Method for producing propylene-based block copolymer

Abstract

The present invention provides a method for easily producing a propylene-based block copolymer that has a high melt flow rate and a high content ratio of a propylene / α-olefin copolymer component, the method having excellent polymerization activity in a first polymerization step and a second polymerization step. This method for producing a propylene-based block copolymer includes: a first polymerization step for obtaining a propylene-based polymer by polymerizing olefins that include 95-100 mass% of propylene under the temperature condition of 45°C to 65°C with use of an olefin polymerization catalyst comprising (A) a solid catalyst component for olefin polymerization which contains titanium, magnesium, a halogen and a 1,3-diether compound and (B) an organoaluminum compound; and subsequently, a second polymerization step for obtaining a propylene / α-olefin copolymer by copolymerizing olefins that include not less than 5 mass% but less than 95 mass% of propylene and an α-olefin excluding propylene in the presence of the propylene-based polymer under the temperature condition of 50°C to 90°C.

Description

Method for producing propylene-based block copolymer

[0001] The present invention relates to a method for producing a propylene-based block copolymer.

[0002] Conventionally, olefins such as propylene have been polymerized using an olefin polymerization catalyst. In particular, propylene-based block copolymers polymerized using an olefin polymerization catalyst have become preferred for use due to their excellent balance between rigidity and impact resistance.

[0003] Among propylene-based block copolymers, ethylene-propylene block copolymers in particular have good mechanical properties such as rigidity and heat resistance, and can be produced relatively inexpensively, and therefore are used in a wide range of applications.

[0004] The ethylene-propylene block copolymer is a blend of a propylene-based polymer mainly composed of propylene and a random copolymer of propylene and ethylene, and is generally produced by a method in which each polymer is sequentially polymerized under conditions corresponding to the polymer to be obtained and blended in a reaction vessel.

[0005] For example, a suitable polymerization reaction for obtaining an ethylene-propylene block copolymer is to carry out a homopolymerization reaction of propylene or a random copolymerization reaction of propylene with a small amount of ethylene in a first step, and then carry out a copolymerization reaction of propylene and ethylene in a second step in the presence of the obtained propylene-based polymer. The ethylene-propylene block copolymer obtained by the above method is melted and then molded using various molding machines, stretching machines, etc., and used for various applications such as molded products such as automobile parts and home appliance parts, as well as containers and sheets.

[0006] As a catalyst for olefin polymerization used in producing the above-mentioned propylene-based block copolymer, many catalysts for olefin polymerization have been proposed, which contain a solid catalyst component containing, as essential components, a magnesium atom, a titanium atom, a halogen atom, and an internal electron donor compound such as a phthalate ester, an organoaluminum compound, and an organosilicon compound as an external electron donor compound (see, for example, Patent Document 1).

[0007] Japanese Patent Application Laid-Open No. 2003-268060

[0008] The ethylene-propylene block copolymer is widely used in injection molding of automobile bumpers and the like, and therefore, in order to improve the productivity of the injection molding process, it is desirable that the copolymer have an excellent melt flow rate (hereinafter also referred to as MFR).

[0009] Furthermore, in order to improve the impact resistance of the ethylene-propylene block copolymer, it is necessary to set the content ratio of the random copolymer component to a certain value or more. Furthermore, it is also required that the majority of the ethylene constituting the ethylene-propylene block copolymer is incorporated into the random copolymer, and that the amount of crystalline polyethylene is small. Therefore, there is a demand for a technology that has high polymerization activity during the formation of the random copolymer of propylene and ethylene, which is the rubber portion, and that allows ethylene to be efficiently introduced into the random copolymer.

[0010] As described above, there is known a method for producing an ethylene-propylene block copolymer, in which a propylene polymer component mainly consisting of propylene is produced in a first polymerization step, and propylene and ethylene are randomly copolymerized in the presence of the propylene polymer in a second polymerization step. In the above polymerization reaction, if the polymerization activity in the first polymerization step becomes too high, it becomes difficult to extend the polymerization activity in the second polymerization step, and as a result, the content of the propylene / ethylene random copolymer component in the resulting propylene block copolymer is likely to decrease.

[0011] In order to solve the above technical problems, the present inventors came up with the idea of ​​suppressing the polymerization temperature in the first polymerization step to a temperature lower than the normal polymerization temperature, thereby suppressing the polymerization activity in the first polymerization step, and thereby increasing the polymerization activity in the second polymerization step.

[0012] However, the present inventors have conducted studies and found that when an olefin polymerization catalyst containing a phthalate ester as an internal electron donor compound as described in Patent Document 1 is used and the polymerization temperature in the first polymerization step is controlled to a temperature lower than a normal polymerization temperature, the yield of the resulting ethylene-propylene block copolymer is also reduced.

[0013] Furthermore, when a catalyst for olefin polymerization containing a phthalate ester as an internal electron donor compound as described in Patent Document 1 is used for the polymerization of olefins, it is difficult to obtain an ethylene-propylene block copolymer having an excellent melt flow rate (MFR).

[0014] In addition, when an attempt is made to obtain an ethylene-propylene block copolymer having a high content ratio of propylene / ethylene random copolymer by improving the polymerization activity in the second polymerization step, the fluidity of the obtained ethylene-propylene block copolymer usually decreases as the content ratio of propylene / ethylene random copolymer increases, making it difficult to obtain an ethylene-propylene block copolymer having a sufficient melt flow rate (MFR).

[0015] Under these circumstances, an object of the present invention is to provide a method for easily producing a propylene-based block copolymer, which has excellent polymerization activity in a first polymerization step in which a homopolymerization reaction of propylene or a copolymerization reaction of propylene with a small amount of an α-olefin (excluding propylene) is carried out, and also has excellent polymerization activity in a second polymerization step in which a copolymerization reaction of propylene and an α-olefin (excluding propylene) is carried out in the presence of the propylene-based polymer obtained in the first polymerization step, and which has a melt flow rate that is sufficiently high for practical use and a high content of propylene / α-olefin copolymer.

[0016] The present inventors have conducted extensive studies to solve the above technical problems, and have found that the above problems can be solved by carrying out a first polymerization step in which olefins containing 95 to 100% by mass of propylene are polymerized at a temperature of 45 to 65°C using a catalyst for olefin polymerization comprising (A) a solid catalyst component for olefin polymerization containing titanium, magnesium, a halogen, and a 1,3-diether compound that is an internal electron-donor compound, and (B) an organoaluminum compound, to obtain a propylene polymer, and then carrying out a second polymerization step in which olefins containing 5 to 95% by mass of propylene and an α-olefin other than propylene are copolymerized at a temperature of 50 to 90°C in the presence of the propylene polymer to obtain a propylene / α-olefin copolymer, thereby completing the present invention.

[0017] That is, the present invention provides: (1) a method for producing a propylene-based block copolymer, comprising: using a catalyst for polymerizing olefins comprising (A) a solid catalyst component for polymerizing olefins containing titanium, magnesium, a halogen, and a 1,3-diether compound as an internal electron donor compound; and (B) an organoaluminum compound; and carrying out a first polymerization step of polymerizing olefins containing 95 to 100% by mass of propylene at a temperature of 45 to 65°C to obtain a propylene-based polymer; and then carrying out a second polymerization step of copolymerizing olefins containing 5 to 95% by mass of propylene and an α-olefin other than propylene in the presence of the propylene-based polymer at a temperature of 50 to 90°C to obtain a propylene / α-olefin copolymer; (2) a method for producing a propylene-based block copolymer, wherein the (B) organoaluminum compound is a compound represented by the following general formula (I): R １ ｐ AlQ ３－ｐ (I) (wherein, R １ is an alkyl group having 1 to 6 carbon atoms, Q is a hydrogen atom or a halogen atom, p is 0<p≦3, and R １ If there are multiple R １may be the same or different, and when a plurality of Q's are present, each Q may be the same or different.), (3) A method for producing a propylene-based block copolymer according to (1) above, wherein the catalyst for polymerizing olefins further contains (C) an external electron donor compound, and (4) A method for producing a propylene-based block copolymer according to any one of (1) to (3) above, wherein the resulting propylene-based block copolymer has a propylene / α-olefin moiety content of 25.0 to 50.0 mass%.

