JP6889621B2 - Method for producing core-shell mesoporous silica for polymerization catalyst carrier and olefin polymer - Google Patents

Description

The present invention relates to a core-shell mesoporous silica for a polymerization catalyst carrier and a method for producing an olefin polymer.

In recent years, the demands on the physical properties of polymers have diversified, and polymers having various properties are desired.

As a method for producing a polymer, a method of carrying a polymerization catalyst on various carriers and polymerizing is generally used. In this case, the shape and morphology of the polymer produced by the carrier used and the method of carrying the polymer are controlled. Can be done.

For example, as a method for producing polyethylene, a method of polymerizing ethylene using a catalyst in which titanocene dichloride is supported on mesoporous silica has been proposed (for example, Non-Patent Document 1). This document describes that this method can produce a polymer having a high molecular weight and high crystallinity.

Science, Vol.285,1999,2113

In the method described in Non-Patent Document 1, it is considered that the polymerization proceeds in a spatially restricted environment such as in pores having a diameter of several nm, so that side reactions and entanglement of molecular chains are suppressed. .. However, in the conventional mesoporous silica represented by MCM-41 as in Non-Patent Document 1, for example, as shown in the schematic diagram shown on the left of FIG. 1, the pores arranged in a honeycomb shape are formed on the particle surface. It is open in one or multiple directions and has a flat surface with no pore openings. Therefore, many catalysts are supported not only in the pores but also on the surface of the particles, and a high-molecular-weight and highly crystalline polymer is produced from the catalyst supported in the pores, while the catalyst is supported in other than the pores. There is a problem that a polymer having a low molecular weight and low crystallinity is also produced from the catalyst. Further, when polymerizing is carried out by catalyst-supporting conventional mesoporous silica represented by MCM-41, the portion where the pores arranged in a honeycomb shape in one direction are open with respect to the particle surface is polymerized in the pores. The problem is that the polymer chains extending outside the pores are polymerized in the nearby pores and entangled with the polymer chains extending outside the pores, resulting in reduced crystallinity and the polymer chains becoming lumps of about several cm. There is also. Further, the conventional mesoporous silica represented by MCM-41 has long pores like a straw, and the monomer does not reach the catalyst supported in the back of the pores, so that it cannot be used for polymerization, so that catalyst loss occurs. There is also the problem of being large.

Therefore, according to the present invention, when used for a polymerization catalyst carrier, a homogeneous polymer having a high molecular weight and a high crystallinity (for example, a powdery polymer) can be obtained, and the catalyst loss can be reduced. It is intended to provide silica.

As a result of diligent studies to solve the above problems, the present inventors have determined that in a core-shell type mesoporous silica having a core portion and a shell portion, the core portion has no pores and a specific mesoporous structure is formed in the shell portion. We have found that the above problems can be solved, and have completed the present invention.

That is, the present invention is as follows.
[1]
A core-shell type having a core part and a shell part,
A core-shell type mesoporous silica for a polymerization catalyst carrier, wherein the core portion has no pores, and the shell portion has a mesoporous structure in which pores are arranged radially from the surface of the core portion to the surface of the shell portion.
[2]
The core-shell type mesoporous silica for a polymerization catalyst carrier according to the above item [1], which has an average primary particle size of 0.1 to 10 μm.
[3]
The core-shell type mesoporous silica for a polymerization catalyst carrier according to the above item [1] or [2], wherein the thickness of the shell portion is 500 nm or less.
[4]
The core-shell mesoporous silica for a polymerization catalyst carrier according to any one of the above items [1] to [3], wherein the ratio of the hydrophilic surface area to the total specific surface area is 40% or less.
[5]
The core-shell type mesoporous silica according to any one of [1] to [4], which carries a polymerization catalyst for olefins.
[6]
The core-shell mesoporous silica according to the previous item [5], wherein the polymerization catalyst for olefins contains a metallocene compound.
[7]
A method for producing an olefin polymer using a core-shell type mesoporous silica carrying the polymerization catalyst for olefin according to the above item [5] or [6].

According to the present invention, since pores are opened on the entire surface of silica particles, when used as a polymerization catalyst carrier, a homogeneous polymer having a high molecular weight and a high degree of crystallization (for example, a powdery polymer) can be obtained. It is possible to provide mesoporous silica for a polymerization catalyst carrier which can reduce catalyst loss.

It is a schematic diagram of a typical mesoporous silica (MCM-41) and the mesoporous silica of the present invention, the schematic diagram of the MCM-41 is shown in the left figure, and the schematic diagram of the mesoporous silica of the present invention is shown in the right figure.

