JP2013151637A - Resin for coating steel, and the steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin for coating steel with little variation of impact strength thereof at low temperature and steel coated with the resin for coating steel.SOLUTION: A resin for coating steel is composed of an ethylene-α-olefin copolymer which has: a monomer unit based on ethylene and a monomer unit based on a 3-20C α-olefin; a density of 860-930 kg/m; a melt flow rate (MFR) of 0.01-10 g/10 min; molecular weight distribution (Mw/Mn) which is a ratio of weight average molecular weight to number average molecular weight, of 4.5-10; an activation energy (Ea) of flow of 40-100 kJ/mol; a long chain branching amount measured by NMR of 0.29-0.50 pieces per the number of carbon atoms of 1,000; and g* defined by following formula (I) of 0.76-0.88. g*=[η]/([η]×g*)...(I).

Description

  The present invention relates to a steel coating resin composed of an ethylene-α-olefin copolymer and a steel coated with the steel coating resin.

  Steel pipes used for transporting natural gas, crude oil, and the like, and protecting and installing communication cables and the like are covered with a polyolefin-based resin for corrosion protection of the steel material. Since these steel pipes are sometimes used in cold districts, for example, Patent Documents 1 to 3 disclose ethylene-α-olefin copolymers for the purpose of improving tensile elongation at break and impact resistance at low temperatures. A steel coating made of a polymer is described.

JP-A-7-62164 JP-A-8-81522 JP 2005-281543 A

However, steel coatings made of conventional ethylene-α-olefin copolymers have variations in impact strength at low temperatures, and improvements have been demanded.
Under such circumstances, the problem to be solved by the present invention is to provide a steel coating resin having a small variation in impact strength at low temperatures and a steel material coated with the steel coating resin.

That is, the present invention has a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, a density of 860 to 930 kg / m ³ , and a melt flow rate (MFR). ) Is 0.01 to 10 g / 10 min, the molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight to the number average molecular weight, is 4.5 to 10, and the flow activation energy (Ea) is 40. -100 kJ / mol, the amount of long chain branching measured by NMR is 0.29 to 0.50 per 1000 carbon atoms, and g * defined by the following formula (I) is 0.76 to 0 It is related to a steel coating resin made of an ethylene-α-olefin copolymer of .88.
g * = [η] / ([η] _GPC × g _SCB *) (I)
[Wherein [η] represents the intrinsic viscosity (unit: dl / g) of the ethylene-α-olefin copolymer, and is a value defined by the following formula (I-I). [Η] _GPC is a value defined by the following formula (I-II). g _SCB * is a value defined by the following formula (I-III).
[Η] = 23.3 × log (ηrel) (II)
(In the formula, ηrel represents the relative viscosity of the ethylene-α-olefin copolymer.)
[Η] _GPC = 0.00046 × Mv ^0.725 (I-II)
(In the formula, Mv represents the viscosity average molecular weight of the ethylene-α-olefin copolymer.)
g _SCB * = (1-A) ^1.725 (I-III)
(In the formula, A is a value defined by the following formula (IV).)
A = ((12n + 2n + 1) * y) / ((1000-2y-2) * 14 + (y + 2) * 15 + 13y) (IV)
(In the formula, n represents the number of short-chain branched carbon atoms derived from the monomer unit based on the α-olefin of the ethylene-α-olefin copolymer, and y is a short number per 1000 carbon atoms. Represents the amount of chain branching.)]

  According to the present invention, it is possible to provide a steel material coating resin with small variations in impact strength at low temperatures and a steel material coated with the steel material coating resin.

About the ethylene-alpha-olefin copolymer of Examples 1-6 and Comparative Examples 1-3, the value of long-chain branching amount _NLCB (pieces / 1000C) was plotted with respect to the value of MFR (g / 10min). FIG. It is the figure which showed the melting curve obtained by the differential scanning calorimetry of the ethylene-alpha-olefin copolymer of Example 1 and Comparative Example 3. The figure which plotted the value of characteristic relaxation time (tau) ₀ (s ^<-1 >) with respect to the value of MFR (g / 10min) about the ethylene-alpha-olefin copolymer of Examples 1-6 and Comparative Examples 1-3. It is. For the ethylene-α-olefin copolymers of Examples 1-6 and Comparative Examples 1-3, the value of oligomer amount ΣCn; n = 12-18 (ppm) is plotted against the value of MFR (g / 10 min). FIG. It is the figure which plotted the value of HH110 (%) with respect to the value of a bending elastic modulus (MPa) about the ethylene-alpha-olefin copolymer of Examples 1-6 and Comparative Examples 1-3.

  The ethylene-α-olefin copolymer used in the present invention is an ethylene-α-olefin copolymer having a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms. It is. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 4-methyl-1-pentene, 4 -Methyl- 1-hexene etc. are mention | raise | lifted and these may be used independently and 2 or more types may be used together. The α-olefin is preferably 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene, more preferably 1-hexene, 4-methyl-1-pentene and 1-octene. .

  The ethylene-α-olefin copolymer used in the present invention includes, in addition to the above-described monomer units based on ethylene and monomer units based on α-olefins having 3 to 20 carbon atoms, as required. It may have a monomer unit based on the monomer. 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 content of the monomer unit based on ethylene in the ethylene-α-olefin copolymer used in the present invention is usually 50 to 100% based on the total weight (100% by weight) of the ethylene-α-olefin copolymer. 99.5% by weight. The content of the monomer unit based on the α-olefin is usually 0.5 to 50% by weight with respect to the total weight (100% by weight) of the ethylene-α-olefin copolymer.

  The ethylene-α-olefin copolymer used in the present invention is preferably a copolymer having a monomer unit based on ethylene and a monomer unit based on an α-olefin having 4 to 20 carbon atoms. More preferably, it is a copolymer having a monomer unit based on ethylene and a monomer unit based on an α-olefin having 5 to 20 carbon atoms, and more preferably a monomer unit based on ethylene It is a copolymer having a monomer unit based on an α-olefin having 6 to 8 carbon atoms.

  Examples of the ethylene-α-olefin copolymer used in the present invention include an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, an ethylene-4-methyl-1-pentene copolymer, and ethylene. -1-octene copolymer, ethylene-1-butene-1-hexene copolymer, ethylene-1-butene-4-methyl-1-pentene copolymer, ethylene-1-butene-1-octene copolymer , Ethylene-1-hexene-1-octene copolymer, etc., preferably ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, ethylene-1-octene copolymer. Ethylene-1-butene-1-hexene copolymer, ethylene-1-butene-1-octene copolymer, ethylene-1-hexene-1-octene copolymer, Ri is preferably ethylene-1-hexene copolymer, ethylene-4-methyl-1-pentene copolymer, an ethylene-1-octene copolymer.

The density of the ethylene-α-olefin copolymer used in the present invention (hereinafter sometimes referred to as “d”) is 860 to 930 kg / m ³ . From the viewpoint of increasing the low temperature impact strength of the coating portion made of an ethylene-α-olefin copolymer, it is preferably 928 kg / m ³ or less, more preferably 927 kg / m ³ or less, and further preferably 926 kg / m ³ or less. It is. Further, from the viewpoint of enhancing the solvent resistance and heat resistance of the coating portion made of an ethylene-α-olefin copolymer, it is preferably 870 kg / m ³ or more, more preferably 880 kg / m ³ or more, and still more preferably. It is 890 kg / m ³ or more, particularly preferably 900 kg / m ³ or more. The density is measured according to the method defined in Method A of JIS K7112-1980 after annealing described in JIS K6760-1995. Moreover, the density of an ethylene-alpha-olefin copolymer can be changed with content of the monomer unit based on ethylene in an ethylene-alpha-olefin copolymer.

  The melt flow rate (hereinafter sometimes referred to as “MFR”) of the ethylene-α-olefin copolymer used in the present invention is 0.01 to 10 g / 10 min. The melt flow rate is preferably 0.05 g / 10 min or more, more preferably 0.1 g / 10 min or more, from the viewpoint of reducing the extrusion load during molding. From the viewpoint of improving impact strength and solvent resistance, the melt flow rate is preferably 5 g / 10 min or less, more preferably 2 g / 10 min or less, and further preferably 1 g / 10 min or less. The melt flow rate is a value measured by Method A under the conditions of a temperature of 190 ° C. and a load of 21.18 N in the method defined in JIS K7210-1995. Further, the melt flow rate of the ethylene-α-olefin copolymer can be changed by, for example, the hydrogen concentration or the polymerization temperature in the production method described later. When the hydrogen concentration or the polymerization temperature is increased, the ethylene-α-olefin copolymer is changed. The melt flow rate of the copolymer is increased.

  The weight average molecular weight (hereinafter sometimes referred to as “Mw”) and the number average molecular weight (hereinafter sometimes referred to as “Mn”) of the ethylene-α-olefin copolymer used in the present invention. The molecular weight distribution (hereinafter sometimes referred to as “Mw / Mn”) is 4.5 to 10. Mw / Mn is preferably 4.7 or more, more preferably 4.9 or more, and further preferably, from the viewpoint of reducing the extrusion load during molding and improving the thickness uniformity of the coating resin portion. Is 5.1 or more, more preferably 5.3 or more. Mw / Mn is preferably 9.0 or less, more preferably 8.5 or less, and still more preferably, from the viewpoint of improving the impact strength and solvent resistance of the coating portion made of an ethylene-α-olefin copolymer. Is 8 or less, particularly preferably 7.5 or less, and most preferably 7.0 or less. The Mw / Mn is determined by measuring the number average molecular weight (Mn) and the weight average molecular weight (Mw) by gel permeation chromatography (GPC) method and dividing Mw by Mn. The Mw / Mn can be changed by, for example, the hydrogen concentration or the polymerization temperature in the production method described later. When the hydrogen concentration or the polymerization temperature is increased, the Mw / Mn of the ethylene-α-olefin copolymer is increased. growing.

  The flow activation energy of the ethylene-α-olefin copolymer used in the present invention (hereinafter sometimes referred to as “Ea”) reduces the extrusion load during the molding process, and the thickness of the coating resin portion. From the viewpoint of improving the uniformity of the film, it is 40 kJ / mol to 100 kJ / mol. From the viewpoint of fluidity, Ea of the ethylene-α-olefin copolymer of the present invention is preferably 45 kJ / mol or more, more preferably 55 kJ / mol or more, further preferably 60 kJ / mol or more, Particularly preferably, it is 65 kJ / mol or more. Moreover, from the viewpoint that the viscosity does not decrease too much even at a high temperature and the molding process is easy, Ea of the ethylene-α-olefin copolymer of the present invention is preferably 90 kJ / mol or less. In the production method described later, the flow activation energy can be changed, for example, depending on polymerization conditions such as hydrogen concentration, organoaluminum compound concentration, ethylene pressure, and polymerization temperature.

