Polyethylene powder and molded body obtained using the same

Abstract

The present invention relates to a polyethylene powder and a molded body obtained using the polyethylene powder. The present invention provides a polyethylene powder having excellent processability, excellent production speed at the time of molding of a molded body, and capable of improving the yield of qualified products, uniformity of properties, and the like by suppressing reduction in strength caused by void defects or insufficient fusion, and a molded body obtained using the polyethylene powder, and the like. A polyethylene powder, wherein the polyethylene powder has a viscosity average molecular weight Mv of 100,000 (g / mol) to 10,000,000 (g / mol), has an average particle diameter X of 50 μm to 200 μm on a cumulative mass basis 50 , a difference ΔMv (here, ΔMv = Mv 75 - Mv 150 ) between a viscosity average molecular weight Mv 75 (g / mol) of undersize powder when classified using a sieve having a mesh size of 75 μm and a viscosity average molecular weight Mv 150 (g / mol) of oversize powder when classified using a sieve having a mesh size of 150 μm is greater than 0 (g / mol) and less than or equal to 4,000,000 (g / mol), and a ratio a / b of a bulk density a (g / cm 3 ) to a tap density b (g / cm 3 ) is 83.0 (%) or greater.

Description

TECHNICAL FIELD

[0001] The present application relates to a polyethylene powder and a molded body or the like obtained using the polyethylene powder. BACKGROUND

[0002] Compared with general polyethylene, an ultrahigh molecular weight polyethylene powder having a high molecular weight is more excellent in wear resistance, impact resistance, self-lubricating property, chemical resistance, low-temperature property, dimensional stability, lightness, safety to food, and the like, compared with other engineering plastics or metals. Therefore, its molded body is used in various fields such as inner liner materials for ships or trucks, gears or bearings for machines, rollers for food transportation, backer materials for ski boards, artificial bones or artificial joints, and the like.

[0003] An ultrahigh molecular weight polyethylene is difficult to melt-knead the resin because of its low melt flowability due to its high molecular weight. Therefore, as a molding method, in most cases, the molding is performed by compression molding, plunger extrusion molding, screw extrusion molding, or the like, in which a raw material resin in powder form is directly heated and compressed. Moreover, as problems in the molding of an ultrahigh molecular weight polyethylene, there can be listed: slow processing speed, poor productivity; void defects or strength reduction due to poor filling of the powder and insufficient fusion of the powders to each other, low yield of qualified products accompanying therewith, and particularly, the larger the molded body, the greater the difference in properties between the central portion and the end portions of the molded body. These problems hinder the use of the ultrahigh molecular weight polyethylene molded body in a wider range.

[0004] In order to solve these problems, several methods have been studied. For example, in Patent Literature 1, a method is reported in which by mixing a low molecular weight polyethylene having a molecular weight of 5,000 to 20,000 in an ultrahigh molecular weight polyethylene having a molecular weight of 1 million or more, the productivity can be improved.

[0005] In addition, in Patent Literature 2, a method is reported in which by making the molecular weight distribution narrow using a special cross-linking metallocene catalyst system, the processability can be improved.

[0006] Further, in Patent Literature 3, a method is reported in which by making the molecular weight distribution and the particle size distribution narrow, the productivity at the time of compression molding can be improved.

[0007] In addition, in Patent Literature 4, a method is reported in which by performing a special heat treatment on the powder, the powder spread parameter defined by oneself can be adjusted, the generation of void defects can be suppressed, and the yield of qualified products can be improved.

[0008] PRIOR ART DOCUMENTS

[0009] PATENT LITERATURE

[0010] Patent Literature 1: Japanese Patent Application Laid-Open No. 57-177036

[0011] Patent Literature 2: Japanese Patent Application Laid-Open No. 2009-514997

[0012] Patent Literature 3: Japanese Patent Application Laid-Open No. 2017-141312

[0013] Patent Literature 4: WO 2020 / 171017 SUMMARY

[0014] PROBLEMS TO BE SOLVED BY THE INVENTION

[0015] According to the method described in Patent Literature 1, although an improvement in production speed at the time of molding is confirmed, at the same time, a problem of a large decrease in the molded body properties, particularly, abrasion resistance, is generated. In addition, an improvement in yield, a variation in properties is not considered.

[0016] According to the method described in Patent Literature 2, it is reported that the processability can be improved by narrowing the molecular weight distribution. However, the effect thereof is not specifically shown, in addition, an improvement in yield, a variation in properties is not considered.

[0017] According to the method described in Patent Literature 3, it is reported that the processability is improved by narrowing the molecular weight distribution and the particle size distribution. It is presumed that an effect in the production speed, the suppression of void defects is exhibited, however, the effect thereof is not specifically shown, in addition, an improvement in yield, a variation in properties is not considered.

[0018] According to the method described in Patent Literature 4, it is reported that the generation of void defects can be suppressed, and the yield can be improved. However, for a larger-sized molded body, the performance thereof cannot satisfy the requirements. In addition, an improvement in production speed, a variation in properties is not considered.

[0019] Therefore, in the present application, in view of the above problems, an object is to provide a polyethylene powder having excellent processability, excellent in production speed at the time of molding of a molded body, and capable of improving the yield, uniformity in properties, and the like, by suppressing the strength reduction caused by void defects or insufficient fusion, and a molded body, and the like, obtained using the polyethylene powder.

[0020] MEANS FOR SOLVING THE PROBLEMS

[0021] The present inventors and others have made intensive studies in order to solve the above problems, as a result, it has been surprisingly found that a polyethylene powder having a difference between the viscosity average molecular weight of a powder having a large particle diameter and a powder having a small particle diameter at the time of classifying the polyethylene powder using a sieve having a predetermined mesh size, and a predetermined ratio between the bulk density and the tap density, can solve the above problems, thereby completing the present application. That is, the present application is as follows. [1]

[0023] A polyethylene powder, wherein

[0024] The polyethylene powder has a viscosity average molecular weight Mv of 100,000 (g / mole) to 10,000,000 (g / mole),

[0025] The polyethylene powder has an average particle size X of 50 μm to 200 μm based on cumulative mass. 50 ,

[0026] The viscosity average molecular weight Mv of the powder under the sieve when the polyethylene powder is classified using a sieve with a mesh size of 75 μm 75 (g / mole) and the viscosity average molecular weight Mv of the powder on the sieve when the polyethylene powder is classified using a sieve with a mesh size of 150 μm 150 (g / mole) difference ΔMv (here, ΔMv=Mv 75 -Mv 150 ) is greater than 0 (g / mole) and less than or equal to 4,000,000 (g / mole), and

[0027] The bulk density of the polyethylene powder is a (g / cm 3 ) relative to tap density b(g / cm 3 ) ratio a / b is 83.0(%) or more. [2]

[0029] The polyethylene powder as described in [1], wherein the ratio a / b is greater than 88.0(%). [3]

[0031] The polyethylene powder according to [1] or [2], wherein the difference ΔMv is greater than 10 (g / mol) and less than or equal to 3,000,000 (g / mol). [4]

[0033] A molded body obtained by molding a raw material containing the polyethylene powder according to any one of [1] to [3]. [5]

[0035] A press-molded body obtained by press-molding a raw material comprising the polyethylene powder according to any one of [1] to [3]. [6]

[0037] An extruded article obtained by extrusion molding a raw material comprising the polyethylene powder according to any one of [1] to [3]. [7]

[0039] A microporous membrane comprising the polyethylene powder described in any one of [1] to [3]. [8]

[0041] A high-strength fiber comprising the polyethylene powder described in any one of [1] to [3].

[0042] Effects of the Invention

[0043] According to the present invention, there can be provided a polyethylene powder having a specific viscosity-average molecular weight difference ΔMv and a specific ratio a / b of bulk density a to tap density b, excellent processability, excellent production speed during molding of molded bodies, and the ability to improve the yield rate and uniformity of physical properties, and a molded body obtained using the polyethylene powder. DETAILED DESCRIPTION

[0044] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") is described in detail. It should be noted that the following embodiments are examples for illustrating the present invention, and the present invention is not limited thereto. That is, the present invention can be implemented with any changes within the scope of its purpose. It should be noted that in this specification, when "to" is used and numerical values ​​or physical property values ​​are inserted before and after it for expression, it is used as a range including the values ​​before and after it.

[0045] [Polyethylene powder]

[0046] The polyethylene powder of this embodiment (hereinafter also referred to simply as "powder") has a viscosity average molecular weight Mv of 100,000 (g / mol) to 10,000,000 (g / mol) and an average particle size X of 50 μm to 200 μm on a cumulative mass basis. 50 The viscosity average molecular weight Mv of the powder under the sieve when the sieve is classified using a sieve with a mesh size of 75 μm 75 (g / mole) and the viscosity average molecular weight Mv of the powder on the sieve when classified using a sieve with a mesh size of 150 μm 150 (g / mole) difference ΔMv (here, ΔMv=Mv 75 -Mv 150 ) is greater than 0 (g / mole) and less than or equal to 4,000,000 (g / mole), and the bulk density a (g / cm 3 ) relative to tap density b(g / cm 3 ) ratio a / b is 83.0(%) or more.

[0047] The polyethylene powder in this embodiment refers to an aggregate of polyethylene particles.

[0048] Examples of the polyethylene constituting the polyethylene powder of this embodiment include, but are not limited to, ethylene homopolymers and copolymers of ethylene and other comonomers.

[0049] There are no particular limitations on other comonomers, and examples thereof include α-olefins and vinyl compounds.

[0050] The α-olefins are not particularly limited, and examples thereof include α-olefins having 3 to 20 carbon atoms. Specific examples of α-olefins having 3 to 20 carbon atoms include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, and 1-tetradecene. Among these α-olefins, propylene and 1-butene are preferred from the perspectives of impact resistance, wear resistance, heat resistance, and rigidity of the resulting polyethylene powder molded article.

[0051] The vinyl compound is not particularly limited, and examples thereof include vinylcyclohexane, styrene, and derivatives thereof.

[0052] Furthermore, non-conjugated polyenes such as 1,5-hexadiene and 1,7-octadiene may be used as other comonomers as needed.

[0053] The other comonomers may be used alone or in combination of two or more.

[0054] The content of other comonomers is not particularly limited; however, the content of other comonomers is preferably 0.8 mol% or less, more preferably 0.7 mol% or less, and even more preferably 0.6 mol% or less, relative to the polyethylene. Adjusting the amount of other comonomers to 0.8 mol% or less tends to produce molded articles with excellent impact resistance, wear resistance, and rigidity. When other comonomers are used, there is no particular lower limit on the amount of other comonomers; the amount of other comonomers relative to the polyethylene can be greater than 0 mol%.

[0055] The comonomer content of polyethylene can be confirmed by NMR analysis or infrared analysis as described in the examples below.

[0056] [Viscosity average molecular weight Mv]

[0057] The viscosity average molecular weight Mv (g / mol) of the polyethylene powder of the present embodiment is 100,000 to 10,000,000, preferably 500,000 to 9,000,000, and more preferably 1,000,000 to 8,000,000.

[0058] By the viscosity average molecular weight Mv being 100,000 (g / mole) or more, the molded body obtained by molding the polyethylene powder of the present embodiment has a tendency that the impact resistance and the wear resistance are further improved. In addition, by the viscosity average molecular weight Mv being 10,000,000 (g / mole) or less, the polyethylene powder has a tendency that the melting of the powder and the fusion of the powders with each other are promoted at the time of molding the powder, so that the production speed at the time of molding is further improved, the void defects caused by the insufficient fusion are further suppressed, and the variation in the properties within the molded body is further reduced.

[0059] Note that the viscosity average molecular weight Mv of the polyethylene powder can be adjusted by using the catalyst described later and appropriately adjusting the polymerization conditions and the like. As the polymerization conditions, specifically, the presence of hydrogen in the polymerization system and / or the change in the polymerization temperature and the like can be exemplified. In addition, the viscosity average molecular weight Mv of the polyethylene powder can be found by the method described in the examples described later.

[0060] [average particle diameter X 50 ]

[0061] The average particle diameter X 50 of the polyethylene powder of the present embodiment is the particle diameter at which the cumulative mass is 50 mass% (sieve analysis particle diameter), that is, the median particle diameter. The average particle diameter X 50 of the polyethylene powder can be calculated by the method described in the examples described later. The average particle diameter X 50 of the polyethylene powder is 50 μm to 200 μm, preferably 60 μm to 175 μm, and more preferably 70 μm to 150 μm. By the average particle diameter X 50 of the polyethylene powder being 200 μm or less, the polyethylene powder is easily melted, so that the production speed at the time of molding is improved, the generation of the void defects caused by the insufficient fusion can be suppressed, and the variation in the properties within the molded body can be reduced. In addition, by the average particle diameter X 50 of the polyethylene powder being 50 μm or more, the scattering of the powder can be suppressed, so that the operability at the time of handling the powder has a tendency to be improved.