Hereinafter, embodiments for carrying out the present invention (hereinafter, simply referred to as “the present embodiment”) will be described in detail. The present embodiment is an example for explaining the present invention, and the present invention is not limited to the embodiment. That is, the present invention can be variously modified without departing from the gist thereof.

[Core-shell type mesoporous silica]
The mesoporous silica having the core-shell structure of the present embodiment (hereinafter, referred to as “core-shell type mesoporous silica” or simply “mesoporous silica”) has, for example, a core portion having no pore structure, that is, a non-pore structure. Yes, the shell portion (outer shell portion) is a spherical particle having a mesoporous structure arranged radially from the surface of the core portion to the surface of the shell portion, for example, as shown in the schematic diagram shown on the right side of FIG. .. The mesoporous silica of the present embodiment has no pores in the core portion and forms the above-mentioned mesoporous structure in the shell portion, so that when used as a polymerization catalyst carrier, a homogeneous polymer having a high molecular weight and a high crystallinity can be obtained. And the catalyst loss can be reduced. The fact that the core portion has no pores can be determined by the fact that no pores can be seen with a transmission electron microscope (TEM).

The average primary particle size of the mesoporous silica of the present embodiment is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and even more preferably 0.1 to 3 μm. If the average primary particle size is less than 0.1 μm, it tends to fly into the air during handling, which may cause handling problems. If the average primary particle size exceeds 5 μm, fish eyes and the like are formed during polymer molding. It may cause defects. The average primary particle size can be measured with a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

The mesoporous silica of the present embodiment has, for example, one or more peaks at a diffraction angle (2θ) corresponding to a crystal lattice plane spacing (d) = 2 to 12 nm in a powder X-ray diffraction (XRD) measurement pattern. Have. This peak means that the material has regular periodicity in the meso region.

The average primary particle size of the mesoporous silica of the present embodiment, the degree of distribution thereof, and the thickness of the shell portion (outer shell portion) can be measured by observing TEM or SEM. Specifically, under TEM observation, the diameter and outer shell thickness of all the particles in the visual field including 20 to 30 particles are actually measured on a photograph. This operation is performed by changing the field of view five times. From the obtained data, the average primary particle size, the degree of distribution thereof, and the thickness of the shell portion (outer shell portion) are obtained. The magnification at the time of TEM observation may be, for example, about 10,000 to 100,000 times, and may be appropriately adjusted depending on the size of the particles.

(Shell part (outer shell part) of core-shell type mesoporous silica)
The thickness of the shell portion (outer shell portion) of the mesoporous silica of the present embodiment is an average thickness represented by a number average, preferably 500 nm or less, more preferably 5 to 500 nm, and 5 to 300 nm. It is more preferably 5 to 100 nm. When the thickness of the shell portion is 500 nm or less, the catalyst supported in the back of the pores also comes into contact with the monomer and contributes to the reaction, so that the catalyst loss tends to be further reduced.

(Pores in the outer shell of core-shell mesoporous silica)
The pore diameter of the pores of the shell portion (outer shell portion) of the mesoporous silica of the present embodiment may be appropriately selected depending on the size of the catalyst to be supported, but is preferably 5 times or less, more preferably 1 with respect to the major axis of the catalyst. It is ~ 5 times, more preferably 2 to 4 times. If the pore diameter of the pores in the shell portion is smaller than 1 times the major axis of the catalyst, the catalyst may not easily penetrate into the pores, and the pore diameter of the pores in the shell portion is larger than 5 times the major axis of the catalyst. If it is large, the reaction field of the polymerization is less likely to be spatially restricted, and the effect of polymerization in the pores may be less likely to be obtained. The size of the catalyst to be supported can be obtained by calculation by computer simulation described later. The pore size of the pores can be calculated by analyzing the nitrogen adsorption isotherm obtained from the nitrogen adsorption test by the BHJ method. Further, the length of the pores and the thickness of the shell portion (outer shell portion) may be considered to be the same, and the length of the pores is preferably 500 nm or less, more preferably 5 to 500 nm, and 10 It is more preferably ~ 300 nm.

The calculation of the catalyst size may be performed, for example, in the following procedures (a) to (d).
(A) A molecular dynamics simulation is performed for each catalyst.
(B) The structures of 100 to 5000 are taken out, and each structure is approximated to an ellipsoid according to the principal moment of inertia.
(C) The maximum interatomic distance of each structure is taken as the major axis of the ellipsoid, and the size of the ellipsoid consisting of the major axis, the minor axis, and the height is defined.
(D) Each component (major axis, minor axis, and height) of the ellipsoid is simply averaged for all structures, and this is taken as the size of the catalyst.

