WO2012018140A1

WO2012018140A1 - Method for measuring crosslinking density of molded article of crosslinked thermoplastic polymer foam and molded article of crosslinked foam

Info

Publication number: WO2012018140A1
Application number: PCT/JP2011/068210
Authority: WO
Inventors: 勝大山田; 博豊田
Original assignee: 住友化学株式会社
Priority date: 2010-08-06
Filing date: 2011-08-03
Publication date: 2012-02-09
Also published as: CN103068893A; JP2012052106A; CN103068893B

Abstract

The present invention relates to a molded article of a crosslinked ethylenic polymer foam. The molded article of a crosslinked ethylenic polymer foam has a crosslinking density of 0.30 mol/kg or higher as determined using a relaxation modulus based on a stress relaxation measurement obtained by measuring the stress relaxation of the molded article of the crosslinked foam when the molded article of the crosslinked foam is subjected to compressive deformation under conditions of a measurement temperature of 60ºC, compressive strain of 50%, and a measurement time of 1,800 seconds. The present invention also relates to a method for measuring the crosslinking density of a molded article of a crosslinked thermoplastic polymer foam, the method comprising: a step for heating the molded article of the crosslinked thermoplastic polymer foam to a predetermined temperature; a step for applying pressure to the molded article of the crosslinked thermoplastic polymer foam, which is maintained at the predetermined temperature, in order to induce compressive deformation of the molded article of the crosslinked foam, and for measuring the stress relaxation of the molded article of the crosslinked foam while the compressive strain of the molded article of the crosslinked foam is maintained at a constant level; a step for determining a relaxation modulus (Gc) from the stress relaxation; and a step for calculating the crosslinking density of the crosslinked thermoplastic polymer foam from Gc using the following formula in which Gc is the elastic modulus when the stress of the molded article of the crosslinked foam is at a constant level: n = Gc/RT (n: crosslinking density, R: gas constant, T: measurement temperature).

Description

Method for measuring crosslink density of crosslinked foam molded article made of thermoplastic polymer, and crosslinked foam molded article

The present invention relates to a method for measuring the crosslinking density of a thermoplastic polymer crosslinked foamed molded article, and a crosslinked foamed molded article having a crosslinking density calculated by the measuring method of a certain value or more.

Crosslinked foamed molded articles made of thermoplastic polymers are widely used for daily goods, flooring materials, sound insulation materials, heat insulating materials and the like. Among them, a cross-linked foamed molded article made of an ethylene polymer is used for footwear members (outer sole (lower bottom), midsole (upper bottom), insole (sole), etc.)). Examples of the crosslinked foamed molded product made of an ethylene polymer include a crosslinked foamed molded product obtained by crosslinking and foaming an ethylene-vinyl acetate copolymer as described in JP-B-3-2657, and JP-A-2005-314638. There is known a cross-linked foamed molded product obtained by cross-linking and foaming an ethylene-α-olefin copolymer as described in Japanese Patent Publication No. JP-A.
By the way, crosslinking density is known as one of the elements that greatly affect various physical properties of the crosslinked foamed molded article. The crosslinking density is also referred to as an effective network chain concentration, and represents the number of cross-linking points between the polymers constituting the crosslinked foamed molded product contained in the unit weight of the foamed molded product. As a method for measuring the cross-linking density of a vulcanized rubber cross-linked foamed molded article, for example, a method described in JP-A-2007-238783 is known. In this method, two or more solid bodies, that is, non-foamed molded bodies, which are the same type of polymer as the foamed molded body whose crosslink density is to be measured and have different crosslinking densities, are used. The crosslink density of each solid body is calculated in advance by using equilibrium swelling, and the relaxation times of the solid bodies for which the crosslink density has been calculated are measured by a pulse nuclear magnetic resonance (NMR) apparatus. From the above, a calibration curve of the same kind of polymer is prepared. Next, the relaxation time in the foam molded article is measured by the pulse nuclear magnetic resonance (NMR) apparatus, and the crosslinking density of the foam molded article is calculated based on the calibration curve.
However, it has been difficult to measure the crosslink density of a crosslinked foamed product made of an ethylene polymer by the method described in JP-A-2007-238783. This is presumed that the measurement method does not provide sufficient accuracy because the crosslink density of the cross-linked foamed product made of an ethylene polymer is much lower than that of the cross-linked foamed product made of vulcanized rubber. .
Further, as a method for easily knowing the amount of effective network chain structure of a crosslinked foamed molded product, a method for measuring a gel fraction is known. This utilizes the property that the effective network chain structure is generally insoluble in any solvent. By infiltrating the crosslinked foamed product into an organic solvent and heating it under certain conditions, components soluble in the solvent are extracted. The amount of the portion having the remaining effective network chain structure is determined. However, in this method, although the rough amount of the portion having an effective network chain structure can be determined, since it is selected only by its size, there is a problem that a small effective network chain structure is not recognized as an effective network chain structure. There has been a need for a more accurate method of measuring density.

FIG. 1 is a diagram showing a correlation between compression set and gel fraction of a crosslinked foamed molded article.
FIG. 2 is a diagram showing the correlation between the compression set of the crosslinked foamed molded article and the crosslinking density measured by the method of the present invention.

As a result of diligent studies to overcome the above-mentioned problems, the present inventor used a stress relaxation behavior obtained by compressively deforming a cross-linked foam molded article to be measured, thereby forming a cross-linked foam molded article made of a thermoplastic polymer. A method for accurately measuring the crosslink density of was found. In addition, the present inventors have found that a crosslinked foamed molded article having a crosslinking density calculated by the above measurement method exceeding a certain value is suitable as a member for shoes.
That is, the first of the present invention is a cross-linked foamed molded product made of an ethylene polymer, which is subjected to compression deformation under the conditions of a measurement temperature of 60 ° C., a compression strain of 50%, and a measurement time of 1800 seconds. The stress relaxation of the crosslinked foamed molded article is measured, and the crosslinked density determined using the relaxation elastic modulus obtained from the stress relaxation measurement is 0.30 mol / kg or more, and the crosslinked foamed molded article made of an ethylene polymer is used. Is.
The second of the present invention is a member for shoes comprising the above-mentioned crosslinked foamed molded article.
The third aspect of the present invention is a method for measuring the crosslinking density of a thermoplastic polymer crosslinked foamed molded article,
Heating the thermoplastic polymer cross-linked foam to a predetermined temperature;
A pressure is applied to the crosslinked foamed molded product made of a thermoplastic polymer maintained at a predetermined temperature to compressively deform the crosslinked foamed molded product, and while maintaining the amount of compressive strain of the crosslinked foamed molded product to be constant, Measuring stress relaxation;
A step of obtaining relaxation elastic modulus Gc from stress relaxation, where Gc is the elastic modulus when the stress of the crosslinked foamed molded article becomes constant,
Calculating the crosslinking density of the crosslinked foamed thermoplastic polymer from the Gc by the following formula.
n = Gc / RT
n: Crosslink density R: Gas constant T: Measurement temperature

