JP6843660B2 - Ethylene polymer powder and its molded product - Google Patents

Description

The present invention relates to an ethylene polymer powder and a molded product thereof.

High molecular weight ethylene-based polymers are used in a wide variety of applications such as films, sheets, microporous membranes, fibers, and pipes. In particular, high molecular weight ethylene polymer powder is used as a raw material for a microporous film for a separator of a secondary battery represented by a lead storage battery and a lithium ion battery and a high-strength fiber. The reason why the high molecular weight ethylene polymer powder is used is that it has a high molecular weight, so that it has excellent stretchability, high strength, high chemical stability, and excellent long-term reliability.

Since these high molecular weight ethylene polymer powders have a high molecular weight, they are difficult to process by injection molding or the like. Therefore, in addition to press molding and extrusion molding, they are often dissolved in a solvent for molding. In the industrial world, especially in the lithium ion secondary battery separator and high-strength fiber industries, there is a strong demand for cost reduction along with high demand growth, and high productivity is strongly desired. Further, particularly for lithium ion secondary battery separators and high-strength fibers, high product dimensional stability such as film thickness and fiber diameter is strongly desired from the viewpoint of long-term reliability.

In recent years, high molecular weight ethylene polymer powder has been developed as a raw material for lithium ion secondary battery separators and high-strength fibers using the powder (see, for example, Patent Documents 1 to 4).

Japanese Unexamined Patent Publication No. 2015-21273 International Publication No. 2004/081064 International Publication No. 2015/005287 Japanese Unexamined Patent Publication No. 2014-040577

As described above, the ultra-high molecular weight ethylene polymer powder (hereinafter, also referred to as “ethylene polymer powder”) used for microporous films and high-strength fibers has no unmelted material and is manufactured in the manufacturing process. In the use of high-strength fibers that can include a drawing step, it is desired that the fibers after drawing are uniform fibers with less yarn breakage and fluffing. On the other hand, it is common to add a chlorine catcher agent such as calcium stearate to the ethylene polymer powder. However, in applications such as microporous membranes and high-strength fibers, calcium stearate may be concentrated in a solvent that is recovered and recycled after the polymer is dissolved, and the presence of concentrated calcium stearate in the molded product is a drawback (for example, fine). Since relatively large holes in the porous film and thread breakage of high-strength fibers may occur), it is required not to add a chlorine catcher agent such as calcium stearate. However, ethylene-based polymer powder produced using a conventional Ziegler-Natta type catalyst contains titanium-chlorine in the solid catalyst, so if a chlorine catcher agent is not added, a high-strength fiber molding machine or drawing roll There is a problem that rust is generated due to such factors, and the production processing machine is stopped by cleaning the roll or the like, so that continuous processing cannot be performed and the productivity is inferior.

Further, it is known that when a large amount of titanium-chlorine remains in a molded product, a tone change from white to yellow occurs immediately after molding or after molding, and it is also required to suppress the color tone change after processing.

The present invention has been made in view of the above problems, and is capable of providing a chlorine catcher agent such as calcium stearate, which has sufficiently little unmelted material at the time of melting, thread breakage and fluffing at the time of drawing, and high strength after drawing. Using ethylene-based polymer powder, which is highly productive, enables long-term continuous stable operation in a production processing machine, and can suppress color change of molded products, and such ethylene-based polymer powder. An object of the present invention is to provide a obtained molded product.

Therefore, as a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a predetermined ultra-high molecular weight ethylene-based polymer powder can solve the above-mentioned problems, and have completed the present invention. I arrived.
That is, the present invention is as follows.
[1]
1) The viscosity average molecular weight is 200,000 or more,
2) The sulfur content is in the range of 0.10 or more and 50 ppm or less.
3) The chlorine content / sulfur content ratio is in the range of 0.010 or more and 10 or less.
An ethylene-based polymer powder,
An ethylene polymer powder having a chlorine content of 10 ppm or less in the ethylene polymer powder .
[2]
Either the ethylene homopolymer (A); or the ethylene copolymer (B).
The ethylene copolymer (B) is
a) Ethylene 75.0% by weight or more and less than 100% by mass,
b) α-olefin having 3 to 20 carbon atoms, cyclic olefin having 3 to 20 carbon atoms, formula CH ₂ =
At least one selected from the group consisting of a compound represented by CHR (where R is an aryl group having 6 to 20 carbon atoms) and a linear, branched or cyclic diene having 4 to 20 carbon atoms. Comonomer, which is a seed olefin, is more than 0% by mass and 25.0% by mass or less.
The ethylene-based polymer powder according to the above [1], which is obtained by copolymerizing the above.
[3]
A molded product obtained by using the ethylene-based polymer powder according to the above [1] or [2].
[4]
A separator for a lithium ion secondary battery obtained by using the ethylene-based polymer powder according to the above [1] or [2].
[5]
A fiber obtained by using the ethylene-based polymer powder according to the above [1] or [2].
[6]
A press-molded product obtained by using the ethylene-based polymer powder according to the above [1] or [2].

According to the present invention, unmelted matter at the time of melting, thread breakage and fluffing at the time of drawing processing are sufficiently small, strength after drawing is high, and production is possible with high productivity without using a chlorine catcher agent such as calcium stearate. It is possible to provide an ethylene-based polymer powder capable of long-term continuous stable operation in a processing machine and capable of suppressing a change in color tone of a molded product, and a molded product obtained by using such an ethylene-based polymer powder. ..