[0062] The average particle diameter X 50 of the polyethylene powder can be controlled by sieving using a sieve having a specific mesh size. In the present embodiment, from the viewpoint of the solubility in a solvent, the polyethylene powder that has passed through a sieve having a mesh size of 425 μm according to the standard sieve according to the JIS Z8801 standard is particularly preferably used.

[0063] [difference ΔMv]

[0064] The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm 75 The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm 150 The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm 75 The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm 150 The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm The difference ΔMv is greater than 0 (g / mole) and equal to or less than 4,000,000 (g / mole), preferably greater than 5 (g / mole) and equal to or less than 3,500,000 (g / mole), more preferably greater than 10 (g / mole) and equal to or less than 3,000,000 (g / mole). By the difference ΔMv being greater than 0 (g / mole), the viscosity average molecular weight Mv of the large particle diameter powder is less than the viscosity average molecular weight Mv of the small particle diameter powder, and as a result, the melting of the large particle diameter powder, which has a slow heat transfer, and the fusion of the powders with each other become relatively easy to perform, the production rate during molding processing is further improved, void defects caused by insufficient fusion are further suppressed, and the tendency for variation in properties within the molded body is further reduced. On the other hand, by the difference ΔMv being 4,000,000 (g / mole) or less, the viscosity average molecular weight Mv of the large particle diameter powder is suppressed from becoming too low. As a result, the tendency for the impact resistance and wear resistance of the molded body to be further improved. In addition, at the same time, the viscosity average molecular weight Mv of the small particle diameter powder is suppressed from becoming too high, and as a result, the melting of the small particle diameter powder, and the fusion of the powders with each other become easy to perform, the production rate during molding processing is further improved, void defects caused by insufficient fusion are further suppressed, and the tendency for variation in properties within the molded body is further reduced.

[0065] The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm 75 The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm 150 The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm 75 The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm 150 The difference ΔMv is the difference between the viscosity average molecular weight Mv of the powder that passed through the sieve (hereinafter also referred to as "sieve undersize powder") when the polyethylene powder was classified using a sieve having a mesh size of 75 μm

[0066] As a method for controlling the difference ΔMv to be within a range greater than 0 (g / mole) and equal to or less than 4,000,000 (g / mole), there is no particular limitation, and for example, a method in which the polymerization method is selected can be cited. When a specific example is cited, a method in which a catalyst described later is used in the polymerization reaction of the polyethylene and is carried out in two steps (hereinafter also referred to as "two-step polymerization") can be cited, and a method in which polyethylene having a lower molecular weight is obtained in the first step of the two-step polymerization, and a method in which the second step of the two-step polymerization is carried out under the same conditions as the first step, and the like can be cited.

[0067] The reason for being able to control the difference ΔMv using the above method will be explained. Low molecular weight polyethylene having a certain particle size distribution is produced in the first step polymerization. For the large particle size powder after the first step polymerization, the catalyst activity decreases, and the speed of ethylene diffusion to the catalyst in the center of the powder becomes slow, so the polymerization reaction is difficult to proceed at the time of high molecular weight polyethylene polymerization in the second step. On the other hand, for the small particle size powder after the first step polymerization, the catalyst activity does not decrease as much as the large particle size powder, and the speed of ethylene diffusion to the catalyst in the center of the powder is relatively fast, so the polymerization reaction is easy to proceed at the time of high molecular weight polyethylene polymerization in the second step. As a result, for the powder after the second step polymerization, the viscosity average molecular weight Mv can be increased as the particle size becomes small. Note that as a method of controlling ΔMv within a prescribed range, adjustment of the molecular weight of the first step and the second step, adjustment of the particle size distribution of the first step, and the like can be cited.

[0068] As another method of controlling the difference ΔMv within a range of greater than 0 (g / mol) and less than or equal to 4,000,000 (g / mol), a polymerization method in which a parallel polymerization reaction is performed using a catalyst described later and using two polymerizers, and then the polymerization slurry is mixed (hereinafter also referred to as "parallel polymerization") can be cited, and the low molecular weight polyethylene having a large particle size and the high molecular weight polyethylene having a small particle size obtained respectively are mixed. As a method of controlling the particle size of the powder, adjustment of the activity of the catalyst and the like can be cited, and specifically, changing the polymerization pressure, the catalyst addition amount, and the like can be cited.

[0069] Further, as another method of controlling the difference ΔMv within a range of greater than 0 (g / mol) and less than or equal to 4,000,000 (g / mol), a method in which a plurality of polyethylene powders having different particle sizes and viscosity average molecular weights Mv are mixed by dry blending can be cited.

[0070] [Proportion a / b]

[0071] In the present specification, the bulk density a refers to the apparent density (g / cm3) at the time of free fall of the polyethylene powder. 3 The tap density b refers to the apparent density (g / cm3) after tapping the free-fallen powder 180 times. 3). The bulk density a and the tap density b can be obtained by the method described in the Examples described later, and the value of the ratio a / b (%) can be obtained from the values of the bulk density a and the tap density b according to the formula: ratio a / b = 100 x a / b. That is, the closer the ratio a / b is to 100 (%), the more closely the powder is packed in the free-falling stage. The ratio a / b is preferably 83.0 (%) or more, more preferably 86.0 (%) or more, and even more preferably 88.0 (%) or more. There is no particular limitation on the upper limit, as long as it is 100 (%) or less. By having the ratio a / b be 83.0 (%) or more, the powder is easily packed closely, and the powder easily fuses with each other, so that the generation of void defects during the molding process can be suppressed, and there is a tendency for the variation in properties within the molded body to be further reduced.

[0072] As a method for controlling the ratio a / b to be 83.0 (%) or more, there is no particular limitation, and for example, the following can be mentioned: designing the polymerization method, the polymerization conditions, and the cooling method of the powder, etc.

[0073] First, specific examples of the polymerization method and the polymerization conditions for controlling the ratio a / b to be 83.0 (%) or more will be described. As the polymerization method, the following can be mentioned: the method using the above-described two-step polymerization or the method using the parallel polymerization. As the polymerization conditions for the two-step polymerization, the following can be mentioned: making the polymerization reaction in the second step proceed sharply. As the polymerization conditions for the parallel polymerization, the following can be mentioned: polymerizing to obtain large-particle-size polyethylene in one polymerizer, and polymerizing to obtain small-particle-size polyethylene in another polymerizer, and making the polymerization reaction in the polymerization to obtain small-particle-size polyethylene proceed sharply. As specific examples of the polymerization conditions for making the polymerization reaction proceed sharply, the following can be mentioned: adding a large amount of the cocatalyst described later, increasing the polymerization pressure, etc. By using such a polymerization method and manufacturing the polyethylene powder under such polymerization conditions, as the particle size becomes smaller, the surface irregularities of the powder particles become rough, and by this specific powder morphology, the ratio a / b can be increased compared to the past. By forming this specific powder morphology, the contact area of the large-particle-size powder having few surface irregularities with the small-particle-size powder having rough surface irregularities is reduced, and in the free-falling stage, the small-particle-size powder is closely packed in the gaps of the large-particle-size powder, so that the value of the ratio a / b can be increased. Note that in the case where both the large-particle-size powder and the small-particle-size powder have rough surface irregularities, the surface irregularities of each other become a resistance, so that the value of the ratio a / b becomes small.

[0074] The reason why the surface of the powder particles becomes rough with the decrease in the particle diameter after the two-step polymerization in the above-described specific example is described. As described above, the small particle diameter powder after the first step polymerization is easily subjected to the second step polymerization, i.e., particle growth, and the small particle diameter powder is difficult to disperse the stress at the time of the particle growth, and thus, compared with the large particle diameter powder, the cracks are easily generated on the surface of the powder, and as a result, the surface of the powder particles becomes rough with the decrease in the particle diameter after the two-step polymerization.

[0075] Next, as a specific example for controlling the ratio a / b to be 83.0(%) or more, the cooling method of the powder is described. After the polymerized powder is dried, the powder is rapidly cooled while the powder is stirred, and thus, the surface of the powder particles can be made rough with the decrease in the particle diameter. This is because the small particle diameter powder is easily cooled, and the stress accompanying the volume shrinkage at the time of the cooling is difficult to disperse.

[0076] [Method for producing polyethylene powder]

[0077] [Catalyst component]

[0078] As the catalyst component used in the production of the polyethylene powder of the present embodiment, there is no particular limitation, and for example, a general Ziegler-Natta catalyst can be exemplified.

[0079] (Ziegler-Natta catalyst)

[0080] As the Ziegler-Natta catalyst, an olefin polymerization catalyst comprising a solid catalyst component [A] and an organometallic compound component [B] is preferable, wherein the solid catalyst component [A] is produced by reacting an organic magnesium compound (A-1) soluble in an inert hydrocarbon solvent represented by the following (Formula 1) with a titanium compound (A-2) represented by the following (Formula 2).

[0081] (A-1): (M 1 ) α (Mg) β (R 2 ) a (R 3 ) b (Y 1 ) c … (Formula 1)

[0082] (In Formula 1, M 1 is a metal atom belonging to a group consisting of Group 12, Group 13, and Group 14 of the periodic table, R 2 and R 3 are hydrocarbon groups having 2 or more and 20 or less carbon atoms, and Y 1hydrocarbyloxy group, a siloxy group, an allyloxy group, an amino group, an amido group, -N=C-R 4 5 6 4 5 6 1 1

[0083] 7 d 1 (4-d)

[0084] 7 1

[0085] Note that the inert hydrocarbon solvent used in the reaction of the organomagnesium compound (A-1) with the titanium compound (A-2) is not particularly limited, and examples thereof include aliphatic hydrocarbons such as pentane, hexane, and heptane; aromatic hydrocarbons such as benzene and toluene; and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane.

[0086] First, the organomagnesium compound (A-1) will be described.

[0087] The organomagnesium compound (A-1) is represented in the form of an organomagnesium complex that is soluble in an inert hydrocarbon solvent, and includes all of dihydrocarbylmagnesium compounds and complexes of the compounds with other metal compounds. The relationship nα+2β=a+b+c of the symbols α, β, a, b, and c represents the valence of a metal atom and the stoichiometry of a substituent.

[0088] In (Formula 1), the hydrocarbyl groups represented by R 2 and R 3 are not particularly limited as long as they are hydrocarbyl groups having 2 or more and 20 or less carbon atoms, and are, for example, an alkyl group, a cycloalkyl group, or an aryl group, and specifically, examples thereof include an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a cyclohexyl group, a phenyl group, and the like. An alkyl group is particularly preferred. In the case where α>0, the metal atom M 1 ​​​​​​​​​​​​​​​As the metal atom belonging to the group consisting of Group 12, Group 13 and Group 14 of the periodic table, for example, zinc, boron, aluminum and the like can be cited. Aluminum and zinc are particularly preferable.

[0089] The ratio β / α of the magnesium to the metal atom M 1 The ratio β / α of the magnesium to the metal atom M 2 In the case where R 2 is 1-methylpropyl or the like, is soluble in an inert hydrocarbon solvent, and such a compound also gives preferable results in the present embodiment.

[0090] In the above (Formula 1), R 2 , R 3 satisfy any one of the three groups (1), (2), (3) shown below.

[0091] Group (1): At least one of R 2 and R 3 is a secondary or tertiary alkyl group having 4 or more and 6 or less carbon atoms, and preferably R 2 and R 3 are both alkyl groups having 4 to 6 carbon atoms, and at least one of R 2 and R 3 is a secondary or tertiary alkyl group.

[0092] Group (2): R 2 and R 3 are alkyl groups having different numbers of carbon atoms, and preferably R 2 is an alkyl group having 2 or 3 carbon atoms, and R 3 is an alkyl group having 4 or more carbon atoms.

[0093] Group (3): At least one of R 2 and R 3 is a hydrocarbon group having 6 or more carbon atoms, and preferably is an alkyl group having a total number of carbon atoms of 12 or more when the numbers of carbon atoms contained in R 2 and R 3 are added.

[0094] Hereinafter, these groups are specifically shown.

