JP2019048967A - Ultrahigh molecular weight ethylene polymerization powder and molded body using ultrahigh molecular weight ethylene polymerization powder - Google Patents

Abstract

To provide ultrahigh molecular weight ethylene polymerization powder capable of improving productivity while enhancing a performance of a molded body, and a molded body obtained using the ultrahigh molecular weight ethylene polymerization powder.SOLUTION: Ultrahigh molecular weight ethylene polymerization powder includes an ethylene unit and/or an ethylene unit and an α-olefin unit having 3-8 carbon atoms as a constitutional unit, in which a viscosity-average molecular weight is 100,000-10,000,000, a titanium element content by an inductive coupling plasma mass spectrometer (ICP/MS) is 20 ppm or less, and an isothermal crystallization time is less than 6 minutes. A molded body is obtained by using the ultrahigh molecular weight ethylene polymerization powder.SELECTED DRAWING: None

Description

  The present invention relates to an ultrahigh molecular weight ethylene-based polymer powder and a molded article using the ultrahigh molecular weight ethylene-based polymer powder.

  In the past, ultra high molecular weight olefins, especially ultra high molecular weight polyethylene, have higher molecular weight than general-purpose polyethylene, so they are excellent in stretchability, high in strength, high in chemical stability, and excellent in long-term reliability. For the reason, it is used as a raw material of molded articles such as microporous films and separators of separators of secondary batteries represented by lead storage batteries and lithium ion batteries.

  In addition, ultrahigh molecular weight olefins, in particular ultrahigh molecular weight polyethylene, are excellent in various properties such as impact resistance, abrasion resistance, slidability, low temperature characteristics, chemical resistance, etc., compared to general-purpose polyethylene. It is also used for hoppers, lining materials such as chutes, bearings, gears, roller guide rails, or moldings such as bone substitutes, bone conductive materials and bone inducers.

  By the way, since these ultrahigh molecular weight polyethylenes have a high molecular weight, extrusion molding with a resin alone may be difficult. Therefore, when manufacturing separator films for secondary batteries, fibers and the like, ultrahigh molecular weight polyethylene is often kneaded and extruded at high temperature, for example, in a state of being dissolved in a solvent in an extruder ( Hereinafter, this method is also expressed as wet extrusion).

  Further, for the same reason as described above, molding is often performed by compression molding (press molding) or ram extrusion. It is important to make both impact resistance and abrasion resistance compatible with each other in compression molded products and ram extruded products. Examples of methods for achieving these characteristics are disclosed in Patent Documents 1 to 3.

Japanese Patent Application Publication No. 2007-23171 Patent No. 4173444 JP, 2015-157905, A

  Here, in recent years, in the case of molded articles such as separator films for secondary batteries, fibers, compression molded articles, ram extruded articles, etc. using ultra-high molecular weight polyethylene, the productivity is further improved while the performance is improved. There is a growing demand for

  The present invention has been made in view of the above problems, and the performance of ultra high molecular weight polyethylene, for example, molded articles such as separator films for secondary batteries, fibers, compression molded articles, ram extruded articles, etc. An object of the present invention is to provide an ultra-high molecular weight ethylene-based polymer powder and a molded article using the ultra-high molecular weight ethylene-based polymer powder, which can improve productivity while improving the properties.

  Therefore, the present inventors have intensively studied to achieve the above-mentioned task. As a result, it has been surprisingly found that the above-mentioned problems can be solved by using a specific ultrahigh molecular weight ethylene-based polymer powder, and the present invention has been completed. Specifically, by using a specific ultrahigh molecular weight ethylene-based polymer powder, the cooling process time in the production of the molded article, in particular, the separator film for secondary battery, fiber, compression molded article, ram extruded product is shortened In addition, it has been found that the swelling failure is likely to occur in the conventional ultra-high molecular weight ethylene-based polymer powder during wet extrusion, but the swelling state is good and the extrusion time is shortened. Furthermore, for example, in the separator membrane for a secondary battery, although it was difficult with the techniques disclosed in the above-mentioned Patent Documents 1 to 3, it is possible to use a specific ultrahigh molecular weight ethylene-based polymer powder for a secondary battery It has been found that the average pore diameter of the separator membrane can be reduced and made uniform, whereby the performance of the separator membrane for a secondary battery can be improved.

That is, the present invention is as follows.
[1]
And ethylene units and / or ethylene units and α-olefin units having 3 to 8 carbon atoms as constituent units,
Viscosity average molecular weight is 100,000 or more and 10,000,000 or less,
The elemental titanium content by inductively coupled plasma mass spectrometry (ICP / MS) is 20 ppm or less,
In the measurement of the following isothermal crystallization time measurement conditions using a differential scanning calorimeter, the time when the temperature reached 126 ° C. in step A3 is taken as the starting point (0 minute), and the time when the exothermic peak top due to crystallization is obtained Said isothermal crystallization time is less than 6 minutes when said is an isothermal crystallization time,
Ultra high molecular weight ethylene polymer powder.
(Isothermal crystallization time measurement conditions)
Step A1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a temperature rising rate of 10 ° C./min Step A2: Hold at 180 ° C. for 30 minutes, then lower the temperature to 126 ° C. at 80 ° C./min. : Hold at 126 ° C [2]
The ultrahigh molecular weight ethylene polymer powder according to the above [1], wherein the content of titanium element by ICP / MS is 15 ppm or less.
[3]
The ultrahigh molecular weight ethylene polymer powder according to the above [1], wherein the titanium element content by ICP / MS is 7 ppm or less.
[4]
The ultrahigh molecular weight ethylene polymer powder according to any one of the above [1] to [3], wherein the aluminum element content by ICP / MS is 10 ppm or less.
[5]
In the measurement of the following heat of fusion (ΔH2) measurement conditions using a differential scanning calorimeter, the heat of fusion (ΔH2) in the temperature rising process of step B3 is 250 J / g or less according to the above [1] to [4] The ultra-high molecular weight ethylene-based polymer powder according to any of the above.
(The heat of fusion (ΔH2) measurement condition)
Step B1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a heating rate of 10 ° C./min Step B2: Hold at 180 ° C. for 5 minutes, then lower the temperature to 50 ° C. at 10 ° C./min : Hold at 50 ° C for 5 minutes and then raise the temperature to 180 ° C at a heating rate of 10 ° C / min [6]
The tap density is 0.35 g / cm ³ or more and 0.70 g / cm ³ or less, and the bulk density is 0.40 g / cm 3 or more and 0.60 g / cm 3 or less, in the above [1] to [5] Ultrahigh molecular weight ethylene-based polymer powder according to any one of the above.
[7]
The ultrahigh molecular weight ethylene polymer powder according to the above [6], wherein the ratio of tap density to bulk density is 1.10 or more and 1.50 or less.
[8]
The ultrahigh molecular weight ethylene polymer powder according to any one of the above [1] to [7], which has an average particle size of 50 μm to 200 μm.
[9]
The molded object using the ultra-high molecular weight ethylene polymer powder in any one of said [1]-[8].
[10]
The molded object according to the above [9], which is a separator film or fiber for a secondary battery obtained by a wet extrusion method.
[11]
The molded object of the said [10] description whose secondary battery is a lithium ion secondary battery or lead acid battery.
[12]
The molded article according to the above [10], wherein the product using fiber is a rope, a net, a bulletproof clothing, a protective clothing, a protective glove, a fiber reinforced concrete product or a helmet.
[13]
The molded article according to the above [9], which is used for lining applications, bearings, gears, roller guide rails, bone substitutes, bone conductive materials, or bone inducers.

  According to the present invention, it is possible to provide an ultra-high molecular weight ethylene-based polymer powder capable of improving productivity while improving the performance of a molded body, and a molded body obtained using the ultra-high molecular weight ethylene-based polymer powder. It can be realized.