The activation energy (Ea) of the flow is dependent on the angular frequency (unit: rad / second) dependence of the melt complex viscosity (unit: Pa · second) at 190 ° C. based on the temperature-time superposition principle. It is a numerical value calculated by the Arrhenius type equation from the shift factor (a _T ) when creating the master curve shown, and is a value obtained by the method shown below. That is, the melt complex viscosity-angular frequency curve of the ethylene-α-olefin copolymer at temperatures of 130 ° C., 150 ° C., 170 ° C. and 190 ° C. (T, unit: ° C.) The unit of the angular frequency is rad / sec.), Based on the temperature-time superposition principle, for each melt complex viscosity-angular frequency curve at each temperature (T), The shift factor (a _T ) at each temperature (T) obtained when superposed on the melt complex viscosity-angular frequency curve of the coalescence is obtained, and each temperature (T) and the shift factor at each temperature ( _T ) are obtained. From (a _T ), a linear approximate expression (formula (II) below) of [ln (a _T )] and [1 / (T + 273.16)] is calculated by the method of least squares. Next, Ea is obtained from the slope m of the linear expression and the following expression (III).
ln (a _T ) = m (1 / (T + 273.16)) + n (II)
Ea = | 0.008314 × m | (III)
a _T : Shift factor Ea: Activation energy of flow (unit: kJ / mol)
T: Temperature (unit: ° C)
For the calculation, commercially available calculation software may be used. As the calculation software, Rheos V. manufactured by Rheometrics is used. 4.4.4.
The shift factor (a _T ) is obtained by moving the logarithmic curve of the melt complex viscosity-angular frequency at each temperature (T) in the log (Y) = − log (X) axis direction (however, the Y axis Is the complex viscosity of the melt, and the X axis is the angular frequency.), And the amount of movement when superposed on the melt complex viscosity-angular frequency curve at 190 ° C., in the superposition, melting at each temperature (T) The logarithmic curve of complex viscosity-angular frequency shifts the angular frequency by a _T times and the melt complex viscosity by 1 / a _T times for each curve. Moreover, the correlation coefficient when calculating | requiring (II) Formula by the least squares method from the value of 4 points | pieces, 130 degreeC, 150 degreeC, 170 degreeC, and 190 degreeC is usually 0.99 or more.

  The melt complex viscosity-angular frequency curve is measured using a viscoelasticity measuring device (for example, Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics), and usually geometry: parallel plate, plate diameter: 25 mm, plate interval: 1. It is performed under the conditions of 5 to 2 mm, strain: 5%, angular frequency: 0.1 to 100 rad / sec. The measurement is performed in a nitrogen atmosphere, and it is preferable that an appropriate amount (for example, 1000 ppm) of an antioxidant is added to the measurement sample in advance.

The long chain branching amount (LCB amount; hereinafter sometimes referred to as “N _LCB ”) measured by NMR of the ethylene-α-olefin copolymer used in the present invention is 0.29 to 1000 carbon atoms. 0.50. The amount of LCB per 1000 carbon atoms (N _LCB ) is preferably 0.30 or more, more preferably 0.31 or more, further preferably 0.32 or more from the viewpoint of improving workability. Particularly preferred is 0.33 or more, and most preferred is 0.34 or more. Moreover, from a viewpoint of raising mechanical strength, Preferably it is 0.45 or less, More preferably, it is 0.42 or less. In the production method described later, the amount of LCB can be changed, for example, depending on polymerization conditions such as hydrogen concentration, organoaluminum compound concentration, ethylene pressure, polymerization temperature, and the like.

The amount of LCB (N _LCB ) is determined by the carbon nuclear magnetic resonance ( ¹³ C-NMR) method, the carbon nuclear magnetic resonance ( ¹³ C-NMR) spectrum of the polymer under the measurement conditions described later, and determined by the calculation method described later. The number of long chain branches per 1000 carbon atoms in the polymer.

LCB amount (N _LCB ) measurement condition device: AVANCE 600 manufactured by Bruker
Measurement probe: 10 mm cryoprobe Measurement solvent: 1,2-dichlorobenzene / 1,2-dichlorobenzene-d4
= 75/25 (volume ratio) mixed solution measurement temperature: 130 ° C.
Measurement method: proton decoupling method Pulse width: 45 degrees Pulse repetition time: 4 seconds Measurement standard: Tetramethylsilane window function: Exponential or Gaussian integration number: 2500

Calculation method of long chain branching amount (LCB amount) In NMR spectrum in which window function is processed with Gaussian, carbon atom number is 7 or more when sum of peak areas of all peaks having peak top at 5 to 50 ppm is 1000 The peak area of the peak derived from methine carbon to which the branches are bonded is defined as the amount of long-chain branching (the number of branches having 7 or more carbon atoms). Under these measurement conditions, the peak area of a peak having a peak top in the vicinity of 38.22 to 38.27 ppm when the sum of peak areas of all peaks having a peak top at 5 to 50 ppm is 1000 is a long chain branch. Amount (number of branches having 7 or more carbon atoms). The peak area of the peak was defined as the area of the signal in the range from the chemical shift of the valley with the adjacent peak on the high magnetic field side to the chemical shift of the valley with the adjacent peak on the low magnetic field side. In this measurement condition, a branch having 7 or more carbon atoms is a long chain branch. Therefore, a branch having 6 or less carbon atoms is not regarded as a long chain branch. For example, a hexyl branch (branch having 6 carbon atoms) derived from 1-octene of an ethylene-1-octene copolymer is not regarded as a long chain branch. In the measurement of the ethylene-1-octene copolymer, the position of the peak top of the peak derived from the methine carbon bonded with the hexyl branch is 38.21 ppm, and is not included in the peak used for calculating the LCB amount. .

  G * of the ethylene-α-olefin copolymer used in the present invention is 0.76 to 0.88. g * is an index representing the degree of contraction of a molecule in a solution caused by long chain branching. If the amount containing long chain branching is large, the molecule is more easily contracted, and g * becomes smaller. From the viewpoint of imparting sufficient processing characteristics, particularly strain hardening characteristics, and improving processing stability and uniformity of the thickness of the coating resin portion, it is preferably 0.85 or less, more preferably 0.84 or less. Particularly preferred is 0.83 or less, and most preferred is 0.82 or less. Further, g * of the ethylene-α-olefin copolymer is preferably 0.77 or more, more preferably 0.78 or more, from the viewpoint of improving the mechanical strength of the coating resin portion. g * can be lowered, for example, by carrying out prepolymerization under suitable conditions.

g * is a value defined by the following formula (I) (g * was referred to the following document: Developments in Polymer Characterisation-4, JV. Dawkins, Ed., Applied Science, London, 1983, Chapter. I, “Characterization. Of. Long Chain Branching in Polymers,” by Th. G. Scholte.
g * = [η] / ([η] _GPC × g _SCB *) (I)
[Wherein [η] represents the intrinsic viscosity (unit: dl / g) of the ethylene-α-olefin copolymer, and is a value defined by the following formula (I-I). [Η] _GPC is a value defined by the following formula (I-II). g _SCB * is a value defined by the following formula (I-III).
[Η] = 23.3 × log (ηrel) (II)
(In the formula, ηrel represents the relative viscosity of the ethylene-α-olefin copolymer.)
[Η] _GPC = 0.00046 × Mv ^0.725 (I-II)
(In the formula, Mv represents the viscosity average molecular weight of the ethylene-α-olefin copolymer.)
g _SCB * = (1-A) ^1.725 (I-III)
(In the formula, A is a value defined by the following formula (IV).
A = ((12n + 2n + 1) * y) / ((1000-2y-2) * 14 + (y + 2) * 15 + 13y) (IV)
(In the formula, n represents the number of short-chain branched carbon atoms derived from the monomer unit based on the α-olefin of the ethylene-α-olefin copolymer, and y is a short number per 1000 carbon atoms. Represents the amount of chain branching.)]

[Η] _GPC is the intrinsic viscosity (unit: dl / g) of a polymer that is assumed to have the same molecular weight distribution as that of the ethylene-α-olefin copolymer and that the molecular chain is linear. Represents.
g _SCB * represents the contribution to g * produced by introducing short chain branching into the ethylene-α-olefin copolymer.
As the formula (I-II), the formula described in Journal of Polymer Science, 36, 130 (1959) pp. 287-294 by LH Tung was used.

  The relative viscosity (ηrel) of the ethylene-α-olefin copolymer was obtained by dissolving 100 mg of the olefin polymer at 135 ° C. in 100 ml of tetralin containing 0.5% by weight of butylhydroxytoluene (BHT) as a thermal degradation inhibitor. A solution is prepared, and is calculated from the falling time of the sample solution and a blank solution made of tetralin containing only 0.5% by weight of BHT as a thermal degradation inhibitor using an Ubbelohde viscometer.

で定義され、a＝０．７２５とした。 The viscosity-average molecular weight (Mv) of the ethylene-α-olefin copolymer is the following formula (I-IV)

And a = 0.725.

A in the formula (I-III) is a value defined by the following formula (IV). N in the formula (IV) represents the number of short-chain branched carbon atoms derived from the monomer unit based on the α-olefin of the ethylene-α-olefin copolymer (for example, butene as α-olefin). When used, n = 2, and when using hexene, n = 4), y represents the amount of short chain branching per 1000 carbon atoms, and is a value determined by NMR or infrared spectroscopy.
A = ((12n + 2n + 1) * y) / ((1000-2y-2) * 14 + (y + 2) * 15 + 13y) (IV)
When the ethylene-α-olefin copolymer has monomer units derived from different types of α-olefins, A is a value defined by the following formula (IV ′).
type of α- olefin as is m type, the number of carbon atoms of short chain branches derived from the monomer unit based on each α- olefin, respectively, n _{1, n 2,} and · · · n _m, the α- olefins from monomer unit based on the short-chain branching, y ₁ the short chain branching of several per 1000 carbon _atoms, y _2, ··· y _m, all short chain branching number per 1000 carbon atoms When the number is ytotal,
A = ((12n ₁ + 2n ₁ +1) × y ₁ ) + (12n ₂ + 2n ₂ +1) × y ₂ ) +
_{··· + (12n m + 2n m} +1) × y m)) / ((1000-2ytotal-2) ×
14+ (ytotal + 2) × 15 + 13ytotal) (IV ′)