[0095] In the above Group (1), as the secondary or tertiary alkyl group having 4 or more and 6 or less carbon atoms, for example, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, 2-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, 2-methyl-2-ethylpropyl and the like can be cited. 1-Methylpropyl is particularly preferable.

[0096] In addition, as the alkyl group having 2 or 3 carbon atoms in the above-mentioned group (2), for example, ethyl group, 1-methylethyl group, propyl group, and the like can be exemplified. Among them, ethyl group is particularly preferable. In addition, as the alkyl group having 4 or more carbon atoms, there is no particular limitation, and specifically, for example, butyl group, pentyl group, hexyl group, heptyl group, octyl group, and the like can be exemplified. Among them, butyl group and hexyl group are particularly preferable.

[0097] Further, as the hydrocarbon group having 6 or more carbon atoms in the above-mentioned group (3), there is no particular limitation, and for example, hexyl group, heptyl group, octyl group, nonyl group, decyl group, phenyl group, 2-naphthyl group, and the like can be exemplified. Among the hydrocarbon groups, alkyl group is preferable, and among the alkyl groups, hexyl group and octyl group are particularly preferable.

[0098] Generally, as the number of carbon atoms contained in the alkyl group increases, there is a tendency to easily dissolve in the inert hydrocarbon solvent, and in addition, there is a tendency that the viscosity of the solution becomes high. Therefore, in terms of handling, it is preferable to use an alkyl group having an appropriate chain length. Note that the above-mentioned organic magnesium compound can be used after being diluted with an inert hydrocarbon solvent, and even if a trace amount of a Lewis base compound such as an ether, an ester, an amine, or the like is contained or remains in the solution, it can be used without problems.

[0099] Next, Y 1 will be described.

[0100] In the above-mentioned (Formula 1), Y 1 is any one of a hydrocarbon oxy group, a silyloxy group, an allyloxy group, an amino group, an amido group, -N=C-R 4 , -SR 5 , -SR 6 (here, R 4 , R 5 , and R 6 each independently represent a hydrocarbon group having 2 or more and 20 or less carbon atoms), or a β-keto acid residue.

[0101] In the above-mentioned (Formula 1), as the hydrocarbon group represented by R 4 , R 5 , and R 6 , an alkyl group or an aryl group having 1 or more and 12 or less carbon atoms is preferable, and an alkyl group or an aryl group having 3 or more and 10 or less carbon atoms is more preferable. There is no particular limitation, and for example, methyl group, ethyl group, propyl group, 1-methylethyl group, butyl group, 1-methylpropyl group, 1,1-dimethylethyl group, pentyl group, hexyl group, 2-methylpentyl group, 2-ethylbutyl group, 2-ethylpentyl group, 2-ethylhexyl group, 2-ethyl-4-methylpentyl group, 2-propylheptyl group, 2-ethyl-5-methyl octyl group, octyl group, nonyl group, decyl group, phenyl group, naphthyl group, and the like can be exemplified. Among them, butyl group, 1-methylpropyl group, 2-methylpentyl group, and 2-ethylhexyl group are particularly preferable.

[0102] Further, in the above (Formula 1), Y 1 is preferably a hydrocarbon group or a silyl group.

[0103] As the hydrocarbon group, there is no particular limitation, and for example, methoxy, ethoxy, propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 1,1-dimethylethoxy, pentoxy, hexyloxy, 2-methylpentoxy, 2-ethylbutoxy, 2-ethylpentoxy, 2-ethylhexyloxy, 2-ethyl-4-methylpentoxy, 2-propylheptoxy, 2-ethyl-5-methyloctyloxy, octyloxy, phenoxy, naphthoxy are preferable. Particularly more preferable are butoxy, 1-methylpropoxy, 2-methylpentoxy, and 2-ethylhexyloxy.

[0104] As the silyl group, there is no particular limitation, and for example, dimethylhydrogen silyloxy, ethylhydrogenmethyl silyloxy, diethylhydrogen silyloxy, trimethyl silyloxy, ethyldimethyl silyloxy, diethylmethyl silyloxy, triethyl silyloxy, and the like are preferable. Particularly more preferable are dimethylhydrogen silyloxy, ethylhydrogenmethyl silyloxy, diethylhydrogen silyloxy, and trimethyl silyloxy.

[0105] The synthesis method of the above organic magnesium compound (A-1) is not particularly limited, and for example, it can be synthesized by reacting an organic magnesium compound belonging to the group consisting of a compound represented by Formula R 2 MgX 1 and a compound represented by Formula R 2 Mg(R 2 is the aforementioned meaning, X 1 is a halogen atom) with an organometallic compound belonging to the group consisting of a compound represented by Formula M 1 R 3 n and M 1 R 3 (n-1) H(M 1 and R 3 is the aforementioned meaning, n represents the valence of M 1 ) in an inert hydrocarbon solvent at a temperature of 25°C or higher and 150°C or lower, and then, as necessary, reacting a compound represented by Formula Y 1 -H(Y 1 is the aforementioned meaning) or reacting an organic magnesium compound and / or an organic aluminum compound having a functional group represented by Y 1 . Among them, in the case of reacting an organic magnesium compound soluble in an inert hydrocarbon solvent with a compound represented by Formula Y 1 -H, there is no particular limitation to the order of the reaction, and for example, a method in which the compound represented by Formula Y 1 -H is added to the organic magnesium compound, a method in which the compound represented by Formula Y 1-H represents either the method in which the organic magnesium compound is added to the compound or the method in which both are added at the same time.

[0106] Y in the above organic magnesium compound (A-1) 1 The molar composition ratio c / (a+β) with respect to the total metal atoms is preferably 0≤c / (a+β)≤2, more preferably 0≤c / (a+β)<1. By Y 1 The molar composition ratio is 2 or less with respect to the total metal atoms, and the tendency of the reactivity of the organic magnesium compound (A-1) with the titanium compound (A-2) is improved.

[0107] Next, the titanium compound (A-2) will be described.

[0108] The titanium compound (A-2) is a titanium compound represented by the following Formula 2.

[0109] (A-2): Ti(OR 7 ) d X 1 (4-d) ... (Formula 2)

[0110] (In Formula 2, d is a real number of 0 or more and 4 or less, R 7 is a hydrocarbon group having 1 or more and 20 or less carbon atoms, and X 1 is a halogen atom.)

[0111] In the above (Formula 2), d is preferably 0 or more and 1 or less, and further preferably 0.

[0112] In addition, the hydrocarbon group represented by R 7 in the above (Formula 2) is not particularly limited, and for example, aliphatic hydrocarbon groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, a decyl group, and an allyl group; alicyclic hydrocarbon groups such as a cyclohexyl group, a 2-methylcyclohexyl group, and a cyclopentyl group; and aromatic hydrocarbon groups such as a phenyl group and a naphthyl group can be exemplified. An aliphatic hydrocarbon group is particularly preferable.

[0113] The halogen atom represented by X 1 may be exemplified by a chlorine atom, a bromine atom, and an iodine atom. A chlorine atom is particularly preferable. The above titanium compound (A-2) is particularly preferably titanium tetrachloride. In the present embodiment, two or more compounds selected from the above can be used in mixture.

[0114] Next, the reaction of the organic magnesium compound (A-1) with the titanium compound (A-2) will be described.

[0115] The reaction is preferably carried out in an inert hydrocarbon solvent, more preferably in an aliphatic hydrocarbon solvent such as hexane, heptane, or the like. The molar ratio of the organomagnesium compound (A-1) to the titanium compound (A-2) in the reaction is not particularly limited, and the molar ratio of the Ti atom contained in the titanium compound (A-2) to the Mg atom contained in the organomagnesium compound (A-1) (Ti / Mg) is preferably 0.1 or greater and 10 or less, more preferably 0.3 or greater and 3 or less.

[0116] The reaction temperature is not particularly limited, and the reaction is preferably carried out in a range of -80°C or greater and 150°C or less, more preferably in a range of -40°C or greater and 100°C or less.

[0117] The order of addition of the organomagnesium compound (A-1) and the titanium compound (A-2) is not particularly limited, and any one of a method in which the organomagnesium compound (A-1) is added first and then the titanium compound (A-2) is added, a method in which the titanium compound (A-2) is added first and then the organomagnesium compound (A-1) is added, and a method in which the organomagnesium compound (A-1) and the titanium compound (A-2) are added at the same time can be employed, and a method in which the organomagnesium compound (A-1) and the titanium compound (A-2) are added at the same time is preferred. In the present embodiment, the solid catalyst component [A] obtained by the above reaction is used in the form of a slurry solution obtained using an inert hydrocarbon solvent.

[0118] As another example of the Ziegler-Natta catalyst component used in the present embodiment, an olefin polymerization catalyst including a solid catalyst component [C] and an organometallic compound component [B] is preferred, the solid catalyst component [C] is produced by supporting a soluble-in-inert-hydrocarbon-solvent organomagnesium compound (C-4) represented by the following (Formula 5) and a titanium compound (C-5) represented by the following (Formula 6) on a support (C-3) prepared by the reaction of a soluble-in-inert-hydrocarbon-solvent organomagnesium compound (C-1) represented by the following (Formula 3) and a chlorinating agent (C-2) represented by the following (Formula 4).

[0119] (C-1) : (M 2 ) γ (Mg) δ (R 8 ) e (R 9 ) f (OR 10 ) g … (Formula 3)

[0120] (In Formula 3, M 2 is a metal atom belonging to a group consisting of Group 12, Group 13, and Group 14 of the periodic table, R 8 , R 9 , and R10 Each is a hydrocarbon group having 1 to 20 carbon atoms, and γ, δ, e, f, and g are real numbers satisfying the following relationship: 0≤γ, 0<δ, 0≤e, 0≤f, 0≤g, 0<e+f, 0≤g / (γ+δ)≤2, kγ+2δ=e+f+g (here, k represents M 2 valence of atoms.

[0121] (C-2): H h SiCl i R 11 (4-(h+i)) ...(Formula 4)

[0122] (In Formula 4, R 11 is a hydrocarbon group having 1 or more and 12 or less carbon atoms, and h and i are real numbers satisfying the following relationship: 0<h, 0<i, 0<h+i≤4)

[0123] (C-4): (M 1 ) α (Mg) β (R 2 ) a (R 3 ) b Y 1 c ...(Formula 5)

[0124] (In Formula 5, M 1 is a metal atom belonging to the group consisting of Group 12, Group 13 and Group 14 of the periodic table, R 2 and R 3 is a hydrocarbon group having 2 or more and 20 or less carbon atoms, Y 1 is alkoxy, silyloxy, allyloxy, amino, amide, -N=CR 4 ,R 5 、-SR 6 (Here, R 4 、R 5 and R 6 represents a hydrocarbon group having 1 to 20 carbon atoms. 1 (may be different from each other), any of the β-keto acid residues, α, β, a, b and c are real numbers satisfying the following relationship. 0≤α, 0<β, 0≤a, 0≤b, 0≤c, 0<a+b, 0≤c / (α+β)≤2, nα+2β=a+b+c (here, n represents M 1 valence of atoms.

[0125] (C-5): Ti(OR 7 ) d X 1 (4-d)... (Formula 6)

[0126] (In Formula 6, d is a real number of 0 or more and 4 or less, R 7 is a hydrocarbon group having 1 or more and 20 or less carbon atoms, X 1 is a halogen atom.)

[0127] First, the organic magnesium compound (C-1) will be described. The organic magnesium compound (C-1) is represented in the form of an organic magnesium complex that is soluble in an inert hydrocarbon solvent, but includes a dihydrocarbylmagnesium compound and complexes of this compound with other metal compounds all together. The relationship kγ + 2δ = e + f + g of the symbols γ, δ, e, f, and g of Formula 3 indicates the valence of the metal atom and the stoichiometry of the substituents.

[0128] In the above Formula 3, the hydrocarbon groups represented by R 8 to R 9 are not particularly limited, and are each, for example, an alkyl group, a cycloalkyl group, or an aryl group, and specifically, examples that can be given are a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a cyclohexyl group, a phenyl group, and the like. Among these, it is preferable that R 8 and R 9 each be an alkyl group. In the case where α > 0, as the metal atom M 2 , a metal atom belonging to the group consisting of Group 12, Group 13, and Group 14 of the periodic table can be used, and examples that can be given are zinc, boron, aluminum, and the like. Aluminum and zinc are particularly preferable.

