JP2024094243A - Ethylene-α-olefin copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ethylene-α-olefin copolymer having relatively excellent acceptability of a filler contained as a flame retardant while maintaining adequate extrusion processability.

SOLUTION: There is provided an ethylene-α-olefin copolymer which satisfies all of the following requirements (i) to (iv). (i) the Vicat softening point is 85.0°C or less. (ii) When the melt torque at 160°C is defined as X [N m] and the melt flow rate is defined as Y [g/10 min], a value of X+6.5×Ln (Y) is 23.0 or less. (iii) The ratio of the sum of the peak heights of a medium molecular weight distribution component (B component) and a high molecular weight component (C component) to the peak height of a low molecular weight component (A component) when the differential molecular weight distribution curve is divided into three normal distribution curves is 10.00 or more. (iv) The melt flow rate is 0.10 g/10 min or more and 10.00 g/10 min or less.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an ethylene-α-olefin copolymer.

Traditionally, ethylene-α-olefin copolymers have been used in food packaging, pharmaceutical packaging, electronic component packaging, surface protection materials, and insulators and sheaths for electric wires and cables.

For example, Patent Document 1 describes an ethylene-based resin composition that contains an ethylene-α-olefin copolymer whose flow activation energy, melt flow rate, and molecular weight distribution are each within a specific range, and a flame retardant, and that can be used for sheaths to obtain extrusion molded articles with excellent appearance and mechanical strength.

Patent Document 2 describes an ethylene-α-olefin copolymer that has a melt flow rate, density, flow activation energy, molecular weight distribution, and hexane extractable amount each falling within a specific range, can be used as a food packaging material, and has excellent moldability and low smoke generation during melt processing.

JP 2007-023229 A JP 2008-106264 A

However, when the above-mentioned ethylene-α-olefin copolymer is used for electric wire coating materials, etc., it is required that the ethylene-α-olefin copolymer maintains suitable extrusion processability while increasing the acceptability of the filler contained as a flame retardant, i.e., that it contains a larger amount of filler.

The present invention was made in consideration of these circumstances, and aims to provide an ethylene-α-olefin copolymer that has relatively good acceptance of a filler contained as a flame retardant while maintaining appropriate extrusion processability.

The ethylene-α-olefin copolymer according to the present invention satisfies all of the following requirements (i) to (iv).
(i) Vicat softening point is 85.0°C or less.
(ii) When the melt torque at 160°C is X [N m] and the melt flow rate is Y [g/10 min], the value of X + 6.5 × Ln(Y) is 23.0 or less.
(iii) When the differential molecular weight distribution curve is divided into three normal distribution curves, the ratio of the sum of the peak heights of the medium molecular weight distribution component (component B) and the high molecular weight component (component C) to the peak height of the low molecular weight component (component A) is 10.00 or more.
(iv) A melt flow rate of 0.10 g/10 min or more and 10.00 g/10 min or less.

The method for producing an ethylene-α-olefin copolymer according to the present invention is a method for producing an ethylene-α-olefin copolymer having a density of 911 kg/ ^m3 or less by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of an olefin polymerization catalyst,
The polymerization conditions are adjusted so that A defined by the following formula (1) is 67.0 or more and 100.0 or less.

The present invention provides an ethylene-α-olefin copolymer that has relatively good receptivity to fillers contained as flame retardants while maintaining suitable extrusion processability.

The following describes an embodiment of the present invention, but the present invention is not limited to the following embodiment.

<Ethylene-α-olefin copolymer>
The ethylene-α-olefin copolymer according to this embodiment satisfies all of the following requirements (i) to (iv).
(i) Vicat softening point is 85.0°C or less.
(ii) When the melt torque at 160°C is X [N m] and the melt flow rate is Y [g/10 min], the value of X + 6.5 × Ln(Y) is 23.0 or less.
(iii) When the differential molecular weight distribution curve is divided into three normal distribution curves, the ratio of the sum of the peak heights of the medium molecular weight distribution component (component B) and the high molecular weight component (component C) to the peak height of the low molecular weight component (component A) is 10.00 or more.
(iv) A melt flow rate of 0.10 g/10 min or more and 10.00 g/10 min or less.

The ethylene-α-olefin copolymer according to this embodiment is an ethylene-α-olefin copolymer obtained by copolymerizing ethylene with an α-olefin having 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms 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, and the like, and preferably propylene, 1-butene, or 1-hexene. The above α-olefins having 3 to 20 carbon atoms may be used alone or in combination of two or more kinds.

The ethylene-α-olefin copolymer according to this embodiment may contain at least one α-olefin selected from propylene, butene, and hexene. Examples of such ethylene-α-olefin copolymers include ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-1-hexene copolymers, ethylene-propylene-1-butene copolymers, and ethylene-1-butene-1-hexene copolymers, and preferably ethylene-1-butene copolymers, ethylene-1-hexene copolymers, and ethylene-1-butene-1-hexene copolymers.

The content of monomer units based on ethylene in the ethylene-α-olefin copolymer according to this embodiment is usually 50 to 99% by mass, based on the total mass (100% by mass) of the ethylene-α-olefin copolymer. The content of monomer units based on an α-olefin having 3 to 20 carbon atoms in the ethylene-α-olefin copolymer is usually 1 to 50% by mass, based on the total mass (100% by mass) of the ethylene-α-olefin copolymer.

The Vicat softening point of the ethylene-α-olefin copolymer according to this embodiment is 85.0°C or less (requirement (i)). From the viewpoint of improving filler acceptance, the Vicat softening point is preferably 80.0°C or less.

The Vicat softening point of the ethylene-α-olefin copolymer according to this embodiment is the Vicat softening point (unit: °C) measured by the following method.

[Method of measuring Vicat softening point (unit: °C)]
A sample of the ethylene-α-olefin copolymer is pressed by a hot press to prepare a sheet having a thickness of about 5 mm. The obtained sheet is measured according to the A50 method specified in JIS K7206-1999.

When the melt torque of the ethylene-α-olefin copolymer according to this embodiment at 160°C is X [N m] and the melt flow rate is Y [g/10 min], the value of X + 6.5 × Ln(Y) is 23.0 or less (requirement (ii)). From the viewpoint of improving extrusion processability, the value of X + 6.5 × Ln(Y) is preferably 21.0 or less.

The value of X+6.5×Ln(Y) of the ethylene-α-olefin copolymer according to this embodiment is a value calculated from the melt torque X [unit: N m] and the melt flow rate Y [unit: g/10 min] measured by the following method. Note that Ln indicates the natural logarithm.

[Measuring method for melt torque X [unit: N m]]
The melt torque X is measured under the following conditions using a Labo Plastomill. The apparatus used is a Labo Plastomill 3S150 manufactured by Toyo Seiki Co., Ltd. 38 g of an ethylene-α-olefin copolymer sample is mixed with 400 ppm of an antioxidant Sumilizer GP manufactured by Sumitomo Chemical Co., Ltd., and kneaded for 30 minutes under conditions of a set temperature of 160°C and a screw rotation speed of 60 rpm. Melt torque data during kneading is obtained at 0.125 second intervals, and the average value is calculated for 5 minutes from 25 minutes after the start of kneading to the end of measurement. The obtained average value is defined as the melt torque X.

[Method for measuring melt flow rate Y [g/10 min]]
The melt flow rate Y is measured using a sample of an ethylene-α-olefin copolymer according to Method A defined in JIS K7210-1995 under conditions of a temperature of 190° C. and a load of 2.16 kg.

When the differential molecular weight distribution curve of the ethylene-α-olefin copolymer according to this embodiment is divided into three normal distribution curves, the ratio of the sum of the peak heights of the medium molecular weight distribution component (component B) and the high molecular weight component (component C) to the peak height of the low molecular weight component (component A) is 10.00 or more (requirement (iii)). From the viewpoint of improving filler acceptance, the ratio is preferably 11.00 or more.

The ratio is the ratio of the sum of the peak heights of the medium molecular weight distribution component (component B) and the high molecular weight component (component C) to the peak height of the low molecular weight component (component A), obtained by measuring the differential molecular weight curve (GPC) using the following method and dividing the peaks of the differential molecular weight curve (GPC).

(1) Differential molecular weight distribution curve (GPC)
The molecular weight of the ethylene-α-olefin copolymer sample is measured by the GPC method under the following conditions. Ortho-dichlorobenzene (with 0.1 w/V dibutylhydroxytoluene added as an antioxidant) is used as the solvent, and the sample concentration is 1 mg/mL. For example, Tosoh Corporation's HLC-8121GPC/HT is used as the apparatus. For example, Tosoh Corporation's GPC column, TSKgel GMHHR-H(S)HT 7.5 mm, ID x 300 mm, three columns are used in connection as the measurement column. The mobile phase is ortho-dichlorobenzene (with 0.1 w/V dibutylhydroxytoluene added as an antioxidant), the flow rate is 1 mL/min, the column oven temperature is 140°C, the autosampler temperature is 140°C, and the system oven temperature is 40°C. A refractive index detector (RID) is used as the detector, the RID cell temperature is 140°C, and the sample solution injection amount is 300 μL. The measured value is multiplied by the Q factor value of 41.3 to obtain the polystyrene equivalent molecular weight (M).

(2) Peak Division of Differential Molecular Weight Distribution Curve Peak division of a differential molecular weight distribution curve can be performed using, for example, Python, and specifically, is performed by the method shown below.

The first step is to download the Anaconda version of the corresponding model, install it, and configure the environment.

In the second step, give the first column of the electronic data for the differential molecular weight distribution curve "x" the title and the second column "y". Next, enter the logM value after the second line in the first column, and dwt/d(logM) after the second line in the second column, and save as a csv file ('data name.csv').

In the third step, use Jupyter Notebook (Anaconda3) to enter and execute the code shown below.