The ethylene-α-olefin copolymer used in the present invention is based on the differential scanning calorimetry of the ethylene-α-olefin copolymer from the viewpoint of improving the heat resistance of the coating portion made of the ethylene-α-olefin copolymer. In the melting curve showing the relationship between the melting curve temperature and the heat flow, the melting peak shows a plurality of melting peaks in the range from 25 ° C. to 150 ° C., and the melting peak height (heat flow) is higher than the largest melting peak. It is preferable to show a melting peak different from the maximum melting peak.
Here, the melting peak means a point where the peak height (heat flow) shows a maximum value in the melting curve or an inflection point that satisfies the following conditions.
An arbitrary inflection point in the melting curve is defined as an inflection point (1), and the inflection point adjacent to the inflection point (1) is lower than the inflection point (1). When the inflection point (2) is an inflection point adjacent to the inflection point (1) and exists at a higher temperature than the inflection point (1), the inflection point (3) is changed. When the peak height (heat flow) of the inflection point (1) is larger than the straight line connecting the inflection point (2) and the inflection point (3), the inflection point (1) is set as the melting peak. Examples of the inflection points (1) to (3) are shown in the melting curve of Example 1 in FIG. The melting curve of Comparative Example 3 in FIG. 2 is an example in which only one melting peak exists in the range from 25 ° C. to 150 ° C.
The ethylene-α-olefin copolymer showing a melting peak different from the maximum melting peak at a temperature higher than the maximum melting peak having the largest peak height is the same density as the ethylene-α-olefin copolymer, It means that the ethylene-α-olefin copolymer having rigidity and having only one melting peak contains a component having high crystallinity. A component having high crystallinity can improve the moldability during melt molding and improve the heat resistance of the resulting coating resin part. In addition, the number of melting peaks can be changed by, for example, the organoaluminum compound concentration or the polymerization temperature in the production method described later. When the organoaluminum compound or the polymerization temperature is increased, the ethylene-α-olefin copolymer is increased. The secondary melting peak area increases.

  In addition, the melting curve of the ethylene-α-olefin copolymer is measured by using a differential scanning calorimeter (for example, a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer), for example, an aluminum pan in which about 10 mg of a sample is sealed. (1) held at 150 ° C. for 5 minutes, (2) lowered from 150 ° C. to 20 ° C. at 5 ° C./minute, (3) held at 20 ° C. for 2 minutes, and (4) 20 at 5 ° C./minute. It is obtained from the differential scanning calorimetry curve obtained in (4) by raising the temperature from 0 ° C. to the melting end temperature + about 20 ° C. (usually about 150 ° C.).

The characteristic relaxation time of the ethylene-α-olefin copolymer used in the present invention (hereinafter sometimes referred to as “τ ₀ ”) is used to coat the steel material with the ethylene-α-olefin copolymer of the present invention. From the viewpoint of improving the adhesion of the resin to the steel material and improving the adhesion between the resin portion and the steel material, the following (a-1) is preferable.
τ ₀ <3.8 × MFR ^−0.62 formula (a-1)
More preferably, the formula (a-2) is satisfied, further preferably the formula (a-3 is satisfied, particularly preferably the formula (a-4) is satisfied, and most preferably the formula (a-5) is satisfied. ) Is satisfied.
τ ₀ <3.7 × MFR ^−0.62 (a-2)
τ ₀ <3.6 × MFR ^−0.62 (a-3)
τ ₀ <3.5 × MFR ^−0.62 (a-4)
τ ₀ <3.4 × MFR ^−0.62 (a-5)

In general, it is known that the following formula is established for a polymer having sufficient entanglement.
τ ₀ = A · η ₀ formula (2)
Further, in FIG. 14 of Macromolecules, 33, 7489 (2000) (PM Wood-Adams et al.), In a metallocene polyethylene containing long chain branches, log-log plots of η ₀ and Mw can be expressed by straight lines. It is reported that this is a polyethylene containing long chain branches and the following formula η ₀ = B · Mw ^ε formula (3)
Strongly suggests that Substituting this equation (3) into equation (2), the following equation (4) can be derived.
τ ₀ = C · MFR ^ε formula (4)
In order to define the range of τ ₀ of the ethylene-α-olefin copolymer used in the present invention, the inequality of formula (a) was used.
τ ₀ <C ₁ · MFR ^ε1 formula (a)

The plot of τ ₀ and MFR in the example of the present invention was fitted by the equation (4) using Microsoft Excel. MFR and relaxation time of Examples 1-6 were used for fitting. In view of the accuracy of data, -0.62 was obtained as ε1. Also from the equation (a-1) is a inequalities multiplied by a constant a C ₁ in the following manner to obtain a formula (a-5).
To give formula (a-1) as the _{C 1} to 1.235 times the value of the resulting C from the fitting. To give formula (a-2) as a _{C 1} to 1.202 times the value of the resulting C from the fitting. To give formula (a-3) as a _{C 1} to 1.170 times the value of the resulting C from the fitting. The value of C obtained from the fitting is multiplied by 1.137 to obtain C ₁ as formula (a-4)
Got. The value of C obtained by fitting is multiplied by 1.105 to obtain C ₁ as the formula (a-5
)

Similarly, in order to define a preferable range of τ ₀ of the ethylene-α-olefin copolymer used in the present invention, the inequality of the formula (b) was used.
τ ₀ > C ₂ · MFR ^ε2 formula (b)

Τ ₀ of the ethylene-α-olefin copolymer used in the present invention is preferably the following from the viewpoint of preventing the molten resin from sagging when the steel is coated with the resin and making the coating resin portion thickness uniform. Relational expression (b-1)
τ ₀ > 1.5 × MFR ^−0.62 (b-1)
Is satisfied, more preferably the relational expression of the formula (b-2) is satisfied, and still more preferably the relational expression of the formula (b-3) is satisfied.
τ ₀ > 2.0 × MFR ^−0.62 (b-2)
τ ₀ > 2.5 × MFR ^−0.62 (b-3)

The plot of τ ₀ and MFR in the example of the present invention was fitted by the equation (4) using Microsoft Excel. MFR and relaxation time of Examples 1-6 were used for fitting. In view of the accuracy of the data, -0.62 was obtained as ε2. Also the following manner inequalities that constant multiple of C ₂ formula (b-1) was obtained formula (b-3).
And 0.478 times the value of the resulting C from the fitting as a _{C 2} Equation (b-1). And 0.650 times the value of the resulting C from the fitting as a _{C 2} Equation (b-2). And 0.812 times the value of the resulting C from the fitting as a _{C 2} Equation (b-3).

The characteristic relaxation time (τ ₀ ) is a numerical value related to the molecular weight of the ethylene-α-olefin copolymer and the length of the long chain branch (the number of carbon atoms of the long chain branch), and the molecular weight is small or the long chain branch When the is short, the characteristic relaxation time becomes a small value, and when the molecular weight is large or long chain branching is long, the characteristic relaxation time becomes a large value. In order to obtain a high melt tension and a high strain hardening property, it is necessary that a long chain branch having a sufficient amount or a sufficient length is introduced into the molecular chain, and preferably has a certain relaxation time or more. On the other hand, a polymer having a too long relaxation time has high strain hardening characteristics, but the take-up property of the molten resin with respect to the melt tension is deteriorated, that is, the balance between the melt tension and the take-up property is deteriorated. In the production method described later, the characteristic relaxation time can be changed, for example, depending on polymerization conditions such as hydrogen concentration, ethylene pressure, and polymerization temperature, and the characteristic relaxation time of the ethylene-α-olefin copolymer can be changed.

The characteristic relaxation time is calculated from a master curve showing the dependence of the melt complex viscosity (unit: Pa · second) at 190 ° C on the angular frequency (unit: rad / second), which is created based on the temperature-time superposition principle. It is a numerical value. Specifically, the melt complex viscosity-angular frequency curve of the ethylene-α-olefin copolymer at each temperature (T, unit: ° C.) at 130 ° C., 150 ° C., 170 ° C. and 190 ° C. (unit of melt complex viscosity is (Pa · sec, unit of angular frequency is rad / sec.) Is superposed on the melt complex viscosity-angular frequency curve at 190 ° C based on the temperature-time superposition principle to obtain a master curve. It is a value calculated by approximating the master curve by the following formula (5).
η = η ₀ / [1+ (τ ₀ × ω) ⁿ ] (5)
η: melt complex viscosity (unit: Pa · sec)
ω: angular frequency (unit: rad / sec)
τ ₀ : Characteristic relaxation time (unit: s ⁻¹ )
η ₀ : Constant determined for each ethylene-α-olefin copolymer (unit: Pa · second)
n: Constant determined for each ethylene-α-olefin copolymer The above calculation may use commercially available calculation software.
Rheos V. manufactured by hemetrics. 4.4.4.

The melt complex viscosity-angular frequency curve is measured using a viscoelasticity measuring device (for example, Rheometri
cs Rheometrics Mechanical Spectrometer
RMS-800 etc.), usually geometry: parallel plate, plate diameter:
25 mm, plate interval: 1.5-2 mm, strain: 5%, angular frequency: 0.1-10
It is performed under the condition of 0 rad / sec. Note that the measurement is performed in a nitrogen atmosphere, and it is preferable that an appropriate amount (for example, 1000 ppm) of an antioxidant is added to the measurement sample in advance.

  The melt flow rate ratio of the ethylene-α-olefin copolymer used in the present invention (hereinafter sometimes referred to as “MFRR”) is preferably 60 from the viewpoint of further reducing the extrusion load during molding. It is above, More preferably, it is 65 or more, More preferably, it is 70 or more. Moreover, from a viewpoint which raises the mechanical strength of the coating part which consists of an ethylene-alpha-olefin copolymer more, Preferably it is 150 or less, More preferably, it is 130 or less. The MFRR is a melt flow rate (hereinafter sometimes referred to as “H-MFR”) measured under conditions of a load of 211.82 N and a temperature of 190 ° C. in the method defined in JIS K7210-1995. In the method defined in JIS K7210-1995, it is a value divided by the melt flow rate (MFR) measured under conditions of a load of 21.18 N and a temperature of 190 ° C. In addition, MFRR can be changed by, for example, the hydrogen concentration in the production method described later. When the hydrogen concentration is increased, the MFRR of the ethylene-α-olefin copolymer is decreased.

  The ratio (Mz / Mw) of polystyrene-equivalent z-average molecular weight (Mz) and weight-average molecular weight (Mw) of the ethylene-α-olefin copolymer used in the present invention is 2.2 to 3.5. preferable. In order to obtain a coating portion composed of an ethylene-α-olefin copolymer having good mechanical strength, the Mz / Mw of the ethylene-α-olefin copolymer is preferably 3.0 or less, more preferably 2 .9 or less, more preferably 2.7 or less. Moreover, from a viewpoint of reducing the extrusion load at the time of a shaping | molding process more, Preferably it is 2.3 or more, More preferably, it is 2.4 or more.