Hereinafter, embodiments for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail, but the present invention is not limited thereto. Various modifications are possible within the range that does not deviate from the gist.

[Ethylene polymer powder]
The ethylene polymer powder according to this embodiment satisfies the following 1) to 3).
1) The viscosity average molecular weight is 200,000 or more;
2) The sulfur content in the polymer is in the range of 0.10 to 50 ppm;
3) The chlorine content / sulfur content ratio in the polymer is in the range of 0.010-10;
By having the above structure, the ethylene-based polymer powder according to the present embodiment has no unmelted matter at the time of molding, has excellent strength of the obtained molded product, has less yarn breakage and fluff during molding, and causes product loss. Few. Furthermore, since the amount of chlorine in the ethylene-based polymer powder is small, rust (metal corrosion) of the molding machine / processing machine can be suppressed, and the molding machine / processing machine does not have to be stopped, so that long-term continuous operation can be performed. Specifically, molded products such as gel-spun fibers and processed products such as lithium-ion battery separators can be continuously and stably produced. Further, since the amount of chlorine is small, the discoloration of the molded product is small, and the quality of the product is sufficiently changed.

[Viscosity average molecular weight (Mv)]
The viscosity average molecular weight (Mv) is 200,000 or more. The viscosity average molecular weight (Mv) is preferably 200,000 or more and 150,000 or less, and more preferably 250,000 or more and 10,000,000 or less. When the viscosity average molecular weight is 200,000 or more, the ethylene-based polymer powder of the present embodiment has an ultra-high molecular weight, and the strength of the molded product is improved. Further, when the viscosity average molecular weight is 15,000,000 or less, the stretchability is improved. Further, when the viscosity average molecular weight is in the above range, the productivity is excellent, and when molded, the stretchability and the film strength are excellent. Ethylene-based polymer powder having such characteristics can be suitably used for, for example, a lithium ion secondary battery separator and high-strength fibers.

As a method of controlling the viscosity average molecular weight within the above range, it is possible to change the polymerization temperature of the reactor when polymerizing the ethylene-based polymer powder. In general, the higher the polymerization temperature, the lower the viscosity average molecular weight tends to be, and the lower the polymerization temperature, the higher the viscosity average molecular weight tends to be.

Further, a chain transfer agent may be added when polymerizing the ethylene polymer powder. By adding a chain transfer agent, the viscosity average molecular weight of the ethylene-based polymer powder produced even at the same polymerization temperature can be controlled to be low.

Further, the chain transfer agent (for example, hydrogen) in the polymerization reactor when producing the ethylene polymer powder is reduced as much as possible, or a compound having a hydrogenation ability (hydrogenation catalyst) is used for removing the chain transfer agent. There are methods such as. In particular, when polymerization is carried out using a metallocene catalyst, the initial polymerization activity is high, so that when introduced into a polymerization reactor, massive scale is likely to be generated due to poor dispersion of the catalyst or the like. In order to suppress this, Japanese Patent Application Laid-Open No. 2000-198804 proposes that the catalyst and hydrogen are mixed in advance before entering the polymerization reactor, but when the ethylene-based polymer powder is polymerized, it is proposed. In the above, the introduced hydrogen acts as a chain transfer agent in the polymerization system and suppresses the increase in the molecular weight of the ethylene-based polymer powder. In order to polymerize the ethylene-based polymer powder stably and efficiently, it is necessary to add a compound having a hydrogenating ability by using this hydrogen as a chain transfer agent remover. That is, by hydrogenating ethylene with a compound having a hydrogenating ability, it is possible to remove hydrogen consumed by ethane and in the polymerization system (see, for example, International Publication No. 2004/081064).

The viscosity average molecular weight (Mv) of the ethylene polymer powder according to the present embodiment is obtained by dissolving the ethylene polymer powder in a decahydronaphthalene solution at different concentrations and extrapolating the reduced viscosity obtained at 135 ° C. to a concentration of 0. It can be calculated by the following formula A from the ultimate viscosity [η] (dL / g) obtained. More specifically, it can be obtained by the method described in Examples.
Mv = (5.34 × 10 ⁴ ) × [η] ^1.49・ ・ ・ Formula A

[Sulfur content]
The sulfur content of the ethylene polymer powder of the present embodiment is preferably 0.10 ppm or more and 50 ppm or less, more preferably 0.10 ppm or more and 40 ppm or less, and preferably 0.10 ppm or more and 30 ppm or less. More preferred.

In the present embodiment, although the reason is not clear, the presence of this sulfur component in the polymer has the effect of suppressing rust in the molded product processing machine and suppressing the color tone change of the molded product, and the unmelted product in the molded product. It has been found that it has an effect of suppressing an abnormal polymer or the like which adheres to a stagnation portion in a polymerization reactor and grows by polymerization, which may cause thread breakage or fluffing. In order to exert this effect more sufficiently, the sulfur component should be present in the polymer and its content should be in the range of 0.10 ppm or more, and the sulfur content should be 50 ppm or less. Therefore, it was found that it is possible to suppress the decrease in catalytic activity and the change in color tone.

The sulfur component in the ethylene-based polymer powder is not particularly limited, but for example, a sulfur compound containing a sulfur component that can be added to the polymerization system when polymerizing the ethylene-based polymer powder is used. It can be derived, and the sulfur compound is preferably an organic sulfur compound. As the organic sulfur compound, thioether, thiophene, thiol, sulfoxide, sulfone and thioketone, sulfonic acid, sulfonic acid ester and amide compound are preferable. In particular, sulfonic acids, sulfonic acid esters and amide compounds are more preferable. As such a compound, when polymerizing an ethylene-based polymer powder, an antistatic agent such as Stadis450 manufactured by Innospec (distributor Maruwa Bussan) is used in order to suppress static electricity adhesion of the polymer to the polymerization reactor. It is also possible, and a component of a sulfur compound is present in the antistatic agent such as Stadsi450.