[0018] According to the present invention, there can be provided a method for easily producing a propylene-based block copolymer which exhibits excellent polymerization activity in a first polymerization step in which a homopolymerization reaction of propylene or a copolymerization reaction of propylene with a small amount of an α-olefin (excluding propylene) is carried out, and also exhibits excellent polymerization activity in a second polymerization step in which a copolymerization reaction of propylene and an α-olefin (excluding propylene) is carried out in the presence of the propylene-based polymer obtained in the first polymerization step, and which has a melt flow rate that is sufficiently high for practical use and a high content of a propylene / α-olefin copolymer component.

[0019] First, a method for producing a propylene-based block copolymer according to the present invention will be described. The method for producing a propylene-based block copolymer according to the present invention is characterized by carrying out a first polymerization step in which olefins containing 95 to 100% by mass of propylene are polymerized at a temperature of 45 to 65°C using an olefin polymerization catalyst containing (A) a solid catalyst component for olefin polymerization containing titanium, magnesium, a halogen, and a 1,3-diether compound as an internal electron donor compound, and (B) an organoaluminum compound, to obtain a propylene polymer, and then carrying out a second polymerization step in which olefins containing 5 to 95% by mass of propylene and an α-olefin other than propylene are copolymerized in the presence of the propylene polymer at a temperature of 50 to 90°C to obtain a propylene / α-olefin copolymer.

[0020] In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component (A) for olefin polymerization containing titanium, magnesium, a halogen, and a 1,3-diether compound as an internal electron donor compound can be a contact reaction product obtained by contacting raw material components serving as sources of magnesium, titanium, and halogen with an internal electron donor compound containing a 1,3-diether compound in an organic solvent to cause a reaction. Specific examples of the solid catalyst component (A) for olefin polymerization can include a contact reaction product obtained by using a magnesium compound and a tetravalent titanium halogen compound as raw material components serving as sources of magnesium, titanium, and halogen, and contacting these raw material components with an internal electron donor compound containing a 1,3-diether compound.

[0021] The magnesium compound can be one or more selected from dialkoxymagnesium, magnesium dihalide, alkoxymagnesium halide, etc. Among the magnesium compounds, dialkoxymagnesium or magnesium dihalide is preferred, and specific examples include dimethoxymagnesium, diethoxymagnesium, dipropoxymagnesium, dibutoxymagnesium, ethoxymethoxymagnesium, ethoxypropoxymagnesium, butoxyethoxymagnesium, magnesium dichloride, magnesium dibromide, magnesium diiodide, etc., with diethoxymagnesium and magnesium dichloride being particularly preferred.

[0022] Of the above magnesium compounds, dialkoxymagnesium may be obtained by reacting metallic magnesium with an alcohol in the presence of a halogen or a halogen-containing metal compound.

[0023] The dialkoxymagnesium is preferably in the form of granules or powder, and the shape thereof may be irregular or spherical.

[0024] When a spherical dialkoxymagnesium is used, a polymer powder having a better particle shape (more spherical) and a narrow particle size distribution can be obtained, the handling operability of the polymer powder produced during the polymerization operation can be improved, and the occurrence of blockages and the like due to fine particles contained in the produced polymer powder can be suppressed.

[0025] The spherical dialkoxymagnesium does not necessarily have to be perfectly spherical, and ellipsoidal or potato-shaped ones can also be used.

[0026] The average particle size (average particle size D50) of the dialkoxymagnesium is preferably 1.0 to 200.0 μm, and more preferably 5.0 to 150.0 μm. Here, the average particle size D50 refers to the particle size at 50% of the cumulative particle size in the volume cumulative particle size distribution when measured using a laser light scattering diffraction particle size analyzer. When the dialkoxymagnesium is spherical, the average particle size D50 is preferably 1.0 to 100.0 μm, more preferably 5.0 to 80.0 μm, and even more preferably 10.0 to 70.0 μm.

[0027] Furthermore, the particle size distribution of the dialkoxy magnesium is preferably narrow, with few fine and coarse particles. Specifically, when measured using a laser light scattering diffraction particle size analyzer, the dialkoxy magnesium preferably contains 20% or less, more preferably 10% or less, of particles with a particle diameter of 5.0 μm or less. On the other hand, when measured using a laser light scattering diffraction particle size analyzer, the particle diameter of 100.0 μm or more is preferably 20% or less, more preferably 10% or less. Furthermore, when the particle size distribution is expressed as ln(D90 / D10), it is preferably 3 or less, more preferably 2 or less. Here, D90 means the particle size at 90% of the cumulative particle size in the volume cumulative particle size distribution when measured using a laser light scattering diffraction particle size analyzer. Furthermore, D10 means the particle size at 10% of the cumulative particle size in the volume cumulative particle size distribution when measured using a laser light scattering diffraction particle size analyzer.

[0028] The method for producing the spherical dialkoxymagnesium is exemplified in, for example, Japanese Patent Application Laid-Open Nos. 62-51633, 3-74341, 4-368391, and 8-73388.

[0029] The magnesium compound is preferably in the form of a solution or suspension during the reaction, and being in the form of a solution or suspension allows the reaction to proceed favorably.

[0030] When the magnesium compound is solid, it can be dissolved in a solvent capable of solubilizing the magnesium compound to form a magnesium compound solution, or can be suspended in a solvent incapable of solubilizing the magnesium compound to form a magnesium compound suspension. When the magnesium compound is liquid, it may be used as a magnesium compound solution as is, or may be further dissolved in a solvent capable of solubilizing the magnesium compound to form a magnesium compound solution.

[0031] Examples of compounds capable of solubilizing solid magnesium compounds include at least one compound selected from the group consisting of alcohols, ethers, and esters, and alcohols such as ethanol, propanol, butanol, and 2-ethylhexanol are preferred, with 2-ethylhexanol being particularly preferred. On the other hand, examples of media that do not have the ability to solubilize solid magnesium compounds include one or more solvents selected from saturated hydrocarbon solvents and unsaturated hydrocarbon solvents that do not dissolve magnesium compounds.

[0032] In the method for producing a propylene-based block copolymer according to the present invention, the tetravalent titanium halide compound, which is a raw material component serving as a source of titanium and halogen constituting the solid catalyst component for olefin polymerization (A), is not particularly limited, but may be a compound represented by the following general formula (II): Ti(OR ２ ) ｔ X ４－ｔ (II) (wherein, R ２represents an alkyl group having 1 to 4 carbon atoms, X represents a halogen atom such as a chlorine atom, a bromine atom or an iodine atom, and t satisfies 0≦s≦3.

[0033] In the above general formula (II), t is 0≦t≦3, and specifically, t may be 0, 1, 2, or 3.

[0034] Examples of titanium halides represented by the general formula (II) include one or more titanium tetrahalides selected from titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, etc. Examples of alkoxytitanium halides represented by the general formula (II) include one or more selected from methoxytitanium trichloride, ethoxytitanium trichloride, propoxytitanium trichloride, n-butoxytitanium trichloride, dimethoxytitanium dichloride, diethoxytitanium dichloride, dipropoxytitanium dichloride, di-n-butoxytitanium dichloride, trimethoxytitanium chloride, triethoxytitanium chloride, tripropoxytitanium chloride, tri-n-butoxytitanium chloride, etc. Examples of tetravalent titanium halide compounds include titanium tetrahalides, and more preferably titanium tetrachloride. These titanium compounds may be used alone or in combination of two or more.

[0035] In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component for olefin polymerization (A) contains a 1,3-diether compound as an internal electron donor compound.

[0036] In the present application, the term "1,3-diether compound" refers to a group of compounds having a structure in which ether groups are bonded to the 1,3-positions of a propane skeleton (1,3-dialkoxypropane structure), and which may further contain desired substituents.

[0037] The 1,3-diether compound may be a compound represented by the following general formula (III): ３ OCH ２ CR ４ R５ CH ２ OR ６ (III) (wherein, R ４ and R ５ represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a vinyl group, an alkenyl group having 3 to 12 carbon atoms, a cycloalkyl group or a cycloalkenyl group having 3 to 12 carbon atoms, an aromatic hydrocarbon group or a halogen-substituted aromatic hydrocarbon group having 6 to 12 carbon atoms, an aromatic hydrocarbon group having 7 to 12 carbon atoms and having a substituent, an alkylamino group having 1 to 12 carbon atoms, or a dialkylamino group having 2 to 12 carbon atoms. ４ and R ５ may be the same or different. ４ and R ５ may be bonded to each other to form a ring. ３ and R ６ represents an alkyl group having 1 to 12 carbon atoms, a vinyl group, an alkenyl group having 3 to 12 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms, a halogen-substituted aromatic hydrocarbon group, or an aromatic hydrocarbon group having 7 to 12 carbon atoms and having a substituent. ３ and R ６ may be the same or different from each other.