The dynamic complex viscosity (η ^{* 100} , unit: Pa · sec) at a temperature of 190 ° C. and an angular frequency of 100 rad / sec of the ethylene-α-olefin copolymer used in the present invention is 1500 Pa from the viewpoint of enhancing the extrusion processability. -It is preferable that it is below second. It is preferably 1300 Pa · sec or less, more preferably 1200 Pa · sec or less, further preferably 1150 Pa · sec or less, and most preferably 1100 Pa · sec or less. Further, from the viewpoint of increasing mechanical strength, it is preferably 300 Pa · second or more, more preferably 400 Pa · second or more, and further preferably 500 Pa · second or more. The angular frequency of 100 rad / sec is an angular frequency close to the shear rate when an ethylene-α-olefin copolymer is processed with a general processing machine, and can be used as an index of workability.

  The melt tension at 190 ° C. of the ethylene-α-olefin copolymer used in the present invention is preferably 4 to 30 cN from the viewpoint of stably producing a coating resin portion having a uniform thickness. More preferably, it is 4.5 cN or more, More preferably, it is 4.7 cN or more, Especially preferably, it is 4.9 cN or more. Moreover, it is preferably 25 cN or less, more preferably 20 cN or less from the viewpoint of improving the adhesion of the resin to the steel material when coating the resin on the steel material and improving the adhesion between the resin portion and the steel material.

The amount of oligomer contained in the ethylene-α-olefin copolymer used in the present invention (hereinafter sometimes referred to as ΣCn; n = 12-18) is the cleanliness of the coating resin part, between the coating resin part and the steel material. Adhesive strength of steel, especially the viewpoint of suppressing the contamination of the adhesive surface between the steel and the coated resin part due to smoke generated during processing, and the transition of the various additives contained in the resin composition to the adhesive surface between the steel material and the coated resin part From the viewpoint of suppressing the following formula (c-1)
ΣCn; n = 12−18 <310 × ln (MFR) +1200 formula (c−1)
It is preferable to satisfy.
More preferably, the formula (c-2) is satisfied, and still more preferably the formula (c-3) is satisfied.
ΣCn; n = 12−18 <310 × ln (MFR) +1150 Formula (c-2)
ΣCn; n = 12−18 <310 × ln (MFR) +1000 formula (c-3)
Here, the oligomer means a hydrocarbon having 12 to 18 carbon atoms.

The amount of oligomer is affected by the concentration of hydrogen supplied during the polymerization of the ethylene-α-olefin copolymer. Similarly, the MFR value controlled by the hydrogen concentration during the polymerization and the ethylene-α-olefin copolymer Shows a certain relational expression (6). This is because, generally, the larger the MFR (the smaller the molecular weight), the greater the amount of oligomer.
ΣCn; n = 12−18 = D × ln (MFR) + E Formula (6)
Here, the amount of oligomer was converted from the gas chromatography detection peak area of hydrocarbons having 12 to 18 carbon atoms obtained under the measurement conditions described later to hydrocarbon concentration (ppm) of 18 carbon atoms. Value.
In order to define the preferable range of the oligomer amount of the ethylene-α-olefin copolymer used in the present invention, the inequality of the formula (c) was used.
ΣCn; n = 12−18 <D ₁ × ln (MFR) + E ₁ formula (c)

Fitting of the amount of oligomer and the MFR in the example of the present invention was performed by the formula (1) using Microsoft Excel. The MFR and oligomer amount of Examples 1 to 6 were used for fitting. Etc. In view of the accuracy of the data, to obtain a _{D 1} as 310. The yield of formula (c-3) from the formula (c-1) is a inequalities multiplied by a constant to E ₁ in the following manner.
The value of E obtained from the fitting was multiplied by 1.216 to obtain E ₁ to obtain formula (c-1). The value of E obtained from the fitting was multiplied by 1.165 to obtain E ₁ to obtain formula (c-2). Was obtained as _{E 1} a (c-3) the value of E obtained from the fitting 1.013 multiplied by.

  Preferably, the amount of oligomer (ΣCn; n = 12-18) contained in the ethylene-α-olefin copolymer used in the present invention is 1000 ppm or less.

The amount of oligomer (ΣCn; n = 12-18) contained in the ethylene-α-olefin copolymer used in the present invention can be measured using gas chromatography. The oligomer can be extracted by an ultrasonic method. The GC measurement device and each measurement condition are as follows.
GC measuring device manufactured by SHIMADZU GC-2010
DB-1 made by J & W
(Film thickness 0.15 μm, length 15 m, inner diameter 0.53 mm) Connection detector (FID) temperature 310 ° C.
Measurement column temperature After holding at 100 ° C. for 1 minute, the total of detection peak areas of hydrocarbons having 12 to 18 carbon atoms in the gas chromatogram chart obtained by raising the temperature to 310 ° C. at 10 ° C./min is the number of carbon atoms. Converted to a hydrocarbon concentration of 18 (ppm).

Method for Producing Ethylene-α-Olefin Copolymer As a method for producing the ethylene-α-olefin copolymer used in the present invention, for example, diethylzinc (hereinafter referred to as component (a)) and 3,4. , 5-trifluorophenol (hereinafter referred to as component (b)), water (hereinafter referred to as component (c)), and inorganic compound particles (hereinafter referred to as component (d)). A solid particulate promoter support (hereinafter referred to as component (A)) obtained by contact in a toluene solvent and two ligands having a cyclopentadienyl skeleton, and the two coordinations A metallocene complex (hereinafter referred to as “component (B)”) having a structure in which a child is bonded by a crosslinking group such as an alkylene group or a silylene group, and an organoaluminum compound (hereinafter referred to as “component (C)”) are used as catalyst components. Of the polymerization catalyst used Examples thereof include a method of copolymerizing ethylene and an α-olefin in the presence.

Component (d) is 1,1,1,3,3,3-hexamethyldisilazane (((CH ₃ ) ₃ Si) ₂ NH) (hereinafter referred to as component (e)) as necessary. You may carry out contact processing with.

  The inorganic compound particles of component (d) are preferably silica gel.

The amount of component (a), component (b), and component (c) used is not particularly limited, but the molar ratio of the amount of each component used is component (a): component (b): component (c) = 1: When the molar ratio of y: z is used, it is preferable that y and z substantially satisfy the following formula (1).
0.5 <y + 2z <5 (1)
In the above formula (1), y is preferably a number of 0.5 to 4, more preferably a number of 0.6 to 3, further preferably a number of 0.8 to 2.5, and most preferably. Is a number from 1 to 2. Z in the above formula (1) is a positive number larger than 0, and can arbitrarily take a range determined by y and the above formula (1).

Examples of the order in which the component (a), the component (b), the component (c), the component (d), and the component (e) are brought into contact include the following orders.
<1> After contacting component (d) and component (e), contact component (b), then contact component (a), and then contact component (c).
<2> After contacting component (d) and component (e), contact component (a), then contact component (b), and then contact component (c).
<3> Component (d) and component (a) are contacted, then component (b) is contacted, and then component (c) is contacted.
<4> Component (d) and component (b) are contacted, then component (a) is contacted, and then component (c) is contacted.
The contact order is preferably <1>.

  The contact treatment of component (a), component (b), component (c), component (d) and component (e) is preferably carried out in an inert gas atmosphere. The treatment temperature is usually −100 to 300 ° C., preferably −80 to 200 ° C. The treatment time is usually 1 minute to 200 hours, preferably 10 minutes to 100 hours.

  As a metal atom (M) of the metallocene complex of the said component (B), a periodic table group IV atom is preferable, and a zirconium atom and a hafnium atom are more preferable.

  As a crosslinking group of the metallocene complex of the said component (B), a methylene group, a dimethylmethylene group, and an ethylene group are preferable, More preferably, it is an ethylene group.

  As the remaining substituents that the metal atom of the metallocene complex of the component (B) has, a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 20 carbon atoms, a carbon atom number of 3 10 cycloalkyl groups, aralkyl groups having 7 to 20 carbon atoms, aryl groups having 6 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, aralkyloxy groups having 7 to 20 carbon atoms, carbon atoms 6-20 aryloxy group, silyl group optionally having 1-20 carbon atoms hydrocarbyl group as a substituent, hydrocarbyl group having 1-20 carbon atoms as a substituent The amino group which may be sufficient is mentioned. Preferably, a chlorine atom, a bromine atom, an iodine atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an aryloxy group having 6 to 10 carbon atoms, or an alkyl group having 1 to 6 carbon atoms An amino group optionally having a hydrocarbyl group as a substituent, particularly preferably a chlorine atom, a bromine atom, an iodine atom, an alkoxy group having 1 to 10 carbon atoms, or an aryl having 6 to 10 elementary atoms An amino group which may have an oxy group or a hydrocarbyl group having 1 to 6 carbon atoms as a substituent. Specifically, phenoxy group, 4-methylphenoxy group, 2,3,4-trimethylphenoxy group, 2,3,5-trimethylphenoxy group, 2,3,6-trimethylphenoxy group, 2,4,6- Examples include trimethylphenoxy group, 3,4,5-trimethylphenoxy group, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, sec-butoxy group, isobutoxy group, dimethylamino group, and diethylamino group. Particularly preferred are a phenoxy group and a dimethylamino group.

（式中、

Ｒ^１およびＲ^２は、同一または相異なり、
ハロゲン原子を置換基として有していてもよい炭素原子数１〜２０のアルキル基、
ハロゲン原子を置換基として有していてもよい炭素原子数３〜１０のシクロアルキル基、
ハロゲン原子を置換基として有していてもよい炭素原子数２〜２０のアルケニル基、
ハロゲン原子を置換基として有していてもよい炭素原子数２〜２０のアルキニル基、
ハロゲン原子を置換基として有していてもよい炭素原子数７〜２０のアラルキル基、または
ハロゲン原子を置換基として有していてもよい炭素原子数６〜２０のアリール基を表し、Ｒ^３およびＲ^４は、同一または相異なり、水素原子、
ハロゲン原子を置換基として有していてもよい炭素原子数１〜２０のアルキル基、
ハロゲン原子を置換基として有していてもよい炭素原子数３〜１０のシクロアルキル基、
ハロゲン原子を置換基として有していてもよい炭素原子数２〜２０のアルケニル基、
ハロゲン原子を置換基として有していてもよい炭素原子数２〜２０のアルキニル基、
ハロゲン原子を置換基として有していてもよい炭素原子数７〜２０のアラルキル基、または
ハロゲン原子を置換基として有していてもよい炭素原子数６〜２０のアリール基を表し、
Ｒ^５からＲ^８は、同一または相異なり、水素原子、
ハロゲン原子を置換基として有していてもよい炭素原子数１〜２０のアルキル基、
ハロゲン原子を置換基として有していてもよい炭素原子数３〜１０のシクロアルキル基、
ハロゲン原子を置換基として有していてもよい炭素原子数２〜２０のアルケニル基、
ハロゲン原子を置換基として有していてもよい炭素原子数２〜２０のアルキニル基、
ハロゲン原子を置換基として有していてもよい炭素原子数７〜２０のアラルキル基、
ハロゲン原子を置換基として有していてもよい炭素原子数６〜２０のアリール基、
ハロゲン原子を置換基として有していてもよい炭素原子数１〜２０のアルコキシ基、
ハロゲン原子を置換基として有していてもよい炭素原子数７〜２０のアラルキルオキシ基
、
ハロゲン原子を置換基として有していてもよい炭素原子数６〜２０のアリールオキシ基、炭素原子数１〜２０のハイドロカルビル基もしくはハロゲン化ハイドロカルビル基を置換基として有していてもよいシリル基、
炭素原子数１〜２０のハイドロカルビル基もしくはハロゲン化ハイドロカルビル基を置換基として有していてもよいアミノ基、または
ヘテロ環式化合物残基を表し、
Ｒ^１およびＲ^３、Ｒ^２およびＲ^４、Ｒ^５およびＲ^６、Ｒ^５およびＲ^７、Ｒ^７およびＲ^８は
、連結して環を形成してもよく、該環は置換基を有していてもよい。） As a ligand having a cyclopentadienyl skeleton of the metallocene complex of the component (B)