#Loading modules
from scipy.optimize import curve_fit
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.cm as cm
import pandas as pd

# Enter data
dataset = pd.read_csv('data name.csv')
x = dataset['x']
y = dataset['y']

#Define the fitting function
def func(x, *params):

# Determine the number of functions to fit based on the length of params
num_func = int(len(params)/3)

# Insert each parameter into the Gaussian function and add it to y_list
y_list = []
for i in range(num_func):
y = np.zeros_like(x)
param_range = list(range(3*i,3*(i+1),1))
amp = params[int(param_range[0])]
ctr = params[int(param_range[1])]
wid = params[int(param_range[2])]
y = y + amp * np.exp( -((x - ctr)/wid)**2)
y_list.append(y)

# Overlay all the Gaussian functions in y_list
y_sum = np.zeros_like(x)
for i in y_list:
y_sum = y_sum + i

# Add background
y_sum = y_sum + params[-1]
return y_sum

# Define the Gaussian function used for fitting: y = amp*exp[-((x-ctr)/wid)^2]
# amp = 1/(sqrt(2pi)*sig), ctr = m, wid = 2sig
def fit_plot(x, *params):
num_func = int(len(params)/3)
y_list = []
for i in range(num_func):
y = np.zeros_like(x)
param_range = list(range(3*i,3*(i+1),1))
amp = params[int(param_range[0])]
ctr = params[int(param_range[1])]
wid = params[int(param_range[2])]
y = y + amp * np.exp( -((x - ctr)/wid)**2) + params[-1]
y_list.append(y)
return y_list

#Setting initial values
# guess.appen([amp,ctr,wid]) --> amp: height, ctr: center value, wid: width
#If any of the following apply, change the initial values of "Amp", "Center", and "Width" until the condition no longer applies.
#If you get a Runtime Error
#When any one or more of Amp, Center, and Width is a negative value
#If the absolute value of Baseline is greater than 3
guess = []
guess.append([initial value of "Amp", initial value of "Center", initial value of "Width"]) # 1st curve
guess.append([initial value of "Amp", initial value of "Center", initial value of "Width"]) # 2nd curve
guess.append([initial value of "Amp", initial value of "Center", initial value of "Width"]) # 3rd curve

# Initial background value
background = 0.1

# Combining initial value lists
guess_total = []
for i guess:
guess_total.extend(i)
guess_total.append(background)

# Fitting Assign optimized parameters to popt
popt, pcov = curve_fit(func, x, y, p0=guess_total)

# Plotting experimental and optimization data
fit = func(x, *popt)
plt.figure(figsize=(8,5))
plt.scatter(x, y, marker="o", s=50, c="blue")
plt.plot(x, fit , ls='-', c='red', lw=3)

# Plot each curve
y_list = fit_plot(x, *popt)
baseline = np.zeros_like(x) + popt[-1]
for n, i in enumerate(y_list):
plt.fill_between(x, i, baseline, facecolor=cm.rainbow(n/len(y_list)), alpha=0.7)

# List of parameters, Baseline is added to the whole
data = {
"C1" : popt[0:3],
"C2" : popt[3:6],
"C3" : popt[6:9],
"Baseline" : popt[9:10],
}

# Display parameters in list format
idx = ["Amp","Center","Width"]
df = pd.DataFrame(data, index=idx)
df

[Peak height ratio [unit: none]]
The three peak center values ("Center") obtained by the above method are designated, in order from the smallest, as component A, component B, and component C, and the ratio of the sum of the peak heights of components B and C to the peak height ("Amp") of component A is calculated.

The melt flow rate of the ethylene-α-olefin copolymer according to this embodiment is 0.10 g/10 min or more and 10.00 g/10 min or less (requirement (iv)). From the viewpoint of improving extrusion processability, the melt flow rate is preferably 0.20 g/10 min or more and 10.00 g/10 min or less.

The melt flow rate of the ethylene-α-olefin copolymer according to this embodiment is a value obtained by measuring a sample of the ethylene-α-olefin copolymer at a temperature of 190°C and a load of 2.16 kg according to Method A specified in JIS K7210-1995.

The ethylene-α-olefin copolymer according to this embodiment preferably has long chain branches. Examples of the ethylene-α-olefin copolymer include those having a high flow activation energy (Ea) of typically 40 kJ/mol or more. From the viewpoint of improving the appearance of the extrusion molded product, the flow activation energy (Ea) is preferably 45 kJ/mol or more, more preferably 50 kJ/mol or more, and even more preferably 60 kJ/mol or more. Furthermore, from the viewpoint of improving the mechanical strength of the extrusion molded product, the flow activation energy (Ea) is preferably 100 kJ/mol or less, more preferably 90 kJ/mol or less.

The activation energy (Ea) of flow of ethylene-α-olefin copolymer is a value calculated by the Arrhenius equation from the shift factor (aT) when creating a master curve showing the angular frequency (unit: rad/sec) dependence of the melt complex viscosity (unit: Pa sec) at 190°C based on the temperature-time superposition principle, and is a value obtained by the method shown below. That is, for four temperatures including 190°C out of the temperatures of 130°C, 150°C, 170°C, 190°C, and 210°C, the melt complex viscosity-angular frequency curve of the ethylene-α-olefin copolymer at each temperature (T, unit: °C) (the unit of the melt complex viscosity is Pa·sec, and the unit of the angular frequency is rad/sec.) is superimposed on the melt complex viscosity-angular frequency curve of the ethylene copolymer at 190°C for each melt complex viscosity-angular frequency curve at each temperature (T) based on the temperature-time superposition principle, and the shift factor (aT) at each temperature (T) is calculated by the least squares method from each temperature (T) and the shift factor (aT) at each temperature (T), and the linear approximation formula (formula (I) below) of [Ln(aT)] and [1/(T+273.16)] is calculated. Next, Ea is calculated from the slope m of the linear formula and the following formula (II).

Ln(aT)=m(1/(T+273.16))+n (I)
Ea = |0.008314 × m| (II)

In the formulas (I) and (II), aT, Ea, and T represent the following.
aT: Shift factor Ea: Activation energy of flow (unit: kJ/mol)
T: Temperature (unit: °C)

The above calculation may be performed using commercially available calculation software. Examples of the calculation software include Rhios V. 4.4.4 manufactured by Rheometrics. The shift factor (aT) is the amount of movement when the double logarithmic curve of melt complex viscosity-angular frequency at each temperature (T) is shifted in the log(Y) = -log(X) axis direction (where the Y axis is melt complex viscosity and the X axis is angular frequency) and superimposed on the melt complex viscosity-angular frequency curve at 190°C. In this superposition, the double logarithmic curve of melt complex viscosity-angular frequency at each temperature (T) is shifted by aT times in angular frequency and by 1/aT times in melt complex viscosity. In addition, when the shift factor at four temperatures including 190°C among 130°C, 150°C, 170°C, 190°C, and 210°C is calculated by the least squares method to obtain the linear approximation formula (I) obtained from the temperature, the correlation coefficient is usually 0.99 or more.

The above melt complex viscosity-angular frequency curve is measured using a viscoelasticity measuring device (e.g., Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics, etc.) under the following conditions: geometry: parallel plate, plate diameter: 25 mm, plate spacing: 1.5 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 to preliminarily mix an appropriate amount of antioxidant (e.g., 1000 ppm) into the measurement sample.

The melt flow rate ratio (MFRR) of the ethylene-α-olefin copolymer according to this embodiment is usually 40 to 300. The MFRR is preferably 50 or more, more preferably 60 or more, from the viewpoint of improving the appearance of the extrusion molded article. The MFRR is preferably 250 or less, more preferably 200 or less, from the viewpoint of improving the mechanical strength of the extrusion molded article. The MFRR is a value obtained by dividing the melt flow rate (MFR-H, unit: g/10 min) measured under conditions of a load of 21.6 kg and a measurement temperature of 190°C according to the A method specified in JIS K7210-1995, by the melt flow rate (MFR) measured under conditions of a load of 2.16 kg and a temperature of 190°C according to the A method specified in JIS K7210-1995.

The density of the ethylene-α-olefin copolymer according to this embodiment is usually 870 to 960 kg/m ^3. From the viewpoint of enhancing the mechanical strength of the extrusion molded product, the density is preferably 940 kg/m ³ or less, more preferably 930 kg/m ³ or less, even more preferably 925 kg/m ³ or less, and particularly preferably 920 kg/m ³ or less. From the viewpoint of enhancing the heat resistance of the extrusion molded product, the density is preferably 880 kg/m ³ or more, more preferably 890 kg/m ³ or more. The density is measured according to the method specified in JIS K7112-1980.

<Method of producing ethylene-α-olefin copolymer>
The method for producing an ethylene-α-olefin copolymer according to the present embodiment is a method for producing an ethylene-α-olefin copolymer having a density of 911 kg/ ^m3 or less by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of an olefin polymerization catalyst, and the polymerization conditions are adjusted so that A defined in the following formula (1) is 67.0 or more and 100.0 or less.

In recent years, with the decrease in density of ethylene-α-olefin copolymers, there is a problem that poor flow of the polymer occurs in a polymerization tank when producing an ethylene-α-olefin copolymer, resulting in failure to operate stably. Therefore, it is required to suppress the formation of lumps due to adhesion and melting of polymer particles, which may cause the poor flow, and to suppress the scattering of polymer particles from the top of the polymerization tank in terms of improving the catalyst consumption rate. In the method for producing an ethylene-α-olefin copolymer according to this embodiment, even if the density of the ethylene-α-olefin copolymer is as low as 911 kg/m ³ or less, by adjusting the polymerization conditions so that A defined in the above formula (1) is 67.0 or more and 100.0 or less, the scattering of polymer particles can be suppressed, and the formation of lumps due to adhesion and melting of polymer particles can be suppressed, making it relatively difficult for poor flow to occur.

A defined in the above formula (1) is preferably 75.0 or more and 98.0 or less. A defined in the above formula (1) can be adjusted to a predetermined range by adjusting the concentration of α-olefins having 3 to 20 carbon atoms, the concentration of alkanes, the concentration of ethylene, and the concentration of gases other than hydrocarbons in the polymerization reaction gas, as well as the polymerization temperature.

The density of the ethylene-α-olefin copolymer may be, for example, 889 kg/m ³ or more and 911 kg/m ³ or less.