Hereinafter, although a mode for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail, the present invention is not limited to this. Various modifications are possible without departing from the scope of the invention.
[Ultra-high molecular weight ethylene polymer powder]
The ultrahigh molecular weight ethylene polymer powder of the present embodiment has an ethylene unit and / or an ethylene unit and an α-olefin unit having 3 to 8 carbon atoms as a constitutional unit, and has a viscosity average molecular weight of 100,000 to 10 , 000,000 or less, titanium element content is 20 ppm or less by inductively coupled plasma mass spectrometry (ICP / MS), and measurement of the following isothermal crystallization time measurement conditions using a differential scanning calorimeter: The isothermal crystallization time is less than 6 minutes when the time when the exothermic peak top due to crystallization is obtained is the isothermal crystallization time (minutes) with the time to reach 126 ° C. of A3 as the starting point (0 minute) It is. The ultrahigh molecular weight ethylene polymer powder can improve the productivity of the molded body while improving the performance of the molded body.
(Isothermal crystallization time measurement conditions)
Step A1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a temperature rising rate of 10 ° C./min Step A2: Hold at 180 ° C. for 30 minutes, then lower the temperature to 126 ° C. at 80 ° C./min. : Maintained at 126 ° C. In the present specification, the nomenclature of each monomer unit constituting the polymer follows the nomenclature of the monomer from which the monomer unit is derived. For example, "ethylene unit" means a constituent unit of a polymer produced as a result of polymerizing ethylene which is a monomer, and the structure is a molecular structure in which two carbons of ethylene form a polymer main chain is there. Further, "α-olefin unit" means a constituent unit of a polymer produced as a result of polymerizing α-olefin which is a monomer, and in the structure, two carbons of olefin derived from α-olefin are heavy It is a molecular structure that is a united main chain.

The ultrahigh molecular weight ethylene-based polymer powder is not particularly limited as long as it contains an ethylene unit and / or an ethylene unit and an α-olefin unit having 3 to 8 carbon atoms. The α-olefin having 3 or more and 8 or less carbon atoms is not particularly limited as long as it is copolymerizable with ethylene, but specifically, a linear, branched or cyclic α-olefin, a formula CH ₂ CHCHR ¹ (herein And R ¹ is an aryl group having 1 to 6 carbon atoms) and at least one selected from the group consisting of linear, branched or cyclic dienes having 4 to 7 carbon atoms And alpha-olefins of Among these, as the α-olefin, propylene and 1-butene are preferable from the viewpoints of the abrasion resistance, heat resistance and strength of the molded body.

[Viscosity average molecular weight]
The viscosity average molecular weight (Mv) is 100,000 or more and 10,000,000 or less, more preferably 150,000 or more and 9,500,000 or less, and more preferably 200,000 or more and 9,000,000 or less. When Mv is 100,000 or more, the strength of various molded articles is further improved. In addition, when Mv is 10,000,000 or less, processing characteristics of various molded articles are further improved. Furthermore, when the Mv is in the above range, the powder productivity is excellent. The ultrahigh molecular weight ethylene-based polymer powder having such properties can be suitably used for wet extrusion, compression molding (press molding), ram extrusion and the like, and the resulting molded body is suitably used in a wide range of applications. be able to.

  As a method of controlling the viscosity average molecular weight (Mv) in the above range, it is possible to change the polymerization temperature of the reactor when polymerizing the ultrahigh molecular weight ethylene polymer powder. Generally, the higher the polymerization temperature, the lower the Mv, and the lower the polymerization temperature, the higher the Mv. Moreover, as another method of making Mv into the said range, changing the organometallic compound seed | species as a co-catalyst added when supermolecular-weight ethylene polymer powder is superposed | polymerized is mentioned. In addition, a chain transfer agent may be added when polymerizing the ultrahigh molecular weight polyethylene copolymer. By adding the chain transfer agent in this manner, the Mv of the ultrahigh molecular weight ethylene-based polymer powder produced at the same polymerization temperature tends to be low.

The viscosity average molecular weight (Mv) of the ultra-high molecular weight ethylene-based polymer powder is obtained by dissolving the ultra-high molecular weight ethylene-based polymer powder in decahydronaphthalene solution at different concentrations and extrapolating the reduced viscosity obtained at 135 ° C to 0 concentration. From the determined intrinsic viscosity [η] (dL / g), the following formula A can be used. More specifically, it can be determined by the method described in the examples.
Mv = (5.34 × 10 ⁴ ) × [η] ^1.49 ··· Formula A

[Content of Ethylene Unit, α-Olefin Unit]
99 mol% or more and 100 mol% or less are preferable with respect to the total amount of an ethylene unit and an alpha-olefin unit, 99. 2 mol% or more and 100 mol% or less are more preferable, and 99.4 mol% or more and 100 mol% or less More preferable. When the content of the ethylene unit is in the above range, the heat resistance and / or the strength of the molded article tends to be more excellent.

In addition, the measurement of content of an alpha-olefin unit is G. J. The method is carried out according to the method disclosed in Ray et al., Macromolecules, 10, 773 (1977), and the content of α-olefin units is determined using the signal of methylene carbon observed by ¹³ C-NMR spectrum. It can be calculated from the intensity. More specifically, it can be measured by the method described in the examples.

[Element content of titanium]
The elemental titanium content is defined as a value obtained by measurement using an inductively coupled plasma mass spectrometer (ICP / MS). The titanium element content is 20 ppm or less, preferably 15 ppm or less, and more preferably 7 ppm or less. If the titanium content is 20 ppm or less, not only the cooling step time in the production of molded articles, particularly separator films for secondary batteries, fibers, compression molded articles, and ram extruded articles is shortened, but also solvents during wet extrusion Swelling failure of the ultra-high molecular weight ethylene polymer powder is difficult to occur, and a good swollen state can be obtained. As a result, the productivity of the molded body can be improved. In addition, when the titanium element content is 20 ppm or less, the average pore diameter of the secondary battery separator membrane can be reduced and made uniform, and hence the performance of the secondary battery separator membrane can be improved. Can. In addition, the titanium element content contained in the ultra-high molecular weight ethylene-based polymer powder can be controlled by the productivity of the ultra-high molecular weight ethylene-based polymer powder per unit catalyst, and the content is reduced by increasing the productivity. It is possible. In addition, the measurement of titanium element content can be performed by the method as described in an Example.

[Isothermal crystallization time]
The isothermal crystallization time is the time until an exothermic peak top due to crystallization is obtained at 126 ° C. Specifically, when measured under the following measurement conditions using a differential scanning calorimeter (DSC), the time when the temperature reached 126 ° C. is taken as the starting point (0 minute), and the exothermic peak top due to crystallization is obtained The time to be done is defined as the isothermal crystallization time.
Step A1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a temperature rising rate of 10 ° C./min Step A2: Hold at 180 ° C. for 30 minutes, then lower the temperature to 126 ° C. at 80 ° C./min. : Kept at 126 ° C.

  The isothermal crystallization time is less than 6 minutes, preferably 5.5 minutes or less, and more preferably 5.2 minutes or less. If the isothermal crystallization time is less than 6 minutes, not only the cooling step time in the production of molded articles, particularly separator membranes for secondary batteries, fibers, compression molded articles, and ram extruded articles, but also wet extrusion is shortened. The swelling failure of the ultra-high molecular weight ethylene-based polymer powder in the solvent is less likely to occur, and the average pore diameter of the secondary battery separator membrane can be reduced and made uniform.

  As a method of controlling the isothermal crystallization time in the above range, the strength at which the catalyst is stirred in the catalyst storage reactor is important. Specifically, it is achieved by vigorously stirring in a catalyst storage reactor diluted with an inert hydrocarbon. More specifically, four or more, more preferably six or more, still more preferably eight or more stirring blades are used in the reactor (for example, an autoclave of 8 L), and the rotational speed of the stirring blades is 60 rpm or more. More preferably, the rotation speed is 90 rpm, more preferably 120 rpm or more, and a mixer may be provided in the liquid transfer route. In addition, when stirring the catalyst in the catalyst storage reactor, it is also important not to slow the addition rate of the catalyst raw material in order to control the isothermal crystallization time within the above range.

