JP6710993B2 - Ultra high molecular weight polyethylene particles and method for producing the same - Google Patents

Description

The present invention relates to ultra-high-molecular-weight polyethylene particles having a narrow particle size distribution and not having coarse particles or fine particles and having excellent powder characteristics, and particularly, having a high viscosity average molecular weight and having a molecular weight distribution suitable for molding processing. The present invention relates to ultra-high molecular weight polyethylene particles having excellent average particle size and standard deviation of particle size, which have less catalyst residue and no resin coloring in compression molding or powder molding, and can be used for compression molding, powder molding, etc. The present invention provides ultra-high molecular weight polyethylene particles having excellent molding processability.

Polyethylene obtained by polymerizing ethylene is generally used as a general-purpose resin with a molecular weight of about 2 to 300,000, and ultra-high plastic considered to be one of the super engineering plastics with a molecular weight up to 1 to 7 million. There is molecular weight polyethylene. Ultra high molecular weight polyethylene has very high impact resistance in a wide temperature range from low temperature to high temperature, excellent wear resistance, self-lubricating property, chemical resistance, and specific gravity of 0.92 to 0.94. Compared to other engineering plastics, it has many excellent features such as being lightweight, having low water absorption and excellent dimensional stability. On the other hand, the fluidity when melted is extremely low, which makes it unsuitable for injection molding used in molding of general-purpose resins. A molding method, a method called stretch-spinning after melting in a solvent called gel spinning, a sintering method that gives a porous molded article having a space formed by overlapping of particles by partially fusing particles together, etc. Used.

As a method for obtaining such ultra-high molecular weight polyethylene particles, powder having a particle size of 840 μm or more is 10% or less of the whole, 90% or more of the whole is in the range of particle size 44 to less than 840 μm, and the average particle size is Ultra-high molecular weight polyolefin powder in the range of 200 to 700 μm (for example, refer to Patent Document 1) has been proposed.

Further, when the polyethylene particles contain a large amount of a metal component or a halogen component derived from a catalyst, problems such as corrosion of a mold used for compression molding, thread breakage due to foreign matter in gel spinning, and coloring of the resin itself may occur. As a high activity type catalyst as a countermeasure against these, for example, a catalyst component (A) obtained by reacting a composition obtained by reacting an organoaluminum halide with a composition obtained by heating metal magnesium, alcohol, and titanium tetraalcoholate and subjecting them to complex aging A catalyst system composed of a catalyst component (B) of an organometallic compound (see, for example, Patent Documents 2 and 3) has been proposed.

JP 60-158205 A Japanese Patent Publication No. 52-15110 Japanese Patent Laid-Open No. 50-98586

However, when compression molding is performed using the ultrahigh molecular weight polyethylene powder proposed in Patent Document 1, it becomes difficult to uniformly and densely fill the mold. Further, if the particles are too large in gel spinning, extra time and energy are required for melting. If the particle size distribution of the particles is wide in the sintering method, problems such as non-uniform pore size after sintering tend to occur.

In addition, the polyethylene particles obtained by the catalyst systems proposed in Patent Documents 2 and 3 are inferior in powder properties such as a coarse particle size or a wide particle size distribution and a large proportion of fine particles contained in the polymer particles. It was a thing.

Therefore, the present invention has an excellent ultra-high molecular weight polyethylene particles having a narrow particle size distribution and not including coarse particles or fine particles, and further, an excellent powder property having a narrow particle size distribution and not including coarse particles or fine particles. It is an object of the present invention to provide an ultrahigh molecular weight polyethylene which is highly active, has a small amount of catalyst residue, and has no resin coloring in compression molding or powder molding, and a method for producing the same.

As a result of intensive studies to solve the above problems, the present inventors have found that ultrahigh molecular weight polyethylene particles having a specific molecular weight, a molecular weight distribution, an average particle size, and a particle size distribution have a small catalyst residue and are compression molded. The present invention has been completed by finding that the resin is not colored in powder molding and powder molding, and has excellent moldability such as compression molding and powder molding.

That is, the present invention has a viscosity average molecular weight (Mv) of 500,000 to 7,000,000, a weight average molecular weight (Mw) to number average molecular weight (Mn) ratio (Mw/Mn) of 4 to 7 and an average particle diameter. Relates to ultra-high molecular weight polyethylene particles and a method for producing the same, characterized by having a particle diameter of 50 μm or more and 200 μm or less and a standard deviation of particle diameter of 0.2 or less.

The present invention will be described in detail below.

The ultrahigh molecular weight polyethylene particles of the present invention have a viscosity average molecular weight (hereinafter referred to as Mv) of 500,000 to 7,000,000, a weight average molecular weight (hereinafter referred to as Mw) and a number average molecular weight (hereinafter referred to as Mn). The ratio (hereinafter, referred to as Mw/Mn) is 4 or more and 7 or less, the average particle size is 50 μm or more and 200 μm or less, and the standard deviation of the particle size is 0.2 or less.