Method of measuring crosslinking density of the crosslinked foamed molded article of the present invention is a method of calculating from the relaxation modulus of the crosslinked foamed molded article when obtained by compression deformation of the cross-linked foamed molded article. Specifically, it has a compressible mechanism such as a tensile tester with a compression function and a rotary viscometer with a compression function, and the stress at the time of compression of a cross-linked foamed molded article using an apparatus that can obtain stress data. Measure relaxation.
For example, an apparatus equipped with a stress sensor that can measure compressive stress, a parallel plate-shaped jig that sandwiches the sample, an oven that heats the sample, and a position sensor that can measure the amount of compressive strain is used. When measuring by heating a crosslinked foamed molded article, it is preferable to use a rotary viscometer having a compression function because the temperature can be easily controlled.
The shape of the sample is preferably a plate shape having parallel planes that can uniformly contact the jig surface.
The thickness of the sample in the range that can be sandwiched in the jig, can be freely set, and preferably 0.1 mm ~ 50 mm, more preferably 1 mm ~ 20 mm.
The shape of the sample on the surface in contact with the jig is preferably a point-symmetric shape such as a circle, square, or equilateral triangle. The area of the sample on the surface in contact with the jig is preferably equal to or slightly larger than the area of the jig.
The sample is sandwiched between the jig so that the center of the surface where the sample contacts the jig and the center of the jig coincide. A sample sandwiched between jigs is placed in an oven, and the sample is heated to the measurement temperature.
The measurement temperature can be freely set as long as the shape of the sample can be maintained. The measurement temperature is preferably a temperature at which 1% to 100% compressive strain can be applied to the sample. For samples of polymer melting or shape a glass transition point above which constitutes the sample can be maintained, it is preferable to carry out the measurements at the melting point or glass transition point above the temperature of the polymer.
Next, the sample is compressed by pressing the upper jig against the sample while maintaining the temperature of the sample. The amount of compressive strain applied to the sample is determined by the material, shape, and measurement temperature of the sample. The amount of compressive strain is defined by the following equation. The amount of compressive strain applied to the sample may be a non-linear region, that is, a region where the viscosity of the sample changes according to the amount of compressive strain when the amount of compressive strain applied to the sample is changed. The amount of compressive strain applied to the sample is preferably 1% to 100%, more preferably 10 to 100%.