[Aluminum element content]
The elemental aluminum content is defined as a value obtained by measurement using an inductively coupled plasma mass spectrometer (ICP / MS). The aluminum element content is preferably 10 ppm or less, more preferably 6 ppm or less, and still more preferably 5 ppm or less. If the aluminum element content is 10 ppm or less, not only the cooling process time in the production of separator films for secondary batteries, fibers, compression molded products, ram extruded products is shortened, but also ultra-high to solvent during wet extrusion The swelling failure of the molecular weight ethylene-based polymer powder is less likely to occur, and the average pore diameter of the secondary battery separator membrane can be reduced and made uniform. The content of aluminum element contained in the ultra-high molecular weight ethylene-based polymer powder can be controlled by the productivity of the ultra-high molecular weight ethylene-based polymer powder per unit catalyst, and the content is reduced by increasing the productivity. It is possible. In addition, the measurement of aluminum element content can be performed by the method as described in an Example.

[Heat of fusion (ΔH2)]
In the measurement of the following heat of fusion (ΔH2) measurement conditions using a differential scanning calorimeter, the heat of fusion in the temperature rising process of step B3 (heat of fusion in the second temperature rising process) is defined as the heat of fusion (ΔH2).
(The heat of fusion (ΔH2) measurement condition)
Step B1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a heating rate of 10 ° C./min Step B2: Hold at 180 ° C. for 5 minutes, then lower the temperature to 50 ° C. at 10 ° C./min : Holds at 50 ° C for 5 minutes and then heats up to 180 ° C at 10 ° C / min.

  At this time, the heat of fusion (ΔH 2) is preferably 250 J / g or less, more preferably 50 J / g or more and 240 J / g or less, and still more preferably 100 J / g or more and 230 J / g or less. When the heat of fusion (ΔH 2) is 250 J / g or less, the heat resistance of various molded articles can be secured.

[Tap density and bulk density]
The tap density of the ultrahigh molecular weight ethylene polymer powder is preferably 0.35 g / cm ³ or more and 0.70 g / cm ³ or less, more preferably 0.36 g / cm ³ or more and 0.65 g / cm ³ or less. More preferably, it is 0.37 g / cm ³ or more and 0.60 g / cm ³ or less. When the tap density of the ultra-high molecular weight ethylene-based polymer powder is in the above range, the powder is sufficiently filled at the time of molding, so that a uniform molded body tends to be obtained.

The bulk density of the ultrahigh molecular weight ethylene polymer powder is preferably 0.40 g / cm ³ or more and 0.60 g / cm ³ or less, more preferably 0.40 g / cm ³ or more and 0.58 g / cm ³ or less More preferably, it is 0.40 g / cm ³ or more and 0.55 g / cm ³ or less. When the bulk density is 0.40 g / cm ³ or more, the flowability of the ultrahigh molecular weight ethylene polymer powder is sufficiently high, the handling property is excellent, the feed to various molding machines is stable, and the size of the molded product Tend to be stable. On the other hand, when the bulk density of the ultra-high molecular weight ethylene-based polymer powder is 0.60 g / cm ³ or less, it tends to be excellent in productivity etc. and show better processing applicability when processing a molded product etc. is there.

  The ratio of tap density to bulk density is preferably 1.10 or more and 1.50 or less, more preferably 1.10 or more and 1.48 or less, and still more preferably 1.10 or more and 1.45 or less. is there. When the ratio of the tap density to the bulk density is in the above range, the balance of processing applicability and dimensional stability of various molded articles tends to be more excellent.

  Generally, the bulk density varies depending on the catalyst used, but can be controlled by the productivity of the ultrahigh molecular weight ethylene polymer powder per unit catalyst. The bulk density of the ultra-high molecular weight ethylene-based polymer powder can be controlled by the polymerization temperature at the time of polymerizing the ultra-high molecular weight ethylene-based polymer powder, and the bulk density may be reduced by increasing the polymerization temperature. It is possible. The bulk density of the ultrahigh molecular weight ethylene polymer powder can also be controlled by the slurry concentration in the polymerizer, and the bulk density can be increased by increasing the slurry concentration. The bulk density of the ultrahigh molecular weight ethylene polymer powder can be measured by the method described in the examples.

  Moreover, in order to make tap density into the above-mentioned range, it is effective to suppress electrostatic adhesion of the polymer to a polymerization reactor. Specifically, although disclosed in [0081] of Patent Document 3 described above, the amount of Stadis 450 added is preferably 20 ppm or more and 50 ppm or less.

  In addition, the ratio of tap density to bulk density can also be controlled by the above-mentioned method, and it is also preferable to blend a lubricant such as calcium stearate described later.

[Average particle size]
The average particle diameter of the ultrahigh molecular weight ethylene polymer powder is preferably 50 μm to 200 μm, more preferably 60 μm to 190 μm, and still more preferably 70 μm to 180 μm. When the average particle diameter of the ultra-high molecular weight ethylene-based polymer powder is 50 μm or more, handling properties such as charging of the ultra-high-molecular-weight ethylene-based polymer powder into a hopper or weighing from the hopper tend to be better. On the other hand, when the average particle diameter is 200 μm or less, the processability such as productivity tends to be more excellent in various molding processes. The average particle size of the ultra-high molecular weight ethylene polymer powder can be controlled so that the average particle size of the powder can be reduced by reducing the particle size of the catalyst used, and the ultra-high per unit amount of catalyst can be controlled. It is also possible to control so that the average particle size of the powder can be reduced by increasing the productivity of the molecular weight ethylene polymer powder. The average particle size of the ultrahigh molecular weight ethylene polymer powder can be measured by the method described in the examples described later.

  The ultra-high molecular weight ethylene-based polymer powder may be molded with various molding machines as it is, after being mixed with the organic peroxide into the ultra-high molecular weight ethylene-based polymer powder, it is molded with various molding machines. I don't care. There is a problem that cross-linking unevenness occurs when molding processing is performed with various molding machines after mixing with the organic peroxide, but in the case of the ultrahigh molecular weight ethylene-based polymer powder of the embodiment of the present invention, it exists in the molecular chain The crosslinking reaction preferentially proceeds on the tertiary carbon derived from the trace amount of .alpha.-olefin, and the uniform crosslinking reaction proceeds. This further improves the wear resistance of the molded article.

  The organic peroxide (organic peroxide crosslinking agent) used when molding the ultra-high molecular weight ethylene-based polymer powder contributes to the cross-linking of the above-mentioned ultra-high molecular weight ethylene-based polymer powder, and the atomic group -O in the molecule The organic substance is not particularly limited as long as it is an organic substance having -O-, and examples thereof include: organic peroxides such as dialkyl peroxides, diacyl peroxides, hydroperoxides, hydroperoxides and ketone peroxides; organic peresters such as alkyl peresters; The organic peroxide is not particularly limited. Specifically, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2 5-Dimethyl-2,5-di- (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3 3,5-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl perle Benzoate, tert-butyl peroxy Isopropyl carbonate, diacetyl peroxide, lauroyl peroxide, tert- butyl cumyl peroxide, alpha,. Alpha .'- di (tert- butylperoxy) diisopropylbenzene and the like. Among these, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (trade name "Perhexa 25B" manufactured by Nippon Oil and Fats Co., Ltd.), 2,5-dimethyl-2,5-bis (T-Butyloxy) Hexin-3 (trade name "Perhexin 25B" manufactured by Nippon Oil and Fats Co., Ltd.), dicumyl peroxide, 1,1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane is preferable .

  The mixing of the ultrahigh molecular weight ethylene polymer powder and the organic peroxide can be carried out using a conventional mixer. For example, mixing by a stirrer such as a Henschel mixer or rotation by a blender is preferable. The stirring and mixing conditions in this case are not determined indiscriminately because they depend on conditions such as temperature, pressure, and sales expansion speed, but for example, at normal temperature and normal pressure, the speed is 50 rpm / min to 800 rpm / min for 1 min. The mixture may be stirred and mixed for about 10 minutes. In addition, the stirring / mixing speed may be appropriately changed, for example, mixing may be carried out for a few minutes at first at low speed, and it may be stirred / mixed for several minutes at a higher speed when the compounding components are uniformly mixed to some extent. . The organic peroxide to be mixed with the ultrahigh molecular weight ethylene polymer powder may be used as it is or may be added after being dissolved in a hydrocarbon solvent or the like.