The ultra-high-molecular-weight polyethylene particles of the present invention include those belonging to the category called polyethylene, such as ethylene homopolymer; ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer. Polymers, ethylene-octene-1 copolymers, ethylene-4-methyl-pentene-1 copolymers and other ethylene-α-olefin copolymers;

The ultrahigh molecular weight polyethylene particles of the present invention have Mv of 500,000 to 7,000,000, and in particular have an excellent balance between molding processability and mechanical properties. Therefore, Mv of 800,000 to 5,000,000 or less. Is preferred. Here, when Mv is less than 500,000, the obtained particles have poor mechanical properties. On the other hand, when Mv exceeds 7 million, the obtained particles have poor moldability. The Mv in the present invention can be obtained by measuring the intrinsic viscosity of the solution measured at 135° C. using the solvent decalin or Uberlord, and calculating the Mv from the viscosity formula shown below.
Ultimate solution viscosity=coefficient K×viscosity average molecular weight Mv×coefficient α
(Coefficient K; 6.20×10 ⁻⁴ , coefficient α; 0.70)
Further, the ultrahigh molecular weight polyethylene particles of the present invention have a molecular weight distribution represented by Mw/Mn of 4 or more and 7 or less, and since they have particularly excellent mechanical properties, they are 4 or more and 6.5 or less. Preferably. Here, when Mw/Mn is less than 4, the obtained particles have poor moldability. On the other hand, when Mw/Mn exceeds 7, the obtained particles have poor mechanical properties. The Mw/Mn in the present invention can be measured by, for example, an elution curve by gel permeation chromatography as a standard polystyrene conversion value.

The ultra-high molecular weight polyethylene particles of the present invention have an average particle size of 50 μm or more and 200 μm or less, and are particularly excellent in compression moldability and solubility in a solvent, and therefore they are 50 μm or more and 180 μm or less. preferable. Here, if the particles have an average particle size of less than 50 μm, the handling property becomes poor. On the other hand, when the particles have an average particle size of more than 200 μm, the moldability becomes poor. The average particle diameter in the present invention can be obtained, for example, by classifying with a sieve and plotting the result on established logarithmic paper to calculate.

The ultrahigh molecular weight polyethylene particles of the present invention have a particle size standard deviation of 0.2 or less. Here, if the standard deviation of the particle size exceeds 0.2, the moldability becomes poor.

Further, the ultrahigh molecular weight polyethylene particles of the present invention are preferably those having a small amount of metal components, since a resin having no coloration is obtained in compression molding or powder molding and a molded product having excellent quality can be obtained. The metal component is based on the metal residue. The content of the metal component can be measured, for example, by forming a plate by compression molding ultrahigh molecular weight polyethylene particles and using a fluorescent X-ray analyzer.

As the method for producing ultrahigh molecular weight polyethylene particles of the present invention, any method can be used as long as it is possible to produce the ultrahigh molecular weight polyethylene particles, for example, a method for polymerizing ethylene using a Ziegler-Natta catalyst. Among them, since it becomes possible to efficiently produce ultra-high molecular weight polyethylene particles with a small catalyst residual, it is possible to use aluminum halide as a component obtained by heating and aging metal magnesium, alcohol and titanium tetraalcoholate. Polymerization temperature 50 to 90 in the presence of a catalyst system consisting of a titanium/magnesium-containing solid catalyst component (A) obtained by reacting a compound with stirring with a Reynolds number of 50,000 or more and an organoaluminum catalyst component (B). The production method is preferably a polymerization method in which ethylene is polymerized at 0° C. and a hydrogen concentration of 0 to 10%.

The titanium/magnesium-containing solid catalyst component (A) is obtained by reacting a component obtained by heating and aging metal magnesium, alcohol, and titanium tetraalcoholate with an aluminum halide compound under stirring with a Reynolds number of 50,000 or more. For its preparation, the method described in, for example, JP-A-50-98586 can be used.

The following are examples of the magnesium metal and the alcohol in that case. Various forms of metallic magnesium, that is, any form such as powder, particles, foil or ribbon can be used. Further, as the alcohol, a straight chain or branched chain aliphatic alcohol having 1 to 18 carbon atoms, an alicyclic alcohol or an aromatic alcohol can be used. Examples of this alcohol include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, n-hexanol, 2-ethylhexanol, n-octanol, i-octanol, n-stearyl alcohol. , Cyclopentanol, cyclohexanol, ethylene glycol and the like. These alcohols are used alone or as a mixture of two or more kinds.

Furthermore, when the titanium/magnesium-containing solid catalyst component (A) is obtained using metallic magnesium, a substance that reacts with metallic magnesium or produces an addition compound, such as iodine, for the purpose of promoting the reaction. It is preferable to add polar substances such as alkyl halides, organic acid esters, and organic acids alone or in combination of two or more.

Examples of the titanium tetra alcoholate include titanium tetraethoxide, titanium tetra-n-propoxide, titanium tetra-i-propoxide, titanium tetra-n-butoxide and the like. Alcoholates having several different hydrocarbon groups may also be used, and these titanium tetraalcoholates may be used alone or as a mixture of two or more kinds.

Preparation of the components obtained by heating and aging metal magnesium and alcohol, titanium tetra alcoholate, for example, powder of metal magnesium, foil, ribbon and alcohol and titanium tetra alcoholate, the molar ratio of metal magnesium and alcohol, the catalytic activity is It is 1:2 to 1:4 because it is possible to obtain a polymerization catalyst having a high powder property and a uniform particle size and excellent in moldability and color suppression. A ratio of 1:2 to 1:2.5 is particularly preferable. Similarly, regarding the molar ratio of magnesium metal and titanium tetraalcoholate, ultra high molecular weight polyethylene particles having high catalytic activity, powder properties, and a polymerization catalyst having a uniform particle size can be obtained, which is excellent in moldability and color suppression. It is preferable that the ratio is 1:0.1 to 1:4.0, and it is particularly preferable to react at a ratio of 1:0.25 to 1:2.0. Further, the reaction of heating and aging is carried out, for example, under reflux or under pressure at a temperature of 50 to 150° C. for 1 to 10 hours, preferably 2 to 6 hours to dissolve metallic magnesium to obtain a uniform liquid substance. This reaction can also be carried out in the presence of an inert solvent such as n-hexane or decane. When iodine is used as a substance that promotes this reaction, iodine can be used in a weight ratio of about 1:0.01 to 0.1 with respect to metallic magnesium.