The stress relaxation of the sample is measured while keeping the amount of compressive strain applied to the sample constant. The measurement time may be a time until the stress of the crosslinked foamed molded article disappears and the stress of the crosslinked foamed molded article becomes substantially constant, or a longer time.
The calculation method of the crosslinking density used in the present invention is as follows.
The relaxation elastic modulus Gc when the stress of the crosslinked foamed molded product is attenuated and the stress of the crosslinked foamed molded product becomes substantially constant is obtained, and the crosslinking density n of the crosslinked foamed molded product is calculated using the following formula.
n = Gc / RT
n: Crosslink density
R: Gas constant
T: Measurement temperature
The measuring method of the present invention can also be applied to a crosslinked foamed product made of an ethylene polymer, which has conventionally been difficult to accurately measure the crosslinking density. Especially, as the method of measuring crosslinking density of the crosslinked foamed molded body formed by using a high-pressure low-density polyethylene and / or ethylene -α- olefin copolymer, it is preferred.
Crosslinked foamed molded article which is capable of measuring the cross-linking density in the method of the present invention may be a cross-linked foamed molded article crosslinked in any way. Examples of the crosslinking method include electron beam crosslinking and a method of crosslinking a polymer with an organic peroxide. The measurement method of the present invention is suitable for the measurement of the crosslinking density of a crosslinked foamed molded product obtained by crosslinking a polymer with an organic peroxide.
Crosslinked foamed molded article of the present invention is mainly composed of ethylene-based polymer, the crosslinking density is 0.30 mol / kg or more cross-linked foamed molded article. The crosslinking density of the crosslinked foamed molded product is the compression modulus of the crosslinked foamed molded product obtained under the conditions of a measurement temperature of 60 ° C., a compression strain of 50%, and a measurement time of 1800 seconds. This is a calculated value. The crosslink density is preferably 0.30 mol / kg or more.
The ethylene polymer in the present invention is an ethylene-α-olefin copolymer, a high-pressure method low-density polyethylene, or a mixture thereof.
The ethylene-α-olefin copolymer is a copolymer containing a monomer unit based on ethylene and a monomer unit based on an α-olefin. 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 an α-olefin having 3 to 20 carbon atoms, more preferably an α-olefin having 4 to 8 carbon atoms, and still more preferably 1-butene or 1-hexene. , 1-octene and 4-methyl-1-pentene.
Examples of the ethylene-α-olefin copolymer include an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, an ethylene-4-methyl-1-pentene copolymer, and an ethylene-1-octene copolymer. Examples thereof include a polymer, an ethylene-1-butene-1-hexene copolymer, an ethylene-1-butene-4-methyl-1-pentene copolymer, and an ethylene-1-butene-1-octene copolymer. From the viewpoint of increasing the strength of the crosslinked foamed molded article, a copolymer having a monomer unit based on ethylene and a monomer unit based on an α-olefin having 6 to 8 carbon atoms, specifically, Ethylene-1-hexene copolymer, ethylene-1-octene copolymer, ethylene-1-butene-1-hexene copolymer, and ethylene-1-butene-1-octene copolymer.
In the ethylene-α-olefin copolymer, the content of monomer units based on ethylene is usually 80 to 98% by weight when the total weight of the ethylene-α-olefin copolymer is 100% by weight. , the content of the monomer unit based on α- olefins, when the total weight of the ethylene-based polymer is 100% by weight, usually 2-20% by weight.
The density of the ethylene polymer is usually 860 to 945 kg / m. ³ It is. The density is preferably 865 kg / m from the viewpoint of increasing the rigidity of the crosslinked foamed molded article. ³ Or more, more preferably 870 kg / m ³ Or more, more preferably 900 kg / m ³ That's it. Further, from the viewpoint of increasing the lightness of the crosslinked foamed molded article, preferably 940 kg / m. ³ It is as follows. It said seal degree, after annealed according to JIS K6760-1995, measured in accordance with the prescribed in JIS K7112-1980 underwater substitution method.
The melt flow rate (MFR; unit is g / 10 minutes) of the ethylene polymer is 0.01 to 3.0 g / 10 minutes. An MFR is preferably 0.01 g / 10 min or more because a foamed molded article having a high foaming ratio is obtained and foam moldability is also improved. Further, since the cross-linked foamed molded article having excellent strength can be obtained, MFR is preferably not more than 3.0 g / 10 min, more preferably not more than 2.5 g / 10 min. The MFR is measured by the A method according to JIS K7210-1995 under conditions of a temperature of 190 ° C. and a load of 21.18N. In the measurement of the melt flow rate, usually, an ethylene polymer previously blended with about 1000 ppm of an antioxidant is used.
The ethylene-based copolymer used in the present invention preferably has a flow activation energy (Ea) of 40 kJ / mol or more from the viewpoint of making the cell properties uniform in the crosslinked foamed molded article and improving the appearance. . Ea is preferably 50 kJ / mol or more, more preferably 55 kJ / mol or more. Furthermore, the Ea, from the viewpoint of the surface of the cross-linked foamed molded article smoother, preferably not more than 100 kJ / mol, more preferably not more than 90 kJ / mol.
The flow activation energy (Ea) is a master curve showing the dependence of the melt complex viscosity (unit: Pa · sec) at 190 ° C. on the angular frequency (unit: rad / sec) based on the temperature-time superposition principle. The shift factor (a _T ) And a numerical value calculated by the Arrhenius equation and obtained by the following method. 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 melt complex viscosity is Pa · sec. 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), Shift factor (a) at each temperature (T) obtained when superimposed on the melt complex viscosity-angular frequency curve of the coalesced _T ) Is obtained, and each of the temperature (T), from a shift factor (aT) at each temperature (T), by the method of least squares [ln (a _T )] And [1 / (T + 273.16)] are calculated. Next, Ea is obtained from the slope m of the linear expression and the following expression (II).
ln (a _T ) = M (1 / (T + 273.16)) + n (I)
Ea = | 0.008314 × m | (II)
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 (where the Y axis is the melt complex viscosity, the X axis Is the amount of movement when superposed on the melt complex viscosity-angular frequency curve at 190 ° C., and in the superposition, both the melt complex viscosity and the angular frequency at each temperature (T) are obtained. The logarithmic curve has an angular frequency a for each curve. _T Double the melt complex viscosity to 1 / a _T Move twice. Moreover, the correlation coefficient when determining 130 ° C., 0.99 ° C., from the values of four points 170 ° C. and 190 ° C. The formula (I) in the minimum square method is usually 0.99 or more.
The melt complex viscosity-angular frequency curve is measured using a viscoelasticity measuring apparatus (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 molecular weight distribution (Mw / Mn) of the ethylene-based polymer is preferably 3 or more, more preferably 5 or more, from the viewpoint of improving the moldability. Moreover, from a viewpoint of raising impact strength, Preferably it is 25 or less, More preferably, it is 20 or less, More preferably, it is 15 or less. The molecular weight distribution (Mw / Mn) is a value (Mw / Mn) obtained by dividing the weight average molecular weight (Mw) by the number average molecular weight (Mn). Mw and Mn are gel permeation chromatograph (GPC). ) Method. Moreover, as measurement conditions of GPC method, the following conditions can be mention | raise | lifted, for example.
(1) Apparatus: 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
It is generally known that a cross-linking reaction between molecular chains proceeds preferentially from a component having a high molecular weight. Therefore, in order to obtain a high crosslink density cross-linked foamed molded article, it is preferred to produce a cross-linked foamed molded article using the ethylene polymer containing a large amount of high molecular weight components. The ethylene polymer preferably has an HMw-Index (High Molecular Index) calculated by the GPC method of more than 8.0%. HMw-Index can be calculated according to the following formula from the profile of weight average molecular chain length (Aw) obtained from the GPC method.
HMw-Index (%)
= (Component ratio of LogAw> 4.5 or more) / (Component ratio of LogAw> 4.0 or more) × 100
More HMw-Index is high, can mean that higher proportions of the molecular chain component weight with high molecular weight, achieve a high crosslinking density crosslinked foamed molded article.
Examples of the method for producing an ethylene-α-olefin copolymer used for obtaining a crosslinked foamed product made of an ethylene polymer of the present invention having a crosslinking density of 0.30 mol / kg or more include an alkylene group and a silylene group. A metallocene complex having a ligand in which two (substituted) indenyl groups are bonded to each other by a bridging group, for example, a metallocene catalyst using ethylenebis (1-indenyl) zirconium diphenoxide as a catalyst component, and ethylene and α-olefin And a method of copolymerizing with.
In the metallocene-based catalyst, a promoter component that activates the metallocene complex is used. Examples of the promoter component include organic aluminum oxy compounds, boron compounds, and organic zinc compounds. These promoter components are preferably used by being supported on a particulate carrier.