[0129] The ratio δ / γ of the magnesium to the metal atom M 2 is not particularly limited, and is preferably 0.1 or more and 30 or less, and more preferably 0.5 or more and 10 or less. In the case where an organic magnesium compound in which γ = 0 is used, for example, in the case where R 8 is a 1-methylpropyl group or the like, is soluble in an inert hydrocarbon solvent, and such a compound also enables preferable results in the present embodiment.

[0130] In the above (Formula 3), in the case where γ = 0, R 8 , R 9 are preferably any one of the three groups (1), (2), and (3) shown below.

[0131] Group (1): At least one of R 8 and R 9 is a secondary alkyl group or a tertiary alkyl group having 4 or more and 6 or less carbon atoms, preferably both R 8 and R 9 have 4 or more and 6 or less carbon atoms, and at least one of R 8 and R 9 is a secondary alkyl group or a tertiary alkyl group.

[0132] Group (2): R 8 and R 9 is an alkyl group having a number of carbon atoms different from R 8 is an alkyl group having a number of carbon atoms of 2 or 3, and R 9 is an alkyl group having a number of carbon atoms of 4 or more.

[0133] Group (3): R 8 and R 9 at least one of R 8 and R 9 is an alkyl group having a number of carbon atoms of 12 or more.

[0134] Hereinafter, these groups are specifically shown.

[0135] As the secondary or tertiary alkyl group having a number of carbon atoms of 4 or more and 6 or less in Group (1), for example, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, 2-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, 2-methyl-2-ethylpropyl, and the like can be used. Particularly preferably, 1-methylpropyl is used.

[0136] Further, as the alkyl group having a number of carbon atoms of 2 or 3 in Group (2), for example, ethyl, 1-methylethyl, propyl, and the like can be listed. Particularly preferably, ethyl is used. Further, as the alkyl group having a number of carbon atoms of 4 or more, there is no particular limitation, and for example, butyl, pentyl, hexyl, heptyl, octyl, and the like can be listed. Particularly preferably, butyl, hexyl is used.

[0137] Furthermore, as the hydrocarbon group having a number of carbon atoms of 6 or more in Group (3), there is no particular limitation, and for example, hexyl, heptyl, octyl, nonyl, decyl, phenyl, 2-naphthyl, and the like can be listed. Among the hydrocarbon groups, an alkyl group is preferred, and among the alkyl groups, particularly preferably, hexyl, octyl is used.

[0138] Generally, when the number of carbon atoms contained in the alkyl group increases, there is a tendency to easily dissolve in an inert hydrocarbon solvent, and there is a tendency for the viscosity of the solution to become high. Therefore, in terms of handling, it is preferable to use an alkyl group of an appropriate length. Note that the aforementioned organic magnesium compound is used in the form of an inert hydrocarbon solution, and even if a trace amount of a Lewis base compound such as an ether, an ester, an amine, or the like is contained or remains in the solution, it can be used without problems.

[0139] Next, the hydrocarbon oxy group (OR 10 ) in the aforementioned (Formula 3) is described.

[0140] As the hydrocarbon oxy group (OR 10The hydrocarbon group represented by is preferably an alkyl group or an aryl group having 1 to 12 carbon atoms, and particularly preferably an alkyl group or an aryl group having 3 to 10 carbon atoms. 10 , are not particularly limited, and examples thereof include methyl, ethyl, propyl, 1-methylethyl, butyl, 1-methylpropyl, 1,1-dimethylethyl, pentyl, hexyl, 2-methylpentyl, 2-ethylbutyl, 2-ethylpentyl, 2-ethylhexyl, 2-ethyl-4-methylpentyl, 2-propylheptyl, 2-ethyl-5-methyloctyl, octyl, nonyl, decyl, phenyl, and naphthyl. Particularly preferred are butyl, 1-methylpropyl, 2-methylpentyl, and 2-ethylhexyl.

[0141] There is no particular limitation on the method for synthesizing the organomagnesium compound (C-1). The preferred method is: 8 MgX 1 Japanese R 8 Mg(R 8 For the above meaning, X 1 The organic magnesium compound in the group consisting of halogen atoms) and the organic magnesium compound belonging to the formula M 2 R 9 k Japanese M 2 R 9 (k-1) H(M 2 、R 9 and k are the above-mentioned meanings) is reacted in an inert hydrocarbon solvent at a temperature of 25° C. to 150° C., and then, if necessary, with a metal having R 9 (R 9 The alcohol of the hydrocarbon group represented by R 9 The hydrocarbyl group represented by the hydrocarbyl group is reacted with a magnesium alkoxide compound and / or an aluminum alkoxide compound.

[0142] When an organomagnesium compound soluble in an inert hydrocarbon solvent is reacted with an alcohol, the order of the reactions is not particularly limited, and any of the following methods may be used: a method of adding the alcohol to the organomagnesium compound, a method of adding the organomagnesium compound to the alcohol, or a method of adding both simultaneously.

[0143] The reaction ratio of the organomagnesium compound soluble in an inert hydrocarbon solvent and the alcohol is not particularly limited. As a result of the reaction, the molar composition ratio of the hydrocarbyloxy groups in the obtained organomagnesium compound containing hydrocarbyloxy groups to all metal atoms, g / (γ+δ), is preferably 0 ≤ g / (γ+δ) ≤ 2, and more preferably 0 ≤ g / (γ+δ) < 1.

[0144] Next, the chlorinating agent (C-2) will be described. The chlorinating agent (C-2) is a chlorinated silicon compound having at least one Si-H bond represented by the following (Formula 4).

[0145] (C-2): H h SiCl i R 11 (4-(h+i)) ... (Formula 4)

[0146] (In Formula 4, R 11 is a hydrocarbon group having 1 or more and 12 or less carbon atoms, and h and i are real numbers satisfying the following relationships. 0 < h, 0 < i, and 0 < h + i ≤ 4)

[0147] In the above (Formula 4), the hydrocarbon group represented by R 11 is not particularly limited, and is, for example, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic hydrocarbon group, and specifically, for example, a methyl group, an ethyl group, a propyl group, a 1-methylethyl group, a butyl group, a pentyl group, a hexyl group, an octyl group, a decyl group, a cyclohexyl group, a phenyl group, or the like can be mentioned. Among them, an alkyl group having 1 to 10 carbon atoms is preferred, and an alkyl group having 1 to 3 carbon atoms such as a methyl group, an ethyl group, a propyl group, and a 1-methylethyl group is more preferred. In addition, h and i are numbers satisfying the relationship of h + i ≤ 4 and greater than 0, and i is preferably 2 or more and 3 or less.

[0148] As these compounds, for example, HSiCl3, HSiCl2CH3, HSiCl2C2H5, HSiCl2(C3H7), HSiCl2(2-C3H7), HSiCl2(C4H9), HSiCl2(C6H5), HSiCl2(4-Cl-C6H4), HSiCl2(CH=CH2), HSiCl2(CH2C6H5), HSiCl2(1-C 10 H7), HSiCl2(CH2CH=CH2), H2SiCl(CH3), H2SiCl(C2H5), HSiCl(CH3)2, HSiCl(C2H5)2, HSiCl(CH3)(2-C3H7), HSiCl(CH3)(C6H5), HSiCl(C6H5)2, and the like can be mentioned. A chlorinated silicon compound containing these compounds or a mixture of two or more selected from among these compounds can be used. Among them, HSiCl3, HSiCl2CH3, HSiCl(CH3)2, and HSiCl2(C3H7) are preferred, and HSiCl3 and HSiCl2CH3 are more preferred.

[0149] Next, the reaction of the above organic magnesium compound (C-1) with the chlorinating agent (C-2) will be described. At the time of the reaction, it is preferable to use an inert hydrocarbon solvent, 1,2-dichloroethane, o-dichlorobenzene, dichloromethane, or the like, a chlorinated hydrocarbon; diethyl ether, tetrahydrofuran, or the like, an ether medium, or a mixed medium thereof, to dilute the chlorinating agent (C-2) and then use it. Among these, from the viewpoint of the performance of the catalyst, an inert hydrocarbon solvent is more preferable.

[0150] The reaction ratio of the organic magnesium compound (C-1) with the chlorinating agent (C-2) is not particularly limited, and the silicon atom contained in the chlorinating agent (C-2) is preferably 0.01 mol or more and 100 mol or less, more preferably 0.1 mol or more and 10 mol or less, relative to 1 mol of the magnesium atom contained in the organic magnesium compound (C-1).

[0151] The reaction method of the organic magnesium compound (C-1) with the chlorinating agent (C-2) is not particularly limited, and any one of a method in which the organic magnesium compound (C-1) and the chlorinating agent (C-2) are simultaneously introduced into a reactor and simultaneously reacted, a method in which the chlorinating agent (C-2) is previously introduced into a reactor and then the organic magnesium compound (C-1) is introduced into the reactor, or a method in which the organic magnesium compound (C-1) is previously introduced into a reactor and then the chlorinating agent (C-2) is introduced into the reactor can be used. Among these, a method in which the chlorinating agent (C-2) is previously introduced into a reactor and then the organic magnesium compound (C-1) is introduced into the reactor is preferable. The support (C-3) obtained by the above reaction is preferably separated by filtration or decantation, and then sufficiently washed with an inert hydrocarbon solvent, so as to remove unreacted substances or by-products, and the like.

[0152] The reaction temperature of the organic magnesium compound (C-1) with the chlorinating agent (C-2) is not particularly limited, and is preferably 25°C or higher and 150°C or lower, more preferably 30°C or higher and 120°C or lower, and further preferably 40°C or higher and 100°C or lower.

[0153] In the method of simultaneous addition in which the organic magnesium compound (C-l) and the chlorinating agent (C-2) are simultaneously introduced into the reactor and reacted, it is preferable to adjust the temperature of the reactor to a prescribed temperature in advance and adjust the temperature in the reactor to a prescribed temperature while the simultaneous addition is performed, thereby adjusting the reaction temperature to a prescribed temperature. In the method in which the organic magnesium compound (C-l) is introduced into the reactor after the chlorinating agent (C-2) is added to the reactor, it is preferable to adjust the temperature of the reactor to which the chlorinating agent (C-2) is added to a prescribed temperature and adjust the temperature in the reactor to a prescribed temperature while the organic magnesium compound is introduced into the reactor, thereby adjusting the reaction temperature to a prescribed temperature. In the method in which the chlorinating agent (C-2) is introduced into the reactor after the organic magnesium compound (C-l) is added to the reactor, it is preferable to adjust the temperature of the reactor to which the organic magnesium compound (C-l) is added to a prescribed temperature and adjust the temperature in the reactor to a prescribed temperature while the chlorinating agent (C-2) is introduced into the reactor, thereby adjusting the reaction temperature to a prescribed temperature.

[0154] Next, the organic magnesium compound (C-4) is described. As (C-4), a compound represented by the above (Formula 5) is preferable.

[0155] (C-4): (M 1 ) α (Mg) β (R 2 ) a (R 3 ) b Y 1 c (Formula 5)

[0156] (In Formula 5, M 1 is a metal atom belonging to a group consisting of Group 12, Group 13 and Group 14 of the periodic table, R 2 and R 3 are hydrocarbon groups having 2 or more and 20 or less carbon atoms, Y 1 is any one of a hydrocarbon oxy group, a siloxy group, an allyloxy group, an amino group, an amido group, -N=C-R 4 , -SR 5 (In this case, R 6 , R 4 and R 5 represent hydrocarbon groups having 1 or more and 20 or less carbon atoms. In the case where c is 2, Y 6 may be different from each other), a β-keto acid residue, α, β, a, b and c are real numbers satisfying the following relationships. 0≤α, 0<β, 0≤a, 0≤b, 0 1 a+b, 0≤c / (α+β)≤2, nα+2β=a+b+c (where n represents M1 valence of the atom.

[0157] The amount of use of the organomagnesium compound (C-4) is preferably 0.1 or more and 10 or less, more preferably 0.5 or more and 5 or less, in terms of the molar ratio of the magnesium atom contained in the organomagnesium compound (C-4) to the titanium atom contained in the titanium compound (C-5).

[0158] The reaction temperature of the organomagnesium compound (C-4) and the titanium compound (C-5) is not particularly limited, and is preferably in the range of -80°C or higher and 150°C or lower, more preferably -40°C or higher and 100°C or lower.