Next, the titanium/magnesium-containing solid catalyst component (A) can be obtained by reacting the component with an aluminum halide compound under stirring with a Reynolds number of 50,000 or more. At that time, the titanium/magnesium-containing solid catalyst component (A) may be precipitated as a precipitation component.

As the aluminum halide, for example, one represented by the general formula RnAlX _3-n is used. Examples of R in this case include a hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, and examples thereof include a linear or branched alkyl group, a cycloalkyl group, an arylalkyl group, and an aryl group. , And alkylaryl groups. Examples of X include halogen atoms such as chlorine atom, bromine atom and iodine atom, and n represents a number of 0<n<3, preferably 0<n≦2. Further, R is preferably selected from a linear or branched alkyl group, a cycloalkyl group, an arylalkyl group, an aryl group and an alkylaryl group. Specific examples of the aluminum halide compound include dimethyl aluminum chloride, diethyl aluminum chloride, diethyl aluminum bromide, dipropyl aluminum chloride, ethyl aluminum dichloride, i-butyl aluminum dichloride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride, i- Butylaluminum sesquichloride, a mixture of triethylaluminum and aluminum trichloride, etc. may be mentioned.

The amount of aluminum halide is preferably such that the molar ratio of magnesium to aluminum is 1:2 to 1:20, since it is possible to obtain a catalyst having excellent powder properties and catalytic activity. It is particularly preferable to react in an amount of 1:3 to 1:10. The reaction temperature is preferably 100° C. or lower, and particularly preferably in the range of 40 to 70° C., and it is preferable to prepare the titanium/magnesium-containing solid catalyst component (A) over 1 to 6 hours.

The titanium-magnesium-containing solid catalyst component (A) is preferably prepared in a liquid medium, and the liquid medium at that time is preferably a solvent in which an inert organic solvent is present. As the solvent, all those usually used in the art can be used, and examples thereof include aliphatic, alicyclic or aromatic hydrocarbons or halogen derivatives thereof or a mixture thereof, such as isobutane, hexane, heptane and cyclohexane. , Benzene, toluene, xylene, monochlorobenzene and the like are preferably used.

When the aluminum halide compound is reacted with a component obtained by heating and aging metal magnesium, alcohol, and titanium tetraalcoholate to obtain the titanium/magnesium-containing solid catalyst component (A), stirring conditions are important, and high stirring is required. It is necessary to select a condition that gives a stirring Reynolds number of 50,000 or more. Here, the stirring Reynolds number is generally known as one of the indexes showing the degree of stirring. The Reynolds number is a dimensionless number defined by the ratio of the inertial force that tends to move separately from the surroundings due to agitation and the viscous force that tends to move similarly to the surrounding fluid elements. It is a guide for making a decision. When the Reynolds number is low, the flow is laminar, and when the Reynolds number is high, the flow changes from laminar flow to turbulent flow. Here, paying attention to the inertial force and viscous force under stirring, and considering the particles generated by the reaction as spheres, the flow field around the sphere and the sphere surface pressure distribution cause precipitation components to separate and re-adhere, causing stirring. It was found that a titanium/magnesium-containing solid catalyst component (A) having a desired average particle size and particle size distribution is produced under conditions of Reynolds number of 50,000 or more. Furthermore, in the ethylene polymerization by the catalyst using the titanium/magnesium-containing solid catalyst component (A), a replica phenomenon of particles is caused to control the average particle size and particle size distribution of ultrahigh molecular weight polyethylene particles produced. Is possible. That is, the stirring Reynolds number for high stirring is not a mere critical Reynolds number at which turbulent flow starts, but a perfect turbulent condition of 50,000 or more, preferably 50,000 to 1,000,000, particularly preferably 70,000 to 300,000 The reaction is carried out. When the reaction is carried out under a stirring condition of less than 50,000 and a small Reynolds number for stirring, the precipitated component becomes amorphous and has many coarse particles.

The stirring Reynolds number can be calculated by the following formula.
Stirring Reynolds number=fluid density×stirring speed×stirring diameter÷fluid viscosity As the blade shape of the stirrer used for stirring, for example, anchor blades, turbine blades, propeller blades and the like can be used. Paddle blades and ribbon blades may be insufficient to obtain a sufficient stirring Reynolds number.

The titanium/magnesium-containing solid catalyst component (A) is a catalyst system organoaluminum catalyst component (B) without removing remaining unreacted substances and by-products or after removal by filtration or a gradient method. Can be used for the polymerization reaction in the presence of Further, the titanium/magnesium-containing solid catalyst component (A) can be directly subjected to polymerization in a suspended state, but in some cases, it may be separated from the solvent, and further heated under normal pressure or reduced pressure. It is also possible to remove the solvent and use it in a dried state.