As the particulate carrier, a porous material is preferable, and SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO ₂ Inorganic oxides such as; clays and clay minerals such as smectite, montmorillonite, hectorite, laponite, saponite; organic polymers such as polyethylene, polypropylene, styrene-divinylbenzene copolymer, etc. are used. The 50% volume average particle diameter of the particulate carrier is usually 10 to 500 μm, and the 50% volume average particle diameter is measured by a light scattering laser diffraction method or the like. The fine particle carrier has a pore volume of usually 0.3 to 10 ml / g, and the pore volume is mainly measured by a gas adsorption method (BET method). The specific surface area of the particulate carrier is usually 10 to 1000 m. ² / G, and the specific surface area is mainly measured by a gas adsorption method (BET method).
When the crosslinked foamed molded article of the present invention is used as a shoe member, a crosslinked foamed molded article excellent in compression set performance is desirable. As the method for producing an ethylene-α-olefin copolymer used for obtaining a crosslinked foamed article having excellent compression set, particularly preferably, the following promoter support (A) and an alkylene group or a silylene group are used. In the presence of a polymerization catalyst obtained by contacting a metallocene complex (B) having a ligand in which two (substituted) indenyl groups are bonded by a bridging group with an organoaluminum compound (C), ethylene and an α-olefin Can be used.
The cocatalyst carrier (A) is composed of component (a) diethylzinc, component (b) two types of fluorinated phenol, component (c) water, component (d) inorganic particulate carrier and component (e) 1,1. , 1,3,3,3-hexamethyldisilazane (((CH ₃ ) ₃ Si) ₂ NH) is a carrier obtained by contact.
Examples of the fluorinated phenol of component (b) include pentafluorophenol, 3,5-difluorophenol, 3,4,5-trifluorophenol, 2,4,6-trifluorophenol and the like. From the viewpoint of increasing the activation energy (Ea) of the flow of the ethylene-α-olefin copolymer, increasing the HMw-Index, and increasing the crosslinking density, 3,4,5-trifluorophenol is used alone, or It is preferable to use two types of fluorinated phenols having different numbers of fluorines. When two different kinds of fluorinated phenols are used, for example, pentafluorophenol / 3,4,5-trifluorophenol, pentafluorophenol / 2,4,6-trifluorophenol, pentafluorophenol / 3,5-difluoro A combination of phenol and the like can be mentioned, and a combination of pentafluorophenol / 3,4,5-trifluorophenol is preferable. The molar ratio of the fluorinated phenol having a large number of fluorine and the fluorinated phenol having a small number of fluorine is usually 20/80 to 80/20.
The inorganic compound particles of component (d) are preferably silica gel.
Component (a) diethyl zinc, component (b) 2 types of fluorinated phenol, component (c) The amount of each component used is not particularly limited, but the molar ratio of each component used is the component (a) diethyl. When the molar ratio of zinc: component (b) 2 types of fluorinated phenol: component (c) water = 1: x: y, x and y preferably satisfy the following formula.
| 2-x-2y | ≦ 1
X in the above formula is preferably a number from 0.01 to 1.99, more preferably a number from 0.10 to 1.80, and still more preferably a number from 0.20 to 1.50. Most preferably, the number is 0.30 to 1.00.
The amount of component (d) inorganic fine particle carrier used for component (a) diethyl zinc is included in the particles obtained by contacting component (a) diethyl zinc and component (d) inorganic fine particle carrier. The amount of zinc atoms derived from the component (a) diethylzinc is preferably 0.1 mmol or more and 0.5 to 20 mmol in terms of the number of moles of zinc atoms contained in 1 g of the obtained particles. It is more preferable that The amount of component (e) trimethyldisilazane used for component (d) inorganic particulate carrier is such that component (e) trimethyldisilazane is 0.1 mmol or more per gram of component (d) inorganic particulate carrier. The amount is preferably 0.5 to 20 mmol, and more preferably 0.5 to 20 mmol.
Preferred examples of the metallocene complex (B) having a ligand in which two (substituted) indenyl groups are bonded by a bridging group such as an alkylene group or a silylene group include ethylenebis (1-indenyl) zirconium diphenoxide. .
The organoaluminum compound (C) is preferably triisobutylaluminum or trinormaloctylaluminum.
The amount of the metallocene complex (B) used is preferably 5 × 10 to 1 g of the promoter support (A). ^-6 ~ 5 × 10 ^-4 mol. Also preferred as the amount of organoaluminum compound (C) used.
Alternatively, it is 1 to 2000 in terms of the ratio (Al / M) of the number of moles of aluminum atoms in the organoaluminum compound (C) to the number of moles of metal atoms in the metallocene complex (B).
In the polymerization catalyst obtained by bringing the promoter support (A), the metallocene complex (B), and the organoaluminum compound (C) into contact with each other, the promoter support (A) and the metallocene complex (B) are optionally added. It is good also as a polymerization catalyst which makes an electron-donating compound (D) contact an organic aluminum compound (C).
As a method for producing an ethylene-α-olefin copolymer of component (A), a small amount of olefin is polymerized (hereinafter referred to as prepolymerization) using a solid catalyst component in which a promoter component is supported on a particulate carrier. )) Obtained by polymerizing a small amount of olefin using a co-polymerized solid component, for example, a co-catalyst carrier, a metallocene complex, and a co-catalyst component (such as an alkylating agent such as an organoaluminum compound). A method in which ethylene and an α-olefin are copolymerized using a polymerization solid component as a catalyst component or a catalyst is preferable. When the crosslinked foamed molded article of the present invention is used as a shoe member, it is preferable to add triethylaluminum as a promoter component in order to increase HMw-Index and further improve compression set performance.
Examples of the olefin used in the prepolymerization include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, cyclopentene and cyclohexene. These can be used alone or in combination of two or more. The content of the prepolymerized polymer in the prepolymerized solid component is usually 0.1 to 500 g, preferably 1 to 200 g, per 1 g of the solid catalyst component.
The preliminary polymerization method may be a continuous polymerization method or a batch polymerization method, and examples thereof include a batch type slurry polymerization method, a continuous slurry polymerization method, and a continuous gas phase polymerization method. As a method for introducing catalyst components such as a promoter carrier, a metallocene complex, and other promoter components (such as an alkylating agent such as an organoaluminum compound) into a polymerization reactor for performing prepolymerization, nitrogen, argon, or the like is usually used. A method in which an inert gas such as hydrogen, ethylene, or the like is used without adding moisture, or a method in which each component is dissolved or diluted in a solvent and added in a solution or slurry state is used. In addition, the polymerization temperature in the prepolymerization is usually a temperature lower than the melting point of the prepolymerized polymer, preferably 0 to 100 ° C, more preferably 10 to 70 ° C.
When the prepolymerization is performed by a slurry polymerization method, examples of the solvent include hydrocarbons having 20 or less carbon atoms. For example, saturated aliphatic hydrocarbons such as propane, normal butane, isobutane, normal pentane, isopentane, normal hexane, cyclohexane, heptane, octane, decane, etc .; aromatic hydrocarbons such as benzene, toluene, xylene, etc., which are used alone Alternatively, two or more kinds are used in combination.
As a method for producing an ethylene-α-olefin copolymer, a continuous polymerization method involving the formation of particles of an ethylene-α-olefin copolymer is preferable. For example, a continuous gas phase polymerization method, a continuous slurry polymerization method, a continuous bulk weight It is a legal method, preferably 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 of supplying the prepolymerized prepolymerized solid component to a continuous polymerization reaction tank accompanied by the formation of ethylene-α-olefin copolymer particles, an inert gas such as nitrogen or argon, hydrogen, ethylene or the like is usually used. And a method in which the components are supplied without moisture, and a method in which each component is dissolved or diluted in a solvent and supplied in a solution or slurry state.
When high-pressure low-density polyethylene is used as the ethylene-based polymer, the high-pressure low-density polyethylene is generally a tank-type reactor or a tubular reactor, and a free radical generator such as an organic oxide or oxygen is used. As the polymerization initiator, a resin produced by polymerizing ethylene under a polymerization pressure of 100 to 300 MPa and a polymerization temperature of 130 to 300 ° C. can be used. MFR can also be adjusted by using hydrocarbons such as hydrogen, methane, and ethane as molecular weight regulators.
As a method for producing the crosslinked foamed molded product of the present invention, the same method as the conventional method for producing a crosslinked foamed molded product of ethylene-vinyl acetate copolymer or high-pressure low-density polyethylene can be used.
