TWI846388B - Polyethylene powder and molded article using the same - Google Patents

Abstract

The present invention provides a polyethylene powder and a molded body using the same, wherein the polyethylene powder has excellent processability, an excellent production speed during molding of the molded body, and can improve the yield rate or uniformity of physical properties by suppressing the reduction in strength caused by void defects or insufficient fusion. The polyethylene powder of the present invention has a viscosity average molecular weight Mv of 100,000 (g/mol) to 10,000,000 (g/mol), an average particle size X ₅₀ of 50 μm to 200 μm based on the cumulative mass, a difference ΔMv (here, ΔMv = Mv 75 - Mv 150 ) between the viscosity average molecular weight Mv ₇₅ (g/mol) of the powder passing through the sieve when graded with a sieve with an opening of ₇₅ μm and the viscosity average molecular weight Mv ₁₅₀ (g/mol) of the powder on the sieve when graded with a sieve with an opening of ₁₅₀ μm is greater than 0 (g/mol) and is less than 4,000,000 (g/mol), and the bulk density a (g/cm ³ ) is relative to the tap density b (g/cm ³ ) ratio a/b is 83.0(%) or more.

Description

Polyethylene powder and molded body using the same

The present invention relates to a polyethylene powder and a molded body using the same.

Compared with general polyethylene, ultra-high molecular weight polyethylene powder with higher molecular weight has better wear resistance, impact resistance, self-lubricating property, chemical resistance, low temperature characteristics, dimensional stability, lightness, and food safety than other engineering plastics or metals. Therefore, the molded body is used in various fields such as ship or truck lining materials, mechanical gears or bearings, food transport rollers or ski linings, artificial bones or artificial joints, etc.

Ultra-high molecular weight polyethylene has a high molecular weight and low melt fluidity, so it is not easy to melt and knead the resin. Therefore, as a molding method, it is mostly formed by directly heating and compressing the raw material resin in powder form, by pressure molding, plunger extrusion molding, screw extrusion molding, etc. In addition, as issues in the molding of ultra-high molecular weight polyethylene, there are: slow processing speed and poor productivity, void defects or strength reduction due to poor filling of powders and insufficient fusion of powders, and the accompanying low yield rate, especially the larger the molded body, the greater the difference in physical properties between the center and the end of the molded body, etc. These problems hinder the further widespread use of ultra-high molecular weight polyethylene molded bodies.

To solve these problems, the industry is researching several methods. For example, Patent Document 1 reports that productivity can be improved by mixing ultra-high molecular weight polyethylene with a molecular weight of more than 1 million with low molecular weight polyethylene with a molecular weight of 5,000 to 20,000.

Furthermore, Patent Document 2 reports that the molecular weight distribution can be reduced by using a special cross-linked metallocene catalyst system, thereby improving processability.

Furthermore, Patent Document 3 reports that by reducing the molecular weight distribution and particle size distribution, the productivity during compression molding can be improved.

In addition, Patent Document 4 reports that by subjecting the powder to a special heat treatment, it is possible to adjust the uniquely defined powder diffusion parameters, suppress the generation of void defects, and improve the yield rate. [Prior Technical Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 57-177036 [Patent Document 2] Japanese Patent Publication No. 2009-514997 [Patent Document 3] Japanese Patent Publication No. 2017-141312 [Patent Document 4] WO2020/171017

[The problem the invention is trying to solve]

According to the method described in Patent Document 1, although the production speed during molding can be increased, the physical properties of the molded product, especially the wear resistance, are greatly reduced. In addition, the improvement of the yield rate or the unevenness of physical properties is not considered.

It is reported that according to the method described in Patent Document 2, processability can be improved by reducing the molecular weight distribution. However, no specific effect is shown, and no consideration is given to improvement in yield or uneven physical properties.

According to the report, the method described in Patent Document 3 improves processability by reducing molecular weight distribution and particle size distribution. It is speculated that there is some effect on production speed or suppression of void defects, but no specific effect is shown, and no consideration is given to improvement of yield or uneven physical properties.

According to the report, the method described in Patent Document 4 can suppress the generation of void defects and improve the yield rate. However, its performance cannot meet the requirements of thicker molded bodies. In addition, it does not consider the increase in production speed or the unevenness of physical properties.

Therefore, in view of the above problems, the present invention aims to provide a polyethylene powder and a molded body using the same, wherein the polyethylene powder has excellent processability, the production speed of the molded body is excellent, and the yield rate or uniformity of physical properties can be improved by suppressing the reduction in strength caused by void defects or insufficient fusion. [Technical means to solve the problem]

The inventors of the present invention have conducted intensive research to solve the above-mentioned problems, and surprisingly found that when polyethylene powder is classified by a screen with a specified opening, the difference in viscosity average molecular weight between powder with a larger particle size and powder with a smaller particle size, and the ratio of the specified loose density to the tapped density of the polyethylene powder can solve the above-mentioned problems, thereby completing the present invention. That is, the present invention is as follows.

[1] A polyethylene powder having a viscosity average molecular weight Mv of 100,000 (g/mol) to 10,000,000 (g/mol), an average particle size _X50 of 50 μm to 200 μm based on cumulative mass, a difference ΔMv (where ΔMv = Mv75 - Mv150) between the viscosity average molecular weight of the powder passing through the sieve when classified with a sieve with an opening of ₇₅ μm and the viscosity average molecular weight of the powder on the _sieve when classified with a sieve with an opening of _{150 μm} , is greater than 0 (g/mol) and is less than 4,000,000 (g/mol), and a bulk density a (g/ ^cm3 ) relative to a tap density b (g/ ^cm3) ) ratio a/b is 83.0(%) or more.

[2] Polyethylene powder as described in [1], wherein the above ratio a/b is greater than 88.0(%).

[3] The polyethylene powder as described in [1] or [2], wherein the difference ΔMv is greater than 10 (g/mol) and less than 3,000,000 (g/mol).

[4] A molded body, which is formed by molding a raw material comprising the polyethylene powder described in any one of [1] to [3].

[5] A pressurized molded body, which is formed by pressurizing a raw material comprising a polyethylene powder as described in any one of [1] to [3].

[6] An extruded product formed by extruding a raw material comprising a polyethylene powder as described in any one of [1] to [3]. [7] A microporous membrane using the polyethylene powder as described in any one of [1] to [3]. [8] A high-strength fiber using the polyethylene powder as described in any one of [1] to [3]. [Effect of the invention]

According to the present invention, a polyethylene powder and a molded body using the same can be provided. The memory fine powder has a specific viscosity average molecular weight difference ΔMv and a specific ratio a/b of bulk density a to tap density b, and has excellent processability. The production speed during molding of the molded body is excellent, and the yield rate and uniformity of physical properties can be improved.

The following is a detailed description of the implementation of the present invention (hereinafter referred to as "this implementation"). Furthermore, the following implementation is an example for explaining the present invention, and the present invention is not limited to the examples. That is, the present invention can be arbitrarily changed and implemented within the scope of its main purpose. Furthermore, in this specification, when "～" is used to connect the numerical values or physical property values before and after it, the values before and after it are included.

[Polyethylene powder] The polyethylene powder of the present embodiment (hereinafter also referred to as "powder") has a viscosity average molecular weight Mv of 100,000 (g/mol) to 10,000,000 (g/mol), an average particle size _X50 of 50 μm to 200 μm based on the cumulative mass, a difference ΔMv (here, ΔMv = Mv75 - Mv150) between the viscosity average molecular weight _Mv75 (g/mol) of the powder passing through the sieve when graded with a sieve with an opening of ₇₅ μm and the viscosity average molecular weight _Mv150 (g/mol) of the powder on the sieve when graded with a sieve with an opening of ₁₅₀ μm is greater than 0 (g/mol) and is less than 4,000,000 (g/mol), and a bulk density a (g/ ^cm3 ) relative to a tap density b (g/cm3) is greater than 0 (g/mol) and less than 4,000,000 (g/mol). ³ ) The ratio a/b is 83.0(%) or more.

The polyethylene powder in this embodiment refers to a collection of polyethylene particles.

The polyethylene constituting the polyethylene powder of the present embodiment is not limited to the following, and preferably includes ethylene homopolymers or copolymers of ethylene and other comonomers. The copolymers may be tertiary random copolymers.

The other comonomers are not particularly limited, and examples thereof include α-olefins and vinyl compounds.

The α-olefin is not particularly limited, and examples thereof include α-olefins having 3 to 20 carbon atoms. Specifically, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, etc. are included as the α-olefin. Among them, propylene and 1-butene are preferred from the viewpoint of the impact resistance, abrasion resistance or heat resistance, and rigidity of the molded body of the polyethylene powder.

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

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

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

The content of other comonomers is not particularly limited, but is preferably 0.8 mol% or less, more preferably 0.7 mol% or less, and further preferably 0.6 mol% or less relative to polyethylene. By adjusting the amount of other comonomers to 0.8 mol% or less, there is a tendency to easily obtain a molded body with excellent impact resistance, wear resistance, and rigidity. When other comonomers are used, the lower limit of the amount is not particularly limited, and it can be more than 0 mol% relative to polyethylene.

The content of the comonomer in the polyethylene can be confirmed by NMR (Nuclear Magnetic Resonance) or infrared analysis as described in the examples below.

[Viscosity average molecular weight Mv] The viscosity average molecular weight Mv (g/mol) of the polyethylene powder of this 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.

By making the viscosity average molecular weight Mv 100,000 (g/mol) or more, there is a tendency that the impact resistance or abrasion resistance of the molded body obtained by molding the polyethylene powder of the present embodiment is further improved. In addition, by making the viscosity average molecular weight Mv 10,000,0000 (g/mol) or less, there is a tendency that when the powder is molded, the melting of the powder or the fusion of the powders is promoted, the production speed during the molding process is further increased, the void defects caused by insufficient fusion are further suppressed, and the physical property unevenness in the molded body is further reduced.

Furthermore, the viscosity average molecular weight Mv of the polyethylene powder can be adjusted by using a catalyst described later, appropriately adjusting polymerization conditions, etc. As polymerization conditions, specifically, hydrogen is present in the polymerization system, and/or the polymerization temperature is changed. Furthermore, the viscosity average molecular weight Mv of the polyethylene powder can be obtained by the method described in the examples described later.

[Average particle size _X50 ] The average particle size _X50 of the polyethylene powder of the present embodiment refers to the particle size (sieve size) with a cumulative mass of 50 mass%, that is, the median diameter. The calculation of the average particle size _X50 of the polyethylene powder can be performed by the method described in the embodiments described below. The average particle size _X50 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 making the average particle size _X50 of the polyethylene powder less than 200 μm, the polyethylene powder is easy to melt, and as a result, there is a tendency as follows: the production speed during processing is increased, the generation of void defects caused by insufficient fusion is suppressed, and the unevenness of physical properties in the molded body is reduced. Furthermore, by setting the average particle size _X50 of the polyethylene powder to be 50 μm or more, scattering of the powder can be suppressed, and thus the workability in handling the powder tends to be improved.