[Method for producing ultra-high molecular weight ethylene polymer powder]
The ultrahigh molecular weight ethylene-based polymer powder is not particularly limited, and can be produced using a general Ziegler-Natta catalyst or a metallocene catalyst, and among them, it is preferable to produce using a Ziegler-Natta catalyst. The Ziegler-Natta catalyst is disclosed in [0032] to [0068] of the aforementioned Patent Document 3.

  When adding a solid catalyst component and an organometallic compound component (hereinafter, "solid catalyst component and organometallic compound component" are also referred to as "catalyst") into a polymerization system under ethylene-based polymerization conditions, Both may be separately added to the polymerization system, or may be added to the polymerization system after mixing both in advance. Further, the ratio of the two to be combined is not particularly limited, but the organic metal compound component is preferably 0.01 mmol or more and 1,000 mmol or less, more preferably 0.1 mmol or more and 500 mmol or less, and more preferably 1 mmol or more and 100 mmol or less. More preferable. Another purpose of mixing the two is to prevent electrostatic adhesion to a storage tank, piping, and the like.

  The polymerization method in the method for producing the ultrahigh molecular weight ethylene polymer powder includes a method of (co) polymerizing a monomer containing ethylene or an α-olefin having 3 to 8 carbon atoms by a suspension polymerization method. The polymerization by the suspension polymerization method is preferable in that the heat of polymerization can be efficiently removed. In the suspension polymerization method, an inert hydrocarbon medium can be used as a medium, and further, an olefin itself can also be used as a solvent.

  The above inert hydrocarbon medium is not particularly limited, and specific examples thereof include aliphatic hydrocarbons such as propane, butane, isobutane, pentane, isopentane, hexane, heptane, octane, decane, dodecane and kerosene; Alicyclic hydrocarbons such as cyclohexane and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as ethyl chloride, chlorobenzene and dichloromethane; and mixtures thereof.

  As described above, the strength of stirring the catalyst in the catalyst storage reactor is important as a method of controlling the isothermal crystallization time in the above range. Specifically, it is achieved by vigorously stirring in a catalyst storage reactor diluted with an inert hydrocarbon. More specifically, four or more, more preferably six or more, still more preferably eight or more stirring blades are used in the reactor (for example, an autoclave of 8 L), and the rotational speed of the stirring blades is 60 rpm or more. More preferably, the rotation speed is 90 rpm, more preferably 120 rpm or more, and a mixer may be provided in the liquid transfer route.

  The polymerization temperature in the production method for obtaining the ultrahigh molecular weight ethylene polymer powder in the above range is usually preferably 20 ° C. or more and 100 ° C. or less, more preferably 30 ° C. or more and 95 ° C. or less, and further preferably 40 ° C. or more and 90 ° C. or less preferable. Industrially efficient production is possible because the polymerization temperature is 20 ° C. or higher. On the other hand, when the polymerization temperature is 100 ° C. or less, stable operation is possible continuously.

  Usually, normal pressure or more and 15 MPa or less are preferable, 0.15 MPa or more and 14 MPa or less are more preferable, and 0.2 MPa or more and 13 MPa or less are more preferable. . When the polymerization pressure is normal pressure or higher, there is a tendency to obtain an ultrahigh molecular weight ethylene-based polymer powder having a high total metal content and a high total chlorine content, and by having a polymerization pressure of 15 MPa or less, the total metal content and total chlorine There is a tendency to be able to stably produce a low amount of ultrahigh molecular weight ethylene polymer powder.

  It is also possible to carry out the polymerization in two or more stages with different reaction conditions. Furthermore, as described, for example, in DE-A 3 127 133, the molecular weight of the resulting ultra-high molecular weight ethylene-based polymer powder causes hydrogen to be present in the polymerization system or changes the polymerization temperature. It can also be adjusted by By adding hydrogen as a chain transfer agent into the polymerization system, it is possible to control the molecular weight in an appropriate range. When hydrogen is added to the polymerization system, the molar fraction of hydrogen is preferably 0.01 mol% to 30 mol%, more preferably 0.01 mol% to 25 mol%, and still more preferably 0.01 mol% to 20 mol%. preferable. In addition, in this embodiment, other well-known components useful for manufacture of ultra-high molecular weight ethylene polymer powder other than each above components can be included.

  Generally, when polymerizing ultra-high molecular weight ethylene polymer powder, in order to suppress electrostatic adhesion of the polymer to the polymerization reactor, antistatic agent such as Stadis 450 manufactured by The Associated Octel Company It is also possible to use The Stadis 450 can also be added to the polymerization reactor by a pump or the like that is diluted in an inert hydrocarbon medium. The amount added is preferably 0.1 ppm to 50 ppm, and more preferably 20 ppm to 50 ppm, based on the amount of the ultrahigh molecular weight ethylene polymer powder produced per unit time.

  As a drying method after polymerization for obtaining the ultrahigh molecular weight ethylene-based polymer powder in the above range, a drying method which does not apply heat as much as possible is preferable. As a type of dryer, a rotary kiln system, a paddle system, a fluid dryer and the like are preferable. The drying temperature is preferably 50 ° C. or more and 150 ° C. or less, and more preferably 70 ° C. or more and 100 ° C. or less. It is also effective to introduce an inert gas such as nitrogen into the dryer to accelerate drying.

[Other ingredients]
The ultra-high molecular weight ethylene polymer powder as described above may be used in combination with various known additives, if necessary. The heat stabilizer is not particularly limited, and for example, a heat-resistant stabilizer such as tetrakis [methylene (3,5-di-t-butyl-4-hydroxy) hydrocinnamate] methane, distearylthiodipropionate, etc .; Weathering stabilizers such as bis (2,2 ', 6,6'-tetramethyl-4-piperidine) sebacate, 2- (2-hydroxy-t-butyl-5-methylphenyl) -5-chlorobenzotriazole, etc. It can be mentioned. In addition, stearic acid salts such as calcium stearate, magnesium stearate and zinc stearate which are known as lubricants and hydrogen chloride absorbents can also be mentioned as suitable additives.

[Molded body of ultra-high molecular weight ethylene polymer powder]
The molded body of the present embodiment is a molded body using the above-mentioned ultra-high molecular weight ethylene-based polymer powder. The molded body contains the above-mentioned ultra-high molecular weight ethylene-based polymer powder, and may further contain an organic peroxide as required.

[Molding method of ultra-high molecular weight ethylene polymer powder]
As a molding method of the ultra-high molecular weight polyethylene, for example, compression molding (press molding) and extrusion molding can be mentioned, though it is not limited. Compression molding is a method in which the raw material powder is uniformly dispersed in a mold, heated and pressed for molding, and then cooled and taken out. It is also possible to make a plate as a product as it is, to make a block, and finish it into a final product by cutting and the like. On the other hand, in extrusion molding, wet extrusion molding (that is, kneading extrusion molding carried out at high temperature in a state dissolved in a solvent in an extruder), fiber molding, and a ram extruder that extrudes the piston back and forth is used Be By changing the shape of the outlet of the extruder, moldings of various shapes such as sheet, flat plate, profile, pipe and the like can be obtained.

[Use of molded body]
The ultrahigh molecular weight ethylene-based polymer powder obtained as described above can have high processability and high continuous process productivity, and can be processed by various processing methods. Moreover, the molded object using ultra-high molecular weight ethylene polymer powder can be applied to various uses. Although not particularly limited, for example, separator films for secondary batteries such as lithium ion secondary batteries and lead storage batteries as main applications, fibers, non-adhesiveness, lining materials such as hoppers and chutes with low friction coefficient It is also suitably used for bearings, gears, roller guide rails, bone substitutes, bone conductive materials or bone inducers, etc. which are required to have self-lubricity, low friction coefficient and wear resistance.

  Hereinafter, the present invention will be described in more detail by way of examples and comparative examples, but the present invention is not limited at all by the following examples.