For example, (1) A foaming agent is blended into an ethylene polymer, and this is uniformly mixed using a ribbon blender or the like, and the resulting mixture is substantially decomposed by an extruder or a calender roll. Melt-kneaded at a temperature and pressure to form a sheet, crosslink by irradiating the sheet-shaped molded body with ionizing radiation, and then heat above the decomposition temperature of the foaming agent to obtain a crosslinked foamed molded body Method, or (2) obtained by blending a foaming agent and a crosslinking agent in an ethylene polymer and melt-mixing the mixture with a mixing roll, kneader, extruder, etc. at a temperature at which the foaming agent and the crosslinking agent are not substantially decomposed. The composition is filled into a mold by an injection molding machine or the like, foamed in a pressurized (holding) / heated state, and then cooled to take out a crosslinked foamed molded product, or (3) an ethylene polymer. To foam The mixture obtained by uniformly mixing using a ribbon blender or the like is melt-kneaded with an extruder or a calender roll at a temperature and pressure at which the foaming agent is not substantially decomposed, and formed into a sheet shape. Examples thereof include a method in which a sheet-like molded body is put in a mold, foamed in a pressurized (holding) / heated state with a pressure press or the like, and then cooled to take out a crosslinked foamed molded body.
Further, for example, (4) obtained by blending a foaming agent and a crosslinking agent in an ethylene polymer, and melt-mixing with a mixing roll, kneader, extruder, etc. at a temperature at which the foaming agent and the crosslinking agent are not substantially decomposed. The composition is further injected into the mold under conditions where the foaming agent and the crosslinking agent are not substantially decomposed, and the foaming agent and the crosslinking agent are decomposed in the mold, for example, a temperature of about 130 to 200 degrees. A method (injection foaming method) in which the resin is crosslinked and foamed while maintaining the above can also be mentioned.
Examples of the foaming agent that can be used in the present invention include a thermally decomposable foaming agent having a decomposition temperature equal to or higher than the melting temperature of the ethylene polymer. For example, azodicarbonamide, barium azodicarboxylate, azobisbutylnitrile, nitrodiguanidine, N, N-dinitrosopentamethylenetetramine, N, N′-dimethyl-N, N′-dinitrosotephthalamide, P-toluene Sulfonyl hydrazide, P, P′-oxybis (benzenesulfonylhydrazide) azobisisobutyronitrile, P, P′-oxybisbenzenesulfonyl semicarbazide, 5-phenyltetrazole, trihydrazinotriazine, hydrazodicarbonamide, etc. These may be used alone or in combination of two or more. Among these, azodicarbonamide or sodium hydrogen carbonate is preferable. In the production of the crosslinked foamed molded article of the present invention, it is preferable that 100 parts by weight of the resin component and 0.5 to 50 parts by weight of the foaming agent are contained with respect to 100 parts by weight of the resin component. The content is more preferably 1 to 15 parts by weight.
When producing a crosslinked foamed molded article, a foaming aid may be blended as necessary. Examples of the foaming aid include compounds mainly composed of urea; metal oxides such as zinc oxide and lead oxide; higher fatty acids such as salicylic acid and stearic acid; and metal compounds of the higher fatty acids. The amount of the foaming aid used is preferably 0.1 to 30% by weight, more preferably 1 to 20% by weight, with the total of the foaming agent and the foaming aid being 100% by weight.
When ionizing radiation is used as a method for crosslinking an ethylene polymer, β rays, γ rays, neutrons, electron beams, and the like can be used. The irradiation amount is preferably in the range of 5 to 20 Mrad.
When a crosslinking agent is used as a method for crosslinking the ethylene polymer, an organic peroxide having a decomposition temperature equal to or higher than the flow start temperature of the ethylene polymer is suitable. For example, dicumyl peroxide, 1,1-ditertiary butyl peroxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-ditertiary butyl peroxyhexane, 2,5-dimethyl-2 , 5-ditertiary butyl peroxyhexyne, α, α-ditertiary butyl peroxyisopropylbenzene, tertiary butyl peroxyketone, tertiary butyl peroxybenzoate, and the like. From the viewpoint of increasing the crosslinking density, the blending ratio of the crosslinking agent is usually 0.02 to 3 parts by weight, preferably 0.05 to 1.5 parts by weight, with the total amount of the resin components being 100 parts by weight. The temperature at which the cross-linking agent does not substantially decompose is a temperature not higher than the one-hour half-life temperature of the cross-linking agent. Usually, the 1-hour half-life temperature of a crosslinking agent is described in MSDS etc. of this crosslinking agent.
The crosslinked foamed molded article of the present invention comprises a heat stabilizer, weathering agent, lubricant, antistatic agent, filler and pigment (metal oxide such as zinc oxide, titanium oxide, calcium oxide, magnesium oxide, silicon oxide; magnesium carbonate, Various additives such as carbonates such as calcium carbonate; fiber materials such as pulp) may be included. Further, as the resin component, a resin such as an ethylene-unsaturated ester copolymer, high-density polyethylene, polypropylene, polybutene, or rubber may be included. In particular, when the cross-linked foamed molded product of the present invention or the compression-crosslinked foamed molded product to be described later is used for a shoe sole or a shoe sole member, it is often necessary to adhere to other members such as rubber and a vinyl chloride sheet. It is preferable to use an ethylene-unsaturated ester copolymer such as a vinyl copolymer in combination with the ethylene polymer. When the ethylene polymer and the ethylene-unsaturated ester copolymer are used in combination, the proportion is 100 parts by weight of the ethylene polymer, and the ethylene-unsaturated ester copolymer is based on 100 parts by weight of the polymer. The combined amount is preferably 25 to 900 parts by weight, and more preferably 40 to 400 parts by weight.
The pressure-crosslinking foaming method, which is one of the methods for producing a crosslinked foamed molded product, will be described. An ethylene polymer, a crosslinking agent, a foaming agent, and the like are melt-kneaded at a temperature at which both components of the crosslinking agent and the foaming agent are not substantially decomposed to produce a foaming resin composition. The foaming resin composition is filled into a mold and 50 kg / cm. ² A cross-linked foamed molded article can be obtained by heating at a temperature equal to or higher than the decomposition temperature of the foaming agent and higher than the decomposition temperature of the cross-linking agent while being pressurized. The clamping pressure of the mold is 50 to 300 kgf / cm ² The pressure holding time is preferably about 10 to 60 minutes.
The crosslinked foamed molded product of the present invention may be a compression crosslinked foamed molded product obtained by further compression molding the crosslinked foamed molded product. Compression molding is usually 130-200 ° C, 30-200 kg / cm ² The process is carried out under the condition of 5 to 60 minutes while applying the above load. Note that a compression-crosslinked foamed molded article is more suitable for a midsole, which is a kind of footwear member.
The crosslinked foamed molded article of the present invention may be used after being cut into a desired shape, or may be used after being buffed.
The crosslinked foamed article of the present invention preferably has a foaming ratio of 4 to 20 times. The surface hardness is preferably in the range of 30-80 in Shore C method hardness.
The crosslinked foamed molded article of the present invention may be laminated with other layers to form a multilayer laminate. The material constituting the other layers includes vinyl chloride resin material, styrene copolymer rubber material, olefin copolymer rubber material (ethylene copolymer rubber material, propylene copolymer rubber material, etc.), natural A leather material, an artificial leather material, a cloth material, and the like can be mentioned, and at least one kind of material is used as these materials.
Examples of a method for producing these multilayer laminates include a method in which the crosslinked foamed molded product of the present invention and another layer formed separately are bonded by heat bonding or a chemical adhesive.
Known chemical adhesives can be used. Of these, urethane chemical adhesives and chloroprene chemical adhesives are particularly preferable. In addition, an undercoat agent called a primer may be applied in advance at the time of bonding with these chemical adhesives.
In a crosslinked foamed molded article, it is known that the crosslinking density is closely related to compression set. In general, the higher the crosslink density, the lower the compression set of the crosslinked foamed molded product.
The crosslinked foamed molded article of the present invention exhibits a good compression set because of its high crosslinking density. Compression set is an index that shows how much the foamed molded body has recovered from compression after being compressed for a certain period of time under certain conditions, released from compression and left for a certain period of time. Emphasized as an indicator of fatigue resistance. The crosslinked foamed molded article of the present invention preferably has a compression set of 30 to 65% when the hardness of the crosslinked foamed molded article is 50 by the Shore C method. Therefore, for example, the crosslinked foamed molded article of the present invention can be suitably used as a member of footwear such as shoes and sandals in a single layer or multilayer form. Examples of the footwear member include a midsole, an outer sole, an insole and the like. In addition to the footwear member, the crosslinked foamed molded article of the present invention is also used for building materials such as a heat insulating material and a cushioning material.