Regarding the sulfur content, from the viewpoint of making it easier for the sulfur component to be effectively contained in the powder obtained by polymerization, the method of adding the sulfur compound to the polymerization system together with the co-catalyst, the solid catalyst and the sulfur compound are the same. A method of adding to the polymerization system on a line or a close line, a method of adding a mixture of a sulfur compound in a solid catalyst to the polymerization system, and a method of stirring the solid catalyst and the sulfur compound in the polymerization system at a low speed to obtain an ethylene-based weight. The sulfur content in the coalescence can be controlled.

Regarding the method of adding the solid catalyst and the sulfur compound to the polymerization system in a line close to each other as a method of controlling the sulfur content, the "close line" is a line for supplying the solid catalyst and the sulfur compound to the polymerization system. The supply port is preferably, for example, a distance of 10% or less of the diameter of the polymerization reactor, and more preferably 5% or less.

Further, as another method for controlling the sulfur content of the ethylene-based polymer powder within the above range, a method for increasing the polymerization activity, that is, a polymerization catalyst, a co-catalyst, a polymerization temperature, a polymerization pressure, a slurry concentration, a residence time, etc. There is a method of controlling. It is preferable to use a metallocene-based catalyst as the polymerization catalyst.

The sulfur content of the powder and the chlorine content described later refer to the content of the sulfur atom and the chlorine atom in the powder, not the content of the compound containing the sulfur atom and the chlorine atom in the powder, respectively.

[Chlorine content]
The chlorine content of the ethylene polymer powder of the present embodiment is preferably 10 ppm or less, more preferably 8 ppm or less, and further preferably 6 ppm or less. By setting the chlorine content to 10 ppm or less, it is possible to suppress rust in the molding machine and suppress changes in the color tone of the molded product.

As a method of controlling the chlorine content of the ethylene-based polymer powder within the above range, it is controlled by a method of increasing the polymerization activity, that is, a polymerization catalyst, a co-catalyst, a polymerization temperature, a polymerization pressure, a slurry concentration, a residence time, and the like. The method can be mentioned. It is preferable to use a metallocene-based catalyst as the polymerization catalyst.

[Chlorine content / Sulfur content]
The chlorine content / sulfur content ratio of the ethylene polymer powder of the present embodiment is preferably 0.010 or more and 10 or less, more preferably 0.050 or more and 10 or less, and 0.10 or more and 10 or less. The following is more preferable. By setting the ratio of chlorine content / sulfur content in the ethylene polymer powder to the above range, the reason is not clear, but sulfur is present in a certain ratio with respect to chlorine, and chlorine derived from the catalyst in polyethylene is present. It is presumed that the change in color tone due to the above can be suppressed.

As a method of controlling the chlorine content / sulfur content ratio in the ethylene-based polymer powder, a method of adding a sulfur compound to the polymerization system together with a co-catalyst, or a method of adding a solid catalyst and a sulfur compound to the polymerization system on the same line or a similar line. The chlorine content in the ethylene-based polymer powder / by the method of adding, the method of adding a mixture of a sulfur compound in a solid catalyst to the polymerization system, and the stirring of the solid catalyst and the sulfur compound in the polymerization system at a low speed. The ratio of sulfur content can be controlled.

Further, as another method of controlling the chlorine content / sulfur content ratio of the ethylene-based polymer powder within the above range, there is a method of increasing the polymerization activity, that is, a polymerization catalyst, a co-catalyst, a polymerization temperature, a polymerization pressure, and a slurry. Examples thereof include a method of controlling by concentration, residence time and the like. It is preferable to use a metallocene-based catalyst as the polymerization catalyst.

[Concentration of ethylene-based polymer powder comonomer]
In the present specification, the naming of each monomer unit constituting the polymer follows the naming of the monomer from which the monomer unit is derived. For example, "ethylene unit" means a structural unit of a polymer produced as a result of polymerizing ethylene, which is a monomer, and its structure is a molecular structure in which two carbons of ethylene are the main chain of the polymer. is there. Further, the "comonomer unit" means a structural unit of a polymer produced as a result of polymerizing a comonomer which is a monomer, and its structure is such that two carbons of an olefin contained in the comonomer form a polymer main chain. It is a molecular structure.

The ethylene-based polymer powder used in the present embodiment is not particularly limited, and specific examples thereof include an ethylene homopolymer and a copolymer of ethylene and an olefin copolymerizable with ethylene. The olefin copolymerizable with ethylene is not particularly limited, but specifically, an α-olefin having 3 to 20 carbon atoms, a cyclic olefin having 3 to 20 carbon atoms, and the formula CH ₂ = CHR (where R is). Examples thereof include at least one olefin selected from the group consisting of a compound represented by an aryl group having 6 to 20 carbon atoms) and a diene having 4 to 20 carbon atoms. The diene is linear, branched or cyclic. Among these, as the copolymerizable olefin, propylene and 1-butene are preferable from the viewpoint of heat resistance and strength of a molded product typified by a microporous membrane or high-strength fiber. When the ethylene-based polymer powder contains a copolymerization of ethylene and olefin, the molar ratio of ethylene to the copolymer powder is preferably 75% by mass or more and less than 100% by mass, and 90% by mass or more and less than 100% by mass. More preferably, it is more preferably 5% by mass or more and less than 100% by mass. When the ethylene-based polymer powder contains a copolymerization of ethylene and olefin, the heat resistance and / or strength tends to be superior when the molar ratio of ethylene is within the above range.