The average particle size _X50 of the polyethylene powder can be controlled by screening with a screen of a specific opening. In this embodiment, from the viewpoint of solubility in a solvent, it is particularly preferred to use polyethylene powder that has passed through a screen with an opening of 425 μm in a standard screen that complies with JIS Z8801 specifications.

[Difference ΔMv] The difference ΔMv refers to the difference between the viscosity average molecular weight Mv ₇₅ of the powder passing through the sieve holes when the polyethylene powder is classified with a sieve with an opening of 75 μm (hereinafter also referred to as "sieved powder") and the viscosity average molecular weight Mv ₁₅₀ of the powder remaining on the sieve holes when the polyethylene powder is classified with a sieve with an opening of 150 μm (hereinafter also referred to as "sieved powder"). Specifically, the difference ΔMv is a value calculated based on the formula: ΔMv = Mv ₇₅ - Mv ₁₅₀ . The difference ΔMv is greater than 0 (g/mol) and less than 4,000,000 (g/mol), preferably greater than 5 (g/mol) and less than 3,500,000 (g/mol), and more preferably greater than 10 (g/mol) and less than 3,000,000 (g/mol). By making the difference ΔMv greater than 0 (g/mol), the viscosity average molecular weight Mv of the large particle size powder is made smaller than the viscosity average molecular weight Mv of the small particle size powder. As a result, there is a tendency that the melting of the large particle size powder with slower heat conduction or the fusion of the powders is easier to proceed, the production speed during the molding process is further increased, the void defects caused by insufficient fusion are further suppressed, and the non-uniformity of the physical properties in the molded body is further reduced. On the other hand, by making the difference ΔMv 4,000,000 (g/mol) or less, the viscosity average molecular weight Mv of the large particle size powder can be suppressed from being too low. As a result, there is a tendency that the impact resistance and wear resistance of the molded body are further improved. In addition, at the same time, the viscosity average molecular weight Mv of the small particle size powder can be suppressed from being too high. As a result, there is a tendency that the melting of the small particle size powder and the fusion of the powders are easy to proceed, the production speed during the molding process is further increased, the void defects caused by insufficient fusion are further suppressed, and the physical property unevenness in the molded body is further reduced.

The viscosity average molecular weight Mv ₇₅ and the viscosity average molecular weight Mv ₁₅₀ can be obtained by the method described in the examples described later, and the difference ΔMv can be calculated from these values based on the above formula.

The method for controlling the difference ΔMv to be greater than 0 (g/mol) and less than 4,000,000 (g/mol) is not particularly limited, and for example, a selective polymerization method can be cited. As a specific example, a method of using the catalyst described below in the polymerization reaction of polyethylene in two stages (hereinafter also referred to as "two-stage polymerization"); and a method of polymerizing polyethylene having a molecular weight lower than that of the second stage polymerization in the first stage of the two-stage polymerization, etc. can be cited.

The reason why the difference ΔMv can be controlled by the above method is explained. In the first stage of polymerization, low molecular weight polyethylene with a certain particle size distribution is produced. The catalyst activity of the large particle size powder after the first stage of polymerization is reduced, and the diffusion rate of ethylene in the catalyst to the center of the powder is slowed down. Therefore, when the high molecular weight polyethylene is polymerized in the second stage, the polymerization reaction is not easy to proceed. On the other hand, the catalyst activity of the small particle size powder after the first stage of polymerization is less reduced than that of the large particle size powder, and the diffusion rate of ethylene in the catalyst to the center of the powder is relatively fast. Therefore, when the high molecular weight polyethylene is polymerized in the second stage, the polymerization reaction is easy to proceed. As a result, the viscosity average molecular weight Mv of the powder after the second stage of polymerization increases as the particle size decreases. Furthermore, as a method of controlling ΔMv within a predetermined range, there are, for example, adjusting the molecular weights of the first and second stages, adjusting the particle size distribution of the first stage, and the like.

As another method for controlling the difference ΔMv to be greater than 0 (g/mol) and less than 4,000,000 (g/mol), there can be cited a method of mixing large particle size low molecular weight polyethylene and small particle size high molecular weight polyethylene obtained by the following polymerization method: the above-mentioned polymerization method is: using the catalyst described below, using two polymerizers to carry out parallel polymerization reaction, and then mixing the polymer slurries (hereinafter also referred to as "parallel polymerization"). As a method for controlling the particle size of the powder, there can be cited an example of adjusting the activity of the catalyst, and specifically, it can be cited an example of changing the polymerization pressure or the amount of catalyst added.

Furthermore, as another method for controlling the difference ΔMv to be greater than 0 (g/mol) and less than or equal to 4,000,000 (g/mol), there can be cited a method of mixing a plurality of polyethylene powders having different particle sizes and viscosity average molecular weights Mv by dry blending.

[Ratio a/b] In this specification, bulk density a means the apparent density (g/cm ³ ) of polyethylene powder when it is allowed to fall freely, and tap density b means the apparent density (g/cm ³ ) after the free-falling powder is tapped 180 times. The bulk density a and tap density b can be obtained by the method described in the embodiments described below, and the value of the ratio a/b (%) can be obtained based on these values based on the formula: ratio a/b = 100×a/b. That is, the closer the ratio a/b is to 100 (%), the denser the powder is packed in the free-fall stage. The ratio a/b is 83.0 (%) or more, preferably greater than 86.0 (%), and more preferably greater than 88.0 (%). The upper limit is not particularly limited, and it can be 100 (%) or less. By making the ratio a/b 83.0(%) or more, the powders are easily packed densely and the powders are easily fused with each other, so there is a tendency to suppress the generation of void defects during the molding process and further reduce the unevenness of physical properties in the molded body.

The method for controlling the ratio a/b to 83.0 (%) or more is not particularly limited, and examples thereof include adjusting the polymerization method, polymerization conditions, and powder cooling method.

First, specific examples of polymerization methods and polymerization conditions for controlling the ratio a/b to be 83.0 (%) or more are described. As polymerization methods, the above-mentioned two-stage polymerization or parallel polymerization can be cited. As polymerization conditions for two-stage polymerization, the second stage polymerization reaction can be made to proceed quickly. As polymerization conditions for parallel polymerization, one of the polymerizers can be used to polymerize polyethylene with a large particle size, and the other polymerizer can be used to polymerize polyethylene with a small particle size, and the polymerization reaction can be made to proceed quickly when the polyethylene with a small particle size is polymerized. As specific examples of polymerization conditions for making the polymerization reaction proceed quickly, increasing the amount of the auxiliary catalyst added, which will be described later, and increasing the polymerization pressure can be cited. By using this polymerization method and polymerization conditions to produce polyethylene powder, as the particle size decreases, the surface roughness of the powder particles increases. This unique powder morphology can improve the ratio a/b compared to the past. By forming this unique powder morphology, the contact area between the large-particle powder with smaller surface roughness and the small-particle powder with larger surface roughness decreases. During the free fall stage, the small-particle powder fills the gap between the large-particle powder more densely, thereby increasing the value of the ratio a/b. Furthermore, when the surface roughness of both the large-particle powder and the small-particle powder increases, the surface roughness of each other becomes an obstacle, which will cause the value of the ratio a/b to decrease.

Taking the two-stage polymerization of the above specific example as an example, the reason why the surface roughness of the powder particles increases as the particle size decreases by the above method is explained. As described above, the small-particle powder after the first stage polymerization is easier to undergo the second stage polymerization reaction, i.e., particle growth, than the large-particle powder, and the stress of the small-particle powder during particle growth is not easy to disperse, so the powder surface is more likely to have cracks than the large-particle powder. As a result, the surface roughness of the powder particles after the two-stage polymerization increases as the particle size decreases.

Next, as a specific example for controlling the ratio a/b to 83.0(%) or more, the cooling method of the powder is described. By rapidly cooling the powder while stirring it after drying the polymerized powder, the surface roughness of the powder particles can be increased as the particle size decreases. The reason is that small particle size powders are easy to cool, and the stress accompanying the volume shrinkage during cooling is not easy to disperse.

[Manufacturing method of polyethylene powder] [Catalyst component] The catalyst component used to manufacture the polyethylene powder of this embodiment is not particularly limited, and an example thereof may be a common Ziegler-Natta catalyst.

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

(A-1): (M ¹ ) _α (Mg) _β (R ² ) _a (R ³ ) _b (Y ¹ ) _c …… (Formula 1) (In Formula 1, 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 are alkyl groups having 2 to 20 carbon atoms, and Y ¹ is an alkoxy group, a silanyloxy group, an allyloxy group, an amino group, an amide group, -N＝CR ⁴ , R ⁵ , -SR ⁶ (Here, R ⁴ , R ⁵ and R ⁶ represent alkyl groups having 1 to 20 carbon atoms, and when c is 2, Y ¹ may be different), any one 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 the atomic valence of M ¹ )).

(A-2): Ti(OR ⁷ ) _d X ¹ _(4-d) ... (Formula 2) (In Formula 2, d is a real number of 0 to 4, R ⁷ is a hydrocarbon group having 1 to 20 carbon atoms, and X ¹ is a halogen atom)

The inert hydrocarbon solvent used for the reaction between the organic magnesium compound (A-1) and 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.

First, the organic magnesium compound (A-1) is described. The organic magnesium compound (A-1) is in the form of an organic magnesium complex soluble in an inert hydrocarbon solvent, including all dialkyl magnesium compounds and complexes of the compound with other metal compounds. The relationship between the symbols α, β, a, b, and c, nα+2β=a+b+c, represents the atomic valence of the metal atom and the stoichiometry of the substituent.

In Formula 1, the alkyl group having 2 to 20 carbon atoms represented by ^R2 and ^R3 is not particularly limited, and examples thereof include alkyl, cycloalkyl or aryl groups, and specifically, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, phenyl, etc. Alkyl groups are particularly preferred. When α>0, as the metal atom ^M1 , metal atoms belonging to the group consisting of Groups 12, 13 and 14 of the periodic table can be used, and examples thereof include zinc, boron, aluminum, etc. Aluminum and zinc are particularly preferred.

The ratio β/α of magnesium to metal atom ^M1 is not particularly limited, and is preferably 0.1 to 30, and more preferably 0.5 to 10. In addition, when an organic magnesium compound with a predetermined ratio of α=0 is used, for example, when ^R2 is 1-methylpropyl, etc., which is soluble in an inert hydrocarbon solvent, such a compound will also produce a better result for the present embodiment.