(Where

R ¹ and R ² are the same or different,
An alkyl group having 1 to 20 carbon atoms which may have a halogen atom as a substituent,
A cycloalkyl group having 3 to 10 carbon atoms which may have a halogen atom as a substituent,
An alkenyl group having 2 to 20 carbon atoms which may have a halogen atom as a substituent,
An alkynyl group having 2 to 20 carbon atoms which may have a halogen atom as a substituent,
An aralkyl group having 7 to 20 carbon atoms which may have a halogen atom as a substituent, or an aryl group having 6 to 20 carbon atoms which may have a halogen atom as a substituent, R ³ and R ⁴ is the same or different and is a hydrogen atom,
An alkyl group having 1 to 20 carbon atoms which may have a halogen atom as a substituent,
A cycloalkyl group having 3 to 10 carbon atoms which may have a halogen atom as a substituent,
An alkenyl group having 2 to 20 carbon atoms which may have a halogen atom as a substituent,
An alkynyl group having 2 to 20 carbon atoms which may have a halogen atom as a substituent,
An aralkyl group having 7 to 20 carbon atoms which may have a halogen atom as a substituent, or an aryl group having 6 to 20 carbon atoms which may have a halogen atom as a substituent;
R ⁵ to R ⁸ are the same or different and each represents a hydrogen atom,
An alkyl group having 1 to 20 carbon atoms which may have a halogen atom as a substituent,
A cycloalkyl group having 3 to 10 carbon atoms which may have a halogen atom as a substituent,
An alkenyl group having 2 to 20 carbon atoms which may have a halogen atom as a substituent,
An alkynyl group having 2 to 20 carbon atoms which may have a halogen atom as a substituent,
An aralkyl group having 7 to 20 carbon atoms which may have a halogen atom as a substituent,
An aryl group having 6 to 20 carbon atoms which may have a halogen atom as a substituent;
An alkoxy group having 1 to 20 carbon atoms which may have a halogen atom as a substituent;
An aralkyloxy group having 7 to 20 carbon atoms which may have a halogen atom as a substituent;
The aryloxy group having 6 to 20 carbon atoms which may have a halogen atom as a substituent, the hydrocarbyl group or halogenated hydrocarbyl group having 1 to 20 carbon atoms as a substituent Good silyl group,
An amino group optionally having a hydrocarbyl group having 1 to 20 carbon atoms or a halogenated hydrocarbyl group as a substituent, or a heterocyclic compound residue;
R ¹ and R ³ , R ² and R ⁴ , R ⁵ and R ⁶ , R ⁵ and R ⁷ , R ⁷ and R ⁸ may be linked to form a ring, and the ring has a substituent. It may be. )

Preferred examples of the metallocene complex of the component (B) include the following compounds (B-1) and (B-2). From the viewpoint of mechanical strength such as tensile impact strength, more preferably (B-1 ).

  Moreover, the compound which changed the phenoxy group of these compounds into the dimethylamino group or the diethylamino group, and the compound which changed the zirconium atom into the hafnium atom are also mentioned preferably.

  The organoaluminum compound of component (C) is preferably triisobutylaluminum, trinormal octylaluminum, triethylaluminum, or trimethylaluminum.

The amount of the metallocene complex used as the component (B) is preferably 5 × 10 ^{−6 to} 5 × 10 ⁻⁴ mol with respect to 1 g of the promoter support of the component (A). The amount of the organoaluminum compound used as the component (C) is preferably a ratio of the number of moles of aluminum atoms in the organoaluminum compound as the component (C) to the number of moles of metal atoms in the metallocene complex as the component (B) (Al / M ) And 1 to 5000.

  In the polymerization catalyst obtained by contacting the promoter support (A), the metallocene complex (B) and the organoaluminum compound (C), the promoter support (A), the metallocene complex (B), and It is good also as a polymerization catalyst which makes an electron-donating compound (D) contact an organoaluminum compound (C). Specific examples of the electron donating compound (D) include tertiary amines and secondary amines. Tertiary amines are preferable, and specific examples include triethylamine and trinormaloctylamine.

  From the viewpoint of increasing the molecular weight distribution of the obtained ethylene-α-olefin copolymer, the electron donating compound (D) is preferably used, and the amount of the electron donating compound (D) used is an organoaluminum compound. The amount is more preferably 0.1 mol% or more, still more preferably 1 mol% or more, relative to the number of moles of aluminum atoms in (C). In addition, from the viewpoint of increasing the polymerization activity, the amount used is preferably 30 mol% or less, and more preferably 20 mol% or less.

  The ethylene-α-olefin copolymer used in the present invention can be polymerized by a continuous gas phase polymerization method. The gas phase polymerization reaction apparatus used in the polymerization method 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 for supplying each component of the polymerization catalyst used in the production of the ethylene-α-olefin copolymer used in the present invention to the reaction vessel, usually, an inert gas such as nitrogen or argon, hydrogen, ethylene or the like is used. Then, a method of supplying in a state free from moisture, or a method of supplying each component in a solution or slurry after dissolving or diluting each component in a solvent is used. Each component of the catalyst may be supplied individually, or arbitrary components may be supplied in contact in advance in an arbitrary order. In the production of the ethylene-α-olefin copolymer used in the present invention, it is preferable to carry out prepolymerization and to use the prepolymerized prepolymerized catalyst component as a catalyst component or catalyst for the main polymerization.

  The polymerization temperature of the ethylene-α-olefin copolymer used in the present invention is preferably 60 to 100 ° C, more preferably 65 to 90 ° C, still more preferably 70 to 90 ° C, and particularly preferably 75 to 90 ° C. Yes, most preferably 80-90 ° C. By increasing the polymerization temperature, the molecular weight distribution can be narrowed.

  In order to adjust the melt fluidity of the ethylene-α-olefin copolymer used in the present invention, hydrogen may be added to the polymerization reactor as a molecular weight regulator.

  Multi-stage polymerization may be performed for the purpose of widening the molecular weight distribution of the ethylene-α-olefin copolymer used in the present invention.

  In the present invention, the above-mentioned ethylene-α-olefin copolymer can be molded together with an additive and a polyolefin different from the ethylene-α-olefin copolymer as necessary to obtain a steel material coating. Examples of the additive include antioxidants, weathering agents, lubricants, antiblocking agents, antistatic agents, antifogging agents, dripping agents, pigments, fillers, and mold release agents. Examples of the polyolefin different from the ethylene-α-olefin copolymer include, for example, high density polyethylene, low density polyethylene, very low density polyethylene, ultra low density polyethylene, and ethylene having a flow activation energy of less than 40 kJ / mol. α-olefin copolymer, polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid copolymer, ethylene-methacrylic acid ester copolymer And polyolefin rubber.

  Additives such as antioxidants, antiblocking agents, lubricants, antistatic agents, processability improvers, pigments, and other resins added as necessary are the ethylene-α-olefin copolymer used in the present invention. The polymer or its composition may be melt-kneaded in advance, or the ethylene-α-olefin copolymer or its composition may be dry blended and used for molding, or one or more master batches May be prepared and dry blended into an ethylene-α-olefin copolymer or a composition thereof for use in molding.

  The ethylene-α-olefin copolymer of the present invention or a composition thereof is used for coating steel materials. In the present invention, the steel material means iron products such as iron pipes and iron plates; stainless steel products such as stainless steel tubes and stainless steel plates; non-ferrous metals such as copper tubes, copper plates, aluminum tubes, aluminum plates, zinc tubes, zinc plates, lead tubes, lead plates Includes products.

  As a method of coating a steel material with the ethylene-α-olefin copolymer of the present invention or a resin composition containing the copolymer and an additive or a polyolefin different from the ethylene-α-olefin copolymer, a known method is used. Preferably, a resin containing the ethylene-α-olefin copolymer of the present invention is melt-extruded from a die such as a T die, a crosshead die, or a circular die to the surface of a steel material and coated. is there. The steel material obtained by such a method is coated with an ethylene-α-olefin copolymer or a resin composition containing a polyolefin different from the copolymer and an additive or the ethylene-α-olefin copolymer. The coating part which consists of an ethylene-alpha-olefin copolymer of this invention has the small dispersion | variation in low temperature impact strength, and is excellent in heat resistance.

Hereinafter, the present invention will be described with reference to examples and comparative examples.
The physical properties in Examples and Comparative Examples were measured according to the following methods.

(1) Density (d, unit: kg / m ³ )
It measured according to the method prescribed | regulated to A method among JISK7112-1980. The sample was annealed according to JIS K6760-1995.

(2) Melt flow rate (MFR, unit: g / 10 minutes)
In the method defined in JIS K7210-1995, measurement was performed by the A method under the conditions of a load of 21.18 N and a temperature of 190 ° C.

(3) Melt flow rate ratio (MFRR)
In the method specified in JIS K7210-1995, the test load is 211.82N, the melt flow rate (H-MFR) measured at a measurement temperature of 190 ° C., and the method specified in JIS K7210-1995 is the load 21 The melt flow rate (MFR) measured under the conditions of .18 N and a temperature of 190 ° C. was measured and obtained as a value obtained by dividing H-MFR by MFR.