In the above formula (1), the number of short chain branches of the ethylene-α-olefin copolymer is preferably 21.0 or more, and more preferably 25.0 or more, per 1,000 carbon atoms, from the viewpoint of making flow defects relatively unlikely to occur. The number of short chain branches of the ethylene-α-olefin copolymer may be, for example, 33.0 or less.

[Method for measuring number of short chain branches]
The number of short chain branches of the ethylene-α-olefin copolymer can be measured by the following method.

< ^13C -NMR measurement of standard product>
The carbon nuclear magnetic resonance ( ¹³ C-NMR) spectrum of the standard is measured under the following measurement conditions.
(Measurement condition)
Apparatus: AVANCE600 manufactured by Bruker
Measurement probe: 10 mm cryoprobe Measurement solvent: 1,2-dichlorobenzene-d4
Measurement temperature: 135°C
Measurement method: Proton decoupling method Pulse width: 45 degrees Pulse repetition time: 4 seconds Window function: negative exponential function and Gaussian function Number of accumulations: 5000

<Number of short chain branches of standard product>
The obtained carbon nuclear magnetic resonance ( ¹³ C-NMR) spectrum is analyzed using an exponential function, and the sum of the peak areas of all peaks having peak tops at 5 to 50 ppm is set to 1000. The peak area derived from a methine carbon bonded to a branch having two carbon atoms is calculated as the amount of short chain branches.

<Infrared spectroscopy measurement>
For example, as described in "New Polymer Analysis Handbook, First Edition, p. 590, edited by the Japan Analytical Chemistry Association," it is known that short chain branches of ethylene-α-olefin copolymers are observed to have a peak at 1378 cm ^-1 in infrared spectroscopy. The ethylene-α-olefin copolymer is heated at 6 MPa for 5 minutes using a heat press preheated at 150° C. for 5 minutes, and then cooled in a water-cooled mold for 5 minutes to be molded to a thickness of 0.01 cm. The thickness after molding is measured with a thickness meter. The infrared spectroscopy spectrum of the molded ethylene-α-olefin copolymer is measured under the following measurement conditions. The infrared spectroscopy spectrum of the standard sample for which 13C-NMR was measured is also measured using the same procedure.

(Measurement condition)
Apparatus: FTIR470plus manufactured by JASCO Corporation
Detector: TGS
Number of scans: 16 Resolution: 2 cm ^-1
Vertical axis: absorbance

<Number of short chain branches>
In the obtained infrared spectrum, a straight line is drawn between 955 cm ⁻¹ and 1790 cm ⁻¹ to form a baseline. The number of short chain branches B is calculated by the formula (i).
B = Bs × F / Fs Formula (i)
Here, Bs is the number of short chain branches determined by 13C-NMR of a standard product, F is given by formula (ii), and Fs is given by formula (iii).
F = (A1 / (ρ × t) - 0.95A2 / (ρ × t) + 3.8) Formula (ii)
Fs = (A1s / (ρs × ts) - 0.95A2 / (ρs × ts) + 3.8) Formula (iii)
Here, A1 is the height from the baseline at 1378 cm ^-1 in the infrared spectrum of the ethylene-α-olefin copolymer, ρ is the density of the ethylene-α-olefin copolymer (g/cm ³ ), t is the measured thickness of the ethylene-α-olefin copolymer (cm), A2 is the maximum height in the range of 1281 to 1324 cm ^-1 in the infrared spectrum of the ethylene-α-olefin copolymer after baseline subtraction, A1s is the height from the baseline at 1378 cm ^-1 in the infrared spectrum of the standard, ρs is the density of the standard (g/cm ³ ), ts is the measured thickness of the standard, and A2s is the maximum height in the range of 1281 to 1324 cm ^-1 in the infrared spectrum of the standard after baseline subtraction.

The method for producing the ethylene-α-olefin copolymer according to this embodiment may, for example, be a method of copolymerizing ethylene and an α-olefin in the presence of an olefin polymerization catalyst using as catalyst components: a solid particulate cocatalyst component (hereinafter sometimes referred to as "component (A)") in which a cocatalyst component such as an organoaluminum compound, an organoaluminum oxy compound, a boron compound, or an organozinc compound is supported on a particulate carrier; and a metallocene complex (hereinafter sometimes referred to as "component (B)") having a ligand having a structure in which two cyclopentadienyl-type anion skeletons are bonded by a bridging group such as an alkylene group or a silylene group. In one embodiment, the olefin polymerization catalyst is a polymerization catalyst that uses as catalyst components: a solid particulate cocatalyst component in which at least one cocatalyst component selected from an organoaluminum compound, an organoaluminum oxy compound, a boron compound, and an organozinc compound is supported on a particulate carrier; and a metallocene complex having a ligand having a structure in which two cyclopentadienyl-type anion skeletons are bonded by at least one bridging group selected from an alkylene group and a silylene group.

Examples of the solid particulate promoter component include a component in which methylalumoxane is mixed with porous silica, and a component in which diethylzinc, water, and fluorinated phenol are mixed with porous silica.

Specific examples of the solid particulate promoter component include a promoter support component (A) obtained by contacting component (a) diethyl zinc, component (b) fluorinated phenol, component (c) water, component (d) porous silica, and component (e) trimethyldisilazane ((( _CH3 ) _3Si ) _2NH ).

Examples of the fluorinated phenol of component (b) include pentafluorophenol, 3,5-difluorophenol, 3,4,5-trifluorophenol, and 2,4,6-trifluorophenol. From the viewpoint of increasing the flow activation energy (Ea) and molecular weight distribution (Mw/Mn) of the ethylene-α-olefin copolymer according to this embodiment, it is preferable to use two types of fluorinated phenols having different numbers of fluorine atoms. In this case, the molar ratio of the phenol having a larger number of fluorine atoms to the phenol having a smaller number of fluorine atoms is usually 20/80 to 80/20. The molar ratio is preferably 30/70 to 70/30.

Regarding the amounts of the components (a), (b) and (c) used, it is preferable that, assuming that the molar ratio of the amounts of the components used is component (a):component (b):component (c)=1:y:z, y and z satisfy the following formula:

|2-y-2z|≦1
In the above formula, y is preferably a number from 0.01 to 1.99, more preferably a number from 0.10 to 1.80, even more preferably a number from 0.20 to 1.50, and particularly preferably a number from 0.30 to 1.00.

The amount of component (d) used relative to component (a) is preferably an amount such that the number of moles of zinc atoms contained in the particles obtained by contacting component (a) with component (d) is 0.1 mmol or more, more preferably 0.5 to 20 mmol, per 1 g of the particles. The amount of component (e) used relative to component (d) is preferably an amount such that the number of moles of component (e) is 0.1 mmol or more, more preferably 0.5 to 20 mmol, per 1 g of component (d).

Examples of the metallocene complex include a zirconocene complex in which two indenyl groups are bonded with an ethylene group, a dimethylmethylene group, or a dimethylsilylene group, a zirconocene complex in which two methylindenyl groups are bonded with an ethylene group, a dimethylmethylene group, or a dimethylsilylene group, a zirconocene complex in which two methylcyclopentadienyl groups are bonded with an ethylene group, a dimethylmethylene group, or a dimethylsilylene group, and a zirconocene complex in which two dimethylcyclopentadienyl groups are bonded with an ethylene group, a dimethylmethylene group, or a dimethylsilylene group. Examples of the metal atom of component (ii) include zirconium and hafnium, and examples of the remaining substituents that the metal atom has include a diphenoxy group and a dialkoxy group. Component (ii) is preferably ethylenebis(1-indenyl)zirconium diphenoxide.

In the polymerization catalyst using the above-mentioned solid particulate cocatalyst component and metallocene complex, an organoaluminum compound may be used in combination as a catalyst component, as appropriate. Examples of the organoaluminum compound include triisobutylaluminum and tri-normal octylaluminum.

The amount of the metallocene complex used is preferably 5×10 ⁻⁶ to 5×10 ⁻⁴ mol per 1 g of the solid particulate cocatalyst component, and the amount of the organoaluminum compound used is preferably an amount such that the amount of aluminum atoms of the organoaluminum compound is 1 to 2000 mol per 1 mol of metal atoms of the metallocene complex.

In addition, in the polymerization catalyst using the above-mentioned solid particulate cocatalyst component and metallocene complex, an electron donor compound may be used as a catalyst component. Examples of the electron donor compound include triethylamine and tri-normal octylamine.

When two types of fluorinated phenols with different numbers of fluorines are used as the fluorinated phenol of component (b), an electron donor compound is preferably used.

The amount of the electron donor compound used is usually 0.1 to 10 mol % based on the number of moles of aluminum atoms in the organoaluminum compound used as the catalyst component. From the viewpoint of increasing the molecular weight distribution (Mw/Mn) of the ethylene-α-olefin copolymer according to this embodiment, the amount used is preferably 0.2 to 5 mol % based on the number of moles of aluminum atoms in the organoaluminum compound used as the catalyst component.

More specifically, the method for producing the ethylene-α-olefin copolymer according to this embodiment includes a method of copolymerizing ethylene with an α-olefin having 3 to 20 carbon atoms in the presence of a catalyst obtained by contacting the cocatalyst support component (a), a crosslinked bisindenyl zirconium complex, and an organoaluminum compound.

The polymerization method may be, for example, a continuous polymerization method involving the formation of particles of an ethylene-α-olefin copolymer. The continuous polymerization method may be, for example, continuous gas-phase polymerization, continuous slurry polymerization, or continuous bulk polymerization, with continuous gas-phase polymerization being preferred. The gas-phase polymerization reactor is usually an apparatus having a fluidized bed reactor, and is preferably an apparatus having a fluidized bed reactor with an enlarged section. The apparatus having a fluidized bed reactor may have an agitator installed in the reactor.

The methods for supplying each component of the polymerization catalyst used in the production of the ethylene-α-olefin copolymer according to this embodiment to the reaction vessel usually include a method of supplying them in a moisture-free state using an inert gas such as nitrogen or argon, hydrogen, ethylene, etc., or a method of dissolving or diluting each component in a solvent and supplying them in a solution or slurry state. Each component of the polymerization catalyst may be supplied separately, or any component may be supplied after contacting in advance in any order.