The organoaluminum catalyst component (B) which is a catalyst component of the catalyst system may be what is called an organoaluminum compound, and for example, an aluminum compound having a linear or branched alkyl group having 1 to 20 carbon atoms may be used. Specific examples thereof include trimethyl aluminum, triethyl aluminum, tri-i-butyl aluminum, tri-n-butyl aluminum, and tri-n-hexyl aluminum. As the organoaluminum catalyst component (B), an alkyl metal hydride having an alkyl group having 1 to 20 carbon atoms can also be used. Specific examples of such a compound include diisobutylaluminum hydride.

The ultrahigh molecular weight polyethylene particles of the present invention can be produced by using a general reaction equipment of a so-called Ziegler method. That is, polymerization is carried out at a temperature of 20 to 90° C. in a continuous or batch system. The polymerization pressure is not particularly limited, and it is suitable to use under pressure, especially 0.1 to 5 MPa. When the polymerization is carried out in the presence of an inert solvent, any of those usually used as an inert solvent can be used. Particularly suitable are alkanes or cycloalkanes having 4 to 20 carbon atoms, such as isobutane, pentane, hexane, cyclohexane and the like. As the reactor used in the polymerization step, any reactor normally used in the technical field such as a stirring tank type stirring device can be appropriately used. When the stirring tank type stirrer is used, various types of stirrers such as an Ikari type stirrer, a screw type stirrer, and a ribbon type stirrer can be used as the stirrer.

The amount of the titanium/magnesium-containing solid catalyst component (A) used in producing the ultrahigh molecular weight polyethylene particles of the present invention is usually 0.001 to 2.5 titanium atoms per liter of solvent or reactor. It is preferable to use in an amount corresponding to millimolar, and higher concentration can be used depending on the conditions. Further, the organoaluminum catalyst component (B) is preferably 0.02 to 50 mmol, and particularly preferably 0.2 to 5 mmol, per 1 liter of the solvent or 1 liter of the reactor.

When the ultrahigh molecular weight polyethylene particles of the present invention are produced, the molecular weight thereof can be adjusted by a method in which an appropriate amount of hydrogen is present in the reaction system. Further, since it becomes possible to efficiently produce an ultrahigh molecular weight polyethylene having a viscosity average molecular weight of 500,000 or more and 7,000,000 or less, it is preferable that the hydrogen concentration is 0 to 10% with respect to ethylene.

The present invention has a high Mv of 500,000 to 7,000,000, a Mw/Mn of 4 to 7 and a molecular weight distribution suitable for molding, an average particle size of 50 μm to 200 μm, and a standard deviation of particle sizes of 0. (EN) An ultra high molecular weight polyethylene particle excellent in powder characteristics of 2 or less and a manufacturing method suitable for manufacturing the same.

Hereinafter, the present invention will be shown by examples, but the present invention is not limited to these examples.

The evaluations in Examples and Comparative Examples were carried out by the following methods.

~Catalytic activity~
The catalytic activity is represented by the polymer production amount (g) per 1 g of the titanium/magnesium-containing solid catalyst component (A).

~ Intrinsic viscosity, viscosity average molecular weight ~
The intrinsic viscosity of the solution was measured at 135° C. using the solvents decalin and Uberlord, and Mv was determined by the viscosity formula shown below.
Ultimate solution viscosity=coefficient K×viscosity average molecular weight Mv×coefficient α
(Coefficient K; 6.20×10 ⁻⁴ , coefficient α; 0.70)
~ Weight average molecular weight (Mw), number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) ~
It was measured by gel permeation chromatography (GPC). A (trade name) 150C ALC/GPC (manufactured by Waters) is used as the GPC device, (trade name) GMH-HR-H(S) (manufactured by Tosoh Corporation) is used as the column, and the column temperature is 145°C. And 1-chloronaphthalene was used as an eluent. A measurement sample was prepared at a concentration of 0.08 mg/milliliter, and 200 microliters was injected to measure. The calibration curve of the molecular weight is calibrated by a universal calibration method using a polystyrene sample having a known molecular weight (absolute molecular weight=2600 to 8640000).

~ Average particle size and standard deviation ~
The obtained ultra-high molecular weight polyethylene particles were classified by a sieve of JIS Z-8801 (opening of 1000 to 75 μm), and the classification results were plotted by plotting the particle size on the horizontal axis of the probability logarithmic paper and the cumulative weight value on the vertical axis. An approximate straight line was calculated and obtained by the multiplication method. Specifically, the particle size for the weight cumulative value of 50% is the average particle size, and the logarithmic value of the ratio of the particle size to the average particle size for the weight cumulative value of 84% is the standard deviation. The ratio (% by weight) of polymer particles having a particle size of more than 400 μm is shown.

~ Impact strength ~
Impact strength measurement test pieces were prepared by compression molding using the obtained ultra high molecular weight polyethylene particles, and the impact strength was measured using a Charpy impact tester. The measurement conditions were in accordance with JIS K6936-2.

Example 1
(Preparation of titanium/magnesium-containing solid catalyst component (A1))
A 1000 ml glass flask equipped with a stirrer was charged with 8.0 g (0.33 mol) of metallic magnesium powder and 45 g (0.13 mol) of titanium tetrabutoxide, and 52 g (0 g of 0-n-butanol dissolved with 0.4 g of iodine). 0.7 mol) was added at 90° C. over 2 hours, and metallic magnesium was dissolved by stirring under nitrogen blanketing at 140° C. for 2 hours while removing generated hydrogen gas. Then, 560 ml of hexane was added to obtain 680 ml of a homogeneous solution. The density of this solution was 0.695 kg/m ³ , and the viscosity coefficient was 0.60 cP, and these values were used when calculating the stirring Reynolds number.