[0038] Specific examples of the 1,3-diether compound include one or more selected from 2-isopropyl-2-isobutyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, 2,2-dicyclohexyl-1,3-dimethoxypropane, 2,2-bis(cyclohexylmethyl)1,3-dimethoxypropane, and 9,9-bis(methoxymethyl)fluorene. Of these, one or more selected from 2-isopropyl-2-isobutyl-1,3-dimethoxypropane, 2-isopropyl-2-isopentyl-1,3-dimethoxypropane, and 9,9-bis(methoxymethyl)fluorene are preferred.

[0039] In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component for olefin polymerization (A) contains a 1,3-diether compound as an internal electron donor compound, so that polymerization activity can be easily maintained even when the polymerization reaction is carried out at a lower-than-usual temperature of about 45°C to 65°C in the first polymerization step described below, and high polymerization activity can also be easily exhibited in the second polymerization step. Furthermore, in the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component for olefin polymerization (A) contains a 1,3-diether compound as an internal electron donor compound, so that the resulting propylene-based block copolymer can maintain a high melt flow rate (MFR) even when the content ratio of propylene / α-olefin random copolymer is as high as about 25.0 to 50.0 mass%.

[0040] In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component for olefin polymerization (A) may contain, as an internal electron donor compound, in addition to a 1,3-diether compound, one or more compounds selected from benzoate esters, diesters (malonic acid diesters, maleic acid diesters, succinic acid diesters, glutaric acid esters), diol diesters, carbonate ethers, carbonate diesters, diester ethers, heteroatom-containing compounds, etc. In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component for olefin polymerization (A) may or may not contain a phthalate ester as an internal electron donor compound, but preferably does not contain a phthalate ester.

[0041] In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component (A) for olefin polymerization preferably contains the 1,3-diether compound in an amount of 60 to 100% by weight, more preferably 70 to 100% by weight, and even more preferably 80 to 100% by weight, based on the total content of the internal electron donor compound.

[0042] In the method for producing a propylene-based block copolymer according to the present invention, since the solid catalyst component for polymerizing olefins (A) contains a 1,3-diether compound in the above-mentioned ratio relative to the total content of internal electron donor compounds, the olefin polymerization catalyst containing the solid catalyst component for polymerizing olefins (A) can easily maintain polymerization activity even when a polymerization reaction is carried out in the first polymerization step described below at a lower-than-usual temperature of about 45°C to 65°C, and can also easily exhibit high polymerization activity in the second polymerization step. Furthermore, in the method for producing a propylene-based block copolymer according to the present invention, since the solid catalyst component for polymerizing olefins (A) contains a 1,3-diether compound as an internal electron donor compound in the above-mentioned ratio, the resulting propylene-based block copolymer can easily have a sufficiently high melt flow rate (MFR), even when the content ratio of propylene / α-olefin random copolymer increases to about 25.0 to 50.0 mass%.

[0043] In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component (A) for olefin polymerization may further contain polysiloxane. Polysiloxane is a polymer having a siloxane bond (—Si—O— bond) in the main chain, and is also collectively called silicone oil. It has a viscosity of 0.02 to 100 cm at 25° C. ２ / s (2 to 10,000 centistokes), more preferably 0.03 to 5 cm ２ In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component (A) for polymerizing olefins further contains a polysiloxane, which makes it possible to easily produce an olefin polymer having excellent stereoregularity or crystallinity when the solid catalyst component (A) is subjected to the polymerization of olefins, and further makes it possible to easily reduce the amount of fine powder in the produced olefin polymer.

[0044] In the method for producing a propylene-based block copolymer according to the present invention, the solid catalyst component (A) for olefin polymerization can be prepared, for example, by contacting a dialkoxymagnesium, a tetravalent titanium halide compound, an internal electron donor compound, and, if necessary, a polysiloxane with each other in an inert organic solvent.

[0045] The inert organic solvent is preferably a liquid at room temperature (20°C) and has a boiling point of 50 to 150°C, and more preferably a saturated hydrocarbon compound or an aromatic hydrocarbon compound that is a liquid at room temperature and has a boiling point of 50 to 150°C.

[0046] Specific examples of the inert organic solvent include one or more selected from linear aliphatic hydrocarbon compounds such as hexane, heptane, and decane, branched aliphatic hydrocarbon compounds such as methylheptane, alicyclic hydrocarbon compounds such as cyclohexane, methylcyclohexane, and ethylcyclohexane, and aromatic hydrocarbon compounds such as toluene, xylene, and ethylbenzene. Among the inert organic solvents, aromatic hydrocarbon compounds that are liquid at room temperature and have a boiling point of 50 to 150° C. are preferred because they can easily improve the activity of the resulting solid catalyst component and can easily improve the stereoregularity of the resulting polymer.

[0047] In the process for producing a propylene-based block copolymer according to the present invention, when the components are brought into contact with each other to prepare (A) the solid catalyst component for olefin polymerization, the process can be carried out in an inert gas atmosphere.

[0048] Specifically, the components are contacted with each other while stirring in a vessel equipped with a stirrer under an inert gas atmosphere and under conditions where moisture and the like have been removed, and then reacted at a predetermined temperature to obtain (A) a solid catalyst component for olefin polymerization.

[0049] The temperature at which the components are brought into contact with each other may be in a relatively low range around room temperature when the components are simply brought into contact with each other and stirred and mixed, or when the components are dispersed or suspended and modified.

[0050] When the components are brought into contact with each other and then reacted to obtain a product, the temperature range is preferably 40 to 130°C, and in this case, it is preferable to maintain the components at the same temperature after contacting them to allow the reaction to occur.

[0051] If the temperature at which the product is obtained is less than 40° C., the reaction does not proceed sufficiently, and the resulting solid catalyst component is unlikely to exhibit sufficient performance. If the temperature exceeds 130° C., the solvent used will evaporate significantly, making it difficult to control the reaction.

[0052] The reaction time for obtaining the above product is preferably 1 minute or more, more preferably 10 minutes or more, and even more preferably 30 minutes or more.

[0053] The ratio of the amounts of each component used when preparing (A) the solid catalyst component for olefin polymerization varies depending on the preparation method, and may be determined appropriately.

[0054] When preparing (A) the solid catalyst component for olefin polymerization, the tetravalent titanium halide compound is contacted in an amount of preferably 0.50 to 100.00 mol, more preferably 0.50 to 10.00 mol, and even more preferably 1.00 to 5.00 mol per 1.00 mol of the dialkoxymagnesium compound.

[0055] In addition, when preparing (A) the solid catalyst component for olefin polymerization, the internal electron donor compound is preferably contacted in an amount of 0.01 to 10.00 mol, more preferably 0.01 to 1.00 mol, and even more preferably 0.02 to 0.6 mol, per 1.00 mol of dialkoxymagnesium.

[0056] Furthermore, when a polysiloxane is used in preparing (A) the solid catalyst component for olefin polymerization, the amount of polysiloxane contacted is preferably 0.01 to 100.00 g, more preferably 0.05 to 80.00 g, and even more preferably 1.00 to 50.00 g, per 1.00 mol of dialkoxymagnesium.

[0057] In addition, when preparing (A) the solid catalyst component for olefin polymerization, the amount of the inert organic solvent used is preferably 0.001 to 500,000 mol, more preferably 0.001 to 70,000 mol, and even more preferably 0.005 to 50,000 mol per 1.000 mol of dialkoxymagnesium.

[0058] As a particularly preferred method for preparing the solid catalyst component for olefin polymerization, the following preparation method can be mentioned.

[0059] First, a dialkoxymagnesium is suspended in an inert organic solvent containing an alicyclic hydrocarbon compound having a boiling point of 50 to 150°C to obtain a suspension. Next, a reaction treatment is carried out by contacting the obtained suspension with a tetravalent titanium halide compound. Before or after contacting the suspension with the tetravalent titanium halide compound, an internal electron donor compound is contacted at -20 to 130°C. If necessary, a reaction treatment is further carried out by contacting with a polysiloxane. In the above preparation method, it is desirable to carry out an aging reaction at a low temperature before or after contacting with the internal electron donor compound.

[0060] The (A) solid catalyst component for olefin polymerization preferably contains titanium atoms in an amount of 1.0 mass % to 10.0 mass %, more preferably 1.5 mass % to 8.0 mass %, and even more preferably 1.5 mass % to 5.0 mass %.