As a method for controlling the b) comonomer content in the ethylene polymer powder within the above range, it is possible to change b) comonomer / [ethylene + b) comonomer] (mol%) added to the polymerization reactor. Be done. In the production of ethylene-based polymer powder using a normal Ziegler-Natta catalyst, b) the molecular weight tends to decrease due to the comonomer. It is considered that this is because b) the comonomer acts as a chain transfer agent. In order to increase the molecular weight of the ethylene polymer powder, it is preferable to reduce the content of b) comonomer as much as possible. On the other hand, in the metallocene catalyst, since the molecular weight can be controlled by adding a compound having a hydrogenation ability or the like, b) it is possible to produce a region having a high comonomer content while maintaining the high molecular weight.

In addition, b) The measurement of the content of the comonomer unit was carried out by G.M. J. Performed according to the method disclosed in Macromolecules, 10, 773 (1977) by Ray et al., B) The content of comonomer units is the area of the methylene carbon signal observed by the ^{13 C-NMR spectrum.} It can be calculated from the strength. More specifically, it can be measured by the method described in Examples.

[Manufacturing method of ethylene polymer powder]
The catalyst component used for producing the ethylene-based polymer powder according to the present embodiment is not particularly limited, and can be produced using a general Ziegler-Natta catalyst or metallocene catalyst, and a metallocene catalyst described later. It is preferably manufactured using the system. As the Ziegler-Natta catalyst and the metallocene catalyst, for example, the Ziegler-Natta catalyst and the metallocene catalyst disclosed in Japanese Patent No. 5782558 and International Publication No. 2015/005287 can be used.

When the solid catalyst component and the organometallic compound component (hereinafter abbreviated as catalyst) are added to the polymerization system under the polymerization conditions of the ethylene-based polymer powder, the catalyst component is polymerized separately. It may be added into the system, or both may be mixed in advance and then added into the polymerization system. The ratio of the two to be combined is not particularly limited, but the molar ratio of the organometallic compound component to the titanium component in the solid catalyst is preferably 1 or more and 500 or less, more preferably 10 or more and 200 or less, and further preferably 10 or more and 100 or less. .. Another purpose of mixing the two is to prevent electrostatic adhesion to storage tanks, pipes, and the like.

Examples of the polymerization method in the method for producing an ethylene-based polymer powder include a method of polymerizing ethylene by a suspension polymerization method or copolymerizing ethylene with b) a comonomer. As the polymerization method, the suspension polymerization method is preferable from the viewpoint of efficiently removing the heat of polymerization. In the suspension polymerization method, an inert hydrocarbon medium can be used as the medium, and the olefin itself can also be used as the solvent.

The inert hydrocarbon medium is not particularly limited, but specifically, aliphatic hydrocarbons such as propane, butane, isopentane, pentane, isopentane, hexane, heptane, octane, decane, dodecane, kerosene; cyclopentane, Aliphatic hydrocarbons such as cyclohexane and methylcyclopentane; and mixtures thereof and the like can be mentioned.

The polymerization temperature in the production method for obtaining the ethylene polymer powder of the present embodiment is preferably 40 ° C. or higher and 100 ° C. or lower, more preferably 50 ° C. or higher and 95 ° C. or lower, and 60 ° C. or higher and 90 ° C. The following is more preferable. When the polymerization temperature is 40 ° C. or higher, industrially efficient production is possible. When the polymerization temperature is 100 ° C. or lower, it is possible to suppress a lumpy scale in which the polymer is partially melted and clog the extraction line, and continuous and stable production is possible.

The polymerization pressure in the production method for obtaining the ethylene-based polymer powder of the present embodiment is preferably normal pressure or more and 2 MPa or less, more preferably 0.2 MPa or more and 1.5 MPa or less, and 0.3 MPa or more. It is more preferably 1.0 MPa or less. When the polymerization pressure is equal to or higher than normal pressure, an ethylene-based polymer powder having a small amount of metal components and chlorine as a catalyst residue tends to be obtained. When the polymerization pressure is 2 MPa or less, the ethylene-based polymer powder tends to be stably produced without generating massive scale due to rapid polymerization in the polymerization reactor.

Generally, when polymerizing an ethylene polymer powder, an antistatic agent such as Stadis or STATSAFE manufactured by Innospec (distributor Maruwa Bussan) should be used in order to suppress the electrostatic adhesion of the polymer to the polymerization reactor. Is also possible. As the antistatic agent such as Stadis and STATSAFE, a diluted solution in an inert hydrocarbon medium can be added to the polymerization reactor by a pump or the like. The amount added at this time is preferably 1 ppm or more and 500 ppm or less, and more preferably 10 ppm or more and 250 ppm or less, based on the amount of ethylene-based polymer powder produced per unit time.

The slurry containing the ethylene-based polymer powder of the present embodiment is quantitatively extracted from the polymerization reactor, separated from the solvent using a centrifuge or the like, and then sent to a dryer. At this time, the solvent content is preferably controlled to 20% by weight or more and 50% by weight.