100 ml of this homogeneous solution (containing 0.048 mol as a magnesium component) was transferred to a separately prepared 500 ml glass flask (0.1 m in diameter) equipped with a stirrer, the stirring speed was 400 rpm, the stirring Reynolds number was 77,000, and i at 45°C. 107 ml of a hexane solution containing 0.29 mol of -butylaluminum dichloride was added, and the mixture was further stirred at 60°C for 1 hour to generate particles. Then, the remaining unreacted materials and by-products were removed by a gradient method using hexane to obtain a titanium/magnesium-containing solid catalyst component (A1). When the composition was analyzed by an inductively coupled plasma emission spectroscopic analyzer, the titanium content was 8.6 wt %.

(Production of ultra high molecular weight polyethylene particles)
The inside of the stainless steel electromagnetic stirring autoclave having an internal volume of 2 liters was sufficiently replaced with nitrogen, 1.2 liters of hexane was charged, and the internal temperature was adjusted to 65°C. Thereafter, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 10.3 mg of the titanium/magnesium-containing solid catalyst component (A1) obtained above was sequentially added. did. After adjusting the internal pressure of the autoclave to 0.08 MPaG, polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.8 MPaG. After completion of the polymerization, the reaction mixture was cooled, unreacted gas was purged to collect ultra-high molecular weight polyethylene, separated from the solvent by filtration and dried.

As a result, 310 g of ultra-high molecular weight polyethylene particles having a bulk density of 0.33 g/cm ³ were obtained. The production amount (hereinafter referred to as activity) per 1 g of the titanium/magnesium-containing solid catalyst component (A1) corresponds to 30,000 g/g, and the amount of titanium remaining in the ultrahigh molecular weight polyethylene particles measured by a fluorescent X-ray analyzer is It was 2.8 ppm. The average particle size was 150 μm, the ratio of coarse particles having a particle size of 400 μm or more (hereinafter referred to as coarse particles) was 0.0% by weight, and σ was 0.18.

Moreover, Mv of the obtained ultra high molecular weight polyethylene particles was 3.8 million, and Mw/Mn was 5.4. The Charpy impact strength was 80 KJ/m ² .

Comparative Example 1
(Titanium/magnesium-containing solid catalyst component (a1))
A titanium/magnesium-containing solid catalyst component (B1) was obtained in the same manner as in Example 1 except that the stirring was performed so that the Reynolds number was 19000. That is, 100 ml of the homogeneous solution obtained in Example 1 was placed in a separately prepared 500 ml glass flask, 107 ml of a hexane solution containing 0.29 mol of i-butylaluminum dichloride at 45° C. at a stirring speed of 100 rpm and a Reynolds number of 19000. In addition, the mixture was further stirred at 60° C. for 1 hour to generate particles. Then, using hexane, the unreacted materials and byproducts that remained were removed by a gradient method to obtain a titanium/magnesium-containing solid catalyst component (a1). When the composition was analyzed by an inductively coupled plasma emission spectroscopic analyzer, the titanium content was 8.8 wt %.

(Production of polyethylene)
Polymerization of ethylene was carried out in the same manner as in Example 1. That is, the inside of a 2-liter autoclave was sufficiently replaced with nitrogen, 1.2 liters of hexane was charged, and the internal temperature was adjusted to 65°C. Then, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 11.2 mg of the titanium-magnesium-containing solid catalyst component (a1) obtained above was sequentially added. did. After adjusting the internal pressure of the autoclave to 0.08 MPaG, polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.8 MPaG. After completion of the polymerization, the mixture was cooled, unreacted gas was purged to collect polyethylene, and the polyethylene was separated from the solvent by filtration and dried.

As a result, 246 g of polyethylene having a bulk density of 0.34 g/cm ³ was obtained. The activity was equivalent to 22000 g/g, and the titanium remaining amount in polyethylene measured by a fluorescent X-ray analyzer was 4.0 ppm. Further, the average particle diameter was 280 μm, the ratio of coarse particles was 33% by weight, and σ was 0.68, and the powder properties were poor.

Comparative example 2
(Preparation of titanium/magnesium-containing solid catalyst component (a2))
A titanium/magnesium-containing solid catalyst component (a2) was obtained in the same manner as in Example 1 except that the stirring Reynolds number was 39000. That is, 100 ml of the homogeneous solution obtained in Example 1 was placed in a separately prepared 500 ml glass flask, 106 ml of a hexane solution containing 0.29 mol of i-butylaluminum dichloride at 45° C. at a stirring speed of 200 rpm and a stirring Reynolds number of 39000. In addition, the mixture was further stirred at 60° C. for 1 hour to generate particles. Then, the remaining unreacted materials and byproducts were removed by a gradient method using hexane to obtain a titanium/magnesium-containing solid catalyst component (a2). When the composition was analyzed by an inductively coupled plasma emission spectroscopic analyzer, the titanium content was 8.8 wt %.

(Production of polyethylene)
Polyethylene was polymerized in the same manner as in Example 1. That is, the inside of a 2 liter autoclave was sufficiently replaced with nitrogen, 1.2 liter of hexane was charged, and the internal temperature was adjusted to 65°C. Thereafter, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 10.8 mg of the titanium-magnesium-containing solid catalyst component (a2) obtained above was sequentially added. did. After adjusting the internal pressure of the autoclave to 0.08 MPaG, polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.8 MPaG. After the completion of the polymerization, the mixture was cooled, unreacted gas was purged to recover polyethylene, and the polyethylene was separated from the solvent by filtration and dried.