In the above (Formula 1), it is recommended that R ² and R ³ when α=0 satisfy any one of the following three groups (1), (2), and (3). Group (1): At least one of R ² and R ³ is a di- or tertiary alkyl group having 4 to 6 carbon atoms, preferably both of R ² and R ³ are alkyl groups having 4 to 6 carbon atoms and at least one of them is a di- or tertiary alkyl group. Group (2): R ² and R ³ are alkyl groups having different carbon atoms, 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. Group (3): At least one of R ² and R ³ is a alkyl group having 6 or more carbon atoms, preferably an alkyl group having a total of 12 or more carbon atoms contained in R ² and R ³ .

These groups are specifically shown below.

In the above group (1), examples of the secondary or tertiary alkyl group having 4 to 6 carbon atoms include 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl, 2-methylbutyl, 2-ethylpropyl, 2,2-dimethylpropyl, 2-methylpentyl, 2-ethylbutyl, 2,2-dimethylbutyl, and 2-methyl-2-ethylpropyl. 1-methylpropyl is particularly preferred.

In addition, examples of the alkyl group having 2 or 3 carbon atoms in the above group (2) include ethyl, 1-methylethyl, propyl, etc. Among them, ethyl is particularly preferred. In addition, examples of the alkyl group having 4 or more carbon atoms are not particularly limited, and specifically, examples include butyl, pentyl, hexyl, heptyl, octyl, etc. Among them, butyl and hexyl are particularly preferred.

Furthermore, the alkyl group having 6 or more carbon atoms in the above group (3) is not particularly limited, and examples thereof include hexyl, heptyl, octyl, nonyl, decyl, phenyl, 2-naphthyl, etc. Among the alkyl groups, alkyl groups are preferred, and among the alkyl groups, hexyl and octyl groups are particularly preferred.

Generally, as the number of carbon atoms contained in the alkyl group increases, the alkyl group tends to be more easily dissolved in an inert hydrocarbon solvent, and the viscosity of the solution tends to increase. Therefore, in terms of handling, it is preferred to use an alkyl group with an appropriately long chain. Furthermore, the above-mentioned organic magnesium compound can be used after being diluted with an inert hydrocarbon solvent, and even if the solution contains or contains a trace amount of Lewis base compounds such as ethers, esters, and amines, it does not affect the use.

Next, ^Y1 is explained.

In the above (Formula 1), ^Y1 is any one of alkoxy, silanyloxy, allyloxy, amino, amide, -N= ^CR4 , ^R5 , ^-SR6 (wherein ^R4 , ^R5 and ^R6 each independently represent a alkyl group having 2 to 20 carbon atoms), or β-keto acid residue.

In the above (Formula 1), the alkyl group represented by R ⁴ , R ⁵ and R ⁶ is preferably an alkyl group or an aryl group having 1 to 12 carbon atoms, and more preferably an alkyl group or an aryl group having 3 to 10 carbon atoms. There is no particular limitation, 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, naphthyl, etc. In particular, butyl, 1-methylpropyl, 2-methylpentyl and 2-ethylhexyl are preferred.

Furthermore, in the above (Formula 1), ^Y1 is preferably an alkoxy group or a silaneoxy group.

The alkoxy group is not particularly limited, and preferred are, for example, a methoxy group, an ethoxy group, a propoxy group, a 1-methylethoxy group, a butoxy group, a 1-methylpropoxy group, a 1,1-dimethylethoxy group, a pentyloxy group, a hexyloxy group, a 2-methylpentyloxy group, a 2-ethylbutoxy group, a 2-ethylpentyloxy group, a 2-ethylhexyloxy group, a 2-ethyl-4-methylpentyloxy group, a 2-propylheptyloxy group, a 2-ethyl-5-methyloctyloxy group, an octyloxy group, a phenoxy group, and a naphthyloxy group. In particular, more preferred are a butoxy group, a 1-methylpropoxy group, a 2-methylpentyloxy group, and a 2-ethylhexyloxy group.

The silyloxy group is not particularly limited, and preferred are, for example, hydrodimethylsilyloxy, ethylhydromethylsilyloxy, diethylhydromethylsilyloxy, trimethylsilyloxy, ethyldimethylsilyloxy, diethylmethylsilyloxy, triethylsilyloxy, etc. In particular, hydrodimethylsilyloxy, ethylhydromethylsilyloxy, diethylhydromethylsilyloxy, and trimethylsilyloxy are more preferred.

The synthesis method of the organic magnesium compound (A-1) is not particularly limited. For example, the organic magnesium compound belonging to the group consisting of the formula ^R2MgX1 and the formula ^R2Mg ( ^R2 has the same meaning as above, ^{and X1} is a halogen atom) can be ^reacted with an organic metal compound belonging to the group consisting of ^the formula ^M1R3n and ^M1R3 _(n-1) H ( ^M1 and ^R3 have the same meaning as above, _and n represents the atomic valence of ^M1 ) in an inert hydrocarbon solvent at a temperature of 25°C to 150°C, and then, if necessary, reacted with a compound represented by the formula ^Y1 -H ( ^Y1 has the same meaning as above), or with an organic magnesium compound and/or an organic aluminum compound having a functional group represented by ^Y1 , thereby synthesizing the organic magnesium compound. When an organic magnesium compound soluble in an inert hydrocarbon solvent is reacted with a compound represented by formula Y ¹ -H, the order of the reaction is not particularly limited. For example, any of a method of adding the compound represented by formula Y ¹ -H to the organic magnesium compound, a method of adding the organic magnesium compound to the compound represented by formula Y ¹ -H, or a method of adding both simultaneously can be used.

The molar composition ratio c/(α+β) of ^Y1 to all metal atoms in the organic magnesium compound (A-1) is preferably 0≦c/(α+β)≦2, and more preferably 0≦c/(α+β)<1. By making the molar composition ratio of ^Y1 to all metal atoms 2 or less, the reactivity of the organic magnesium compound (A-1) to the titanium compound (A-2) tends to be improved.

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

The titanium compound (A-2) is a titanium compound represented by the following formula 2. (A-2): Ti(OR ⁷ ) _d X ¹ _(4-d) ... (Formula 2) (In Formula 2, d is a real number of 0 to 4, R ⁷ is a hydrocarbon group having 1 to 20 carbon atoms, and X ¹ is a halogen atom)

In the above (Formula 2), d is preferably greater than or equal to 0 and less than or equal to 1, and more preferably 0.

In addition, the alkyl group represented by ^R7 in the above (Formula 2) is not particularly limited, and examples thereof include aliphatic alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, heptyl, octyl, decyl, and allyl; alicyclic alkyl groups such as cyclohexyl, 2-methylcyclohexyl, and cyclopentyl; and aromatic alkyl groups such as phenyl and naphthyl. Aliphatic alkyl groups are particularly preferred.

Examples of the halogen atom represented by ^X1 include a chlorine atom, a bromine atom, and an iodine atom. A chlorine atom is particularly preferred. The titanium compound (A-2) is particularly preferably titanium tetrachloride. In this embodiment, two or more compounds selected from the above may be used in combination.

Next, the reaction between the organic magnesium compound (A-1) and the titanium compound (A-2) is described.

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

The reaction temperature is not particularly limited, but is preferably in the range of -80°C to 150°C, more preferably in the range of -40°C to 100°C.

The order of adding the organic magnesium compound (A-1) and the titanium compound (A-2) is not particularly limited. The method of adding the titanium compound (A-2) after the organic magnesium compound (A-1), adding the organic magnesium compound (A-1) after the titanium compound (A-2), or adding the organic magnesium compound (A-1) and the titanium compound (A-2) at the same time may be adopted. Preferably, the method of adding the organic magnesium compound (A-1) and the titanium compound (A-2) at the same time is adopted. In the present embodiment, the solid catalyst component [A] obtained by the above reaction is used as a slurry solution using an inert hydrocarbon solvent.

As another example of the Ziegler-Natta catalyst component used in the present embodiment, the following catalyst for olefin polymerization is preferred, which comprises a solid catalyst component [C] and an organic metal compound component [B]. The solid catalyst component [C] is prepared by the following method: an organic magnesium compound (C-4) soluble in an inert hydrocarbon solvent as shown in the following (Formula 5) and a titanium compound (C-5) as shown in the following (Formula 6) are supported on a carrier (C-3) prepared by reacting an organic magnesium compound (C-1) soluble in an inert hydrocarbon solvent as shown in the following (Formula 3) and a chlorinating agent (C-2) as shown in the following (Formula 4).

(C-1): (M ² ) _γ (Mg) _δ (R ⁸ ) _e (R ⁹ ) _f (OR ¹⁰ ) _g ……(Formula 3) (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 respectively alkyl groups having 1 to 20 carbon atoms, 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 the atomic valence of M ² )).

(C-2): H _h SiCl _i R ¹¹ _{(4-(h + i))} ……(Formula 4) (In Formula 4, R ¹¹ is a alkyl group having 1 to 12 carbon atoms, and h and i are real numbers satisfying the following relationship: 0＜h, 0＜i, 0＜h＋i≦4)

(C-4): (M ¹ ) _α (Mg) _β (R ² ) _a (R ³ ) _b Y ¹ _c …… (Formula 5) (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 are alkyl groups having 2 to 20 carbon atoms, and Y ¹ is an alkoxy group, a silanyloxy group, an allyloxy group, an amino group, an amide group, -N＝CR ⁴ , R ⁵ , -SR ⁶ (Here, R ⁴ , R ⁵ and R ⁶ represent alkyl groups having 1 to 20 carbon atoms, and when c is 2, Y ¹ may be different), any one 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 the atomic valence of M ¹ )).

(C-5): Ti(OR ⁷ ) _d X ¹ _(4-d) ... (Formula 6) (In Formula 6, d is a real number of 0 to 4, R ⁷ is a hydrocarbon group having 1 to 20 carbon atoms, and X ¹ is a halogen atom)

First, the organic magnesium compound (C-1) is described. The organic magnesium compound (C-1) is in the form of an organic magnesium complex soluble in an inert hydrocarbon solvent, including all dialkyl magnesium compounds and complexes of the compound with other metal compounds. The relationship between the symbols γ, δ, e, f and g in formula 3, kγ+2δ=e+f+g, represents the atomic valence of the metal atom and the stoichiometry of the substituent.

In the above formula 3, the alkyl groups represented by ^R8 to ^R9 are not particularly limited, and may be, for example, alkyl, cycloalkyl or aryl groups, and specifically, may be methyl, ethyl, propyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, phenyl, etc. Among them, it is preferred that ^R8 and ^R9 are alkyl groups. When α>0, as the metal atom ^M2 , metal atoms belonging to the group consisting of the 12th, 13th and 14th groups of the periodic table may be used, and examples thereof include zinc, boron, aluminum, etc. Aluminum and zinc are particularly preferred.

The ratio δ/γ of magnesium to metal atom ^M2 is not particularly limited, and is preferably 0.1 to 30, and more preferably 0.5 to 10. In addition, in the case of a prescribed organic magnesium compound with γ=0, for example, when ^R8 is 1-methylpropyl, etc., it is soluble in an inert hydrocarbon solvent, and such a compound will also produce a better result for this embodiment.