[Measurement method and conditions]
(1) Viscosity average molecular weight (Mv)
The viscosity average molecular weight of the ultrahigh molecular weight ethylene polymer powder was determined by the method described below according to ISO 1628-3 (2010). First, 20 mg of ultrahigh molecular weight ethylene polymer powder was weighed in a melting tube, and the melting tube was replaced with nitrogen, and then 20 mL of decahydronaphthalene (1,6-di-t-butyl-4-methylphenol was added at 1 g / L The mixture was stirred at 150 ° C. for 2 hours to dissolve the ultrahigh molecular weight ethylene polymer powder. The drop time (ts) between the marked lines was measured using the solution and a Canon-Fenske viscometer (manufactured by Shibata Scientific Instruments Industry Co., Ltd .: product number-100) in a 135 ° C constant temperature bath. Similarly, for samples in which the ultrahigh molecular weight ethylene polymer powder was changed to 10 mg, 5 mg, and 2.5 mg, the fall time (ts) between the marked lines was similarly measured. The fall time (tb) of only decahydronaphthalene was measured without using the ultrahigh molecular weight ethylene polymer powder as a blank. The reduced viscosity (η sp / C) of the ultra-high molecular weight ethylene-based polymer powder determined according to the following formula is plotted respectively and the concentration (C) (unit: g / dL) and the reduced viscosity (η sp) of the ultra-high molecular weight ethylene-based polymer powder The linear equation of / C) was derived, and the limiting viscosity ([η]) extrapolated to a concentration of 0 was determined.
η sp / C = (ts / tb-1) /0.1 (unit: dL / g)
Next, the viscosity average molecular weight (Mv) was calculated using the value of the above-mentioned intrinsic viscosity [eta] using the following numerical formula A.
Mv = (5.34 × 10 ⁴ ) × [η] ^1.49 ··· Formula A

(2) Titanium element content Ultrahigh molecular weight ethylene-based polymer powder is pressure-decomposed using a microwave decomposition apparatus (type ETHOS TC, manufactured by Milestone General Co., Ltd.), and ICP-MS (inductively coupled plasma) by an internal standard method. The elemental concentration of titanium as a metal in the ultrahigh molecular weight ethylene-based polymer powder was measured with a mass spectrometer, model X series X7, manufactured by Thermo Fisher Scientific Co., Ltd.).

(3) Isothermal crystallization time Measurement of the isothermal crystallization time was performed using DSC (manufactured by Perkin Elmer, trade name: DSC 8000). 8 to 10 mg of ultra-high molecular weight ethylene polymer powder was inserted into an aluminum pan and placed in the DSC. Thereafter, in the measurement of the following measurement conditions, the time until reaching 126 ° C. in step A3 is measured as the starting point (0 minute) until the exothermic peak top due to crystallization is obtained, and the time isotherm Time to
Step A1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a temperature rising rate of 10 ° C./min Step A2: Hold at 180 ° C. for 30 minutes, then lower the temperature to 126 ° C. at 80 ° C./min. : Hold at 126 ° C

(4) Aluminum element content Ultrahigh molecular weight ethylene-based polymer powder is pressure-decomposed using a microwave decomposition apparatus (type ETHOS TC, manufactured by Milestone General Co., Ltd.), and ICP-MS (inductively coupled plasma) by an internal standard method. The elemental concentration of aluminum as a metal in the ultrahigh molecular weight ethylene-based polymer powder was measured with a mass spectrometer, model X series X7, manufactured by Thermo Fisher Scientific Co., Ltd.).

(5) Heat of fusion (ΔH2)
The measurement of the heat of fusion (ΔH2) was performed using a DSC (manufactured by Perkin Elmer, trade name: DSC 8000). 8 to 10 mg of ultra-high molecular weight ethylene polymer powder was inserted into an aluminum pan and placed in the DSC. Thereafter, the heat of fusion (ΔH2) in the temperature raising process of step B3 was calculated under the following measurement conditions.
Step B1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a heating rate of 10 ° C./min Step B2: Hold at 180 ° C. for 5 minutes, then lower the temperature to 50 ° C. at 10 ° C./min : After holding for 5 minutes at 50 ° C, the temperature is raised to 180 ° C at a heating rate of 10 ° C / min.

(6) Bulk Density The bulk density of the ultrahigh molecular weight ethylene polymer powder was measured according to JIS K-6721: 1997.

(7) Tap Density The tap density of the ultrahigh molecular weight ethylene polymer powder was measured by the method described in JIS K-7370: 2000. In addition, the ratio of tap density to bulk density was calculated from the measurement results of (6) and (7).

(8) Average particle size The average particle size of the ultrahigh molecular weight ethylene polymer powder is 10 kinds of sieves defined by JIS Z8801 (mesh size: 710 μm, 500 μm, 425 μm, 355 μm, 300 μm, 212 μm, 150 μm, 106 μm, 75 μm , 53 μm), and the weight of the particles remaining on each sieve obtained when classifying 100 g of ultrahigh molecular weight ethylene polymer powder is 50% weight in the integral curve integrated from the side with the larger opening The particle size was taken as the average particle size.

(9) Content of α-Olefin Unit The measurement of the content (mol%) of the polymer unit derived from α-olefin in the ultrahigh molecular weight ethylene copolymer powder is described in G. J. Ray et al. Macromolecules, carried out according to the method disclosed in 10,773 ^(1977), using the signal of the methylene carbon to be observed by the 13 C-NMR spectrum was calculated from the integrated intensity.

Measuring device: NEC Electronics ECS-400
Observation nucleus: ¹³ C
Observation frequency: 100.53 MHz
Pulse width: 45 ° (7.5 μsec)
Pulse program: single pulse dec
PD: 5 sec
Measurement temperature: 130 ° C
Accumulated number of times: 30,000 times or more Standard: PE (-eee-) signal, 29.9 ppm
Solvent: ortho-dichlorobenzene-d4
Sample concentration: 5 to 10 wt%
Melting temperature: 130 to 140 ° C

(10) Molding method (10-1) microporous film molding 1 kg of ultrahigh molecular weight ethylene polymer powder and pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxy] as an antioxidant A mixture of polymers and the like was obtained by charging 12 g (0.3% by mass) of (phenyl) propionate] and dry blending using a tumbler blender. Furthermore, 10 kg of liquid paraffin (kinetic viscosity of 7.59 × 10 ⁻⁵ m ² / s at 37.78 ° C.) (polyethylene concentration of 10% by mass) was added to the mixture and introduced into a pre-mixing tank purged with nitrogen. The slurry was obtained by stirring at room temperature.

  After the slurry was replaced with nitrogen, it was supplied to a twin-screw extruder under a nitrogen atmosphere by a plunger pump to carry out melt kneading. Melt-kneading conditions were a set temperature of 200 ° C., a screw rotation speed of 240 rpm, and a discharge amount of 12 kg / hr.

  Subsequently, the melt-kneaded product is extruded and cast on a cooling roll controlled to a surface temperature of 25 ° C. through a T-die to obtain a gel sheet, and it is further cooled once in a room temperature atmosphere continuously. It was introduced into an axial tenter stretching machine and biaxial stretching was performed. The set stretching conditions were an MD magnification of 7.0 times, a TD magnification of 7.0 times (that is, 7 × 7 times), and a biaxial stretching temperature of 125 ° C.

  Next, it was introduced into a methyl ethyl ketone tank, and was sufficiently immersed in methyl ethyl ketone to extract and remove liquid paraffin, and then the methyl ethyl ketone was dried and removed to obtain a microporous membrane molded article. In this microporous film molded product, the chuck portion in biaxial stretching is cut with a constant width.

  In the process of obtaining a gel sheet from the melt-kneaded product described above and introducing it to a simultaneous biaxial tenter stretching machine, the process is carried out under conditions that allow the gel sheet to be stably obtained continuously for 10 minutes or more. The time from the time of cooling roller contact to the time of reaching the simultaneous biaxial tenter drawing machine was defined as "the cooling process time at the time of microporous membrane molding".