As a drying method after polymerization for obtaining the ethylene-based polymer powder of the present embodiment, a drying method in which heat is not applied as much as possible is preferable. As the type of dryer, a rotary kiln method, a paddle method, a fluidized dryer, or the like is preferable. The drying temperature is preferably 50 ° C. or higher and 150 ° C. or lower, and more preferably 70 ° C. or higher and 100 ° C. or lower. It is also effective to introduce an inert gas such as nitrogen into the dryer to promote drying. At that time, it is more effective to accompany steam or the like as a deactivating agent for the solid catalyst.

The ethylene-based polymer powder of the present embodiment may be used by adding various known additives, if necessary. Examples of the additive include a heat stabilizer, a lubricant, a hydrogen chloride absorber and the like. The heat stabilizer is not particularly limited, and is, for example, a heat stabilizer such as tetrakis [methylene (3,5-di-t-butyl-4-hydroxy) hydrocinnamate] methane and distearylthiodipropionate; And weather stabilizers such as bis (2,2', 6,6'-tetramethyl-4-piperidin) sebacate, 2- (2-hydroxy-t-butyl-5-methylphenyl) -5-chlorobenzotriazole, etc. ; Etc. can be mentioned. Moreover, as the lubricant and the hydrogen chloride absorber, for example, stearate such as calcium stearate, magnesium stearate, zinc stearate and the like can be preferably mentioned.

[Molded product of ethylene polymer powder]
In the present embodiment, a molded product can be obtained by using the above ethylene-based polymer powder, and specifically, a lithium ion battery separator, fibers (high-strength fibers, etc.) and a press-molded product can be obtained. it can. By using the above ethylene polymer powder, it is possible to suppress metal corrosion around the molding machine such as a press plate, gel spinning, lithium ion battery separator, etc. when manufacturing the above molded product, and therefore it is continuously stable. The molded product produced in this manner can be obtained. Further, since the ethylene-based polymer powder contains less chlorine, a molded product with less discoloration and no change in quality as a product can be obtained.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
First, a method for evaluating the physical properties of the ethylene-based polymer powder will be described.

[Method for measuring viscosity average molecular weight (Mv) of ethylene polymer powder]
The molecular weight of the ethylene polymer powder was determined by the method shown below according to ISO1628-3 (2010).

First, 10 mg of ethylene-based polymer powder is weighed in the melting tube, the melting tube is replaced with nitrogen, and then 20 mL of decahydronaphthalene (2,6-di-t-butyl-4-methylphenol) is adjusted to 1 g / L. Was added, and the mixture was stirred at 150 ° C. for 2 hours to dissolve the ethylene-based polymer powder. Measure the fall time (ts) between marked lines using a Canon-Fenceke viscometer (manufactured by Shibata Kagaku Kikai Kogyo Co., Ltd .: product number -100) in a constant temperature bath at 135 ° C. for the solution of the ethylene polymer powder. did. Similarly, the fall time (ts) between the marked lines was measured for the sample in which the amount of the ethylene-based polymer powder was changed to 7 mg, 5 mg, and 3 mg. The fall time (tb) of decahydronaphthalene alone as a blank was measured. The reduced viscosity (ηsp / C) of the ethylene-based polymer powder obtained according to the following formula is plotted to determine the concentration (C) (unit: g / dL) and the reduced viscosity (ηsp / C) of the ethylene-based polymer powder. A linear equation was derived and extrapolated to a concentration of 0 to determine the ultimate viscosity [IV].
ηsp / C = (ts / tb-1) / C (unit: dL / g)
This limit viscosity was substituted into the following formula to determine the viscosity average molecular weight (Mv).
Mv = (5.34 × 10 ⁴ ) × [η] ^1.49

[Measurement of sulfur content of ethylene polymer powder]
100 mg of ethylene polymer powder was weighed and burned in a combustion tube, the generated gas was absorbed by pure water containing thin hydrogen peroxide, and a part of the absorption liquid was automatically injected into an ion chromatograph for measurement.
Combustion system: Combustion furnace (SQ-1 type), absorption unit (HSU-35 type)
Combustion tube: Quartz Combustion furnace temperature: Mobile furnace 400 → 900 ° C, 16 minutes Solid furnace 1,000 ° C, 4 minutes Ion chromatography system: ICA-2000 Made by Toa DK Co., Ltd. Column: Shodex IC SI-904E
(4.0mm ID * 250mm) 35 ℃
Eluent: 1.0 mMol / L Na ₂ CO ₃ 1.7 mMol / L NaHCO ₃
Flow velocity: 1.2 ml / min
Injection volume: 100 μl
Absorption liquid: A small amount of H ₂ O ₂ added pure water (25 ml + 15 ml, total 40 ml)
Detection: Electrical conductivity detection A standard sample (C ₁₂ H ₈ NO ₂ FClBrS, molecular weight 364.62, S = 8.79%) was used to prepare the calibration curve.

[Measurement of chlorine content of ethylene polymer powder]
After burning the ethylene polymer powder with an automatic sample combustion device (AQF-100 manufactured by Mitsubishi Chemical Analytech Co., Ltd.), it is absorbed by an absorption liquid, and the absorption liquid is absorbed by an ion chromatograph device (Dionex Co., Ltd., ICS1500, column (separation column). : AS12A, guard column: AG12A) Suppressor ASRS300) was injected and the total chlorine content was measured.