(Ratio of hydrophilic surface area of core-shell mesoporous silica)
The ratio of the hydrophilic surface area to the total specific surface area of the mesoporous silica of the present embodiment is preferably 40% or less, more preferably 30% or less, still more preferably 10% or less. The "hydrophilic surface area ratio" as used herein refers to the ratio of the specific surface area obtained from the water vapor adsorption test to the specific surface area of the mesoporous silica of the present embodiment obtained from the nitrogen adsorption test. If the ratio of the hydrophilic surface area is too large, the catalyst is inactivated by water or a hydrophilic substance on the particle surface and acts as a chain transfer agent for polymerization, so that a polymer having a low molecular weight is easily produced and the catalyst loss is large. There is a risk of becoming.

(Metal concentration of core-shell mesoporous silica)
The concentration of metals other than the main components constituting the particles in the mesoporous silica of the present embodiment is preferably 500 ppm or less, more preferably 100 ppm or less. If the metal concentration exceeds 500 ppm, the metal tends to deactivate the catalyst, which may increase the catalyst loss. Examples of the metal include Cr, Mn, Sr, Zn, Ba, Al, B, Nb, Zr, Na, Mg, V, P, K, Fe, Ca, and Ti. The metal concentration can be calculated by analyzing with an ICP emission spectrometer.

(Ratio of outer specific surface area of core-shell mesoporous silica)
The mesoporous silica of the present embodiment is, for example, spherical particles in which pores are arranged radially from the surface of the core portion to the surface of the shell portion, and has the smallest surface area other than the pores. The ratio of the specific surface area other than the inside of the pores to the specific surface area of the entire silica particles is preferably 30% or less, more preferably 20% or less, still more preferably 10% or less. The ratio of the specific surface area other than the inside of the pores to the specific surface area of the entire particle can be calculated by analyzing the adsorption isotherm obtained from the nitrogen adsorption / desorption test and the desorption isotherm by the t-plot method.

[Manufacturing method of mesoporous silica]
Hereinafter, a preferred embodiment of the method for producing mesoporous silica of the present embodiment will be described.

A suitable method for producing the mesoporous silica of the present embodiment includes, for example, the following steps (a) to (e).
(A) A step of dispersing substantially non-porous core particles in a basic aqueous solution to prepare a dispersion liquid, and heating and stirring to dissolve the particle surface.
(B) A step of adding a surfactant, water and alcohol to the dispersion obtained in (a) and mixing them.
(C) A silica raw material is added to the mixed dispersion obtained in (b), the silica raw material is reacted in the dispersion under the conditions of pH 8 to 13, and silica and a surfactant are applied to the surface of the silica core particles. The step of forming the containing shell precursor.
(D) A step of removing a surfactant from a shell precursor to form a shell portion (outer shell portion) having a mesoporous structure.
(E) A step of adjusting the hydrophilicity of the particle surface by heating.

(Step (a))
The dispersion is prepared by dispersing the silica core particles in a basic aqueous solution. The silica core particles may have no pores and are preferably in a spherical shape. The silica core particles may be commercially available products or may be synthesized. In the case of synthesis, a generally known method such as a method for synthesizing spherical silica by a sol-gel method using metallic silicon alkoxide as a raw material may be used. The basic aqueous solution is not particularly limited, but from the viewpoint of solubility of the particle surface, aqueous ammonia or an aqueous solution of sodium hydroxide is preferable. In this step (a), for example, the dispersion is stirred for several hours while heating to 60 ° C. or higher to dissolve the surface of the silica core particles.

The concentration of silica core particles per dispersion 1L is the surface area in terms of the silica core particles, preferably 20 to 500 m ² / L is, 30~300m ² / L is more preferable. By setting the concentration of silica core particles (in terms of surface area) to 20 m ² / L or more, when the silica raw materials are reacted under the conditions of pH 8 to 13 in step (c), almost all of the silica raw materials form a shell. Since it is consumed, the formation of new porous silica particles is suppressed. That is, if the concentration of silica core particles (in terms of surface area) is too low, fine porous silica particles may be generated. By setting the concentration (surface area conversion) of the silica core particles to 500 m ² / L or less, a shell portion (outer shell portion) having a mesoporous structure can be formed on the surface of the silica core particles. For example, if the specific surface area used silica core particles of 3.5 m ² / g, a concentration of silica core particles (surface area conversion) to a 20 to 500 m ² / L, the mass concentration of the silica core particles is 20/3. It may be from 5 = 5.71 g / L to 500 / 3.5 = 142.9 g / L.