In the above (Formula 3), when γ=0, R ⁸ and R ⁹ are preferably any one of the following three groups (1), (2), and (3). Group (1): At least one of R ⁸ and R ⁹ is a di- or tertiary alkyl group having 4 to 6 carbon atoms, preferably both of R ⁸ and R ⁹ have 4 to 6 carbon atoms, and at least one of them is a di- or tertiary alkyl group. Group (2): R ⁸ and R ⁹ are alkyl groups having different carbon atoms, preferably R ⁸ is an alkyl group having 2 or 3 carbon atoms, and R ⁹ is an alkyl group having 4 or more carbon atoms. Group (3): At least one of R ⁸ and R ⁹ is a alkyl group having 6 or more carbon atoms, preferably an alkyl group having a total carbon number of 12 or more contained in R ⁸ and R ^9. Specific examples of these groups are shown below.

As the secondary or tertiary alkyl group having 4 to 6 carbon atoms 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, etc. can be used. 1-methylpropyl is particularly preferred.

In addition, examples of the alkyl group having 2 or 3 carbon atoms in group (2) include ethyl, 1-methylethyl, propyl, etc., and ethyl is particularly preferred. In addition, examples of the alkyl group having 4 or more carbon atoms include, but are not particularly limited to, butyl, pentyl, hexyl, heptyl, octyl, etc., and butyl and hexyl are particularly preferred.

Furthermore, the alkyl group having 6 or more carbon atoms in group (3) is not particularly limited, and examples thereof include hexyl, heptyl, octyl, nonyl, decyl, phenyl, 2-naphthyl, etc. Among the alkyl groups, alkyl groups are preferred, and among the alkyl groups, hexyl and octyl groups are particularly preferred.

Generally, as the number of carbon atoms contained in the alkyl group increases, the alkyl group tends to be more soluble in an inert hydrocarbon solvent and the viscosity of the solution tends to increase. Therefore, in terms of handling properties, it is preferred to use an alkyl group with an appropriate long chain. Furthermore, the above-mentioned organic magnesium compound is used as an inert hydrocarbon solution, and even if the solution contains or contains trace amounts of Lewis base compounds such as ethers, esters, and amines, it does not affect the use.

Next, the alkoxy group (OR ¹⁰ ) in the above (Formula 3) will be described.

The alkyl group represented by ^R10 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. ^R10 is 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.

The synthesis method of the organic magnesium compound (C-1) is not particularly limited, but is preferably the following method: an organic magnesium compound belonging to the group consisting of formula R ⁸ MgX ¹ and formula R ⁸ Mg (R ⁸ has the same meaning as above, and X ¹ is a halogen atom) and an organic metal compound belonging to the group consisting of formula M ² R ⁹ _k and formula M ² R ⁹ _(k-1) H (M ² , R ⁹ and k have the same meanings as above) are reacted in an inert hydrocarbon solvent at a temperature of 25° C. to 150° C., and if necessary, the reaction is continued with an alcohol having a alkyl group represented by R ⁹ (R ⁹ has the same meaning as above) or an alkoxy magnesium compound having a alkyl group represented by R ⁹ which is soluble in an inert hydrocarbon solvent, and/or an alkoxy aluminum compound.

When an organic magnesium compound soluble in an inert hydrocarbon solvent is reacted with an alcohol, the order of the reaction is not particularly limited, and any of a method of adding alcohol to the organic magnesium compound, a method of adding the organic magnesium compound to the alcohol, or a method of adding both simultaneously can be used.

The reaction ratio of the organic magnesium compound soluble in an inert hydrocarbon solvent and the alcohol is not particularly limited. It is preferred that the molar composition ratio of the alkoxy group to all metal atoms in the alkoxy-containing organic magnesium compound obtained as a result of the reaction is g/(γ+δ) 0≦g/(γ+δ)≦2, and more preferably 0≦g/(γ+δ)<1.

Next, the chlorinating agent (C-2) is described. The chlorinating agent (C-2) is a silicon chloride compound having at least one Si-H bond as shown in the following (Formula 4).

(C-2): H _h SiCl _i R ¹¹ _{(4-(h + i))} ……(Formula 4) (In Formula 4, R ¹¹ is a alkyl group having 1 to 12 carbon atoms, and h and i are real numbers satisfying the following relationship: 0＜h, 0＜i, 0＜h＋i≦4)

In the above (Formula 4), the alkyl group represented by R ¹¹ is not particularly limited, and examples thereof include aliphatic alkyl groups, alicyclic alkyl groups, aromatic alkyl groups, and specifically, methyl, ethyl, propyl, 1-methylethyl, butyl, pentyl, hexyl, octyl, decyl, cyclohexyl, phenyl, etc. 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 methyl, ethyl, propyl, 1-methylethyl, is more preferred. In addition, h and i are numbers greater than 0 that satisfy the relationship of h+i≦4, and i is preferably 2 to 3.

Such compounds are not particularly limited, and examples thereof include HSiCl ₃ , HSiCl ₂ CH ₃ , HSiCl ₂ C ₂ H ₅ , HSiCl ₂ (C ₃ H ₇ ), HSiCl ₂ (2-C ₃ H ₇ ), HSiCl ₂ (C ₄ H ₉ ), HSiCl ₂ (C ₆ H ₅ ), HSiCl ₂ (4-Cl-C ₆ H ₄ ), HSiCl ₂ (CH═CH ₂ ), HSiCl ₂ (CH ₂ C ₆ H ₅ ), HSiCl ₂ (1-C ₁₀ H ₇ ), HSiCl ₂ (CH ₂ CH═CH ₂ ), H ₂ SiCl(CH ₃ ), H ₂ SiCl(C ₂ H ₅ ), HSiCl(CH ₃ ) ₂ , and HSiCl(C ₂ H ₅ ) ₂ , HSiCl(CH ₃ )(2-C ₃ H ₇ ), HSiCl(CH ₃ )(C ₆ H ₅ ), HSiCl(C ₆ H ₅ ) ₂ , etc. These compounds or a mixture of two or more selected from these compounds are used as the silicon chloride compound. Among them, HSiCl ₃ , HSiCl ₂ CH ₃ , HSiCl(CH ₃ ) ₂ , HSiCl ₂ (C ₃ H ₇ ) are preferred, and HSiCl ₃ and HSiCl ₂ CH ₃ are more preferred.

Next, the reaction between the organic magnesium compound (C-1) and the chlorinating agent (C-2) is described. During the reaction, it is preferred to dilute the chlorinating agent (C-2) with an inert hydrocarbon solvent, a chlorinated hydrocarbon such as 1,2-dichloroethane, o-dichlorobenzene, dichloromethane, or an ether medium such as diethyl ether, tetrahydrofuran, or a mixed medium thereof. Among them, inert hydrocarbon solvents are more preferred in terms of catalyst performance.

The reaction ratio of the organic magnesium compound (C-1) and the chlorinating agent (C-2) is not particularly limited. The amount of silicon atoms contained in the chlorinating agent (C-2) is preferably 0.01 mol to 100 mol, more preferably 0.1 mol to 10 mol, based on 1 mol of magnesium atoms contained in the organic magnesium compound (C-1).

The reaction method of the organic magnesium compound (C-1) and the chlorinating agent (C-2) is not particularly limited, and any of the following methods can be used: a simultaneous addition method in which the organic magnesium compound (C-1) and the chlorinating agent (C-2) are simultaneously introduced into a reactor and allowed to react, 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. Among these, the 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 preferred. The support (C-3) obtained by the above reaction is preferably separated by filtration or decanting, and then thoroughly washed with an inert hydrocarbon solvent to remove unreacted products and by-products.

The reaction temperature of the organic magnesium compound (C-1) and the chlorinating agent (C-2) is not particularly limited, but is preferably 25°C to 150°C, more preferably 30°C to 120°C, and further preferably 40°C to 100°C.

In the simultaneous addition method in which the organic magnesium compound (C-1) and the chlorinating agent (C-2) are simultaneously introduced into a reactor and reacted, it is preferred that the temperature of the reactor be adjusted to a predetermined temperature in advance, and the temperature in the reactor be adjusted to the predetermined temperature while the simultaneous addition is performed, thereby adjusting the reaction temperature to the predetermined temperature. In the method in which the organic magnesium compound (C-1) is introduced into the reactor after the chlorinating agent (C-2) is previously loaded into the reactor, it is preferred that the temperature of the reactor after the chlorinating agent (C-2) is introduced be adjusted to the predetermined temperature, and the temperature in the reactor be adjusted to the predetermined temperature while the organic magnesium compound is introduced into the reactor, thereby adjusting the reaction temperature to the predetermined temperature. In the method of introducing the chlorinating agent (C-2) into the reactor after the organic magnesium compound (C-1) is previously charged into the reactor, it is preferred that the temperature of the reactor after the organic magnesium compound (C-1) is charged is adjusted to a predetermined temperature, and the temperature in the reactor is adjusted to the predetermined temperature while the chlorinating agent (C-2) is introduced into the reactor, thereby adjusting the reaction temperature to the predetermined temperature.

Next, the organic magnesium compound (C-4) is described. As (C-4), the one represented by the above-mentioned (Formula 5) is preferred.

(C-4): (M ¹ ) _α (Mg) _β (R ² ) _a (R ³ ) _b Y ¹ _c …… (Formula 5) (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 are alkyl groups having 2 to 20 carbon atoms, and Y ¹ is an alkoxy group, a silanyloxy group, an allyloxy group, an amino group, an amide group, -N＝CR ⁴ , R ⁵ , -SR ⁶ (Here, R ⁴ , R ⁵ and R ⁶ represent alkyl groups having 1 to 20 carbon atoms, and when c is 2, Y ¹ may be different), any one 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＜a＋b, 0≦c/(α＋β)≦2, nα＋2β＝a＋b＋c (here, n represents the atomic valence of M ¹ )).

The amount of the organic magnesium compound (C-4) used is preferably such that the molar ratio of the magnesium atoms contained in (C-4) to the titanium atoms contained in the titanium compound (C-5) is 0.1 to 10, more preferably 0.5 to 5.

The reaction temperature of the organic magnesium compound (C-4) and the titanium compound (C-5) is not particularly limited, but is preferably in the range of -80°C to 150°C, more preferably in the range of -40°C to 100°C.

The concentration of the organic magnesium compound (C-4) when used is not particularly limited, but is preferably 0.1 mol/L to 2 mol/L, more preferably 0.5 mol/L to 1.5 mol/L, based on the magnesium atom contained in the organic magnesium compound (C-4). In addition, the organic magnesium compound (C-4) is preferably diluted using an inert hydrocarbon solvent.

