JP6889025B2 - Ethylene copolymer 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, foams, 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 molded by dissolving them in a solvent. In the industrial world, especially in the lithium ion secondary battery separator and high-strength fiber industry, there is a strong demand for cost reduction and high productivity as well as high demand growth. 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.

Here, in recent years, for example, as shown in Patent Documents 1 to 6, a molding method for a lithium ion secondary battery separator, a high-strength fiber, or the like using a high molecular weight ethylene polymer powder has been developed.

Japanese Unexamined Patent Publication No. 2014-133873 Japanese Unexamined Patent Publication No. 2014-133874 Japanese Unexamined Patent Publication No. 2015-21273 Japanese Unexamined Patent Publication No. 2015-157905 Japanese Unexamined Patent Publication No. 2015-168755 International Publication No. 2008/013144

As described above, the high molecular weight ethylene polymer powder used for microporous films, high-strength fibers, etc. (hereinafter, also referred to as "ethylene polymer powder") has no unmelted material and is used during 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, calcium stearate may be concentrated in a solvent that is recovered and recycled after the polymer is dissolved, and in applications such as microporous membranes and high-strength fibers, the presence of concentrated calcium stearate in the molded body is a drawback (for example, microporous). Since relatively large holes in the film, thread breakage of high-strength fibers, etc.) may occur, it is requested not to add a chlorine catcher agent such as calcium stearate. However, since the ethylene polymer powder produced by using the conventional Ziegler-Natta type catalyst contains titanium-chlorine in the solid catalyst, a large amount of titanium-chlorine remains in the molded product when the chlorine catcher agent is not added. I was able to do it. Then, since there is a possibility that the color tone changes from white to yellow immediately after or after molding due to the residual, it is also required to suppress the color tone change after processing.

On the other hand, in order to solve the above problems, it is also important to be able to continuously produce the ethylene-based polymer powder with high productivity. However, when the ethylene-based polymer powder is produced, the polymerization rate of polyethylene is high. In (when productivity is increased), scales such as lumps are generated inside the polymerization reactor due to local rapid polymerization, which may block the extraction line for extracting the slurry containing the ethylene polymer. , The amount of coagulated powder may increase. As a result, the continuous productivity of the ethylene-based polymer powder may be inferior, and improvement thereof is also required.

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. Provided are an ethylene-based polymer powder capable of high productivity, continuous stable operation without use, and capable of suppressing color change of a molded product, and a molded product obtained by using such an ethylene-based polymer powder. The purpose is to do.

Therefore, as a result of intensive studies to achieve the above-mentioned problems, the present inventors have found that a predetermined ethylene-based polymer powder can solve the above-mentioned problems, and have completed the present invention.

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 0.20 ppm or more and 5 ppm or less.
3) The chlorine content is 10 ppm or more and 80 ppm or less.
4) Chlorine content / sulfur content ratio is more than 10 and 80 or less.
Ethylene polymer powder.
[2]
Either the ethylene homopolymer (A); or the ethylene copolymer (B).
The ethylene copolymer (B) is
a) Ethylene 90.00% 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 10.00% by weight or less.
The ethylene-based polymer powder according to the above [1], which is obtained by copolymerizing the above.
[3]
The ethylene polymer powder JIS K-6721: bulk density measured at 1997 is an ethylene according to 0.35 kg / m ³ to 0.60 kg / m ³ and is the [1] or [2] System polymer powder.
[4]
Obtained by using the ethylene polymer powder according to any one of the above [1] to [3].
Molded body.
[5]
Obtained by using the ethylene polymer powder according to any one of the above [1] to [3].
Separator for lithium-ion secondary batteries.
[6]
Obtained by using the ethylene polymer powder according to any one of the above [1] to [3].
Separator for lead-acid batteries.
[7]
Obtained by using the ethylene polymer powder according to any one of the above [1] to [3].
fiber.
[8]
Obtained by using the ethylene polymer powder according to any one of the above [1] to [3].
Press molded body.
[9]
Obtained by using the ethylene polymer powder according to any one of the above [1] to [3].
Lamb extruded body.

According to the present invention, the unmelted product at the time of melting has sufficiently little thread breakage and fluffing at the time of stretching, has high strength after stretching, and is highly productive and continuous without using a chlorine catcher agent such as calcium stearate. It is possible to provide an ethylene-based polymer powder capable of stable operation and 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, and various modifications are made without departing from the gist thereof. Is possible.