Alcohol may be added for the purpose of increasing the dispersibility of the silica core particles and the solubility of the particle surface. The alcohol is at least one selected from the group consisting of methanol, ethanol, isopropanol, n-propanol, ethylene glycol and glycerin, and from the viewpoint of further improving the solubility of the silica surface, methanol and / or Ethanol is preferred. The concentration of alcohol is preferably 90% by mass or less, more preferably 85% by mass or less, out of a total of 100% by mass of the alcohol and the basic aqueous solution.

(Step (b))
In the step (b), the surfactant, water and alcohol are added to the dispersion obtained in the step (a) and mixed.

The surfactant acts as a template for forming a mesoporous structure in the shell portion (outer shell portion). The type and concentration of the surfactant tend to have a great influence on the shape of the pores in the shell portion (outer shell portion). The surfactant is not particularly limited, and examples thereof include a surfactant that acts as a template for forming pores in the shell portion (outer shell portion). These surfactants may be used alone or in combination of two or more, but in order to form a shell portion (outer shell portion) having uniform pores, one type of surfactant is used. It is preferable to use an activator. Among the surfactants, alkylammonium halides and alkylamines are preferable. Examples of the alkylammonium halide include tetradecyltrimethylammonium halide, hexadecyltrimethylammonium halide, octadecyltrimethylammonium halide, eicosyltrimethylammonium halide, and docosyltrimethylammonium halide. Examples of the alkylamine include linear alkylamines having 8 to 20 carbon atoms, and dodecylamine is preferable from the viewpoint of further easily forming uniform pores.

When alkylammonium halide or alkylamine is used as the surfactant, the concentration of the surfactant per 1 L of the dispersion is preferably 0.001 to 0.2 mol / L, more preferably 0.01 to 0.1 mol / L. .. By setting the concentration of the surfactant to 0.001 mol / L or more, the effect as a template tends to be more sufficiently exhibited. By setting the concentration of the surfactant to 0.2 mol / L or less, uniform pores tend to be formed more easily.

The concentration of alcohol is preferably 20 to 90% by mass, more preferably 30 to 85% by mass, out of a total of 100% by mass of alcohol and water. When alkoxysilane is used as a silica raw material for forming a shell portion (outer shell portion) having a mesoporous structure, hydrolysis of alkoxysilane is suitable in step (c) by setting the alcohol concentration to 20% by mass or more. The speed can be controlled, and there is a tendency that an outer shell portion having a mesoporous structure can be formed more uniformly on the surface of the silica core particles. On the other hand, if the alcohol concentration exceeds 90% by mass, the hydrolysis rate of alkoxysilane tends to be slow, and it may be difficult to form a shell portion (outer shell portion) having an efficient mesoporous structure.

(Step (c))
In the step (c), the silica raw material is added to the mixed dispersion obtained in (b), and the silica raw material is reacted in the dispersion under the conditions of pH 8 to 13, so that the surface of the silica core particles is coated with silica. The shell portion (outer shell portion) is precipitated to have a substantially uniform thickness. At this time, the micelles of the surfactant are incorporated into the silica to form a shell precursor containing the silica and the surfactant.

The silica raw material may be any as long as it can form a silicon oxide by the reaction, and from the viewpoint of reaction efficiency and handling, at least one selected from the group consisting of alkoxysilane, sodium silicate, and a mixture thereof is preferable. , Alkoxysilane is more preferable, and trimethylmethoxysilane, trimethylethoxysilane, tetraethoxysilane, and tetramethoxysilane are further preferable from the viewpoint of versatility.

The concentration of the silica raw material per 1 L of the total reaction liquid containing the dispersion liquid and the silica raw material is preferably 0.001 to 0.5 mol / L, more preferably 0.005 to 0.3 mol / L. By setting the concentration of the silica raw material to 0.001 mol / L or more, the silica core particles tend to be more sufficiently coated with the shell precursor. By setting the concentration of the silica raw material to 0.5 mol / L or less, almost the entire amount of the silica raw material is consumed for the formation of the shell, so that the formation of new porous silica particles tends to be further suppressed.

The reaction of the silica raw material is carried out from the start to the end of the reaction, for example, at pH 8 to 13, and more preferably 9 to 12.5. If the pH is less than 8, the rate of hydrolysis of alkoxysilane may be slowed down. If the pH exceeds 13, the hydrolysis rate may become uncontrollable.

Examples of the method for adjusting the pH of the reaction solution containing the dispersion liquid and the silica raw material to pH 8 to 13 include a method of adding a basic compound; and a method of using, for example, an alkylamine as a surfactant. The reaction temperature of the silica raw material is preferably 10 to 50 ° C., and the reaction time is preferably 1 to 24 hours.