There is no particular limitation on the order of adding the organic magnesium compound (C-4) and the titanium compound (C-5) to the carrier (C-3). The method may be any of the following: adding the titanium compound (C-5) after (C-4), adding the organic magnesium compound (C-4) after the titanium compound (C-5), or adding the organic magnesium compound (C-4) and the titanium compound (C-5) at the same time. Among them, the method of adding the organic magnesium compound (C-4) and the titanium compound (C-5) at the same time is preferred. The reaction of the organic magnesium compound (C-4) and the titanium compound (C-5) is carried out in an inert hydrocarbon solvent, preferably using an aliphatic hydrocarbon solvent such as hexane or heptane. The catalyst obtained in this way is used as a slurry solution using an inert hydrocarbon solvent.

Next, the titanium compound (C-5) is described. In this embodiment, (C-5) is the titanium compound represented by (Formula 6) above.

(C-5): Ti(OR ⁷ ) _d X ¹ _(4-d) ... (Formula 6) (In Formula 6, d is a real number of 0 to 4, R ⁷ is a hydrocarbon group having 1 to 20 carbon atoms, and X ¹ is a halogen atom)

In the above (Formula 6), the alkyl group represented by ^R7 is not particularly limited, and examples thereof include aliphatic alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, hexyl, 2-ethylhexyl, heptyl, octyl, decyl, and allyl; alicyclic alkyl groups such as cyclohexyl, 2-methylcyclohexyl, and cyclopentyl; and aromatic alkyl groups such as phenyl and naphthyl. Among them, aliphatic alkyl groups are preferred. The halogen atom represented by ^X1 is not particularly limited, and examples thereof include chlorine atom, bromine atom, and iodine atom. Among them, chlorine atom is preferred. The titanium compound (C-5) selected from the above may be used alone or in combination of two or more.

The amount of the titanium compound (C-5) used is not particularly limited. The molar ratio of titanium atoms contained in the titanium compound (C-5) to magnesium atoms contained in the carrier (C-3) is preferably 0.01 to 20, more preferably 0.05 to 10.

The reaction temperature of the titanium compound (C-5) is not particularly limited, but is preferably in the range of -80°C to 150°C, more preferably in the range of -40°C to 100°C.

In the present embodiment, the method for supporting the titanium compound (C-5) on the carrier (C-3) is not particularly limited. A method of reacting the carrier (C-3) with an excess of the titanium compound (C-5) or a method of efficiently supporting the titanium compound (C-5) by using a third component can be used. Preferably, the method of supporting by reacting the titanium compound (C-5) with an organic magnesium compound (C-4) is used.

Next, the organic metal compound component [B] used in the present embodiment is described. The solid catalyst component used in the present embodiment is combined with the organic metal compound component [B] to form a highly active polymerization catalyst. The organic metal compound component [B] is sometimes referred to as an "auxiliary catalyst". The organic metal compound component [B] is preferably a compound containing a metal belonging to the group consisting of Group 1, Group 2, Group 12 and Group 13 of the periodic table, and is particularly preferably an organic aluminum compound and/or an organic magnesium compound.

As the organic aluminum compound used as the organic metal compound component [B], it is preferred to use the compound represented by the following (Formula 7) alone or in combination.

AlR ¹² _j Z ¹ _(3-j) ……(Formula 7)

(In Formula 7, ^R12 is a alkyl group having 1 to 20 carbon atoms, ^Z1 is a group selected from the group consisting of a hydrogen atom, a halogen atom, an alkoxy group, an allyloxy group, and a siloxy group, and j is a number of 2 to 3)

In the above (Formula 7), the alkyl group having 1 to 20 carbon atoms represented by R ¹² is not particularly limited, and includes, for example, aliphatic alkyl groups, aromatic alkyl groups, and alicyclic alkyl groups. Specific examples of the organic aluminum compound include trimethyl aluminum, triethyl aluminum, tripropyl aluminum, tributyl aluminum, tri(2-methylpropyl) aluminum (or triisobutyl aluminum), tripentyl aluminum, tri(3-methylbutyl) aluminum, trihexyl aluminum, trioctyl aluminum, tridecyl aluminum, and other trialkyl aluminums, diethyl aluminum chloride, ethyl aluminum dichloride, di(2-methylpropyl) aluminum, and di(3-methylbutyl) aluminum. ) halogenated aluminum compounds such as aluminum chloride, ethylaluminum sesquichloride, diethylaluminum bromide, alkoxyaluminum compounds such as diethylaluminum ethanol, di(2-methylpropyl)aluminum butoxide, silaneoxyaluminum compounds such as dimethylhydrosiloxyaluminum dimethyl, ethylmethylhydrosiloxyaluminum diethyl, ethyldimethylsiloxyaluminum diethyl, and mixtures thereof. In particular, trialkylaluminum compounds are preferred.

The organic magnesium compound used as the organic metal compound component [B] is preferably an organic magnesium compound soluble in an inert hydrocarbon solvent and represented by the above-mentioned (Formula 3). (M ² ) _γ (Mg) _δ (R ⁸ ) _e (R ⁹ ) _f (OR ¹⁰ ) _g ……(Formula 3) (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 respectively alkyl groups having 1 to 20 carbon atoms, 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 the atomic valence of M ² )).

The organic magnesium compound is in the form of an organic magnesium complex soluble in an inert hydrocarbon solvent, including all dialkyl magnesium compounds and complexes of the compound with other metal compounds. γ, δ, e, f, g, M ² , R ⁸ , R ⁹ , OR ¹⁰ are as described above. The organic magnesium compound is preferably highly soluble in an inert hydrocarbon solvent, and therefore preferably δ/γ is in the range of 0.5 to 10, and more preferably M ² is an aluminum compound.

The ratio of the solid catalyst component to the organometallic compound component [B] is not particularly limited, but is preferably 1 mmol to 3,000 mmol per 1 g of the solid catalyst component.

[Polymerization conditions] In the production of polyethylene powder in the present embodiment, the polymerization method is not particularly limited. From the perspective of being able to efficiently remove the polymerization heat, it is preferred to use a slurry polymerization method to polymerize ethylene alone or copolymerize monomers containing ethylene. Furthermore, it is preferred to use multi-stage polymerization or parallel polymerization. Multi-stage polymerization is to divide the polymerization into two or more stages with different reaction conditions. Parallel polymerization is to carry out polymerization in two or more reactors with different reaction conditions and mix them.

In the slurry polymerization method, an inert hydrocarbon medium is used as the medium.

The above-mentioned inert hydrocarbon medium is not particularly limited, and examples thereof include 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 ethyl chloride, chlorobenzene, and dichloromethane; and mixtures thereof.

In the polymerization step of polyethylene powder, it is preferred to use an inert hydrocarbon medium having a carbon number of 6 or more and 10 or less. By making the carbon number 6 or more, low molecular weight components generated by side reactions during ethylene polymerization and polyethylene degradation are more easily dissolved and can be easily removed by the step of separating polyethylene from the polymerization medium. By making the carbon number 10 or less, there is a tendency to suppress the polyethylene powder from adhering to the reaction tank, etc., thereby enabling stable industrial operation.

The polymerization reaction can be carried out by any of batch, semi-continuous or continuous methods, preferably by continuous polymerization.

Ethylene gas, solvent, catalyst, etc. are continuously supplied to the polymerization system and discharged continuously together with the generated polyethylene, thereby suppressing the rapid reaction of ethylene and causing local high temperature, making the polymerization system more stable. If ethylene is reacted in a uniform state in the system, the generation of branches and double bonds in the polymer chain is suppressed, and the low molecular weight and cross-linking of polyethylene are not likely to occur. Therefore, the amount of unmelted material remaining when the ultra-high molecular weight polyethylene powder is melted or dissolved is reduced, coloring is suppressed, and the problem of reduced mechanical properties is not likely to occur. Therefore, a more uniform continuous type in the polymerization system is preferred.

The polymerization temperature is usually 30°C to 100°C, preferably 35°C to 95°C, and more preferably 40°C to 90°C. When the polymerization temperature is 30°C or higher, efficient production tends to be possible industrially. When the polymerization temperature is 100°C or lower, stable production tends to be possible continuously.

The polymerization pressure is usually at least normal pressure and no more than 5.0 MPa, preferably at least 0.1 MPa and no more than 4.0 MPa, and more preferably at least 0.1 MPa and no more than 3.0 MPa.

In the polymerization of polyethylene powder of the present embodiment, in the case of continuous two-stage polymerization using two polymerization reactions under different reaction conditions, it is preferred that the first stage of polymerization polymerizes polyethylene with a molecular weight lower than that of the second stage. For example, as described in the specification of West German Patent Application Publication No. 3127133, the molecular weight of polyethylene can be controlled by using methods such as making hydrogen exist in the polymerization system or changing the polymerization temperature. In addition, by adding hydrogen as a chain transfer agent to the polymerization system, it is easy to control the molecular weight within an appropriate range. In the case of adding hydrogen to the polymerization system, the molar fraction of hydrogen is preferably 0 mol% to 100 mol%, more preferably 0 mol% to 80 mol%, and further preferably 0 mol% to 60 mol%.

Furthermore, in the polymerization of polyethylene powder of the present embodiment, when two-stage polymerization is used, it is preferred to make the second-stage polymerization reaction proceed rapidly. The polymerization speed of polyethylene can be controlled by increasing the amount of the auxiliary catalyst, increasing the polymerization pressure, etc.

In the polymerization of polyethylene powder of the present embodiment, when two reactors with different reaction conditions are used to perform polymerization reactions in parallel and then mixed for continuous parallel polymerization, it is preferred to use one of the polymerization reactors to polymerize low molecular weight polyethylene with large particle size and use the other reactor to polymerize high molecular weight polyethylene with small particle size. The particle size of polyethylene can be controlled by polymerization pressure, the amount of catalyst added, etc.

Furthermore, in the polymerization of polyethylene powder according to the present embodiment, when continuous parallel polymerization is used, it is preferred to make the polymerization reaction of high molecular weight polyethylene with small particle size progress rapidly.

When polymerizing the polyethylene powder of this embodiment, in order to suppress the polymer from adhering to the polymerization reactor, an antistatic agent such as Stadis450 manufactured by The Associated Octel Company (agent: Maruwa Bussan) may be used. Stadis450 may also be diluted in an inert hydrocarbon medium and added to the polymerization reactor using a pump or the like. The amount added at this time is preferably added in the range of 0.10 ppm to 20 ppm, and more preferably in the range of 0.20 ppm to 10 ppm, relative to the polyethylene production per unit time.

In the production of polyethylene powder in the present embodiment, polyethylene powder is separated from solvent. Examples of solvent separation methods include decanting, centrifugal separation, and filter filtration. Centrifugal separation is preferred from the viewpoint of higher separation efficiency of polyethylene powder and solvent.