Hereinafter, the present invention will be described in more detail by way of examples and comparative examples.
(1) Melt flow rate (MFR, unit: g / 10 minutes)
According to JIS K7210-1995, it measured by A method on the conditions with a temperature of 190 degreeC and a load of 21.18N.
(2) Density (Unit: kg / m ³ )
After annealing described in JIS K6760-1995, the measurement was performed by an underwater substitution method described in JIS K7112-1980.
(3) Flow activation energy (Ea, unit: kJ / mol)
Using a viscoelasticity measuring device (Rheometrics Mechanical Spectrometer RMS-800 manufactured by Rheometrics), dynamic viscosity-angular frequency curves at 130 ° C, 150 ° C, 170 ° C and 190 ° C were measured under the following measurement conditions. From the obtained dynamic viscosity-angular velocity curve, Rheometrics R. The activation energy (Ea) was determined using 4.4.4.
<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: Under nitrogen
(4) Molecular weight distribution (Mw / Mn)
Using a gel permeation chromatograph (GPC) method, the weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured under the following conditions (1) to (8), and the molecular weight distribution (Mw / Mn) was determined. 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) Apparatus: 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) HMw-Index (unit:%)
It calculated according to the following formula from the chromatogram of Aw (weight average molecular chain length) obtained by GPC method of (4).
HMw-Index (%)
= (Component ratio of LogAw> 4.5 or more) / (Component ratio of LogAw> 4.0 or more) × 100
It means that the higher the HMw-Index, the higher the proportion of the molecular chain component amount having a high molecular weight.
(6) Density of crosslinked foamed molded product (unit: kg / m ³ )
Measured according to ASTM-D297. The smaller this value, the better the lightness.
(7) Appearance of crosslinked foamed molded product (unit: none)
The beauty of the appearance of the obtained cross-linked foamed molded article was determined visually. Judgment was performed in the following three stages.
○: No cracks or tears were observed in the crosslinked foamed molded product, and the surface of the molded product was smooth.
Δ: No cracks or tears were found in the crosslinked foamed molded product, but wrinkles and the like were generated on the surface of the molded product.
X: Cracking, tearing, etc. occurred in the crosslinked foamed molded article, and a beautiful foamed molded article could not be obtained.
(8) Hardness of crosslinked foamed molded product (unit: none)
The surface of the obtained cross-linked foamed molded article (mold installation surface) was measured with a C method hardness meter in accordance with ASTM-D2240.
(9) Compression set of crosslinked foamed molded product (unit:%)
In accordance with JIS K6301-1995, a compression set test was performed under the conditions of 50 ° C./6 hours and 50% compression to determine the compression set. The specimen thickness before and after compression was measured using calipers. The smaller this value, the better the fatigue resistance.
(10) Measurement of gel fraction of crosslinked foamed molded product (unit:%)
1 g of the crosslinked foamed molded product was sealed in a 400-mesh stainless steel wire mesh, and then extracted in 110 ml of boiling xylene for 24 hours. After a predetermined time, the weight of the residue remaining on the wire mesh was measured, and the gel fraction was measured according to the formula of (residue weight, g) / (weight before extraction, = 1 g) × 100 [%]. The smaller this value, the more insoluble components having a network structure are present.
(11) Crosslink density in the crosslinked foamed molded product (unit: mol / kg)
Using a viscoelasticity measuring apparatus (ARES manufactured by TA Instruments), measurement was performed under the following measurement conditions to obtain a crosslinking density.
<Measurement conditions>
Jig: Upper φ8mm, Lower φ25mm Parallel plate
Test piece size: 10 mm x 10 mm, thickness 3 mm
Measurement temperature: 60 ° C
Preheating: 3-5 minutes
Strain rate: 0.1 mm / sec
Compression strain: 50%
Measurement time: 1800 seconds
Measurement atmosphere: under nitrogen
<Calculation method>
Gc = G ₁₈₀₀ (G ₁₈₀₀ : Relaxation elastic modulus when the measurement time is 1800 seconds)
Gc = nRT
R: Gas constant T: Measurement temperature (absolute temperature)
R = 8.31J / K · mol T = 333K
n = Gc / RT
n: Crosslink density (mol / m ³ )
The obtained crosslink density was converted into a crosslink density per unit weight (unit: mol / kg) using the foamed product density.
Example 1
(1) Preparation of promoter support
Silica heated by a nitrogen-replaced stirrer at 300 ° C. under a nitrogen stream (Sypolol 948 manufactured by Devison; 50% volume average particle size = 59 μm; pore volume = 1.68 ml / g; specific surface area = 313m ² / G) 0.36 kg and 3.5 liters of toluene were added and stirred. Thereafter, after cooling to 5 ° C., a mixed solution of 1,1,1,3,3,3-hexamethyldisilazane 0.15 liter and toluene 0.2 liter was kept at 5 ° C. in the reactor. The solution was added dropwise over 30 minutes. 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 component was washed 6 times with 2 liters of toluene. Thereafter, 2 liters of toluene was added to form a slurry, which was allowed to stand overnight.
To the slurry obtained above, 0.27 liter of diethyl zinc in hexane (diethyl zinc concentration: 2 mol / liter) was added and stirred. Thereafter, after cooling to 5 ° C., a mixed solution of 0.05 kg of pentafluorophenol and 0.09 liter of toluene was added dropwise over 60 minutes while maintaining the temperature in 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 cool to 5 ° C, ₂ 7 g of O was added dropwise over 1.5 hours while keeping the temperature in the reactor at 5 ° C. After completion of dropping, the mixture was stirred at 5 ° C. for 1.5 hours, then heated to 55 ° C. and stirred at 55 ° C. for 2 hours. Thereafter, the mixture was cooled to room temperature, and 0.63 liter of diethyl zinc in hexane solution (diethyl zinc concentration: 2 mol / liter) was added. After cooling to 5 ° C., a mixed solution of 94 g of 3,4,5-trifluorophenol and 0.2 liter of toluene was added dropwise over 60 minutes while maintaining the temperature in 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 cool to 5 ° C, ₂ 17 g of O was added dropwise over 1.5 hours while maintaining the temperature in the reactor at 5 ° C. After completion of dropping, the mixture was stirred at 5 ° 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. Then, the mixture is allowed to stand, and the solid component is allowed to settle. When the interface between the precipitated solid component layer and the upper slurry portion is visible, the upper slurry portion is removed, and then the remaining liquid components are removed with a filter. Then, 3 liters of toluene was added and stirred at 95 ° C. for 2 hours. The solid component was allowed to settle, and when the interface between the precipitated solid component layer and the upper slurry portion was seen, the upper slurry portion was removed. Next, at 95 ° C., 4 times with 3 liters of toluene and twice with 3 liters of hexane at room temperature, after adding a solvent and stirring, the mixture is allowed to stand to precipitate the solid component. When the interface with the slurry portion was visible, the upper slurry portion was removed. Subsequently, the remaining liquid components were removed with a filter. Then, the solid component (henceforth a promoter support (a)) was obtained by drying at room temperature under reduced pressure for 1 hour.
(2) Preparation of prepolymerization catalyst component (1)
After adding 80 liters of butane to an autoclave equipped with a stirrer with an internal volume of 210 liters, which was previously purged with nitrogen, 50 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide was added, and 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, 0.03 MPa of ethylene was charged at the gas phase pressure in the autoclave, 0.7 kg of the promoter support (a) was added, and then triethylaluminum was added. Polymerization was started by adding 210 mmol. After 30 minutes while ethylene was continuously supplied at 0.7 kg / Hr, the temperature was raised to 50 ° C., and ethylene and hydrogen were respectively 2.2 kg / Hr and 6.5 liters (room temperature and normal pressure volume) / Hr. A total of 7.5 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 (23.6 g of polyethylene preliminarily polymerized per 1 g of the promoter support (a) ( 1) was obtained.
(3) Production of ethylene-α-olefin copolymer
Using the preliminary polymerization catalyst component (1) obtained above, ethylene and 1-hexene were copolymerized in a continuous fluidized bed gas phase polymerization apparatus to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 84 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 0.318%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 2.1%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. In addition, the prepolymerization catalyst component and 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 is fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hr, a screw rotation 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 (hereinafter referred to as PE (1)) was obtained. The molecular weight distribution (Mw / Mn) of PE (1) was 6.9, and HMw-Index was 11.4%. Table 1 shows the physical properties of PE (1).
(4) Pressure cross-linked foaming
60 parts by weight of PE (1) and ethylene-vinyl acetate copolymer (“H2181” manufactured by The Polyolefin Company; melt flow rate: 2.0 [g / 10 min], density: 940 [kg / m ³ ], Vinyl acetate content: 18 [wt%] hereinafter referred to as EVA) 40 parts by weight, heavy calcium carbonate 10 parts by weight, stearic acid 1.0 part by weight, zinc oxide 1.0 part by weight, chemical foaming agent (Sankyo Chemical Co., Ltd. “Cermic CE” ADCA type chemical foaming agent) 4.2 parts by weight and 0.7 parts by weight of dicumyl peroxide were kneaded at a roll temperature of 120 ° C. using a roll kneader. Kneading was performed for 5 minutes to obtain a resin composition. The resin composition is filled into a 13 cm × 13 cm × 2.0 cm mold, and the temperature is 165 ° C., the time is 30 minutes, and the pressure is 200 kg / cm. ² A cross-linked foamed molded article (1) was obtained by pressure-crosslinking foaming under the conditions of Table 3 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.
Example 2
(1) Pressure cross-linked foaming
Except for changing the amount of the chemical foaming agent to 2.2 parts by weight, a crosslinked foamed molded article (2) was obtained by kneading and pressure-crosslinking foaming under the same conditions as in Example 1. Table 3 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.
Example 3
(1) Production of ethylene-α-olefin copolymer
Using the prepolymerized catalyst component (1) obtained in Example 1, copolymerization of ethylene and 1-hexene was carried out in a continuous fluidized bed gas phase polymerization apparatus to obtain a polymer powder. As polymerization conditions, the polymerization temperature was 84 ° C., the polymerization pressure was 2 MPa, the hydrogen molar ratio to ethylene was 0.38%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 2.0%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. In addition, the prepolymerization catalyst component and 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 is fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hr, a screw rotation 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 (hereinafter referred to as PE (2)) was obtained. The molecular weight distribution (Mw / Mn) of PE (2) was 6.8, and HMw-Index was 11.4%. Table 1 shows the physical properties of PE (2).
(2) Pressure cross-linking foam molding
60 parts by weight of PE (2), 40 parts by weight of EVA, 10 parts by weight of heavy calcium carbonate, 1.0 part by weight of stearic acid, 1.0 part by weight of zinc oxide, 4.7 parts by weight of chemical blowing agent, The resin composition was obtained by kneading 0.7 parts by weight of mill peroxide using a roll kneader under conditions of a roll temperature of 120 ° C. and a kneading time of 5 minutes. The resin composition is filled into a 13 cm × 13 cm × 2.0 cm mold, and the temperature is 165 ° C., the time is 30 minutes, and the pressure is 200 kg / cm. ² A cross-linked foamed molded article (3) was obtained by pressure-crosslinking foaming under the conditions described above. Table 3 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.
Example 4
(1) Preparation of promoter support
In a 50 liter reactor equipped with a nitrogen-replaced stirrer, 24.3 liters of toluene as a solvent and silica heat-treated at 300 ° C. under nitrogen flow as particles (d) (Sypolol 948 manufactured by Devison; average particle size = 58 μm; pore volume = 1.60 ml / g; specific surface area = 316 m ² / G) 2.545 kg was added and stirred. Then, after cooling to 5 ° C., a mixed solution of 823 g of 1,1,1,3,3,3-hexamethyldisilazane and 1.49 liters of toluene was maintained for 30 minutes while maintaining the reactor temperature at 5 ± 3 ° C. It was dripped at. After completion of dropping, the mixture was stirred at 5 ° C. for 1 hour and at 95 ° C. for 3 hours. Thereafter, the obtained solid product was washed 6 times with 95 liters of toluene at 95 ° C. Next, 5.4 liters of toluene was added to form a slurry.