[0061] The (A) solid catalyst component for olefin polymerization preferably contains magnesium atoms in an amount of 10.0 to 70.0 mass%, more preferably 10.0 to 50.0 mass%, even more preferably 15.0 to 40.0 mass%, and still more preferably 15.0 to 25.0 mass%.

[0062] The (A) solid catalyst component for olefin polymerization preferably contains halogen atoms in an amount of 20.0 mass% to 90.0 mass%, more preferably 30.0 mass% to 85.0 mass%, even more preferably 40.0 mass% to 80.0 mass%, and still more preferably 45.0 mass% to 80.0 mass%.

[0063] The (A) solid catalyst component for olefin polymerization preferably contains the internal electron donor compound in a total amount of 0.5% by mass to 30.0% by mass, more preferably 1.0% by mass to 25.0% by mass, and even more preferably 2.0% by mass to 20.0% by mass.

[0064] In the present application, the content of titanium atoms contained in the solid catalyst component for olefin polymerization means a value measured in accordance with the method (oxidation-reduction titration) described in JIS 8311-1997 "Method for determining titanium in titanium ore."

[0065] In the present application, the magnesium content in the solid catalyst component for olefin polymerization means a value measured by an EDTA titration method in which the solid catalyst component for olefin polymerization is dissolved in a hydrochloric acid solution and titrated with an EDTA solution.

[0066] In the present application, the content of halogen atoms contained in a solid catalyst component for olefin polymerization means a value measured by silver nitrate titration in which the solid catalyst component is treated with a mixed solution of sulfuric acid and pure water to prepare an aqueous solution, a predetermined amount of which is then taken and titrated for halogen atoms with a standard silver nitrate solution.

[0067] In addition, in the present application documents, the content ratio of the internal electron donor compound means a value obtained by hydrolyzing a solid catalyst, extracting the internal electron donor with an aromatic solvent, and measuring the content of the solution by gas chromatography FID (Flame Ionization Detector) method.

[0068] In the method for producing a propylene-based block copolymer according to the present invention, the catalyst for olefin polymerization contains (B) an organoaluminum compound.

[0069] In the method for producing a propylene-based block copolymer according to the present invention, the organoaluminum compound (B) constituting the catalyst for olefin polymerization is preferably a compound represented by the following general formula (I): １ ｐ AlQ ３－ｐ (I) (wherein, R １is an alkyl group having 1 to 6 carbon atoms, Q is a hydrogen atom or a halogen atom, p is 0<p≦3, and R １ If there are multiple R １ may be the same or different, and when there are a plurality of Qs, each Q may be the same or different.

[0070] In the organoaluminum compound represented by general formula (I), R １ is an alkyl group having 1 to 6 carbon atoms, and specific examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group.

[0071] In the organoaluminum compound represented by the above general formula (I), Q represents a hydrogen atom or a halogen atom. When Q is a halogen atom, examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0072] In the organoaluminum compound represented by the general formula (I), p satisfies 0<p≦3, is preferably 2 to 3, and more preferably 2, 2.5 or 3.

[0073] Specific examples of the organoaluminum compound represented by the general formula (I) include one or more compounds selected from the group consisting of triethylaluminum, diethylaluminum chloride, triisobutylaluminum, diethylaluminum bromide, and diethylaluminum hydride, with triethylaluminum and triisobutylaluminum being preferred.

[0074] In the method for producing a propylene-based block copolymer according to the present invention, the catalyst for olefin polymerization contains the specific organoaluminum compound represented by the general formula (I) above, which is believed to improve the action of the organoaluminum compound on the internal electron donor compound constituting the solid catalyst component for olefin polymerization, thereby optimally activating the solid catalyst component for olefin polymerization. As a result, it is believed that the solid catalyst component exhibits excellent catalytic activity during polymerization treatment, and an olefin polymer having excellent stereoregularity can be produced.

[0075] In the method for producing a propylene-based block copolymer according to the present invention, the catalyst for olefin polymerization preferably contains (A) the solid catalyst component for olefin polymerization and (B) the organoaluminum compound, as well as (C) an external electron donor compound.

[0076] In the method for producing the propylene-based block copolymer according to the present invention, the external electron donor compound (C) may be, for example, a compound represented by the following general formula (IV): ７ ｒ Si(NR ８ R ９ ) ｓ (OR １０ ) ４－（ｒ＋ｓ） (IV) (wherein r is 0 or 1 to 2, s is 0 or 1 to 2, r+s is 0 or 1 to 4, R ７ , R ８ or R ９ R is a hydrogen atom or a group selected from a linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted cycloalkyl group, a phenyl group, an allyl group, and an aralkyl group, which may contain a heteroatom and may be the same or different from each other. ８ and R ９ may be bonded to form a ring, and R ７ , R ８ and R ９ may be the same or different. １０ is any group selected from an alkyl group, a cycloalkyl group, a phenyl group, a vinyl group, an allyl group, and an aralkyl group having 1 to 4 carbon atoms, and may contain a heteroatom.

[0077] In the silicon compound represented by the general formula (IV), R ７ R is a group selected from a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted cycloalkyl group, a phenyl group, an allyl group, and an aralkyl group, and may contain a heteroatom. ７As the alkyl group, a linear or branched alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms is preferred, and a linear or branched alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms is particularly preferred.

[0078] In the silicon compound represented by the general formula (IV), R ８ or R ９ R is a group selected from a hydrogen atom or a linear or branched alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted cycloalkyl group, a phenyl group, an allyl group, and an aralkyl group, and may contain a heteroatom. ８ or R ９ As R, a linear or branched alkyl group having 1 to 10 carbon atoms and a cycloalkyl group having 5 to 8 carbon atoms are preferred, and a linear or branched alkyl group having 1 to 8 carbon atoms and a cycloalkyl group having 5 to 8 carbon atoms are particularly preferred. ８ and R ９ may be bonded to form a ring, in which case the ring may be formed by (NR ８ R ９ ) is preferably a perhydroquinolino group or a perhydroisoquinolino group.

[0079] In the silicon compound represented by the general formula (IV), R ７ , R ８ and R ９ may be the same or different.

[0080] In the silicon compound represented by the general formula (IV), R １０ is any group selected from an alkyl group, a cycloalkyl group, a phenyl group, an allyl group, and an aralkyl group having 1 to 4 carbon atoms, and may contain a heteroatom. １０ As the alkyl group, a linear or branched alkyl group having 1 to 4 carbon atoms is preferred.

[0081] In the silicon compound represented by the general formula (IV), r is 0 or 1 to 2, and specifically r is 0, 1, or 2. In the silicon compound represented by the general formula (IV), s is 0 or 1 to 2, and specifically s is 0, 1, or 2. In the silicon compound represented by the general formula (IV), r+s is 0 or 1 to 4, and specifically r+s is 0, 1, 2, 3, or 4.

[0082] Specific examples of such silicon compounds represented by the general formula (IV) include one or more organic silicon compounds selected from phenylalkoxysilanes, alkylalkoxysilanes, phenylalkylalkoxysilanes, cycloalkylalkoxysilanes, cycloalkylalkylalkoxysilanes, (alkylamino)alkoxysilanes, alkyl(alkylamino)alkoxysilanes, alkyl(alkylamino)silanes, alkylaminosilanes, and the like.

[0083] Particularly preferred silicon compounds in which s is 0 in the general formula (IV) are di-n-propyldimethoxysilane, diisopropyldimethoxysilane, di-n-butyldimethoxysilane, diisobutyldimethoxysilane, di-t-butyldimethoxysilane, t-butylmethyldimethoxysilane, t-butylethyldimethoxysilane, di-n-butyldiethoxysilane, t-butyltrimethoxysilane, t-butyltriethoxysilane, dicyclohexyldimethoxysilane, dicyclohexyldiethoxysilane, cyclohexylmethyldimethoxysilane, cyclohexylmethyldiethoxysilane, and cyclohexylethyl Examples of the organic silicon compound include one or more organic silicon compounds selected from dimethoxysilane, cyclohexylethyldiethoxysilane, dicyclopentyldimethoxysilane, dicyclopentyldiethoxysilane, cyclopentylmethyldimethoxysilane, cyclopentylmethyldiethoxysilane, cyclopentylethyldiethoxysilane, cyclohexylcyclopentyldimethoxysilane, cyclohexylcyclopentyldiethoxysilane, 3-methylcyclohexylcyclopentyldimethoxysilane, 4-methylcyclohexylcyclopentyldimethoxysilane, and 3,5-dimethylcyclohexylcyclopentyldimethoxysilane.