[0159] The concentration when the organomagnesium compound (C-4) is used is not particularly limited, and is preferably 0.1 mol / L or more and 2 mol / L or less, more preferably 0.5 mol / L or more and 1.5 mol / L or less, in terms of the magnesium atom contained in the organomagnesium compound (C-4). Note that an inert hydrocarbon solvent is preferably used in the dilution of the organomagnesium compound (C-4).

[0160] The order of adding the organomagnesium compound (C-4) and the titanium compound (C-5) to the support (C-3) is not particularly limited, and can be any one of adding the titanium compound (C-5) after adding the organomagnesium compound (C-4), adding the organomagnesium compound (C-4) after adding the titanium compound (C-5), and simultaneously adding the organomagnesium compound (C-4) and the titanium compound (C-5). Of these, the method of simultaneously adding the organomagnesium compound (C-4) and the titanium compound (C-5) is preferred. The reaction of the organomagnesium compound (C-4) and the titanium compound (C-5) is performed in an inert hydrocarbon solvent, and an aliphatic hydrocarbon solvent such as hexane or heptane is preferably used. The catalyst thus obtained is used in the form of a slurry solution obtained using an inert hydrocarbon solvent.

[0161] Next, the titanium compound (C-5) will be described. In the present embodiment, (C-5) is the aforementioned titanium compound represented by (Formula 6).

[0162] (C-5): Ti(OR 7 ) d X 1 (4-d) (Formula 6)

[0163] (In Formula 6, d is a real number of 0 or more and 4 or less, R 7 is a hydrocarbon group having 1 or more and 20 or less carbon atoms, and X 1 is a halogen atom.)

[0164] In the above (Formula 6), as R 7The hydrocarbon group represented by R1in the formula (1) is not particularly limited, and examples thereof include aliphatic hydrocarbon groups such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a 2-ethylhexyl group, a heptyl group, an octyl group, a decyl group, and an allyl group; alicyclic hydrocarbon groups such as a cyclohexyl group and a 2-methylcyclohexyl group; and aromatic hydrocarbon groups such as a phenyl group and a naphthyl group. Among these, an aliphatic hydrocarbon group is preferred. As the compound (C-5) of titanium selected from the above, one kind alone can be used, or two or more kinds can be used in combination. 1 The halogen atom represented by X in the formula (1) is not particularly limited, and examples thereof include a chlorine atom, a bromine atom, and an iodine atom. Among these, a chlorine atom is preferred. The compound (C-5) of titanium selected from the above can be used alone or in combination with two or more kinds.

[0165] The amount of use of the compound (C-5) of titanium is not particularly limited, and is preferably 0.01 or more and 20 or less, more preferably 0.05 or more and 10 or less, in terms of the molar ratio of the titanium atom contained in the compound (C-5) of titanium to the magnesium atom contained in the carrier (C-3).

[0166] The reaction temperature of the compound (C-5) of titanium is not particularly limited, and is preferably in the range of -80°C or higher and 150°C or lower, more preferably -40°C or higher and 100°C or lower.

[0167] In the present embodiment, the method of supporting the compound (C-5) of titanium on the carrier (C-3) is not particularly limited, and a method of reacting the compound (C-5) of titanium in excess with respect to the carrier (C-3), a method of effectively supporting the compound (C-5) of titanium by using a third component, or a method of supporting by the reaction of the compound (C-5) of titanium and the organic magnesium compound (C-4) is preferably used.

[0168] Next, the organic metal compound component [B] used in the present embodiment will be described. The solid catalyst component used in the present embodiment becomes a highly active polymerization catalyst by being combined with the organic metal compound component [B]. The organic metal compound component [B] is sometimes referred to as a "cocatalyst". As the organic metal compound component [B], a compound containing a metal belonging to a group consisting of Group 1, Group 2, Group 12, and Group 13 of the periodic table is preferred, and an organoaluminum compound and / or an organomagnesium compound is particularly preferred.

[0169] As the organoaluminum compound used as the above-mentioned organic metal compound component [B], a compound represented by the following formula (7) is preferably used alone or in combination.

[0170] AlR 12 j Z 1 (3-j) … (Formula 7)

[0171] (In the formula (7), R 12Z is a hydrocarbon group having 1 or more and 20 or less carbon atoms, and 1 is a group belonging to the group consisting of a hydrogen atom, a halogen atom, a hydrocarbon oxy group, an allyloxy group, a siloxy group, and j is a number of 2 or more and 3 or less.

[0172] In the above (Formula 7), the hydrocarbon group having 1 or more and 20 or less carbon atoms represented by R 12 is not particularly limited, and includes, for example, an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and an alicyclic hydrocarbon group. As specific examples of the organoaluminum compound, there are preferred trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, tri(2-methylpropyl)aluminum (or triisobutylaluminum), tripentylaluminum, tri(3-methylbutyl)aluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, and the like, trialkylaluminum; diethylaluminum chloride, ethylaluminum dichloride, di(2-methylpropyl)aluminum chloride, ethylaluminum sesquichloride, diethylaluminum bromide, and the like, halogenated aluminum compounds; ethoxydiethylaluminum, butoxydi(2-methylpropyl)aluminum, and the like, hydrocarbyloxyaluminum compounds; dimethylhydrogen silyloxydimethylaluminum, ethylmethylhydrogen silyloxydiethylaluminum, ethyldimethylsilyloxydiethylaluminum, and the like, silyloxyaluminum compounds; and mixtures thereof. The trialkylaluminum compound is particularly preferred.

[0173] As the organomagnesium compound used as the above-mentioned organometallic compound component [B], there is preferred an organomagnesium compound represented by the above-mentioned (Formula 3) which is soluble in an inert hydrocarbon solvent.

[0174] (M 2 ) γ (Mg) δ (R 8 ) e (R 9 ) f (OR 10 ) g … (Formula 3)

[0175] (In Formula 3, M 2 is a metal atom belonging to the group consisting of Group 12, Group 13, and Group 14 of the periodic table, R 8 , R 9 , and R 10 are each a hydrocarbon group having 1 or more and 20 or less carbon atoms, and γ, δ, e, f, and g are real numbers satisfying the following relationships. 0≤γ, 0<δ, 0≤e, 0≤f, 0≤g, 0<e+f, 0≤g / (γ+δ)≤2, kγ+2δ=e+f+g (here, k represents the valence of M 2 .)

[0176] The organic magnesium compound is represented as an organic magnesium complex which is soluble in an inert hydrocarbon solvent, but includes all dialkylmagnesium compounds and complexes of the compound with other metal compounds. As to γ, δ, e, f, g, M 2 8 9 10 As already explained, the organic magnesium compound is preferably highly soluble in the inert hydrocarbon solvent, and therefore δ / γ is preferably in the range of 0.5 or more and 10 or less, and further more preferably M 2 is a compound of aluminum.

[0177] Note that the combination ratio of the solid catalyst component and the organometallic compound component [B] is not particularly limited, and the organometallic compound component [B] is preferably 1 millimole or more and 3,000 millimoles or less with respect to 1 g of the solid catalyst component.

[0178] [Polymerization conditions]

[0179] In the production of the polyethylene powder of the present embodiment, the polymerization method is not particularly limited, and from the viewpoint of being able to efficiently remove the polymerization heat, it is preferable to use a slurry polymerization method to polymerize a monomer containing ethylene alone or ethylene. Further, it is preferable to use a multi-step polymerization in which polymerization is performed in two or more steps with different reaction conditions, or a parallel polymerization in which polymerization is performed in two or more reactors with different reaction conditions and the products are mixed.

[0180] In the slurry polymerization method, an inert hydrocarbon medium can be used as the medium.

[0181] As the above-mentioned inert hydrocarbon medium, there is no particular limitation, and for example, aliphatic hydrocarbons such as propane, butane, isobutane, pentane, isopentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as chloroethane, chlorobenzene, and dichloromethane; and mixtures thereof can be exemplified.

[0182] In the polymerization step of the polyethylene powder, it is preferable to use an inert hydrocarbon medium having a carbon number of 6 or more and 10 or less. By having a carbon number of 6 or more, low-molecular-weight components generated by side reactions during the polymerization of ethylene and the deterioration of the polyethylene are more easily dissolved, and can be easily removed in the step of separating the polyethylene and the polymerization medium. By having a carbon number of 10 or less, there is a tendency that the adhesion of the polyethylene powder to the reaction tank and the like can be suppressed, and therefore, an industrially stable operation can be performed.

[0183] The polymerization reaction can be performed in any one of a batch, a semi-continuous, and a continuous method, but it is preferable to perform the polymerization in a continuous method.

[0184] ​​​By continuously supplying ethylene gas, solvent, catalyst, etc. into the polymerization system and continuously discharging them together with the produced polyethylene, a local high temperature state caused by a sharp ethylene reaction can be suppressed, and the polymerization system can be made more stable. When ethylene is reacted in a uniform state in the system, the generation of branches, double bonds, etc. in the polymer chain can be suppressed, and the low molecular weight of the polyethylene, crosslinking, etc. are less likely to occur, and thus the residual un-melted material at the time of melting or fusing of the ultra-high molecular weight polyethylene powder is reduced, coloring can be suppressed, and problems such as a decrease in mechanical properties are less likely to occur. Therefore, a more uniform continuous system in the polymerization system is preferred.

[0185] The polymerization temperature is usually 30°C or higher and 100°C or lower, preferably 35°C or higher and 95°C or lower, and more preferably 40°C or higher and 90°C or lower. By making the polymerization temperature 30°C or higher, it is possible to perform manufacturing that is industrially effective. By making the polymerization temperature 100°C or lower, it is possible to perform continuous stable manufacturing.

[0186] The polymerization pressure is usually 1 atm or higher and 5.0 MPa or lower, preferably 0.1 MPa or higher and 4.0 MPa or lower, and more preferably 0.1 MPa or higher and 3.0 MPa or lower.

[0187] In the polymerization of the polyethylene powder of the present embodiment, in the case of using continuous two-step polymerization in which two polymerization reactions different in reaction conditions are continuously performed, it is preferred that a polyethylene having a lower molecular weight than that of the second step be polymerized in the first step. The molecular weight of the polyethylene can be controlled, for example, by making hydrogen gas exist in the polymerization system, by using a method of changing the polymerization temperature, etc. as described in the specification of German Patent Application Publication No. 3127133. In addition, by adding hydrogen gas as a chain transfer agent in the polymerization system, it is easy to control the molecular weight within an appropriate range. In the case of adding hydrogen gas to the polymerization system, the molar fraction of hydrogen gas is preferably 0 mol% or higher and 100 mol% or lower, more preferably 0 mol% or higher and 80 mol% or lower, and further preferably 0 mol% or higher and 60 mol% or lower.

[0188] Furthermore, in the polymerization of the polyethylene powder of the present embodiment, in the case of using continuous two-step polymerization, it is preferred that the polymerization reaction of the second step be performed rapidly. The polymerization rate of the polyethylene can be controlled by increasing the amount of the above-described cocatalyst, increasing the polymerization pressure, etc.

[0189] In the polymerization of the polyethylene powder of the present embodiment, in the case of using continuous parallel polymerization in which polymerization reactions are performed in parallel in two reactors different in reaction conditions and they are mixed, it is preferred that a low molecular weight polyethylene having a large particle diameter be polymerized in one polymerization reactor, and a high molecular weight polyethylene having a small particle diameter be polymerized in the other reactor. The particle diameter of the polyethylene can be controlled by the polymerization pressure, the amount of the catalyst to be added, etc.

[0190] Further, in the polymerization of the polyethylene powder of the present embodiment, when the continuous parallel polymerization is used, it is preferable to make the polymerization reaction fast in the polymerization of the high molecular weight polyethylene having a small particle diameter.

[0191] In the polymerization of the polyethylene powder of the present embodiment, in order to suppress the adhesion of the polymer on the polymerization reactor, an antistatic agent such as Stadis 450 manufactured by The Associated Octel Company (distributor: Maruzen Petrochemicals Co., Ltd.) can also be used. The Stadis 450 can also be diluted in an inert hydrocarbon medium by a pump or the like and added to the polymerization reactor. As for the amount of the antistatic agent such as Stadis 450 to be added at this time, it is preferable to add in a range of 0.10 ppm or more and 20 ppm or less, and more preferably in a range of 0.20 ppm or more and 10 ppm or less, with respect to the production amount of the polyethylene per unit time.

[0192] In the production of the polyethylene powder of the present embodiment, the polyethylene powder is separated from the solvent. As the solvent separation method, for example, decantation, centrifugal separation, filter filtration, and the like can be listed, and from the viewpoint of the high separation efficiency of the polyethylene powder from the solvent, the centrifugal separation is preferable.