To the toluene slurry obtained in Example 1 (1) above, 4.98 kg of a 32.0 wt% diethylzinc hexane solution as the compound (a) was added and stirred. Then, after cooling to 5 ° C., 2.66 kg of a 3,4,5-trifluorophenol toluene solution prepared as a compound (b) at a concentration of 35.4 wt% was added, and the temperature of the reactor contents was adjusted to 5 ± 3. It was added dropwise over 60 minutes while maintaining the temperature. The molar ratio y of the compound (b) to the compound (a) corresponds to 0.49. After completion of dropping, the mixture was stirred at 5 ° C. for 1 hour and at 40 ° C. for 1 hour. Thereafter, 0.172 liters of water as compound (c) was added dropwise over 90 minutes while maintaining the temperature of the reactor contents at 5 ± 3 ° C. The molar ratio z of the compound (c) to the compound (a) corresponds to 0.74. After completion of dropping, the mixture was stirred at 5 ° C for 1.5 hours, at 40 ° C for 2 hours, and at 80 ° C for 2 hours. Then, it left still and the upper layer part which settled the solid component was removed. Then 13 liters of toluene was added. Then, it heated up at 95 degreeC and stirred for 4 hours. Thereafter, the mixture was allowed to stand at 95 ° C. with 30 liters of toluene four times and at room temperature with 30 liters of hexane three times to precipitate the solid component, and the upper layer portion was removed. The solid component was dried at 40 ° C. under reduced pressure for 6 hours to obtain 4.10 kg of a solid component (hereinafter referred to as promoter support (b)). As a result of elemental analysis, zinc atom = 2.6 mmol / g, fluorine atom = 3.7 mmol / g.
(2) Preparation of prepolymerization catalyst component (2)
After adding 80 liters of butane to an autoclave equipped with a stirrer with an internal volume of 210 liters, which was previously purged with nitrogen, 90 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide 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 a gas phase pressure in the autoclave, and 0.7 kg of the promoter support (b) is added, and then triisobutyl is added. Polymerization was started by adding 263 mmol of aluminum. After 30 minutes while ethylene was continuously supplied at 0.7 kg / Hr, the temperature was raised to 50 ° C., and ethylene and hydrogen were charged at 3.2 kg / Hr and 9.5 liters (room temperature and normal pressure volume) / Hr, respectively. A total of 6 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 the prepolymerized catalyst component (2) in which 24 g of polyethylene is preliminarily polymerized per 1 g of the promoter support (b). Got.
(3) Production of ethylene-α-olefin copolymer
Using the prepolymerized catalyst component (2) obtained above, ethylene and 1-hexene were copolymerized in a continuous fluidized bed gas phase polymerization apparatus 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 0.19%, and the 1-hexene molar ratio to the total of ethylene and 1-hexene was 1.7%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. In addition, the prepolymerization catalyst component and 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 is fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hr, a screw rotation 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 (hereinafter referred to as PE (3)) was obtained. The molecular weight distribution (Mw / Mn) of PE (3) was 4.8, and HMw-Index was 17.9%. Table 1 shows the physical properties of PE (3).
(4) Pressure cross-linked foaming
PE (3) 60 parts, EVA 40 parts, heavy calcium carbonate 10 parts, stearic acid 1.0 part, zinc oxide 1.0 part, chemical foaming agent 2.2 part, The resin composition was obtained by kneading 0.7 parts by weight of mill peroxide using a roll kneader under conditions of a roll temperature of 120 ° C. and a kneading time of 5 minutes. The resin composition is filled into a 13 cm × 13 cm × 2.0 cm mold, and the temperature is 165 ° C., the time is 30 minutes, and the pressure is 200 kg / cm. ² A cross-linked foamed molded article (4) was obtained by pressure-crosslinking foaming under the following conditions. Table 4 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.
Comparative Example 1
(1) Preparation of promoter support
Silica heated by a nitrogen-replaced stirrer at 300 ° C. under a nitrogen stream (Sypolol 948 manufactured by Devison; 50% volume average particle size = 59 μm; pore volume = 1.68 ml / g; specific surface area = 313m ² / G) 0.36 kg and 3.5 liters of toluene were added and stirred. Thereafter, after cooling to 5 ° C., a mixed solution of 1,1,1,3,3,3-hexamethyldisilazane 0.15 liter and toluene 0.2 liter was kept at 5 ° C. in the reactor. The solution was added dropwise over 30 minutes. 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 component was washed 6 times with 2 liters of toluene. Thereafter, 2 liters of toluene was added to form a slurry, which was allowed to stand overnight.
To the slurry obtained above, 0.27 liter of diethyl zinc in hexane (diethyl zinc concentration: 2 mol / liter) was added and stirred. Thereafter, after cooling to 5 ° C., a mixed solution of 0.05 kg of pentafluorophenol and 0.09 liter of toluene was added dropwise over 60 minutes while maintaining the temperature in 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 cool to 5 ° C, ₂ 7 g of O was added dropwise over 1.5 hours while keeping the temperature in the reactor at 5 ° C. After completion of dropping, the mixture was stirred at 5 ° C for 1.5 hours, then heated to 55 ° C, and stirred at 55 ° C for 2 hours. Thereafter, the mixture was cooled to room temperature, and 0.63 liter of diethyl zinc in hexane (diethyl zinc concentration: 2 mol / liter) was added. After cooling to 5 ° C., a mixed solution of 94 g of 3,4,5-trifluorophenol and 0.2 liter of toluene was added dropwise over 60 minutes while maintaining the temperature in 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 cool to 5 ° C, ₂ 17 g of O was added dropwise over 1.5 hours while maintaining the temperature in the reactor at 5 ° C. After completion of dropping, the mixture was stirred at 5 ° 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. Then, the mixture is allowed to stand, and the solid component is allowed to settle. When the interface between the precipitated solid component layer and the upper slurry portion is visible, the upper slurry portion is removed, and then the remaining liquid components are removed with a filter. Then, 3 liters of toluene was added and stirred at 95 ° C. for 2 hours. The solid component was allowed to settle, and when the interface between the precipitated solid component layer and the upper slurry portion was seen, the upper slurry portion was removed. Next, at 95 ° C., 4 times with 3 liters of toluene and twice with 3 liters of hexane at room temperature, after adding a solvent and stirring, the mixture is allowed to stand to precipitate the solid component. When the interface with the slurry portion was visible, the upper slurry portion was removed. Subsequently, the remaining liquid components were removed with a filter. Then, the solid component (henceforth a promoter support (c)) was obtained by drying at room temperature under reduced pressure for 1 hour.
(2) Preparation of prepolymerization catalyst component (3)
After adding 80 liters of butane to an autoclave equipped with a stirrer with an internal volume of 210 liters that has been purged with nitrogen in advance, 101 mmol of racemic-ethylenebis (1-indenyl) zirconium diphenoxide is added, and the autoclave is 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 (c) was added, followed by triisobutyl. Polymerization was started by charging 158 mmol of aluminum. 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, the remaining solids purged with ethylene, butane, hydrogen gas and the like are vacuum-dried at room temperature, and the prepolymerized catalyst component (3) in which 15 g of polyethylene is prepolymerized per 1 g of the promoter support (c). Got.
(3) Production of ethylene-α-olefin copolymer
Using the prepolymerized catalyst component (3) obtained above, ethylene and 1-hexene were copolymerized in a continuous fluidized bed gas phase polymerization apparatus to obtain a polymer powder. The polymerization conditions were a polymerization temperature of 80 ° C., a polymerization pressure of 2 MPa, a hydrogen molar ratio to ethylene of 1.6%, and a 1-hexene molar ratio to the total of ethylene and 1-hexene of 1.5%. During the polymerization, ethylene, 1-hexene and hydrogen were continuously supplied in order to keep the gas composition constant. In addition, the prepolymerization catalyst component and 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 is fed using an extruder (LCM50 manufactured by Kobe Steel, Ltd.) at a feed rate of 50 kg / hr, a screw rotation 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 (hereinafter referred to as PE (4)) was obtained. The results of physical property evaluation of the obtained copolymer are shown in Table 1. The molecular weight distribution (Mw / Mn) of PE (4) was 8.8, and HMw-Index was 5.4%. Table 2 shows the physical properties of PE (4).
(4) Pressure cross-linked foaming
60 parts by weight of PE (4), 40 parts by weight of EVA, 10 parts by weight of heavy calcium carbonate, 1.0 part by weight of stearic acid, 1.0 part by weight of zinc oxide, 2.6 parts by weight of chemical foaming agent, 0.9 parts by weight of mill peroxide was kneaded using a roll kneader under conditions of a roll temperature of 120 ° C. and a kneading time of 5 minutes to obtain a resin composition. The resin composition is filled into a 13 cm × 13 cm × 2.0 cm mold, and the temperature is 165 ° C., the time is 30 minutes, and the pressure is 200 kg / cm. ² A cross-linked foamed molded article (5) was obtained by pressure-crosslinking foaming under the conditions described above. Table 4 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.
Comparative Example 2
(1) Pressure cross-linked foaming
40 parts by weight of ethylene-1-hexene copolymer (Sumikacene E FV401 manufactured by Sumitomo Chemical Co., Ltd., hereinafter PE (5), physical properties are shown in Table 2), 60 parts by weight of EVA, 10 parts by weight of heavy calcium carbonate, stearin 1.0 parts by weight of acid, 1.0 part by weight of zinc oxide, 2.6 parts by weight of chemical foaming agent, and 0.7 parts by weight of dicumyl peroxide were mixed at a roll temperature of 120 ° C. using a roll kneader. The resin composition was obtained by kneading under a condition of kneading time of 5 minutes. The resin composition is filled into a 13 cm × 13 cm × 2.0 cm mold, and the temperature is 165 ° C., the time is 30 minutes, and the pressure is 200 kg / cm. ² A cross-linked foamed molded article (6) was obtained by pressure-crosslinking foaming under the conditions described above. Table 4 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.
Comparative Example 3
(1) Pressure cross-linked foaming
PE (5) 20 parts by weight EVA 80 parts by weight heavy calcium carbonate 10 parts by weight stearic acid 1.0 part by weight zinc oxide 1.0 part by weight chemical foaming agent 3.0 part by weight The resin composition was obtained by kneading 0.7 parts by weight of mill peroxide with a roll kneader under conditions of a roll temperature of 120 ° C. and a kneading time of 5 minutes. The resin composition is filled into a 13 cm × 13 cm × 2.0 cm mold, and the temperature is 165 ° C., the time is 30 minutes, and the pressure is 200 kg / cm. ² A cross-linked foamed molded article (7) was obtained by pressure-crosslinking foaming under the conditions described above. Table 5 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.
Comparative Example 4
(1) Pressure cross-linked foaming
60 parts by weight of ethylene-1-hexene copolymer (Sumikacene E FV403 manufactured by Sumitomo Chemical Co., Ltd., hereinafter PE (6), physical properties are shown in Table 2), 40 parts by weight of EVA, 10 parts by weight of heavy calcium carbonate, stearin 1.0 parts by weight of acid, 1.0 part by weight of zinc oxide, 2.6 parts by weight of chemical foaming agent, and 0.7 parts by weight of dicumyl peroxide were mixed at a roll temperature of 120 ° C. using a roll kneader. The resin composition was obtained by kneading under a condition of kneading time of 5 minutes. The resin composition is filled into a 13 cm × 13 cm × 2.0 cm mold, and the temperature is 165 ° C., the time is 30 minutes, and the pressure is 200 kg / cm. ² A cross-linked foamed molded article (8) was obtained by pressure-crosslinking foaming under the conditions of Table 5 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.
Comparative Example 5
(1) Pressure cross-linked foaming
EVA 100 parts by weight, heavy calcium carbonate 10 parts by weight, stearic acid 1.0 part by weight, zinc oxide 1.0 part by weight, chemical foaming agent 2.6 parts by weight, dicumyl peroxide 0.7 part by weight Were kneaded under the conditions of a roll temperature of 120 ° C. and a kneading time of 5 minutes using a roll kneader to obtain a resin composition. The resin composition is filled into a 13 cm × 13 cm × 2.0 cm mold, and the temperature is 165 ° C., the time is 30 minutes, and the pressure is 200 kg / cm. ² A crosslinked foamed molded article (9) was obtained by pressure-crosslinking foaming under the following conditions. Table 5 shows the physical property evaluation results of the obtained cross-linked foamed molded article, and the cross-linking density and gel fraction evaluation results.