(4) Molecular weight distribution (Mw / Mn, Mz / Mw)
Using gel permeation chromatograph (GPC) method, measure z-average molecular weight (Mz), weight-average molecular weight (Mw) and number-average molecular weight (Mn) under the following conditions (1) to (8) Mw / Mn and Mz / Mw were obtained. The baseline on the chromatogram is a stable horizontal region with a sufficiently long retention time than the appearance of the sample elution peak and a stable horizontal region with a sufficiently long retention time than the solvent elution peak was observed. A straight line formed by connecting the points.
(1) Equipment: Waters 150C manufactured by Waters
(2) Separation column: TOSOH TSKgelGMH6-HT
(3) Measurement temperature: 140 ° C
(4) Carrier: Orthodichlorobenzene
(5) Flow rate: 1.0 mL / min
(6) Injection volume: 500 μL
(7) Detector: Differential refraction
(8) Molecular weight reference material: Standard polystyrene

(5) Long chain branching amount (LCB amount; N _LCB ), short chain branching amount (SCB; N _SCB ), (unit: piece / 1000 C)
The number of long-chain branches or short-chain branches per 1000 carbon atoms is determined by the carbon nuclear magnetic resonance ( ¹³ C-NMR) method and the carbon nuclear magnetic resonance ( ¹³ C-NMR) of the polymer according to the following measurement conditions. The spectrum was measured, and the number of long chain branches or short chain branches per 1000 carbon atoms in the polymer was determined by the following calculation method.

(Measurement condition)
Apparatus: AVANCE600 manufactured by Bruker
Measurement probe: 10 mm cryoprobe Measurement solvent: 1,2-dichlorobenzene / 1,2-dichlorobenzene-d4
= 75/25 (volume ratio) mixed solution measurement temperature: 130 ° C.
Measurement method: proton decoupling method Pulse width: 45 degrees Pulse repetition time: 4 seconds Measurement standard: Tetramethylsilane window function: Exponential or Gaussian integration number: 2500

Calculation method of long chain branching amount (LCB amount) In NMR spectrum in which window function is processed with Gaussian, carbon atom number is 7 or more when sum of peak areas of all peaks having peak top at 5 to 50 ppm is 1000 The peak area of the peak derived from the methine carbon to which the branches were bonded was determined as the amount of long-chain branching (number of branches having 7 or more carbon atoms). Under these measurement conditions, the peak area of a peak having a peak top in the vicinity of 38.22 to 38.27 ppm was determined as the amount of long chain branching (number of branches having 7 or more carbon atoms). The peak area of the peak was defined as the area of the signal in the range from the chemical shift of the valley with the adjacent peak on the high magnetic field side to the chemical shift of the valley with the adjacent peak on the low magnetic field side. In this measurement condition, in the measurement of the ethylene-1-octene copolymer, the peak top position of the peak derived from the methine carbon to which the hexyl branch was bonded was 38.21 ppm.

Calculation method of short chain branching amount (SCB amount) When the comonomer is hexene, a branch having 4 carbon atoms is bound when the sum of the peak areas of all peaks having a peak top at 5 to 50 ppm is 1000 in the NMR spectrum obtained by treating the window function with an exponential. The peak area derived from the methine carbon was calculated as the amount of short chain branching. In this measurement condition, it calculated | required from the total value of the area of a peak of 38.0-38.21 ppm and the area of a peak of 35.85-36.00 ppm.
2. When the comonomer is hexene and butene, in the NMR spectrum in which the window function is processed with the exponential, the branching with 2 carbon atoms when the sum of the peak areas of all peaks having a peak top at 5 to 50 ppm is 1000 The peak area derived from the methine carbon bonded to the methine carbon and the peak area derived from the methine carbon bonded to the branch having 4 carbon atoms were calculated as the amount of short chain branching. In this measurement condition, it calculated | required from the total value of the area of 39.60-39.85 ppm, the area of the peak of 38.00-38.21 ppm, and the area of the peak of 35.85-36.00 ppm.

(6) g *
G * was determined by the formula (I).
[Η] represents the relative viscosity (ηrel) of the ethylene-α-olefin copolymer in 100 ml of tetralin containing 0.5% by weight of butylhydroxytoluene (BHT) as a thermal degradation inhibitor, and ethylene-α-olefin. A sample solution was prepared by dissolving 100 mg of the copolymer at 135 ° C., and using a Ubbelohde viscometer, the sample solution and a blank solution composed of tetralin containing only 0.5% by weight of BHT as a thermal degradation inhibitor Calculated from the fall time and determined by the formula (II), [η] _GPC is determined by the formula (I-II) from the measurement of the molecular weight distribution of the ethylene-α-olefin copolymer of (4), g _SCB * was calculated | required by Formula (I-III) from the measurement of the amount of short chain branches of the ethylene-alpha-olefin copolymer of (5).

(7) Differential scanning calorimetry The ethylene-α-olefin copolymer was pressed for 5 minutes at a pressure of 10 MPa with a hot press at 150 ° C. and then cooled for 5 minutes with a cooling press at 30 ° C. to obtain a thickness of about The sheet was molded into a 100 μm sheet, and a sample of about 10 mg was cut out from the sheet and sealed in an aluminum pan. Next, the aluminum pan in which the sample was sealed was held at a differential scanning calorimeter (differential scanning calorimeter DSC-7 manufactured by Perkin Elmer Co., Ltd.) (1) at 150 ° C. for 5 minutes, and (2) 5 ° C. (3) Hold at 20 ° C. for 2 minutes, (4) Increase the temperature from 20 ° C. to 150 ° C. at 5 ° C./minute, and calculate the melting curve in (4) It was measured. From the obtained melting curve, the number of melting peaks existing in the range from 25 ° C. to 150 ° C. and the temperature showing the maximum melting peak with the highest peak height were determined. In addition, when there were a plurality of melting peaks, a temperature showing a melting peak different from the maximum melting peak was also obtained.

(8) Melting component ratio at 110 ° C. or higher (HH110, unit:%)
From the melting curve obtained by differential scanning calorimetry of the ethylene-α-olefin copolymer of (7) above, the melting curve at 110 ° C. or higher and the baseline within the peak area in the range from 25 ° C. to 150 ° C. The ratio of the enclosed area was calculated and set to HH 110%. It shows that heat resistance is so high that this value is large.
(9) Flexural modulus (unit: MPa)
The flexural modulus was measured at 23 ° C. using a 75 mm × 25 mm × 1 mm thick sample piece according to ASTM D747. The sample piece was molded by hot pressing at 150 ° C., stored in a temperature-controlled room at 23 ° C. and 50% humidity for 24 hours or more, and then used for measurement. It shows that rigidity is so high that this value is high.

(10) Flow activation energy (Ea, unit: kJ / mol)
Using a viscoelasticity measuring device (Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics), a melt complex viscosity-angular frequency curve at 130 ° C., 150 ° C., 170 ° C. and 190 ° C. was measured under the following measurement conditions. From the obtained melt complex viscosity-angular frequency curve, calculation software Rhios V. Using 4.4.4, a master curve of the melt complex viscosity-angular frequency curve at 190 ° C. was created, and the activation energy (Ea) of the flow was determined.
<Measurement conditions>
Geometry: Parallel plate Plate diameter: 25mm
Plate spacing: 1.5-2mm
Strain: 5%
Angular frequency: 0.1 to 100 rad / sec Measurement atmosphere: Nitrogen

(11) Melt complex viscosity (η *, unit: Pa · sec)
In the measurement of the activation energy of flow in (10), the melt complex viscosity measured at a temperature of 190 ° C. and an angular frequency of 100 rad / sec was obtained. The lower the melt complex viscosity, the smaller the extrusion load during extrusion molding, and the better the extrusion moldability.

(12) Characteristic relaxation time (τ ₀ , unit: s ⁻¹ )
Τ ₀ was obtained by approximating the master curve of the melt complex viscosity-angular frequency curve at 190 ° C. obtained in the measurement of the flow activation energy of (10) by the following formula (5).
η = η ₀ / [1+ (τ ₀ × ω) ⁿ ] (5)
η: melt complex viscosity (unit: Pa · sec)
ω: angular frequency (unit: rad / sec)
τ ₀ : Characteristic relaxation time (unit: s ⁻¹ )
η ₀ : Constant determined for each ethylene-α-olefin copolymer (unit: Pa · second)
n: Constant determined for each ethylene-α-olefin copolymer

(13) Melt tension (MT, unit: cN)
Using a melt tension tester manufactured by Toyo Seiki Seisakusho, an ethylene-α-olefin copolymer was melt-extruded from an orifice having a diameter of 2.095 mm and a length of 8 mm at a temperature of 190 ° C. and an extrusion speed of 0.32 g / min. The melted ethylene-α-olefin copolymer was drawn into a filament by a take-up roll at a take-up rate of 6.3 (m / min) / min, and the tension during take-up was measured. The maximum tension from the start of take-up until the filamentous ethylene-α-olefin copolymer was cut was defined as the melt tension.
The higher this value, the more stable the resin melt shape at the time of coating the steel material, and the easier it is to obtain a steel material having a resin coating portion with a uniform thickness.

(14) Maximum take-up speed (MTV, unit: m / min)
In the measurement of the melt tension of (13), the take-up speed when the filamentous ethylene-α-olefin copolymer was cut was defined as the maximum take-up speed. The higher this value, the better the take-up property at the time of extrusion molding.

(15) Impact strength (unit: kJ / m ² )
The measurement of impact strength was performed at 23 ° C. in an S-type dumbbell shape according to ASTM D1822-61T. The sample piece was molded by hot pressing at 150 ° C., stored in a temperature-controlled room at 23 ° C. and 50% humidity for 24 hours or more, and then used for measurement. The larger this value, the better the impact resistance.

(16) Low temperature impact strength (unit: kJ / m ² )
The low temperature impact strength was measured under the condition of −40 ° C. using a type 1 test piece shape in accordance with JIS K7160 except that the notch shape of the test piece was changed to a tip radius of 0.25 ± 0.05 mm. The sample piece was molded by hot pressing at 150 ° C., stored in a temperature-controlled room at 23 ° C. and 50% humidity for 24 hours or more, and then used for measurement. The larger this value, the better the impact resistance at low temperatures.

