.
[Preparation of prepolymerization catalyst]
After charging 120 liters of butane containing triisobutylaluminum at a concentration of 2.5 mmol / liter and 40 liters of hydrogen at room temperature and normal pressure into an autoclave with a stirrer with an internal volume of 210 liters that had been previously purged with nitrogen, the autoclave was heated to 47 ° C. The temperature rose. Further, ethylene was charged for 0.3 MPa at the gas phase pressure in the autoclave, and after the system was stabilized, 300 mmol of triisobutylaluminum, 15 mmol of racemic-ethylenebis (1-indenyl) zirconium dichloride, and then in Comparative Example 5 above 0.25 kg of the obtained catalyst component (S) was added to initiate polymerization, and preliminary polymerization was carried out for a total of 4 hours while continuously supplying ethylene and hydrogen. After the polymerization was completed, ethylene, butane, and hydrogen gas were purged, and the resulting solid was vacuum dried at room temperature to obtain a prepolymerized catalyst component in which 33 g of polyethylene was prepolymerized per 1 g of the catalyst component (S).

[polymerization]
Using the prepolymerization catalyst component obtained above, in the same manner as in Example 1, a continuous flow was performed under the conditions of 0.15% hydrogen molar ratio to ethylene during polymerization and 1-hexene molar ratio to 1.8% ethylene. Copolymerization of ethylene and 1-hexene was carried out in a bed gas phase polymerization apparatus.
The relationship between logA and MFR of the ethylene-1-hexene copolymer thus obtained showed the same relationship as Comparative Examples 1 to 3. The obtained film was not only in a range in which the haze value was satisfactory, but also had many fish eyes and the appearance of the extruded product was extremely deteriorated.

  As shown in Table 1, the ethylene-α-olefin copolymer of the present invention is excellent in the balance of molding processability represented by melt tension and mechanical strength represented by impact strength, and the appearance of the extruded product. I understand that

Claims (1)

An ethylene-α-olefin copolymer comprising a structural unit derived from ethylene and a structural unit derived from an α-olefin having 4 to 20 carbon atoms, wherein the melt flow rate (MFR; unit is g / 10 minutes) Is 1.65 or more and 2.18 or less, melt tension (MT; unit is cN) at 190 ° C. is 2.9 or more and 3.3 or less, and molecular weight distribution (Mw / Mn) is A film obtained by inflation molding an ethylene-α-olefin copolymer having a 9.2 to 16.6 SR and an SR of 1.28 to 1.45, and having a haze (unit: 30 μm) %) Is 6.3 or more and 9.1 or less, and the impact strength (TI; unit is kJ / m ² ) is 820 or more and 950 or less .