As a result, 270 g of polyethylene having a bulk density of 0.36 g/cm ³ was obtained. The activity was equivalent to 25000 g/g, and the titanium remaining amount in polyethylene measured by a fluorescent X-ray analyzer was 3.5 ppm. Further, the average particle size was 210 μm, the ratio of coarse particles was 25% by weight, and σ was 0.50, and the powder properties were poor.

Example 2
(Solid catalyst component containing titanium/magnesium (A2)
A titanium/magnesium-containing solid catalyst component (A2) was obtained in the same manner as in Example 1 except that the stirring Reynolds number was 116000. That is, 100 mlg of the homogeneous solution obtained in Example 1 (containing 0.048 mol as a magnesium component) was placed in a separately prepared 500 ml glass flask, the stirring speed was 600 rpm, the stirring Reynolds number was 116000, and i-butylaluminum dichloride was added at 45°C. 106 ml of a hexane solution containing 0.29 mol was added, and the mixture was further stirred at 60° C. for 1 hour to generate particles. Then, the remaining unreacted materials and by-products were removed by a gradient method using hexane to obtain a titanium/magnesium-containing solid catalyst component (A2). When the composition was analyzed by an inductively coupled plasma emission spectroscopic analyzer, the titanium content was 8.5 wt %.

(Production of ultra high molecular weight polyethylene particles)
Ultra-high molecular weight polyethylene particles were produced in the same manner as in Example 1. That is, the inside of a 2 liter autoclave was sufficiently replaced with nitrogen, 1.2 liter of hexane was charged, and the internal temperature was adjusted to 65°C. Thereafter, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 9.8 mg of the titanium/magnesium-containing solid catalyst component (A2) obtained above was sequentially added. did. After adjusting the internal pressure of the autoclave to 0.08 MPaG, polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.8 MPaG. After completion of the polymerization, the mixture was cooled, unreacted gas was purged to collect ultra-high molecular weight polyethylene particles, separated from the solvent by filtration and dried.

As a result, 304 g of ultra-high molecular weight polyethylene particles having a bulk density of 0.34 g/cm ³ were obtained. The activity was equivalent to 31000 g/g, and the amount of titanium remaining in the ultrahigh molecular weight polyethylene particles measured by a fluorescent X-ray analyzer was 2.7 ppm. Further, the average particle size was 120 μm, the ratio of coarse particles was 0% by weight, and σ was 0.16, and the powder properties were good.

The ultra high molecular weight polyethylene particles obtained had Mv of 4.1 million and Mw/Mn of 5.6. The Charpy impact strength was 80 KJ/m ² .

Example 3
(Titanium/magnesium-containing solid catalyst component (A3))
A titanium/magnesium-containing solid catalyst component (A3) was obtained in the same manner as in Example 1 except that ethylaluminum chloride was used instead of i-butylaluminum dichloride, and the stirring Reynolds number was 232000. That is, 100 mlg of the homogeneous solution obtained in Example 1 (containing 0.048 mol as a magnesium component) was placed in a separately prepared 500 ml stainless steel container (stirring diameter 0.1 m), the stirring speed was 1200 rpm, and the stirring Reynolds number was 232000. 40 ml of a hexane solution containing 0.19 mol of ethyl aluminum chloride was added at 45° C., and the mixture was further stirred at 60° C. for 1 hour to generate particles. Next, hexane was used to remove the unreacted substances and by-products remaining by a gradient method to obtain a titanium/magnesium-containing solid catalyst component (A3). When the composition was analyzed by an inductively coupled plasma emission spectroscopic analyzer, the titanium content was 9.5 wt %.

(Production of ultra high molecular weight polyethylene particles)
Ultra-high molecular weight polyethylene particles were produced in the same manner as in Example 1. That is, the inside of a 2 liter autoclave was sufficiently replaced with nitrogen, 1.2 liter of hexane was charged, and the internal temperature was adjusted to 65°C. Then, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 10.5 mg of the titanium-magnesium-containing solid catalyst component (A3) obtained above was sequentially added. did. After adjusting the internal pressure of the autoclave to 0.08 MPaG, polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.8 MPaG. After completion of the polymerization, the mixture was cooled, unreacted gas was purged to collect ultra-high molecular weight polyethylene particles, separated from the solvent by filtration and dried.

As a result, 289 g of ultra high molecular weight polyethylene particles having a bulk density of 0.35 g/cm ³ were obtained. The activity was equivalent to 27500 g/g, and the amount of titanium remaining in the ultrahigh molecular weight polyethylene particles measured by a fluorescent X-ray analyzer was 3.5 ppm. The average particle size was 100 μm, the ratio of coarse particles was 0% by weight, and σ was 0.12. The powder properties were good.

Moreover, Mv of the obtained ultra-high molecular weight polyethylene particles was 2.5 million and Mw/Mn was 5.2. The Charpy impact strength was 90 KJ/m ² , which was a very high result.

Example 4
(Solid catalyst component containing titanium/magnesium (A4)
A 1000 ml glass flask equipped with a stirrer was charged with 8.0 g (0.33 mol) of metallic magnesium powder and 224 g (0.66 mol) of titanium tetrabutoxide, and 52 g (0 of n-butanol) in which 0.4 g of iodine was dissolved. 0.7 mol) was added at 90° C. over 2 hours, and metallic magnesium was dissolved by stirring under nitrogen blanketing at 140° C. for 2 hours while removing generated hydrogen gas. Then, 560 ml of hexane was added to obtain 860 ml of a homogeneous solution. The density of this solution was 0.76 kg/m ³ , and the viscosity coefficient was 0.68 cP, and these values were used when calculating the stirring Reynolds number.