(17) Low temperature impact strength stability (coefficient of variation, unit:%)
The evaluation of stability at low temperature impact strength is obtained by dividing the standard deviation of 8 measured values excluding the maximum and minimum values from the 10 measurement results obtained for each sample during the above-mentioned low temperature impact strength measurement by the average of the measured values. The coefficient of variation derived from this was used. The smaller the number, the smaller the difference in strength between the test specimens, and the less the low-temperature impact strength variation can be provided.
Coefficient of variation (CV%) = standard deviation (σ) / average value (X)

(18) Cold xylene soluble part (unit: wt%)
In a 200 mL flat bottom flask equipped with a reflux condenser, about 0.5 g of an ethylene-α-olefin copolymer sample and 100 mL of xylene were charged and refluxed for 30 minutes. After refluxing, the flat bottom flask was allowed to stand in an atmosphere of about 25 ° C. for 20 minutes, and then left in a water bath adjusted to 25 ° C. for 1 hour. After standing, the solution in the flat bottom flask was filtered with a filter paper (for No. 50 chromatography). The obtained filtrate was subjected to liquid chromatographic analysis under the following conditions (1) to (7), the amount of the copolymer dissolved in the solution was calculated, and the cold xylene-dissolved component ratio was determined from the sample weight.
(1) Apparatus: Degasser DG-2080-53 manufactured by JASCO Corporation
(2) Column: SHODEX GPC KF-801
(3) Column oven: CO-2065Plus manufactured by JASCO Corporation, setting 30 ° C
(4) Eluent: Tetrahydrofuran (for liquid chromatograph)
(5) Flow rate: 1.0 mL / min
(6) Injection volume: 110 μL
(7) Detector: differential refractometer The smaller this value, the better the solvent resistance.

(19) Amount of oligomer (ΣCn; n = 12-18, unit: ppm)
The ethylene-α-olefin copolymer is pressed for 5 minutes at a pressure of 10 MPa with a hot press at 150 ° C. and then cooled for 5 minutes with a cooling press at 30 ° C. to form a sheet having a thickness of about 100 μm to 200 μm. did. About 1 g of a sample was cut out from the sheet, and the oligomer component was extracted by ultrasonic extraction using 10 ml of THF solvent. The oligomer component was quantified by the GC method. The measuring apparatus and each measurement condition are as follows.
<Measurement conditions>
GC measuring device: GC-2010 manufactured by SHIMADZU
Column: DB-1 manufactured by J & W
(Film thickness 0.15 μm, length 15 m, inner diameter 0.53 mm) Connection detector (FID) temperature: 310 ° C.
Measurement column temperature: held at 100 ° C. for 1 minute, then heated up to 310 ° C. at 10 ° C./minute, the total of detection peak areas of hydrocarbons having 12 to 18 carbon atoms in the gas chromatogram chart is the carbon atom This was converted to the hydrocarbon concentration (ppm) of Equation 18.
The smaller the numerical value, the more the smoke generated during the process of coating the resin on the steel material can be suppressed, and the lowering of the adhesion between the resin part and the coated steel material due to the contamination of the coated steel material can be suppressed.

(20) Smoke (unit: Count / min)
Covers the die outlet of a T-die sheet molding machine (Union Plastics, USV30 non-vent type extruder, T-die width 250 mm, die lip opening 1 mm) with a digital dust meter (Shibata) Science Co., Ltd., LD-5D, light scattering type) was connected. The number of fuming particles generated from the resin extruded from the T-die sheet molding machine was measured for 1 minute under the conditions of a die temperature of 260 ° C., a cylinder temperature of 260 ° C., and a screw rotation speed of 100 rpm.
The obtained numerical value (unit: Count / min) was used as the evaluation value of smoke generation. The smaller this value is, the less smoke is generated during extrusion molding.

Example 1
(1) Preparation of solid component (a-1) Silica heated by a reactor equipped with a nitrogen-replaced stirrer at 300 ° C. under a nitrogen stream (Sypolol 948 manufactured by Devison; 50% volume average particle diameter = 55 μm; (Pore volume = 1.67 ml / g; specific surface area = 325 m ² / g) 2.8 kg and 24 kg of toluene were added and stirred. Thereafter, after cooling to 5 ° C., a mixed solution of 0.9 kg of 1,1,1,3,3,3-hexamethyldisilazane and 1.4 kg of toluene was maintained for 30 minutes while maintaining the reactor temperature at 5 ° C. It was dripped at. After completion of dropping, the mixture was stirred at 5 ° C. for 1 hour, then heated to 95 ° C., stirred at 95 ° C. for 3 hours, and filtered. The obtained solid product was washed 6 times with 20.8 kg of toluene. Thereafter, 7.1 kg of toluene was added to form a slurry, which was allowed to stand overnight.

To the slurry obtained above, 1.73 kg of diethylzinc in hexane (diethylzinc concentration: 50% by weight) and 1.02 kg of hexane were added and stirred. Then, after cooling to 5 ° C., a mixed solution of 0.78 kg of 3,4,5-trifluorophenol and 1.44 kg of toluene was added dropwise over 60 minutes while maintaining the temperature of the reactor at 5 ° C. After completion of dropping, the mixture was stirred at 5 ° C. for 1 hour, then heated to 40 ° C. and stirred at 40 ° C. for 1 hour. Then, it cooled to 22 degreeC and 0.11 kg of water was dripped in 1.5 hours, keeping the temperature of a reactor at 22 degreeC. After completion of dropping, the mixture was stirred at 22 ° C. for 1.5 hours, then heated to 40 ° C., stirred at 40 ° C. for 2 hours, further heated to 80 ° C., and stirred at 80 ° C. for 2 hours. After stirring, at room temperature, the supernatant was withdrawn to a residual amount of 16 L, charged with 11.6 kg of toluene, then heated to 95 ° C. and stirred for 4 hours. After stirring, the supernatant liquid was extracted at room temperature to obtain a solid product. The obtained solid product was washed 4 times with 20.8 kg of toluene and 3 times with 24 liters of hexane. Thereafter, the solid component was obtained by drying (hereinafter referred to as promoter support (a-1)).

(2) Preparation of pre-polymerization catalyst component (b-1) After 80 liters of butane was charged into an autoclave with a stirrer having an internal volume of 210 liters that had been previously purged with nitrogen, racemic ethylene (indenyl) (5, 6, 7, 8-tetrahydro-5,5,8,8-tetramethylbenz [f] indenyl) zirconium diphenoxide (101 mmol) was added, and the autoclave was heated to 50 ° C. and stirred for 2 hours. Next, after the temperature of the autoclave is lowered to 30 ° C. and the system is stabilized, 0.03 MPa of ethylene is charged at the gas phase pressure in the autoclave, and 0.7 kg of the promoter support (a-1) is added. Polymerization was started by adding 158 mmol of triisobutylaluminum. After 30 minutes while continuously supplying ethylene at 0.7 kg / Hr, the temperature was raised to 50 ° C., and ethylene and hydrogen were respectively 3.5 kg / Hr and 5.5 liters (room temperature and normal pressure volume) / Hr. A total of 4 hours of prepolymerization was carried out by continuous feeding. After completion of the polymerization, ethylene, butane, hydrogen gas, etc. are purged and the remaining solid is vacuum-dried at room temperature, and a prepolymerized catalyst component (23 g of polyethylene preliminarily polymerized per 1 g of the cocatalyst carrier (a-1) ( b-1) was obtained.

(3) Production of ethylene-1-hexene copolymer (PE-1) Using the prepolymerized catalyst component (b-1) obtained above, ethylene and 1-hexene were co-polymerized in a continuous fluidized bed gas phase polymerization apparatus. Polymerization was performed to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 87 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 0.71%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.31%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Moreover, the said prepolymerization catalyst component (b-1), triisobutylaluminum, and triethylamine (3% of molar ratio with respect to triisobutylaluminum) were supplied continuously, and the total powder weight of 80 kg of the fluidized bed was maintained constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel), feed rate 50 kg / hr, screw rotation speed 450 rpm, gate opening 50%, suction pressure 0.1 MPa, resin temperature 200-230 ° C. The ethylene-1-hexene copolymer was obtained by granulation under the conditions of The results of physical property evaluation of the obtained copolymer are shown in Table 1. Moreover, the melting curve of the obtained copolymer was shown in FIG.

Example 2

(1) Production of ethylene-1-hexene copolymer (PE-2) Example 1 Using the prepolymerized catalyst component (b-1) obtained above, ethylene and 1- Hexene copolymerization was carried out to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 87 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 0.52%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.30%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Moreover, the said prepolymerization catalyst component (b-1), triisobutylaluminum, and triethylamine (3% of molar ratio with respect to triisobutylaluminum) were supplied continuously, and the total powder weight of 80 kg of the fluidized bed was maintained constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-hexene copolymer (PE-2) was obtained. The results of physical property evaluation of the obtained copolymer are shown in Table 1.

Example 3
(1) Production of ethylene-1-hexene copolymer (PE-3) Using a prepolymerization catalyst component (b-1) obtained by the same method as in Example 1, ethylene and Copolymerization of 1-hexene was carried out to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 87 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 0.98%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.39%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Moreover, the said prepolymerization catalyst component (b-1), triisobutylaluminum, and triethylamine (molar ratio 30% with respect to triisobutylaluminum) were supplied continuously, and the total powder weight of 80 kg of a fluid bed was maintained constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-hexene copolymer (PE-3) was obtained. The results of physical property evaluation of the obtained copolymer are shown in Table 1.

Example 4
(1) Production of ethylene-1-hexene copolymer (PE-4) Using a prepolymerization catalyst component (b-1) obtained by the same method as in Example 1, ethylene and Copolymerization of 1-hexene was carried out to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 87 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 1.11%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.45%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Moreover, the said prepolymerization catalyst component (b-1), triisobutylaluminum, and triethylamine (molar ratio 30% with respect to triisobutylaluminum) were supplied continuously, and the total powder weight of 80 kg of a fluid bed was maintained constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-hexene copolymer (PE-4) was obtained. The results of physical property evaluation of the obtained copolymer are shown in Table 1.

Example 5
(1) Production of ethylene-1-hexene copolymer (PE-5) Using a prepolymerized catalyst component (b-1) obtained by the same method as in Example 1, ethylene and Copolymerization of 1-hexene was carried out to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 80 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 1.04%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.26%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Moreover, the said prepolymerization catalyst component (b-1), triisobutylaluminum, and triethylamine (molar ratio 30% with respect to triisobutylaluminum) were supplied continuously, and the total powder weight of 80 kg of a fluid bed was maintained constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-hexene copolymer (PE-5) was obtained. The results of physical property evaluation of the obtained copolymer are shown in Table 1.

Example 6
(1) Production of ethylene-1-hexene copolymer (PE-6) Using a prepolymerized catalyst component (b-1) obtained by the same method as in Example 1, ethylene and Copolymerization of 1-hexene was carried out to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 87 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 0.98%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.34%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Moreover, the said prepolymerization catalyst component (b-1), triisobutylaluminum, and triethylamine (3% of molar ratio with respect to triisobutylaluminum) were supplied continuously, and the total powder weight of 80 kg of the fluidized bed was maintained constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-hexene copolymer (PE-6) was obtained. The results of physical property evaluation of the obtained copolymer are shown in Table 1.