[0084] Examples of the silicon compound in which s is 1 or 2 in the above general formula (IV) include one or more organic silicon compounds selected from di(alkylamino)dialkoxysilanes, (alkylamino)(cycloalkylamino)dialkoxysilanes, (alkylamino)(alkyl)dialkoxysilanes, di(cycloalkylamino)dialkoxysilanes, vinyl(alkylamino)dialkoxysilanes, allyl(alkylamino)dialkoxysilanes, (alkoxyamino)trialkoxysilanes, (alkylamino)trialkoxysilanes, and (cycloalkylamino)trialkoxysilanes, and particularly preferred are ethyl(t-

[0033] Examples of suitable organosilicon compounds include bis(perhydroisoquinolino)dimethoxysilane, cyclohexyl(cyclohexylamino)dimethoxysilane, ethyl(t-butylamino)dimethoxysilane, bis(cyclohexylamino)dimethoxysilane, bis(perhydroisoquinolino)dimethoxysilane, bis(perhydroquinolino)dimethoxysilane, ethyl(isoquinolino)dimethoxysilane, diethylaminotrimethoxysilane, and diethylaminotriethoxysilane. Among these, preferred are one or more organosilicon compounds selected from bis(perhydroisoquinolino)dimethoxysilane, diethylaminotrimethoxysilane, and diethylaminotriethoxysilane.

[0085] The silicon compounds represented by the general formula (IV) may be used in combination of two or more kinds.

[0086] In the method for producing a propylene-based block copolymer according to the present invention, the catalyst for olefin polymerization comprises (A) a solid catalyst component for olefin polymerization, (B) an organoaluminum compound, and, if necessary, (C) an external electron donor compound, i.e., a contact product thereof. The catalyst for olefin polymerization may be prepared by contacting (A) the solid catalyst component for olefin polymerization, (B) the organoaluminum compound, and, if necessary, (C) the external electron donor compound in the absence of olefins, or may be prepared by contacting them in the presence of olefins (in a polymerization system), as described below.

[0087] In the method for producing a propylene-based block copolymer according to the present invention, the content ratio of each component constituting the olefin polymerization catalyst is not particularly limited and may be any as long as it does not affect the effects of the present invention, but typically, the catalyst contains preferably 1 to 2,000 moles, more preferably 50 to 1,000 moles, of the (B) organoaluminum compound per mole of titanium atom in the (A) solid catalyst component for olefin polymerization. Furthermore, the olefin polymerization catalyst preferably contains 0.002 to 10,000 moles, more preferably 0.010 to 2,000 moles, and even more preferably 0.010 to 0.500 moles of the (C) external electron donor compound per mole of the (B) organoaluminum compound.

[0088] The catalyst for olefin polymerization can be produced by contacting the (A) solid catalyst component for olefin polymerization with the (B) organoaluminum compound, and, if necessary, the (C) external electron donor compound with each other. That is, the catalyst can be produced by contacting the (A) solid catalyst component for olefin polymerization with the (B) organoaluminum compound with each other in the presence of the (C) external electron donor compound or in the absence of the external electron donor compound.

[0089] In producing the above-mentioned catalyst for olefin polymerization, when the contact of (A) the solid catalyst component for olefin polymerization with (B) the organoaluminum compound is carried out in the absence of (C) the external electron-donor compound, it is preferred that after the solid catalyst component for olefin polymerization (A) and the organoaluminum compound (B) are contacted with each other, the contact-treated product thus obtained is further contacted with the external electron-donor compound (C).

[0090] When producing the above-mentioned catalyst for olefin polymerization, the contact amounts of the above-mentioned (A) solid catalyst component for olefin polymerization and (B) organoaluminum compound, and the contact amount of the (C) external electron donor compound used as needed, may be appropriately determined depending on the composition of the catalyst for olefin polymerization to be obtained.

[0091] The inert gas concentration in the atmosphere during preparation of the olefin polymerization catalyst is preferably 0.0 to 1.0 mol / L, more preferably 0.0 to 0.5 mol / L, and even more preferably 0.0 to 0.1 mol / L.

[0092] The inert gas may be at least one selected from nitrogen gas, helium gas, neon gas, argon gas, and the like.

[0093] The catalyst for polymerizing olefins may be produced in the presence of the olefins to be polymerized, or may be produced in the absence of the olefins to be polymerized.

[0094] The temperature at which the components are brought into contact during the production of the olefin polymerization catalyst is preferably 40°C or lower, more preferably 0°C to 40°C, even more preferably 10°C to 40°C, and particularly preferably 10°C to 20°C.

[0095] In producing the olefin polymerization catalyst, the treatment time for contacting each component is preferably 10 seconds to 60 minutes, more preferably 30 seconds to 30 minutes, even more preferably 1 minute to 30 minutes, and particularly preferably 1 minute to 10 minutes.

[0096] In producing the above-mentioned catalyst for olefin polymerization, when (A) the solid catalyst component for olefin polymerization, (B) the organoaluminum compound, and, if necessary, (C) the external electron donor compound are brought into contact with each other, a reaction is initiated instantly, and the desired catalyst for olefin polymerization can be formed.

[0097] In the method for producing a propylene-based block copolymer according to the present invention, by using a catalyst for polymerizing olefins containing a specific solid catalyst component for polymerizing olefins (A) and an organoaluminum compound (B), even when subjected to a polymerization reaction at a relatively low temperature in the first polymerization step described below, the catalyst can easily exhibit sufficiently high polymerization activity, and can also easily exhibit high polymerization activity in the second polymerization step, and can easily produce a propylene-based block copolymer having a melt flow rate that is sufficiently high for practical use and a high content of a propylene / α-olefin copolymer component.

[0098] In the method for producing a propylene-based block copolymer according to the present invention, a first polymerization step is carried out using the above-mentioned catalyst for polymerization of olefins at a temperature of 45°C to 65°C to polymerize olefins containing 95 to 100% by mass of propylene to obtain a propylene-based polymer, and then a second polymerization step is carried out at a temperature of 50°C to 90°C to copolymerize olefins containing 5% by mass or more and less than 95% by mass of propylene and an α-olefin other than propylene in the presence of the propylene-based polymer to obtain a propylene / α-olefin copolymer.

[0099] In the method for producing a propylene-based block copolymer according to the present invention, in the first polymerization step, olefins containing 95 to 100% by mass of propylene are used, preferably olefins containing 97 to 100% by mass of propylene, and more preferably olefins containing 99 to 100% by mass of propylene.

[0100] In the method for producing a propylene-based block copolymer according to the present invention, the first polymerization step is carried out under a temperature condition of 45°C to 65°C, preferably under a temperature condition of 50°C to 65°C, and more preferably under a temperature condition of 55°C to 60°C.

[0101] In the method for producing a propylene-based block copolymer according to the present invention, by carrying out the first polymerization step under the above-mentioned temperature conditions, excessive polymerization reaction in the first polymerization step can be suppressed, and the above-mentioned specific catalyst for polymerizing olefins can be used, so that a propylene-based polymer as an intermediate product can be obtained while easily exhibiting high polymerization activity.

[0102] In the method for producing a propylene-based block copolymer according to the present invention, in the second polymerization step, olefins containing 5% by mass or more but less than 95% by mass of propylene and an α-olefin other than propylene are copolymerized in the presence of the propylene-based polymer obtained as an intermediate product to obtain a propylene / α-olefin copolymer.

[0103] In the method for producing a propylene-based block copolymer according to the present invention, the α-olefin other than propylene used in the second polymerization step is not particularly limited as long as it is at least one selected from α-olefins other than propylene, and examples thereof include at least one selected from ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, vinylcyclohexane, etc., with ethylene or 1-butene being preferred.

[0104] In the method for producing a propylene-based block copolymer according to the present invention, in the second polymerization step, olefins containing 5% by mass or more but less than 95% by mass of propylene and an α-olefin other than propylene are used, preferably olefins containing 10% by mass to 90% by mass of propylene and 10% by mass to 90% by mass of an α-olefin other than propylene, and more preferably olefins containing 20% ​​by mass to 80% by mass of propylene and 20% by mass to 80% by mass of an α-olefin other than propylene.