(Step (d))
In step (d), as a method for removing the surfactant from the shell precursor, (i) particles in which the shell precursor is formed on the surface of the silica core particles (hereinafter, “core-shell type mesoporous silica precursor” or simply “) A method of pouring the mesoporous silica precursor into a solvent in which the surfactant dissolves and eluting the surfactant contained in the shell precursor into the solvent, (ii) firing the core-shell mesoporous silica precursor. Examples thereof include a method of burning off the surfactant contained in the shell precursor, and it is preferable to use the methods (i) and (ii) in combination from the viewpoint of completely removing the surfactant. The firing temperature is preferably 400 to 600 ° C., and the firing time is preferably 1 to 10 hours.

(Step (e))
In the step (e), for example, the hydrophilicity of the surface can be controlled by heating at a firing temperature or higher after firing. The heating temperature is preferably 550 to 1000 ° C, more preferably 550 ° C to 800 ° C. The heating time is preferably 2 to 5 hours, more preferably 2 to 3 hours. When heated at a high temperature for a long time, the structure of the silica particles is deformed, so that it needs to be appropriately adjusted depending on the dryer used and the amount of sample.

(Core-shell type mesoporous silica carrying a polymerization catalyst for olefins)
The core-shell mesoporous silica of the present embodiment includes a core-shell mesoporous silica carrying a catalyst for olefins (for example, a known polymerization catalyst such as a metallocene compound). More specifically, the mesoporous silica of the present embodiment may carry the polymerization catalyst described in Patent No. 5942162 as a polymerization catalyst for producing an ethylene polymer, and is used for producing a propylene polymer. As the polymerization catalyst, the polymerization catalyst described in JP-A-2001-278911 may be carried.

Examples of the olefin that can be polymerized by such an olefin polymerization catalyst include linear or branched α-olefins having 2 to 30 carbon atoms, preferably 2 to 20 carbon atoms (for example, ethylene, propylene, 1-butene). , 2-Butene, 1-Pentene, 3-Methyl-1-butene, 1-Hexen, 4-Methyl-1-Pentene, 3-Methyl-1-Pentene, 1-octene, 1-decene, 1-dodecene, 1 -Tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene); cyclic olefins having 3 to 30 carbon atoms, preferably 3 to 20 (eg, cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetra). Cyclododecene, 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a, 5,8,8a-octahydronaphthalene); polar monomers, vinylcyclohexane, diene, and polyene Can be mentioned. Examples of the polar monomer include acrylic acid, methacrylic acid, fumaric acid, maleic anhydride, itaconic acid, itaconic anhydride, bicyclo (2,2,1) -5-heptene-2,3-dicarboxylic acid anhydride and the like. α, β-unsaturated carboxylic acids, and α, β-unsaturated carboxylic acid metal salts such as these sodium salts, potassium salts, lithium salts, zinc salts, magnesium salts, calcium salts; methyl acrylate, ethyl acrylate, N-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, Α, β-unsaturated carboxylic acid esters such as n-butyl methacrylate and isobutyl methacrylate; such as vinyl acetate, vinyl propionate, vinyl caproate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl trifluoroacetate, etc. Vinyl esters; unsaturated glycidyl such as glycidyl acrylate, glycidyl methacrylate, monoglycidyl itaconic acid ester; halogen-containing olefins such as vinyl chloride and chloroprene. As the diene or polyene, a cyclic or chain compound having 4 to 30 carbon atoms, preferably 4 to 20 carbon atoms and having two or more double bonds is used. Specifically, butadiene, isoprene, 4-methyl-1,3-pentadiene, 1,3-pentadiene, 1,4-pentadiene, 1,5-hexadiene, 1,4-hexadiene, 1,3-hexadiene, 1 , 3-Octadiene, 1,4-octadien, 1,5-octadien, 1,6-octadien, 1,7-octadien, etylidene norbornene, vinyl norbornene, dicyclopentadiene; 7-methyl-1,6-octadien, 4- Ethylidene-8-methyl-1,7-norbornene, 5,9-dimethyl-1,4,8-decatorien and the like can be mentioned. Among these, it is particularly effective in the polymerization of ethylene.

[Method for producing olefin polymer]
The method for producing an olefin polymer of the present embodiment uses core-shell mesoporous silica carrying the polymerization catalyst for olefins of the present embodiment. For example, as a method for producing an ethylene polymer which is an olefin polymer, as described in Japanese Patent No. 5942162, a polymerization step using any of a vapor phase polymerization method, a liquid phase polymerization method, or a slurry polymerization method is performed. Thereby, the ethylene polymer of the present embodiment can be obtained. Further, as a method for producing a propylene polymer, for example, the polypropylene polymer of the present embodiment can be obtained by undergoing the polymerization step described in JP-A-2001-278911.