[Ultra high molecular weight ethylene polymer powder]
The ultra-high molecular weight ethylene polymer powder according to this embodiment satisfies the following 1) to 4).
1) The viscosity average molecular weight is 200,000 or more;
2) Sulfur content is 0.10 ppm or more and 5 ppm or less;
3) Chlorine content is 10 ppm or more and 80 or less ppm or less;
4) Chlorine content / sulfur content ratio is more than 10 and 80 or less;
By having the above structure, the ethylene polymer powder according to the present embodiment has no unmelted matter at the time of molding, has excellent strength of the obtained molded body, has less thread breakage and fluff at the time of molding, and causes product loss. Few. Further, even if chlorine is contained in the ethylene-based polymer powder, the molded product is less discolored and the quality of the product is sufficiently changed. Further, even in such a case, in the production of the ethylene-based polymer powder, high productivity and continuous stable operation can be performed. Specifically, when producing the above ethylene-based polymer powder, the activity of the polymerization reaction is maintained to increase the productivity, and the scale of lumps or the like generated by local rapid polymerization inside the polymerization reactor is used. Continuous stable production is possible without causing clogging of the slurry extraction line and with less coagulated powder.

[Viscosity average molecular weight]
The viscosity average molecular weight (Mv) of the ethylene polymer powder according to this embodiment 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, the strength of the molded product is improved, and when it is 15,000,000 or less, it is stretched. Workability 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, as another method for setting the viscosity average molecular weight in the above range, changing the organometallic compound species as an auxiliary catalyst used when polymerizing the ethylene-based polymer powder can be mentioned (for example, Japanese Patent No. 0589295). See publications, etc.).

Further, as another method for setting the viscosity average molecular weight in the above range, a chain transfer agent (for example, hydrogen) is added into the polymerization reactor when the ethylene-based polymer powder is polymerized. By adding the chain transfer agent in this way, the viscosity average molecular weight of the ethylene-based polymer produced even at the same polymerization temperature can be controlled.
In the present embodiment, it is preferable to control both in combination.

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 5 ppm or less, more preferably 0.20 ppm or more and 2 ppm or less, and 0.50 ppm or more and 1.5 ppm or less. Is even more preferable.

In the present embodiment, although the reason is not clear, the presence of this sulfur component in the polymer may cause unmelted matter in the molded product, thread breakage, and fluffing, such as a stagnation portion in the polymerization reactor. It was found that it has an effect of suppressing an abnormal polymer or the like which adheres to and grows by polymerization. Then, in order to exert this effect more sufficiently, it was found that the sulfur component is present in the polymer and its content is in the range of 0.10 ppm or more. Further, if the polymerization rate of polyethylene is too fast (activity is too high), it may affect the continuous productivity of the ethylene-based polymer powder. Therefore, by setting the sulfur component content to 0.10 ppm or more, the polymerization rate is high. It is also possible to suppress too much. As a result, it is possible to suppress the generation of scales that may occur due to local rapid polymerization and improve the continuous productivity of the ethylene-based polymer powder. Further, by setting the content of the sulfur component to 5 ppm or less, it is possible to prevent the polymerization rate of polyethylene from being excessively lowered (the activity is too low) and improve the productivity. In addition, when the activity decreases, the powder tends to become fine particles, and when the activity becomes fine particles, it becomes easy to bridge during the transportation of the powder and the fluidity decreases, but the activity is prevented from decreasing too much, so that the handleability of the powder is improved. Can be improved.

Regarding the sulfur content, the following method is carried out while the additiveable sulfur compound described later is present or added to the polymerization system, specifically, a method of adding the solid catalyst and the sulfur compound to the polymerization system at high speed. , A method of adding a sulfur compound to the polymerization system together with a co-catalyst, a method of using a stirring blade with a higher stirring strength such as a three-piece receding blade or an anchor blade for the shape of the stirring blade of the polymerization reactor, a feed port for ethylene to be polymerized. The sulfur content in the ethylene-based polymer polymer can be controlled by setting a plurality of ethylenes and supplying ethylene from each of them. In the above-mentioned "method of adding the solid catalyst and the sulfur compound to the polymerization system at high speed", it is preferable to add the solid catalyst and the sulfur compound at a linear velocity of 1 m / s or more.