In the production of polyethylene powder in the present embodiment, the catalyst used in the production step is deactivated. The catalyst deactivation method is not particularly limited, and preferably the catalyst is deactivated after the polyethylene powder is separated from the solvent. By adding a catalyst deactivating agent after the solvent is separated, the precipitation of the catalyst components dissolved in the solvent can be suppressed. The catalyst deactivating agent is not limited to the following, and examples thereof include oxygen, water, alcohols, glycols, phenols, carbon monoxide, carbon dioxide, ethers, carbonyl compounds, alkynes, and the like.

In the production of polyethylene powder according to the present embodiment, it is preferred to perform a drying process after separating the solvent.

The drying temperature is preferably 70° C. to 120° C., more preferably 75° C. to 115° C., and further preferably 80° C. to 110° C.

When the drying temperature is 70°C or higher, efficient drying tends to be possible. When the drying temperature is 120°C or lower, drying tends to be possible while suppressing aggregation and thermal degradation of the polyethylene powder.

In the production of the polyethylene powder of this embodiment, it is preferred to perform a cooling treatment while stirring immediately after the drying treatment.

The cooling temperature is 0° C. or lower, more preferably -10° C. or lower. When the temperature is 0° C. or lower, the structure unique to the polyethylene powder of the present embodiment tends to be more apparent, that is, as the powder particle size decreases, the surface irregularities of the particles become larger.

The polyethylene powder of this embodiment can be directly put into various molding machines for molding processing, or the polyethylene powder can be mixed with organic peroxide and then put into various molding machines for molding processing.

[Organic peroxide] The organic peroxide (organic peroxide crosslinking agent) that can be used when molding the polyethylene powder of this embodiment is not particularly limited as long as it is an organic substance that helps crosslinking of the above-mentioned polyethylene and has an atomic group -O-O- in the molecule. Examples include organic peroxides such as dialkyl peroxides, diacyl peroxides, hydroperoxides, and ketone peroxides; organic peroxide esters such as alkyl peroxide esters; peroxydicarbonates, etc. The organic peroxide is not particularly limited, and specific examples thereof include diisopropyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylol Cyclohexane, 4,4-bis(tert-butylperoxy) valerate, butyl peroxide, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxybenzoate, peroxycarbonate O,O-tert-butyl-O-isopropyl ester, diacetyl peroxide, lauryl peroxide, tert-butyl isopropyl peroxide, α, α'-di(tert-butylperoxy)diisopropylbenzene, etc. Among them, preferred are 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (trade name "Perhexa 25B" manufactured by NOF Corporation), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3 (trade name "Perhexyne 25B" manufactured by NOF Corporation), diisopropylphenyl peroxide, and 1,1-bis(tert-butylperoxy)3,3,5-trimethylcyclohexane.

[Other ingredients] Furthermore, the polyethylene powder of the present embodiment can be used in combination with various known additives as needed. As a heat stabilizer, there is no particular limitation, for example, tetrakis[methylene(3,5-di-tert-butyl-4-hydroxy)hydrocinnamate]methane, distearyl thiodipropionate and other heat-resistant stabilizers; or bis(2,2',6,6'-tetramethyl-4-piperidinyl) sebacate, 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole and other weathering stabilizers, etc. As examples of other additives, for example, neutralizers, etc. can be cited. Neutralizers are used as chlorine collectors or molding processing aids contained in polyethylene powders, etc. There is no particular limitation on the neutralizing agent, and examples thereof include stearates of alkaline earth metals such as calcium, magnesium, and barium.

The additive in the polyethylene powder is extracted by Soxhlet extraction using tetrahydrofuran (THF) for 6 hours, and the extract is separated and quantified by liquid chromatography, thereby determining the content of the additive in the polyethylene powder of the present embodiment.

The polyethylene powder of this embodiment may be mixed with polyethylenes of different limiting viscosities, molecular weight distributions, etc., and may also be mixed with other resins such as low-density polyethylene, linear low-density polyethylene, polypropylene, polystyrene, etc.

[Molded body] The molded body of the present embodiment is a molded body of the polyethylene powder of the present embodiment described above. In addition, the molded body of the present embodiment can be obtained by molding a raw material including the polyethylene powder described above by various methods.

The forming method of the molded body of the present embodiment is not particularly limited, and examples thereof include pressure forming and extrusion forming. Pressure forming is a method in which a raw material including polyethylene powder is uniformly dispersed in a mold, heated and pressurized to form it, and then taken out after cooling. The pressurized molded body can be used directly as a product, or it can be finely processed into a final product after secondary processing such as cutting and slicing. On the other hand, extrusion forming is preferably performed using a screw extruder or a plunger extruder that moves a piston back and forth to perform extrusion. By changing the shape of the outlet of the extruder, various shapes of molded bodies such as flat plates, irregular products, and tubes can be obtained. Furthermore, block-shaped molded bodies such as round bars and corner columns may be finished into final products through secondary processing such as cutting and slicing.

[Application] The polyethylene powder molded body of this embodiment is not particularly limited and can be used for lining materials for ships, trucks, agricultural machinery, hoppers, and storage; pipes for ore transportation; gears and bearings for machinery; rollers for food transportation; guide rollers; linings for skis; artificial bones and artificial joints, etc.

Furthermore, the polyethylene powder of this embodiment can also be used as a raw material for microporous membranes, separators for lithium-ion secondary batteries or lead storage batteries, and high-strength fibers by wet molding using a solvent. [Example]

Hereinafter, the present embodiment will be described in more detail with reference to specific embodiments and comparative examples, but the present invention is not limited to the following embodiments and comparative examples.

In addition, ethylene and hexane used in the Examples and Comparative Examples were dehydrated using MS-3A (manufactured by Union Showa), and then hexane was deoxygenated by decompression and degassing using a vacuum pump before use.

[Measurement method and conditions] The physical properties of the polyethylene powders of the examples and comparative examples were measured using the following method.

(1) Viscosity average molecular weight Mv According to ISO1628-3 (2010), the viscosity average molecular weight Mv of the polyethylene powder obtained in the example and the comparative example was determined by the following method. First, 20 mg of polyethylene powder was weighed in a dissolving tube, and after nitrogen substitution in the dissolving tube, 20 mL of decahydronaphthalene (added with 1 g/L of 2,6-di-tert-butyl-4-methylphenol) was added, and the solution was stirred at 150°C for 2 hours to dissolve the polyethylene powder and prepare sample solutions. For the obtained sample solutions, the falling time (ts) between the mark lines was measured in a constant temperature bath at 135°C using a Cannon-Fenske viscometer (manufactured by Shibata Scientific Instruments Co., Ltd.: product number -100). Similarly, sample solutions with different amounts of polyethylene powder of 10 mg, 5 mg, and 2 mg were prepared, and the falling time (ts) between the marks was measured under the same conditions. As a blank sample, a sample solution without polyethylene powder but only decahydronaphthalene was prepared, and the falling time (tb) was measured under the same conditions.

According to the following formula, the reduced viscosity (ηsp/C) of the polyethylene powder is calculated. ηsp/C＝(ts/tb－1)/0.1 (Unit: dL/g) Next, the relationship between the concentration (C) (Unit: g/dL) and the reduced viscosity (ηsp/C) of the polyethylene powder is plotted, and an approximate linear equation is derived by the least square method. The equation is extrapolated to a concentration of 0 to calculate the limiting viscosity ([η]). Then, the viscosity average molecular weight Mv (g/mol) is calculated based on the above limiting viscosity [η] using the following (Formula A). Mv＝(5.34×10 ⁴ )×[η] ^1.49 (Formula A)

(2) Difference ΔMv between viscosity average molecular weight Mv ₇₅ and viscosity average molecular weight Mv ₁₅₀ Each polyethylene powder was graded using sieves with openings of 150 μm and 75 μm that conform to JIS Z 8801, and the powder on the 150 μm sieve and the powder that passed the 75 μm sieve were collected. The viscosity average molecular weight (Mv ₁₅₀ ) of the powder on the 150 μm sieve and the viscosity average molecular weight (Mv ₇₅ ) of the powder that passed the 75 μm sieve were measured according to the above-mentioned measurement method (1). The difference ΔMv (g/mol) (=Mv ₇₅ -Mv ₁₅₀ ) was calculated based on the obtained viscosity average molecular weight.

(3) Comonomer Content The comonomer content (mol %) of each polyethylene powder obtained in the Examples and Comparative Examples was measured by ¹³ C-NMR under the following conditions. Apparatus: AVANCEIII 500HD Prodigy (Bruker Biospin) Observation frequency: 125.77 MHz ( ¹³ C) Pulse width: 5.0 μsec Pulse repetition time: 5 sec Accumulated times: 10,000 times Measurement temperature: 120°C Standard: 29.9 ppm (PE: Sδδ) Solvent: oC ₆ D ₄ Cl ₂ Sample concentration: 0.1 g/mL Sample tube: 5 mmϕ The measurement sample was prepared by adding 0.6 mL of oC ₆ D ₄ Cl ₂ to 60 mg of polyethylene powder and dissolving the mixture by heating at 130°C.

(4) Average particle size X ₅₀ : 100 g of polyethylene powder is weighed in a 200 mL polyethylene cup, and 1 g of carbon black is added. The mixture is stirred with a spatula. The stirred polyethylene powder is placed in a sieve with openings of 300 μm, 212 μm, 150 μm, 106 μm, 75 μm, and 53 μm that conform to the JIS Z 8801 specification for classification. The mass of the polyethylene powder remaining on each sieve is integrated from the side with the smallest opening. In the obtained integral curve (cumulative distribution on the sieve), the particle size (sieve size) with 50% mass is set as the average particle size (μm).

(5) Bulk density a, tap density b, ratio a/b The bulk density a (g/cm ³ ) and tap density b (g/cm ³ ) were measured using a powder tester PT-X (manufactured by Hosokawa Micro) as follows. The sample supply device was vibrated to allow the polyethylene powder to flow into a 100 cm ³ stainless steel cylindrical container until the polyethylene powder accumulated in the container in a mountain shape. The excess polyethylene powder on the container was scraped off with a scraper to prepare a measurement sample. The value obtained by measuring the measurement sample was the bulk density a (g/cm ³ ). In addition, a 100 cm ³ stainless steel cylindrical container was covered, and the sample supply device was vibrated to make the polyethylene powder flow down, and the vibration was performed with a stroke length (vibration height) of 18 mm, a vibration speed of 60 times/minute, and a vibration number of 180 times. Afterwards, the excess polyethylene powder on the container was scraped off with a scraper, and the measurement sample was prepared. The value obtained by measuring the measurement sample was the tap density b (g/cm ³ ). In addition, the value of the loose density a measured in the above manner was divided by the value of the tap density b, and the obtained value was multiplied by 100 to obtain the value of the ratio a/b.