[0193] In the production of the polyethylene powder of the present embodiment, the deactivation of the catalyst used after the manufacturing process is performed. The method of deactivating the catalyst is not particularly limited, and it is preferable to deactivate it after the separation of the polyethylene powder from the solvent. By introducing a chemical reagent for deactivating the catalyst after the separation from the solvent, the precipitation of the catalyst components and the like dissolved in the solvent can be suppressed. As the chemical reagent for deactivating the catalyst system, for example, oxygen, water, alcohols, diols, phenols, carbon monoxide, carbon dioxide, ethers, carbonyl compounds, acetylenic compounds, and the like can be listed, but are not limited thereto.

[0194] In the production of the polyethylene powder of the present embodiment, it is preferable to perform the drying treatment after the separation of the solvent.

[0195] The drying temperature is preferably 70°C or higher and 120°C or lower, more preferably 75°C or higher and 115°C or lower, and further preferably 80°C or higher and 110°C or lower.

[0196] By the drying temperature being 70°C or higher, there is a tendency that efficient drying can be performed. By the drying temperature being 120°C or lower, there is a tendency that the drying can be performed in a state where the agglomeration and thermal degradation of the polyethylene powder are suppressed.

[0197] In the production of the polyethylene powder of the present embodiment, it is preferable to perform the cooling treatment while stirring immediately after the drying treatment.

[0198] The cooling temperature is 0°C or lower, and more preferably -10°C or lower. By the cooling temperature being 0°C or lower, the tendency of the polyethylene powder of the present embodiment to exhibit a structure unique to the polyethylene powder, in which the surface unevenness of the particles becomes rougher as the particle diameter of the powder becomes smaller, is more pronounced.

[0199] The polyethylene powder of the present embodiment can be directly charged into various molding machines to perform molding processing, or can be charged into various molding processing machines after mixing an organic peroxide in the polyethylene powder.

[0200] [Organic Peroxide]

[0201] As the organic peroxide (organic peroxide crosslinking agent) that can be used when the polyethylene powder of the present embodiment is molded, there is no particular limitation as long as it is an organic substance that contributes to the crosslinking of the above-described polyethylene and has an atomic group -O-O- within the molecule, and for example, organic peroxides such as dialkyl peroxide, diacyl peroxide, hydroperoxide, ketone peroxide, and the like; organic peroxides such as alkyl peracid ester; and the like can be exemplified. As the above-described organic peroxide, there is no particular limitation, and specifically, for example, dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl 4,4-di(t-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butyl perbenzoate, t-butyl peroxymaleate, t-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauryl peroxide, t-butyl cumyl peroxide, α,α’-di(t-butylperoxy)diisopropylbenzene, and the like can be exemplified. Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (trade name “Perhexa 25B” manufactured by NOF Corporation), 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne (trade name “Perhexyne 25B” manufactured by NOF Corporation), dicumyl peroxide, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane are preferable.

[0202] [Other Components]

[0203] Further, the polyethylene powder of the present embodiment can be used in combination with various known additives as needed. As the heat stabilizer, there is no particular limitation, and for example, tetra[methylene (3, 5-di-tert-butyl-4-hydroxy)hydrocinnamate]methane, distearyl thiodipropionate, or the like can be exemplified. As the weather resistant stabilizer, for example, bis (2, 2', 6, 6'-tetramethyl-4-piperidyl) sebacate, 2- (2-hydroxy-3-tert-butyl-5-methylphenyl) -5-chlorobenzotriazole, or the like can be exemplified. As examples of other additives, for example, a neutralizing agent or the like can be exemplified. The neutralizing agent can be used as a trapping agent for chlorine contained in the polyethylene powder or a molding processing aid or the like. As the neutralizing agent, there is no particular limitation, and for example, a stearate of an alkaline earth metal such as calcium, magnesium, barium, or the like can be exemplified.

[0204] The content of the additive contained in the polyethylene powder of the present embodiment can be found by extracting the additive in the polyethylene powder by Soxhlet extraction using tetrahydrofuran (THF) for 6 hours, separating the extract by liquid chromatography, and quantifying.

[0205] In the polyethylene powder of the present embodiment, polyethylene having different intrinsic viscosity, molecular weight distribution, or the like can be mixed, and low-density polyethylene, linear low-density polyethylene, polypropylene, polystyrene, or other resins can be mixed.

[0206] [Shaped body]

[0207] The shaped body of the present embodiment is a shaped body of the above-described polyethylene powder of the present embodiment.

[0208] In addition, the shaped body of the present embodiment can be obtained by molding a raw material containing the above-described polyethylene powder by various methods.

[0209] As the molding method of the shaped body of the present embodiment, there is no particular limitation, and for example, press molding or extrusion molding can be exemplified. Press molding is a method in which a raw material containing a polyethylene powder is uniformly spread in a mold, molding is performed by heating and pressurizing, and then cooling and taking out. The press-molded body can be used directly as a product, or can be finished into a final product by secondary processing such as cutting processing, slicing processing, or the like. On the other hand, in extrusion molding, a screw extruder or a plunger extruder in which a piston is moved forward and backward to perform extrusion is preferably used. By changing the shape of the extruder outlet, various shaped bodies such as a flat plate, a profiled product, a pipe, or the like can be obtained. In addition, a block-shaped body such as a round bar, a prism, or the like can be finished into a final product by secondary processing such as cutting processing, slicing processing, or the like.

[0210] [Use]

[0211] The molded body of the polyethylene powder of the present embodiment is not particularly limited and can be used as a liner material for ships, frames, farm implements, hoppers, silos; pipes for transporting ores; gears and bearings for machines; rollers for transporting food; guide rails; backing materials for skis; artificial bones and artificial joints; and the like for various uses.

[0212] In addition, the polyethylene powder of the present embodiment can also be used as a microporous membrane, a separator for lithium ion secondary batteries or lead storage batteries, a raw material for high-strength fibers, and the like by a wet molding method using a solvent.

[0213] [Examples]

[0214] The present embodiment will be described in more detail below by citing specific examples and comparative examples, but the present application is not limited in any way by the examples and comparative examples below.

[0215] Note that ethylene and hexane used in the examples and comparative examples were dehydrated using MS-3A (manufactured by Showa Denko K.K.), and then the hexane was further deoxygenated by reduced pressure degassing using a vacuum pump, and then used as it was.

[0216] [Measurement methods and conditions]

[0217] The physical properties of the polyethylene powder of the examples and comparative examples were measured by the following methods.

[0218] (1) Viscous average molecular weight Mv

[0219] The viscous average molecular weight Mv of the polyethylene powder obtained in the examples and comparative examples was respectively calculated in accordance with ISO 1628-3 (2010) by the following method.

[0220] First, 20 mg of the polyethylene powder was respectively weighed in a dissolution tube, the dissolution tube was replaced with nitrogen, and then 20 mL of decalin (1 g / L of 2,6-di-tert-butyl-4-methylphenol was added) was added, and the polyethylene powder was dissolved by stirring at 150°C for 2 hours, thereby respectively preparing a sample solution.

[0221] The sample solution obtained was respectively measured for the falling time (ts) between the marks in a constant-temperature bath at 135°C using a Cannon-Fenske viscometer (manufactured by Shibata Scientific Technology Ltd.: product model No. -100).

[0222] Similarly, sample solutions in which the amount of the polyethylene powder was changed to 10 mg, 5 mg, and 2 mg were respectively prepared, and the falling time (ts) between the marks was respectively measured under the same conditions.

[0223] A sample solution to which no polyethylene powder was added but only decalin was added as a blank was prepared, and the falling time (tb) was measured under the same conditions.

[0224] The specific viscosity (ηsp / C) of the polyethylene powder was calculated from the following equation.

[0225] ηsp / C = (ts / tb - 1) / 0.1 (unit: dL / g)

[0226] Next, the relationship between the concentration (C) (unit: g / dL) and the specific viscosity (ηsp / C) of the polyethylene powder was plotted, an approximate straight line equation was derived by the least square method, and extrapolated to the concentration 0, and thus the intrinsic viscosity ([η]) was calculated.

[0227] Then, the viscosity average molecular weight Mv (g / mole) was calculated from the above intrinsic viscosity [η] value using the following (Mathematical Formula A).

[0228] Mv = (5.34 x 10 4 ) x [η] 1.49 (Mathematical Formula A)

[0229] (2) Viscosity Average Molecular Weight Mv 75 and the difference ΔMv 150 between the viscosity average molecular weight Mv

[0230] Each polyethylene powder was classified using a sieve having a mesh size of 150 μm and 75 μm according to the JIS Z8801 standard, and the powder passing through the 150 μm sieve and the powder not passing through the 75 μm sieve were collected, respectively. The viscosity average molecular weight (Mv 150 ) of the powder passing through the 150 μm sieve and the viscosity average molecular weight (Mv 75 ) of the powder not passing through the 75 μm sieve were measured according to the above measuring method (1), respectively. The difference ΔMv (g / mole) (= Mv 75 - Mv 150 ) was calculated from the obtained viscosity average molecular weights, respectively.

[0231] (3) Content of Comonomer

[0232] The comonomer content (mole %) of each polyethylene powder obtained in the examples and comparative examples was measured using 13 C-NMR under the following conditions.

[0233] Apparatus: AVANCE III 500 HD Prodigy (manufactured by Bruker Biospin)

[0234] Observation frequency: 125.77 MHz 13 (C)

[0235] Pulse width: 5.0 μsec

[0236] Pulse repetition time: 5 seconds

[0237] Number of accumulations: 10,000 times

[0238] Measurement temperature: 120°C

[0239] Reference: 29.9 ppm (PE: Sδδ)

[0240] Solvent: o-C6D4Cl2

[0241] Sample concentration: 0.1 g / mL

[0242] Sample tube: 5 mm φ

[0243] Note that, as the measurement sample, a sample obtained by adding 0.6 mL of o-C6D4Cl2to 60 mg of polyethylene powder and dissolving it while heating at 130°C was used.

[0244] (4) Average particle diameter X 50

[0245] In a 200 mL plastic cup, 100 g of polyethylene powder was measured out, 1 g of carbon black was added, and the mixture was stirred well using a medicine spoon. When the stirred polyethylene powder was classified using sieves having mesh sizes of 300 μm, 212 μm, 150 μm, 106 μm, 75 μm, and 53 μm according to the JIS Z 8801 standard, the mass of the polyethylene powder remaining on each sieve was integrated from the side of the smaller mesh size, and the particle diameter at which 50% by mass was reached in the obtained integrated curve (cumulative distribution on the sieve) was taken as the average particle diameter (μm).

[0246] (5) Bulk density a, tap density b, ratio a / b

[0247] The bulk density a (g / cm3) and the tap density b (g / cm3) were measured using a powder tester PT-X (manufactured by Hosokawa Micron Corporation) as shown below. 3 ) and the tap density b (g / cm 3 ) were measured using a powder tester PT-X (manufactured by Hosokawa Micron Corporation) as shown below.

[0248] In a 100 cm 3 stainless steel cylindrical container, polyethylene powder was made to flow down by vibrating the sample supply device until the polyethylene powder accumulated in the container, the excess polyethylene powder on the container was wiped off using a spatula, and a measurement sample was prepared, and the value obtained by measuring this measurement sample was taken as the bulk density a (g / cm 3 ).

[0249] In addition, 100 cm 3 The lid of the cylindrical container was capped, and the polyethylene powder was made to flow down by vibrating the sample supply device, and was vibrated under conditions of a stroke length (tapping height) of 18 mm, a tapping speed of 60 times / minute, and a number of taps of 180 times, respectively. Then, the polyethylene powder on the container was wiped off using a spatula, and thus a measurement sample was produced, respectively, and the value obtained by measuring the measurement sample was used as the tapped density b (g / cm 3 ).

[0250] Then, the value obtained by dividing the value of the bulk density a measured as described above by the tapped density b was multiplied by 100, and thus the value of the ratio a / b was obtained.

[0251] (6) Unmelted residue in the central portion of the cross section of the extrusion-molded product

[0252] The molding of the molded product of each polyethylene powder was performed using a single-screw extruder having a screw diameter of 25 mm and an L (screw length) / D (screw diameter) of 28. A full-thread type screw was used for the screw, and the molding was performed at a barrel temperature of 210°C. A die having a length of 600 mm was provided at the front end of the extruder, and a 35 mm square molded product was molded. Note that the molding was performed under conditions of a front-stage temperature of 180°C and a rear-stage temperature of 40°C. In addition, the screw rotation speed was adjusted so that the discharge amount was 4 m / hour. The unmelted residue in the central portion of the cross section of the molded product produced was visually determined, that is, whether or not there was an unmelted portion. Note that in the case where the unmelted residue was generated, it could be discriminated from the white turbidity in the central portion. The determination criteria are shown below.