Further, as another method for controlling the sulfur content of the ethylene-based polymer powder within the above range, the following method, that is, a polymerization catalyst or a polymerization catalyst, is performed while an addable sulfur compound described later is present or added to the polymerization system. Examples thereof include a method of controlling by a co-catalyst, a polymerization temperature, a polymerization pressure, a slurry concentration, a residence time and the like.

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. Can be derived. As the sulfur compound, an organic sulfur compound is preferable. When the sulfur compound that can be added is present in the system during the polymerization of the ethylene polymer, the degree of proximity of the sulfur component in the sulfur compound to the catalyst (in the slurry at the time of polymerization, the sulfur component is contained on the ethylene polymer side). The activity of the catalyst can vary depending on whether it is contained on the solvent side.
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.
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 amount]
The chlorine content of the ethylene polymer powder of this embodiment is 10 ppm or more and 80 ppm or less. The chlorine content of the ethylene polymer powder is preferably 10 ppm or more and 70 ppm or less, and more preferably 10 ppm or more and 65 ppm or less. By setting the chlorine content to 10 ppm or more, it is possible to prevent the activity of the polymerization reaction (the amount of ethylene-based polymer powder produced per 1 g of the catalyst) from becoming too high, so that the scale that can be generated by local rapid polymerization can be suppressed. The generation can be suppressed and the continuous productivity of the ethylene-based polymer powder can be improved. Further, by setting the chlorine content to 80 ppm or less, it is possible to suppress the activity of the polymerization reaction reaction from becoming too low, so that the productivity can be improved and the handleability of the powder can be improved. Further, by setting the chlorine content to 80 ppm or less, it is possible to suppress the color change due to chlorine derived from the solid catalyst in polyethylene.
As a method of controlling the chlorine content of the ethylene-based polymer powder within the above range, it is controlled by a polymerization catalyst, a co-catalyst, a polymerization temperature, a polymerization pressure, a slurry concentration, a residence time, etc. when polymerizing the ethylene-based polymer. The method can be mentioned.

[Chlorine content / sulfur content ratio]
Chlorine content (ppm) / sulfur content (ppm) of the ethylene polymer powder of this embodiment
) Ratio is preferably more than 10 and 80 or less, more preferably more than 10 and 74 or less, and further preferably more than 10 and 70 or less. By keeping the ratio of chlorine content / sulfur content of the ethylene polymer powder within the above range, the reason is not clear, but a certain amount of sulfur is present with respect to chlorine, and it is derived from the solid catalyst in polyethylene. It is presumed that the change in color due to chlorine can be suppressed. Further, by setting the chlorine content / sulfur content ratio to 80 or less, it is possible to suppress the coarsening of the ethylene polymer powder.
As a method for controlling the chlorine content / sulfur content ratio of the ethylene-based polymer powder within the above range, the following method is specifically performed while an addable sulfur compound is present or added to the polymerization system. A method of adding a sulfur compound and a solid catalyst to the polymerization reaction field at high speed, a method of adding a sulfur compound to the polymerization system together with a co-catalyst, and a method of changing the shape of the stirring blade of the polymerization reactor from three swept blades or anchor blades. It can be controlled by using a stirring blade having high stirring strength, a method of providing a plurality of feed ports for polymerizing ethylene and supplying ethylene from each of them.

Further, as another method of controlling the chlorine content / sulfur content ratio of the ethylene-based polymer powder within the above range, the following method, that is, while adding or adding an addable sulfur compound to the polymerization system, that is, , A method of controlling by a polymerization catalyst or a co-catalyst, a polymerization temperature, a polymerization pressure, a slurry concentration, a residence time and the like can be mentioned.

[The bulk density]
The bulk density of the ethylene polymer powder according to this embodiment is 0.35 g / cm ³ or more and 0.
And at 60 g / cm ³ or less, and more preferably it is preferably at most 0.38 g / cm ³ or more 0.55 g / cm ^3, or less 0.40 g / cm ³ or more 0.50 g / cm ^3. When the bulk density is 0.35 g / cm ³ or more, the fluidity of the ethylene polymer powder becomes sufficiently high, the handleability is excellent, the feed to the extruder is stable, and the stretchability of the film and fibers is improved. Stable film thickness and fiber diameter. In addition, a molded product with less gas entrainment in the molded product and no air bubbles can be obtained. On the other hand, when the bulk density is 0.60 g / cm ³ or less, it is excellent in productivity and / or stretchability when processing into a battery separator or a fiber, and exhibits better processing applicability.