[Corrosion (rust resistance) test of ethylene polymer powder]
A 260 mm * 260 mm * 5 mm thick SUS iron plate, a 300 mm * 300 mm * 0.1 mm thick aluminum foil, and a 50 μm thick PET mylar are placed on the top and bottom, and a 50 mm * 50 mm * 2 mm thick SUS316 iron plate ( Place four sheets (hereinafter referred to as SUS plates), pour 160 g of ethylene-based polymer powder, flatten them, and use a compression molding machine (model SFA-37) manufactured by Shinto Metal Mining Co., Ltd. at a temperature of 200 ° C. (1). The operation of degassing (0 MPa) after pressurizing under the condition of (second pressurization) pressure of 15 MPa and 300 seconds, and degassing (0 MPa) after pressurizing under the condition of (secondary pressurization) pressure of 15 MPa and 5 seconds is 5 After performing a cycle and pressurizing under the conditions of (tertiary pressurization) pressure of 15 MPa and 900 seconds to make it normal pressure, compression molding was performed, and then compression cooled to 25 ° C. of the same place compression molding machine (same type). It was cooled at 15 MPa in a molding machine for 600 seconds. The SUS plate that was taken out and was in contact with the ethylene polymer powder was removed.

Place the above SUS plate in an EYELA constant temperature and humidity chamber with a temperature of 60 ° C and a humidity of 90%, and after a certain period of time (20, 40, 60, 120 minutes), check the rust generation status of the sample and use the following criteria. The evaluation was carried out.
○: No rust generated ×: Rust generated

[Measurement of defects in ethylene polymer powder]
In a 100 cc polycup, 4.0 g of ethylene polymer powder and 0.012 g of pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] as an antioxidant (3,5-di-t-butyl-4-hydroxyphenyl) propionate ( 0.3% by mass) was added and dry-blended to obtain a mixture such as a polymer. Further, 36.0 g (polyethylene concentration 10% by mass) of liquid paraffin (kinematic viscosity at 37.78 ° C. 7.59 × ^10-5 m ² / s) was added to the mixture, and the mixture was stirred at room temperature with a spatula. , A uniform slurry was obtained.

The slurry was put into a lab plast mill (4C150-01 type manufactured by Toyo Seiki Seisakusho Co., Ltd.) set at 190 ° C., and kneaded in a nitrogen atmosphere at a rotation speed of 50 rpm for 30 minutes. The mixture (gel) obtained by kneading was compressed with a press heated to 165 ° C. to prepare a gel sheet having a thickness of 1.0 mm. A 10 cm × 10 cm test piece was cut out from the prepared gel sheet, set in a simultaneous biaxial tenter stretching machine heated to 120 ° C., and held for 3 minutes. Then, it was stretched at a speed of 12 mm / sec so that the MD magnification was 7.0 times and the TD magnification was 7.0 times (that is, 7 × 7 times). Next, the stretched sheet was sufficiently immersed in normal hexane to extract and remove liquid paraffin, and then normal hexane was dried and removed. The thin film after the extraction was completed was dried at room temperature for 10 hours. The dried thin film was held over light, and the number of white spots (undissolved) having a diameter of 1 mm or more existing in 30 cm × 30 cm was counted.
The solubility was evaluated according to the following criteria.
◯: The number of defects is 5 or less.
X: The number of defects is more than 5.

[Discoloration resistance of ethylene polymer powder]
Calculated by using a color machine (Z-300A type) manufactured by Nippon Denshoku Kogyo Co., Ltd., using a standard white plate as a reference, and using a press-molded product of an ultra-high molecular weight ethylene polymer of the same size as a sample. Check the color change with the value.
Using a xenon weather meter (type X75) manufactured by Suga Test Instruments Co., Ltd., discoloration resistance was determined by changing the color tone of the sample 50, 100, 250, and 500 hours after irradiation with the xenon lamp.
Discoloration resistance: ○ b value <5
× b value ≧ 5

[Reference example 1]
Catalyst Synthesis Example 1: Preparation of Solid Catalyst Component [A] (1) (A-1) Synthesis of Carrier In an 8 L stainless steel autoclave fully substituted with nitrogen, 1,000 mL of a hexane solution of 2 mol / L hydroxytrichlorosilane was charged. , 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 at 500 rpm at 65 ° C. for 4 hours. The reaction was continued with stirring at 65 ° C. for 1 hour. After completion of the reaction, the supernatant was removed and washed 4 times with 1,800 mL of hexane to obtain a carrier (A-1).
(2) Preparation of Solid Catalyst Component [A] A composition of 110 mL of 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 150 g of the carrier (A-1). 110 mL of a hexane solution of an organic magnesium compound represented by the formula AlMg ₅ (C ₄ H ₉ ) ₁₁ (OSiHCH ₃ ) _{2 was added simultaneously over 1 hour with stirring at 400 rpm.} 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.

[Reference example 2]
Catalyst Synthesis Example 2: Preparation of Metallocene Catalyst The metallocene catalyst is composed of the following solid catalyst [B], liquid component [E] and hydrogenated catalyst [F] (compound having hydrogenation ability).

(Preparation of solid catalyst [B])
In preparing the solid catalyst [B], first, the following silica carrier [B1], transition metal compound component [C], and activator [D] were prepared.

((Preparation of silica carrier [B1]))
As a precursor of the silica carrier [B1], silica having an average particle size of 7 μm, a specific surface area of 660 m ² / g, a pore volume of 1.4 mL / g, and a compression strength of 7 MPa was used.

Silica (130 g) after heat treatment was dispersed in 2500 mL of hexane in a nitrogen-substituted capacity 8 L autoclave to obtain a slurry. To the obtained slurry, 195 mL of a hexane solution (concentration 1M) of triethylaluminum, which is a Lewis acidic compound, was added at 20 ° C. with stirring. Then, the mixture was stirred for 2 hours, and triethylaluminum was reacted with the surface hydroxyl group of silica to prepare 2695 mL of a hexane slurry of silica carrier [B1] on which triethylaluminum was adsorbed.