100 ml of this homogeneous solution (containing 0.038 mol as a magnesium component) was transferred to a separately prepared 500 ml glass flask equipped with a stirrer, the stirring speed was 400 rpm, and the stirring Reynolds number was 75000. At 45° C., ethyl aluminum dichloride 0.19 mol was added. 40 ml of a hexane solution containing was added and further stirred at 60° C. for 1 hour to generate particles. Then, the remaining unreacted materials and byproducts were removed by a gradient method using hexane to obtain a titanium/magnesium-containing solid catalyst component (A4). When the composition was analyzed by an inductively coupled plasma emission spectroscopic analyzer, the titanium content was 14.8 wt %.

(Production of ultra high molecular weight polyethylene particles)
The interior of the stainless steel electromagnetic stirring type autoclave having an internal volume of 2 liters was sufficiently replaced with nitrogen, 1.2 liters of hexane was charged, and the internal temperature was adjusted to 65°C. Then, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 15.3 mg of the titanium-magnesium-containing solid catalyst component (A4) obtained above was sequentially added. did. After adjusting the internal pressure of the autoclave to 0.08 MPaG, polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.8 MPaG. After the completion of the polymerization, the mixture was cooled, unreacted gas was purged, ultra high molecular weight polyethylene particles were collected, separated from the solvent by filtration and dried.

As a result, 260 g of ultrahigh molecular weight polyethylene particles having a bulk density of 0.38 g/cm ³ were obtained. The activity was equivalent to 17,000 g/g, and the amount of titanium remaining in the ultrahigh molecular weight polyethylene particles measured by a fluorescent X-ray analyzer was 9.0 ppm. The average particle size was 190 μm, the ratio of coarse particles was 0.0% by weight, and σ was 0.19.

The obtained ultra high molecular weight polyethylene particles had Mv of 2.1 million and Mw/Mn of 5.6. The Charpy impact strength was 90 KJ/m ² , which was a very high result.

Example 5
(Titanium/magnesium-containing solid catalyst component (A5))
A 1000 ml glass flask equipped with a stirrer was charged with 8.0 g (0.33 mol) of metallic magnesium powder and 45 g (0.13 mol) of titanium tetrabutoxide, and 71 g (0 g of 0-n-hexanol dissolved with 0.4 g of iodine). 0.7 mol) was added at 90° C. over 2 hours, and metallic magnesium was dissolved by stirring under nitrogen blanketing at 140° C. for 2 hours while removing generated hydrogen gas. Then, 560 ml of hexane was added to obtain 690 ml of a homogeneous solution. The density of this solution was 0.72 kg/m 3, and the viscosity coefficient was 0.64 cP, and these values were used when calculating the stirring Reynolds number.

100 ml of this homogeneous solution (containing 0.048 mol as a magnesium component) was transferred to a separately prepared 500 ml glass flask equipped with a stirrer, the stirring speed was 400 rpm, the stirring Reynolds number was 75000, and i-butylaluminum dichloride was added at 45°C. 106 ml of a hexane solution containing 29 mol was added, and the mixture was further stirred at 60° C. for 1 hour to generate particles. Then, the remaining unreacted materials and byproducts were removed by a gradient method using hexane to obtain a titanium/magnesium-containing solid catalyst component (A5). When the composition was analyzed by an inductively coupled plasma emission spectroscopic analyzer, the titanium content was 9.1 wt %.

(Production of ultra high molecular weight polyethylene particles)
The interior of the stainless steel electromagnetic stirring type autoclave having an internal volume of 2 liters was sufficiently replaced with nitrogen, 1.2 liters of hexane was charged, and the internal temperature was adjusted to 65°C. Then, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 10.3 mg of the titanium/magnesium-containing solid catalyst component (A5) obtained above was sequentially added. did. After adjusting the internal pressure of the autoclave to 0.08 MPaG, polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.8 MPaG. After the completion of the polymerization, the mixture was cooled, unreacted gas was purged, ultra high molecular weight polyethylene particles were collected, separated from the solvent by filtration and dried.

As a result, 258 g of ultrahigh molecular weight polyethylene particles having a bulk density of 0.35 g/cm ³ were obtained. The activity was equivalent to 25000 g/g, and the amount of titanium remaining in the ultrahigh molecular weight polyethylene particles measured by a fluorescent X-ray analyzer was 3.6 ppm. The average particle size was 160 μm, the ratio of coarse particles was 0.0% by weight, and σ was 0.17.

The ultra high molecular weight polyethylene particles obtained had Mv of 4.1 million and Mw/Mn of 5.6. The Charpy impact strength was 80 KJ/m ² .

Example 6
Using the titanium/magnesium-containing solid catalyst component (A1) prepared in Example 1, ultrahigh molecular weight polyethylene particles were produced using hydrogen as a molecular weight modifier.

That is, the inside of a stainless steel electromagnetic stirring autoclave having an internal volume of 2 liters was sufficiently replaced with nitrogen, 1.2 liters of hexane was charged, and the internal temperature was adjusted to 65°C. Thereafter, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 9.8 mg of the titanium/magnesium-containing solid catalyst component (A1) was sequentially added. After adjusting the internal pressure of the autoclave to 0.08 MPaG, 0.04 MPa of hydrogen was added, and polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.9 MPaG. The hydrogen concentration corresponded to 4.9%. After completion of the polymerization, the mixture was cooled, unreacted gas was purged to collect ultra-high molecular weight polyethylene particles, separated from the solvent by filtration and dried.