In general, the bulk density varies depending on the solid catalyst used, but can be controlled by the productivity of the ethylene polymer per unit catalyst. Specifically, the bulk density of the ethylene-based polymer can be controlled by the polymerization temperature at the time of polymerization, and the bulk density can be lowered by raising the polymerization temperature. Further, the bulk density of the ethylene-based polymer can 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 ethylene polymer is measured in accordance with JIS K-6721: 1997, but can be specifically measured by the method described in Examples.

[Comonomer concentration]
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 mass ratio of ethylene to the copolymer powder is preferably 90.00% by mass or more and less than 100% by mass, and 95.00% by mass or more and 100%. Less than mass% is more preferable, and 99.00% by mass or more and less than 100% by mass is further preferable. When the mass ratio of ethylene is within the above range, it tends to be more excellent in heat resistance and / or strength.

As a method for controlling the b) comonomer content in the ethylene polymer powder within the above range, b) comonomer / [ethylene + b) comonomer] (mass%) added into the polymerization reactor.
) Can be changed. 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. This is b
) It is considered that this is because 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 small as possible.

In addition, b) The content of the comonomer unit was measured by G.I. 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.

[Method for producing 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 is a Ziegler-Natta catalyst. And as a metallocene catalyst, for example, Patent No. 578.
The Ziegler-Natta catalyst and the metallocene catalyst disclosed in Japanese Patent Publication No. 2558 and Japanese Patent 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 content in the solid catalyst is preferably 1 or more and 500 or less, more preferably 10 or more and 200 or less, and 10 or more and 100 or less. Is even more preferable. 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. Suspension polymerization is preferable from the viewpoint of polymerization or efficient removal of heat from 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, isobutane, pentane, isopentane, hexane, heptane, octane, decane, dodecane, and kerosene; cyclopentane, Aliphatic hydrocarbons such as cyclohexane and methylcyclopentane; and mixtures thereof.

The polymerization temperature in the production method for obtaining the ethylene-based polymer powder of the present embodiment is 4.
It is preferably 0 ° C. or higher and 100 ° C. or lower, more preferably 50 ° C. or higher and 95 ° C. or lower, and further preferably 50 ° C. or higher and 90 ° C. or lower. 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, industrially efficient production is possible. 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 static electricity adhesion of the polymer to the polymerization reactor. Is also possible. In addition, as the sulfur compound, an organic sulfur compound is preferable, and thioether, iophen, 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. The antistatic agent such as Stadis or STATSAFE can also be added to the polymerization reactor by diluting it with an inert hydrocarbon medium by a pump or the like. The amount added at this time is preferably 1 ppm or more and 500 ppm or less, preferably 10 ppm or more, with respect to the production amount of the ethylene-based polymer powder per unit time, such as by adding it to a solid catalyst in advance or adding it to a polymerization reactor. More preferably 100 ppm or less.

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 as described above may be used in combination with 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, but for example, tetrakis [methylene (3).
, 5-Di-t-Butyl-4-hydroxy) hydrocinnamate] Heat stabilizers such as methane, distearylthiodipropionate; or bis (2,2', 6,6'-tetramethyl-4-piperidine) ) Sevacate, weather-resistant stabilizers such as 2- (2-hydroxy-t-butyl-5-methylphenyl) -5-chlorobenzotriazole and the like can be mentioned. In addition, stearate salts such as calcium stearate, magnesium stearate, and zinc stearate, which are known as lubricants and hydrogen chloride absorbers, can also be mentioned as suitable additives.

Molded products, high-strength fibers, and lithium-ion battery separators can be obtained from the ethylene-based polymer powder of the present embodiment.

[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-mentioned ethylene-based polymer powder, undissolved substances are suppressed, so that defects in the above-mentioned molded product can be reduced. 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 cannon-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 amount of the above ethylene polymer powder is 7 mg.
The fall time (ts) between the marked lines was measured in the same manner for the samples changed to 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-based 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.