[Stretched molded product]
The olefin polymer molded product (for example, stretched molded product) of the present embodiment can be obtained, for example, by molding the above-mentioned ethylene polymer by a known molding method for ultra-high molecular weight ethylene polymers. In particular, the ethylene polymer molded product of the present embodiment is preferably rolled and stretched (solid phase stretching). Further, the tensile strength of the stretch-molded product obtained by stretching and molding the ethylene polymer of the present embodiment is preferably 3.0 GPa or more, more preferably 3.5 GPa or more, further preferably 4.0 GPa. As the conditions for solid phase stretch molding, known conditions described in International Publication No. WO 2008/013144, Japanese Patent Application Laid-Open No. 2014-504311 and the like may be used except for using the above-mentioned ethylene polymer. More specifically, a compression step of compressing the ethylene polymer, a rolling step of rolling the ethylene polymer compressed in this compression step, a stretching step of stretching the ethylene polymer rolled in this rolling step, and the like. It is preferable to include a winding step of winding the ethylene polymer stretched in the stretching step. The temperature during this molding is preferably equal to or lower than the melting point of the ethylene polymer particles, and under conditions where the temperature is not raised above the melting point of the ethylene polymer at any time during processing in the compression step and the stretching step. It is more preferable to carry out the compression step and the stretching step, but molding at a melting point or higher may be performed as long as the melting flow does not substantially occur. As a method for measuring and evaluating the stretchability of a stretched molded product using an ethylene polymer and the physical properties of a stretched molded product, the methods described in Examples described later can be used.

[Use of stretched products]
The fibers obtained in this embodiment are various sports clothing, bulletproof, protective clothing, protective gloves, high-performance textiles such as various safety products, various rope products such as tag ropes, mooring ropes, yacht ropes, and construction ropes, fishing threads, and so on. Various braided rope products such as blind cables, net products such as fishing nets and ball-proof nets, reinforcing materials such as chemical filters and battery separators, various non-woven fabrics, curtain materials such as tents, and sports and speakers such as helmets and ski boards. It can be widely applied industrially, such as reinforcing fibers for cones, prepregs, and composites such as concrete reinforcements.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not construed as being limited to these Examples. Therefore, those skilled in the art can carry out the present invention by making various modifications to the examples shown below. The pore physical properties (specific surface area and average pore diameter) of the silica core particles and the core-shell mesoporous silica were measured by a nitrogen gas adsorption method using a pore physical property measuring device (manufactured by Kantachrome, Autosorb).

[Example 1]
As silica core particles, SS-10 (average primary particle diameter 1.0 μm, specific surface area 3.5 m ² / g) manufactured by Tokuyama Corporation was prepared. To a 100 mL flask with a lid, 4.81 g of silica core particles, 6.8 ml of aqueous ammonia, 22 ml of distilled water, and 10 ml of ethanol were added, immersed in an oil bath heated to 90 ° C., and stirred for 3 hours to obtain a dispersion. (The step (a)). Next, 0.73 g of dodecylamine and 28.8 g of distilled water were added as a surfactant, ethanol was added so that the total volume of the dispersion was 80 ml, and these were sufficiently mixed to prepare a mixed dispersion. Prepared (step (b) above). The concentration of silica core particles (in terms of surface area) per 1 L of the dispersion liquid is 210 m ² / L, and the concentration of alcohol is 63% by mass out of the total 100% by mass of alcohol and water, which is per 1 L of the dispersion liquid. The concentration of the surfactant was 0.05 mol / L.

Then, while stirring the mixed dispersion under the condition of 25 ° C., 0.17 g of tetraethoxysilane as a silica raw material was added to the mixed dispersion. The pH of the reaction solution immediately after the addition of tetraethoxysilane was 9.8. The reaction solution was continuously stirred for 20 hours to hydrolyze tetraethoxysilane to form a shell precursor on the surface of the silica core particles (step (c) above). The concentration of tetraethoxysilane per 1 L of the reaction solution was 0.16 mol / L. The pH of the reaction solution after stirring for 20 hours was 9.3.

Then, the reaction solution was filtered using a membrane filter having a pore size of 0.1 μm, and the core-shell mesoporous silica precursor was recovered. The core-shell mesoporous silica precursor was dispersed in 50 mL of ethanol and stirred at 70 ° C. for 1 hour to dissolve and remove a part of dodecylamine. The dispersion was filtered using a membrane filter having a pore size of 0.1 μm, and a core-shell mesoporous silica precursor was recovered. The core-shell mesoporous silica precursor was calcined at 550 ° C. for 3 hours to completely remove dodecylamine (step (d) above). Then, it was heated in an electric furnace at 800 ° C. for 3 hours to obtain a core-shell type mesoporous silica for a polymerization catalyst carrier (step (e)).