Comparative Example 1
(1) Preparation of prepolymerization catalyst component (b-2) 80 liters of butane was introduced into an autoclave with a stirrer having an internal volume of 210 liters that had been previously purged with nitrogen, and then 101 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide. The autoclave was heated to 50 ° C. and stirred for 2 hours. Next, after the temperature of the autoclave was lowered to 30 ° C. and the system was stabilized, ethylene was charged in an amount of 0.03 MPa at the gas phase pressure in the autoclave, and 0.7 kg of the promoter support (a-1) obtained in Example 1 was added. The polymerization was started by charging 158 mmol of triisobutylaluminum. After 30 minutes while continuously supplying ethylene at 0.7 kg / hour, the temperature was raised to 50 ° C., and ethylene and hydrogen were supplied at 3.5 kg / hour and 5.5 liters (room temperature and normal pressure volume) / hour, respectively. A total of 4 hours of prepolymerization was carried out by continuous feeding. After completion of the polymerization, the remaining solids purged with ethylene, butane, hydrogen gas and the like are vacuum-dried at room temperature, and a prepolymerized catalyst component (20 g of polyethylene preliminarily polymerized per 1 g of the promoter support (a-1) ( b-2) was obtained.

(2) Production of ethylene-1-butene 1-hexene copolymer (PE-7) Using the prepolymerized catalyst component (b-2) obtained by the same method as Comparative Example 1, a continuous fluidized bed gas phase polymerization apparatus Then, ethylene and 1-hexene were copolymerized to obtain a polymer powder. As polymerization conditions, the polymerization temperature is 87 ° C., the polymerization pressure is 2 MPa, the hydrogen molar ratio to ethylene is 1.10%, the 1-hexene molar ratio to the total of ethylene, 1-hexene and 1-butene is 0.90%, The 1-butene molar ratio relative to the total of ethylene, 1-hexene and 1-butene was 1.75%. During the polymerization, ethylene, 1-hexene, 1-butene and hydrogen were continuously supplied in order to keep the gas composition constant. Further, the prepolymerization catalyst component (b-9), triisobutylaluminum, and triethylamine (a molar ratio of 3% with respect to triisobutylaluminum) were continuously supplied, and the total powder weight of 80 kg in the fluidized bed was kept constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-butene-1-hexene copolymer (PE-7) was obtained. The ethylene 1-butene-1-hexene copolymer (PE-7) has a 1-butene-derived short-chain branching amount of 6.3 / 1000 C per 1000 carbon atoms, and a 1-hexene-derived short-chain branching. The amount was 10.7 / 1000 C per 1000 carbon atoms. The results of other physical property evaluations of the obtained copolymer are shown in Table 2.

Comparative Example 2
(1) Production of ethylene-butene 1-hexene copolymer (PE-8) Using a prepolymerized catalyst component (b-2) obtained by the same method as Comparative Example 1, using a continuous fluidized bed gas phase polymerization apparatus Copolymerization of ethylene and 1-hexene was carried out to obtain a polymer powder. As polymerization conditions, the polymerization temperature is 85 ° C., the polymerization pressure is 2 MPa, the hydrogen molar ratio to ethylene is 1.65%, the 1-hexene molar ratio to the total of ethylene, 1-hexene and 1-butene is 0.90%, The 1-butene molar ratio relative to the total of ethylene, 1-hexene and 1-butene was 2.70%. During the polymerization, ethylene, 1-hexene, 1-butene and hydrogen were continuously supplied in order to keep the gas composition constant. Moreover, the said prepolymerization catalyst component (b-2), triisobutylaluminum, and triethylamine (3% of molar ratio with respect to triisobutylaluminum) were supplied continuously, and the total powder weight of 80 kg of the fluidized bed was maintained constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-butene-1-hexene copolymer (PE-8) was obtained. The amount of short chain branches derived from 1-butene of the ethylene 1-butene-1-hexene copolymer (PE-8) is 9.3 / 1000 C per 1000 carbon atoms, and 1-hexene-derived short chain branches. The amount was 11.5 / 1000 C per 1000 carbon atoms. The results of other physical property evaluations of the obtained copolymer are shown in Table 2.

Comparative Example 3
(1) Production of ethylene-1-hexene copolymer (PE-9) Using the prepolymerized catalyst component (b-2) obtained above, ethylene and 1-hexene were co-polymerized in a continuous fluidized bed gas phase polymerization apparatus. Polymerization was performed to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 87 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 1.53%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.36%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. Moreover, the said prepolymerization catalyst component (b-2), triisobutylaluminum, and triethylamine (3% of molar ratio with respect to triisobutylaluminum) were supplied continuously, and the total powder weight of 80 kg of the fluidized bed was maintained constant. The average polymerization time was 4 hours. The obtained polymer powder was fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hour, a screw speed of 450 rpm, a gate opening of 50%, a suction pressure of 0.1 MPa, and a resin temperature of 200 to 230 ° C. By granulating under the conditions, an ethylene-1-hexene copolymer (PE-9) was obtained. Table 2 shows the results of physical properties evaluation of the obtained copolymer. Moreover, the melting curve of the obtained copolymer was shown in FIG.

Comparative Example 4
(1) Production of ethylene-1-hexene copolymer (PE-10) The inside of an autoclave with a stirrer with an internal volume of 3 liters, which was dried under reduced pressure and replaced with argon, was evacuated, and the partial pressure of hydrogen became 0.002 MPa. In addition, 100 ml of 1-hexene and 650 g of butane as a polymerization solvent were charged, and the temperature was raised to 70 ° C. Thereafter, ethylene was added so that the partial pressure became 1.6 MPa, and the inside of the system was stabilized. As a result of gas chromatography analysis, the gas composition in the system was hydrogen = 0.09 mol%. To this, 0.9 ml of a hexane solution of triisobutylaluminum adjusted to a concentration of 1 mol / l as an organoaluminum compound was added. Next, 1 ml of a toluene solution of dimethylsilylene bis (3-phenylcyclopentadienyl) zirconium dichloride (racemic / meso ratio = 49.2 / 50.8) adjusted to a concentration of 1 μmol / ml was added. 8.3 mg of co-catalyst support (a-1) obtained by the same method was added. During the polymerization, polymerization was performed at 70 ° C. for 60 minutes while continuously supplying an ethylene / hydrogen mixed gas (hydrogen = 0.07 mol%). Thereafter, butane, ethylene, and hydrogen were purged to obtain 65 g of an ethylene-1-hexene copolymer (PE-10). The physical properties of the obtained copolymer are shown in Table 2.

About the ethylene-alpha-olefin copolymer of Examples 1-6 and Comparative Examples 1-3, the value of long-chain branching amount _NLCB (pieces / 1000C) was plotted with respect to the value of MFR (g / 10min). The figure is shown in FIG. ◆ is an example, and □ is a comparative example.

  The figure which showed the melting curve obtained by the differential scanning calorimetry of the ethylene-alpha-olefin copolymer of Example 1 and Comparative Example 3 is shown in FIG.

The figure which plotted the value of characteristic relaxation time (tau) ₀ (s ^<-1 >) with respect to the value of MFR (g / 10min) about the ethylene-alpha-olefin copolymer of Examples 1-6 and Comparative Examples 1-3. Is shown in FIG. ◆ is an example, and □ is a comparative example.

For the ethylene-α-olefin copolymers of Examples 1-6 and Comparative Examples 1-3, the value of oligomer amount ΣCn; n = 12-18 (ppm) is plotted against the value of MFR (g / 10 min). The resulting diagram is shown in FIG. ◆ is an example, and □ is a comparative example. Comparison was made between ethylene-α-olefin copolymers having the same MFR. The ethylene-α-olefin copolymers of Examples 1 to 4 that satisfy all the requirements of Claim 1 of the present application are compared with the ethylene-α-olefin copolymers of Comparative Examples 1 to 3 having the same MFR, The amount of oligomer is small and the smoke generated during melt molding is small.

FIG. 5 is a diagram in which the values of HH110 (%) are plotted against the values of flexural modulus (MPa) for the ethylene-α-olefin copolymers of Examples 1 to 6 and Comparative Examples 1 to 3. ◆ is an example, and □ is a comparative example. The ethylene-α-olefin copolymers of Examples 1, 2, and 6 that satisfy all the requirements of claim 1 of the present application are compared with the ethylene-α-olefin copolymer of Comparative Example 2 having the same degree of rigidity. The value of HH110 is large and the heat resistance is excellent. The ethylene-α-olefin copolymers of Examples 3, 4, and 5 that satisfy all the requirements of claim 1 of the present application are compared with the ethylene-α-olefin copolymers of Comparative Examples 1 and 3 having comparable rigidity. Thus, the value of HH110 is large and the heat resistance is excellent.

Claims (3)

It has a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, has a density of 860 to 930 kg / m ³ , and a melt flow rate (MFR) of 0.01. 10 g / 10 min, the molecular weight distribution (Mw / Mn), which is the ratio of the weight average molecular weight to the number average molecular weight, is 4.5 to 10, and the flow activation energy (Ea) is 40 to 100 kJ / mol. Ethylene having a long chain branching amount measured by NMR of 0.29 to 0.50 per 1000 carbon atoms and g * defined by the following formula (I) of 0.76 to 0.88 A resin for coating a steel material comprising an α-olefin copolymer.
g * = [η] / ([η] _GPC × g _SCB *) (I)
[Wherein [η] represents the intrinsic viscosity (unit: dl / g) of the ethylene-α-olefin copolymer, and is a value defined by the following formula (I-I). [Η] _GPC is a value defined by the following formula (I-II). g _SCB * is a value defined by the following formula (I-III).
[Η] = 23.3 × log (ηrel) (II)
(In the formula, ηrel represents the relative viscosity of the ethylene-α-olefin copolymer.)
[Η] _GPC = 0.00046 × Mv ^0.725 (I-II)
(In the formula, Mv represents the viscosity average molecular weight of the ethylene-α-olefin copolymer.)
g _SCB * = (1-A) ^1.725 (I-III)
(In the formula, A is a value defined by the following formula (IV).)
A = ((12 * n + 2n + 1) * y) / ((1000-2y-2) * 14 + (y + 2) * 15 + y * 13) (IV)
(In the formula, n represents the number of short-chain branched carbon atoms derived from the monomer unit based on the α-olefin of the ethylene-α-olefin copolymer, and y is a short number per 1000 carbon atoms. Represents the amount of chain branching.)] The ethylene-α-olefin copolymer is
In the melting curve obtained from differential scanning calorimetry, a plurality of melting peaks are shown in the range from 25 ° C. to 150 ° C.,
A melting peak different from the maximum melting peak at a temperature higher than the maximum melting peak having the highest melting peak height;
The resin for coating a steel material according to claim 1, wherein the characteristic relaxation time (τ) satisfies the formula (a-1).
τ <3.8 × MFR ^−0.62 (a-1) A steel material coated with the steel material coating resin according to claim 1.

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