[Measurement of white spots on 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. In addition, liquid paraffin (37.7) was added to the mixture.
A uniform slurry was obtained by adding 36.0 g (polyethylene concentration 10% by mass) having a kinematic viscosity at 8 ° C. of 7.59 × ^10-5 m ^{2 / s and stirring with a spatula at room temperature.}
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, defects) 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.
◯: Number of white spots, 5 or less ×: Number of white spots, more than 5

[Discoloration resistance of ethylene polymer powder]
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 ethylene-based polymer polymer of the same size as a sample, with the b value calculated. , Check the discoloration resistance.
Discoloration resistance: ○ b value: less than 1
× b value: 1 or more

The press-molded product of the ethylene-based polymer polymer was molded by the following method.
Place 260 mm * 260 mm * 5 mm thick SUS iron plate, 300 mm * 300 mm * 0.1 mm thick aluminum foil, and 50 μm thick PET film on the top and bottom, pour 160 g of ethylene polymer powder into it, and flatten it. Using a compression molding machine (model SFA-37) manufactured by Mining Co., Ltd., pressure was applied at a temperature of 200 ° C. under the conditions of (primary pressurization) pressure of 15 MPa and 300 seconds, and then degassed (0 MPa) and (secondary pressurization). Pressurization) pressure 15MPa, pressurize for 5 seconds, then degas (0MPa) for 5 cycles, and pressurize (3rd pressurization) pressure 15MPa, 900 seconds to normal pressure. After compression molding in the process, it was cooled at 15 MPa for 600 seconds in a compression molding machine cooled to 25 ° C. of the same place compression molding machine (same type).

[Coagulated powder content]
The ratio of not passing 100 g of ethylene-based polymer powder was calculated using a sieve with a mesh opening of 35 mesh (opening 425 μm) described in JIS X 8801-1 (2006).
Agglomerated particle ratio: ○ Less than 1 wt%
× 1 wt% or more

[Reference example]
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, and 500 rpm at 65 ° C. 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 was added dropwise over 4 hours while stirring with.} Further, 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. As a result of analyzing this solid ((A-1) carrier), magnesium contained in 1 g of the solid was 8.31 mmol.

(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 above (A-1) carrier. 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.

[Example 1]
A vessel-type 300L polymerization reactor with a stirring blade of three swept blades and three baffles was used. The stirring speed of the polymerization reactor was 230 prm. The polymerization temperature was maintained at 83 ° C. by cooling the jacket. Normal hexane was supplied as a solvent at 80 L / hour. The solid catalyst [A] was supplied so that the production rate was 10 kg / hour. As the solid catalyst, Stadis 450 diluted with normal hexane was added at 5 wt% with respect to the solid catalyst. Triisobutylaluminum and diisobutylaluminum hydride (9: 1 mixture) were supplied as co-catalyst components at 10 mmol / hour. Hydrogen was supplied at 13 mol% (hydrogen / ethylene + hydrogen molar ratio). The polymerization temperature was 83 ° C., the polymerization pressure was 0.5 MPaG, and the average residence time was 1.8 hours. Ethylene was supplied to the liquid phase through three feed ports to carry out continuous polymerization in the polymerization reactor. 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 was continuously pumped from the flash tank to the centrifuge to separate the polymer and the solvent, and the separated ultra-high molecular weight ethylene-based polymer powder was dried at 80 ° C. It was sent to a machine and dried while blowing nitrogen.
As for the polymerization activity of the catalyst, the viscosity average molecular weight of the ethylene-based polymer PE1 obtained at 20,000 g / gs was 300,000, and the bulk density was 0.51 g / cm ³ . The results are shown in Table 1.

[Example 2]
The ultrahigh molecular weight ethylene polymer PE2 was obtained in the same manner as in Example 1 except that the hydrogen concentration was supplied to 78 ° C. at a polymerization temperature of 5 mol%. The results are shown in Table 1.

[Example 3]
The same procedure as in Example 1 was carried out except that the hydrogen content was 2000 ppm, to obtain an ethylene polymer PE3. The results are shown in Table 1.

[Example 4]
The same as in Example 3 except that the polymerization temperature was 75 ° C. and 1-butene was fed as α-olefin by 0.25 mol% as the concentration (α-olefin / ethylene + α-olefin) with respect to ethylene in the system. This was carried out to obtain an ethylene-based polymer PE4. The 1-butene content in the ethylene polymer powder was 0.05 mol%. The results are shown in Table 1.

[Example 5]
The polymerization temperature was 59 ° C., the polymerization pressure was 0.5 MPa, 6 Mg (C ₄ H ₉ ) ₁₂ AL (C ₂ H ₅ ) ₃ was used as an co-catalyst, and the same procedure as in Example 4 was carried out except that hydrogen was not added. , Ethylene-based polymer PE5 was obtained. The results are shown in Table 1.