Also, a prepolymerization may be carried out before carrying out the main polymerization. The prepolymerized prepolymerization catalyst component is preferably used as a catalyst component or catalyst for the main polymerization. Different α-olefins may be used in the main polymerization and the prepolymerization. The α-olefin prepolymerized with ethylene is preferably an α-olefin having 4 to 12 carbon atoms, more preferably an α-olefin having 6 to 8 carbon atoms.

In the above formula (1), the polymerization temperature is usually lower than the temperature at which the ethylene-α-olefin copolymer melts, and is preferably 0°C or higher and 150°C or lower, more preferably 30°C or higher and 100°C or lower, even more preferably 50°C or higher and 90°C or lower, and particularly preferably 66°C or higher and 84°C or lower. In addition, from the viewpoint of broadening the molecular weight distribution (Mw/Mn) of the ethylene-α-olefin copolymer, the polymerization temperature is preferably 60°C or higher and 85°C or lower.

The polymerization time (average residence time in the case of a continuous polymerization reaction) is usually 1 to 20 hours. From the viewpoint of widening the molecular weight distribution (Mw/Mn) of the ethylene-α-olefin copolymer, the polymerization time (average residence time) is preferably 2 to 10 hours.

In the above formula (1), the concentration of α-olefins having 3 to 20 carbon atoms in the polymerization reaction gas is preferably 1.0 mol% or more and 2.5 mol% or less, more preferably 1.3 mol% or more and 2.1 mol% or less. The alkane concentration is preferably 0.1 mol% or more and 5.0 mol% or less, more preferably 0.3 mol% or more and 3.0 mol% or less. The ethylene concentration is preferably 65.0 mol% or more and 95.0 mol% or less, more preferably 70.0 mol% or more and 90.0 mol% or less.

When producing an ethylene-α-olefin copolymer, hydrogen may be added to the polymerization reaction gas as a molecular weight regulator, and an inert gas (e.g., nitrogen) may be allowed to coexist in the polymerization reaction gas in order to prevent poor flow of the polymer in the polymerization tank. In one embodiment, when hydrogen and nitrogen are contained in the polymerization reaction gas, the concentration of gases other than hydrocarbons in the polymerization reaction gas in the above formula (1) is the sum of the hydrogen concentration and the nitrogen concentration. In this embodiment, the nitrogen concentration is 5.0 mol% or more and 30.0 mol% or less, and preferably 10.0 mol% or more and 25.0 mol% or less. In this embodiment, the hydrogen concentration is preferably 0.3 mol% or more and 2.5 mol% or less, and more preferably 0.5 mol% or more and 1.5 mol% or less.

The molar concentration of hydrogen in the polymerization reaction gas relative to the molar concentration of ethylene in the polymerization reaction gas is usually 0.1 mol% or more and 3 mol% or less, with the molar concentration of ethylene in the polymerization reaction gas taken as 100 mol%. In addition, from the viewpoint of widening the molecular weight distribution (Mw/Mn) of the ethylene-α-olefin copolymer, the molar concentration of hydrogen in the polymerization reaction gas is preferably 0.2 mol% or more and 2.5 mol% or less, with the molar concentration of ethylene in the polymerization reaction gas taken as 100 mol%.

The ethylene-α-olefin copolymer according to this embodiment may contain additives as necessary. Hereinafter, the ethylene-α-olefin copolymer containing additives is referred to as a polyethylene resin composition. The polyethylene resin composition contains the ethylene-α-olefin copolymer according to this embodiment in an amount of preferably 5% by mass or more and 95% by mass or less, more preferably 10% by mass or more and 90% by mass or less, and even more preferably 15% by mass or more and 85% by mass or less, based on the total amount of the polyethylene resin composition being 100% by mass.

Examples of the additives include organic peroxides, hindered amine light stabilizers, crosslinking assistants, ultraviolet absorbers, silane coupling agents, etc.

(1) Organic Peroxide The polyethylene resin composition may contain an organic peroxide. The organic peroxide is mainly used to crosslink the polyethylene resin. As the organic peroxide, an organic peroxide having a decomposition temperature (temperature at which the half-life is 1 hour) of 70 to 180°C, particularly 90 to 160°C, may be used. Examples of such organic peroxides include t-butylperoxyisopropyl carbonate, t-butylperoxy-2-ethylhexyl carbonate, t-butylperoxyacetate, t-butylperoxybenzoate, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3,1,1-di(t-butylperoxy)-3,4 ... , 3,5-trimethylcyclohexane, 1,1-di(t-butylperoxy)cyclohexane, methyl ethyl ketone peroxide, 2,5-dimethylhexyl-2,5-diperoxybenzoate, t-butyl hydroperoxide, p-menthane hydroperoxide, benzoyl peroxide, p-chlorobenzoyl peroxide, t-butylperoxyisobutyrate, hydroxyheptyl peroxide, dicyclohexanone peroxide, and the like.

The blending ratio of the organic peroxide is preferably 0.2 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, and even more preferably 1 to 2 parts by mass, per 100 parts by mass of the ethylene-α-olefin copolymer according to this embodiment. When the blending ratio of the organic peroxide is within the above range, crosslinking of the polyethylene resin is carried out sufficiently and uniformly.

(2) Hindered amine light stabilizer The polyethylene resin composition may contain a hindered amine light stabilizer. The hindered amine light stabilizer captures radical species harmful to the polymer and prevents new radicals from being generated. There are many types of hindered amine light stabilizers, ranging from low molecular weight compounds to high molecular weight compounds, and any conventionally known compounds may be used without any particular limitations.

Low molecular weight hindered amine light stabilizers include a mixture of 70% by weight of decanedioic acid bis(2,2,6,6-tetramethyl-1(octyloxy)-4-piperidinyl)ester, a reaction product of 1,1-dimethylethyl hydroperoxide and octane (molecular weight 737) and 30% by weight of polypropylene; bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate (molecular weight 685); a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidylsebacate (molecular weight 509); bis(2,2,6,6-tetramethyl-4-piperidyl) diethyl) sebacate (molecular weight 481); tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4-butane tetracarboxylate (molecular weight 791); tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butane tetracarboxylate (molecular weight 847); a mixture of 2,2,6,6-tetramethyl-4-piperidyl-1,2,3,4-butane tetracarboxylate and tridecyl-1,2,3,4-butane tetracarboxylate (molecular weight 900); a mixture of 1,2,2,6,6-pentamethyl-4-piperidyl-1,2,3,4-butane tetracarboxylate and tridecyl-1,2,3,4-butane tetracarboxylate (molecular weight 900), etc.

Examples of high molecular weight hindered amine light stabilizers include poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}] (molecular weight 2,000 to 3,100); polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (molecular weight 3,100 to 4,000); N,N',N",N"'-tetrakis-(4,6-bis a mixture of -(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine (molecular weight 2,286) and the polymer of the above-mentioned dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol; a mixture of dibutylamine-1,3,5-triazine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine; Compounds (molecular weight 2,600 to 3,400), as well as 4-acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-acryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1-propyl-2,2,6,6-tetramethylpiperidine, 4-acryloyloxy-1-butyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-2,2,6,6-tetramethylpiperidine, Examples of the copolymer include copolymers of cyclic aminovinyl compounds and ethylene such as oxy-1,2,2,6,6-pentamethylperidine, 4-methacryloyloxy-1-ethyl-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1-butyl-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and 4-crotonoyloxy-1-propyl-2,2,6,6-tetramethylpiperidine. The above hindered amine light stabilizers may be used alone or in combination of two or more.

Among these, the hindered amine light stabilizer is preferably poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}] (molecular weight 2,000 to 3,100); polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol (molecular weight 3,100 to 4,000); N,N',N",N"'-tetrakis-(4,6-bis-(butyl-(N-methyl-2,2,6,6-tetramethylpiperidin-4-yl)amino)-triazin-2-yl)-4,7-diazadecane-1,10-diamine (molecular weight A mixture of dimethyl succinate (molecular weight 2,286) and the above-mentioned polymer of dimethyl succinate and 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol; a polycondensate of dibutylamine-1,3,5-triazine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine (molecular weight 2,600 to 3,400); a copolymer of a cyclic aminovinyl compound and ethylene is used. This is because bleeding out of the hindered amine light stabilizer over time during use of the product is prevented. In addition, from the viewpoint of ease of preparation of the polyethylene resin composition, the hindered amine light stabilizer preferably has a melting point of 60°C or higher.

In the polyethylene resin composition, the content of the hindered amine-based light stabilizer is preferably 0.01 to 2.5 parts by mass, more preferably 0.01 to 1.0 parts by mass, even more preferably 0.01 to 0.5 parts by mass, particularly preferably 0.01 to 0.2 parts by mass, and most preferably 0.03 to 0.1 parts by mass, relative to 100 parts by mass of the ethylene-α-olefin copolymer.

By making the content of the hindered amine-based light stabilizer 0.01 parts by mass or more, a sufficient stabilizing effect can be obtained, and by making it 2.5 parts by mass or less, discoloration of the resin due to excessive addition of the hindered amine-based light stabilizer can be suppressed. Furthermore, in the polyethylene resin composition, the mass ratio of the organic peroxide to the hindered amine-based light stabilizer is preferably 1:0.01 to 1:10, and more preferably 1:0.02 to 1:6.5. This makes it possible to significantly suppress yellowing of the resin.

(3) Crosslinking Auxiliary Agent The polyethylene resin composition may contain a crosslinking auxiliary agent. The crosslinking auxiliary agent is effective in promoting the crosslinking reaction and increasing the degree of crosslinking of the ethylene-α-olefin copolymer. Specific examples of the crosslinking auxiliary agent include polyallyl compounds and poly(meth)acryloxy compounds. More specifically, examples of the crosslinking auxiliary agent include polyallyl compounds such as triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diallyl fumarate, and diallyl maleate, poly(meth)acryloxy compounds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate, and divinylbenzene. The crosslinking auxiliary agent may be blended in an amount of about 0 to 5 parts by mass relative to 100 parts by mass of the ethylene-α-olefin copolymer according to this embodiment.