(6) Melt residue in the center of the cross section of the extruded molded body A single-shaft extruder with a screw diameter of 25 mm and L (screw length) / D (screw diameter) of 28 was used to form each polyethylene powder molded body. The screw used was a full-thread type, and the molding was performed at a barrel temperature of 210°C. A mold with a length of 600 mm was set at the front end of the extruder to form a 35 mm square molded body. Furthermore, the molding was performed at a mold front temperature of 180°C and a rear temperature of 40°C. In addition, the screw speed was adjusted in such a way that the discharge volume became 4 m/hour. Visually determine whether there is melt residue, that is, an unmelted portion, in the center of any cross section of the produced molded body. Furthermore, when molten residues are generated, they can be identified by the white turbidity in the center. The following is the criteria for determination. ○…No molten residues in the center of any cross section ×…Melted residues in the center of any cross section

(7) Impact strength of the center and end of the extruded molded product 120 mm × 15 mm × 10 mm test pieces were cut from the center and the inner side 3 mm from the end of each extruded molded product obtained by the above method, and the impact strength was measured by the Charpy impact test in accordance with ISO11542-2. Five test pieces were made and the average value of the five measurements was calculated. The average value of the impact strength of the center was divided by the average value of the impact strength of the end (average value of the impact strength of the center/average value of the impact strength of the end) to find the ratio of the impact strength of the center and end of the extruded molded product, and the judgment was made according to the following judgment criteria. ◎…The ratio of the impact strength of the center and the end of the extruded molded body is 0.9 or more ○…The ratio of the impact strength of the center and the end of the extruded molded body is 0.8 or more and less than 0.9 ×…The ratio of the impact strength of the center and the end of the extruded molded body is less than 0.8

(8) Voids in pressurized molded bodies 9 kg of each polyethylene powder was dropped into a 300 mm square, 100 mm high mold in a heated press molding machine by free fall, and the surface was evenly flattened. After compression molding at a set temperature of 210°C and a gauge pressure of 10 MPa for 3 hours, the pressurized molded bodies were made after a cooling process in which heating was stopped while maintaining the pressure. The pressurized molded bodies were cut at intervals of 100 mm, and three cross sections were observed using a 5x magnifying glass. The number of void defects in the cross section of the pressurized molded body was counted and judged according to the following judgment criteria. ◎…The total number of white spots in the 3 cross sections is 0 ○…The total number of white spots in the 3 cross sections is 1 ×…The total number of white spots in the 3 cross sections is 2 or more

[Catalyst synthesis method] [Preparation of solid catalyst component [A]] (1) Synthesis of raw material (a-1) Into an 8 L stainless steel autoclave fully purged with nitrogen, 2,000 mL of a 1 mol/L hexane solution of Mg ₆ (C ₄ H ₉ ) ₁₂ Al(C ₂ H ₅ ) ₃ (equivalent to 2000 mmol of magnesium and aluminum) was placed. While stirring at 50°C, 146 mL of a 5.47 mol/L hexane solution of n-butanol was added dropwise over 3 hours. The pipeline 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 designated as raw material [a-1]. In the raw material [a-1], the total concentration of magnesium and aluminum is 0.704 mol/L.

(2) Synthesis of raw material [a-2] Into an 8 L stainless steel autoclave fully purged with nitrogen, 2,000 mL of a 1 mol/L hexane solution of Mg ₆ (C ₄ H ₉ ) ₁₂ Al(C ₂ H ₅ ) ₃ (equivalent to 2000 mmol of magnesium and aluminum) was placed, and while stirring at 80°C, 240 mL of a hexane solution of 8.33 mol/L methyl hydropolysiloxane (manufactured by Shin-Etsu Chemical Co., Ltd.) was pressure-fed, and stirring was continued at 80°C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature and designated as raw material [a-2]. The total concentration of magnesium and aluminum in raw material [a-2] was 0.786 mol/L.

(3) Synthesis of [A-1] carrier Into an 8 L stainless steel autoclave fully purged with nitrogen, 1,000 mL of a 1 mol/L hexane solution of hydroxytrichlorosilane was placed, and 1340 mL of a hexane solution of an organic magnesium compound of the raw material [a-1] (equivalent to 943 mmol of magnesium) was added dropwise at 65°C for 3 hours, and then stirred at 65°C for 1 hour to allow the reaction to continue. After the reaction was completed, the supernatant was removed and washed four times with 1,800 mL of hexane to obtain the [A-1] carrier. The carrier was analyzed and the result showed that the magnesium content per 1 g of solid was 7.5 mmol.

(4) Preparation of solid catalyst component [A] 1,970 mL of hexane slurry containing 110 g of the above-mentioned [A-1] carrier was stirred at 10°C while adding 103 mL of a 1 mol/L hexane solution of titanium tetrachloride and 131 mL of the raw material [a-2] over 3 hours. After the addition, the reaction was continued at 10°C for 1 hour. After the reaction was completed, the supernatant was removed and washed with hexane 4 times to remove the unreacted raw material components, thereby preparing a solid catalyst component [A].

[Production of polyethylene powder] (Example 1) Polyethylene powder is produced by two-stage polymerization. Initially, in order to produce a low molecular weight component by the first-stage polymerization, hexane, ethylene, hydrogen and a catalyst are continuously supplied to a container-type 300 L polymerization reactor (1) equipped with a stirring device. The polymerization pressure is maintained at 0.31 MPa. The polymerization temperature is maintained at 70°C by jacket cooling. Hexane is supplied from the bottom of the polymerization reactor (1) at 40 L/hour. A solid catalyst component [A] is used as a catalyst, and Mg ₆ (C ₄ H ₉ ) ₁₂ Al(C ₂ H ₅ ) ₃ is used as an auxiliary catalyst. A solid catalyst component [A] was added from the middle of the liquid surface and the bottom of the polymerization reactor (1) at a rate of 1.5 g/hour, and an auxiliary catalyst was added from the middle of the liquid surface and the bottom of the polymerization reactor (1) at a rate of 10 mmol/hour. Hydrogen was used as a molecular weight regulator and supplied in such a manner that the gas phase molar concentration of hydrogen relative to the sum of ethylene and hydrogen (hydrogen/(ethylene+hydrogen)) became 4.32 mol%. Furthermore, hydrogen was supplied to the gas phase, and ethylene was supplied from the bottom of the polymerization reactor (1).

Next, in order to produce the high molecular weight component by the second stage polymerization, the polymer slurry solution in the first stage polymerization reactor (1) is introduced into a 300 L flash evaporation drum maintained at a pressure of 0.05 MPa and a temperature of 70°C. After the unreacted ethylene and hydrogen are separated, the slurry is introduced into the bottom of the second stage container type 300 L polymerization reactor (2) which is the same as the polymerization reactor (1) by a slurry pump. Hexane is introduced into the slurry pump at a rate of 110 L/hour. In addition, ethylene and auxiliary catalyst are continuously supplied to the polymerization reactor (2) to carry out polymerization. The polymerization pressure is maintained at 0.99 MPa and the polymerization temperature is maintained at 73°C. The cocatalyst Mg ₆ (C ₄ H ₉ ) ₁₂ Al(C ₂ H ₅ ) ₃ was added to the polymerization reactor (2) at a rate of 50 mmol/hour. Ethylene and the cocatalyst were supplied from the same positions as those of the polymerization reactor (1). In addition, hydrogen was not supplied during the second stage polymerization. High molecular weight polymerization was carried out in such a manner that the ratio of the mass of the high molecular weight component produced in the second stage polymerization reactor (2) to the sum of the mass of the low molecular weight component produced in the first stage polymerization reactor (1) and the mass of the high molecular weight component produced in the second stage polymerization reactor (2) (mass of the high molecular weight component produced in the second stage polymerization reactor (2)/(mass of the low molecular weight component produced in the first stage polymerization reactor (1) + mass of the high molecular weight component produced in the second stage polymerization reactor (2)) became 0.50. The production rate of polyethylene in the polymerization reactor (2) was 20 kg/hour.

The obtained polymer slurry was continuously pumped into a flash evaporation drum with a pressure of 0.04 MPa while keeping the level of the polymerization reactor (2) fixed to separate the unreacted ethylene.

Thereafter, the obtained polymer slurry is continuously fed into a centrifuge while keeping the level of the polymerization reactor (2) fixed, so as to separate the polymer (polyethylene powder) from other solvents.

The separated polyethylene powder was dried at 110°C while blowing nitrogen and stirring for 0.5 hours. Furthermore, in the drying step, steam was sprayed on the polyethylene powder after polymerization to deactivate the catalyst and auxiliary catalyst. Thereafter, the polyethylene powder was cooled by blowing nitrogen at -10°C for 10 minutes while stirring the dried polyethylene powder. After cooling, 500 ppm of calcium stearate (manufactured by Dainichi Chemical Co., Ltd., C60) was added to the polyethylene powder returned to room temperature and uniformly mixed using a Henschel mixer. Subsequently, the polyethylene powder was passed through a sieve with an opening of 425 μm, and the powder that did not pass through the sieve was removed, thereby obtaining the polyethylene powder of Example 1 having a viscosity average molecular weight Mv of 193×10 ⁴ g/mol. The properties of the polyethylene powder obtained in Example 1 are shown in Table 1.

(Example 2) Polyethylene powder was produced by two-stage polymerization in the same manner as in Example 1. In the first stage of polymerization, 1-butene was continuously supplied to ethylene at 0.90 mol% from the bottom of the polymerization reactor (1), and the gas phase molar concentration of hydrogen relative to the sum of ethylene and hydrogen was changed to 1.40 mol%. In the second stage of polymerization, the supply of 1-butene was stopped, and the concentration of 1-butene relative to ethylene was set to 0.07 mol%. The polymerization pressure was changed to 1.95 MPa and the polymerization temperature was 60°C. In addition, by the same operation as in Example 1, polyethylene powder of Example 2 having a viscosity average molecular weight Mv of 407×10 ⁴ g/mol and a copolymer content of 0.04 mol% was obtained. The production rate of polyethylene in the polymerization reactor (2) was 20 kg/hour. The properties of the polyethylene powder obtained in Example 2 are shown in Table 1.

(Example 3) Polyethylene powder is produced by parallel polymerization. Hexane, ethylene, 1-butene, hydrogen and a catalyst are continuously supplied to a container-type 300 L polymerization reactor (1) similar to that of Example 1 from the same position as that of Example 2. The polymerization pressure is maintained at 0.30 MPa and the polymerization temperature is 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 auxiliary catalyst was changed to a mixture of triisobutyl aluminum and diisobutyl aluminum cyanide (a mixture with a mass ratio of 9:1) 5 mmol/hour, the gas phase molar concentration of hydrogen was changed to 0.50 mol%, and the concentration of 1-butene relative to ethylene was changed to 0.46 mol%. Except for this, the polymerization reaction was carried out in the polymerization reactor (1) in the same manner as in the above-mentioned Example 2. The production rate of polyethylene in the polymerization reactor (1) was 10 kg/hour.