By using the measurement method of the present invention, the crosslink density of a cross-linked foamed molded article made of a polyethylene polymer can be calculated easily and accurately. The accuracy of the crosslink density measured by the method of the present invention is that, as shown in FIGS. 1 and 2, the correlation with the compression set of the foamed molded product is one of known methods for identifying effective network chain structures. It is clear from the fact that the crosslink density measured by the method of the present invention is better than the gel fraction.

According to the present invention, the crosslink density of a cross-linked foamed molded article made of a thermoplastic polymer can be accurately measured. In particular, the measuring method of the present invention is suitable for measuring the crosslinking density of a crosslinked foamed product made of an ethylene polymer, which has conventionally been difficult to accurately measure the crosslinking density. Moreover, the crosslinked foamed molded product made of an ethylene polymer of the present invention has a high crosslinking density and excellent compression set performance, and is suitable as a member for shoes.

Claims

A cross-linked foamed molded product made of an ethylene polymer, wherein the cross-linked foamed molded product is subjected to compression deformation under the conditions of a measurement temperature of 60 ° C., a compression strain of 50%, and a measurement time of 1800 seconds. A cross-linked foamed product made of an ethylene polymer having a cross-link density of 0.30 mol / kg or more determined by using the relaxation elastic modulus obtained from the stress relaxation measurement.
2. The ethylene polymer according to claim 1, wherein the ethylene polymer used for producing the cross-linked foamed product made of an ethylene polymer is a high-pressure low-density polyethylene and / or an ethylene-α-olefin copolymer. Cross-linked foamed molded product.
The ethylene-α-olefin copolymer has a monomer unit based on ethylene and a monomer unit based on an α-olefin having 3 to 20 carbon atoms, and
The melt flow rate (MFR) of the ethylene-α-olefin copolymer is 0.01 to 3.0 g / 10 minutes, the flow activation energy is 40 kJ / mol or more, and gel permeation chromatography. The crosslinked foamed article made of an ethylene polymer according to claim 2, wherein HMw-Index (High Molecular Index) measured by a graph (GPC) method is 8.0% or more.
A member for shoes comprising the crosslinked foamed product made of an ethylene polymer according to any one of claims 1 to 3.
A method for measuring the crosslinking density of a thermoplastic polymer crosslinked foamed molded article,
Heating the thermoplastic polymer cross-linked foam to a predetermined temperature;
A pressure is applied to the crosslinked foamed molded product made of a thermoplastic polymer maintained at a predetermined temperature to compressively deform the crosslinked foamed molded product, and while maintaining the amount of compressive strain of the crosslinked foamed molded product constant, Measuring stress relaxation;
A step of obtaining a relaxation elastic modulus Gc from stress relaxation, wherein Gc is an elastic modulus when the stress of the crosslinked foamed molded article becomes constant,
Calculating the crosslinking density of the thermoplastic polymer crosslinked foam from the Gc by the following formula.
n = Gc / RT
n: Crosslink density R: Gas constant T: Measurement temperature
The method for measuring the crosslinking density of a thermoplastic polymer crosslinked foamed molded product according to claim 5, wherein the thermoplastic polymer used for producing the thermoplastic polymer crosslinked foamed molded product is an ethylene polymer.
The method for measuring a crosslinking density of a thermoplastic polymer crosslinked foamed molded article according to claim 6, wherein the ethylene polymer is a high-pressure low-density polyethylene and / or an ethylene-α-olefin copolymer.
The method for measuring the crosslinking density of a thermoplastic polymer crosslinked foam according to claim 5, wherein the thermoplastic polymer crosslinked foam is a foam formed from a thermoplastic polymer crosslinked with an organic peroxide. .