[0105] In the method for producing the propylene-based block copolymer according to the present invention, the second polymerization step is carried out under a temperature condition of 50°C to 90°C, preferably under a temperature condition of 55°C to 90°C, more preferably under a temperature condition of 65°C to 90°C, further preferably under a temperature condition of 70°C to 85°C, and particularly preferably under a temperature condition of 70°C to 80°C.

[0106] In the method for producing a propylene-based block copolymer according to the present invention, by carrying out a polymerization reaction in the second polymerization step using the above-mentioned specific catalyst for polymerizing olefins under the above-mentioned temperature conditions, it is possible to easily produce a propylene-based block copolymer having a high content of propylene / α-olefin copolymer while easily exhibiting excellent polymerization activity in the second polymerization step.

[0107] In the method for producing a propylene-based block copolymer according to the present invention, an olefin monomer such as propylene can be used in either a gaseous or liquid state, and the treatments in the first polymerization step and the second polymerization step can be carried out in the presence or absence of an organic solvent.

[0108] Specifically, in the first polymerization step, the polymerization temperature and polymerization time are adjusted to polymerize monomers in an amount corresponding to 50 to 70% by mass of the entire propylene-based block copolymer to be obtained, and then in the second polymerization step, propylene and other α-olefins (such as ethylene) are introduced to polymerize a rubber moiety such as an ethylene-propylene rubber (EPR) or an ethylene-propylene-1-butene terpolymer while adjusting the reaction conditions so that the proportion of the rubber moiety becomes 25.0 to 50.0% by mass of the entire propylene-based block copolymer to be obtained.

[0109] The polymerization reaction in the second polymerization step is generally preferably carried out by a gas-phase polymerization reaction in order to prevent the elution of rubber moieties such as EPR from the polypropylene particles. The polymerization reactions in the first and second polymerization steps may be carried out by either a continuous polymerization method or a batch polymerization method. Furthermore, the polymerization reaction in either the first or second polymerization step may be a single-stage or multi-stage process. When each step is carried out in multiple stages, the processes may be carried out under the same or different conditions.

[0110] In the method for producing a propylene-based block copolymer according to the present invention, the polymerization of olefins in the first polymerization step and the second polymerization step can be carried out by heating and pressurizing in a reactor (polymerization tank) such as an autoclave in the presence of a catalyst for olefin polymerization.

[0111] For example, a first polymerization step is carried out in which a monomer containing only propylene as an olefin is polymerized in a first polymerization tank to obtain a propylene-based polymer, and then a second polymerization step is carried out in a second or more stages (multistage polymerization tank) in which propylene and an α-olefin other than propylene (such as ethylene) are copolymerized in the presence of the obtained propylene-based polymer to obtain a propylene / α-olefin random copolymer, thereby producing the desired propylene-based block copolymer.

[0112] The polymerization pressure in the first polymerization step and the second polymerization step is preferably 10 MPa or less, more preferably 5 MPa or less. Furthermore, the polymerization time (residence time of the reaction raw materials) in the first polymerization step and the second polymerization step is suitably 1 minute to 5 hours in total.

[0113] In the method for producing a propylene-based block copolymer according to the present invention, when olefins are polymerized using the catalyst for olefin polymerization (also referred to as main polymerization), it is preferable to carry out prepolymerization prior to the main polymerization in order to further improve the catalytic activity, stereoregularity, particle properties of the polymer to be produced, etc., and in the prepolymerization, the same olefins as in the main polymerization or a monomer such as styrene can be used.

[0114] In carrying out the prepolymerization, the components constituting the catalyst for olefin polymerization and the monomer (olefin) may be contacted in any order, but it is preferred to first charge an organoaluminum compound into a prepolymerization system set in an inert gas atmosphere or an olefin gas atmosphere, then charge and contact the above-mentioned solid catalyst component for olefin polymerization, and then contact an olefin such as propylene alone or a mixture of propylene and an α-olefin other than propylene. In the above prepolymerization, when an external electron donor compound (C) is further charged into the prepolymerization system set in an inert gas atmosphere or an olefin gas atmosphere, it is preferred to first charge an organoaluminum compound (B) into the prepolymerization system set in an inert gas atmosphere or an olefin gas atmosphere, then charge and contact the external electron donor compound (C), and then contact the above-mentioned solid catalyst component for olefin polymerization (A), and then contact an olefin such as propylene alone or a mixture of propylene and an α-olefin other than propylene.

[0115] The propylene-based block copolymer obtained by the production method according to the present invention includes the propylene-based block copolymer according to the present invention described below.

[0116] Next, the propylene-based block copolymer obtained by the production method according to the present invention will be described.

[0117] The propylene-based block copolymer obtained by the production method according to the present invention preferably has a melt flow rate (MFR) of 10 to 200 g / 10 min, more preferably 15 to 150 g / 10 min, and even more preferably 20 to 100 g / 10 min.

[0118] In the present application, the melt flow rate (MFR) indicating the melt flowability of a polymer means a value measured in accordance with ASTM D 1238 and JIS K 7210.

[0119] In the method for producing a propylene-based block copolymer according to the present invention, the propylene-based block copolymer obtained has a propylene / α-olefin copolymer content of preferably 25.0 to 50.0 mass%, more preferably 30.0 to 45.0 mass%, and even more preferably 35.0 to 40.0 mass%.

[0120] In the present application, the content of the propylene / α-olefin copolymer in the propylene-based block copolymer refers to the value obtained by charging 5.0 g of the propylene-based block copolymer and 250 ml of p-xylene into a flask equipped with a stirrer, dissolving the polymer over 2 hours while maintaining the temperature of the p-xylene inside the flask below the boiling point (137 to 138°C) by raising the external temperature to above the boiling point of xylene (about 150°C), and then cooling the liquid temperature to 23°C over 1 hour, filtering and separating the insoluble and soluble components, collecting the solution of the dissolved components, distilling off the p-xylene by heating and drying under reduced pressure, determining the weight of the residue obtained, and calculating the relative proportion (% by mass) to the produced polymer (propylene-based block copolymer).

[0121] In the method for producing a propylene-based block copolymer according to the present invention, the propylene-based block copolymer obtained preferably has a propylene polymer content of 50.0 to 75.0 mass%, more preferably 55.0 to 70.0 mass%, and even more preferably 60.0 to 65.0 mass%.

[0122] In the present application, the content of the propylene polymer in the propylene block copolymer refers to the value obtained by subtracting the propylene / α-olefin copolymer content (mass%) determined by the above-mentioned method and the ethylene content (mass%) in the xylene-insoluble matter from the total weight (mass%) of the produced polymer (propylene block copolymer), where the total weight of the produced polymer (propylene block copolymer) is taken as 100 (mass%). The ethylene content in the xylene-insoluble matter refers to the value calculated by sampling a small amount of the xylene-insoluble matter obtained when measuring the propylene / α-olefin copolymer content and forming it into a film using a hot press, and then measuring the absorbance and film thickness using a Fourier transform infrared spectrometer (FT-IR, Thermonicolet, AvaTar) based on a calibration curve prepared from multiple samples with known contents. Measurement wavelength: 720 cm －１ and 1150 cm －１ Film thickness: 0.1-0.2 mm

[0123] According to the present invention, there can be provided a method for easily producing a propylene-based block copolymer which exhibits excellent polymerization activity in a first polymerization step in which a homopolymerization reaction of propylene or a copolymerization reaction of propylene with a small amount of an α-olefin (excluding propylene) is carried out, and also exhibits excellent polymerization activity in a second polymerization step in which a copolymerization reaction of propylene and an α-olefin (excluding propylene) is carried out in the presence of the propylene-based polymer obtained in the first polymerization step, and which has a melt flow rate that is sufficiently high for practical use and a high content of a propylene / α-olefin copolymer component.

[0124] EXAMPLES Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples in any way.

[0125] (Examples 1 to 3, Comparative Examples 1 and 2) (1) Preparation of a solid catalyst component for olefin polymerization Into a 500 mL flask equipped with a stirrer and purged with nitrogen gas, 10 g (87.4 mmol) of diethoxymagnesium, 80 mL of toluene, 20 mL of titanium tetrachloride, and 12.0 mmol (2.6 g) of 2-isopropyl-2-isopentyl-1,3-dimethoxypropane were placed and reacted with each other for 120 minutes at a temperature of 100°C. After completion of the reaction, the contact product was washed four times with 60 mL of toluene at 100°C. A new toluene solution of titanium tetrachloride in which the volume ratio of titanium tetrachloride to toluene (titanium tetrachloride / toluene volume ratio) was 0.28 was added, and the mixture was stirred and reacted at 100°C for 15 minutes. After the reaction, the supernatant was removed. This operation was repeated once more, and the mixture was washed six times with 75 mL of n-heptane at 40°C to obtain a solid catalyst component for olefin polymerization.