Simultaneously with the polymerization in polymerization reactor (1), polymerization was also carried out in a 300 L container-type polymerization reactor (2) similar to polymerization reactor (1). Hexane, ethylene, 1-butene and a catalyst were continuously supplied from the same position as in the above-mentioned Example 2. Furthermore, no hydrogen was added. The polymerization pressure was maintained at 1.23 MPa and the polymerization temperature was maintained at 60°C. The polymerization reaction was carried out in the polymerization reactor (2) in the same manner as in Example 2 except that 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 auxiliary catalyst was changed to Mg ₆ (C ₄ H ₉ ) ₁₂ Al(C ₂ H ₅ ) ₃ 50 mmol/hour, and the concentration of 1-butene was changed to 0.46 mol% relative to ethylene. The production rate of polyethylene in the polymerization reactor (2) was 10 kg/hour.

In order to keep the polymerization reactor horizontally fixed, the polymer slurries of polymerization reactor (1) and polymerization reactor (2) were continuously introduced into a stirrer with a pressure of 0.04 MPa and a content of 300 L to separate the unreacted ethylene and hydrogen while stirring the polymer slurry. Thereafter, by the same operation as the above-mentioned Example 1, the polyethylene powder of Example 3 having a viscosity average molecular weight Mv of 415×10 ⁴ g/mol and a copolymer content of 0.04 mol% was obtained. The total production rate of polyethylene in polymerization reactor (1) and polymerization reactor (2) was 20 kg/hour. The properties of the polyethylene powder of Example 3 obtained are shown in Table 1.

(Example 4) Similarly to Example 3, polyethylene powder was produced by parallel polymerization. The polymerization pressure in the polymerization reactor (1) was changed to 0.31 MPa, the supply amount of the solid catalyst component [A] was changed to 0.3 g/hour, the supply amount of the auxiliary catalyst 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. Except for this, the polymerization reaction was carried out in the polymerization reactor (1) in the same manner as in Example 3. The production rate of polyethylene in the polymerization reactor (1) was 5 kg/hour.

The 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 amount 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.

Thereafter, by the same operation as in Example 3, polyethylene powder of Example 4 having a viscosity average molecular weight Mv of 630×10 ⁴ g/mol and a comonomer content of 0.03 mol% was obtained. The total production rate of polyethylene in the polymerization reactor (1) and the polymerization reactor (2) was 15 kg/hour. The properties of the polyethylene powder of Example 4 obtained are shown in Table 1.

(Example 5) Similarly to Example 2, polyethylene powder was produced by two-stage polymerization. The polymerization pressure in the second stage of polymerization was changed to 0.65 MPa, and the supply amount of the auxiliary catalyst was changed to 10 mmol/hour. The polymerization reaction was carried out in the polymerization reactor (1) and the polymerization reactor (2) in the same manner as in Example 2.

Then, by the same operation as in Example 2, polyethylene powder of Example 5 having a viscosity average molecular weight Mv of 404×10 ⁴ g/mol and a comonomer content of 0.03 mol% was obtained. The production rate of polyethylene in the polymerization reactor (2) was 20 kg/hour. The properties of the polyethylene powder of Example 5 obtained are shown in Table 1.

(Example 6) Similarly to Example 2, polyethylene powder was produced by two-stage polymerization. After the polymerization reaction in polymerization reactor (1) and polymerization reactor (2), the nitrogen blowing at -10°C for 10 minutes on the dried powder was omitted. Other than that, the same process as Example 2 was carried out.

Then, by the same operation as in Example 2, polyethylene powder of Example 6 having a viscosity average molecular weight Mv of 403×10 ⁴ g/mol and a comonomer content of 0.04 mol% was obtained. The production rate of polyethylene in the polymerization reactor (2) was 20 kg/hour. The properties of the polyethylene powder of Example 6 are shown in Table 1.

(Comparative Example 1) Polyethylene powder is produced by one-stage polymerization. Hexane, ethylene, hydrogen and a catalyst are continuously supplied to a container-type 300 L polymerization reactor (1) similar to that of Example 1 above from the same position as that of Example 1 above. The polymerization pressure is maintained at 0.30 MPa, and the polymerization temperature is maintained at 75°C. The flow rate of hexane is changed to 80 L/hour, the supply amount of the solid catalyst component [A] is changed to 0.3 g/hour, the mixture of triisobutylaluminum and diisobutylaluminum cyanide (a mixture with a mass ratio of 9:1, respectively) as an auxiliary catalyst is changed to 5 mmol/hour, and the gas phase molar concentration of hydrogen is changed to 0.27 mol%. Except for this, a polymerization reaction is carried out in the polymerization reactor (1) in the same manner as in Example 1 above. The production rate of polyethylene in the polymerization reactor (1) is 10 kg/hour.

Thereafter, the dried powder was not blown with nitrogen at -10°C for 10 minutes. The same operation as in Example 1 was performed to obtain polyethylene powder of Comparative Example 1 having a viscosity average molecular weight Mv of 330×10 ⁴ g/mol. The properties of the polyethylene powder of Comparative Example 1 are shown in Table 1.

(Comparative Example 2) Polyethylene powder was produced by two-stage polymerization in the same manner as in Example 2. The polymerization pressure in the second stage of polymerization was changed to 0.65 MPa, the amount of the auxiliary catalyst supplied was changed to 10 mmol/hour, and the dried powder was not blown with nitrogen at -10°C for 10 minutes. In addition, by the same operation as in Example 2, polyethylene powder of Comparative Example 2 having a viscosity average molecular weight Mv of 411×10 ⁴ g/mol and a copolymer content of 0.04 mol% was obtained. The production rate of polyethylene in the polymerization reactor (2) was 20 kg/hour. The properties of the polyethylene powder of Comparative Example 2 obtained are shown in Table 1.

(Comparative Example 3) Polyethylene powder was produced by two-stage polymerization in the same manner as in Example 1. In Comparative Example 3, a high molecular weight component was polymerized in the first stage polymerization, and a low molecular weight component was polymerized in the second stage polymerization. Furthermore, in the first stage of polymerization, hydrogen was not supplied, the polymerization pressure was changed to 0.27 MPa, and the polymerization temperature was changed to 74°C. In the second stage of polymerization, the polymerization pressure was changed to 0.56 MPa, the polymerization temperature was changed to 78°C, the supply amount of the auxiliary catalyst was changed to 10 mmol/hour, 1-butene was supplied at a concentration of 1.00 mol% for ethylene, hydrogen was supplied at a gas phase molar concentration of 0.20 mol%, and the dried powder was not blown with nitrogen at -10°C for 10 minutes. Except for this, by the same operation as the above-mentioned Example 1, a polyethylene powder of Comparative Example 3 with a viscosity average molecular weight Mv of 393×10 ⁴ g/mol and a copolymer content of 0.05 mol% was obtained. The production rate of polyethylene in the polymerization reactor (2) was 20 kg/hour. The properties of the polyethylene powder obtained in Comparative Example 3 are shown in Table 1.

(Comparative Example 4) Polyethylene powder was produced by two-stage polymerization in the same manner as in Example 1. In Comparative Example 4, as in Comparative Example 3, the high molecular weight component was polymerized in the first stage polymerization and the low molecular weight component was polymerized in the second stage polymerization. In the first stage of polymerization, hydrogen was not supplied, the polymerization pressure was changed to 0.27 MPa, and the polymerization temperature was changed to 74°C. In the second stage of polymerization, the polymerization pressure was changed to 1.68 MPa, the polymerization temperature was changed to 78°C, the supply amount of the cocatalyst was changed to 50 mmol/hour, 1-butene was supplied to ethylene at a concentration of 1.00 mol%, and hydrogen was supplied at a gas phase molar concentration of 0.20 mol%. Except for this, by the same operation as the above-mentioned Example 1, a polyethylene powder of Comparative Example 4 with a viscosity average molecular weight Mv of 391×10 ⁴ g/mol and a comonomer content of 0.06 mol% was obtained. The production rate of polyethylene in the polymerization reactor (2) was 20 kg/hour. The properties of the polyethylene powder of Comparative Example 4 are shown in Table 1.

[Table 1] Table 1 Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Embodiment 5 Embodiment 6 Comparison Example 1 Comparison Example 2 Comparison Example 3 Comparison Example 4 Viscosity average molecular weight Mv ×10 ⁴ g/mol 193 407 415 630 404 403 330 411 393 391 Average particle size X ₅₀ μm 102 95 89 77 92 93 99 95 101 99 ∆Mv (＝Mv75－Mv150) ×10 ⁴ g/mol 14 64 180 286 74 69 -20 60 -93 -96 Ratio a/b (＝100×(bulk density a/tapped density b)) % 94.5 92.4 92.2 88.9 83.3 85.9 82.6 80.2 79.9 84.0 Melt residue in the center of the cross section of the extruded body ○, × ○ ○ ○ ○ ○ ○ × × × × Impact strength ratio of the center and end of the extruded body ◎、○、× ◎ ◎ ◎ ◎ ◎ ◎ × × × × Voids in press-formed bodies ◎、○、× ◎ ◎ ◎ ◎ ○ ○ × × × × [Industrial Availability]

The polyethylene powder of the present invention can be used in the industry as a raw material for various molded bodies, microporous membranes, separators, and high-strength fibers.

Claims (8)

A polyethylene powder having a viscosity average molecular weight Mv of 100,000 (g/mol) to 10,000,000 (g/mol), an average particle size X ₅₀ of 50 μm to 200 μm based on cumulative mass, a difference ΔMv (where ΔMv = Mv 75 - Mv 150 ) between the viscosity average molecular weight Mv ₇₅ (g/mol) of the powder passing through the sieve when classified by a sieve with an opening of ₇₅ μm and the viscosity average molecular weight Mv ₁₅₀ (g/mol) of the powder on the sieve when classified by a sieve with an opening of ₁₅₀ μm is greater than 0 (g/mol) and is less than 4,000,000 (g/mol), and a bulk density a (g/cm ³ ) relative to a tap density b (g/cm ³ ) ratio a/b is 83.0(%) or more. The polyethylene powder of claim 1, wherein the above ratio a/b is greater than 88.0 (%). The polyethylene powder of claim 1 or 2, wherein the difference ΔMv is greater than 10 (g/mol) and is less than 3,000,000 (g/mol). A molded body is formed by molding a raw material comprising polyethylene powder as described in claim 1 or 2. A press-molded body is formed by press-molding a raw material comprising polyethylene powder as claimed in claim 1 or 2. An extruded body is formed by extruding a raw material comprising the polyethylene powder of claim 1 or 2. A microporous membrane using the polyethylene powder of claim 1 or 2. A high-strength fiber using the polyethylene powder of claim 1 or 2.