(10-2) Molding of fiber To 1 kg of ultra-high molecular weight ethylene polymer powder, 3 g of pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] was added as an antioxidant. 0.3 mass%) was added, and dry blending was performed using a tumbler blender to obtain a mixture of polymers and the like. The obtained mixture of polymers, etc. and 10 kg of liquid paraffin (kinetic viscosity of 7.59 × 10 ⁻⁵ m ² / s at 37.78 ° C.) (polyethylene concentration of 10% by mass) are introduced into the pre-mixing tank substituted with nitrogen The slurry was obtained by stirring at room temperature.

  After the slurry was replaced with nitrogen, it was supplied by a plunger pump to a twin-screw extruder under a nitrogen atmosphere to melt and knead. Melt-kneading conditions were a set temperature of 250 ° C., a screw rotation number of 200 rpm, and a discharge amount of 12 kg / hr. Thereafter, the gel spinning was processed through a spinning die.

  The gel spinning thus obtained is continuously cooled once in a room temperature atmosphere, and then introduced into a methyl ethyl ketone tank, sufficiently immersed in methyl ethyl ketone to extract and remove liquid paraffin, and then the methyl ethyl ketone is dried and removed first at 120 ° C. At 150 ° C. in two steps. The draw ratio was maximized at each stage of drawing gel spinning and xerogel spinning, and the total draw ratio was 500 times.

  In the process of obtaining gel spinning from the above slurry and introducing it into a methyl ethyl ketone tank, the process is carried out under conditions that allow gel spinning to be stably obtained continuously for 10 minutes or longer, and at that time, when passing through the die outlet The time from the time it takes to reach the methyl ethyl ketone tank was defined as the "cooling process time at the time of fiber molding".

(10-3) Compression molding (press molding)
The ultra high molecular weight ethylene polymer powder is compression molded according to JIS K 7139 (setting heating temperature: 200 ° C., heating time: 20 minutes, molding pressure: 10 MPa, mold size: 200 mm square, 5 mm thickness) A molded body was obtained through a cooling process in which heating was stopped while maintaining pressure. In the above-mentioned cooling process, the time from when heating is stopped until the temperature of the center of the molded body reaches 40 ° C. is defined as “the cooling process time at the time of compression molding”.

(10-4) Ram Extrusion Molding of ultrahigh molecular weight ethylene polymer powder was carried out by ram extrusion (inside cylinder temperature: about 240 ° C., in a horizontal ram extruder with a ram length of about 1.2 m under a pressure of about 12 MPa) The die temperature was set to about 200 ° C.), and after leaving the die, it was cooled as it was at room temperature to obtain a cylindrical molded body having a diameter of 100 mm.

  In the above-mentioned cooling step, the process is carried out under the condition that a molded body can be stably obtained continuously for 10 minutes or more, and at that time, the temperature of the surface of the molded body becomes 50 ° C. after passing through the die. The time until it was defined as "the cooling process time at the time of ram extrusion molding".

(11) Swelled state in solvent In (10-1) and (10-2), the state of the obtained slurry was visually observed. The judgment criteria for the swelling state are as follows.
○ ··· in the slurry, aggregates of between powder (lumps) is not nearly confirmed.
・ ・ ・ ························································································· · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · In the slurry, it is possible to confirm some aggregation (powder) of powders.
In × ··· in the slurry, aggregates of between powder (lumps) a lot can be confirmed.

(12) Average pore diameter of microporous membrane and uniformity of pore diameter (12-1), the average pore diameter of the obtained microporous membrane molded article was observed by SEM. The average pore diameter was determined, and the uniformity of the pore diameter was evaluated based on the following judgment criteria.
○ · · · pore diameter is almost uniform · · · holes larger or smaller than the average pore diameter are slightly noticeable × · · can not be said that the pore diameter is uniform

(13) Abrasion resistance test The abrasion resistance test (sand slurry test) was performed using the molded object obtained by (10-3) and (10-4). For the sand used in the test, the wear loss ratio was determined by the following formula B from the wear loss after 24 hours of the test, 24 kg of water 2 kg / water 2 L, rotation speed 1, 750 hours. Those with a wear loss ratio exceeding 5% were evaluated as unacceptable (x), and those with a wear loss ratio of 5% or less as excellent (o).
Wear loss ratio = (W1-W2) / W1 * 100 ... Formula B
W1 = original weight, W2 = weight after test

Catalyst Synthesis Example 1: Preparation of Solid Catalyst Component [A]
(1) Synthesis of (A-1) Carrier 1,000 mL of a 2 mol / L solution of hydroxytrichlorosilane in hexane was charged into an 8 L stainless steel autoclave fully purged with nitrogen and equipped with eight stirring blades, 65 ° C., Add 2,550 mL (equivalent to 2.68 mol of magnesium) of a hexane solution of the organic magnesium compound represented by the composition formula AlMg ₅ (C ₄ H ₉ ) ₁₁ (OC ₄ H ₉ ) ₂ dropwise over 4 hours while stirring at 120 rpm The reaction was continued while stirring at 65 ° C. and 120 rpm for 1 hour. After completion of the reaction, the supernatant was removed and washed four times with 1,800 mL of hexane. As a result of analyzing this solid ((A-1) carrier), magnesium contained per 1 g of solid was 8.31 mmol.

(2) Preparation of Solid Catalyst Component [A] Composition of 110 mL of a 1 mol / L titanium tetrachloride hexane solution and 1 mol / L while stirring at 10 ° C. in 1,970 mL of a hexane slurry containing 110 g of the above (A-1) A hexane solution of 110 mL of an organic magnesium compound represented by the formula AlMg ₅ (C ₄ H ₉ ) ₁₁ (OSiH) ₂ was simultaneously added over 1 hour. After the addition, the reaction was continued at 10 ° C. for 1 hour. After completion of the reaction, 1,100 mL of the supernatant was removed, and the solid catalyst component [A] was prepared by washing twice with 1,100 mL of hexane. The amount of titanium contained in 1 g of this solid catalyst component [A] was 0.75 mmol. The solid catalyst component [A] was supplied to the polymerization reactor through a liquid feeding route provided with a mixer.

Catalyst Synthesis Example 2: Preparation of Solid Catalyst Component [B]
In the step of preparing the solid catalyst component [A], in the step of adding a titanium tetrachloride hexane solution and a hexane solution of an organomagnesium compound, addition and termination of addition were repeated repeatedly for 5 hours each over 5 hours. The solid catalyst component [B] was prepared in the same manner as the solid catalyst component [A] except for the above.

(Example 1: PE1)
Hexane, ethylene, hydrogen, catalyst, Stadis 450 (manufactured by The Associated Octel Company) were continuously fed to a vessel type 300 L polymerization reactor equipped with a stirrer. The polymerization temperature was kept at 75 ° C. by jacket cooling. Hexane was supplied at 55 L / Hr. As a catalyst, a mixture of co-catalyst components triisobutylaluminum and diisobutylaluminum hydride and a solid catalyst component [A] were used. The solid catalyst component [A] was added to the polymerizer at a rate of 0.7 g / hr, and the mixture of triisobutylaluminum and diisobutylaluminum hydride was added to the polymerizer at a rate of 9 mmol / hr. The solid catalyst component [A] and a mixture of triisobutylaluminum and diisobutylaluminum hydride were added in equal amounts at a rate of 5 L / Hr. Similarly, Stadis 450 was added to have a concentration of 25 ppm with respect to the ultrahigh molecular weight ethylene copolymer. Hydrogen was continuously added so as to be 0.2 mol% with respect to the gas phase ethylene concentration. The polymerization pressure was maintained at 0.45 MPa by continuously feeding ethylene. Under these conditions, sufficient stirring was performed to make the inside of the polymerization reactor uniform. The production rate of the ultrahigh molecular weight ethylene copolymer was 10 kg / hr. The catalyst activity was 30,000 g-PE / g-solid catalyst component [A]. The polymerization slurry was continuously discharged to a flash drum with a pressure of 0.05 MPa so as to keep the level of the polymerization reactor constant, and unreacted ethylene was separated. The polymerization slurry was sent to a drying step after undergoing a solvent separation step continuously. The dryer was a drum type and had a jacket at 80 ° C. under a nitrogen stream. Stable and continuous operation was achieved without the presence of massive polymer and without clogging of the slurry withdrawal pipe. Furthermore, 1,000 ppm of calcium stearate (C60, manufactured by Dainichi Chemical Co., Ltd.) was added and uniformly mixed using a Henschel mixer, and the obtained powder was not passed through a sieve using a 425 μm sieve. Removed ones. The ultrahigh molecular weight ethylene polymer powder thus obtained is designated PE1.