(4) Ultraviolet Absorber The polyethylene resin composition may contain an ultraviolet absorber. Examples of the ultraviolet absorber include various types of ultraviolet absorbers such as benzophenone-based, benzotriazole-based, triazine-based, and salicylic acid ester-based.

Examples of benzophenone-based ultraviolet absorbers include 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-n-octadecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2,4-dihydroxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2,2',4,4'-tetrahydroxybenzophenone.

Benzotriazole-based UV absorbers include hydroxyphenyl-substituted benzotriazole compounds such as 2-(2-hydroxy-5-methylphenyl)benzotriazole, 2-(2-hydroxy-5-t-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-dimethylphenyl)benzotriazole, 2-(2-methyl-4-hydroxyphenyl)benzotriazole, 2-(2-hydroxy-3-methyl-5-t-butylphenyl)benzotriazole, 2-(2-hydroxy-3,5-di-t-amylphenyl)benzotriazole, and 2-(2-hydroxy-3,5-di-t-butylphenyl)benzotriazole. Examples of triazine-based UV absorbers include 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol and 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-(hexyloxy)phenol. Examples of salicylic acid ester-based UV absorbers include phenyl salicylate and p-octylphenyl salicylate. The content of these UV absorbers is preferably 2.0 parts by mass or less, more preferably 0.05 to 2.0 parts by mass, even more preferably 0.1 to 1.0 parts by mass, particularly preferably 0.1 to 0.5 parts by mass, and most preferably 0.2 to 0.4 parts by mass, relative to 100 parts by mass of the ethylene-α-olefin copolymer.

(5) Silane Coupling Agent A silane coupling agent can be used in the polyethylene resin composition for the purpose of modifying the resin. Examples of the silane coupling agent used in the polyethylene resin composition include γ-chloropropyltrimethoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, vinyl-tris-(β-methoxyethoxy)silane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, and 3-acryloxypropyltrimethoxysilane. The silane coupling agent is preferably vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, or 3-acryloxypropyltrimethoxysilane. The amount of these silane coupling agents used is preferably 0 to 5 parts by mass, more preferably 0.01 to 4 parts by mass, even more preferably 0.01 to 2 parts by mass, and particularly preferably 0.05 to 1 part by mass, based on 100 parts by mass of the ethylene-α-olefin copolymer.

(6) Other Additives The polyethylene resin composition may contain other optional additives as long as the additives do not significantly impair the object of the present invention. Examples of such optional additives include antioxidants, crystal nucleating agents, clarifying agents, lubricants, colorants, dispersants, fillers, fluorescent whitening agents, ultraviolet absorbers, light stabilizers, and the like that are commonly used in polyolefin resin materials.

In addition, in order to impart flexibility, etc., the polyethylene resin composition may be blended with 3 to 75 parts by mass of a rubber-based compound, such as a lubricating oil, a crystalline ethylene-α-olefin copolymer polymerized with a Ziegler or metallocene catalyst, and/or an ethylene-α-olefin elastomer such as EBR or EPR, or a styrene-based elastomer such as SEBS or a hydrogenated styrene block copolymer, within a range that does not impair the object of the present invention. Furthermore, in order to impart melt tension, etc., 3 to 75 parts by mass of a high-pressure low-density polyethylene may be blended.

Methods for blending other optional additional components with the polyethylene resin composition include known melt-kneading methods. Examples of such methods include a method of dry blending using a tumbler blender, Henschel mixer, or the like, followed by melt-kneading using a single-screw extruder, multi-screw extruder, or the like, and a method of melt-kneading using a kneader, Banbury mixer, or the like.

The ethylene-α-olefin copolymer according to this embodiment or a resin composition in which the ethylene-α-olefin copolymer according to this embodiment is blended with other optional additional components can be used, for example, insulators such as sheets, containers, electric wires and cables, sheaths, solar cell encapsulants, etc.

A known molding method can be used to mold the ethylene-α-olefin copolymer according to this embodiment or a resin composition in which the ethylene-α-olefin copolymer according to this embodiment is blended with other optional additional components into various molded articles. Known molding methods include, for example, extrusion molding and coated extrusion molding for coating electric wires and pipes.

[Solar Cell Encapsulant and Solar Cell]
The ethylene-α-olefin copolymer according to the present embodiment or the resin composition in which the ethylene-α-olefin copolymer according to the present embodiment is blended with other optional additional components can be used for a solar cell encapsulant (hereinafter, also simply referred to as "encapsulant"). The solar cell encapsulant is the ethylene-α-olefin copolymer according to the present embodiment or the polyethylene resin composition formed into pellets or sheets. By using this solar cell encapsulant, a solar cell module can be manufactured by fixing a solar cell element together with upper and lower protective materials. Examples of such solar cell modules include those having a configuration in which a solar cell element is sandwiched between encapsulants from both sides, such as upper transparent protective material/encapsulant/solar cell element/encapsulant/lower protective material; those having a configuration in which an encapsulant and an upper transparent protective material are formed on a solar cell element formed on the inner peripheral surface of a lower substrate protective material; and those having a configuration in which an encapsulant and a lower protective material are formed on a solar cell element formed on the inner peripheral surface of an upper transparent protective material, for example, a fluororesin-based transparent protective material on which an amorphous solar cell element is formed by sputtering or the like.

The solar cell element is not particularly limited, and various solar cell elements can be used, including silicon-based elements such as single crystal silicon, polycrystalline silicon, and amorphous silicon, and III-V and II-VI compound semiconductor elements such as gallium-arsenide, copper-indium-selenium, and cadmium-tellurium. In the present invention, glass is preferably used as the substrate.

Examples of the upper protective material constituting the solar cell module include glass, acrylic resin, polycarbonate, polyester, and fluorine-containing resin. Examples of the lower protective material include single or multi-layer sheets of metals and various thermoplastic resin films, such as metals such as tin, aluminum, and stainless steel, inorganic materials such as glass, and single-layer or multi-layer protective materials such as polyester, inorganic vapor-deposited polyester, fluorine-containing resin, and polyolefin. Such upper and/or lower protective materials can be treated with a primer to improve adhesion to the sealing material. In the present invention, glass is preferably used as the upper protective material.

The solar cell encapsulant may be used as pellets, but is usually formed into a sheet having a thickness of about 0.1 to 1 mm. If the thickness of the solar cell encapsulant is within the above range, the strength can be increased, adhesion can be sufficient, and transparency can be maintained. The thickness is preferably 0.25 to 0.6 mm. If the thickness of the sheet-shaped solar cell encapsulant is 0.25 mm or more, it can sufficiently absorb impact, and even if it is thinned to, for example, about 0.25 mm, it can have molding properties and heat resistance at a sufficiently preferable level. Also, if the thickness is 0.6 mm or less, the impact absorbing effect is sufficient, it can meet the demand for thin solar cell modules, and is economical.

The sheet-shaped solar cell encapsulant may be a multilayer sheet having a skin layer-core layer-skin layer structure. The skin layer is formed on the outermost surface of the sheet-shaped solar cell encapsulant, and is preferably a layer having a relatively low density and a low melting point. The core layer is preferably a layer having a relatively high density and a high melting point. The ethylene-α-olefin copolymer according to this embodiment may be used in the skin layer or the core layer of the sheet-shaped solar cell encapsulant. The ethylene-α-olefin copolymer according to this embodiment may be used in both the skin layer and the core layer.

When the sheet-shaped solar cell encapsulant is a multi-layer sheet having a skin layer-core layer-skin layer structure, the core layer does not need to contain a crosslinking agent or crosslinking assistant.

The core layer may contain a silane-modified polyethylene resin. When a silane-modified polyethylene resin is added to the core layer, the silane-modified polyethylene resin may have a mass average molecular weight of 70,000 or more in terms of polystyrene and a melting point of about 90°C. In the sheet-shaped solar cell encapsulant, the silane-modified polyethylene resin preferably acts as an intermediate melting point resin component.

The density of the encapsulant composition for the core layer is preferably 0.905 g/cm ³ or more and 0.925 g/cm ³ or less, and more preferably 0.910 g/cm ³ or more and 0.920 g/cm ³ or less.

The melting point of the encapsulant composition for the core layer is preferably 70°C or more and 110°C or less, more preferably 80°C or more and 100°C or less. By maintaining the melting point of the encapsulant composition for the core layer at 70°C or more as described above, the heat resistance required for the solar cell encapsulant can be imparted. In addition, in relation to the heating conditions during melt molding for sheeting into a sheet-like solar cell encapsulant and during the heat lamination process for integration into a solar cell module, the melting point of the encapsulant composition for the core layer may generally be about 110°C or less. The melting point of the encapsulant composition for the core layer is preferably 100°C or less from the viewpoint of sufficiently enhancing the molding properties of the sheet-like solar cell encapsulant.

The encapsulant composition for the skin layer may contain a silane-modified polyethylene resin. When a silane-modified polyethylene resin is added to the encapsulant composition for the skin layer, the silane-modified polyethylene resin may have a weight average molecular weight of 70,000 or more in terms of polystyrene and a melting point of about 90°C. In the sheet-shaped solar cell encapsulant, the silane-modified polyethylene resin preferably acts as an intermediate melting point resin component.

The density of the encapsulant composition for the skin layer is preferably 0.880 g/cm ³ or more and 0.910 g/cm ³ or less, and more preferably 0.880 g/cm ³ or more and 0.899 g/cm ³ or less.

The melting point of the encapsulant composition for the skin layer is preferably 70°C or more and 90°C or less, more preferably 70°C or more and 80°C or less. As long as the melting point of the skin layer can be kept within the above range, as with the core layer, polyethylene resins with different melting points can be appropriately mixed to form the encapsulant composition for the skin layer. As a preferred example of the blending material resin for the encapsulant composition for the core layer, for example, a resin composition in which three types of polyethylene resins with melting points of 60°C, 90°C, and 97°C are mixed in amounts of 65 parts by mass, 8 parts by mass, and 20 parts by mass, respectively, can be mentioned. This resin composition can make the melting point of the entire core layer 73°C. By making the melting point of the encapsulant composition for the skin layer 70°C or more, it is possible to impart the heat resistance required for the solar cell encapsulant. In addition, by making the melting point of the encapsulant composition for the skin layer 90°C or less, it is possible to maintain the molding characteristics of the encapsulant sheet during integration into a solar cell module within a preferred range.