(Catalyst support)
1.2 g of the obtained core-shell mesoporous silica was placed in a 100 mL two-necked eggplant flask and vacuum dried at 30 ° C. for 4 hours. While maintaining the vacuum state, 50 mL of a dichloromethane solution of biscyclopentadienyl titanium dichloride (2.0 mmol, major axis 0.63 nm) was added through a septum using a syringe and stirred. After 1 minute, the flask was pressurized with nitrogen to create a nitrogen atmosphere in the flask. Then, 50 mL of a dichloromethane solution of triethylamine (40 mmol) was added, and the mixture was stirred for 4 hours.

After the stirring was stopped and the mixture was allowed to stand, the supernatant was removed, and 50 mL of dichloromethane was added to perform decantation for washing four times. The remaining solids were filtered under air and the filtration residue was washed 3 times with 20 ml methylene chloride. The time required for filtration and cleaning was 30 minutes. The obtained solid material was dried under reduced pressure to obtain a pale yellow titanium-containing core-shell mesoporous silica. This compound was pressure-decomposed using a microwave cracker (model ETHOS TC, manufactured by Milestone General Co., Ltd.), and ICP-AES (inductively coupled plasma mass spectrometer, model X series X7,) was used by the internal standard method. The titanium element concentration was measured by thermofisher scientific (manufactured by Thermo Fisher Scientific Co., Ltd.) analysis. As a result, ^{it was confirmed that 1.4 × 10-2} mmol of titanium atoms were supported per 1 g.

(polymerization)
0.05 g of titanium-containing core-shell mesoporous silica prepared as described above was introduced into a nitrogen-substituted 50 mL Schlenk tube under a nitrogen atmosphere. Then, under a nitrogen atmosphere, 10 ml of hexane and 10.4 mmol of modified methylaluminan (Al atom equivalent concentration 5.7 mass% / hexane) were added in terms of Al atom, and the mixture was stirred at 30 ° C. for 0.5 hour to activate. It was prepared as a chemical catalyst slurry. Then, the activation catalyst slurry was irradiated with ultrasonic waves at 100 kHz for 5 minutes.

800 mL of hexane was added to a fully nitrogen-substituted 1.5 L autoclave, 1.0 mL of the modified methylarmoxane was added as a scavenger, and the mixture was stirred for 5 minutes. The activation catalyst slurry was then introduced into the autoclave with a syringe. Next, ethylene was used to ^{pressurize the system to 8.3 kg / cm 2} , and while continuously supplying ethylene, the mixture was stirred for 2 hours at a rotation speed of 30 rpm while maintaining the autoclave temperature at 30 ° C. After completion of the polymerization reaction, the unreacted gas was purged. The contents of the autoclave were put into 1000 ml of acidic methanol containing 5% by mass of hydrochloric acid, the precipitated polymer was filtered off and dried under reduced pressure at 30 ° C. for about 6 hours to obtain 55 g of a powdery ethylene polymer. The polymer yield was divided by the amount of Ti in the catalyst and the polymerization time to calculate the catalytic activity. The obtained ethylene polymer was evaluated for (1) viscosity average molecular weight Mv, (2) heat of fusion ΔH by differential scanning calorimetry (DSC), and (3) stretchability according to the method described below. ..

(1) Viscosity average molecular weight (Mv)
It was determined by the method shown below according to ISO1628-3 (2010). First, 20 mg of ethylene polymer finely crushed in an agate mortar was weighed in a melting tube, the melting tube was replaced with nitrogen, and then 20 mL of decahydronaphthalene (2,6-di-t-butyl-4-methylphenol) was added at 1 g / g. L was added), and the mixture was stirred at 150 ° C. for 2 hours to dissolve the ethylene polymer. The fall time (ts) between the marked lines was measured using a Canon-Fenceke type viscometer (manufactured by Shibata Scientific Technology Co., Ltd .: product number -100) in a constant temperature bath at 135 ° C.