[0126] (2) Preparation of a catalyst for olefin polymerization A catalyst for olefin polymerization was prepared by charging 2.42 mmol of triethylaluminum and 0.0030 mmol, in terms of titanium atom, of the solid catalyst component for olefin polymerization obtained in (1) above into a 2.0 L autoclave equipped with a stirrer and whose internal volume was completely purged with nitrogen gas.

[0127] (3) Production of Ethylene-Propylene Block Copolymer After the catalyst for olefin polymerization was prepared in (2), 3.5 liters of hydrogen gas and 1.2 liters of liquefied propylene were charged into the autoclave equipped with a stirrer in which the catalyst for olefin polymerization had been prepared. Prepolymerization was carried out at 20°C for 5 minutes, and then the temperature was raised to carry out a homopropylene (homo-stage) polymerization reaction as a first polymerization step at the polymerization temperature and for the polymerization time shown in Table 1.

[0128] After the homopropylene (homo-stage) polymerization reaction, propylene, ethylene, and hydrogen were fed under a pressure of 1.2 MPa to the stirrer-equipped autoclave in which the homopropylene (homo-stage) polymerization reaction had been carried out at rates of 2.3 L / min, 1.7 L / min, and 0.086 L / min, respectively, and copolymerization reactions were carried out at the polymerization temperatures and polymerization times shown in Table 1 to produce propylene / ethylene copolymers, thereby obtaining various ethylene-propylene block copolymers.

[0129] For the resulting ethylene-propylene block copolymer, the propylene polymerization activity (homo-stage polymerization activity, g / g-catalyst), ethylene-propylene block copolymerization (ICP) activity (g / g-catalyst), total polymerization activity (g / g-catalyst), block ratio of the resulting block copolymer (polymerization ratio of copolymerized portion, mass%), melt flow rate (MFR) of the resulting block copolymer, ethylene-propylene copolymer (EPR) content (mass%) in the resulting block copolymer, and ethylene content (mass%) in the ethylene-propylene copolymer (EPR), were measured by the following methods. The results are shown in Table 1.

[0130] <Propylene polymerization activity> The homo-stage polymerization activity in the copolymerization reaction was calculated by the following formula: Homo-stage polymerization activity (g / g-catalyst) = (G(g) - F(g)) / mass (g) of solid catalyst component, where G(g) is the mass (g) of the autoclave after the homo-PP polymerization reaction was completed and the unreacted monomer was removed, and F(g) is the mass (g) of the autoclave.

[0131] <Ethylene-Propylene Block Copolymerization (ICP) Activity (g / g-Catalyst)> The copolymerization (ICP) activity during the formation of an ethylene-propylene block copolymer was calculated by the following formula: Copolymerization (ICP) Activity (g / g-Catalyst) = ((I(g) - G(g)) / Mass (g) of solid catalyst component contained in olefin polymerization catalyst) where I(g) is the mass (g) of the autoclave after completion of the copolymerization reaction, and G(g) is the mass (g) of the autoclave after completion of the homo-PP polymerization reaction and removal of unreacted monomers.

[0132] <Total polymerization activity (g / g-catalyst)> The total polymerization activity (g / g-catalyst) during the production of an ethylene-propylene block copolymer was calculated by the following formula: Total polymerization activity (g / g-catalyst) = Homostage polymerization activity (g / g-catalyst) + Copolymerization (ICP) activity (g / g-catalyst)

[0133] <Block ratio (mass %)> The block ratio of the resulting ethylene-propylene block copolymer was calculated by the following formula: Block ratio (mass %) = {(I(g) - G(g)) / (I(g) - F(g))} × 100, where I is the mass (g) of the autoclave after completion of the copolymerization reaction, G is the mass (g) of the autoclave after completion of the homopolypropylene polymerization and removal of unreacted monomers, and F is the mass (g) of the autoclave.

[0134] <Melt Flow Rate (MFR)> The melt flow rate (MFR), which indicates the melt flowability of the resulting ethylene-propylene block copolymer, was measured according to ASTM D 1238 and JIS K 7210.

[0135] <Ethylene Propylene Copolymer (EPR) Content (Xylene Soluble Fraction in ICP Polymer)> 5.0 g of copolymer (ethylene-propylene block copolymer) and 250 mL of p-xylene were charged into a flask equipped with a stirrer. The external temperature was then set to approximately 150°C, and stirring was continued for 2 hours while maintaining reflux of p-xylene (boiling point 137-138°C) in the flask to dissolve the polymer. The solution was then cooled to a liquid temperature of 23°C over 1 hour, and the xylene soluble fraction (EPR) and xylene insoluble fraction (XI) were separated by evaporation. The soluble fraction was collected together with the solution, and the p-xylene was distilled off by heating and drying under reduced pressure. The weight of the resulting residue was determined, and the relative proportion (mass%) to the resulting polymer (ethylene-propylene block copolymer) was calculated to provide the EPR content (xylene soluble fraction in the ethylene-propylene block copolymer).

[0136] <Ethylene Content in EPR Component> A small amount of the xylene soluble fraction (EPR) separated at the EPR content of the copolymer was sampled and formed into a film using a hot press. The absorbance and film thickness were measured using a Fourier transform infrared spectrometer (FT-IR) (Avatar, manufactured by Thermonicolet), and the ethylene content in the xylene soluble fraction (XS) of the ICP was calculated based on a calibration curve prepared from multiple samples with known contents. Measurement wavelength: 720 cm －１ and 1150 cm －１ Film thickness: 0.1 to 0.2 mm

[0137] <Ethylene Content in Xylene-Insoluble Fraction (XI)> A small amount of the xylene-insoluble fraction (XI) separated to determine the EPR content of the copolymer was sampled and formed into a film by a hot press, and then the ethylene content in the xylene-insoluble fraction (XI) of the ICP was calculated in the same manner as for the ethylene content in the xylene-soluble fraction (XS) of the ICP.

[0138] (Example 4, Comparative Example 3) (1) Preparation of a solid catalyst component for olefin polymerization Into a 500 mL flask equipped with a stirrer and purged with nitrogen gas, 10 g (87.4 mmol) of diethoxymagnesium, 55 mL of toluene, 15 mL of titanium tetrachloride, and 10.0 mmol (2.2 g) of 2-isopropyl-2-isopentyl-1,3-dimethoxypropane were placed and reacted by contact with each other at a temperature of 100°C for 180 minutes. After completion of the reaction, the contact product was washed five times with 55 mL of toluene at 90°C. A new toluene solution of titanium tetrachloride in which the volume ratio of titanium tetrachloride to toluene (titanium tetrachloride / toluene volume ratio) was 0.33 was added, and the mixture was stirred and reacted at 100°C for 15 minutes. After the reaction, the supernatant was removed. This operation was repeated three more times, and the mixture was washed six times with 75 mL of n-heptane at 40°C to obtain a solid catalyst component for olefin polymerization.

[0139] (2) Preparation of a catalyst for olefin polymerization A catalyst for olefin polymerization (ethylene-propylene copolymerization catalyst) was prepared by charging 2.42 mmol of triethylaluminum and 0.030 mmol, in terms of titanium atom, of the solid catalyst component for olefin polymerization obtained in (1) above into a 2.0 L autoclave equipped with a stirrer and whose interior air had been completely purged with nitrogen gas.

[0140] (3) Production of Ethylene-Propylene Block Copolymer After the catalyst for olefin polymerization was prepared in (2), 3.5 liters of hydrogen gas and 1.2 liters of liquefied propylene were charged into the autoclave equipped with a stirrer in which the catalyst for olefin polymerization had been prepared. Prepolymerization was carried out at 20°C for 5 minutes, and then the temperature was raised to carry out a homopropylene (homo-stage) polymerization reaction as a first polymerization step at the polymerization temperature and for the polymerization time shown in Table 1.

[0141] After the homopropylene (homo-stage) polymerization reaction, propylene, ethylene, and hydrogen were fed under a pressure of 1.2 MPa to the stirrer-equipped autoclave in which the homopropylene (homo-stage) polymerization reaction had been carried out at rates of 2.3 L / min, 1.7 L / min, and 0.086 L / min, respectively, and copolymerization reactions were carried out at the polymerization temperatures and for the polymerization times shown in Table 1 to produce ethylene-propylene copolymers, thereby obtaining various ethylene-propylene block copolymers.