The silane-modified polyethylene resin contained in each layer is preferably a high molecular weight type silane-modified polyethylene resin.

The thickness of the core layer in the sheet-shaped solar cell encapsulant is preferably 0.2 mm or more and 0.4 mm or less, more preferably 0.25 mm or more and 0.35 mm or less. The thickness of each layer of the skin is preferably 0.03 mm or more and 0.1 mm or less, more preferably 0.035 mm or more and 0.080 mm or less. The total thickness of the two layers of skin laminated on both sides of the core layer is preferably 1/20 to 1/3 of the total thickness of the sheet-shaped solar cell encapsulant, more preferably 1/15 to 1/4. By setting the thickness of each layer of the sheet-shaped solar cell encapsulant in such a range, the heat resistance and molding characteristics of the sheet-shaped solar cell encapsulant can be maintained in a good range.

The sheet-shaped solar cell encapsulant can be produced by a known sheet molding method using a T-die extruder, a calendar molding machine, or the like. The sheet-shaped solar cell encapsulant can be obtained, for example, by adding a crosslinking agent to an ethylene-α-olefin copolymer, and, if necessary, dry-blending additives such as a hindered amine-based light stabilizer, a crosslinking assistant, a silane coupling agent, an ultraviolet absorber, an antioxidant, and a light stabilizer, beforehand, feeding the mixture from a hopper of a T-die extruder, and extruding the mixture into a sheet at an extrusion temperature of 80 to 150°C. When dry-blending the mixture, some or all of the additives can be used in the form of a master batch. In addition, in the T-die extrusion and calendar molding, a polyethylene resin composition in which some or all of the additives are melt-mixed with an amorphous α-olefin copolymer beforehand can also be used. For the melt mixing, a single-screw extruder, a twin-screw extruder, a Banbury mixer, a kneader, or the like can be used. In addition, the molded sheet is wound up on a paper tube for easy storage and transportation, but at this time, the sheets may adhere to each other (blocking may occur). If blocking occurs, the sheet cannot be stably unwound when it is to be used in the next process, resulting in reduced productivity. For this reason, it is common to avoid blocking by roughening the sheet surface or creating an uneven structure.

When manufacturing a solar cell module, a sheet of the solar cell encapsulant is prepared in advance, and then pressed at a temperature at which the polyethylene resin composition of the solar cell encapsulant melts, for example, 150 to 200°C, to form a module with the above-described configuration.

On the other hand, when manufacturing a solar cell module, the solar cell encapsulant can be temporarily attached to the solar cell element and protective material at a temperature at which the organic peroxide does not substantially decompose and the solar cell encapsulant melts, and then the temperature can be raised to achieve sufficient adhesion and crosslinking of the ethylene-α-olefin copolymer. In this case, in order to obtain a solar cell module with good heat resistance, in which the melting point (DSC method) of the solar cell encapsulant is 85°C or higher and the storage modulus at 150°C is 103 Pa or higher, it is preferable to crosslink the solar cell encapsulant so that the gel fraction (1 g of sample is immersed in 100 ml of xylene, heated at 110°C for 24 hours, filtered through a 400 mesh wire screen, and the mass fraction of the unmelted portion is measured) is preferably 50 to 98%, more preferably 70 to 95%.

In the process of sealing solar cell elements, the solar cell elements are covered with the solar cell sealing material, and then temporarily bonded by heating for several minutes to about 10 minutes at a temperature at which the organic peroxide does not decompose, and then bonding by heating for 5 to 30 minutes in an oven at a high temperature of about 150 to 200°C at which the organic peroxide decomposes.

The present invention includes the following aspects.
[1] An ethylene-α-olefin copolymer satisfying all of the following requirements (i) to (iv):
(i) Vicat softening point is 85.0°C or less.
(ii) When the melt torque at 160°C is X [N m] and the melt flow rate is Y [g/10 min], the value of X + 6.5 × Ln(Y) is 23.0 or less.
(iii) When the differential molecular weight distribution curve is divided into three normal distribution curves, the ratio of the sum of the peak heights of the medium molecular weight distribution component (component B) and the high molecular weight component (component C) to the peak height of the low molecular weight component (component A) is 10.00 or more.
(iv) A melt flow rate of 0.10 g/10 min or more and 10.00 g/10 min or less.
[2] The ethylene-α-olefin copolymer according to the above [1], wherein the ethylene-α-olefin copolymer has a Vicat softening point of 80.0° C. or lower.
[3] The ethylene-α-olefin copolymer according to the above [1] or [2], wherein the ethylene-α-olefin copolymer has a value of X+6.5×Ln(Y) of 21.0 or less.
[4] The ethylene-α-olefin copolymer according to any one of the above [1] to [3], wherein, when a differential molecular weight distribution curve of the ethylene-α-olefin copolymer is divided into three normal distribution curves, the ratio of the sum of the peak heights of a medium molecular weight distribution component (component B) and a high molecular weight component (component C) to the peak height of a low molecular weight component (component A) is 11.00 or more.
[5] The ethylene-α-olefin copolymer according to any one of the above [1] to [4], wherein the ethylene-α-olefin copolymer has a melt flow rate of 0.20 g/10 min or more and 10.00 g/10 min or less.
[6] The ethylene-α-olefin copolymer according to any one of the above [1] to [5], wherein the α-olefin of the ethylene-α-olefin copolymer includes at least one selected from propylene, butene, and hexene.
[7] A method for producing an ethylene-α-olefin copolymer having a density of 911 kg/m3 or ^less by copolymerizing ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of an olefin polymerization catalyst, comprising:
A method for producing an ethylene-α-olefin copolymer, comprising adjusting polymerization conditions so that A defined in the following formula (1) is 67.0 or more and 100.0 or less.

[8] The concentration of gas other than hydrocarbons in the above formula (1) is the sum of the hydrogen concentration and the nitrogen concentration,
The method for producing an ethylene-α-olefin copolymer according to the above [7], wherein the nitrogen concentration is 5 mol % or more and 30 mol % or less.
[9] The method for producing an ethylene-α-olefin copolymer according to the above [7] or [8], wherein the polymerization temperature in the above formula (1) is 66° C. or higher and 84° C. or lower.
[10] The method for producing an ethylene-α-olefin copolymer according to any one of the above [7] to [9], wherein the olefin polymerization catalyst is a polymerization catalyst using, as catalyst components, a solid particulate co-catalyst component obtained by supporting at least one co-catalyst component selected from an organoaluminum compound, an organoaluminum oxy compound, a boron compound, and an organozinc compound on a particulate support, and a metallocene complex having a ligand having a structure in which two cyclopentadienyl-type anion skeletons are bonded via at least one bridging group selected from an alkylene group and a silylene group.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[Test Example 1]
The items in Examples 1-1 to 1-7 and Comparative Examples 1-1 to 1-5 were measured or evaluated by the following methods.

(1) Melt flow rate (MFR, unit: g/10 min)
The measurement was carried out according to Method A specified in JIS K7210-1995, under conditions of a temperature of 190° C. and a load of 2.16 kg.

(2) Density (unit: kg/m ³ )
After carrying out annealing as specified in JIS K6760-1995, the measurement was carried out by Method A according to the method specified in JIS K7112-1980.

(3) Differential molecular weight distribution curve (GPC)
The molecular weight of the sample was measured by the GPC method under the following conditions. Ortho-dichlorobenzene (0.1 w/V dibutylhydroxytoluene was added as an antioxidant) was used as the solvent, and the sample concentration was 1 mg/mL. The instrument used was HLC-8121GPC/HT manufactured by Tosoh Corporation. The measurement column was a Tosoh Corporation GPC column, TSKgel GMHHR-H(S)HT 7.5 mm, ID x 300 mm, three columns connected together. The mobile phase was ortho-dichlorobenzene (0.1 w/V dibutylhydroxytoluene was added as an antioxidant), the flow rate was 1 mL/min, the column oven temperature was 140 ° C, the autosampler temperature was 140 ° C, and the system oven temperature was 40 ° C. The detector used was a refractive index detector (RID), the RID cell temperature was 140 ° C, and the sample solution injection amount was 300 μL. The measured value was multiplied by the Q factor value of 41.3 to obtain the polystyrene equivalent molecular weight (M).

(4) Peak Division of Differential Molecular Weight Distribution Curve A specific method for dividing a differential molecular weight distribution curve using Python of the present invention is as follows.
The first step is to download and install the Anaconda version of the corresponding model and configure it.
In the second step, the title of the first column of the electronic data of the differential molecular weight distribution curve is changed to "x" and the title of the second column is changed to "y." Next, the logM value is entered after the second line in the first column, and dwt/d(logM) is entered after the second line in the second column, and then saved as a csv file ('data name.csv').
In the third step, the following code was entered and executed using Jupyter Notebook (Anaconda3).