((Preparation of transition metal compound component [C]))
As the transition metal compound (C-1), [(N-t-butyramide) (tetramethyl-η5-cyclopentadienyl) dimethylsilane] titanium-1,3-pentadiene (hereinafter abbreviated as "complex 1"). It was used. Further, as the organic magnesium compound (C-2), composition formula Mg (C ₂ H ₅ ) (C ₄ H ₉ ) (hereinafter, abbreviated as “Mg 1”) was used.

200 mmol of complex 1 is dissolved in 1000 mL of isoparaffin hydrocarbon (Isoper E manufactured by Exxon Mobile Co., Ltd.), 40 mL of a hexane solution of Mg1 (concentration 1 M) is added thereto, and hexane is further added to adjust the concentration of complex 1 to 0.1 M. Then, the transition metal compound component [C] was obtained.

((Preparation of activator [D]))
As the borate compound (D-1), 17.8 g of bis (taroalkyl hydride) methylammonium-tetrakis (pentafluorophenyl) borate (hereinafter abbreviated as "borate") was added to 156 mL of toluene to dissolve it, and the borate was dissolved. A 100 mmol / L toluene solution was obtained. To this boron solution of boron, 15.6 mL of a 1 mol / L hexane solution of ethoxydiethylaluminum as (D-2) was added at room temperature, and toluene was further added to adjust the volate concentration in the solution to 70 mmol / L. Then, the mixture was stirred at room temperature for 1 hour to prepare an activator [D] containing borate.

By the above operation, a silica carrier [B1], a transition metal compound component [C], and an activator [D] were obtained, and a solid catalyst [B] was prepared as follows.
While stirring 2695 mL of the slurry of the silica carrier [B1] at 400 rpm at 25 ° C., 219 mL of the activator [D] and 175 mL of the transition metal compound component [C] were added from another line using a metering pump at the same time. The solid catalyst [B] was prepared by adding the mixture, adding the mixture for 30 minutes, and then continuing the reaction for 3 hours.

(Preparation of liquid component [E])
As the organic magnesium compound [E1], composition formula AlMg ₆ (C ₂ H ₅ ) ₃ (C ₄ H ₉ ) ₁₂ (hereinafter abbreviated as “Mg 2”) was used.
To a 200 mL flask, 40 mL of hexane and Mg2 were added with stirring at 38.0 mmol as the total amount of Mg and Al, and at 20 ° C., methylhydropolysiloxane (viscosity 20 cm Stokes at 25 ° C.; hereinafter referred to as “siloxane compound”). 40 mL of hexane containing 2.27 g (37.8 mmol) (abbreviated) was added with stirring, and then the temperature was raised to 80 ° C. and the reaction was carried out under stirring for 3 hours to prepare the liquid component [E]. ..

(Preparation of hydrogenated catalyst [F])
37.3 g of titanocene dichloride was introduced with 1 L of hexane into a 2.0 L SUS autoclave equipped with a nitrogen-substituted stirrer. 0.7 mol / L, 429 mL of a (9: 1) mixture of triisobutylaluminum and diisobutylaluminum hydride was added by pump at room temperature over 1 hour with stirring at 500 rpm. After the addition, the line was washed with 71 mL of hexane. Stirring was continued for 1 hour to obtain a dark blue uniform 100 mM / L solution [F].

[Example 1]
A Vessel type 300L polymerization reactor with a stirrer with three swept blades and three baffles was used. The stirring speed of the polymerization reactor was 120 pm. The polymerization temperature was maintained at 75 ° C. by cooling the jacket. Normal hexane was supplied as a solvent at 60 L / hour. The solid catalyst [B] was supplied so that the production rate was 10 kg / hour. As the solid catalyst, Stadis 450 diluted with normal hexane was added at 10 wt% with respect to the solid catalyst. The liquid component [E] was supplied at 6 mmol / hour as the total amount of Mg and Al. Hydrogen was supplied to the feed pipe of the solid catalyst [B] at 4 NL / hour. Continuous polymerization was carried out by supplying ethylene under the conditions of a polymerization temperature of 75 ° C., a polymerization pressure of 0.8 MPaG, and an average residence time of 2.3 hours. The polymerization slurry in the polymerization reactor was guided to a flash tank having a pressure of 0.05 MPaG and a temperature of 60 ° C. so that the level in the polymerization reactor was kept constant, and unreacted ethylene and hydrogen were separated. Next, the ethylene-based polymer slurry is continuously pumped from the flash tank to the centrifuge to separate the polymer and the solvent, and the separated ethylene-based polymer powder is sent to the dryer controlled at 80 ° C. , Dryed while blowing nitrogen.

The polymerization activity of the catalyst was 9,600 g / gs, the viscosity average molecular weight of the obtained ethylene polymer powder PE1 was 300,000, and the bulk density was 0.32 g / cm ³ . The results are shown in Table 1.

[Example 2]
An ethylene polymer powder PE2 was obtained in the same manner as in Example 1 except that a hydrogenation catalyst [F] was separately supplied to the hydrogen feed pipe so that the concentration in the reactor was 0.3 μmol / L. The results are shown in Table 1.

[Example 3]
The same procedure as in Example 1 was carried out except that the feed amount of the hydrogenation catalyst was set to 0.6 μmol / L in the polymerization reactor to obtain an ethylene polymer powder PE3. The results are shown in Table 1.