As a result, 274 g of ultra high molecular weight polyethylene particles having a bulk density of 0.33 g/cm ³ were obtained. The activity was equivalent to 28,000 g/g, and the amount of titanium remaining in the ultrahigh molecular weight polyethylene particles measured by a fluorescent X-ray analyzer was 3.0 ppm. The average particle size was 150 μm, the ratio of coarse particles was 0.0% by weight, and σ was 0.18.

The ultra high molecular weight polyethylene particles obtained had Mv of 1.2 million and Mw/Mn of 5.6. The Charpy impact strength was 70 KJ/m ² .

Example 7
Using the titanium/magnesium-containing solid catalyst component (A1) prepared in Example 1, hydrogen was used as a molecular weight modifier in a larger amount than in Example 6 to produce ultra high molecular weight polyethylene particles.

That is, the inside of a stainless steel electromagnetic stirring autoclave having an internal volume of 2 liters was sufficiently replaced with nitrogen, 1.2 liters of hexane was charged, and the internal temperature was adjusted to 70°C. Thereafter, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as the organoaluminum catalyst component (B) and 10.1 mg of the titanium/magnesium-containing solid catalyst component (A1) was sequentially added. After adjusting the internal pressure of the autoclave to 0.08 MPaG, hydrogen was added at 0.08 MPa, and polymerization was carried out for 2 hours while continuously adding ethylene so that the internal pressure of the autoclave became 0.98 MPaG. The hydrogen concentration corresponded to 8.7%. After completion of the polymerization, the mixture was cooled, unreacted gas was purged to collect ultra high molecular weight polyethylene particles, and the ultra high molecular weight polyethylene particles were separated from the solvent by filtration and dried.

As a result, 273 g of ultrahigh molecular weight polyethylene particles having a bulk density of 0.33 g/cm ³ were obtained. The activity was equivalent to 27,000 g/g, and the amount of titanium remaining in the ultrahigh molecular weight polyethylene particles measured by a fluorescent X-ray analyzer was 3.2 ppm. The average particle size was 150 μm, the ratio of coarse particles was 0.0% by weight, and σ was 0.18.

The obtained ultra high molecular weight polyethylene particles had an Mv of 550,000 and an Mw/Mn of 5.6. The Charpy impact strength was 65 KJ/m ² .

Comparative Example 3
Using the titanium/magnesium-containing solid catalyst component (A1) prepared in Example 1, more hydrogen was used as a molecular weight modifier than in Example 7 to produce polyethylene particles.

That is, the interior of a stainless steel electromagnetic stirring autoclave having an internal volume of 2 liters was sufficiently replaced with nitrogen, 1.2 liters of hexane was charged, and the internal temperature was adjusted to 80°C. Then, a slurry containing 0.23 g (1.2 mmol) of tri-i-butylaluminum as an organoaluminum catalyst component (B) and 8.8 mg of a titanium/magnesium-containing solid catalyst component (A1) was sequentially added. After adjusting the internal pressure of the autoclave to 0.08 MPaG, 0.4 MPa of hydrogen was added, and polymerization was carried out for 90 minutes while continuously adding ethylene so that the internal pressure of the autoclave was 1.1 MPaG. After completion of the polymerization, the mixture was cooled, unreacted gas was purged to take out polyethylene particles, separated from the solvent by filtration and dried.

As a result, 229 g of polyethylene particles having a bulk density of 0.33 g/cm ³ were obtained. The activity was equivalent to 26000 g/g, and the amount of titanium remaining in the polyethylene particles measured by a fluorescent X-ray analyzer was 3.3 ppm. The average particle size was 140 μm, the ratio of coarse particles was 0.0% by weight, and σ was 0.18.

The obtained polyethylene particles had an Mv of 52,000 and an Mw/Mn of 5.8. The Charpy impact strength was 6 KJ/m ² , which was extremely low.

The present invention has a high Mv of 500,000 to 7,000,000, a Mw/Mn of 4 to 7 and a molecular weight distribution suitable for molding, an average particle size of 50 μm to 200 μm, and a standard deviation of particle sizes of 0. The present invention provides an ultra-high molecular weight polyethylene particle excellent in powder characteristics of 2 or less and a production method suitable for producing the same. The ultra-high molecular weight polyethylene particle of the present invention is excellent in moldability and mechanical properties and is colored. It becomes possible to provide a compression-molded body and a powder-molded body that do not have such a property, and the industrial applicability is high.

Claims (1)

The viscosity average molecular weight (Mv) is 500,000 or more and 7,000,000 or less, the ratio (Mw/Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) is 4 or more and 7 or less, and the average particle diameter is 50 μm or more and 200 μm or less, When producing ultra-high molecular weight polyethylene particles having a standard deviation of particle diameter of 0.2 or less , (A) agitating aluminum halide compound with a component obtained by heating and aging metal magnesium, alcohol, and titanium tetraalcoholate Reynolds number Polymerization temperature 50 to 90° C., hydrogen concentration 0 to 10% in the presence of a catalyst system comprising a titanium/magnesium-containing solid catalyst component obtained by reaction under stirring of 50,000 or more and (B) an organoaluminum catalyst component. A method for producing ultrahigh molecular weight polyethylene particles, characterized in that ethylene is polymerized .