Similarly, the amount of ethylene polymer was measured 10 mg, 5 mg, fall time between the marked lines even for samples changed to 2mg of (t _{s). As a blank, the fall time (t b} ) of only decahydronaphthalene (including 2,6-di-t-butyl-4-methylphenol) containing no ethylene polymer was measured. _{The reduced viscosity (η sp} / C) of the ethylene polymer obtained according to the following formula A is plotted, and the concentration (C) (unit: g / dL) and the reduced viscosity (η _sp / C) of the ethylene polymer are calculated. A linear equation was derived, and the extreme viscosity ([η], unit: dL / g) extrapolated to a concentration of 0 was determined.
_{η sp / C = (t s} / t b -1) /0.1 ··· ( formula A)

Next, using the following mathematical formula B, the viscosity average molecular weight (Mv) was calculated using the value of the ultimate viscosity [η].
Mv = (5.34 × 10 ⁴ ) × [η] 1.49 ・ ・ ・ (Formula B)

(2) Heat of fusion ΔH by differential scanning calorimetry (DSC)
Measurements were made using a Perkin Elmer Pyris1 DSC as a differential scanning calorimetry (DSC). A measurement sample given a heat history of 110 ° C. for 6 hours under a reduced pressure environment of 0.1 to 0.5 kPa was weighed at 8.3 to 8.5 mg with an electronic balance and placed in an aluminum sample pan. An aluminum cover was attached to this pan and installed in the differential scanning calorimeter. The sample and the reference sample were held at 50 ° C. for 1 minute while purging nitrogen at a flow rate of 20 mL / min, then heated from 50 ° C. to 180 ° C. at a heating rate of 10 ° C./min, and held at 180 ° C. for 5 minutes. Then, it was cooled to 50 ° C. at a cooling rate of 10 ° C./min. The baseline of the temperature rising DSC curve obtained at that time was corrected, the peak area was calculated by the analysis software Pyris software (version 7), and the peak area was divided by the sample mass to derive the heat of fusion ΔH.
The heat of fusion ΔH is an index of the crystallinity of the polymer, and the larger the heat of fusion ΔH, the higher the crystallinity, that is, the higher the crystallinity.

(3) Stretchability A 3 gram ethylene polymer was pressed by a press molding machine at a maximum temperature of 126 ° C. and an average pressure of 11 MPa for 10 minutes. Cooling was carried out at 25 ° C. for 10 minutes while maintaining 11 MPa. The obtained press sheet was preheated at 140 ° C. for 3 minutes and rolled at 130 ° C. with a roll rolling mill having a roll feeding speed of 1 m / min so as to have a draw ratio of 6 times. The sheet obtained by the rolling process is cut out, set in a tensile tester (Instron Corporation, INSTRON (registered trademark) 5564) so that the chuck distance is 15 mm, and roll-rolled at 130 ° C. and a drawing speed of 30 mm / min. It was uniaxially stretched in the same direction. The stretching test was carried out 5 times, and the measured average value of the tensile stress at the time of stretching from the press sheet to 30 times was evaluated as the draw workability according to the following criteria.
A: The tensile stress was less than 20 MPa.
B: The tensile stress was 20 MPa or more and less than 30 MPa.
C: The tensile stress was 30 MPa or more.

[Comparative Example 1]
An ethylene polymer was obtained by the same operation as in Example 1 except that the mesoporous silica MCM41 sold by Sigma-Aldrich Japan GK was used instead of the core-shell type mesoporous silica.

[Comparative Example 2]
An ethylene polymer was obtained by the same operation as in Example 1 except that the non-porous silica SS-10 manufactured by Tokuyama Corporation was used instead of the core-shell mesoporous silica.

[Comparative Example 3]
No carrier was used, except that 5 mL of a toluene solution of 0.0075 g of biscyclopentadienyl titanium dichloride and 1.8 mL of the modified methylarmoxane were mixed to prepare an activation catalyst solution and introduced into an autoclave. An ethylene polymer was obtained by the same operation as in Example 1.

The core-shell type mesoporous silica for a polymerization catalyst carrier of the present embodiment is useful as a polymerization catalyst carrier because a homogeneous polymer having a high molecular weight and a high degree of crystallinity (for example, a powdery polymer) can be obtained and catalyst loss can be reduced. Is.

Claims (6)

A core-shell type having a core part and a shell part,
Wherein the core portion is a non-pore, wherein the shell portion has a mesoporous structure arrayed pores radially from the surface of the core portion to the surface of the shell portion, co Asher type that responsible lifting the olefin polymerization catalyst for Mesoporous silica. The average primary particle diameter of 0.1 to 10 [mu] m, according to claim 1 co Asher type mesoporous silica. The thickness of the shell portion is 500nm or less, according to claim 1 or 2 co Asher type mesoporous silica. Or less proportion of 40% of the hydrophilic surface area to the entire specific surface area, according to any one of claims 1 to 3 U Asher type mesoporous silica. The core-shell mesoporous silica according to any one of claims 1 to 4, wherein the polymerization catalyst for olefin contains a metallocene compound. A method for producing an olefin polymer using a core-shell mesoporous silica carrying the polymerization catalyst for an olefin according to any one of claims 1 to 5.

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