[0253] O... There was no unmelted residue in the central portion of the cross section

[0254] X... There was unmelted residue in the central portion of the cross section

[0255] (7) Impact strength of the central portion and the end portion of the extrusion-molded product

[0256] A test piece of 120 mm x 15 mm x 10 mm was cut from the central portion and the inner portion 3 mm from the end portion of each extrusion-molded product obtained by the above-described method, respectively, and the impact strength was measured by a simply supported beam impact test according to ISO 11542-2, respectively. Five test pieces were produced, and the average value of the five measurements was calculated. The ratio of the impact strength of the central portion to the impact strength of the end portion of the extrusion-molded product was obtained by dividing the average value of the impact strength of the central portion by the average value of the impact strength of the end portion (average value of the impact strength of the central portion / average value of the impact strength of the end portion), and was determined according to the following determination criteria.

[0257] O... The ratio of the impact strength of the central portion to the impact strength of the end portion of the extrusion-molded product was 0.9 or more

[0258] ○ ... The ratio of the impact strength of the center portion to the end portion of the extruded article is greater than or equal to 0.8 and less than 0.9

[0259] ×……The ratio of the impact strength of the center and end portions of the extruded article is less than 0.8

[0260] (8) Voids in the Pressed Forming

[0261] 9 kg of each polyethylene powder was naturally dropped into a 300 mm square, 100 mm high mold in a heated press molding machine. The surface was then evenly flattened and compression molded at a set temperature of 210°C and a gauge pressure of 10 MPa for 3 hours. The molded bodies were then cooled while heating was stopped while maintaining the pressure. The resulting molded bodies were cut at 100 mm intervals, and three cross sections were observed using a 5x magnifying glass. The number of void defects in the cross sections of the molded bodies was counted and evaluated according to the following criteria.

[0262] ◎……The total number of white spots on the three sections is 0

[0263] 0……The total number of white spots in 3 sections is 1

[0264] ×…The total number of white spots on the three cross sections is 2 or more

[0265] [Catalyst Synthesis Method]

[0266] [Preparation of solid catalyst component [A]]

[0267] (1) Synthesis of raw material (a-1)

[0268] 1 mol / L of Mg6(C4H9) was added to an 8L stainless steel autoclave that had been fully purged with nitrogen. 12 To 2,000 mL of a hexane solution of Al(C2H5)3 (equivalent to 2,000 mmol based on magnesium and aluminum), 146 mL of a 5.47 mol / L n-butanol hexane solution was added dropwise over 3 hours while stirring at 50°C. Afterward, the line was rinsed with 300 mL of hexane. Stirring was continued at 50°C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature and used as raw material [a-1]. The combined magnesium and aluminum concentration of raw material [a-1] was 0.704 mol / L.

[0269] (2) Synthesis of raw material [a-2]

[0270] 1 mol / L of Mg6(C4H9) was added to an 8L stainless steel autoclave that had been fully purged with nitrogen. 12A hexane solution of Al(C2H5)3, 2,000 mL (equivalent to 2000 millimoles in terms of magnesium and aluminum), was pressurized with a hexane solution of methylhydrogenpolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.) 240 mL at 8.33 moles / L while stirring at 80°C, and stirring was continued at 80°C for 2 hours. After the reaction was completed, the substance cooled to ordinary temperature was used as the starting material [a-2]. The starting material [a-2] was 0.786 moles / L in terms of the total concentration of magnesium and aluminum.

[0271] (3) Synthesis of the support [A-1]

[0272] A 1 mole / L hexane solution of hydroxytrichlorosilane, 1,000 mL, was charged into an 8L stainless autoclave after sufficient nitrogen substitution, and a hexane solution of the organic magnesium compound of the starting material [a-1], 1340 mL (equivalent to 943 millimoles of magnesium), was added dropwise over 3 hours at 65°C, and the reaction was continued while stirring at 65°C for 1 hour. After the reaction was completed, the supernatant was removed, and washing with 1,800 mL of hexane was performed 4 times, thereby obtaining the support [A-1]. The support was analyzed, and the result was that the magnesium contained in each 1 g of the solid was 7.5 millimoles.

[0273] (4) Preparation of the solid catalyst component [A]

[0274] A hexane slurry of 1,970 mL containing 110 g of the above-mentioned [A-1] support was added with a hexane solution of 1 mole / L titanium tetrachloride, 103 mL, and the starting material [a-2], 131 mL, simultaneously over 3 hours while stirring at 10°C. After the addition, the reaction was continued at 10°C for 1 hour. After the reaction was completed, the supernatant was removed, and washing with hexane was performed 4 times, thereby removing the unreacted starting material component, and the solid catalyst component [A] was prepared.

[0275] [Manufacture of polyethylene powder]

[0276] (Example 1)

[0277] Polyethylene powder was manufactured by two-step polymerization. First, in order to manufacture a low molecular weight component in the first step polymerization, hexane, ethylene, hydrogen, and a catalyst were continuously supplied to a container-type 300L polymerization reactor (1) with a stirring device. The polymerization pressure was maintained at 0.31 MPa. The polymerization temperature was maintained at 70°C by jacket cooling. Hexane was supplied from the bottom of the polymerization reactor (1) at 40 L / hour. The solid catalyst component [A] was used as the catalyst, and Mg6(C4H9) 12Al(C2H5)3as a cocatalyst. The solid catalyst component [A] was added at a rate of 1.5 g / hour from the middle of the liquid surface and the bottom of the polymerization reactor (1), and the cocatalyst was added at a rate of 10 mmol / hour from the middle of the liquid surface and the bottom of the polymerization reactor (1). Hydrogen was used as a molecular weight modifier, and was supplied at a gas phase molar concentration of hydrogen relative to the sum of ethylene and hydrogen (hydrogen / (ethylene + hydrogen)) of 4.32 mol%. Note that the hydrogen was supplied to the gas phase portion, and the ethylene was supplied from the bottom of the polymerization reactor (1).

[0278] Next, in order to produce a high molecular weight component in the second step polymerization, the polymer slurry solution in the first step polymerization reactor (1) was introduced into a flash tank with an internal volume of 300 L maintained at a pressure of 0.05 MPa and a temperature of 70°C, and unreacted ethylene and hydrogen were separated, and then introduced into the bottom of the second step vessel-type 300 L polymerization reactor (2) which was the same as the polymerization reactor (1) using a slurry pump. Hexane was introduced into the slurry pump at a rate of 110 L / hour. In addition, ethylene and a cocatalyst were continuously supplied to the polymerization reactor (2), and polymerization was performed. The polymerization pressure was maintained at 0.99 MPa, and the polymerization temperature was maintained at 73°C. The cocatalyst Mg6(C4H9) 12 Al(C2H5)3was added to the polymerization reactor (2) at a rate of 50 mmol / hour. Note that the ethylene and the cocatalyst were supplied from the same position as the polymerization reactor (1). In addition, hydrogen was not supplied during this second step polymerization. The high molecular weight polymerization was performed in such a way that the ratio of the mass of the high molecular weight component produced in the second step polymerization reactor (2) to the sum of the mass of the low molecular weight component produced in the first step polymerization reactor (1) and the mass of the high molecular weight component produced in the second step polymerization reactor (2) (mass of the high molecular weight component produced in the second step polymerization reactor (2) / (mass of the low molecular weight component produced in the first step polymerization reactor (1) + mass of the high molecular weight component produced in the second step polymerization reactor (2)) was 0.50. The production rate of the polyethylene in the polymerization reactor (2) was 20 kg / hour.

[0279] The resulting polymerization slurry was continuously withdrawn to a flash tank at a pressure of 0.04 MPa in such a way that the liquid level of the polymerization reactor (2) was maintained constant, and unreacted ethylene was separated.

[0280] Then, the resulting polymerization slurry was continuously fed to a centrifugal separator in such a way that the liquid level of the polymerization reactor (2) was maintained constant, and the polymer (polyethylene powder) was separated from the solvent and the like.

[0281] The separated polyethylene powder was stirred and dried at 110°C for 0.5 hours while nitrogen was sprayed. Note that in this drying process, steam was sprayed to the polyethylene powder after polymerization, and thereby the deactivation of the catalyst and the cocatalyst was performed. Then, the polyethylene powder after drying was stirred while nitrogen was sprayed at -10°C for 10 minutes, and thereby the polyethylene powder was cooled. After the cooling, 500 ppm of calcium stearate (manufactured by Otsuka Chemical Co., Ltd., C60) was added to the polyethylene powder after returning to normal temperature, and uniformly mixed using a Henschel mixer. Next, the polyethylene powder was passed through a sieve having a mesh size of 425 μm, and the powder not passed through the sieve was removed, and thereby the polyethylene powder of Example 1 having a viscosity average molecular weight Mv of 193 x 10 4 g / mole was obtained.

[0282] The properties of the obtained polyethylene powder of Example 1 are shown in Table 1.

[0283] (Example 2)

[0284] The polyethylene powder was produced by two-step polymerization in the same manner as in Example 1. In the first step polymerization, 1-butene was continuously supplied from the bottom of the polymerization reactor (1) at 0.90 mole% of 1-butene with respect to ethylene, the gas phase mole concentration of hydrogen with respect to the sum of ethylene and hydrogen was changed to 1.40 mole%, 1-butene was stopped to be supplied in the second step polymerization, the concentration of 1-butene with respect to ethylene was 0.07 mole%, the polymerization pressure was changed to 1.95 MPa, the polymerization temperature was changed to 60°C, and otherwise, the polyethylene powder of Example 2 having a viscosity average molecular weight Mv of 407 x 10 4 g / mole and a comonomer content of 0.04 mole% was obtained by the same operation as in Example 1. The production rate of the polyethylene in the polymerization reactor (2) was 20 kg / hour.

[0285] The properties of the obtained polyethylene powder of Example 2 are shown in Table 1.

[0286] (Example 3)

[0287] Polyethylene powder was produced by parallel polymerization. Hexane, ethylene, 1-butene, hydrogen, and catalyst were continuously supplied from the same positions as in Example 1 above to a 300-L reactor (1) of the same type of vessel as in Example 1 above. The polymerization pressure was maintained at 0.30 MPa, and the polymerization temperature was maintained at 78°C. The flow rate of hexane was changed to 80 L / hour, the supply amount of the solid catalyst component [A] was changed to 0.4 g / hour, the cocatalyst was changed to a mixture of triisobutylaluminum and diisobutylaluminum hydride (a mixture of 9:1 by mass, in that order) at 5 mmol / hour, the gas-phase molar concentration of hydrogen was changed to 0.50 mol%, and the concentration of 1-butene was changed to 0.46 mol% relative to ethylene, and otherwise the polymerization reaction in the polymerization reactor (1) was carried out in the same manner as in Example 1 above. The production rate of polyethylene in the polymerization reactor (1) was 10 kg / hour.

[0288] At the same time as the polymerization in the polymerization reactor (1), a polymerization reaction was also carried out in a 300-L polymerization reactor (2) of the same type of vessel as the polymerization reactor (1). Hexane, ethylene, 1-butene, and catalyst were continuously supplied from the same positions as in Example 2 above. Note that hydrogen was not added. The polymerization pressure was maintained at 1.23 MPa, and the polymerization temperature was maintained at 60°C. The flow rate of hexane was changed to 80 L / hour, the supply amount of the solid catalyst component [A] was changed to 1.4 g / hour, the cocatalyst was changed to Mg6(C4H9) 12 Al(C2H5)3 at 50 mmol / hour, and the concentration of 1-butene was changed to 0.46 mol% relative to ethylene, and otherwise the polymerization reaction in the polymerization reactor (2) was carried out in the same manner as in Example 2 above. The production rate of polyethylene in the polymerization reactor (2) was 10 kg / hour.

[0289] The polymerization slurry of the polymerization reactor (1) and the polymerization reactor (2) was continuously introduced into a 300-L internal volume stirrer with a pressure of 0.04 MPa in such a manner that the liquid level of the polymerization reactor was kept constant, and the polymerization slurry was stirred while separating out unreacted ethylene and hydrogen. Then, the polyethylene powder of Example 3 with a viscosity average molecular weight Mv of 415 x 10 4 g / mol and a comonomer content of 0.04 mol% was obtained by the same operation as in Example 1 above. The production rate of polyethylene in the polymerization reactor (1) and the polymerization reactor (2) was 20 kg / hour in total.