[Example 6]
An ethylene polymer PE6 was obtained in the same manner as in Example 3 except that dinonylsulfonic acid was used instead of Stadis450 added to the solid catalyst. The results are shown in Table 1.

[Comparative Example 1]
An ethylene polymer PE7 was obtained in the same manner as in Example 1 except that Stadis450 was not added to the solid catalyst. Clumps were formed and extraction from the polymerization reactor often tended to be clogged. The results are shown in Table 1.

[Comparative Example 2]
An ethylene-based polymer PE8 was obtained in the same manner as in Example 1 except that Stadis450 diluted with normal hexane was added to the solid catalyst at 30 wt% with respect to the solid catalyst. The polymerization activity of the catalyst was significantly reduced to 4,000 g / gs. The results are shown in Table 1.

[Comparative Example 3]
An ethylene polymer PE9 was obtained in the same manner as in Example 1 except that the hydrogen concentration was set to 30 mol%. The results are shown in Table 1.

[Comparative Example 4]
An ethylene-based polymer PE10 was obtained in the same manner as in Example 1 except that the stirring blades of the polymerization reactor were 6 turbine blades. Clumps were formed and extraction from the polymerization reactor often tended to be clogged. The results are shown in Table 1.

[Comparative Example 5]
An ethylene polymer PE11 was obtained in the same manner as in Example 1 except that one ethylene feed port was used. Clumps were formed near the ethylene feed port, and the extraction from the polymerization reactor tended to be clogged. The results are shown in Table 1.

[Comparative Example 6]
An ethylene-based polymer PE12 was obtained in the same manner as in Example 1 except that Stadis450 diluted with normal hexane was added to the solid catalyst at 20 wt% with respect to the solid catalyst. The results are shown in Table 1.

As is clear from the results shown in Table 1, Examples 1 to 6 in which the viscosity average molecular weight, the sulfur content, the chlorine content and the sulfur content / sulfur content were within the predetermined ranges were excluded from the range. It was found that the discoloration resistance was good, the number of white spots was small, and the content of the agglomerated powder was low as compared with Comparative Examples 1 to 6.

The ethylene-based polymer powder of the present invention has sufficiently little unmelted matter at the time of melting, thread breakage and fluffing at the time of stretching, high strength after stretching, and is high even without using a chlorine catcher agent such as calcium stearate. Continuous stable operation is possible with productivity, and it is possible to suppress changes in the color tone of molded products. Further, the molded product of the present invention is obtained by using the ethylene-based polymer powder, and since the powder exerts the above-mentioned effect, a microporous film for a lithium ion secondary battery, a rope, a net, a bulletproof garment, etc. It can be used in a wide range of applications such as high-strength fiber applications used in protective clothing, protective gloves, fiber reinforced concrete products, helmets, and the like.

Claims (9)

1) The viscosity average molecular weight is 200,000 or more,
2) The sulfur content is 0.20 ppm or more and 5 ppm or less.
3) The chlorine content is 10 ppm or more and 80 ppm or less.
4 ) The ratio of chlorine content / sulfur content is more than 10 and 80 or less.
Ethylene polymer powder. Either the ethylene homopolymer (A); or the ethylene copolymer (B).
The ethylene copolymer (B) is
a) Ethylene 90.00% 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 10.00% by weight or less.
The ethylene-based polymer powder according to claim 1, which is obtained by copolymerizing the above. The ethylene-based polymer powder according to claim 1 or 2, wherein the ethylene-based polymer powder has a bulk density of 0.35 kg / m ³ or more and 0.60 kg / m ^{3 or less as measured by JIS K-6721: 1997.} .. A molded product obtained by using the ethylene polymer powder according to any one of claims 1 to 3. A separator for a lithium ion secondary battery obtained by using the ethylene-based polymer powder according to any one of claims 1 to 3. A separator for a lead storage battery obtained by using the ethylene-based polymer powder according to any one of claims 1 to 3. A fiber obtained by using the ethylene-based polymer powder according to any one of claims 1 to 3. A press-molded article obtained by using the ethylene-based polymer powder according to any one of claims 1 to 3. A ram extruded product obtained by using the ethylene polymer powder according to any one of claims 1 to 3.