[0142] For the resulting ethylene-propylene block copolymer, the propylene polymerization activity (homo-stage polymerization activity, g / g-catalyst), ethylene-propylene block copolymerization (ICP) activity (g / g-catalyst), total polymerization activity (g / g-catalyst), block ratio of the resulting block copolymer (polymerization ratio of copolymerized portion, mass%), melt flow rate (MFR) of the resulting block copolymer, content (mass%) of ethylene-propylene copolymer (EPR) in the resulting block copolymer, and content (mass%) of ethylene-propylene copolymer (EPR) in the ethylene-propylene copolymer were measured by the same methods as in Example 1. The results are shown in Table 1.

[0143] (Comparative Examples 4 and 5) (1) Preparation of a solid catalyst component for olefin polymerization 10 g (87.4 mmol) of diethoxymagnesium, 90 mL of toluene, 30 mL of titanium tetrachloride, and 15.8 mmol (4.4 g) of dibutyl phthalate were placed in a 500 mL flask equipped with a stirrer and purged with nitrogen gas, and the contents were allowed to contact and react with each other at a temperature of 90°C for 180 minutes. After completion of the reaction, the contact product was washed four times with 75 mL of toluene at 90°C. A new toluene solution of titanium tetrachloride in which the volume ratio of titanium tetrachloride to toluene (titanium tetrachloride / toluene volume ratio) was 0.74 was added, and the mixture was stirred and reacted at 110°C for 60 minutes. After the reaction, the supernatant was removed. The mixture was then washed six times with 75 mL of n-heptane at 40°C to obtain a solid catalyst component for olefin polymerization.

[0144] (2) Formation of a catalyst for olefin polymerization A catalyst for olefin polymerization (ethylene-propylene copolymerization catalyst) was prepared by charging 2.42 mmol of triethylaluminum, 0.24 mmol of cyclohexylmethyldimethoxysilane, and 0.034 mmol, calculated as titanium atom, of the solid catalyst component for olefin polymerization obtained in (1) above into a 2.0 L autoclave equipped with a stirrer and whose interior air had been completely purged with nitrogen gas.

[0145] (3) Production of Ethylene-Propylene Block Copolymer After the catalyst for olefin polymerization was prepared in (2), 3.5 liters of hydrogen gas and 1.2 liters of liquefied propylene were charged into the autoclave equipped with a stirrer in which the catalyst for olefin polymerization had been prepared. Prepolymerization was carried out at 20°C for 5 minutes, and then the temperature was raised to carry out a homopropylene (homo-stage) polymerization reaction as a first polymerization step at the polymerization temperature and for the polymerization time shown in Table 1.

[0146] After the homopropylene (homo-stage) polymerization reaction, propylene, ethylene, and hydrogen were fed under a pressure of 1.2 MPa to the stirrer-equipped autoclave in which the homopropylene (homo-stage) polymerization reaction had been carried out at rates of 2.3 L / min, 1.7 L / min, and 0.086 L / min, respectively, and copolymerization reactions were carried out at the polymerization temperatures and for the polymerization times shown in Table 1 to produce ethylene-propylene copolymers, thereby obtaining various ethylene-propylene block copolymers.

[0147] For the resulting ethylene-propylene block copolymer, the propylene polymerization activity (homo-stage polymerization activity, g / g-catalyst), ethylene-propylene block copolymerization (ICP) activity (g / g-catalyst), total polymerization activity (g / g-catalyst), block ratio of the resulting block copolymer (polymerization ratio of copolymerized portion, mass%), melt flow rate (MFR) of the resulting block copolymer, content (mass%) of ethylene-propylene copolymer (EPR) in the resulting block copolymer, and content (mass%) of ethylene-propylene copolymer (EPR) in the ethylene-propylene copolymer were measured by the same methods as in Example 1. The results are shown in Table 1.

[0148]

[0149] As can be seen from Table 1, in Examples 1 to 3, a specific solid catalyst component for olefin polymerization containing a 1,3-diether compound as an internal electron donor compound and an olefin polymerization catalyst containing an organoaluminum compound were used, and the polymerization reaction was carried out at a relatively low temperature within the range of 45°C to 65°C in the first polymerization step (homopolymerization stage). This makes it possible to easily exhibit high polymerization activity in the first polymerization step (homopolymerization stage) and the second polymerization step (copolymerization stage), and to easily produce an ethylene-propylene block copolymer having a melt flow rate (MFR) that is sufficiently high for practical use, a high block ratio, and an EPR content.

[0150] On the other hand, Table 1 shows that in Comparative Examples 1 and 2, the olefin polymerization catalyst was subjected to the polymerization reaction at a temperature exceeding 65°C in the first polymerization step (homopolymerization stage), which resulted in a low polymerization activity in the second polymerization step (copolymerization stage), and only ethylene-propylene block copolymers having low block ratios and EPR contents were obtained.

[0151] Furthermore, Table 1 shows that in Example 4 as well, a specific solid catalyst component for polymerizing olefins containing a 1,3-diether compound as an internal electron donor compound and a catalyst for polymerizing olefins containing an organoaluminum compound were used, and the polymerization reaction was carried out at a relatively low temperature within the range of 45°C to 65°C in the first polymerization step (homopolymerization stage). This made it possible to easily demonstrate high polymerization activity in the first polymerization step (homopolymerization stage) and the second polymerization step (copolymerization stage), and to easily produce an ethylene-propylene block copolymer having a melt flow rate (MFR) sufficiently high for practical use, a high block ratio, and an EPR content.

[0152] On the other hand, Table 1 shows that in Comparative Example 3, the olefin polymerization catalyst was subjected to a polymerization reaction at a temperature exceeding 65°C in the first polymerization step (homopolymerization stage), which resulted in a low polymerization activity in the second polymerization step (copolymerization stage), and only an ethylene-propylene block copolymer having a low block ratio and EPR content was obtained.

[0153] Furthermore, Table 1 shows that in Comparative Examples 4 and 5, a solid catalyst component for olefin polymerization that does not contain a 1,3-diether compound as an internal electron donor compound and a catalyst for olefin polymerization that contains an organoaluminum compound were used, and therefore the polymerization activity in the first polymerization step (homopolymerization stage) and the second polymerization step (copolymerization stage) was poor, and only ethylene-propylene block copolymers with low melt flow rates (MFR) were obtained.

[0154] According to the present invention, there can be provided a method for easily producing a propylene-based block copolymer which has excellent polymerization activity in a first polymerization step in which a homopolymerization reaction of propylene or a copolymerization reaction of propylene with a small amount of an α-olefin (excluding propylene) is carried out, and also has excellent polymerization activity in a second polymerization step in which a copolymerization reaction of propylene and an α-olefin (excluding propylene) is carried out in the presence of the propylene-based polymer obtained in the first polymerization step, and which has a high melt flow rate and a high content of a propylene / α-olefin copolymer component.

Claims

1. A method for producing a propylene-based block copolymer, comprising the steps of: (A) using a catalyst for olefin polymerization containing a solid catalyst component for olefin polymerization containing titanium, magnesium, halogen, and a 1,3-diether compound which is an internal electron donor compound; and (B) an organoaluminum compound; carrying out a first polymerization step of polymerizing olefins containing 95-100% by mass of propylene at a temperature of 45°C to 65°C to obtain a propylene-based polymer; and (B) carrying out a second polymerization step of copolymerizing olefins containing 5% by mass or more but less than 95% by mass of propylene and an α-olefin other than propylene in the presence of the propylene-based polymer at a temperature of 50°C to 90°C to obtain a propylene / α-olefin copolymer.

2. The organoaluminum compound (B) is represented by the following general formula (I): １ ｐ AlQ ３－ｐ (I) (wherein, R １ is an alkyl group having 1 to 6 carbon atoms, Q is a hydrogen atom or a halogen atom, p is 0<p≦3, R １ When there are multiple R １ may be the same or different, and when a plurality of Q's are present, each Q may be the same or different. The method for producing a propylene-based block copolymer according to claim 1, 3. The method for producing a propylene-based block copolymer according to claim 1, wherein the catalyst for olefin polymerization further contains (C) an external electron donor compound.

4. A method for producing a propylene-based block copolymer according to any one of claims 1 to 3, wherein the content of propylene / α-olefin moieties in the resulting propylene-based block copolymer is 25.0 to 50.0 mass%.

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