#Loading modules
from scipy.optimize import curve_fit
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.cm as cm
import pandas as pd

# Enter data
dataset = pd.read_csv('data name.csv')
x = dataset['x']
y = dataset['y']

#Define the fitting function
def func(x, *params):

# Determine the number of functions to fit based on the length of params
num_func = int(len(params)/3)

# Insert each parameter into the Gaussian function and add it to y_list
y_list = []
for i in range(num_func):
y = np.zeros_like(x)
param_range = list(range(3*i,3*(i+1),1))
amp = params[int(param_range[0])]
ctr = params[int(param_range[1])]
wid = params[int(param_range[2])]
y = y + amp * np.exp( -((x - ctr)/wid)**2)
y_list.append(y)

# Overlay all the Gaussian functions in y_list
y_sum = np.zeros_like(x)
for i in y_list:
y_sum = y_sum + i

# Add background
y_sum = y_sum + params[-1]
return y_sum

# Define the Gaussian function used for fitting: y = amp*exp[-((x-ctr)/wid)^2]
# amp = 1/(sqrt(2pi)*sig), ctr = m, wid = 2sig
def fit_plot(x, *params):
num_func = int(len(params)/3)
y_list = []
for i in range(num_func):
y = np.zeros_like(x)
param_range = list(range(3*i,3*(i+1),1))
amp = params[int(param_range[0])]
ctr = params[int(param_range[1])]
wid = params[int(param_range[2])]
y = y + amp * np.exp( -((x - ctr)/wid)**2) + params[-1]
y_list.append(y)
return y_list

#Setting initial values
# guess.appen([amp,ctr,wid]) --> amp: height, ctr: center value, wid: width
#If any of the following apply, change the initial values of "Amp", "Center", and "Width" until the condition no longer applies.
#If you get a Runtime Error
#When any one or more of Amp, Center, and Width is a negative value
#If the absolute value of Baseline is greater than 3
guess = []
guess.append([initial value of "Amp", initial value of "Center", initial value of "Width"]) # 1st curve
guess.append([initial value of "Amp", initial value of "Center", initial value of "Width"]) # 2nd curve
guess.append([initial value of "Amp", initial value of "Center", initial value of "Width"]) # 3rd curve

# Initial background value
background = 0.1

# Combining initial value lists
guess_total = []
for i guess:
guess_total.extend(i)
guess_total.append(background)

# Fitting Assign optimized parameters to popt
popt, pcov = curve_fit(func, x, y, p0=guess_total)

# Plotting experimental and optimization data
fit = func(x, *popt)
plt.figure(figsize=(8,5))
plt.scatter(x, y, marker="o", s=50, c="blue")
plt.plot(x, fit , ls='-', c='red', lw=3)

# Plot each curve
y_list = fit_plot(x, *popt)
baseline = np.zeros_like(x) + popt[-1]
for n, i in enumerate(y_list):
plt.fill_between(x, i, baseline, facecolor=cm.rainbow(n/len(y_list)), alpha=0.7)

# List of parameters, Baseline is added to the whole
data = {
"C1" : popt[0:3],
"C2" : popt[3:6],
"C3" : popt[6:9],
"Baseline" : popt[9:10],
}

# Display parameters in list format
idx = ["Amp","Center","Width"]
df = pd.DataFrame(data, index=idx)
df

Peak height ratio (unit: none)
The three peak center values ("Center") obtained by the above method were designated as components A, B, and C in ascending order of value, and the ratio of the sum of the peak heights of components B and C to the peak height ("Amp") of component A was calculated.

(5) Vicat softening point (unit: °C)
The sample was pressed by a hot press to prepare a sheet having a thickness of about 5 mm, and the obtained sheet was measured according to the A50 method specified in JIS K7206-1999.

(6) Melting torque (unit: N m)
Measurements were performed under the following conditions using a Labo Plastomill. The equipment used was a Labo Plastomill 3S150 manufactured by Toyo Seiki Co., Ltd. 38 g of sample was mixed with 400 ppm of Sumilizer GP, an antioxidant manufactured by Sumitomo Chemical Co., Ltd., and kneaded for 30 minutes at a set temperature of 160°C and a screw rotation speed of 60 rpm. Melt torque data during kneading was obtained at 0.125 second intervals, and the average value was calculated for 5 minutes from 25 minutes after the start of kneading to the end of measurement.

(7) Filler acceptance (unit: %)
A sample was prepared under the following conditions using a Labo Plastomill. The equipment used was a Labo Plastomill 3S150 manufactured by Toyo Seiki Co., Ltd. 150 parts of magnesium hydroxide Kisuma 5B manufactured by Kyowa Chemical Industry Co., Ltd. was mixed with 40 g of sample, and kneaded for 10 minutes under the conditions of a set temperature of 150 ° C. and a screw rotation speed of 50 rpm. The kneaded product obtained was left to stand at 150 ° C. for 5 minutes (preheating step), pressurized at 150 ° C. and 5 MPa for 5 minutes (pressing step), and slowly cooled at 30 ° C. for 5 minutes (slow cooling step) to obtain a pressed sheet with a thickness of 1 mm. The obtained sheet was cut into a shape of JIS-K7127 Type 5. The cut sheet was set in a Tensilon universal testing machine RTG-1225-PL manufactured by Orientec Co., Ltd., and a tensile test was performed at a tensile speed of 200 mm / min in accordance with JIS-K7127 using a 200 N load cell. The gauge length elongation at break was taken as the filler acceptance.

(8) Appearance of extrusion molded product Using a Toyo Seiki Capillograph, melt extrusion was performed at a barrel setting temperature of 190°C, L = 40 mm/D = 1 mm, a tungsten carbide orifice with an inlet angle of 90°, and a piston descending speed of 100 mm/min, and the extruded strand was recovered. The surface of the strand was visually observed, and those with good appearance were rated as ◯, and those with poor appearance were rated as ×.

[Production Example of Component (H)]
[Example 1-1]
(1) Production of Component (H) Component (H) was produced in the same manner as in the preparation of Component (A) in Examples 1 (1) and (2) described in JP 2009-79180 A. As a result of elemental analysis, Zn was 11 mass % and F was 6.4 mass %.
(2) Production of Prepolymerization Catalyst Component 41 liters of butane was added to a 210 liter autoclave equipped with a stirrer, which had been previously replaced with nitrogen, and then 60.9 mmol of racemic ethylene bis(1-indenyl)zirconium diphenoxide was added. The autoclave was heated to 50°C and stirred for 2 hours. Next, 0.60 kg of the component (H) obtained above was added to the autoclave. Thereafter, the temperature of the autoclave was lowered to 31°C, and after the inside of the system was stabilized, 0.1 kg of ethylene and 0.1 liter of hydrogen (normal temperature and normal pressure) were added to the autoclave, followed by the addition of 240 mmol of triisobutylaluminum to initiate prepolymerization. Ethylene and hydrogen (normal temperature and normal pressure) were supplied to the autoclave at 0.5 kg/hr and 1.1 liter/hr, respectively, for 30 minutes, and then the temperature was raised to 50°C, and ethylene and hydrogen (normal temperature and normal pressure) were supplied to the autoclave at 2.7 kg/hr and 8.2 liter/hr, respectively. The prepolymerization was carried out for a total of 10.0 hours. After the completion of the prepolymerization, ethylene, butane, hydrogen, etc. were purged, and the remaining solid was vacuum-dried at room temperature to obtain a prepolymerization catalyst component containing 4.14 g of polyethylene per 1 g of component (H). The [η] of the polyethylene was 1.26 dl/g.
(3) Production of component (A) (LLDPE1) In the presence of the prepolymerized catalyst component obtained in (2) above, copolymerization of ethylene and 1-hexene was carried out in a continuous fluidized bed gas phase polymerization apparatus to obtain a powder of an ethylene-1-hexene copolymer (hereinafter referred to as LLDPE1). The polymerization conditions were as follows: polymerization temperature: 72°C; polymerization pressure: 2.0 MPa; molar ratio of hydrogen to ethylene: 0.49%; molar ratio of 1-hexene to the total of ethylene and 1-hexene: 2.2%. Ethylene, 1-hexene and hydrogen were continuously supplied during polymerization to maintain a constant gas composition.

The above prepolymerization catalyst components, triisobutylaluminum, and triethylamine were continuously fed to maintain a constant total powder mass of 80 kg in the fluidized bed. The amount of triisobutylaluminum relative to LLDPE1 was 0.43 mmol/kg. The molar ratio of triethylamine to triisobutylaluminum was 3%. The average polymerization time was 5.0 hours. The obtained LLDPE1 powder was granulated using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) under conditions of a feed rate of 50 kg/hr, a screw rotation speed of 338 rpm, a gate opening of 50%, a suction pressure of 0.1 to 0.2 MPa, and a resin temperature of 180 to 200°C, to obtain pellets of LLDPE1. The physical properties of the obtained LLDPE1 pellets were evaluated, and the results are shown in Table 2.

[Examples 1-2 to 1-7]
Except for changing the conditions shown in Table 1, the same conditions as in Example 1-1 were used to obtain pellets of LLDPE2 to 7, respectively.

[Comparative Example 1-1]
Except for changing the conditions shown in Table 1, the same conditions as in Example 1-1 were used to obtain pellets of LLDPE8.

[Comparative Example 1-2]
Pellets of LLDPE9 (MFR=0.28 g/10 min, density=913 kg/m ³ ) manufactured by Sumitomo Chemical Co., Ltd. were used.

[Comparative Example 1-3]
Pellets of LLDPE10 (MFR=1.97 g/10 min, density=913 kg/m ³ ) manufactured by Sumitomo Chemical Co., Ltd. were used.

[Comparative Examples 1 to 4]
Pellets of LLDPE11 (MFR=1.25 g/10 min, density=904 kg/m ³ ) manufactured by Sumitomo Chemical Co., Ltd. were used.

[Comparative Examples 1 to 5]
Pellets of LDPE1 (MFR=0.34 g/10 min, density=922 kg/m ³ ) manufactured by Sumitomo Chemical Co., Ltd. were used.

As can be seen from Table 2, Examples 1-1 to 1-7, which satisfy all of the constituent requirements of the present invention, exhibited greater filler acceptance than Comparative Examples 1-1 to 1-5, and also performed well in the extrusion processability evaluation. Therefore, it was demonstrated that the ethylene-α-olefin copolymer of the present invention has relatively excellent acceptance of the filler contained as a flame retardant while maintaining appropriate extrusion processability.

[Test Example 2]
The items in Examples 2-1 to 2-8 and Comparative Examples 2-1 to 2-6 were measured or evaluated by the following methods.

(1) Melt flow rate (MFR, unit: g/10 min)
The measurement was carried out according to Method A specified in JIS K7210-1995, under conditions of a temperature of 190° C. and a load of 2.16 kg.

(2) Vicat softening point (unit: °C)
The sample was pressed by a hot press to prepare a sheet having a thickness of about 5 mm, and the obtained sheet was measured according to the A50 method specified in JIS K7206-1999.

(3) Density (unit: kg/m ³ )
The measurement was performed according to the method specified in JIS K7112-1980.