  About the ultrahigh molecular weight ethylene polymer powder of Example 1, according to the method mentioned above, molecular weight, titanium element content, isothermal crystallization time, aluminum element content, heat of fusion (ΔH2), bulk density, tap density, and The results of measuring the average particle size are shown in Table 1. Further, the ultrahigh molecular weight ethylene-based polymer powder was molded according to the method described above, and the cooling step time, the swelling state to the solvent, the average pore diameter of the microporous membrane, and the uniformity of the pore diameter were evaluated. The results are shown in Table 1.

(Example 2: PE2)
The polymerization temperature was set to 67 ° C., and the same operation as in Example 1 was performed, except that hydrogen was not supplied, to obtain an ultrahigh molecular weight ethylene-based polymer powder (PE2). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE2. The results are shown in Table 1.

(Example 3: PE3)
The polymerization temperature was set to 74 ° C., and the same operation as in Example 1 was performed except that calcium stearate was not added, to obtain an ultrahigh molecular weight ethylene polymer powder (PE3). Evaluation similar to Example 1 was performed using obtained ultrahigh molecular weight ethylene polymer powder PE3. The results are shown in Table 1.

(Example 4: PE 4)
The polymerization temperature was set to 60 ° C., and the same operation as in Example 1 was performed, except that hydrogen supply and calcium stearate were not added, to obtain an ultrahigh molecular weight ethylene-based polymer powder (PE4). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE4. The results are shown in Table 1.

(Example 5: PE5)
The polymerization temperature is set to 93 ° C., hydrogen is continuously added so as to be 11.0 mol% with respect to the gas phase ethylene concentration, the polymerization pressure is maintained at 0.60 MPa by continuously feeding ethylene, and calcium stearate is added. The same operation as in Example 1 was carried out except that the reaction was not conducted, to obtain an ultrahigh molecular weight ethylene-based polymer powder (PE5). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE5. The results are shown in Table 1.

(Example 6: PE 6)
The same operation as in Example 1 was carried out except that the polymerization temperature was 60 ° C., hydrogen supply and calcium stearate were not added, and the polymerization pressure was maintained at 0.35 MPa by continuously supplying ethylene. , Ultra high molecular weight ethylene polymer powder (PE6) was obtained. The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE6. The results are shown in Table 1.

(Example 7: PE 7)
The same operation as in Example 1 is carried out except that the number of stirring blades at the time of preparation of the solid catalyst component [A] is four and the number of revolutions of the stirring blades is 60 rpm, an ultrahigh molecular weight ethylene polymer powder (PE7) is prepared Obtained. The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE7. The results are shown in Table 1.

(Example 8: PE 8)
The same operation as in Example 1 is carried out except that the number of stirring blades at the time of preparation of the solid catalyst component [A] is four and the number of revolutions of the stirring blades is 90 rpm, an ultrahigh molecular weight ethylene polymer powder (PE8) is prepared Obtained. The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE8. The results are shown in Table 1.

(Example 9: PE 9)
The same operation as in Example 1 is carried out except that the number of stirring blades at the time of preparation of the solid catalyst component [A] is six and the number of revolutions of the stirring blades is 60 rpm, an ultrahigh molecular weight ethylene polymer powder (PE9) is prepared Obtained. The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE9. The results are shown in Table 1.

(Example 10: PE 10)
The polymerization temperature was 82 ° C., hydrogen was continuously added so as to be 5.5 mol% with respect to the gas phase ethylene concentration, and the polymerization pressure was maintained at 0.45 MPa by continuously feeding ethylene, The same operation as in Example 1 was performed to obtain an ultrahigh molecular weight ethylene-based polymer powder (PE10). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE10. The results are shown in Table 1.

(Example 11: PE11)
At a polymerization temperature of 87 ° C., 1-butene as an α-olefin is continuously added together with ethylene so as to be 0.10 mol% relative to the gas phase ethylene concentration, and hydrogen is also relative to the gas phase ethylene concentration The same procedure as in Example 1 is carried out except that the polymerization pressure is continuously added to 6.5 mol% and the polymerization pressure is maintained at 0.45 MPa by continuously feeding ethylene, and ultrahigh molecular weight ethylene-based polymerization Powder (PE11) was obtained. The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE11. The results are shown in Table 1.

(Comparative example 1: PE12)
Add 1-butene as an α-olefin continuously with ethylene so as to be 0.40 mol% with respect to the gas phase ethylene concentration, make two stirring blades at the time of preparation of the solid catalyst component [A], and stir The same operation as in Example 1 was carried out except that the number of revolutions of the wing was set to 40 rpm and the mixer was not provided in the liquid feeding route and supplied to the reactor, to obtain an ultrahigh molecular weight ethylene polymer powder (PE12). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE12. The results are shown in Table 1.

(Comparative example 2: PE13)
The polymerization temperature is 69 ° C., 1-butene as an α-olefin is continuously added together with ethylene so as to be 0.50 mol% relative to the gas phase ethylene concentration, the polymerization pressure is 0.20 MPa, and a solid catalyst The same operation as in Example 2 is performed except that the number of stirring blades at the time of preparation of component [A] is two, the number of rotations of the stirring blades is 40 rpm, and the mixer is not provided in the liquid feeding route. An ultrahigh molecular weight ethylene polymer powder (PE13) was obtained. Evaluation similar to Example 1 was performed using obtained ultrahigh molecular weight ethylene polymer powder PE13. The results are shown in Table 1.

(Comparative example 3: PE14)
The polymerization temperature is 70 ° C., hydrogen is continuously added so as to be 0.10 mol% with respect to the gas phase ethylene concentration, the number of stirring blades at the time of preparation of the solid catalyst component [A] is four, The same operation as in Example 1 was performed except that the number of revolutions was 50 rpm, to obtain an ultrahigh molecular weight ethylene-based polymer powder (PE14). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE14. The results are shown in Table 1.

(Comparative example 4: PE15)
The same operation as in Example 5 is carried out except that the polymerization temperature is 94 ° C. and hydrogen is continuously added so as to be 11.5 mol% relative to the gas phase ethylene concentration, and an ultrahigh molecular weight ethylene polymer powder Obtained (PE15). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene-based polymer powder PE15. The results are shown in Table 1.

(Comparative example 5: PE16)
The same operation as in Example 6 was carried out except that the polymerization temperature was 56 ° C. and the polymerization pressure was 0.30 MPa, to obtain an ultrahigh molecular weight ethylene-based polymer powder (PE16). Evaluation similar to Example 1 was performed using obtained ultrahigh molecular weight ethylene polymer powder PE16. The results are shown in Table 1.

(Comparative example 6: PE17)
The experiment was conducted except that the polymerization temperature was 72 ° C., hydrogen was continuously added so as to be 0.10 mol% with respect to the gas phase ethylene concentration, the polymerization pressure was 0.15 MPa, and calcium stearate was not added. The same operation as in Example 1 was performed to obtain an ultrahigh molecular weight ethylene-based polymer powder (PE17). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE17. The results are shown in Table 1.

(Comparative example 7: PE18)
The same operation as in Example 1 was carried out except using the solid catalyst component [B] instead of the solid catalyst component [A], to obtain an ultrahigh molecular weight ethylene-based polymer powder (PE18). The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE18. The results are shown in Table 1.

(Comparative example 8: PE19)
Stadis 450, no addition of hydrogen, polymerization temperature of 70 ° C., hexane supply rate of 80 L / Hr, addition of solid catalyst component at 0.7 g / Hr, diisobutylaluminum hydride Then, the same operation as Comparative Example 7 is performed except that triisobutylaluminum is added to the polymerizer at 10 mmol / hr, the polymerization pressure is 0.2 MPa, and the jacket temperature of the dryer is 85 ° C. An ultrahigh molecular weight ethylene polymer powder (PE19) was obtained. The same evaluation as in Example 1 was performed using the obtained ultrahigh molecular weight ethylene polymer powder PE19. The results are shown in Table 1.