[Example 4]
An ethylene-based polymer powder PE4 was obtained in the same manner as in Example 1 except that the feed amount of the hydrogenation catalyst was set to 4.0 μmol / L in the polymerization reactor. The results are shown in Table 1.

[Example 5]
As the α-olefin, 1-butene was fed in the same manner as in Example 4 except that the concentration of 1-butene with respect to ethylene in the system (α-olefin / (ethylene + α-olefin)) was 0.13 mol%. Powder PE5 was obtained. The results are shown in Table 1.

[Example 6]
The same procedure as in Example 3 was carried out except that Stadis 450 was added to the flash tank at 10 g / h with respect to the ethylene polymer to obtain an ethylene polymer powder PE6. The results are shown in Table 1.

[Example 7]
An ethylene-based copolymer powder PE7 was obtained in the same manner as in Example 1 except that "dinonylnaphthalene sulfonic acid" was used instead of Stadis 450 added to the solid catalyst. The results are shown in Table 1.

[Comparative Example 1]
An ethylene polymer powder PE8 was obtained in the same manner as in Example 1 except that Stadis450 was not added to the solid catalyst. Extraction from the polymerization reactor often tended to be clogged. The results are shown in Table 1.

[Comparative Example 2]
The same procedure as in Example 1 was carried out except that hydrogen was separately added to the polymerization reactor from the gas phase and the concentration (hydrogen / ethylene + hydrogen) with respect to ethylene in the polymerization reactor was set to 1,700 ppm. Ethylene-based polymer powder PE9 Got The results are shown in Table 1.

[Comparative Example 3]
Ethylene-based polymer powder was carried out in the same manner as in Example 1 except that Stadis450 was not added to the solid catalyst and was separately added to the supply pipe of the liquid component [E] so as to be 25 ppm with respect to the polymerization production rate of 10 kg / h. PE10 was obtained. The results are shown in Table 1.

[Comparative Example 4]
An ethylene-based polymer powder PE11 was obtained in the same manner as in Example 1 except that the stirring speed of the polymerization reactor was set to 500 pm. The results are shown in Table 1.

[Comparative Example 5]
The same polymerization reactor as in Example 1 was used. The polymerization temperature was maintained at 78 ° C. by cooling the jacket. Hexane was supplied to the polymerizer at 60 L / Hr. The solid catalyst component [A] is 1 g / h, and 0.7 mol / L of a mixture of triisobutylaluminum and diisobutylaluminum hydride (9: 1) as a co-catalyst component is used at a rate of 10 mmol / Hr. Added by another introduction line. As the solid catalyst, Stadis 450 diluted with normal hexane was added at 10 wt% with respect to the solid catalyst. Ethylene was continuously supplied to maintain the polymerization pressure at 0.35 MPa. The production rate of the ethylene polymer was maintained at 10 kg / Hr, and the ethylene polymer powder PE12 was obtained. The results are shown in Table 1.

[Comparative Example 6]
The amount of Stadis450 added to the solid catalyst was set to 30 wt%, and 10 g / hr was separately added to the polymerization reactor at a production rate of 10 kg / hr in the same manner as in Example 1. Ethylene-based polymer powder PE13 Got The results are shown in Table 1.

As is clear from the results shown in Table 1, Examples 1 to 7 in which the viscosity average molecular weight, the sulfur content and the chlorine content / sulfur content were within the predetermined ranges were compared with Comparative Examples 1 to 7 in which they were out of the range. Compared with No. 6, it was found that the rust resistance was good, the number of defects was small, and the discoloration resistance was good.

The ethylene-based polymer powder of the present invention can be continuously produced with high productivity, has high strength such as microporous membranes and high-strength fibers, and can be stably produced for a long period of time without causing rust on the molding machine. Since it is possible, there is little discoloration after molding, and it is used for microporous membranes for lithium ion secondary batteries, ropes, nets, bulletproof clothing, protective clothing, protective gloves, fiber reinforced concrete products, helmets, etc. It has industrial potential in a wide range of applications such as strength fiber applications.

Claims (6)

1) The viscosity average molecular weight is 200,000 or more,
2) The sulfur content is in the range of 0.10 or more and 50 ppm or less.
3) The chlorine content / sulfur content ratio is in the range of 0.010 or more and 10 or less.
An ethylene-based polymer powder,
An ethylene polymer powder having a chlorine content of 10 ppm or less in the ethylene polymer powder . Either the ethylene homopolymer (A); or the ethylene copolymer (B).
The ethylene copolymer (B) is
a) Ethylene 75.0% by weight or more and less than 100% by mass,
b) α-olefin having 3 to 20 carbon atoms, cyclic olefin having 3 to 20 carbon atoms, formula CH ₂ =
At least one selected from the group consisting of a compound represented by CHR (where R is an aryl group having 6 to 20 carbon atoms) and a linear, branched or cyclic diene having 4 to 20 carbon atoms. Comonomer, which is a seed olefin, is more than 0% by mass and 25.0% by mass or less.
The ethylene-based polymer powder according to claim 1, which is obtained by copolymerizing the above. A molded product obtained by using the ethylene-based polymer powder according to claim 1 or 2. A separator for a lithium ion secondary battery obtained by using the ethylene-based polymer powder according to claim 1 or 2. A fiber obtained by using the ethylene-based polymer powder according to claim 1 or 2. A press-molded product obtained by using the ethylene-based polymer powder according to claim 1 or 2.