(4) Number of short chain branches (unit: 1/1000C)
< ^13C -NMR measurement of standard product>
Carbon nuclear magnetic resonance ( ¹³ C-NMR) spectrum of the standard was measured under the following measurement conditions: FS140A manufactured by Sumitomo Chemical Co., Ltd. was used as the standard.
(Measurement condition)
Apparatus: AVANCE600 manufactured by Bruker
Measurement probe: 10 mm cryoprobe Measurement solvent: 1,2-dichlorobenzene-d4
Measurement temperature: 135°C
Measurement method: Proton decoupling method Pulse width: 45 degrees Pulse repetition time: 4 seconds Window function: negative exponential function and Gaussian function Number of accumulations: 5000

<Number of short chain branches of standard product>
The obtained carbon nuclear magnetic resonance ( ¹³ C-NMR) spectrum was analyzed using an exponential function, and the amount of short chain branches was calculated as the peak area derived from a methine carbon bonded with a branch having two carbon atoms when the sum of the peak areas of all peaks having peak tops at 5 to 50 ppm was set to 1000. Under these measurement conditions, the amount of short chain branches was calculated from the peak areas of the peaks at 10.9 to 11.4 ppm.

<Infrared spectroscopy measurement>
For example, as described in "New Polymer Analysis Handbook, First Edition, p. 590, edited by the Japan Analytical Chemistry Association," it is known that short chain branches of ethylene-α-olefin copolymers are observed to have a peak at 1378 cm ^-1 in infrared spectroscopy. The ethylene-α-olefin copolymer was heated at 6 MPa for 5 minutes using a heat press preheated at 150° C. for 5 minutes, and then cooled in a water-cooled mold for 5 minutes to be molded to a thickness of 0.01 cm. The thickness after molding was measured with a thickness gauge. The infrared spectroscopy spectrum of the molded ethylene-α-olefin copolymer was measured under the following measurement conditions. The infrared spectroscopy spectrum of the standard sample for which 13C-NMR was measured was also measured using the same procedure.

(Measurement condition)
Apparatus: FTIR470plus manufactured by JASCO Corporation
Detector: TGS
Number of scans: 16 Resolution: 2 cm ^-1
Vertical axis: absorbance

<Number of short chain branches>
In the obtained infrared spectrum, a straight line was drawn connecting 955 cm ⁻¹ and 1790 cm ⁻¹ to obtain a baseline. The number of short chain branches B was calculated by the formula (i).
B = Bs × F / Fs Formula (i)
Here, Bs is the number of short chain branches determined by 13C-NMR of a standard product, F is given by formula (ii), and Fs is given by formula (iii).
F = (A1 / (ρ × t) - 0.95A2 / (ρ × t) + 3.8) Formula (ii)
Fs = (A1s / (ρs × ts) - 0.95A2 / (ρs × ts) + 3.8) Formula (iii)
Here, A1 is the height from the baseline at 1378 cm ^-1 in the infrared spectrum of the ethylene-α-olefin copolymer, ρ is the density of the ethylene-α-olefin copolymer (g/cm ³ ), t is the measured thickness of the ethylene-α-olefin copolymer (cm), A2 is the maximum height in the range of 1281 to 1324 cm ^-1 in the infrared spectrum of the ethylene-α-olefin copolymer after baseline subtraction, A1s is the height from the baseline at 1378 cm ^-1 in the infrared spectrum of the standard, ρs is the density of the standard (g/cm ³ ), ts is the measured thickness of the standard, and A2s is the maximum height in the range of 1281 to 1324 cm ^-1 in the infrared spectrum of the standard after baseline subtraction.

(5) Lump ratio (unit: wtppm)
The polymer powder discharged from the gas phase polymerization apparatus was passed through a sieve with a mesh size of 10 mm, and the mass ratio of the amount of polymer remaining on the sieve to the amount of polymer passing through the sieve was calculated. Note that, for Comparative Example 2-2, the lump ratio could not be calculated because of the difficulty in operation.

(6) Dispersal rate (unit: wtppm)
The polymer particles scattered from the top of the gas phase polymerization apparatus together with the gas circulating in the apparatus were recovered using a solid-gas separator, and the mass ratio of the amount of the recovered particles to the amount of the polymer passing through the sieve in (5) above was calculated as the scattering rate. Note that, for Comparative Example 2-2, the operation was difficult, so the scattering rate could not be determined.

(7) Driving Evaluation Driving evaluation was performed based on the following indicators.
◯: The lump rate and scattering rate were relatively low, and stable operation was possible.
Level indication fluctuation: The level indication of the fluidized bed in the tank, measured using a differential pressure gauge, became unstable, making it difficult to continue operation.
Lump increase: The lump rate has increased.
Excessive scattering: The scattering rate was excessive.

[Example 2-1]
In the presence of the prepolymerized catalyst component obtained in (2) of [Example 1-1] above, copolymerization of ethylene and 1-hexene was carried out in a continuous fluidized bed gas phase polymerization apparatus to obtain a powder of LLDPE12. The polymerization conditions were as follows: polymerization temperature 84°C; polymerization pressure 2.0 MPaG; ethylene concentration in the gas phase 87.3 mol%; hydrogen concentration 0.8 mol%; hexene concentration 2.1 mol%; hexane concentration 0.3 mol%; nitrogen concentration 9.5 mol%. The prepolymerized catalyst component, triisobutylaluminum, and triethylamine were continuously fed, and the total powder mass of the fluidized bed was kept constant at 80 kg. The amount of triisobutylaluminum relative to LLDPE12 (X/PE) was 0.37 mmol/kg. The molar ratio of triethylamine to triisobutylaluminum (Z/X) was 3%. The average residence time was 3.9 hr. The resulting LLDPE12 powder had a density of 904 kg/m ³ , a short chain branch number of 27.4, a lump ratio of 92 wtppm, and a scattering ratio of 118 wtppm.

[Examples 2-2 to 2-8]
Pellets of LLDPE13 to 19 were obtained under the same conditions as in Example 2-1, except that the polymerization conditions shown in Table 3 were changed. The amount of triisobutylaluminum relative to LLDPE (X/PE), the molar ratio of triethylamine to triisobutylaluminum (Z/X), the average residence time, the density, number of short chain branches, lump ratio, and scattering ratio of the obtained LLDPE powder are shown in Table 3.

[Comparative Examples 2-1 to 2-6]
Except for changing the polymerization conditions shown in Table 3, the same conditions as in Example 2-1 were used to obtain pellets of LLDPE 20 to 25. The amount of triisobutylaluminum relative to LLDPE (X/PE), the molar ratio of triethylamine to triisobutylaluminum (Z/X), the average residence time, the density of the obtained LLDPE powder, the number of short chain branches, the lump ratio, and the scattering ratio are shown in Table 3.

As can be seen from the results in Table 3, Examples 2-1 to 2-8, which satisfy all of the constituent requirements of the present invention, had relatively low lump ratios and scattering rates and were relatively unlikely to experience poor flow, allowing for stable operation.

The ethylene-α-olefin copolymer of the present invention can increase the acceptability of fillers while maintaining suitable extrusion processability. Therefore, the ethylene-α-olefin copolymer of the present invention can be used in various industrial fields such as sheets, containers, insulators such as electric wires and cables, sheaths, solar cell encapsulants, etc.

Claims (10)

An ethylene-α-olefin copolymer which satisfies all of the following requirements (i) to (iv):
(i) Vicat softening point is 85.0°C or less.
(ii) When the melt torque at 160°C is X [N m] and the melt flow rate is Y [g/10 min], the value of X + 6.5 × Ln(Y) is 23.0 or less.
(iii) When the differential molecular weight distribution curve is divided into three normal distribution curves, the ratio of the sum of the peak heights of the medium molecular weight distribution component (component B) and the high molecular weight component (component C) to the peak height of the low molecular weight component (component A) is 10.00 or more.
(iv) A melt flow rate of 0.10 g/10 min or more and 10.00 g/10 min or less. The ethylene-α-olefin copolymer according to claim 1, wherein the ethylene-α-olefin copolymer has a Vicat softening point of 80.0°C or less. The ethylene-α-olefin copolymer according to claim 1 or 2, wherein the value of X+6.5×Ln(Y) of the ethylene-α-olefin copolymer is 21.0 or less. The ethylene-α-olefin copolymer according to claim 1 or 2, in which the ratio of the sum of the peak heights of the medium molecular weight distribution component (component B) and the high molecular weight component (component C) to the peak height of the low molecular weight component (component A) when the differential molecular weight distribution curve of the ethylene-α-olefin copolymer is divided into three normal distribution curves is 11.00 or more. The ethylene-α-olefin copolymer according to claim 1 or 2, wherein the melt flow rate of the ethylene-α-olefin copolymer is 0.20 g/10 min or more and 10.00 g/10 min or less. The ethylene-α-olefin copolymer according to claim 1 or 2, wherein the α-olefin of the ethylene-α-olefin copolymer includes at least one selected from propylene, butene, and hexene. A method for producing an ethylene-α-olefin copolymer having a density of 911 kg/m3 or less by copolymerizing ethylene and an α-olefin having 3 to ²⁰ carbon atoms in the presence of an olefin polymerization catalyst, comprising the steps of:
A method for producing an ethylene-α-olefin copolymer, comprising adjusting polymerization conditions so that A defined in the following formula (1) is 67.0 or more and 100.0 or less.
The concentration of gas other than hydrocarbons in the above formula (1) is the sum of the hydrogen concentration and the nitrogen concentration,
The method for producing an ethylene-α-olefin copolymer according to claim 7, wherein the nitrogen concentration is 5.0 mol % or more and 30.0 mol % or less. The method for producing an ethylene-α-olefin copolymer according to claim 7 or 8, wherein the polymerization temperature in the above formula (1) is 66°C or higher and 84°C or lower. The method for producing an ethylene-α-olefin copolymer according to claim 7 or 8, wherein the olefin polymerization catalyst is a polymerization catalyst using, as catalyst components, a solid particulate cocatalyst component in which at least one cocatalyst component selected from an organoaluminum compound, an organoaluminum oxy compound, a boron compound, and an organozinc compound is supported on a particulate carrier, and a metallocene complex having a ligand having a structure in which two cyclopentadienyl-type anion skeletons are bonded by at least one bridging group selected from an alkylene group and a silylene group.