  From the above, the ultra-high molecular weight ethylene polymer powder of the present invention not only shortens the cooling step time in the production of separator films for secondary batteries, fibers, compression molded products, ram extruded products, but also at the time of wet extrusion It is found that the swelling failure of the ultra-high molecular weight ethylene polymer powder in the solvent is difficult to occur, and the average pore diameter of the secondary battery separator membrane can be reduced and made uniform. .

  Also, even if molded articles using these ultrahigh molecular weight ethylene polymer powders are excellent in the above-mentioned physical properties, separator films for secondary batteries such as lithium ion secondary batteries and lead storage batteries, fibers, non-adhesive Bearings, gears, roller guide rails, bone substitutes, bone conductive materials or bone guides that require high rigidity, low coefficient of friction and lining materials such as hoppers and chutes, and also self lubricity and low coefficient of friction and wear resistance It is suitably used for materials and the like.

  The ultra-high molecular weight ethylene polymer powder of the present invention not only shortens the cooling step time in the production of separator membranes for secondary batteries, fibers, compression molded products, ram extruded products, but also super It is excellent in that swelling defects of high molecular weight ethylene-based polymer powder are unlikely to occur, and the average pore diameter of the secondary battery separator membrane can be reduced and made uniform. Have industrial applicability.

That is, the present invention is as follows.
[1]
And ethylene units and / or ethylene units and α-olefin units having 3 to 8 carbon atoms as constituent units,
The viscosity-average molecular weight is 10,000,000 or less 1 5 0,000 or more,
The elemental titanium content by inductively coupled plasma mass spectrometry (ICP / MS) is 20 ppm or less,
In the measurement of the following isothermal crystallization time measurement conditions using a differential scanning calorimeter, the time when the temperature reached 126 ° C. in step A3 is taken as the starting point (0 minute), and the time when the exothermic peak top due to crystallization is obtained Said isothermal crystallization time is less than 6 minutes when said is an isothermal crystallization time,
Ultra high molecular weight ethylene polymer powder.
(Isothermal crystallization time measurement conditions)
Step A1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a temperature rising rate of 10 ° C./min Step A2: Hold at 180 ° C. for 30 minutes, then lower the temperature to 126 ° C. at 80 ° C./min. : Hold at 126 ° C [2]
The ultrahigh molecular weight ethylene polymer powder according to the above [1], wherein the content of titanium element by ICP / MS is 15 ppm or less.
[3]
The ultrahigh molecular weight ethylene polymer powder according to the above [1], wherein the titanium element content by ICP / MS is 7 ppm or less.
[4]
The ultrahigh molecular weight ethylene polymer powder according to any one of the above [1] to [3], wherein the aluminum element content by ICP / MS is 10 ppm or less.
[5]
In the measurement of the following heat of fusion (ΔH2) measurement conditions using a differential scanning calorimeter, the heat of fusion (ΔH2) in the temperature rising process of step B3 is 250 J / g or less according to the above [1] to [4] The ultra-high molecular weight ethylene-based polymer powder according to any of the above.
(The heat of fusion (ΔH2) measurement condition)
Step B1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a heating rate of 10 ° C./min Step B2: Hold at 180 ° C. for 5 minutes, then lower the temperature to 50 ° C. at 10 ° C./min : After holding for 5 minutes at 50 ° C, the temperature is raised to 180 ° C at a temperature rising rate of 10 ° C / min [6]
The tap density is 0.35 g / cm ³ or more and 0.70 g / cm ³ or less, and the bulk density is 0.40 g / cm ³ or more and 0.60 g / cm ³ or less. The ultra-high molecular weight ethylene-based polymer powder according to any one of 5).
[7]
The ultrahigh molecular weight ethylene polymer powder according to the above [6], wherein the ratio of tap density to bulk density is 1.10 or more and 1.50 or less.
[8]
The ultrahigh molecular weight ethylene polymer powder according to any one of the above [1] to [7], which has an average particle size of 50 μm to 200 μm.
[9]
The molded object using the ultra-high molecular weight ethylene polymer powder in any one of said [1]-[8].
[10]
The molded object according to the above [9], which is a separator film or fiber for a secondary battery obtained by a wet extrusion method.
[11]
The molded object of the said [10] description whose secondary battery is a lithium ion secondary battery or lead acid battery.
[12]
The molded article according to the above [10], wherein the product using fiber is a rope, a net, a bulletproof clothing, a protective clothing, a protective glove, a fiber reinforced concrete product or a helmet.
[13]
The molded article according to the above [9], which is used for lining applications, bearings, gears, roller guide rails, bone substitutes, bone conductive materials, or bone inducers.

Claims (13)

And ethylene units and / or ethylene units and α-olefin units having 3 to 8 carbon atoms as constituent units,
Viscosity average molecular weight is 100,000 or more and 10,000,000 or less,
The elemental titanium content by inductively coupled plasma mass spectrometry (ICP / MS) is 20 ppm or less,
In the measurement of the following isothermal crystallization time measurement conditions using a differential scanning calorimeter, the time when the temperature reached 126 ° C. in step A3 is taken as the starting point (0 minute), and the time when the exothermic peak top due to crystallization is obtained Said isothermal crystallization time is less than 6 minutes when said is an isothermal crystallization time,
Ultra high molecular weight ethylene polymer powder.
(Isothermal crystallization time measurement conditions)
Step A1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a temperature rising rate of 10 ° C./min Step A2: Hold at 180 ° C. for 30 minutes, then lower the temperature to 126 ° C. at 80 ° C./min. : Hold at 126 ° C   The ultrahigh molecular weight ethylene polymer powder according to claim 1, wherein the titanium element content by ICP / MS is 15 ppm or less.   The ultrahigh molecular weight ethylene polymer powder according to claim 1, wherein the titanium element content by ICP / MS is 7 ppm or less.   The ultrahigh molecular weight ethylene polymer powder according to any one of claims 1 to 3, wherein an aluminum element content by ICP / MS is 10 ppm or less. The method according to any one of claims 1 to 4, wherein in the measurement of the following heat of fusion (ΔH2) measurement conditions using a differential scanning calorimeter, the heat of fusion (ΔH2) in the temperature rising process of step B3 is 250 J / g or less. Ultrahigh molecular weight ethylene-based polymer powder as described.
(The heat of fusion (ΔH2) measurement condition)
Step B1: Hold at 50 ° C. for 1 minute, then raise the temperature to 180 ° C. at a heating rate of 10 ° C./min Step B2: Hold at 180 ° C. for 5 minutes, then lower the temperature to 50 ° C. at 10 ° C./min : After holding for 5 minutes at 50 ° C, the temperature is raised to 180 ° C at a heating rate of 10 ° C / min The tap density is 0.35 g / cm ³ or more and 0.70 g / cm ³ or less, and the bulk density is 0.40 g / cm ³ or more and 0.60 g / cm ³ or less. The ultra-high molecular weight ethylene-based polymer powder according to any of the above.   7. The ultrahigh molecular weight ethylene polymer powder according to claim 6, wherein the ratio of tap density to bulk density is 1.10 or more and 1.50 or less.   The ultrahigh molecular weight ethylene polymer powder according to any one of claims 1 to 7, which has an average particle size of 50 μm to 200 μm.   A molded article using the ultrahigh molecular weight ethylene-based polymer powder according to any one of claims 1 to 8.   The molded body according to claim 9, which is a separator membrane or fiber for a secondary battery obtained by a wet extrusion method.   The molded article according to claim 10, wherein the secondary battery is a lithium ion secondary battery or a lead storage battery.   The molded article according to claim 11, wherein the product using fiber is a rope, a net, a bulletproof clothing, a protective clothing, a protective glove, a fiber reinforced concrete product or a helmet. 10. A shaped body according to claim 9, used for lining applications, bearings, gears, roller guide rails, bone substitutes, bone conductive materials or bone inducers.