[0290] The properties of the obtained polyethylene powder of Example 3 are shown in Table 1.

[0291] (Example 4)

[0292] Polyethylene powder was produced by parallel polymerization in the same manner as in Example 3. Polymerization reaction in the polymerization reactor (1) was conducted in the same manner as in Example 3, except that the polymerization pressure in the polymerization reactor (1) was changed to 0.31 MPa, the supply rate of the solid catalyst component [A] was changed to 0.3 g / hour, the supply rate of the cocatalyst was changed to 4 mmol / hour, the gas phase molar concentration of hydrogen was changed to 0.64 mol%, and 1-butene was not added. The production rate of polyethylene in the polymerization reactor (1) was 5 kg / hour.

[0293] A polymerization reaction was carried out in the polymerization reactor (2) in the same manner as in Example 3, except that the polymerization pressure in the polymerization reactor (2) was changed to 2.30 MPa, the polymerization temperature was changed to 50°C, the supply rate of the solid catalyst component [A] was changed to 1.1 g / hour, and the concentration of 1-butene was changed to 0.60 mol%. The production rate of polyethylene in the polymerization reactor (2) was 10 kg / hour.

[0294] Then, the viscosity average molecular weight Mv of 630×10 4 g / mol and a comonomer content of 0.03 mol% of the polyethylene powder of Example 4. The production rate of polyethylene in the polymerization reactor (1) and the polymerization reactor (2) was 15 kg / hour in total.

[0295] Table 1 shows the properties of the polyethylene powder obtained in Example 4.

[0296] (Example 5)

[0297] Polyethylene powder was produced by two-step polymerization in the same manner as in Example 2. Polymerization reactions were carried out in polymerization reactors (1) and (2) in the same manner as in Example 2, except that the polymerization pressure in the second-step polymerization was changed to 0.65 MPa and the co-catalyst supply rate was changed to 10 mmol / h.

[0298] Then, the viscosity average molecular weight Mv of 404×10 4 g / mol and a comonomer content of 0.03 mol% of the polyethylene powder of Example 5. The production rate of polyethylene in the polymerization reactor (2) was 20 kg / hour.

[0299] Table 1 shows the properties of the polyethylene powder obtained in Example 5.

[0300] (Example 6)

[0301] Polyethylene powder was produced by two-step polymerization in the same manner as in Example 2.

[0302] After the polymerization in the polymerization reactor (1) and the polymerization reactor (2) was performed, spraying of nitrogen gas at -10°C for 10 minutes to the dried powder was omitted, and otherwise, the same operation as in Example 2 was performed.

[0303] Then, the same operation as in Example 2 was performed to obtain the polyethylene powder of Example 6 having a viscosity average molecular weight Mv of 403 x 10 4 g / mole and a comonomer content of 0.04 mol%. The production rate of the polyethylene in the polymerization reactor (2) was 20 kg / hour.

[0304] The properties of the obtained polyethylene powder of Example 6 are shown in Table 1.

[0305] (Comparative Example 1)

[0306] The polyethylene powder was produced by one-step polymerization. To the same vessel type 300 L polymerization reactor (1) as in Example 1, hexane, ethylene, hydrogen and the catalyst were continuously supplied from the same positions as in Example 1. The polymerization pressure was maintained at 0.30 MPa, and the polymerization temperature was maintained at 75°C. The flow rate of hexane was changed to 80 L / hour, the supply amount of the solid catalyst component [A] was changed to 0.3 g / hour, the mixture of triisobutylaluminum and diisobutylaluminum hydride as the cocatalyst (mixture in the mass ratio of 9: 1 in this order) was changed to 5 mmol / hour, the gas phase molar concentration of hydrogen was changed to 0.27 mol%, and otherwise, the same operation as in Example 1 was performed for the polymerization in the polymerization reactor (1). The production rate of the polyethylene in the polymerization reactor (1) was 10 kg / hour.

[0307] Then, the same operation as in Example 1 was performed to obtain the polyethylene powder of Comparative Example 1 having a viscosity average molecular weight Mv of 330 x 10 4 g / mole, except that spraying of nitrogen gas at -10°C for 10 minutes to the dried powder was not performed.

[0308] The properties of the obtained polyethylene powder of Comparative Example 1 are shown in Table 1.

[0309] (Comparative Example 2)

[0310] The polyethylene powder was produced by two-step polymerization, the same as in Example 2. The polymerization pressure at the second step polymerization was changed to 0.65 MPa, the supply amount of the cocatalyst was changed to 10 mmol / hour, spraying of nitrogen gas at -10°C for 10 minutes to the dried powder was not performed, and otherwise, the same operation as in Example 2 was performed to obtain the polyethylene powder of Comparative Example 2 having a viscosity average molecular weight Mv of 411 x 10 4Comparative Example 2 polyethylene powder having a viscosity average molecular weight Mv of 393 x 104g / mole and a comonomer content of 0.04 mol%. The production rate of the polyethylene in the polymerization reactor (2) was 20 kg / hour.

[0311] The properties of the obtained Comparative Example 2 polyethylene powder are shown in Table 1.

[0312] (Comparative Example 3)

[0313] Comparative Example 3 polyethylene powder having a viscosity average molecular weight Mv of 393 x 104g / mole and a comonomer content of 0.05 mol%. The production rate of the polyethylene in the polymerization reactor (2) was 20 kg / hour. 4

[0314] The properties of the obtained Comparative Example 3 polyethylene powder are shown in Table 1.

[0315] (Comparative Example 4)

[0316] Comparative Example 4 polyethylene powder having a viscosity average molecular weight Mv of 391 x 104g / mole and a comonomer content of 0.06 mol%. The production rate of the polyethylene in the polymerization reactor (2) was 20 kg / hour. 4

[0317] ​​The properties of the obtained polyethylene powder of Comparative Example 4 are shown in Table 1.

[0318]

[0319] Industrial applicability

[0320] The polyethylene powder of the present application has industrial applicability as a raw material for various molded bodies, microporous membranes, separators, high-strength fibers.

Claims

1. A polyethylene powder, wherein The polyethylene powder has a viscosity average molecular weight Mv of 100,000 g / mole to 10,000,000 g / mole, The polyethylene powder has an average particle size X of 50 μm to 200 μm based on cumulative mass. 50 , The viscosity average molecular weight Mv of the powder under the sieve when the polyethylene powder is classified using a sieve with a mesh size of 75 μm 75 The viscosity average molecular weight Mv of the powder on the sieve when the polyethylene powder is classified using a sieve with a mesh size of 150 μm 150 The difference ΔMv is greater than 0 g / mole and less than or equal to 4,000,000 g / mole, where ΔMv=Mv 75 -Mv 150 , Mv 75 and Mv 150 The unit of is g / mole, and The ratio a / b of the bulk density a of the polyethylene powder to the tap density b is 83.0% or more, and the units of the bulk density a and the tap density b are both g / cm 3 , The viscosity average molecular weight is determined according to ISO 1628-3 (2010); The bulk density refers to the apparent density of polyethylene powder when it is allowed to fall freely, and the tap density refers to the apparent density after the free-falling powder is tapped 180 times. The bulk density a and the tap density b are measured by the following method: At 100cm 3 In a cylindrical container, the sample supply device is vibrated to cause the polyethylene powder to flow down until the polyethylene powder accumulates in the container. The excess polyethylene powder on the container is scraped off with a scraper to prepare a measurement sample. The value obtained by measuring the measurement sample is used as the bulk density a. At 100cm 3 The cylindrical container was covered with a lid, and the polyethylene powder was allowed to flow down separately by vibrating the sample supply device. The containers were vibrated under the conditions of a stroke length of 18 mm, a vibration speed of 60 times / min, and a vibration number of 180 times. Then, excess polyethylene powder on the container was wiped off with a scraper to prepare measurement samples. The values ​​obtained by measuring the measurement samples were used as the tap density b.

2. The polyethylene powder according to claim 1, wherein The polyethylene powder has a viscosity average molecular weight Mv of 500,000 g / mol or more and 9,000,000 g / mol or less.

3. The polyethylene powder according to claim 1 or 2, wherein The polyethylene powder has a viscosity average molecular weight Mv of 1,000,000 g / mol or more and 8,000,000 g / mol or less.

4. The polyethylene powder according to claim 1 or 2, wherein The average particle size X of the polyethylene powder 50 60μm~175μm.

5. The polyethylene powder according to claim 1 or 2, wherein The average particle size X of the polyethylene powder 50 70μm~150μm.

6. The polyethylene powder according to claim 1 or 2, wherein The ratio a / b is greater than 86.0%.

7. The polyethylene powder according to claim 1 or 2, wherein The ratio a / b is greater than 88.0%.

8. The polyethylene powder according to claim 1 or 2, wherein The ratio a / b is 100% or less.

9. The polyethylene powder according to claim 1 or 2, wherein The difference ΔMv is greater than 5 g / mole and less than or equal to 3,500,000 g / mole.

10. The polyethylene powder according to claim 1 or 2, wherein The difference ΔMv is greater than 10 g / mole and less than or equal to 3,000,000 g / mole.

11. The polyethylene powder according to claim 1 or 2, wherein The difference ΔMv is greater than 60 g / mole and less than or equal to 3,000,000 g / mole.

12. The polyethylene powder according to claim 1 or 2, wherein The polyethylene constituting the polyethylene powder is an ethylene homopolymer or a copolymer of ethylene and other comonomers.

13. The polyethylene powder according to claim 12, wherein The other comonomers are one or more selected from α-olefins, vinyl compounds and non-conjugated polyenes.

14. The polyethylene powder according to claim 13, wherein The α-olefin is an α-olefin having 3 to 20 carbon atoms.

15. The polyethylene powder according to claim 14, wherein The α-olefin having 3 to 20 carbon atoms is selected from propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene and 1-tetradecene.

16. The polyethylene powder according to claim 12, wherein The copolymer of ethylene and other comonomers is an ethylene-1-butene copolymer or an ethylene-propylene copolymer.

17. The polyethylene powder according to claim 13, wherein The vinyl compound is selected from vinylcyclohexane and styrene.

18. The polyethylene powder according to claim 13, wherein The non-conjugated polyene is selected from 1,5-hexadiene and 1,7-octadiene.

19. The polyethylene powder according to claim 12, wherein The content of the other comonomer is 0.8 mol% or less based on the polyethylene.

20. The polyethylene powder according to claim 19, wherein The content of the other comonomer is 0.7 mol% or less based on the polyethylene.

21. The polyethylene powder according to claim 19 or 20, wherein The content of the other comonomer is 0.6 mol% or less based on the polyethylene.

22. The method for producing a polyethylene powder according to any one of claims 1 to 21, wherein The polyethylene powder is produced by two-step polymerization, wherein the first step polymerization yields polyethylene having a lower molecular weight than the second step polymerization, and the second step polymerization reaction is rapidly advanced.

23. The method for producing a polyethylene powder according to any one of claims 1 to 21, wherein The polyethylene powder is manufactured by parallel polymerization using two polymerizers, wherein low molecular weight polyethylene with a large particle size is obtained by polymerization in one polymerizer, and high molecular weight polyethylene with a small particle size is obtained by polymerization in the other polymerizer, and when high molecular weight polyethylene with a small particle size is obtained by polymerization, the polymerization reaction is rapidly carried out, and then the polymerization slurries are mixed.

24. A molded article, wherein The molded product is obtained by molding a raw material containing the polyethylene powder according to any one of claims 1 to 21.

25. A pressed body, wherein The press-molded body is obtained by press-molding a raw material containing the polyethylene powder according to any one of claims 1 to 21.

26. The press-formed body according to claim 25, wherein The number of void defects in the cross section of the press-formed body is one or less.

27. An extruded body, wherein: The extruded product is obtained by extruding a raw material containing the polyethylene powder according to any one of claims 1 to 21.

28. The extruded article according to claim 27, wherein The ratio of the impact strength of the central portion to the end portion of the extruded body is greater than or equal to 0.

8.

29. A microporous membrane, wherein The microporous film uses the polyethylene powder according to any one of claims 1 to 21.

30. A high-strength fiber, wherein The high-strength fiber uses the polyethylene powder according to any one of claims 1 to 21.

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